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MASTER`S THESIS

1. 32 SCNSOLSs ain eye on tas ei See EN SE he ee ee eee ee 3 21 AlleskysGamiera 22 4 ako eam ad D oo en eee Ee wr ee es Software design 4 1 System definition A AE BO ee Oe a ee ee db ae as 4 2 Communication between programas ADV ECP A A A el et Peter ord 4 2 2 Dynamic Data Exchange ee ee 4 2 3 SvalPoint high layer protocols s 2 0 00 o 4 2 4 Erroneous commands and feedback to client o o 4 3 The current version of SvalPoint eee Pointing algorithms Del Geo POIS ie oP A ae A a BR OR ot ea A E 5 1 1 Calculating the vector between points defined by geodetic coordinates 5 1 2 Transferring vector from IWRF into PSRF o o a 5 1 3 Representing a vector in spherical coordinate system o o 5 2 Direction based pointing e 5 2 1 Calculating the vector from the instrument to the target Calibration 6 1 Geodetic positioning of the instruments and sensors o e e 6 1 1 Differential GPS 101 A A A A ee eee Cos 6 1 2 The meas r ments cz vc a al soe a 6 2 Home attitude determination of the instruments and sensors 6 2 1 Yaw Calibration a tio n ple ye Se pl a Ee a A 6 2 2 Pitch and Roll calibration e 16 16 16 17 17 18 18 19 19 21 22 22 22 23 24 25 26 26 28 29 30 31 H o a wD gt 6 3 All sky
2. sin 0 sin y z cos p 7 1 T where 0 lt 80 lt 9 and 0 lt p lt r Out of the angle errors for all possible target directions the maximum error is chosen Both most probable and worst case scenarios are investigated for being able to estimate the affect of error on system accuracy The height of sensor is set to be 520 m the height of the KHO station The distance between sensor and instrument varies between 0 to 22 5 m these distances being the most realistic esti mations for future situations the span of 10 adjacent rooms The height of the target is calculated for the values 70 and 550 km based on Str mer 1955 presenting the height distribution of a large number of auroral observations between 1911 1944 See Figure 7 1 The height measurements have been done by triangulation 43 500 1000 4400 300 200 00 MN N 100 _ gt ho et 3 i aes O 500 1000 Figure 7 1 The distribution of auroral heights in Str mer 1955 The plot shows the number of events on axis x versus the height of the occurrences Image adapted from Brekke 2012 First the worst case calculations are presented with the sensor instrument direction vectors being 1 0 0 0 1 0 and 0 0 1 in North East Up coordinates See Figure 7 3 and Figure 7 2 for the results Based on these images one can see that the best configuration for sensor and instrument would be to be atop of each other Figure 7 3 however that
3. cos p sin A 5 4 cos p 0 sin p Finally according to Hofmann Wellenhof et al 2001 the expression for the vector xij in IWRF can be found by the scalar multiplication of its Cartesian coordinates with the vectors expressing the axes of the local level reference frame Therefore the last piece of the series of expressions we have been looking for is Nij ni Xij zj ej e Xij 5 5 Nij uz Xij 5 1 2 Transferring vector from IWREF into PSRF To find a vector in the PSRF xpsrr based on its representation in the IWRF xrwrr a translation and a rotation shall be performed The spatial offset between the centre of the IWRF and PSRF is T as discussed in the beginning of Chapter 5 represented in IWRF The translation is done by subtraction of the vector components of T After the translation the rotation of the coordinate system around the vector shall be performed with use of rotation matrices for the transformation The rotation angles are defined as roll pitch and yaw rotations around the three axis of the coordinate system Given that the reference systems are left handed the following matrices are used for the rotations around axes for the different axes sin 0 0 cos cos w sin y 0 QY siny cos w 0 0 0 1 The order of the transformation is roll pitch followed by yaw The corresponding rotation matrices to these angles are Qx for the roll 7 Qy for the pitch 9 and Q for the yaw
4. CEs CAs nAzimuthPSRF CEs nElevationPSRF Str nAzimuthPSRF_C sAzimuthPSRF Str nElevationPSRF_C sElevationPSRF Send azimuth command donea false New command sendemd2 FL inttostr nAzimuthPSRF_C WaitOnMotors abs nAzimuthPSRF_C donea true Send elevation command donee false New command sendemdl FL inttostr nElevationPSRF_C WaitOnMotors abs nElevationPSRF_C else donee true end else errorinCmd True Angles out of range errorinCmd True COM port not connected Send feedback when command executed 73 if donee True and errorinCmd False then AContext Connection Socket WriteLn DateTimeToStr Now _FS_Ikea Command_executed else if errorinCmd True then AContext Connection Socket WriteLn DateTimeToStr Now FS Ikea Error in command end End of azimuth and elevation command Listing F 7 shows the procedure that is called upon the reception of a character on the COM port All characters received on the port are part of the feedback from the PTU D46 unit in this case Since the characters arrive with a high rate to the port they are read as strings as there is quite a high chance that by the time the procedure is called there are several characters available for reading All read character groups are assembled into one string until the phrase sought is contained in the string The phrase is characteristic to
5. SvalPoint A Multi track Optical Pointing System Kinga Albert 2014 Master of Science 120 credits Spacecraft Design Lulea University of Technology Department of Computer Science Electrical and Space Engineering LULEA UNIVERSITY OF TECHNOLOGY LULEA wy OF TECHNOLOGY UNIS Kinga Albert SvalPoint A Multi track Optical Pointing System Completed at The University Centre in Svalbard The Kjell Henriksen Observatory Supervisor Prof Dr Fred Sigernes The University Centre in Svalbard Longyearbyen Norway Examiner Dr Jana Mendrok Lulea University of Technology Kiruna Sweden Master s Thesis Lulea University of Technology 20 August 2014 Department of Computer Science Electrical and Space Engineering Division of Space Technology Kiruna Abstract The Kjell Henriksen Observatory KHO is researching the middle and upper atmosphere with optical instruments It is located in a remote region 15 km away from Longyearbyen in Svalbard Norway During the auroral season it is accessible only by special transportation snowmobile or band wagon and during its approach protection against polar bears is also necessary Due to these inconveniences a pointing system for the remote control of the instruments was desired The purpose of this thesis has been to develop a system optimising operations at KHO with room for further extensions SvalPoint offers a solution for multiple instrument pointing through the inter
6. the value of azimuth in degrees measured on the sensor in North East Up reference frame the value of elevation in degrees measured on the sensor in North East Up reference frame e Direction based pointing azel keyword AZELH AzEIH Azelh or azelh the value of latitude in degrees defining the place of sensor the value of longitude in degrees defining the place of sensor the value of altitude in metres defining the place of sensor the value of azimuth in degrees measured on the sensor in North East Up reference frame the value of elevation in degrees measured on the sensor in North East Up reference frame the height of target in kilometres e End connection keyword END End or end 61 E 4 Known issues and quick trouble shooting E 4 1 SvalCast is not responding after the first command was sent The most probable cause of this issue is rooted in COM port settings in the server The program does stop responding in some cases related to lack of COM port connection Please verify the COM port settings from the server application but also check that all RS232 cables are connected to the computer that the motor control unit is on and all motors are powered Please restart the server programs then kill the SvalCast from the Task Manager and try it again E 4 2 SvalCast is not connecting to the servers First make sure that the computer that you launched SvalC
7. The server applications are ought to be installed already on the computers In case they are not copy the folder of each server directly to the C in case of the PTU46 Tracker and KeoSkyScanner and to the D directory in the case of the Fs Ikea Tracker When the programs are launched they look as in Figure E 1 Verify the IP address of the computer also note the Port The same Port number shall be used in the client applications After all parameters are set correctly connect it to the internet by clicking the Connect to Internet button If continuous logging is not desired remove the tick from the check box In that case you can save the content of the dialogue window by clicking Save log For emptying the log file click Clear Log The log file can be accessed in the directory of the program The files are named FS_IKEAScanner_log txt KeoSkyScanner_log txt and PTU46Tracker_log txt for the three different instruments Also make sure that the COM ports are set correctly for the instruments being one of the most common troubles Access it through the Settings tab then Port Settings Verify the rest of the settings through the other tabs Use the Help tabs for more information The second part of the system is the client That can be launched on any computer registered as part of the KHO network The software is named SvalCast Launch it and select the instruments from the list that you wish to control then click
8. a connection between the server and client and one between client and control interfaces As discussed in Chapter 1 as well it is desired to have a remote control over the server programs from any location This goal demands a connection with Internet Protocol IP between the client and the server one that is suited to transfer short strings The best way to establish a communication optimal for this task has been identified to be a network socket Two transport protocols has been considered the User Datagram Protocol UDP and Transmission Control Protocol TCP The TCP has been chosen as it is well suited for applications that require high reliability however transmission time is not critical In TCP there is absolute guarantee that the data transferred remains intact and arrives in the same order in which it was sent by the establishment of an enduring connection between computer and remote host In contrast the UDP is faster but it does not guarantee that the data arrives at all a major disadvantage over the TCP in this case See Section 4 2 1 for more information on the TCP protocol The control interface and client run on the same computer therefore any connection that ensures com munication between two programs in Microsoft Windows is satisfactory as long as the communication is fast enough for handling the data stream Two options are considered one of them being the use of the clipboard the other one the Dynamic Data Exchange The clipb
9. lt TX and nElevationPSRF gt TN then begin Str nAzimuthPSRF sAzimuthPSRF Str nElevationPSRF sElevationPSRF Send elevation command donea false New command SendCmd PP sAzimuthPSRF while donea false do begin timerl enabled true sleep 100 SendCmd PP end timerl enabled false Send azimuth command donee false New command SendCmd TP sElevationPSRF while donee false do begin timerl enabled true sleep 100 SendCmd TP end timerl enabled false end else errorinCmd True Angles out of range else errorinCmd True COM port not connected end Send feedback when command executed if donee True and errorinCmd False then AContext Connection Socket WriteLn DateTimeToStr Now PTU_D46 Command executed else if errorinCmd True then AContext Connection Socket WriteLn DateTimeToStr Now PTU_D46 Error in command Memol Lines Add Azimuth _ sAzimuthPSRF Elevation sElevationPSRF end End of azimuth and elevation command 70 End command until sInCommand End or sInCommand END or sInCommand end AContext Connection Socket WriteLn PTU_D46 Connection ended AContext Connection Disconnect end Listing F 6 shows the AzEl command code for the Fs Ikea instrument It is shown in order to illustrate the n
10. 5 4 5 5 5 6 5 7 6 1 6 2 6 3 6 4 6 5 6 7 6 8 7 1 7 2 Sketch of the test system used for the implementation of the pointing algorithms 9 Illustration of the problem solved in the airborne image mapper software 12 Allesky lens Model ranor ea Ga tie a cel op Bey HB ee ig OE en debe a 14 The graphical user interface of the SvalTrack II software o o 15 The Narrow Field of view sCMOS camera o 16 The Fs Ikea spectrograph ee 17 The PTU DAG plato e Pa Bat A A S A A 18 Thesallisky Camera y id a AT IIA ad le ce eae tay 18 Overview of the data exchange between the system parts o o 20 The general network model followed 2 0 0 0 000000 000000000000 21 The client server model of the SvalPoint System o o e 24 Illustration of Cartesian coordinates X Y Z and geodetic coordinates p A h 26 Global and local level coordinates o 27 Measurement quantities in the PSRF 0 e e 29 Top view illustration of the system showing effect of spatial displacement between the instrument and sensor ss e di E a eo dA pe EA ee 30 Illustration of the system from the side showing effect of spatial displacement between the instrument and sensor a sro do beth es he RR ate Eke Deri ee S OGA 30 Calculating the components x or ni y or e z or u of a vector v defined by azimuth w and elevation Y sont Po VR
11. Connect Feedback from the servers appear in the Info field If the 59 o e kd e Settings Settings Initializes motors jp 158 39 49 101 Port 8080 p 158 3949142 Port 8080 Clear Log Save log Clear Log Save log Connect to Internet Connect to Internet Disconnect from Intemet V Continuous Logging Disconnect from Intemet Y Continuous Logging o Settings jp 158 39 49 110 Port 8080 Clear Log _ Savelog ave log Connect to Intemet Disconnect from Internet Figure E 1 The user interface of the server applications IP address or Port number is incorrect edit them in the Tracker_Console_Clients txt file Use this file if you wish to add new instrument as well The format is the following each instance on new row Displayed name IP address Port number selection status 0 for not selected and 1 for selected There shall be no empty row between the different instruments This client connects to a command interface The available command interfaces currently are SvalTrack II and Sval X Camera Launch one of these programs Note it is possible to launch both of them at the same time however it is counter advised In the SvalTrack II select any satellite or celestial body for tracking In the Sval X Camera click on the image acquired by the all sky camera for instrument control On the settings of these
12. Det A ae eh a Se 31 Calculating the magnitude of vector based on the height of the target 32 DGPS station and user on Svalbard at KHO o e e e 34 The first target of pointing for the yaw angle calibration 36 Pictures taken of the first target during the yaw calibration 0 36 Second calibration target Adventstoppen o 37 The third validation target Hiorthhamn e 37 Examples for images recorded during the calibration of the fish eye lens 39 Top view of the calibration set up Illustration of the effect of a spatial offset of the rotational axis of the arm and the centre of the camera e e 40 Calculating the angle for the fish eye lens based on the angle measured in the calibration A aes ad secgeeks Ged aes AS we Bah OL A Moen Po aed rae Win go eb 40 The distribution of auroral heights 2 0 a 44 The pointing error as function of height of target and distance between sensor and instrument if the direction of instrument is the 1 0 0 or 0 1 0 unit vector from sensor and the set value in SvalPoint for the height of target is 110 km o o 45 7 3 7 4 75 8 1 A l A 2 A 3 B 1 D 1 D 2 E 1 The pointing error as function of height of target and distance between sensor and instrument if the direction of instrument is the 0 0 1 unit vector from sensor and the set valu
13. Figure 7 5 Azimuth angle error degrees Height of target km Distance between sensor and instrument m 0 01 0 005 Elevation angle error degrees soo Height of target km Distance between sensor and instrument m Figure 7 2 The resulting error for azimuth and elevation angles in the function of height of target and distance between sensor and instrument if the direction of instrument is the 1 0 0 or 0 1 0 unit vector from sensor and the set value in SvalPoint for the height of target is 110 km The maximum value for azimuth and elevation errors are 0 4714 and 0 0094 Graph plotted with MATLAB Elevation angle error degrees Do Height of target km Distance between sensor and instrument m Figure 7 3 The resulting error elevation angle in the function of height of target and distance between sensor and instrument if the direction of instrument is the 0 0 1 unit vector from sensor and the set value in SvalPoint for the height of target is 110 km The maximum value for azimuth and elevation errors are 2 5444 e 4 approximately 0 and 0 0047 Graph plotted with MATLAB 45 Figure 7 4 The resulting error for azimuth and elevation angles in the function of height of target and distance between sensor and instrument with the height of target 200 km estimated with 50 km uncertainty Height set in SvalPoint 200 km The maximum value for azimuth and elevation errors are 0 1
14. and the correct feedback is received This is a hazard for program freeze in consequence another condition is added to end the while loop the expiration of a timer started when the control command was sent to the instrument It is however not desirable for the while loop to end with the timer expiration as it takes longer time than the execution of the maximum range of motion by the instrument therefore it is made sure that all erroneous commands are filtered out Erroneous commands might appear in three situations the command word is not recognized the values following the command word are not correct or the instrument cannot execute the motion due to limitations in its motion range 23 In case the command word is not recognized by the server no action is taken For other erroneous cases an appropriate feedback with the words Error in command is sent to the client These cases are e Number expected and something else received Some of the command words expect to be followed by numbers for example the GPS word An example for incorrect command is GPS 7k 5 15 4 500 Note that the decimal separator is the full stop e Values not in range For each number the values are expected to fall in a defined range The geodetic latitude value must fall in the 90 90 range the longitude into 180 180 the altitude of the position and of the target must be positive the azimuth and elevation must be between 0 360 e Re
15. based pointing location calibration errors for the sensor and instrument introduce a decrease in accuracy that is also more visible at close targets This method has however further limitations to consider In the case of the Sval X Camera when an all sky camera is used for target location and no information can be acquired about the range of the target the correctness of the height estimation limits the accuracy See more about it and its effects in Subsection 7 1 Furthermore calculating the range based on the height of target is done with an estimated curvature in prime vertical of the ellipsoid that reduces the accuracy of the calculations The effect of this is the smallest when the target is at 90 elevation angle 42 Errors in target identification may occur in the case of the Sval X Camera when an all sky camera is used for sensor The image often reveals less details close to the horizon increasing the chance for wrong identification of target Considering the aurora supposing that its horizontal feature is of interest its details will be more visible close to zenith than at low elevations 7 1 Calculation of pointing accuracy in relation to error in the height of target As previously discussed in Chapter 5 and in this chapter the determination of the height of target is nec essary in case of direction based pointing To be able to estimate and visualize its importance and effect on pointing accuracy a MATLAB program has been writt
16. by the angles azimuth w and elevation y The components x n y e and z u are sought supposing that v 1 Y Figure 5 6 Calculating the components x or nj y or e z or u of a vector v defined by azimuth w and elevation y Considering Figure 5 6 the following equations can be written y sin y cos 5 11 9 sin w Y cos w Pp PEP 318213 v where p is the projection of vector v in the XY plane Based on the expressions in Equation 5 11 the equations expressing the components of the unit vector are the following ni x cos w cos y ei y sin w cos y 5 12 u z sin y Returning to the problem of the vector magnitude the two control applications offer different targets In the case of the SvalTrack II software the targets are celestial bodies and satellites In the case of the 31 satellites based on the orbital data the range of the vector from instrument to target can be calculated As for the celestial bodies due to their large distance from Earth and due to the relatively very short distance between instrument and sensor it can be safely assumed that they are infinitely far away and parallel pointing is sufficient Therefore the same azimuth and elevation are set on the instrument as given by the sensor It shall be noted that in this case to minimize error the geodetic position of the software shall be set to either the exact same coordinates as t
17. calibration method for fish eye lenses in Pattern Recognition 2004 ICPR 2004 Proceedings of the 17th International Conference on Vol 1 IEEE pp 10 13 KHO 2014a Hyperspectral tracker fs ikea http kho unis no FS IKEA Spesification htm Accessed 2014 07 01 KHO 2014b Narrow field of view scmos cameray http kho unis no sCMOS_Tracker Spesifica tion htm Accessed 2014 07 01 KHO 2014c Practical information about the observatory http kho unis no nordlysstasjon info htm Accessed 2014 07 01 KHO 20144 Related documents http kho unis no nordlysstasjon_doc htm Accessed 2014 07 22 KHO 2014e Tracker camera http kho unis no Track_Camera htm Accessed 2014 07 01 76 Krishnan G amp Nayar S K 2008 Cata fisheye camera for panoramic imaging in Applications of Computer Vision 2008 WACV 2008 IEEE Workshop on IEEE pp 1 8 Mahoney M 2014 Pointing an instrument on an airborne platform http mtp mjmahoney net www notes pointing pointing html Accessed 2014 05 09 Muller R Lehner M Muller R Reinartz P Schroeder M amp Vollmer B 2002 A program for direct georeferencing of airborne and spaceborne line scanner images International Archives of Photogramme try Remote Sensing and Spatial Information Sciences 34 1 148 153 National Coordination Office for Space Based Positioning 2014 Gps accuracy http www
18. camera calibration ssor eoni poeier e a e E E E ee ee 6 3 1 Compensation for spatial displacement o e 6 3 2 The measurements ou oea moe Sh a do PS et eee ae a a Ar T The accuracy of pointing 7 1 Calculation of pointing accuracy in relation to error in the height of target Validation 8 1 Validation planis u 8s 04 4 b a iea a is hoe A aa AA he bo nae 8 2 Pertormed validations Set a AO LR ave daa eo Gee ote a Conclusions The Kjell Henriksen Observatory Tait Bryan angles Calculation of the height of aurora Universal Transverse Mercator coordinate system Fragments from the user manual to the SvalPoint system Et What isSvalPoint a e e Sack oe lk eek ee a a we Ge le Bae A E2 How t use SvalPoint eae ae hon SEE E E oe eS Oe ee Get Bee eed E3 Format of COMMISSION See ee ee ead de ge eed E 4 Known issues and quick trouble shooting 0 00000000000 0004 E 4 1 SvalCast is not responding after the first command was sent E 4 2 SvalCast is not connecting to the servers 2 0 a E 4 3 Target acquisition failed 2 0 00 0 000000 000000200000 E 4 4 Multiple instruments pointing at different targets o E 4 5 Target acquisition stops unexpectedly 2 000000 pe eee Code fragments from server programs 42 43 47 47 48 50 52 55 56 57 List of Figures 1 1 2 1 2 2 2 3 3 1 3 2 3 3 3 4 4 1 4 2 4 3 5 1 5 2
19. each instrument and represents the current location of the unit Once it has been found the variables donea donee boolean are set to true Listing F 7 Function for obtaining feedback from the motor control unit FEEDBACK FROM PTU procedure TPTU46TrackerF ComPort1RxChar Sender TObject Count Integer var newlinepos Integer begin ComPort1 ReadStr ComStr Count TotalCount TotalCount Count Reply Reply ComStr Find new lines and delete them from the read sequence newlinepos Pos String 13 10 Reply while newlinepos gt 0 do begin Delete Reply newlinepos 1 newlinepos Pos String 13 10 Reply TotalCount TotalCount 1 end If the correct feedback is in the sequence of replies indicate that final position is reached if Pos Current Pan position is sAzimuthPSRF Reply gt 0 and home True then begin donea True Reply TotalCount 0 end if Pos Current Tilt position is sElevationPSRF Reply gt 0 and home True then begin donee True gt Reply 74 TotalCount 0 end if Pos Current Pan _ position is 0 Reply gt 0 and Pos Current Tilt position _is_0 Reply gt 0 and donea True and donee True then begin home True Reply 7 TotalCount 0 end end 75 Bibliography Berlin P 2007 Satellite platform design Department of Space Sci
20. from the world reference frame into the local reference frame of each instrument apart doing the same transformations in the opposite direction The algorithm used in the Airborne image mapper software is called Direct Georeferencing the problem being illustrated in Figure 2 1 Point P is the point identified in the image taken by the camera this being the four corners of the picture in the program P is the point sought that in reality of which the image is taken through the focal point The local level coordinate system placed in the focal point of the camera is noted by X Y Z1 while the world reference frame is X2Y2Z2 see Figure 2 1 The position of the point in reality u represented in world reference frame X2Y2Z2 is p Up v HA DCM v 2 1 where v is the position of the local coordinate system s origin in the world coordinate system A is a scale factor specific for the lens used relating P to P DCM is the direct cosine matrix for the rotations that transform a vector in the local reference frame into the world reference frame and v is the position of point P in the X1 Y Z coordinate system 11 gt Ya X Figure 2 1 Illustration of the problem solved in the airborne image mapper software Image adapted from Sigernes 2000 Furthermore expressing the terms of Equation 2 1 Ti vi Yi 2 2 f where x and y are the two Cartesian coordinates of point P in the image f
21. instruments The pitch and roll angles have been measured with a digital level as accurately as possible resulting in the values 0 4 and 0 7 respectively However at later stages of testing it has turned out that these values have not been precise enough Moreover at the time of the calibration there has been a mistake in the code that limits the precision of the camera movement These are the possible reasons for offset appearing in pictures Despite these problems the results for the yaw are fairly correct as shown later in Chapter Figure 6 2 shows the map of the target upon which the first calculation has been made The yaw of the instrument has been initially approximated to be 32 Pictures of the target have been taken with different settings for initial yaw with the aim of finding the angle that results in the target being in the centre of the image upon the execution of command See Figure 6 3 for the images with 26 28 and 30 initial yaw settings The second and third targets are chosen as shown in Figure 6 4 and Figure 6 5 As the targets are in the centre of the pictures no further adjustments are needed 35 Coordinates UTM33X E512600 N8685860 ve UTM35X E241300 N8711190 Des DD DDDD 78 2458 N 15 5542 E Zo DDMM MM 78 14 75 N 15 33 25 E y LON DDMMSS 78 14 44 N 15 33 15 E reen A 4 Larsp lod r 2 A PS ad Des QT SC A Y E ice A Figure 6 2 The first targe
22. is physically impossible due to view field problems One can draw the conclusion that if the sensors are at the same level further errors in elevation are eliminated Furthermore the placement of sensors in the North East plane do not make any difference The maximum error in angles are 0 4714 for azimuth and 0 0094 for elevation These are worst case scenarios without any attempt of determining the height of the aurora having a constant 110 km set the most frequent height of aurora according to Kaila 1987 and Figure 7 1 Considering a more realistic scenario the sensor and instrument are placed at zs Net 0 direction Note that the North East coordinates do not make difference as concluded earlier however they are levelled for the best possible results The height of target is determined to be 200 km with 50 km uncertainty For the graph in Figure 7 4 the height of the target set in the SvalPoint is 200 km resulting in the errors 0 1081 in azimuth and 0 0022 e in elevation As one may see the error in pointing is larger if the 44 target is lower than the estimated height therefore one may conclude that performance may be maximized if a lower value is entered for the height in the SvalPoint system to balance the errors It has been found that in this case the value 187 km is the height of target value that results in the lowest error in pointing for the 150 250 km range 0 0873 in azimuth and 0 0017 e 4 in elevation See
23. is the focal length of the lens and 1 0 0 cos 0 0 sin 0 cos y sin y 0 DCM 0 cos c sin o 0 1 0 sin W cos w 0l 2 3 0 sinlo cos c sin 0 0 cos 0 0 1 where g 0 and y are the roll pitch and the yaw angles respectively for the attitude of the local coordinate system in relation to the world reference frame See also Muller et al 2002 The equations presented are adapted to the SvalPoint system see Chapter 5 12 2 2 Sval X Camera The Sval X Camera is a software developed at UNIS that collects image feed from any camera connected to the computer given that its driver is installed and it has DirectShow application programming interface API The software contains numerous functions for video and image processing such as tracking of an object in the video or summing up a user defined number of frames to get a sharper and more clear image of a static object The program is used as a possible user interface for control in the SvalPoint system with minimum modification One of the functions in the control interface of Sval X Camera is the video overlay for all sky cameras This overlay indicates the cardinal directions in the image in addition to showing the line of horizon The necessary attitude and position information for this overlay may come from both a gyroscope GPS pair as dynamic values or can be static calibration inputs It also calculates the direction to a target identified by a click on the im
24. observations not possible before at the observatory 1 2 Task analysis To meet the goals defined in Section 1 1 the main problems to be solved in the projects are design of the system as a software package what are the functionalities of different applications working together description of the new programs that need to be developed definition of control methods for the instruments how is the target defined what is the information needed about it design of the connections between the programs used communication protocols and the definition of high layer protocols development of algorithms controlling the instruments for each of the defined pointing methods definition of calibration parameters and methods Regarding the instrument control problem the pointing is done by the operation of two motors The con trol of their motion is done by azimuth and elevation angles from the spherical coordinate system Motor controller units are connected to each pair of motors therefore their control is possible by command words sent on serial ports making the extent of this work to be that of high level logical control The tasks at hand are finding optimal solutions to the problems listed above the implementation of the new programs calibration of the system performance evaluation validation of SvalPoint During the practical work related to this thesis the software development and the solving of the problems are done in
25. of the Watec LCL 217HS colour and the Watec 902B monochrome camera on a PTU D46 unit The lenses used are 30 mm Computar TV Lens with a relative aperture f 1 3 for the colour camera and a 75 mm Computar lens with f 1 4 for the monochrome camera This instrument is used to provide a live feed on the internet at the KHO web page KHO 2014e See Figure 3 3 for an image of the Tracker Camera and the PTU D46 unit 17 A B Figure 3 3 The PTU D46 platform Panel A Example for the use of the PTU D46 unit at KHO the instrument Tracker Camera The Watec LCL 217HS is mounted on the top while the Watec 902B is the bottom camera Panel B The PTU D46 unit with its motor controller Image from Directed Perception 2007 3 2 Sensors 3 2 1 All sky camera The all sky camera at KHO is constructed of a DCC1240C HQ C MOS camera from Thorlabs and a Fujinon FE185C046HA 1 fish eye lens See Figure 3 4 According to Fujinon Fujifilm 2009 the lens has equidistant projection f0 system see Equation 2 4 a focal length of 1 4 mm and a field of view of 1851 The camera has a resolution of 1280 x 1024 Pixels and a sensitive area of 6 78 mm x 5 43 mm see Thorlabs 2011 Figure 3 4 The all sky camera Panel A The all sky camera at KHO with its lens cover off The ring around the lens with the spike is a sun blocker to avoid direct sunlight on the sensor Panel B The DCC1240C HQ C MOS camera Image from Thorlabs 2011 Panel C Th
26. parallel by exploring possibilities trying out methods identifying necessities An additional problem to be solved is that of work arrangements due to the remote location of the obser vatory A test system using a pan tilt unit mounted on a tripod pointing a web camera has been installed at UNIS therefore the need for visiting KHO during the implementation and testing of the algorithms is eliminated See the sketch of the system in Figure 1 1 Camera Pan tilt unit Tripod Figure 1 1 Sketch of the test system used for the implementation of the pointing algorithms 1 3 Outline of Thesis This thesis presents the software applications that form the SvalPoint system and their interaction The protocols and algorithms used for the pointing control of the instruments is presented in detail being the major contribution of this project apart from the definition and creation of the system Furthermore the calibration processes related to the system are also described in addition to the validation and conclusions about the system Chapter 2 presents projects that precede SvalPoint conducted at UNIS The first section describes a soft ware solving similar coordinate system change problems as the ones met in this project Lastly the second and third sections describe the programs used in the SvalPoint as user interfaces for target acquisition In Chapter 3 the reader will find a description of the hardware used in SvalPoint Some terminology u
27. still contain the target One can draw the conclusion that chance for the success of the pointing decreases with the increase in the size of the target The second large factor limiting the accuracy to be considered is the pointing algorithms of the instruments Three major limitations shall be considered calibration inaccuracies the accuracy in the target location and the accuracy of target identification The inaccuracy in the initial instrument attitude coming from calibration errors affects all modes of instrument control When transforming the vector from its representation in the Instrument World Refer ence Frame IWRF to a representation in the Pointing System Reference Frame PSRF as the PSRF is calculated by the roll pitch and yaw angles the direction will be offset with as much as the error in these angles This results in effects and further discussion identical to the motion resolution problem presented earlier In the case of geo pointing considering that the positioning of the instrument and target is exact the pointing is more accurate than the resolution of the motors limited only by the accuracy of real number representation in the computer The source of inaccuracy lies in the exact positioning of both instrument and target Considering inaccurate acquisition of location data for target and or instrument the direction of pointing will experience larger error at shorter instrument target distances In the case of direction
28. the instruments while the server sends a feedback to the client about the success of the execution of commands The protocol for messages sent by the client to the server is based on command words to indicate different ways of control The protocol is based on strings following each other in separate messages There are five command words Some are stand alone basic commands while others must be followed by different values in a given order The commands are as follows e HOME alternatively home or Home The keyword HOME sends the instrument to its home position defined as home positions for the motors This command is not followed by any value Note that this position is not equivalent to sending 0 azimuth and elevation values to the instrument e GPS alternatively gps or Gps The keyword GPS must be followed by 3 numbers in the following order geodetic latitude in degrees geodetic longitude in degrees and altitude above reference ellipsoid in metres Through this command the target of pointing is defined through its geodetic coordinates Note that the convention is negative values for East and South Example GPS 78 15 16 02 445 e AZEL alternatively azel Azel or AzEl The keyword AZEL must be followed by five values representing the geodetic location of the sensor latitude in degrees longitude in degrees and altitude above reference ellipsoid in metres and the azimuth and elevation angle for the direction vector to the ta
29. the pitch and roll the camera is pointed at different targets and with trial and error method the angles are adjusted until the target is in the centre of the picture However as there are two angles to change and their effect on the pointing is not straightforward it is not an effective or very precise process However as the camera is not used for gathering scientific information the requirement for the precision of pointing is not that high As long as the target is in the picture it is considered satisfactory In the case of the all sky camera the same approach is used only that a calibrated instrument is pointed by the use of the Sval X Camera control interface The angles are adjusted until the instrument records images of the target selected in the sensor s picture 6 3 All sky camera calibration The lens of the all sky camera is a Fujinon FE185C046HA 1 fish eye lens According to Fujinon Fujifilm 2009 it has an equidistant projection see Equation 2 4 a focal length of 1 4 mm and a field of view FOV of 185 However when these parameters are used the resulting FOV is over 200 In consequence two verifications are done for the lens verification of the FOV especially in the light of Krishnan amp Nayar 2008 stating that after calibration the FOV for this lens has been found to be 194 and the equidistant projection equation is suspected to have a scaling factor that needs to be determined please refer to Section 2 2 for
30. the string is one of the command words If it is not no action is taken If the string matches a command word depending on each case other strings might be read from the client The cases are marked by visible comments in the code for readability In this fragment the Home and End commands are shown together with a direction based pointing command AzEl The other pointing commands acquiring target are similar therefore not explained See Section 4 2 3 for more details on the command protocol Upon the Home command the TP and PP strings are sent to the unit the keywords that move the tilt and pan motors in their home position On the End command the TCP connection between the client and server is ended The actions on AzEl command are the calculation of the pointing direction the control of the instrument and the sending of feedback to client All steps for the transformation of input information into degrees of azimuth and elevation for the instrument in the PSRF are clearly marked See Chapter 5 for further details The next step is to adjust these angles to the values that need to be sent on the COM port taking into account the command format of each instrument In the case of the PTU D46 the sign of the number defines the direction of motion referenced from the home position of the motors A negative number moves the unit to the left and up while the positive number moves it to the right and down Moreover the motors are comma
31. 081 and 0 0022 Graph plotted with MATLAB Figure 7 5 The resulting error for azimuth and elevation angles in the function of height of target and distance between sensor and instrument with the height of target 200 km estimated with 50 km uncertainty Height set in SvalPoint 187 km The maximum value for azimuth and elevation errors are 0 0873 and 0 0017 Graph plotted with MATLAB 46 Chapter 8 Validation The complete validation of the system includes the testing of the connections and the testing of the pointing itself It is done in order to ensure that the system can be used to perform the tasks that it was designed for fulfilling all aims of the project 8 1 Validation plan For validating that the SvalPoint system is working from the connection s point of view the following tests shall be done ls connect to all combinations of the possible servers e g connect to Fs Ikea Tracker and Keo Sky Scanner but not the PTU46 Tracker making sure that they respond correctly try connection with the firewall blocking all attempts to connect then from a computer that is not in the exception list making sure that the connection is declined in both cases connect and disconnect repeatedly with the client application making sure that new connection is possible after each disconnection try connecting the client to servers that are not connected to the internet making sure that the failure to connect is properly i
32. 20140 16 3 1 2 Hyperspectral tracker Fs Ikea The Hyperspectral tracker is a narrow field of view hyperspectral pushbroom imager The instrument composes of two parts an all sky scanner and a spectrograph see Figure 3 2 Sky Scanner 2 gt Se Led i Figure 3 2 Panel A The Fs Ikea spectrograph with its protective covers off 1 Front lens 2 Slit housing 3 Collimator 4 Flat surface mirror 5 Reflective grating and 6 Camera lens Panel B All Sky scanner Image from KHO 2014a The spectral range of the instrument is between 420 and 700 nm with a bandpass of approximately 1 nm The exposure time for one spectrogram is approximately 1 s One of the possible lenses to be used is a Carl Zeiss Planar 85mm ZF with the relative aperture f 1 4 The all sky scanner is composed of two first surface mirrors mounted on two stepper motors The azimuth range of the instrument is 360 while the zenith angle range is 90 The resolution of the motion is 0 0003 with an accuracy of 0 05 See more at KHO 2014a 3 1 3 Instrument constructed on the PTU D46 platform The PTU D46 is a pan tilt unit suitable to point any instrument weighing up to 1 08 kg in a range 159 in azimuth and 31 down and 47 up in elevation with resolution of 0 0129 Directed Perception 2007 This unit is used widely at KHO mainly pointing cameras with different lenses One example for its use is the Tracker Camera a mount
33. A The DGPS station placed over the marked location in Svalbard nearby KHO Panel B The centre of each dome on the roof of the observatory is measured with the user equipment communicating with the DGPS reference station that uses the GRS1980 ellipsoid therefore that is the standard used for this transformation Each dome has been numbered and measured during the process The measurements of the domes of inter est in this project are the ones housing the Narrow Field of view sCMOS camera referenced as Keo in the followings the Fs Ikea and the all sky camera PTU D46 unit pair See the values and their equivalent in Geodetic coordinates in Table 6 1 Note This value represents the centre of the dome For the centre of the instrument lens further spacial offset measurements shall be done Due to delays in the delivery of the measurement data all tests of the system has been done based on data acquired with a hand held high precision GPS device available at KHO Table 6 2 shows the values for each instrument These measurements have also served as a verification on the transformation results In conclusion the measurements are fairly consistent between the DGPS and hand held GPS methods The largest error is for the Fs Ikea instrument East coordinate however it is fairly straightforward from the pattern of the values the hand held device measurement was of low accuracy It shall be noted that the DGPS measurements may be further refined consi
34. AzEIPSRF az RadToDeg AzEIPSRF az AZEIPSRF el RadToDeg AzEIPSRF el Calculate elevation viewangle degrees in direction nElevationPSRF round AzEIPSRF el if nElevationPSRF gt 0 then Calculate azimuth and elevation commands AzEIPSRF el AzEIPSRF el else errorinCmd True Instrument is incapable of pointing downward Calculate azimuth degrees for instrument with direction nAzimuthPSRF round AzEIPSRF az if nAzimuthPSRF gt 90 then begin 72 end 7 AzEIPSRF az 180 AzEIPSRF az AzEIPSRF el AzEIPSRF el end else if nAzimuthPSRF lt 90 then begin AzEIPSRF az 180 AzEIPSRF az AzEIPSRF el AzEIPSRF el end else AzEIPSRF az AzEIPSRF az Print angles for instrument Str AzEIPSRF az sAzimuthPSRF Str AzEIPSRF el sElevationPSRF memol lines add Azimuth angle sAzimuthPSRF memol lines add Elevation angle sElevationPSRFE Calculate number of steps elevation nElevationPSRF round AzEIPSRF el TR Calculate number of steps azimuth nAzimuthPSRF round AzEIPSRF az PR Set az and el on instrument if Comportl Connected then if nAzimuthPSRF lt PX and nAzimuthPSRF gt PN and nElevationPSRF lt TX and nElevationPSRF gt TN then begin Calculate the motion needed save current spot nAzimuthPSRF_C nAzimuthPSRF CAs nElevationPSRF_C nElevationPSRF
35. OS Phase 52 54 a 72 THEOS Orbal Data e Elevation 4 48 74 YAOGAN 4 Azimuth 191 65 T 75 YAOGAN 5 Time 05 07 2014 17 49 04 Up PEL YAOGAN 6 Epoch min 1908828 96 77 RAZAKSAT First Quarter 78 DEIMOS GEO Position km 79 OCEANSAT 2 7 80 WORLDVIEW 2 Latitude 78 358 N in 81 SMOS Longitude 132 771 E 7 E B2 YAOGAN 7 E Alitude 624 071 km Elevation 19 86 63 YAOGAN 10 Velocity 7 543 km s Azimuth 286 23 Ms Rise NA Twotine Elements Sets TLE Latitude 78 148 N Set NA File resource txt Ca E Tronk NA A itude 531m a FF Display al iole Azimuth 31 75 Condon Day Elevation 5 32 TLE Element Position tatus 7 COSMO SKYMED 3 T Coordinates 1334120 08054A 1032216674212 00001217 00000 0 14637 3 0 2795 78 148 N 16 039 E 2 33412 97 8609 147 0081 0001170 85 6695 274 4618 14 82164140111705 Site Date 05 07 14 GST 190 919972 Time 17 47 23 UT Figure 2 3 The graphical user interface of the SvalTrack II software 15 Chapter 3 SvalPoint Hardware The hardware of the system contains two types of units computers and different instrumentation Each instrument has its dedicated computer for its control and the acquisition of data from it One of the computers acts as the controller of the SvalPoint system that can be separate or one connected to an instrument The instrumentation falls in two categories from the SvalPoint s point of view Instruments and Sensors The instruments ar
36. accuracy of GPS in normal operating conditions See also National Coordination Office for Space Based Positioning 2014 DGPS is based on computation and correction of range error for each GPS satellite in the view of a single reference station placed at a known location In the case of Svalbard these locations are marked by a concrete platform with a metallic bullet in its centre Then the corrections are transmitted to the nearby users improving the accuracy of the measurements made by them It shall be noted however that as the distance between reference station and user increases the lines of sight through the ionosphere and troposphere changes resulting accuracy degradation as the delay to the station and user are different See Figure 6 1 for photos of the measurement process on sight 6 1 2 The measurements The formulas that transform from Transverse Mercator Projection into geodetic coordinates are named the inverse Gauss Kriiger projection To perform the transformation a MATLAB function is used from the toolbox Wasmeier 2006 The function is named utm2ell denoting transformation from UTM to ellip soidal coordinates taking into consideration the irregular sections see Appendix D for more information about the irregular sections In the input there is an option of entering the standard for the ellipsoid that is implemented in the same toolbox as data structures The DGPS measurements are done in ETRS89 33 Figure 6 1 Panel
37. age defining the azimuth and elevation angles for that point from the origin of the lens coordinate system placed in the optical centre of the lens aligned with the direction of the axis of focus The values are later transformed into a local level world reference frame placed in the centre of the lens aligned with north east and up directions making the direction of target independent of the orientation of the camera the only dependency remaining its geodetic location These calculations give information about the location of target used for the control of instruments In the followings the method for calculating the angles in the lens coordinate system is presented Considering a fish eye lens that all sky cameras use Figure 2 2 can be drawn with two coordinate systems associated with the camera the coordinate system of the lens noted by X Y Z and the coordinate system of the image plane X2Y2Z2 The focal length of the lens is f The aim is to define the direction to P point in the real world based on the position of P point in the obtained image indicated in Figure 2 2 The position of P can be determined in the image by the values r the distance between P and the centre of the image coordinate system and 43 angle between axis Y2 and r The direction of point P in X YZ shall be defined by the direction of vector p in spherical coordinates According to Kannala amp Brandt 2004 the fish eye lenses are usually des
38. all be noted that none of the current control interfaces point the instruments by the use of geodetic coordinates At the moment this feature is used only in calibration The chosen language for the implementation of the applications is Delphi for a number of reasons Foremost all other programs associated with the control of the instruments developed at KHO are in Delphi making it the first choice due to considerations of program extension maintenance or future changes Another reason for choosing Delphi is that the applications require a graphical user interface that is tedious to develop in many languages in contrast to Delphi Delphi has been developed with the aim of providing a rapid application development RAD software based on a set of intuitive and visual tools that help the programmer The user interfaces are constructed visually using a mouse rather than by coding that greatly helps in visual interface development Moreover Delphi offers object oriented programming based on Pascal with its own integrated development environment IDE The IDE also implements a debugger offering options for setting breakpoints in the code step by step running and the display of the values of variables all helping the program development 20 process greatly 4 2 Communication between programs The applications defined in Section 4 1 shall be connected among each other to be able to transfer the required data Two types of connections are needed
39. and the server applications have been implemented during the time span of the thesis work Due to the complexity of the system a User s Manual provided that introduces the reader to the system compiling all information needed for the use of the software package and to support the future maintainer of SvalPoint See Appendix E for fragments of the user manual The current system is capable of pointing 4 instruments installed at KHO at the same time counting the test instrument used for development not installed on a fixed platform The instruments may be picked in any combination and only the selected ones are commanded The scientific data collection is not part of the system standalone programs are developed for them The theoretical accuracy of SvalPoint is limited only by the motion accuracy of the individual instruments However in practice the following factors influence the pointing accuracy precision of calibration human factor at the selection of target in the control interface and the accuracy of the target s height determination During the time of the thesis only partial validation has been possible due to light conditions and technical difficulties at KHO The complete validation and trial of the competence of the system for the required observations is to be done in the up coming auroral season After the first observations the ease of use for the system is to be assessed and modifications may be done to the user interface or soft
40. and roll angles there is dedicated equipment available a high precision level For the yaw calibration however the geo pointing is used It shall be noted early on that as the coordinate systems used are left handed the sign of the angles is as follows yaw angle is positive from North towards East pitch angle is positive in the direction from horizontal to down and roll is positive in the direction from right to left 6 2 1 Yaw calibration To define the yaw the offset from North shall be determined The Geo pointing is used for this procedure Assuming that the location of the instrument is correctly determined and that the pitch and roll angles are correctly measured by pointing at known locations the yaw angle input can be adjusted until the picked points appear in the centre of the image taken by the instrument The calibration points shall be picked in a way that the features are easily recognised in the image e g mountain tops or distinctive features of the shore The process shall be done for several points followed by the calculation of a mean value for the resulting yaw angles In case the difference between the calibration points is unacceptably large e g in the order of 107 the location pitch and roll calibrations shall be revisited In the followings the calibration for the Tracker Camera is shown It shall be noted that at the time of the calibration only hand held GPS measurements have been available about the location of the
41. as also been a rounding mistake in the geo pointing feature of the software used as the basis of the calibration that has limited the accuracy of the pointing effecting the initial yaw measurement on both instruments In conclusion the calibration 48 l f Ros 4 y doo r D de NN Figure 8 1 Images taken during the validation of the system The images are recorded as follows from left to right image from the all sky camera as sensor the red cross in the yellow circle marking the target of pointing image recorded by the Tracking Camera image acquired by the Narrow Field of view sCMOS camera image upside down and mirrored due to the reflections in the flat surface mirror assembly On both images acquired by the instruments the orange cross marks the centre the blue lines mark the centre of the image from the other camera and the red circle marks the target of pointing values have been more inaccurate in this instance then they will be in the future However as the Tracker Camera unit is not an instrument of interest but has been used only for testing and the target is still in the field of view and since the Narrow Field of view sCMOS camera has a pointing accuracy considered satisfactory the re calibration has not been done and the test has been considered passed Summarizing the sources of errors in both units the following factors are relevant in decreasing order of their estimated magnitude e Narrow Field of view
42. ast on is a KHO computer Check that the SvalCast is launched only once on the computer as if another instance is running that occupies the port If this was not the cause of the problem check that the Server programs are all running and connected to the internet This might be the most probable cause if only some of the servers fail to respond Also verify the IP address and the Port number both in the Server applications and the SvalCast Verify firewall settings on the server computers to make sure that connections are allowed If all else failed try restarting the server programs E 4 3 Target acquisition failed In case the target acquired is incorrect the most probable issue is calibration Check the Calibration section of the User Manual for more information on how to calibrate each instrument and update the parameters E 4 4 Multiple instruments pointing at different targets The first thing needed to be done is to check that the height of target information is set in this case In the case of the Sval X Camera software 0 km height means infinite distance therefore the instruments point parallel In case you have information about the height of the target enter it in km in the dedicated dialogue box If this does not solve the problem verify the calibration data of the instrument that points in the wrong direction Note The accuracy of pointing is determined by many factors It is worse at lower altitudes and at lower accuracy of determi
43. at getlat sInCommand sInCommand AContext Connection Socket ReadLn lon getlon sInCommand sInCommand AContext Connection Socket ReadLn alt getalt sInCommand sInCommand AContext Connection Socket ReadLn az getaz sInCommand sInCommand AContext Connection Socket ReadLn el getel sInCommand If all inputs are correct if errorinCmd False then begin 71 Set the new azimuth and elevation value in the AzEIWRF AzEIWRF az DegToRad az AzEIWRF el DegToRad el Set sensor coordinates Sensor lat DegtoRad lat Sensor lon DegtoRad lon Sensor alt alt Set instrument coordinates HomeC lat DegtoRad lath HomeC lon DegToRad lonh HomeC alt alth Calculate vector based on n e and u components neuSWRF AzEITONEU AzEIWRF Target infintely far away IWRF SWRF neulWRF 0 neuSWRF 0 neuIWRF 1 neuSWRF 1 neulWRF 2 neuSWRF 2 Transform from IWRF to PSRF translate and rotate vector neulWRF 0 neulWRF 0 xoff neulWRF 1 neulWRF 1 yoff neulWRF 2 neulWRF 2 zoff neuPSRF RotateToPSRF neulWRF Calculate azimuth and elevation from neu the result is not real elevation viewangle AzEIPSRF NEUToAzEl neuPSRF Change angles into degrees Note the elevation is actually the viewangle For the FS ikea the command is based on the viewangle
44. ature of the differences between server programs In contrast with the same command implementation for the PTU D46 one may notice that the way of calculating the direction vector is identical only in the determination of the actual commands changes The Fs Ikea instrument has a different protocol for the commands than the PTU D46 The azimuth motor moves only 90 to each side while the elevation motor moves 180 to ensure whole sky visibility Another difference is that the control of this instrument is not absolute but always referenced to its current position making it necessary to keep track of it in the CAs CEs Integer variables Furthermore there is no option on this instrument to make an inquiry of the current position Therefore a waiting function is used Procedure WaitOnMotors Steps integer implements a delay based on the number of steps that the unit will take It takes into consideration the acceleration nominal speed and deceleration of the motor calculating the time needed for the motion to be executed Listing F 6 Function fragment illustrating the difference between the different server programs Azimuth and Elevation command Receives lat lon alt az el if smCommand AzEl or sInCommand AZEL or sInCommand azel or sInCommand Azel then begin errorinCmd False New commands Read commands in order sInCommand AContext Connection Socket ReadLn l
45. cific all sky camera with the used sensor as the sensor has not been previously calibrated on its own 41 Chapter 7 The accuracy of pointing The system is planned to be used for various observations for various targets the main focus being aurora Due to the very dynamic nature of the phenomenon and the large variety of its shape size and location in the sky also due to the differing nature of scientific observations there could not be a well defined accuracy requirement from the start ultimately aiming for having the target in the field of view of the instrument The system involves many processes that contain both human factor and a multitude of possibly standing cases contributing to the accuracy of pointing noting that errors may propagate ultimately and they shall be reduced as much as possible in all cases Therefore the problem is discussed in terms of absolute limi tations and conditions that change the final accuracy The first and most important factor in the accuracy is the resolution of the pointing control motors This limits the finery of the motion and therefore sets an absolute technical limit on the accuracy of the point ing The values for the different instruments are to be found in Chapter 3 On the other hand since the instruments are not sensing with a single pixel but have a field of view some displacement may be permitted considering the size of the target and nature of observation as the image acquired might
46. culate the vector in global level Cartesian coordinates in the coordinate system XYZ with its origin in the centre of the Earth Finding this vector is a subtraction operation once we know the coordinates of the two points in Cartesian representation The vector found then is to be represented in the local reference frame IWRF Therefore the first problem that needs to be solved is the finding of the Cartesian coordinates of a point based on the geodetic coordinates see Figure 5 1 Figure 5 1 Illustration of Cartesian coordinates X Y Z and geodetic coordinates y A h Figure adapted from Hofmann Wellenhof et al 2001 26 According to Hofmann Wellenhof et al 2001 the relations for these calculations are X N h cos y cos A Y N i cos y sin A 5 1 Z N n sin y where N is the radius of curvature in prime vertical obtained by the relation 2 N A 5 2 E a2cos y bsin p and a b are the semi axes of the ellipsoid The parameters of the ellipsoid that models Earth are defined in numerous different standards such as the World Geodetic System WGS 84 the European Terrestrial Reference System ETRS 89 or the North American Datum NAD 27 and NAD 83 just to mention but a few These standards use different reference ellipsoids The coordinates for the target might be acquired with two methods using maps or using GPS system The mapping in Europe is done based on the ETRS 89 while GPS
47. d Manager of Windows That happens each time an exception is thrown and it is not verified and treated in the code The connections between programs throw a large number of exceptions e g the client is not responding the connection cannot be established therefore a special emphasis is placed on their treatment during the development of the software applications 21 The security of the system is mainly ensured by the firewall on the computers blocking any attempts for connection coming from another computer than one registered in the KHO network The security related considerations implemented in the servers are the verification of command formats and values 4 2 1 TCP socket The TCP socket is the endpoint of inter process communication flow based on internet protocol between server sender of data and client receiver of the information The client application establishes point to point virtual connection also known as TCP session between two sockets defined by IP address identifying the host interface and port number identifying the application and therefore the socket itself The server applications create sockets that are listening and responding to session requests arriving from clients An internet component suit in Delphi 5 is provided by Indy Internet Direct in the form of a Visual Component Library VCL The Indy Sockets includes client and server TCP sockets and it has been used in the implementation of all servers and the c
48. d further enhance accuracy without causing the operation to be significantly more complicated 51 Appendix A The Kjell Henriksen Observatory Figures A 1 A 2 and A 3 show details of the KHO building The pictures are presented to help the better understanding of the need for the system and the motivation for different aims and desired features of SvalPoint Basic design A The Kjell Henriksen Observatory KHO SS SS SG 2 5 B Standard Instrumental module Figure A 1 Basic design of the observatory with a drawing of the standard instrument module Image from KHO 2014d 52 ON PLATFORM Telemetry Station Nobile Amundsen Stratospheric Ballon Center Italian Space Agency a gt F E 2 3 Spectrometer UNIS 1m Silver Bullet Telescope UNIS Auroral Radio Spectrograph Tohoku University 100m gt MEN 2 axis Search coil Magnetometer Augsburg College and University New Hampshire 100m HF Acquisition system Institute of Radio Astronomy GPS antenna FMI In addition 1 64 beam Imaging Riometer Danish Meterological Institute Old station Adventdalen 2 Ceilometer AVINOR Calibration platform at UNIS Figure A 2 Fragment of the map of KHO showing allocation of instruments with the focus on the facilities located in the service section of the building Note the operational room marked with operasjonsrom Image fr
49. d west extremities appear distorted however there is no distortion along the meridian that is tangent to the cylinder showing true distances The zone around the meridian considered still sufficiently little distorted is 3 in each direction resulting in 6 wide portions for the system dividing the Earth in 60 longitudinal mapping zones See also Hager et al 1992 Figure D 1 Illustration of the UTM CM Central Meridian AB DE Lines of secancy formed by the intersection of cylinder and ellipsoid Image from Hager et al 1992 The Universal Mercator Projection modifies the cylinder of projection by reducing its elliptical dimensions and making it secant to the ellipsoid It results in intersecting the ellipsoid along lines parallel to the central meridian See Figure D 1 In one 6 zone the lines of secancy establish approximately 180000 m east and west from the central meridian The effect of these lines of secancy is that of allowing a more 57 consistent relationship between ellipsoid and map distances resulting in a scale factor of 0 9996 for the conformal coordinates in the plane See Hofmann Wellenhof et al 2001 Hager et al 1992 The grid zones are defined uniform over the globe however as shown in Figure D 2 there are exceptions to this rule in the Scandinavian region the south west coast of Norway and the area of Svalbard Around Svalbard there are four grid zones 31X 33X 35X and 37X are extended to width
50. de and they are responsible for the calculation of pointing direction for each instrument based on the information received from the client Before discussing the implementation of the different pointing modes a set of reference frames is to be defined for the system e The Sensor World Reference Frame SWRE is defined as a Local Level Coordinate System associated with the sensor This is the coordinate system in which the commands from the client application are received in case of direction based pointing command It is a left handed coordinate system X axis is aligned with True North referenced to as N Y axis with East referenced to as E and the Z axis with Up referenced to as U Its origin coincides with the centre of the sensor lens or in case of a mathematical control interface the origin is the point specified as point of observation in the application e Another Local Level Coordinate System referred to as the Instrument World Reference Frame IWRE is defined This reference system is identical with the SWRF in all aspects but one its origin coincides with the centre of the instrument s lens A vector in this reference frame shows the direction in World Coordinates where the instrument shall point to acquire an image of the target e The Pointing System Reference Frame PSRF is the reference frame in which the instrument is controlled The origin of this coordinate system is in the intersection of the two axis along which the
51. dedicated to the instrument For the conduction of the observations there is a separate operational room of 30 m large enough to house a number of work stations therefore suitable for a group of people to work comfortably at the same time See more information on the KHO building in Appendix A and at KHO 2014c One of the problems desired to be solved is the need of personnel in the control rooms The new system shall make it satisfactory to sit only in the operational room or alternatively to work from Longyearbyen as the travel to KHO due to its location is not possible by car but only by belt wagon or snowmobile during the observational season The second problem seeking solution is the acquisition and position determination of targets An intuitive easy solution is desired with multiple options easily adapted to future needs There are a number of software applications already developed at The University Centre in Svalbard UNIS that are suitable for target location such as the Sval X Camera and SvalTrack II see Sections 2 2 and 2 3 for more information on the programs These applications shall be integrated in SvalPoint as user interfaces for finding and locating the target An additional goal for the system is to enable simultaneous control of multiple instruments possibly installed at different locations pointing them at the same target hence acquiring the name multi track optical pointing system This will enable a large range of
52. dering that all domes have the same height the difference in it coming from the position of the user device that might have been not perfectly vertical at times or might have been placed not exactly in the centre of the domes Calculating the mean value of all heights measured on all domes on the top of the observatory the result is 523220 mm value used in the calculation of error for the measurements with the hand held GPS device 34 Table 6 1 DGPS measurements and their equivalent in geodetic coordinates Instrument UTM coordinates Geodetic coordinates North m East m Height North East Height mm mm Keo 8675070 729 523835 847 523470 78 14775385 16 03963733 523470 Fs Ikea 8675068 108 523831 084 523455 78 14773113 16 0394276 523455 PTU D46 8675062 921 523821 632 523161 78 14768616 16 03901141 523161 Table 6 2 Geodetic coordinates of instruments measured with hand held GPS device Instrument Geodetic coordinates Error North East Height North m East m Height mm mm Keo 78 14776 16 0396075 520000 0 00000615 0 00002983 322000 0 696 0 674 Fs Ikea 78 1477 16 0389 520000 0 00003113 0 0005276 322000 12 034 3 688 PTU D46 78 147686667 16 03900667 520000 0 000000507 0 00000474 322000 0 11 0 054 6 2 Home attitude determination of the instruments and sensors For the calibration of the pitch
53. determining the heigh of the aurora it shall be noted that all these observations are complex therefore take time possibly not comparable with the dynamics of the phenomena In case any of the options is to be used a well automated process is at need On the other hand depending on the precision needed for the observations a fairly good guess about the height might be sufficient See the induced angle errors by imprecision in height in Section 7 1 56 Appendix D Universal Transverse Mercator coordinate system The Universal Transverse Mercator UTM coordinate system uses two dimensional Cartesian coordinates to define locations on the surface of Earth It is the preferred system for large scale mapping 1 250000 and larger scales giving the advantage of simple numbers over the complex degrees minutes and seconds of latitude and longitude For more details consult Terry Jr 1996 As described in Hager et al 1992 as well the Mercator Projection can be visualised as an ellipsoid projected into a cylinder tangent at the equator and the polar axis coinciding with the axis of the cylinder Opening and flattening the cylinder results in distortion at the polar regions while the showing true distances along the Equator The Transverse Mercator Projection is a Mercator Projection with the cylinder rotated by 90 resulting in the ellipsoid and cylinder being tangent along a meridian In this case when the cylinder is flattened the east an
54. e Fujinon FE185C046HA 1 fish eye lens Image from Fujinon Fujifilm 2009 1The field of view has been found to be 194 during calibration 18 Chapter 4 Software design The design of the system as a collection of software applications the scope of each program and their interaction is one of the main contributions of this thesis The final structure has been defined well in the development of the software by identifying needs and trying out different alternatives The end result of this process is presented in this chapter 4 1 System definition The aim of SvalPoint is to fill in the existing gaps in the current process of instrument operation The system shall provide easy options for target location and acquisition and link it to the pointing of the instrument eliminating the necessity for presence in the control room see Section 1 1 for the complete description of project aims The acquisition of data from the target instruments is already automated solved for each instrument apart independent of the SvalPoint system The SvalPoint system is composed of three parts e acontrol interface which can be any of the two already existing applications developed at KHO SvalTrack II or Sval X Camera with the responsibility of acquiring the target and determining its location e server programs dedicated to each instrument and installed on the computers in the control room with the responsibility of pointing the instrument deve
55. e in SvalPoint for the height of target is 110 km o o e 45 The pointing error as function of height of target and distance between sensor and instrument with the height of target 200 km estimated with 50 km uncertainty Height set in SvalPoint ZOO Kin a ns Se ke eh eh ak A A re hia tl aa 46 The pointing error as function of height of target and distance between sensor and instrument with the height of target 200 km estimated with 50 km uncertainty Height set in SvalPoint LPR A A ethos ere eS EES A a te ah hy mate eh 46 Validation ofthe syst in ap o a oh ee Be A eae SE ee es Ge we oe Be 49 Basic design of the Observatory e 52 Instrument map of KHO ay Lot a a e eee Ea ah o e bs ek 53 Photos or KHAO 2 os 28 RR we Geek ah ee RR Fee GEA EB By Ry RR Be RAR 54 Illustration of the principal axes oaoa 55 Tlustration ofthe YTM wrah week Be REE EAE EE ee ea A eee 57 UTM grid zones in Scandinavia 2 ee 58 The user interface of the server applications 0 e 60 List of Tables 6 1 DGPS measurements and their equivalent in geodetic coordinates 6 2 Geodetic coordinates of instruments measured with hand held GPS device List of abbreviations API DDE DGPS EISCAT ETRS89 FOV GPS IDE IP IWRF KHO LTU PSRF RAD SWREF TCP UDP UNIS UTM VCL WGS Application Programming Interface Dynamic Data Exchange Differential GPS European Incoherent Scatter Scientific A
56. e the units controlled through pointing and they collect the scientific data Though instruments is a generic term in the case of SvalPoint it refers strictly to the instruments that are the subject to pointing The data acquired by the instruments do not affect the system The sensors are instruments that collect information about the target providing a mean to its identification The sensors are active part of the SvalPoint system affecting the result of the pointing In the following the basic parameters of the instruments and sensors available at KHO at the moment and possible to be used with the current version of SvalPoint system are presented 3 1 Instruments 3 1 1 Narrow Field of view sCMOS camera The Narrow Field of view sCMOS camera is designed to study small scale auroral structures The instru ment is composed of two parts an all sky scanner and a camera see Figure 3 1 The All Sky scanner is a Keo SkyScan Mark II a dual first surface mirror assembly with a 360 azimuth and a 90 elevation scanning put into motion by servo motors The accuracy of the pointing is 0 05 with 9 s azimuth and 27 s elevation speed The camera used is an Andor Neo sCMOS on a 40 C vacuum cooled platform mounted with a Carl Zeiss Planar 85 mm ZF lens with a relative aperture of f 1 4 See KHO 20140 Figure 3 1 The Narrow Field of view sCMOS camera Panel A Keo SkyScan Mark II Panel B Andor Neo sCMOS camera Image from KHO
57. ed In case of negative n and positive e the equation for w is f wi arctan 2 7 5 9 i In case both nj and e are negative the value of w is calculated by wi arctan 3 7 5 10 29 5 2 Direction based pointing The direction based pointing is controlling the instrument based on target identified and located by a sensor The location of the sensor and instrument are generally different and therefore setting the azimuth and elevation angle from the sensor points the instrument at a different location This problem is shown in Figures 5 4 and 5 5 The figures are done on large scale to illustrate the effect of the displacement in both azimuth and elevation angles the system is not intended to be used with such large spatial displacements between instruments and sensor One can easily see that an algorithm is needed to determine the direction of pointing for the instrument based on the direction identified at the sensor This algorithm shall take into consideration the place of the instrument and the sensor Sensor gt Wsensor j Target Figure 5 4 Top view illustration of the system showing effect of spatial displacement between the in strument and sensor for different locations the azimuth angle w that points towards the same target is different Target EL Sensor Vinstrument Instrument Figure 5 5 Illustration of the system from the side showing effect of spatia
58. ed on n e and u components neuSWRF AzEIToNEU AzEIWRF Target infinitely far away IWRF SWRF neulWRF O neuSWRF 0 neuIWRF 1 neuSWRF 1 neulWRF 2 neuSWRF 2 Transform from IWRF to PSRF translate and rotate vector neulWRF 0 neulWRF 0 xoff neulWRF 1 neulIWRF 1 yoff neulWRF 2 neulWRF 2 zoff neuPSRF RotateToPSRF neulWRF Calculate azimuth and elevation from neu not real elevation zenith AzEIPSRF NEUToAzEI neuPSRF Calculate azimuth command AzEIPSRF az RadToDeg AzEIPSRF az Calculate degrees in direction if AzEIPSRF az gt 180 then begin AzEIPSRF az 360 AzZEIPSRF az end else AzEIPSRF az AzEIPSRF az Str AzEIPSRF az sAzimuthPSRF memol Lines add azimuth sAzimuthPSRF Calculate number of steps nAzimuthPSRF round AzEIPSRF az PR Calculate elevation command AzEIPSRF el RadToDeg AzEIPSRF el Calculate degrees in direction if AzEIPSRF el gt 0 then begin AzEIPSRF el 90 AzEIPSRF el end else begin AzEIPSRF el 90 AzEIPSRF el end 69 Str AzEIPSRF el sElevationPSRF memol Lines add Elevation sElevationPSRF Calculate number of steps nElevationPSRF round AzEIPSRF el TR Set az and el on instrument if Comportl Connected then if nAzimuthPSRF lt PX and nAzimuthPSRF gt PN and nElevationPSRF
59. en consisting of two functions The first function gives the error in azimuth and elevation angles It takes as inputs the vector direction between sensor and instrument the vector direction between target and sensor and the height of the target above the reference ellipsoid an array of different heights It has fixed the height set in the SvalPoint for the target and the height of the sensor above the reference ellipsoid The function calculates the magni tude for the sensor target vector for each height input followed by the calculation of azimuth and elevation angles for the instrument target vector for each height Then subtracting from these values the azimuth and elevation calculated for the height of target set in the SvalPoint the error in pointing is achieved The second function generates different possibilities and plots the graphs The plots shall show the function between the angle error separately for azimuth and elevation the distance between the sensor and instru ment and the height of target above reference ellipsoid The hard coded parameters in this function are the limits for the height of target the limits for the distance between sensor and instrument the direction vectors both for the sensor instrument and sensor target In the case of the latter one all possibilities are investigated by generating all unit vectors on quarter of a sphere with the origin in 0 0 0 For this the following equations are used cos 0 sin p
60. ence University of Lulea Kiruna Sweden Bernhardsen T 1992 Geographic Information Systems Viak IT Norwegian Mapping Authority Brekke A 2012 Physics of the upper polar atmosphere Springer Dandekar B 1974 Simplified formula for the determination of the altitude of an auroral arc from a single station Journal of Atmospheric and Terrestrial Physics 36 5 829 834 Directed Perception 2007 Ptu d46 family Miniature pan tilt units Frey H Frey S Lanchester B amp Kosch M 1998 Optical tomography of the aurora and EISCAT in Annales Geophysicae Vol 16 Springer pp 1332 1342 Fujinon Fujifilm 2009 Cctv lens catalogue Geographic information Spatial referencing by coordinates 2003 Technical Report ISO 19111 2003 E Swedish Standard Institute Hager J W Fry L L Jacks S S amp Hill D R 1992 Datums ellipsoids grids and grid reference systems Technical report DTIC Document Hofmann Wellenhof B Lichtenegger H amp Collins J 2001 GPS Theory and Practice Fifth revised edition SpringerWienNew York Hower C Z amp Indy Pit Crew 2006 Internet direct indy an open source suite of internet components Version 10 1 5 Kaila K 1987 An iterative method for calculating the altitudes and positions of auroras along the arc Planetary and space science 35 2 245 258 Kannala J amp Brandt S 2004 A generic camera
61. equation the pictures taken with 10 steps has been analysed On the pictures the light source represents approximately 3 pixels in width and 3 pixels in height Therefore the central pixel has been used to determine the place of the light source in a 2 axis Cartesian coordinate system x and y on the picture Knowing the centre of the picture the distance of the light source from it in pixels can be determined The pixel size of the DDC1240C HQ camera used in the mount is 5 3m x 5 3um see Thorlabs 2011 and knowing that the full resolution of the camera is 1280 x 1024 while the recorded image is in 640 x 512 resolution the distance from the centre can be determined Assuming that the projection is equidistant and only a scaling factor is unknown then the following equation can be written r fe 8 fe a if where r is the distance of point from the centre of image fe is the effective focal length f is the focal length 0 is the angle between optical axis and the incoming ray in radians and a is the scaling factor 6 6 Using the angles measured then adjusted and the distance of the source determined from the images an f for each angle can be calculated Calculating the mean value for the effective focal length gives fe 1 42463427mm resulting in a 1 017595907 The largest difference between two fe values is 0 0157 mm therefore it can be concluded that the projection is indeed equidistant Note these values apply for the spe
62. gps gov systems gps performance accuracy l Accessed 2014 09 07 Norwegian Polar Institute 2014 Toposvalbard http toposvalbard npolar no Rees M 1963 A method for determining the height and geographical position of an auroral arc from one observing station Journal of Geophysical Research 68 1 175 183 Sharp W Rees M amp Stewart A 1979 Coordinated rocket and satellite measurements of an auroral event 2 the rocket observations and analysis Journal of Geophysical Research Space Physics 1978 2012 84 A5 1977 1985 Sigernes F 2000 Direct georeferencing Fragment of lecture notes from UNIS course AGF 331 Spec troscopy and remote sensing Sigernes F Dyrland M Brekke P Chernouss S Lorentzen D A Oksavik K amp Deehr C S 2011 Two methods to forecast auroral displays Journal of Space Weather and Space Climate 1 1 A03 Sigernes F Lorentzen D A Heia K amp Svenge T 2000 Multipurpose spectral imager Appl Opt 39 18 3143 3153 Sigernes F Moen J Lorentzen D Deehr C Smith R Vieroset M Lybekk B amp Holtet J 1996 Scifer height measurements of the midmorning aurora Geophysical research letters 23 14 1889 1892 Str mer C 1955 The Polar Aurora Oxford University Press Swan T 1998 Delphi 4 Bible IDG Books Worldwide Inc Terry Jr N 1996 How to read the universal transverse mercator
63. he instrument in the case of one controlled instrument or in the centre of the formation in case of multiple instruments For targets such as the aurora the height determination is more complicated see Appendix C nevertheless possible However as it is very probable to do only a rough estimation of it for simplifying the software usage Section 7 1 is dedicated to calculate the effect of a wrong estimation on the pointing accuracy Once the height of the target has been identified the magnitude of the vector pointing from the sensor to the target shall be calculated The problem is illustrated in Figure 5 7 Figure 5 7 Calculating the magnitude of vector based on the height of the target The lengths are not to scale for the purpose of better illustration of the problem In Figure 5 7 ST is the length sought TF is the height of the target and the angle marked with y is the elevation angle identified by the sensor Since the geodetic location of the target is not possible to identify the radius of curvature in prime vertical cannot be calculated Therefore to minimise the error induced the following calculation has been made considering that the aurora visible at KHO is the one appearing between the latitudes of 65 961 and 82 136 values from the program SvalTrack IT the radius of curvature in prime vertical for those values is calculated and their mean value 6385992 9039 m is used for the lengths of OS and OF This results in assumi
64. igned to obey one of the following relations for projections r 2 f tan 0 2 stereographic projection 2 4 r f 6 equidistance projection r 2 f sin 0 2 equisolid angle projection r f sin 0 orthogonal projection All four expressions are implemented in the Sval X Camera application subject to user settings In the following the relations are to be developed with the use of the most common type of fish eye lens with equidistant projection Based on Equation 2 4 and Figure 2 2 It shall be noted that due to the fact that the lens is circular W1 Wa 2 6 From Equations 2 5 and 2 6 the value of 0 and w can be calculated directly These values represent the azimuth and elevation of the point in X Y Z based on the image captured by the all sky camera 13 image plane Y Figure 2 2 All sky lens model Figure adapted from Kannala amp Brandt 2004 The robustness of the software is guaranteed by input for the attitude of the instrument This is used on one hand to be able to place the projection of the point in a local level world reference frame not related to the orientation of the camera and on the other hand to calculate and draw the line of horizon on the picture captured by the instrument The application of the rotational matrix and hence the disconnection of the coordinates from the camera s orientation is done with the use of rotation matrices see the previo
65. instrument is controlled by the motors translated by a vector T and rotated by the Tait Bryan angles see Appendix B compared to the IWRF The XOZ plane in this reference frame is the plane in which the elevation control motor motion takes place The YOX Plane is defined by the motion plane of the azimuth control motor The X axis of the frame is defined by the intersection of the two planes pointing in the direction of the instrument s optical axis when the control motors are in their home position The Z axis points upwards in the plane of the elevation control motor perpendicular to X Y axis complements the coordinate system to a left handed reference frame The control of the instrument is done in the PSRF therefore all pointing algorithms calculate the target s direction in this coordinate system In Chapter 4 the principles of the two different target based pointing modes have been presented The geo pointing mode takes as input the geodetic latitude longitude and altitude of the target Knowing the geodetic coordinates of the instrument the vector between the two points is to be calculated The vector is calculated in IWRF then transferred to the PSRF In the direction based pointing mode the target is defined by its direction in the Sensor World Reference Frame The server application in addition to the direction receives the geodetic information about the location of the sensor making it possible to calculate the direction of poin
66. l displacement between the instrument and sensor for different locations the elevation angle y that points towards the same target is different 30 Then the steps for the direction based pointing control are the following 1 Calculate vector between instrument and target in IWRF based on the vector from the sensor 2 Represent the same vector in PSRF 3 Transform the representation of the vector from Cartesian coordinates to spherical coordinates Steps 2 and 3 have already been covered in the previous section describing geo pointing see Sections 5 1 2 and 5 1 3 5 2 1 Calculating the vector from the instrument to the target To calculate the direction of pointing for the instrument we shall know the vector from the sensor to the target and the vector between the sensor and instrument Knowing them both represented in the same reference frame the vector between the instrument and the target can be determined by subtraction The vector between sensor and instrument is calculated in SWRF with the method used in geo pointing based on geodetic locations The vector from sensor to target is determined based on data acquired by the sensor in SWRF However in some cases this data contains the azimuth and elevation of the target but not its range Therefore sometimes only the direction of the vector is known not its magnitude To calculate the direction of the vector let s consider a unit vector v as shown in picture Figure 5 6 defined
67. lculate azimuth and elevation angles nAzimuthPSRF Integer nElevationPSRF Integer variables read from command lat real lon real alt real az real 66 el real h real Angles based control variables vl real geodetic coordinates based control variables HomeC Geodetic Target Geodetic PointingDir Vector Variables for the SWRF IWRF PSRF transformation neulWRF Vector neuSWRF Vector neuPSRF Vector neuSI Vector Sensor Geodetic begin AContext Connection Socket WriteLn DateTimeToStr Now PTU_D46 Connection set up repeat While end command is read Read New Command sInCommand AContext Connection Socket ReadLn Saving command in log file if continuous logging is on if ContLog State cbChecked then begin Append Log Write Log DateTimeToStr Now sInCommand String 13 10 CloseFile Log E end Memol Lines Add sInCommand Open COM port if not ComPortl Connected then try ComPortl Open except on E Exception do begin memol lines add Comport not connected end end Home command if sInCommand Home or sInCommand home or sInCommand HOME then begin home false New home command recieved GoHome if Comport1 Connected then begin while home false do 67 begin timerl enabled true sleep 10 sendemd TP sendcmd PP e
68. lient application Indy makes the program development very fast however it does have one downside it uses blocking socket calls Blocking socket calls mean that when a reading or writing function is called it does not return until the operation is complete Due to this it is very easy to program with these functions however they block the thread of the application causing the program to freeze it does not respond to any command and it need to be closed from the Task Manager This would be a major problem if a continuous data stream was sent over the TCP sockets However as explained earlier in this chapter this problem has been out ruled by design Another implication of the blocking sockets is that during implementation special attention shall be paid so that each message sent over the socket is read on the other side of the communication Hower C Z amp Indy Pit Crew 2006 4 2 2 Dynamic Data Exchange The Dynamic Data Exchange DDE is a protocol in Microsoft Windows for fast data transfer between applications that was introduced to exchange the clipboard operations in 1987 Each side of the commu nication both the server and the client of the DDE data transfer may start a conversation by transferring data or requesting data from the other The role of the server and client can be switched during one session and there may be multiple clients in the conversation Swan 1998 In the case of the control interface and client SvalCast co
69. loped in the duration of this thesis project e a client program that acts as a data transmitter between the control interface and the server applications its responsibility being to transfer the commands and all necessary information to the server and to display the messages sent as feedback from the server this program is also developed during the work associated to this thesis At the definition of the system there has been two options to consider either to integrate the client ap plication into the control interface programs or to develop a separate software for it The decision fell on the latter one for the following reason the user interface programs implement many functionalities already and there was no room planned for such an extension from the beginning of their development The control interface programs are preferred to provide a continuous data stream without waiting for re sponse sending positions at regular time intervals The reason for this is that in case there is hold up for feedback the control interfaces would not be able to update their real time features such as the basic video acquisition or the tracking of an object Displaying feedback from the instruments in the client is considered not a vital however a highly desired feature Since the locations of the control personnel and the instrument can be kilometres apart it is helpful to know whether the command has been executed or not One might argue that it is visible f
70. m a picture such as mountain tops and features of the sea shore The determination of their geodetic coordinates and height has been done based on the maps provided by the Norwegian Polar Institute Nor wegian Polar Institute 2014 Test 2 The pointing methods based on the all sky camera have been tested after calibration The testing equipment is the following the Tracker Camera instrument 1 placed at approximately 30 cm distance from the alls sky camera sensor both of them being located in the same dome and the Narrow Field of view sCMOS camera instrument 2 located at 5 m distance from the sensor two rooms away The chosen target is a mountain showing on the horizon for which due to its proximity the system is expected to perform worse than for the primary target It shall be noted that the tests have been conducted with a fixed 110 km height of target This induces for the Narrow Field of view sCMOS camera a maximum error of 0 2629 in azimuth and 0 007 in elevation however in the specific scenario it is much smaller 0 in azimuth and 0 0104 in elevation according to mathematical calculations similar to the ones presented in Section 7 1 The Tracker Camera being at approximately 30 cm distance from the sensor is not affected by this error the first noticeable difference 0 05 the pointing accuracy of the instruments appears at 75 cm distance from the sensor in case of a 1 km target altitude the approximate height of the surr
71. more details on the equidistant projection equation The calibration is done with a small light source mounted on an arm of 1 m that is in turn mounted on a tripod with a panning module showing the degrees of rotation The alls sky camera is fixed to a platform and the following coordinate system is considered the x axis coincides with the optical axis and y is perpendicular to it in the centre of the lens Plane xy is parallel with the plane of the arm s movement The tripod is placed under the lens aligning the centre of the rotation of the arm with the centre of the lens as precisely as possible The spatial offset is measured with the help of a pendulum and measuring tape giving an offset on the x axis of 0 75 cm and 0 cm on the y axis The levelling of the tripod and camera platform has also been adjusted to the best possible and measured with a high resolution 0 01 level The measured offsets of the tripod are 0 57 around the y axis and 0 04 around the x axis while the same measures for the platform are 0 06 around y axis and 0 2 around x axis The height of the tripod is adjusted to have the light source shining exactly at the middle of the lens adjustment made using the pictures captured by the camera To calculate the FOV the arm is rotated around to the point when the light source disappears on the horizons On both sides the angle value on the panning module is read From these values not only the FOV but also the angle val
72. nation of height If everything is shown to be correct and the instruments still do not point at the same target the system might have reached its accuracy limit See more about it in the section Accuracy of pointing E 4 5 Target acquisition stops unexpectedly In case during the operation of the system it stops first restart both SvalCast and the control interface used Then if the problem still persists verify that the servers are still connected to the internet alternatively restart them 62 Appendix F Code fragments from server programs This appendix shows fragments from the code of the server applications Listing F 1 shows the type definitions used throughout the server programs for better readability Please refer to this listing for the understanding of variables in the other code fragments Listing F 1 Type definitions used in the server programs type all angles in radians Cartesian Record X Y Z Real End Geodetic Record lat lon alt Real End LocalLevel Record az el Real End RotMatrix array 0 2 0 2 of Real Vector array 0 2 of real Listing F 2 is an example for the implementation of basic functions not related directly to the application however necessary due to their lack in the language Pascal by Borland Listing F 2 Example for a basic function Arccos function function TPTU46TrackerF arccos a real real begin arccos ArcTan sq
73. nd timerl enabled false end else errorinCmd True COM port not connected if home true then AContext Connection Socket WriteLn DateTimeToStr Now PTU_D46 Command executed else if errorinCmd True then AContext Connection Socket WriteLn DateTimeToStr Now PTU_D46 _Error in command end Azimuth and Elevation command Receives lat lon alt az el if sIinCommand AzEl or sInCommand AZEL or sInCommand azel or sInCommand Azel then begin errorinCmd False New commands Read commands in order sInCommand AContext Connection Socket ReadLn lat getlat sImCommand sInCommand AContext Connection Socket ReadLn lon getlon sInCommand sInCommand AContext Connection Socket ReadLn alt getalt sIinCommand sInCommand AContext Connection Socket ReadLn az getaz sInCommand sInCommand AContext Connection Socket ReadLn el getel sInCommand If all inputs are correct if errorinCmd False then begin Set the new azimuth and elevation value in the AzEIWRF AzEIWRF az DegToRad az AzEIWRF el DegToRad el Set sensor coordinates Sensor lat DegtoRad lat 68 Sensor lon DegtoRad lon Sensor alt alt Set instrument coordinates HomeC lat DegtoRad lath HomeC lon DegToRad lonh HomeC alt alth Calculate vector bas
74. nded not by angle values but step numbers The transformation is done by the help of the PR real and TR real variables set from the setting tab to the motor resolution Also the boundaries of the unit are checked before sending the command to the unit by comparing the values to the minimum and maximum positions of both motors saved in the PN Integer PX Integer TN Integer and TX Integer variables When the command is being sent to the instrument the procedure SendCmd S String is called This sends the string on the COM port The string contains the word marking which motor shall move PP for the pan motor controlling elevation and TP for the tilt motor controlling azimuth followed by the number of steps that shall be executed The while loop after the sending of the command shall be noted The donea donee boolean global variables mark whether the command has been executed or not The flags are set on true when the feedback from the unit marking its position contains the expected values While the command has not been executed the current position of the unit is requested Last upon the execution of the command feedback is sent to the client Listing F 5 Fragments of the function called when a string is received in the TCP Socket COMMAND FROM CLIENT procedure TPTU46TrackerF IdTCPServerlExecute AContext TIdContext var String to read command from client sInCommand String Integers to ca
75. ndicated in the client and finally attempt connection to several servers some of them connected to the internet others not making sure that the ones connected react to the commands while for the disconnected ones the lack of connection is indicated Each control possibility with all interfaces shall be validated During the tests all instruments shall be pointed and the data collected shall be analysed to confirm that the target was indeed acquired 1 pointing at geographical features identified in a map using geo pointing making sure that each target is found in the centre of the pictures pointing at targets identified in the sensor covering both targets close to the horizon and at zenith position making sure that all instruments acquire the same target pointing at auroral structures making sure that the acquired target is consistent for all instruments but also assessing the speed of the operation of SvalPoint versus the dynamics of the aurora tracking the moon with all instruments making sure that the target stays in the field of view of the instruments after an extended time tracking of stars with instruments verifying that the targets are not lost after extended time tracking of satellites shall be done on a selection that are visible in the night sky and it shall be verified that the instruments keep the satellite in their field of view during its visibility above the horizon 47 8 2 Performed validation S
76. net The system has been defined during the time of the thesis work incorporating new and previously developed applications into a software package The different programs interact to define a target and point a number of instruments at it In the presentation of SvalPoint the key elements are the design of the software system the algorithms used for the control and in order to ensure the correct operations the hardware calibration To create a complete image of the system in addition both the hardware and the projects incorporated are presented As to finalise the software development its testing is described along with the assessment of the system s accuracy Aspects regarding the work process are also presented definition of goals task analysis conclu sions and suggestions for further work Acknowledgement Foremost I would like to thank Prof Dr Fred Sigernes for providing me the opportunity to work on this exciting project at The Kjell Henriksen Observatory under his supervision I would also like to thank him for all the times he has driven me up to the observatory in the belt wagon and for all the support he has provided during my work I could not have envisioned a better supervisor I also appreciate the help of my teachers from Kiruna I wish to express my deepest gratitudes to Dr Anita Enmark for being the role model always believing in me helping me to find my interests and offering advice and guidance on career choices I am al
77. ng a sphere instead of an ellipsoid that further simplifies the calculations by the relation a y 90 The final equation for the vector magnitude therefore is ST OS cos a YOT OS sin a 5 13 32 Chapter 6 Calibration For the correct functioning of the system each unit playing active role in SvalPoint shall be calibrated The following information shall be acquired about each of them e geodetic location latitude longitude and altitude e home attitude in Tait Bryan angles roll pitch and yaw In addition to these values it must be ensured that the sensors provide correct data hence all their parts contributing to target location is calibrated The scientific data from the instruments does not play active part in the pointing system therefore their calibration is not a part of the SvalPoint calibration process 6 1 Geodetic positioning of the instruments and sensors The positioning of the instruments is done by Differential GPS DGPS measurements for the centre of the instrument domes Since all positions in the software are required in geodetic coordinates and the DGPS measurements are performed in UTM system transformation from it into geodetic coordinates is required See more information about the UTM in Appendix D 6 1 1 Differential GPS Differential GPS or DGPS is an enhancement to the Global Positioning System that increases the location accuracy up to 10 cm in contrast to the approximately 8 m
78. ngle displacement for the lens 3 the two angles having the relationship a gt 6 B AE C Figure 6 7 Top view of the calibration set up Illustration of the effect of a spatial offset of the rotational axis of the arm and the centre of the camera OB on axis x of the lens calibration system To calculate we consider the triangle ABOC as in Figure 6 8 In this triangle the lengths CB and OB are known CB is the length of the arm and OB is the displacement on axis x in the system Also note that from Figure 6 7 angle a is the measured angle on the panning unit of the tripod y C D Figure 6 8 Calculating the angle for the fish eye lens based on the angle measured in the calibration system ABOC The relations in ABOC are a 180 a sin a ae OB heat cos a OB 3 OF 6 1 sin y 5E ia CD sy cost 56 CD DB CB a B 7 180 40 From Equation 6 1 follows OD OB sin a 6 2 DB OB cos a Pa and CD CB DB OD CD 6 3 OC 902 T Based on the trigonometric equation sin y cos y 1 OC VOD 0D 6 4 Therefore uen y arcsin Be gt 6 5 B 180 y o 6 3 2 The measurements The measurements considering the angle adjustments show that the horizon is on 97 from the centre resulting in a FOV of 194 the same as the value found in Krishnan amp Nayar 2008 To calculate the projection
79. nnection the communication is one way Sval Cast acts as the client in the DDE while the control interface is the server Once the communication is established there is a continuous data stream between the two applications 4 2 3 SvalPoint high layer protocols The SvalPoint system has two different high layer communication protocols defined information format for data communication between control interface and client and command formats for server control Control interface client protocol The control interface and client protocol communication must contain the following information the geode tic location of the observation latitude and longitude in degrees altitude in metres the direction of target azimuth and elevation in degrees and the altitude of the target in kilometres A target altitude equal to zero indicates the lack of information on the altitude in which case the target is considered infinitely far away Note As the geo pointing is not possible at the moment through the control interfaces no protocol has been defined for it yet The control interface sends one string of characters to the client containing information in the following format A latitude B longitude C altitude D azimuth E elevation Z altitude of target S 22 Client server protocol The client server communication is bidirectional The client sends commands to the server to control
80. oard is however already in use by the con trol interface applications for communication with different small programs and as the protocol provides no mean of targeting the data written to it this option is discarded leaving the Dynamic Data Exchange as the mean of communication See Section 4 2 2 for more information on the Dynamic Data Exchange protocol The client server model followed is presented in Figure 4 2 There are several control interfaces that can command the client to which multiple servers are connected through the internet It shall be noted that despite the possibility to start multiple control interfaces at the same time it is counter advised It is not restricted due to possible advantages of this feature however unintentional use shall be avoided by always closing one control interface before opening another Control Interface 1 Control Interface 2 s Control Interface n DE cn DDE DDE Client rcp socket Internet TCP socket TOP socket TCP socket y ani A Server for Instrument 1 Server for Instrument 2 ae Server for Instrument n Figure 4 2 The general network model followed One of the challenges in the development of the system is to make the programs freeze proof At the usage of any system one of the most irritating things is when one of the programs stops responding to commands and must be closed from the Comman
81. oday resulting in numerous scientific articles The earliest studies use triangulation in general based on different cameras narrow field of view all sky with a spatial displacement from 4 to 100 km An early study of auroral heights is done in Strgmer 1955 using narrow field of view camera photography placed at distances of only a couple of kilometres calculating the altitude of a single point in the auroral arc Studies on the determination of the height and position of the aurora based on a single sensor has been conducted in Rees 1963 followed by Dandekar 1974 further improving the method Kaila 1987 shows a method for determining the height along the entire auroral form with a 1 km precision if certain criterion are met using two all sky cameras placed at 100 200 km apart from each other More recent articles on the subject are Sigernes et al 1996 determining the height of midmorning aurora with photometers and Whiter et al 2013 presenting a method for finding the peak emission height of the aurora based on a pair of all sky camera images bringing improvement in speed accuracy and level of automation compared to the earlier works The presented methods for locating the place of aurora involve visual or photometric data However due to the nature of the phenomenon other measurements can be used as well by understanding the basic process of the aurora The cause of the aurora is protons and electrons accelerated at thousands
82. of kilometres height The large flux of electrons moving downwards into the ionosphere called electron precipitation collide with atoms and molecules getting them in an excited state The excess energy during the de excitation creates optical emission auroral arcs and increases conductivity by creating secondary charged particles The optical emission and conductivity profiles are strongly dependent on the flux and energy spectrum of the pre cipitating electrons Therefore models can be used to determine the height of the aurora among other parameters in case information about the precipitating electrons is available To determine these parameters different approaches may be used One approach is to collect in situ data from satellites or sounding rocket measurements An example for the latter one presented in Sharp et al 1979 showing height distribution of emission rates ion densities auroral electron densities and flux One of the EISCAT radars located in close vicinity of KHO can also be used to determine the height EISCAT determines the height distribution of the electron density and electron temperature among its four basic parameters These parameters can be also combined with optical observations making complex observations possible In Frey et al 1998 a three dimensional model of the auroral emission is constructed with the use of optical tomography and EISCAT data In conclusion after presenting different methods and options for
83. om KHO 20144 53 Figure A 3 Photos taken at KHO showing the domes on the roof housing the instruments the building with the road leading to it and the corridor of the instrumental wing with the instrument modules on both sides 54 Appendix B Tait Bryan angles The Tait Bryan angles also named as asymmetrical Euler angle sets or 3 2 1 Euler angles represent rotations around three distinct axes x y and z The angles are named roll pitch and yaw and in the case of a ship or aircraft they are defined as follows Berlin 2007 e roll is the rocking movement around the longitudinal axis in general rotation around axis x e pitch is the up down movement of the longitudinal axis in general rotation around axis y e and yaw is the sideways movement of the longitudinal axis in general rotation around axis z In the case of an aircraft Figure B la illustrates the three angles The same angles are adapted for the different reference frames associated with optical instruments the rotations around the axes follow the convention described For a left handed reference frame placed in the centre of the lens see Figure B 1b a The principal axes of an aircraft Mahoney 2014 b The principal axes of a camera Figure B 1 Illustration of the principal axes 55 Appendix C Calculation of the height of aurora The determination of the height of aurora is an issue that has been studied since the 1950 s yet still a problem t
84. ounding mountains calculated with MATLAB similarly to the calculations in Section 7 1 The pictures recorded during this test are shown in Figure 8 1 The total error in pointing is the angle between the optical axis and vector to the target from the centre of the instrument lens For the Tracker Camera this is 0 7725 whilst for the Narrow Field of view sCMOS camera it is 0 0259 As one might notice in Figure 8 1 the target on the all sky camera is at a very low elevation angle appear ing as just a few pixels on the image with barely identifiable features Indeed after selecting the target on the picture usually naked eye test has also been preformed to see better how does the feature look like and hence be able to identify it on the images acquired by the instruments The erroneous identification of targets shall induce the same magnitude error in all instruments an offset from the intended target of pointing Considering the fact that the two instruments have different error in pointing an error not justified by wrong target selection and larger in case of the Tracker Camera further error sources shall be considered The most probable cause is identified to be calibration error in the initial attitude measurements As described in Chapter 6 the calibration method has been different and more inaccurate for the Tracker Camera that took the second image in Figure 8 1 As mentioned in the same chapter at the time of the calibration there h
85. programs please consult the dedicated documentation or contact the person in charge Alternatively Telnet can be launched and the commands can be sent in raw format See section Format of commands for more details 60 E 3 Format of commands There are five different commands that can be sent to the servers Two of them are routine commands the homing command home command word and the end of connection command end keyword The fist target acquisition command is for geo pointing with the keyword gps The second and third one are for direction based pointing when the height of the target is known command word azelh and when the target is considered to be infinitely far away compared to the distance between sensor and instrument command word azel The format of the commands is as follows each line is sent as a separate message e Send instrument into home position keyword HOME Home or home e Geo pointing keyword GPS Gps or gps the value of latitude in degrees defining the target the value of longitude in degrees defining the target the value of altitude in metres defining the target e Direction based pointing azel keyword AZEL AzEI Azel or azel the value of latitude in degrees defining the place of sensor the value of longitude in degrees defining the place of sensor the value of altitude in metres defining the place of sensor
86. rget in degrees in the order described Example AZEL 78 147686 16 039011 523 161 12 6 25 1 e AZELH alternatively azelh Azelh or AzEIH The keyword AZELH must be followed by six values It is the same five values as for the AZEL adding the height of the target above ground in km as the sixth parameter Example AZELH 78 147686 16 039011 523 161 12 6 25 1 200 e END alternatively end or End Ends the connection between the client and server application There are no values following this command Any feedback from the servers is a single string that forms a message sentence directly displayed in the client application without any interpretation 4 2 4 Erroneous commands and feedback to client To avoid cases in which the client sends commands too fast the server application always waits for the execution of the motion by the instruments An inquiry to the motion control unit is sent regarding the current position and the program is blocked in a while loop until the expected response indicating that the instrument is in the desired position is sent on the COM port As soon as the response is satisfactory a feedback string is sent to the client containing the Command executed sentence This mechanism relies on the assumption that all commands sent to the instruments are correct and pos sible to be executed According to this method once the command is sent on the COM port the program is blocked until the motion is executed
87. rom the images captured by the instruments However there might be exceptions to this assumption such as in case the images are not streamed over the internet but saved on the local drive Moreover the isolation 19 of problems in control and data acquisition would not be possible As what regards the continuous command stream that is not desired on the server side since reading interpreting executing and confirming the execution of commands takes time this being true even in case the command was the same as the one before This lead to the very logical design decision the same commands shall be filtered out from the stream leaving only the ones that change the pointing of the instrument As the servers are aimed to be kept general simple and easy to use it is the client program that is desired to act as the filter of the data stream The functionalities of the servers are therefore defined to include the reading of the commands the in terpretation and calculation of the direction of pointing and the sending of feedback to the client upon execution See Appendix F for code fragments from the server programs The client application named SvalCast is defined to be responsible for the reading of the data from the control interface programs the filtering of the stream and the sending of the commands to the servers The control interface from the system s point of view is responsible for providing a stream of pointing directions for the inst
88. rt l sqr a a end 63 Listing F 3 shows an example for error detection in the information coming from the client The procedure that executes when a string arrived in the TCP socket calls this function to extract the information from the string received First it is checked that the received string indeed contains a number followed by checking that the number is within the requested boundaries 90 90 in this case If it is not in the boundary a global boolean variable errorinCmd boolean is set that indicates that there has been an error in the command Listing F 3 Example for error detection The algorithm that reads the latitude value from the client Get latitude input function function TPTU_D46_Serv getlat sInCommand String Real var Variables for interpreting commands Code Integer string to int conversion help variable Value Real string to int conversion help variable lat real begin lat 0 Saving command in log file if continuous logging is on if ContLog State cbChecked then begin Append Log Write Log DateTimeToStr Now sInCommand String 13 10 CloseFile Log end Check if the command is a number If it is save it in lat Val sInCommand Value Code if Code 0 then begin lat Value if angle is not out of range if lat lt 90 and lat gt 90 then begin errorinCmd True end end else errorinCmd Tr
89. ruments See Figure 4 1 for an overview of the data exchange between the elements of the system Control interface Information stream about the target from control interface Y Client A Filtered command See Feedback about execution stream from client of commands from server yd Y Su Server 1 Server 2 we Server n Figure 4 1 Overview of the data exchange between the system parts The pointing methods for the instruments defined that all servers must be able to execute fall into two main categories The first category is the target independent commands with only one command falling in it the HOME command This command sends the instrument to its home position defined by the control unit The second category is pointing at target which can be defined either by geodetic location the method being called geo pointing or by azimuth and elevation of target acquired from a sensor accompanied by information about the sensor location and height of target indicating the length of the vector between the sensor and target The latter referenced to as direction based pointing henceforth may have two options when the range of the target is unknown and the target is considered to be infinitely far away and when the range can be estimated by estimating its height of target above the reference ellipsoid The algorithms used for the different methods are described in the Chapter 5 It sh
90. s based on PTU D46 unit no accuracy is available however the resolution of motion is known to be 0 0129 Based also on the availability of the digital levels one with 0 01 resolution is chosen Furthermore the equipment is factory calibrated ensuring the most precise measurements possible In case the level is placed on the instrument platform it is assumed that the platform and the instrument are perfectly aligned inducing possible errors in the calibration However as the instrument rests on the platform in the case of the Narrow Field of view sCMOS camera and the Fs Ikea this error is minimum Special attention shall be paid to the alignment of the level with the instrument The level however has 37 very convenient flat surfaces on all sides therefore it can be easily aligned with the edges of the platform In both cases both the yaw and pitch error turned out to be 0 02 indicating that perhaps these angles are induced by the building itself In the case of the Tracker Camera and the all sky camera however the assumption of their alignment with the platform induces errors in the scale of entire degrees This is due to the fact that the platform is constructed of raw worked wood and metallic brackets fixed with screws Moreover there is no space for placing the level accurately Therefore a different approach is taken for the measurements that is similar to the yaw calibration For the Tracker camera after making an initial measurement of
91. s of 9 12 12 and 9 respectively reducing the number of zones from seven to four resulting in the fact that the grid zones 32X 34X and 36X are not in use Figure D 2 UTM grid zones in Scandinavia Figure from Bernhardsen 1992 58 Appendix E Fragments from the user manual to the SvalPoint system Due to the complexity of the system a user manual is provided to it that contains practical information for the operator of the system It also describes the structure of the software and the algorithms used for the developer maintaining and extending it This appendix shows fragments of the user manual showing examples of the practical information included in it E 1 What is SvalPoint The SvalPoint system is a collection of software programs that control a number of optical instruments at the Kjell Henriksen Observatory KHO The instruments are controlled with internet protocol therefore they can be controlled from the building of the University Centre in Svalbard UNIS It shall be noted however that the Firewall settings in Windows on the computers at KHO do not allow access from other than PC s registered as part of the KHO network E 2 How to use SvalPoint On the computers connected directly to the instruments at KHO the server programs shall run Fs Ikea Tracker for the Fs Ikea instrument KeoSkyScanner for the Narrow Field of view sCMOS camera and PTU46 Tracker for any instrument fixed on PTU D46 platform
92. sCMOS camera yaw calibration error height of target error target identification error e Tracker Camera roll pitch and yaw calibration error target identification error 49 Chapter 9 Conclusions The system developed during this thesis enables a large range of scientific observations Some of the obser vations that can be done for the first time at KHO are multiple instruments pointing at the same target acquiring different data in their nature complementing each other the same target can be observed by a satellite performing in situ measurements and ground station with the satellite tracking feature Also for the first time at the observatory target acquisition became very intuitive and easily done However most importantly this system has accomplished the control of the instruments over the internet opening up a wide range of possibilities for future development representing their corner stone The current version of SvalPoint consists of 6 software applications categorized as follows by their role in the system server client and control interface Each instrument is associated with a server application running on its control computer controlling the instruments commanded through the client with data about the target from one of the control interfaces The control interface applications had already been developed at the start of the thesis and only minor changes have been required in them The client
93. sed further on is defined and the different instruments operated by SvalPoint are shortly summarized In the first part of Chapter 4 the components of the system are described along with their interaction com munication protocols including high layer protocols defined during the project The last section presents what operational errors are detected in SvalPoint and the actions taken at their appearance Chapter 5 starts with the definition of naming conventions used for the description of the algorithms In the followings the algorithms on the server side are presented used for the pointing of the instruments Chapter 6 describes the necessary calibration processes for the system along with details regarding the calibration done during the practical work Chapter 7 is dedicated to the discussion of accuracy All factors contributing to it are described with numerical calculations where possible In Chapter 8 the tests necessary for the validation of the system are defined Further on the partial val idation of the system is presented together with expected results for the final trial as in contrast to the present results Finally Chapter 9 summarizes the conclusions of the thesis and presents some suggestions for future work to enhance the existing system 10 Chapter 2 Previous projects at UNIS This chapter presents projects related to the SvalPoint system that has been studied during the work process or used directly in the
94. so thankful to Dr Johnny Ejemalm for offering excellent advice in the choices regarding my thesis project I cannot possibly express my gratitude to all the extraordinary people I have met during my studies they had much influence on me and my view of life I would like however to thank the most my dear friend Patrik Karrang for his company on Svalbard for sharing the excitement in the discovery of the far Arctic for the fun times his moral support and last but not least for being there whenever I needed a second opinion another point of view or a second pair of hands during my work Lastly I would also like to thank my parents for their love and support during my years of education I am the most grateful to them Contents Introduction Til Project aims ti A or a ee eS A ee ee a a ee Ge 1 2 Task analysis sists ete aoc gh GG geste ae Ree eo Rh A kG tr ihe eae Gd ioe Outline oF Thesis isaac Pe awe Ee Ae bbe dled Gee Previous projects at UNIS 2 1 Airborne image mapper 2 0 i i a E A A S e A Aee i ha a EE a E 22 Vale CAMELA IA gale ee A A A ee ee ee ete E a A 223 Svallracio lc E A Bt eh he Se ee we ee ee a eee fa SvalPoint Hardware Bel Inistruments 3s 2 lt i pe kee de Sick oh A WW Goa e lar BALA Pale Ek Ok a er ee ea a Ga 3 1 1 Narrow Field of view sCMOS camera 20 2 00000 eee eee 3 1 2 Hyperspectral tracker Fs Ikea o ee 3 1 3 Instrument constructed on the PTU D46 platform
95. ssociation European Terrestrial Reference System 1989 Field of View Global Positioning System Integrated Development Environment Internet Protocol Instrument World Reference Frame The Kjell Henriksen Observatory Lulea University of Technology Pointing System Reference Frame Rapid Application Development Sensor World Reference Frame Transmission Control Protocol User Datagram Protocol The University Centre in Svalbard Universal Transverse Mercator Visual Component Library World Geodetic System Chapter 1 Introduction The Kjell Henriksen Observatory KHO is an optical research station focusing on the middle and upper atmosphere It is located in Breinosa at 15 km distance from the centre of Longyearbyen on Svalbard Norway During the past two years there has been an acquisition of optical instruments that are capable of all sky tracking by the use of 2 axis motorized flat surface mirrors The observatory has however been yet lacking an efficient system for the control of these instruments The goal of this thesis is to define and develop a real time control system that is convenient to use for observations ultimately named SvalPoint 1 1 Project aims The optical instruments are placed in the instrumental modules of the observatory building Each module consists of a dome room housing the instrument and ensuring a 180 visibility to the sky through the roof of the observatory and a 1 25 m wide control room housing a computer
96. sulting angles out of range The control units have a maximum and minimum value for the angles that can be set in the server applications These values are different for the different instrument control units For example the PTU D46 unit cannot set greater elevation angles than 47 Therefore a command that results in such an elevation value in its server application returns the Error in command string to the client 4 3 The current version of SvalPoint The current version of the SvalPoint system is composed of the following programs e SvalTrack II as control interface e Sval X Camera as control interface e SvalCast as client e Fs Ikea Tracker as server for the Fs Ikea instrument e Keo Sky Scanner as server for the Narrow Field of view sCMOS Camera instrument e PTU46 Tracker as server for the Tracker Camera and the test system The client server model adapted to the current version of SvalPoint is shown in Figure 4 3 It shall be noted that any of the applications may be modified as long as the interface requirements are kept ensuring the robustness of the system SvalTrack II Sval X Camera DDE DDE SvalCast TOP socket TCP s TCP s TCP s Pen a Fs Ikea Tracker Keo Sky Scanner PTU46 Tracker Figure 4 3 The client server model of the SvalPoint System 24 Chapter 5 Pointing algorithms The pointing algorithms are all implemented on the servers si
97. system The SvalPoint system is preceded by two standalone software applications the Sval X Camera and SvalTrack II that are used as parts of SvalPoint with minimal modifications The airborne image mapper software on the other hand is presented and studied as a similar application in some aspects and solutions in it are adapted in the new programs of the SvalPoint 2 1 Airborne image mapper The airborne image mapper is a software that projects photos taken by a camera mounted on a helicopter to the Google Earth map as part of a large project at KHO presented in Sigernes et al 2000 By knowing the location of the helicopter in geodetic coordinates its attitude and the initial orientation of the camera in reference to the vehicle carrying it the location of the picture is identified In other words this program solves the transformation of points defined in a local reference frame in the image into points in world reference frame identifying their place on the map The same transformation is a key element of any pointing system for multiple instruments based on tar get identification by a sensor The target at first is found and defined in comparison to the sensor in its local reference frame To find the independent position a similar algorithm shall be used as in the airborne image mapper that transforms the location into world reference frame Later when the scientific instruments shall be pointed at the target the location is transformed
98. systems use WGS 84 The two standards use different reference ellipsoids the ETRS 89 uses GRS1980 while the WGS 84 has its own reference ellipsoid named WGS 84 Since the coordinates of the target points are most likely to be obtained by the use of a map ETRS 89 is used for the definition of the ellipsoid According to Geographic information Spatial referencing by coordinates 2003 the parameters for a and b defined by the GRS1980 reference ellipsoid are a 6378137 0 m semimajor axis of ellipsoid 5 3 b 6356752 3 m semiminor axis of ellipsoid X and X are defined as the vectors from the centre of Earth to P and P expressed with Cartesian coordinates Then the vector between the two points expressed in Cartesian coordinates is X X X Figure 5 2 Global and local level coordinates Figure adapted from Hofmann Wellenhof et al 2001 27 To transfer the vector into the local level reference frame first the axes of the IWRF shall be found in global level Cartesian coordinates XYZ The point of origin for IWRF in global level geodetic coordinates is known the position of instrument The vectors n e and u need to be found that define the directions true North n East e and Up u See Figure 5 2 Illustrated in Figure 5 2 and according to Hofmann Wellenhof et al 2001 these vectors are defined by sin y cos A sin A cos p cos A n sin y sin A e cos Ai u
99. t of pointing for the yaw angle calibration marked by the red circle The green arrow marks the direction of pointing The map used in the image is the property of the Norwegian Polar Institute Norwegian Polar Institute 2014 la Figure 6 3 Pictures taken of the first target see fig 6 2 during the yaw calibration in the order 26 28 and 30 for initial yaw The target is marked with a red circle in each picture it is visible in 36 7 file A 15 48 0 0 se gt Figure 6 4 The second calibration target Adventstoppen The centre of the image taken by the Tracker Camera is marked by the orange cross while the targets on both images are marked by the red circles The map in the image is the property of the Norwegian Polar Institute Norwegian Polar Institute 2014 Figure 6 5 The third validation target Hiorthhamn The centre of the image taken by the Tracker Camera is marked by the orange cross while the targets on both images are marked by the red circles The map used in the image is the property of the Norwegian Polar Institute Norwegian Polar Institute 2014 6 2 2 Pitch and Roll calibration The roll and pitch can be measured with the use of a level on the instrument platform The precision required for the calibration is based on the accuracy of the motion for the instruments as it shall not be lower The accuracy for both the Narrow Field of view sCMOS camera and the Fs Ikea is 0 05 while for instrument
100. ting for the instrument in Instrument World Reference Frame The result then is transformed it into the Pointing System Reference Frame 25 5 1 Geo Pointing The geo pointing control of the instrument is based on an algorithm that finds the vector between two points defined by their global level geodetic coordinates The input for this type of control is the geodetic coordinates of the target requiring the coordinates of the instrument to be known Finding the coordinates for the system is a calibration step see Chapter 6 The control of the motors is based on azimuth and elevation angles Therefore all vectors calculated in Cartesian coordinates shall be represented in spherical coordinates for the commands of the system The steps for the geo pointing control are the following 1 Calculate vector between the two given points in IWRF Instrument and Target in Cartesian coor dinates 2 Represent the same vector in PSRF 3 Transform the representation of the vector from Cartesian coordinates to spherical coordinates 5 1 1 Calculating the vector between points defined by geodetic coordinates Two points are considered noted by P and P defined by their global level coordinates p ellipsoidal latitude A ellipsoidal longitude h altitude The aim is to calculate the vector between these two points noted by xij expressed by the nj e and u in the IWRF a local level reference frame The approach used is to first cal
101. ue Command not a valid number getlat lat end 64 Example for an application specific function may be seen in Listing F 4 This function transforms geodetic coordinates into Cartesian coordinates Listing F 4 Function for the change of geodetic coordinates into cartesian coordinates Change geodetic to cartesian coordinates P 279 from B Hofmann Wellenhof H Lichtenegger and ZJ Collins GPS Theory and Practice Fifth edition SpringerWienNewYork 2001 function TPTU46TrackerF ToCartesian input Geodetic Cartesian var a b real Semi major and semi minor axis of ellipsoid N real Radius of curvature begin WGS 84 parameters a 6378137 0 b 6356752 3 Calculate radius of curvature N axa sqrt axa x cos input lat cos input lat bxb sin input lat sin input lat Calculate Cartesian coordinates ToCartesian X Ntinput alt cos input lat cos input lon ToCartesian Y N tinput alt cos input lat sin input lon ToCartesian Z b b axa N input alt sin input lat end 65 The function labelled with Command from Client shown in Listing F 5 is the procedure called when a new string appears in the TCP socket This is the part of the code that differs from server to server In the followings a short walk through of the procedure and explanations about one of the commands are presented The procedure first verifies whether
102. ue at the middle of the lens is determined To determine the projection equation for the lens images are recorded with 640 x 512 pixels resolution while turning the arm from the centre towards the horizons with 10 steps except for when the source reaches the horizon that step is only 7 5 The process is repeated two times to compensate for adjustment errors and the values are averaged All angle values measured are adjusted according to the 0 75 cm spatial offset of the rotation point of the tripod from the centre of the lens Figure 6 6 shows some of the calibration images for the fish eye lens The images start with the light source in the centre image A then it moves towards the left horizon Image B is taken with the light source moved 10 to the left Images C and D are the last two steps right before and on the horizon 38 A 15 25 49 B 15 26 07 A 15 29 27 Figure 6 6 Examples for images recorded during the calibration of the fish eye lens note the images are colour inverted The light source is marked with a red circle in each picture 39 6 3 1 Compensation for spatial displacement Figure 6 7 is a sketch of the calibration equipment set up the centre of the lens is placed in point O the rotational axis of the tripod is placed in point B The light source is in point C moved there from point A It is clearly visible that the angle displacement read from the panning module of the tripod a is different from the a
103. us section and related parts in Chapter 5 In order to be able to apply them the vector shall be expressed with Cartesian components the equations for the transformation are given in Chapter 5 14 2 3 SvalTrack II The SvalTrack II software see Sigernes et al 2011 developed at UNIS is a sky observer program It implements different models for the determination of the auroral oval information about celestial bodies and satellites It is a real time software updating the information about all the previously mentioned in each second providing azimuth and elevation information about them from the geographic position of the program subject to user setting Satellite information is extended with their altitude as well This program is used as another possible instrument control interface of the SvalPoint As it does not use any sensor for target acquisition it is considered to be a mathematical control interface and henceforth it is referred to as such See Figure 2 3 for screen captures of the software s graphical user interface Local Sky View Obect Dela Constellation Cap Bayer p Plomsteed 5 HD 2032 0 BSC 8162 Magnetud 2 44 Spectral Class AT 84 Color nde O22 RA 319 65 DEC 62 59 Elevation 56 27 Azimuth 49 69 Coratelyion Uisa Major Stat Catalogue BSCS Magnhude 6 50 Azimuth amp Elevation 272 169 4 551 Local Sky View List of Satelites Selected Object Moon M M1 GEDEYE 1 a C
104. utm grid GPS World 32 Thorlabs 2011 V21 photonics catalog Wasmeier P 2006 Geodetic transformation toolbox http www mathworks se matlabcentral fileexchange 9696 geodetic transformations toolbox Accessed 2014 05 09 Whiter D K Gustavsson B Partamies N amp Sangalli L 2013 A new automatic method for es timating the peak auroral emission height from all sky camera images Geoscientific Instrumentation Methods and Data Systems 2 1 131 144 77
105. valPoint has been validated entirely from the connection s point of view and all tests have passed The validation of the pointing on the other hand has been performed only partially This is due to both the light conditions in the time frame in which the thesis work took place and for a technical failure on site that has not been solved in the time limit One of the motor controllers on the Fs Ikea instrument have failed therefore its pointing could not be tested textual output about the control angles has been verified in its case The other reason for the partial validation is that dark sky returns in September a time until which this project does not extend therefore stars satellites and the aurora are not visible Also at the time of the validation there was no suitable time for testing on the moon as it has always been very close to the horizon Until the present moment test 1 and a part of test 2 has been conducted Test 1 Due to the mathematical nature of the method the geo pointing is the most accurate pointing and the test associated to it is rather a validation of the calibration values than of the method the geo pointing is also actively used in the calibration see Chapter 6 Actual test on the method were done only in order to make sure that all formulas are correct in the program This has been done by approximative pointing at a number of different targets The targets chosen have been geographical features easily identifiable fro
106. w Including the translation with T the final form of the equation for the transformation is TpsrF Q V Qy 9 Qulo wre T 5 7 28 5 1 3 Representing a vector in spherical coordinate system After calculating the vector xpgrr the vector representation shall be transformed into spherical coordi nates as the commands to the pointing system are azimuth and elevation values See Figure 5 3 for the illustration of the problem The axes of the PSRF are named n u and e for the optical axis up and the axis complementing it to a left handed system Figure 5 3 Measurement quantities in the PSRF Adapted from Hofmann Wellenhof et al 2001 As described in Hofmann Wellenhof et al 2001 given the components nj e and uj the azimuth w and elevation y angles can be calculated as follows S F 5 8 eae a Es ea MN Vi 3 arccos AP E By a T Analysing Equation 5 8 furthermore it can be noticed that in case both the n and e components of the vector are negative the azimuth angle is ambiguous the ratio of e and n is positive and the calculated angle is the azimuth for the mirrored image of the vector Similar problem arises when the n is negative and e is positive The same angle results as if the signs are the other way around It can be concluded that these equations give correct results only in case n is positive Therefore the cases when the vector has a negative n component are distinguish
107. ware interactions One of the most important features of the system is that its design leaves room for further development After the real test of the system new programs may be developed especially on the client side for tar get identification Features such as image processing for the automatic identification of aurora and the scanning of its entire area or the mounting of instruments or sensors on truck aircraft or other moving platforms with sensors to determine their changing attitude or mobile phone application based remote control are all possible to be developed Also further sensors or instruments may be added with little effort placed at very different locations extending all the way to the mainland 50 Further helpful software applications for making the use of SvalPoint easier would be the ones that help calculating the height of the target and determining the value that shall be the input for the system As discussed in Appendix C the determination of the height of aurora is a complex problem in itself therefore to be able to do it at a time scale suitable for the observations an automated software is absolutely necessary Furthermore as shown in Section 7 1 when the height is estimated with a given uncertainty in order to have the smallest possible errors a different value shall be entered in the system than the estimation This value can be calculated for each estimation therefore an option for it in the control interface woul

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