Servo System User Manual
Contents
1. An algorithm calculating the shift of the lower u joint coordinates due to distortion of the telescope base due to temperature A compensation algorithm for deformations of the telescope including platform depending on the actual position This compensation is derived from error tables generated during pointing calibration measurements AAza APOlerr A compensation algorithm for RF refraction AElrefract A compensation algorithm for optical refraction required only for alignment measurements using an optical pointing telescope AElretract A compensation algorithm for misalignment of the optical pointing telescope AAZopt AE lopt The actual corrections are displayed at the PTC Local User Interface The individual compensations can be enabled and disabled separately at the PTC Local User Interface or from remote by the station computer 3 1 2 Combination of Error Terms The Pointing Computer will transfer the sum of all enabled corrections to the ACU separately for jack related and telescope level corrections ALiot Alpi Alii AL AAZiot AAZerr AAZopt AE het AEler AElopt AElretract APolicot APOlerr page 6 NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT BE DISCLOSED WITHOUT THE WRITTEN CONSENT OF VERTEX ANTENNENTECHNIK GmbH DUISBURG VERTEX ANTENNENTECHNIK GMBH Doc No OM1002114 21320 Version 1 3 The ACU will apply the corrections as follows2. Doc No VERTEX ANTENNENTECHNIK GMBH OM1002114 21320 Version 1 3 mov vector of the upper movable point of the jackscrew with mov xmi ymi zmi i 1 6 L Jackscrew length with Li i 1 6 dv1 manually pre set translation movement normally dv1 0 0 0 mm dv2 automatically translation movement to reduce the travel ranges of the universal joints 90 o die pl ld t P9 costou 90 Canin 0 sin o emie max 0 optimized parameter 850 mm Omax 60 dv total translation movement with dv az zen dv1 dv2 az zen 1 0 0 rotation matrices Rx a 0 cos a sin a 0 sin a cos a cos a 0 sin a Ry a 0 1 0 0 cos a cos a 0 Rz a cos a 0 0 0 1 The kinematics can be different in the forward and backward transformation Beside the topology data the forward transformation needs the angles az zen po and the translation movement dv1 as input data and yields the jackscrew lengths Li i 1 6 while the backward transformation needs the jackscrew lengths Li i 1 6 as input data and yields the angles zen poi and the translation movement dv1 The global coordinate system of the telescope together with the sky orientation is shown in Fig 2 assuming that the mount is orientated to due North page 3 NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT BE DISCLOSED W
3. Poln measured pointing error Azr AZn Ele Ely Pole Poly page 14 NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT BE DISCLOSED WITHOUT THE WRITTEN CONSENT OF VERTEX ANTENNENTECHNIK GmbH DUISBURG VERTEX ANTENNENTECHNIK GMBH Doc No OM1002114 21320 Version 1 3 Transform measurement data by an irregular grid to an regular grid calculation for an regular grid azimuth area degree 0 00 360 00 step 5 00 elevation area degree 30 00 90 00 step 5 00 polarisation area degree 25 00 10 00 step 5 00 measurement data irregular grid Az El Pol dAz dEl dPol 0 00000000 30 00000000 30 00000000 1 00000000 1 00000000 1 00000000 20 00000000 30 00000000 30 00000000 5 00000000 1 00000000 2 00000000 40 00000000 30 00000000 30 00000000 4 00000000 1 00000000 3 00000000 60 00000000 30 00000000 30 00000000 3 00000000 1 00000000 4 00000000 80 00000000 30 00000000 30 00000000 6 00000000 2 00000000 6 00000000 160 00000000 30 00000000 30 00000000 3 00000000 7 00000000 4 00000000 180 00000000 30 00000000 30 00000000 4 00000000 2 00000000 1 00000000 200 00000000 30 00000000 30 00000000 6 00000000 3 00000000 4 00000000 220 00000000 30 00000000 30 00000000 7 00000000 4 00000000 5 00000000 100 00000000 30 00000000 30 00000000 7 00000000 3 00000000 7 00000000 120 00000000 30 00000000 30 00000000 3 00000000 4 00000000 2 00000000 140 00000000 30 00000000 30 00000000 2 00000000 6 00000000 3 00000000 Table 5 Un
4. 0 Calibration temperature is 17 so AT Tseng 17 With the position of the sensors Psens1 122 0 Psens2 1250 0 Psens3 L and the readouts of the temperatures at the sensors the results of the module temperature correction are the correction lengths ALi page 11 NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT BE DISCLOSED WITHOUT THE WRITTEN CONSENT OF VERTEX ANTENNENTECHNIK GmbH DUISBURG VERTEX ANTENNENTECHNIK GMBH Doc No OM1002114 21320 Version 1 3 3 2 4 Jackscrew Rotation Error Each jackscrew spindle rotates with the angle p see also Fig 6 relative to the jackscrew nut when tilting and rotating the telescope mount Because of the spindle thread a jackscrew length change can occur which is not detected by the encoder on the still standing worm gear shaft This influence is calculated by a mathematical algorithm derived from the kinematics of the jackscrew at any position my Bax 2 movable point jackscrew fix point fx By Fig 6 Rotation of the jackscrew Each jackscrew kinematics consists of the five degrees of rotations Bix Bmx Bmy and pz A special algorithm calculates the essential data B With a jackscrew pitch of p 20 mm rotation and the basis rotation angle pasis is equal to Bz in the hexapod basis position the jackscrew length error by rotation of the jackscrew against the fixed nut is AL
5. ANTENNENTECHNIK GmbH DUISBURG VERTEX ANTENNENTECHNIK GMBH Doc No OM1002114 21320 Version 1 3 The correction software calculates by interpolation the position errors and A pol as a function of the present telescope position Therefore the regular grid has a great computer time advantage adverse the irregular grid The linear interpolation algorithm searches the cube of the neighbouring positions in the grid which encloses the actual position and interpolates the position errors assigned to each corner of the cube The file inter dat must contain identical lines for Az 0 deg and Az 360 deg The telescope error model yields position corrections AAZerr AElerr and APOlerr page 16 NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT BE DISCLOSED WITHOUT THE WRITTEN CONSENT OF VERTEX ANTENNENTECHNIK GmbH DUISBURG VERTEX ANTENNENTECHNIK GMBH Doc No OM1002114 21320 Version 1 3 Calculation for an regular grid azimuth area degree 0 0000 360 0000 step 5 0000 elevation area degree 30 0000 90 0000 step 5 0000 polarisation area degree 25 0000 10 0000 step 5 0000 Az El Pol dAz dEl dPol 0 00000000 30 00000000 25 00000000 0 06819019 0 00858209 0 00000000 0 00000000 30 00000000 20 00000000 0 06818528 0 00858367 0 00000000 0 00000000 30 00000000 15 00000000 0 06818039 0 00858527 0 00000000 0 00000000 30 00000000 10 00000000 0 06817552 0 00858688 0 00000000 0 00000000 30 0000
6. Hx and Hy can be entered at the PTC Local User Interface see part 3 of this manual The correction algorithm yields position corrections AAZopt and AElop There is no error in polarization Formula provided by ASIAA page 19 NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT BE DISCLOSED WITHOUT THE WRITTEN CONSENT OF VERTEX ANTENNENTECHNIK GmbH DUISBURG VERTEX ANTENNENTECHNIK GMBH Doc No OM1002114 21320 Version 1 3 3 3 5 Optical Refraction Model The optical refraction is required only for alignment measurements using an optical pointing telescope During normal operation this refraction should be disabled Enabling disabling is only possible at the PTC Local User Interface Correction formula 60 101 tan ZD 0 0668 tan ZD PMB 283 15 A 1 2 ee 180 pi 3600 10132 TDK TDK Ambient temperature K PMB Atmospheric pressure mbar ZD Distance from zenith rad 90 degr 1 180 The formula yields REF in radians page 20 NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT BE DISCLOSED WITHOUT THE WRITTEN CONSENT OF VERTEX ANTENNENTECHNIK GmbH DUISBURG VERTEX ANTENNENTECHNIK GMBH Doc No OM1002114 21320 Version 1 3 This page intentionally left blank page 21 NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT BE DISCLOSED WITHOUT THE WRITTEN CONSENT OF VERTEX ANTENNENTECHNIK GmbH DUISBURG
7. Record Release 1 2 Sep 2005 page 5 Release 1 3 May 2006 par 3 1 2 par 3 3 2 par 3 3 3 par 3 3 4 par 3 3 5 handling of mount rotation changed handling of u joint coordinates added description of error application in ACU modified sign definition added formula for calculation of water vapour pressure added modified formula for OPT correction new paragraph optical refraction correction page iii NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT BE DISCLOSED WITHOUT THE WRITTEN CONSENT OF VERTEX ANTENNENTECHNIK GmbH DUISBURG VERTEX ANTENNENTECHNIK GMBH Doc No OM1002114 21320 Version 1 3 1 INTRODUCTION 1 1 Purpose of this Manual This section of the Servo System User Manual contains a description of the pointing error model of the Hexapod Telescope at Mauna Loa Hawaii The pointing error model is used to eliminate known systematic pointing errors caused by non linearities deformations temperature variations etc A description of the hexapod kinematics is contained as well The compensation algorithms themselves are implemented in the Pointing Computer PTC Any accessible parameters can be modified at the PTC see part 3 of this User Manual description of PTC Local User Interface 1 2 Software Identification This Error Model Description describes the algorithms as implemented in the PTC software version M1002114P 2 7 1 3 Acronym List ACU Antenna Control Unit
8. a Actual jack length Lact Lact L meas b Commanded hexapod position 2 forTransformation 2 nominal AAZiot Elcmd_forTransformation nominal Polcma torTranstormation Polcmd nominal APOltot c Actual hexapod position AZtrue AZirom transformation AAZiot Elirue Elirom_transformation AE hot Polirue POltrom_transformation APolio This actual position is displayed at the ACU and reported as actual position to the STC This means that the actual position always is the real position after applying all corrections and not the uncorrected mount position 3 2 Corrections on Jack Level 3 2 1 Overview The corrections on jack level consist of the compensations for jackscrew pitch error temperature compensation jack length measuring error depending on telescope position due to rotation of upper u joints support cone deformation due to temperature All this corrections except support cone correction yield jack length corrections AL for each of the jackscrews 1 6 On the other hand the special case effects coordinate change of the lower universal joints which also can be interpreted as a length change of the jackscrews All modules are described in the following chapters page 7 NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT BE DISCLOSED WITHOUT THE WRITTEN CONSENT OF VERTEX ANTENNENTECHNIK GmbH DUISBURG VERTEX ANT
9. ag 2 423328419428810 1022 1 739067723782910 1072 6 948301798710590 1072 as ag 2 285716445585560 1079 3 372908043046730 107 8 991790206208470 10 9 aio 7 708311059986410 10 2 432377395612230 10 4 932382220905220 10 aio Table 3 Vector a for each jackscrew Finally the measurement curves must shifted depending on of the real jackscrew mm and the characteristic measurement data see Fig 4 C1 C2 C3 C4 C5 jackscrew length reference switch measurement limit extended jackscrew measurement retracted jackscrew movement of the curve with C5 f C2 so that the jackscrew pitch error can be calculated by AL mm f L C1 C2 C5 10 length L page 9 NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT BE DISCLOSED WITHOUT THE WRITTEN CONSENT OF VERTEX ANTENNENTECHNIK GmbH DUISBURG VERTEX ANTENNENTECHNIK GMBH Doc No OM1002114 21320 Version 1 3 jackscrew pitch i 226 76 11496 Z Y Measurement range Measurement curve Fig 4 Jackscrew with measurement curve The measurement curve is situated in the range of C4 L C1 C2 C3 The data C1 C5 are listed in Table 4 C1 mm C2 mm C3 mm C4 mm C5 um 6150 366 36 624 19 1972 3359 1970 14 7324 6149 009 86 603 47 7033 3407 7029 427 2679 s ewoso ae Les ae Table 4 Correction factors for each jackscrew The coefficient vector a
10. is coded in the hexapod software and the correction variables C1 until C5 are stored in an external file This file has to be replaced along with the related jackscrew if a jackscrew needs to be exchanged The correction algorithm yields length corrections AL until page 10 NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT BE DISCLOSED WITHOUT THE WRITTEN CONSENT OF VERTEX ANTENNENTECHNIK GmbH DUISBURG VERTEX ANTENNENTECHNIK GMBH Doc No OM1002114 21320 Version 1 3 3 2 3 Temperature Compensation The varying temperature of the different jackscrews with the length L produces a length change AL of each jackscrew compared to the length at calibration temperature Taking into account the material specific thermal expansion coefficient o 12 0 10 1 K and the temperature difference AT between the individual jackscrews which will be measured and averaged by three temperature sensors Psens1 AT 1 Psens2 AT2 Psens3 along the jackscrew see Fig 5 L jackscrew Psens1 Psens2 Psens3 Fig 5 Jackscrew with temperature sensors the length change results approximately in a linear temperature characteristics function ATI x P sensl AT2 ATI AT AT2 P P P x P Se P sensl lt x lt P ud fO AT ATO ar PRO P Y X E sens P nd x Pons Pd sens2 P zeng Pu x Psi AT3 Pons Page to AL f x dx f x dx fa f x dx
11. 00 10 a a 3 175818812949300 10 1 279223138765940 10 5 333730182112170 10 a 1 000966699300860 10 2 079059533885010 10 1 767559120263330 10 a4 1 541352099930610 10 6 590341383524090 10 2 504907224531590 10 as 1 387921160762620 107 9 238622036561910 10 2 285806763018910 10 as 7 764892416501680 10 7 095505201937470 10 1 446531162237440 10 a 2 743812116375030 10 3 198287869016120 107 6 245759670530750 1079 a 5 973058848219020 1022 8 457849525584240 10 1 714087876766300 107 as ag 7 325619589449050 10 1 217131472371950 10 2 645713864558710 10 9 ag 3 877049825835910 10 7 368087558944830 10 1 731246066850530 10 aio a jackscrew 4 jackscrew 5 jackscrew 6 a ao 2 743324175636780 107 9 120596249290690 107 8 464647627231470 10 ao 1 816390007961940 10 2 994017883033060 10 1 399391192743870 10 a a 2 040482864105740 10 1 853475595088450 10 1 296102525136170 10 a 6 306703070241420 10 4 707048964999170 10 5 695909876093460 10 as 9 461016317632950 10 5 301560895763430 10 1 109389698870550 10 as 8 105379713701580 10 2 787891685747700 10 1 187703984708340 10 as 4 193397675987190 1075 3 403289908214870 1079 7 580116027803620 1075 ac 1 820217138374700 10 3 342955508378500 10 2 961352291320270 107 a
12. 0000 5 00000000 0 06817067 0 00858849 0 00000000 0 00000000 30 00000000 0 00000000 0 06816586 0 00859011 0 00000000 0 00000000 30 00000000 5 00000000 0 06816108 0 00859174 0 00000000 0 00000000 30 00000000 10 00000000 0 06815635 0 00859336 0 00000000 0 00000000 35 00000000 25 00000000 0 06829306 0 00857819 0 00000000 0 00000000 35 00000000 20 00000000 0 06828835 0 00857977 0 00000000 0 00000000 35 00000000 15 00000000 0 06828363 0 00858136 0 00000000 0 00000000 35 00000000 10 00000000 0 06827888 0 00858296 0 00000000 0 00000000 35 00000000 5 00000000 0 06827412 0 00858458 0 00000000 0 00000000 35 00000000 0 00000000 0 06826935 0 00858620 0 00000000 0 00000000 35 00000000 5 00000000 0 06826458 0 00858782 0 00000000 0 00000000 35 00000000 10 00000000 0 06825981 0 00858946 0 00000000 0 00000000 40 00000000 25 00000000 0 06839662 0 00857429 0 00000000 0 00000000 40 00000000 20 00000000 0 06839212 0 00857586 0 00000000 360 00000000 85 00000000 25 00000000 0 11690180 0 00683586 0 00000000 360 00000000 85 00000000 20 00000000 0 13483681 0 00670948 0 00000000 360 00000000 85 00000000 15 00000000 0 16171136 0 00655411 0 00000000 360 00000000 85 00000000 10 00000000 0 20329068 0 00648106 0 00000000 360 00000000 85 00000000 5 00000000 0 28139628 0 00676227 0 00000000 360 00000000 85 00000000 0 00000000 0 37440990 0 00703623 0 00000000 360 00000000 85 00000000 5 00000000 0 28172032 0 00677584 0 00000000 360 00000000 85 00000000 10 00
13. 000000 0 20456258 0 00656923 0 00000000 360 00000000 90 00000000 25 00000000 0 12713996 0 00680790 0 00000000 360 00000000 90 00000000 20 00000000 0 14697311 0 00664064 0 00000000 360 00000000 90 00000000 15 00000000 0 17562134 0 00644921 0 00000000 360 00000000 90 00000000 10 00000000 0 21738251 0 00631872 0 00000000 360 00000000 90 00000000 5 00000000 0 27689824 0 00643678 0 00000000 360 00000000 90 00000000 0 00000000 0 31867511 0 00665926 0 00000000 360 00000000 90 00000000 5 00000000 0 27740887 0 00645507 0 00000000 360 00000000 90 00000000 10 00000000 0 21882686 0 00639312 0 00000000 Table 6 Sample file inter dat page 17 NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT BE DISCLOSED WITHOUT THE WRITTEN CONSENT OF VERTEX ANTENNENTECHNIK GmbH DUISBURG VERTEX ANTENNENTECHNIK GMBH Doc No OM1002114 21320 Version 1 3 3 3 3 RF Refraction Correction PTC also compensates for atmospheric radio refraction Enabling disabling is possible at the PTC Local User Interface The algorithm used is taken from Astrophysical Quantities by C W Allen 8rd edition page 124 andis N 1 7 8e 5 P 0 39 e T T N N 1 2 N N lrefract refO tan alt where P atmospheric pressure in mb hPa e water vapour pressure in mb hPa T temperature in Kelvin alt altitude The correction AElrefract is to be added to the true altitude to give the apparent altitude Actual weather data
14. Az Azimuth EI Elevation EMI electromagnetic interference HPC Hexapod Computer ICD Interface Control Document LCP Local Control Panel LUI Local User Interface PCU Portable Control Unit PLC Programmable Logic Controller PTC Pointing Computer STC Station Computer page 1 NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT BE DISCLOSED WITHOUT THE WRITTEN CONSENT OF VERTEX ANTENNENTECHNIK GmbH DUISBURG VERTEX ANTENNENTECHNIK GMBH Doc No OM1002114 21320 Version 1 3 2 HEXAPOD KINEMATICS The kinematics of the AMIBA telescope is a mathematical optimized kinematics of hexapod structure which is shown in Fig 1 Platform Center of Gravity Upper Universal Joints Jackscrew Universal Joints Fig 1 Hexapod coordinate system and mount parameters The kinematical equation of the hexapod structure is 1 Rz o Rz p Rz o mov v v av fix i 1 6 with the notations az azimuth angle zen zenith angle zen 1 2 with elevation angle pol hexa pol polarisation angle alternatively obs pol polarisation angle pol Obs Ppol Paz vector of the rotation point D with v 0 0 3580 mm fix vector of the lower fixed point of the jackscrew with fix xfi zf 1 1 6 page 2 NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT BE DISCLOSED WITHOUT THE WRITTEN CONSENT OF VERTEX ANTENNENTECHNIK GmbH DUISBURG
15. ENNENTECHNIK GMBH Doc No OM1002114 21320 Version 1 3 3 2 2 Jackscrew pitch error The telescope positioned is determined by measuring the positions of the six jackscrew actuators Since not the real length of the jackscrews is measured but only the rotation any jack pitch error e g machining errors non linearities etc directly leads to a telescope positioning error In order to be able to compensate for this error each jackscrew has undergone an in plant calibration measurement A correlation function see Fig 3 between the linear movement of the jackscrew and the encoder readout has been derived for each jackscrew Jackscrew pitch jackscrew pitch um 3400 2900 2400 1900 1400 300 400 length mm Fig 3 Error curves for jackscrew pitch Each measurement curve in Fig 3 can be described by a polynomial of the order 10 in the 1 form f x x The vector a of the coefficients for each jackscrew is listed in Table i I 8 NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT DISCLOSED WITHOUT THE WRITTEN CONSENT OF VERTEX ANTENNENTECHNIK GmbH DUISBURG VERTEX ANTENNENTECHNIK GMBH Doc No OM1002114 21320 Version 1 3 a jackscrew 1 jackscrew 2 jackscrew 3 a ao 2 024509761765160 10 4 254599813289640 102 1 424616467483780 10 ao 4 690421834325520 10 2 015506873855310 10 3 0141223680168
16. IK GMBH Doc No OM1002114 21320 Version 1 3 3 3 Corrections on Telescope Level 3 3 1 Overview The corrections on telescope level consist of the compensations for error model for telescope and platform deformations compensation algorithm for RF refraction compensation algorithm for optical refraction All this corrections except support cone correction yield position corrections Agel and A pol 8 3 2 Telescope Error Model The idea of the telescope correction mode is to measure the telescope position errors and Apa at different points on the sky by astronomical observation of well known targets All measurement points together make up a measurement grid For positions between the data points the delta positions can be calculated by interpolation For each data point the hexapod position Az El Pol and the measured pointing errors dAz dEl dPol are entered into a file named inter un dat see sample file in Table 5 The measurements make up an irregular grid of one sector of the sky For a good pointing accuracy both the sector size and the number of measurements should be as large as possible In addition the measurements should be made at different polarisations Definition of sign of pointing error Nominal position of object AZn Eln Poly The object has been found at position display at Azp Ele Polr Error to be entered into table at position Azw Ely
17. ITHOUT THE WRITTEN CONSENT OF VERTEX ANTENNENTECHNIK GmbH DUISBURG VERTEX ANTENNENTECHNIK GMBH Doc No OM1002114 21320 Version 1 3 north AZ 0 fixed point of 7 the jackscrew east AZ 270 west AZ 90 south AZ 180 Fig 2 Orientation of Hexapod Mount The theoretical coordinates of the jackscrew points which are given by an mathematical optimization calculation are listed in Table 1 lower universal joints variable fix upper universal joints variable mov ex sm sme Drm Li mese wraomr meer T Brener Lx p meer mesa Leer aranes 3 R2 R2 R1 n R1 sin 141 22 1 R1 cos 1599 Ri sin 159 2 cos 230 R2 sin 2309 00 R1 cos 2619 Table 1 Theoretical jackscrew points with R1 1550 0 R2 1850 0 The real coordinates of the jackscrew points have been measured during in plant installation of the telescope in may 2004 in Duisburg Germany by VERTEX As a result of fabrication tolerances the actual coordinates differ slightly from the theoretical ones They are listed in Table 2 lower universal joints variable fix upper universal joints variable Jack x mm y mm z mm x mm y mm z mm 1822 8350 320 5483 00 Ri cos 219 R1 sin 219 6324422 17380707 00 Rt cos 39 Rt sin 39 633 0782 1737 6624 00 1 141 Rt si
18. RS Se The algorithm is coded in the hexapod software and the results are the correction lengths AL AL e page 12 NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT BE DISCLOSED WITHOUT THE WRITTEN CONSENT OF VERTEX ANTENNENTECHNIK GmbH DUISBURG VERTEX ANTENNENTECHNIK GMBH Doc No OM1002114 21320 Version 1 3 3 2 5 Support Cone Compensation Mode The coordinates of the 6 lower fixed universal joints has been measured during in plant assembly of the AMiBA Telescope in May 2004 at an ambient temperature of 17 C The x and y coordinates vary with the temperature of the support cone This error is taken into account by the formulae Xnew X a T To Ynew y a T To with the notations a specific thermal expansion coefficient with o 12 0 10 1 K T average value of the temperature which is measured by several sensors at the cone To basis measurement temperature of 17 C X y coordinates of the lower fixed universal joints see Table 2 page 5 Together with the readout temperatures at the sensors and the original x y coordinates of the lower universal joints at a temperature of 17 C the results of the module support cone compensation mode are corrected x y coordinates for the 6 lower universal joints page 13 NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT BE DISCLOSED WITHOUT THE WRITTEN CONSENT OF VERTEX ANTENNENTECHNIK GmbH DUISBURG VERTEX ANTENNENTECHN
19. VERTEX ANTENNENTECHNIK GmbH Ein Unternehmen der General Dynamics Gruppe TELESCOPE HEXAPOD MOUNT Servo System User Manual Part 9 Pointing Error Model Vertex Document No OM1002114 21320 Version 1 3 2006 05 16 Name Signature Prepared Dr Dirk Libuschewski Structural Analysis OS r Klaus Willmeroth Systems Engineer Servo T 9 Dr Konrad Pausch Program Manager 01 5 0 insta Released Ralph Semmler Document Control 2006 0 22 7 Vertex Antennentechnik GmbH Baumstr 50 D 47198 Duisburg Phone 49 2066 2096 0 Fax 49 2066 2096 11 e mail info vertexant de www vertexant de NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT BE DISCLOSED WITHOUT THE WRITTEN CONSENT OF VERTEX ANTENNENTECHNIK GmbH DUISBURG VERTEX ANTENNENTECHNIK GMBH Doc No OM1002114 21320 Version 1 3 Table of Contents TETTE 1 541 due ttis 1 1 2 tte eh 1 E 1 2 Hexapod Kinematics xe ee ee ando eti ee eer 2 a Roning Error OGG ocu cune dni nig ahah es icu ce id date elc ho dde tec ttd ols 6 DE 1 01 eeh 6 3 1 1 Components of Pointing Error Model sss enne 6 3 1 2 Combination of Error ei 6 3 2 Corrections on Jack Level 7 KP EB TEE 7 2 2 2 JACKSCFEW e RT te 8 3 2 8 Temperature 11 3 2 4 J
20. ackscrew Rotation Emor nennen annt 12 3 2 5 Support Cone Compensation Mode 13 3 3 Corrections on Telescope Level ENEE 14 a n Lor tma rH NER mate ns 14 3 3 2 Telescope Error Mod l r i nonno d dui Oda d at Ee ra sd etu RE EAR 14 33 3 etie t 18 3 3 4 Misalignment of Optical Telescope 0000 00 19 3 3 5 Optical Retraction Model ettet dece teret do a eid te dete nets 20 page ii NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT BE DISCLOSED WITHOUT THE WRITTEN CONSENT OF VERTEX ANTENNENTECHNIK GmbH DUISBURG Doc No OM1002114 21320 Version 1 3 VERTEX ANTENNENTECHNIK GMBH VERTEX ANTENNENTECHNIK GmbH CONFIDENTIAL AND PROPRIETARY All computer software technical data or other information pertaining to the equipment covered by this document is considered proprietary by VERTEX ANTENNENTECHNIK GmbH Such information transmitted in this document or related documents is for the benefit of VERTEX ANTENNENTECHNIK GmbH customers and is not to be disclosed to other parties verbally or in writing without prior written approval of VERTEX ANTENNENTECHNIK GmbH Additionally this document may not be reproduced in whole or in part without written consent from VERTEX ANTENNENTECHNIK GmbH Update
21. can be transferred by the station computer to the PTC in order to keep the compensation as accurate as possible Calculation of water vapour pressure e from relative humidity e RH 100 ES ES Co 10 co where e water vapour pressure in mb hPa RH relative humidity in ES saturation pressure of water vapour in mb hPa Tc temperature deg C Co 6 1078 7 5 C2 297 3 1 Algorithms provided by ASIAA page 18 NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT BE DISCLOSED WITHOUT THE WRITTEN CONSENT OF VERTEX ANTENNENTECHNIK GmbH DUISBURG VERTEX ANTENNENTECHNIK GMBH Doc No OM1002114 21320 Version 1 3 3 3 4 Misalignment of Optical Telescope This correction is only required during observations with the optical pointing telescope It compensates for any misalignments of this device compared to the pointing direction of the main telescope The x y z right hand frame of an optical telescope is positioned on the platform whereas the z axis is normal to the platform and the y axis the reference line for 0 degree With the notations Hx angle in the x z plane rotation around the y axis for small angles it points along the x axis Hy angle in the y z plane the pointing correction angles are Hx cos Q F P pot Hy 0 9 4 AAz cos Q opt AEl Hy cos Q Pp Hx 9 4 opt The parameters
22. ier in this paragraph are mount related azimuth angles The mount related coordinates of upper and lower u joints are stored in an ASCII file on the CF memory cards of ACU PTC and HPC The coordinate files of all three computers must be identical at all times WARNING Any significant change in coordinates any typos or swapped digits may lead to severe damage of the telescope because collision situations could occur without being detected by software or hardware Utmost caution is needed when modifications to the geometry file s are required Such changes should only be modified by well trained and experienced staff The manufacturer cannot be held responsible for malfunctions and or any damage resulting from modification of the geometry file s page 5 NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT BE DISCLOSED WITHOUT THE WRITTEN CONSENT OF VERTEX ANTENNENTECHNIK GmbH DUISBURG VERTEX ANTENNENTECHNIK GMBH Doc No OM1002114 21320 Version 1 3 3 POINTING ERROR MODEL 3 1 Overview 3 1 1 Components of Pointing Error Model The pointing error model includes the following compensations Compensation curves for jackscrew pitch non linearities based on i plant calibration measurements for each jacks AL A compensation algorithm for jackscrew length variations due to temperature AL Acompensation for non measured length variations of a jackscrew due to rotation of the upper u joints
23. n 141 page 4 NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT BE DISCLOSED WITHOUT THE WRITTEN CONSENT OF VERTEX ANTENNENTECHNIK GmbH DUISBURG VERTEX ANTENNENTECHNIK GMBH Doc No OM1002114 21320 Version 1 3 lower universal joints variable fix upper universal joints variable Jack x mm y mm z mm x mm y mm z mm 1823 6568 320 3860 00 Rt cos 159 Rt sin 159 1191 2478 1416 5320 sgg 1 R1 cos 261 R1 sin 261 6 11909897 1417 3090 00 Rt cos 279 R1 sin 2799 Table 2 Actual coordinates of the jackscrew points with R121550 0 The mount installation on Mauna Loa differs from this symmetrical coordinates the Az 0 axes of the telescope as shown in Fig 1 does not point exactly to North but is rotated by several degrees This Azimuth offset is must be entered at ACU HPC and PTC as a parameter The following relationship applies AZsky AZmount Offsetaz Internally the coordinate transformations inside the three servo computer continue to use the telescope coordinate system Commands from user or superior computer was well as position displays show the azimuth related to the world coordinates The position commands are converted accordingly before being entered into the hexapod coordinate transformation AZmountcma AZsky cmd Offsets From this point of view all azimuth angles contained in definitions and formulae earl
24. sorted position measurements in file inter un dat The actual position for Pol in the both irregular and regular grids must always be entered as Hex Pol polarisation related to the hexapod mount After the measurements are done the irregular grid must be transformed into a regular grid and the result is saved in a file named inter dat see sample in Table 6 The file must contain the characteristic data of the regular grid in lines 2 4 as shown in the sample file This includes upper and lower limits of measured sector in Az El and Pol step size for regular grid in Az El and Pol The grid steps may be different for Az El and Pol The interpolation algorithm does not require a particular step size However the maximum number of lines in this file may not exceed 100 000 A possible mathematical algorithm to get a regular grid is known as Shepard method It can be used as stand alone software This method and of course all other mathematical methods is only effective inside the measurement sector Interpolations for positions outside the measurement sector may be inaccurate Activating the telescope error model correction requires a file inter dat This must be saved on the disk on the PTC flash card in the same directory as the executable software To read a new file inter dat the PTC must be re bootet page 15 NOTE THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION AND MAY NOT BE DISCLOSED WITHOUT THE WRITTEN CONSENT OF VERTEX
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