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ALASCA User Manual

1. It follows a list of parameter assignments Parameter Value where each assignment is placed in a separate line Section and parameter names are not case sensitive A semicolon at the first column indicates a comment Parameter values must be entered without units The expected units are shown in the table below Distance Offset Angle f km h To Boolean parameters TRUE or FALSE can be assigned Chapter 6 Object tracking 42 6 3 2 Section Parameter In this section a number of parameters can be set that define the behaviour of the AppBase application and the object tracking Most of the parameters for the tracking can also be set with the CAN interface see CAN specification for details The following lists describe the parameters using the scheme parameter name default value explanation AutoStart TRUE Start connected sensors automatically when AppBase starts SensorUpsideDown TRUE Mounting direction of the sensor s TRUE Sensor is mounted upside down FALSE Sensor is mounted normally ARCnetBaudRate 5M Baud rate of the ARCnet transmission SM 5 MBit s 10M 10 MBit s AppBaselD 6 ARCnet ID of the AppBase ECU on the ARCnet bus Must be between 1 and 255 and must be unique on the bus CANBaudRate 1 Baud rate of the CAN transmission 1 1 MBit s 2 500 kBit s CANBaselD 0x04F0 Base ID of the CAN output must be between 0x0001 and Ox07FE The following CAN id
2. ww 6 cm unobstructed optical path height A gt 229 vertical tilt angle Fig 19 Illustration of the unobstructed optical path required in the vertical direction As true for any optical device the ALASCA must work in a clean and dry environment The automotive integration chamber must be designed to provide this function At least the upper part of the ALASCA scanning part with mirror and scan motor unit must be contained within this chamber in order to provide dust free and moisture free operation The lower part of the ALASCA is already designed waterproof and equipped with a Gore Tex breather Upon customer request the ALASCA may be equipped with a flexible seal at the interface between its lower and upper part see Fig 20 which allows a waterproof connection of the integration chamber to the ALASCA scanning unit The integration chamber should also be equipped with a Gore Tex breather in order to avoid the intake of water during changes of air pressure The breather must be located in a position where water cannot accumulate It is extremely important for the functioning of the ALASCA that the inner of the integration chamber is finished with a black matt coating in order to minimise unwanted internal re flections The connection of the ALASCA to the vehicle body must withstand automotive requirements and should therefore be carried out with a sturdy design A mounting shoe should be designed permitting pitch angle ad
3. are all transmitted on the same port Since the data packet size on the Ethernet is limited the message may be spilt up into several packets This packet splitting is independent of the messages sent thus it 1s possible that the header of the next message is sent within the same packet as the end of the current message Since the message length is known from the header it is easy to find the beginning of the next message even if it is in the middle of a packet In case of a transmission error or data jam the magic word Ox AFFECOCO can be used to find the next message header just read data from the Ethernet until this byte sequence is received and you have got the start of the next message header AFFECOCO is a German play on words which means monkey Coco For decoding the different message types C source code 1s available from Ibeo Alternatively a self made parser can be constructed based on the following sections 4 7 3 Decoding object data An object data message has the file type 1 FILE_TYPE_OBJECTDATA It consists of a sequence of blocks with eight byte length each Each block is a copy of a CAN message All CAN messages of one object data message refer to the same scan For details about the individual CAN messages please refer to the document Ibeo CAN Specification 3 The theoretical maximum size of an object data message is 3 136 bytes 16 bytes header 390 x 8 bytes It is recommended to provide a buffer
4. ALASCA User Manual Version 2 0 0 2006 02 15 All rights reserved Published by Ibeo Automobile Sensor GmbH Fahrenkr n 125 22179 Hamburg Germany Internet www ibeo as de Telephone 49 40 64587 190 Fax 49 40 64587 109 Document information Title ALASCA User Manual Article number Authors J Scholz V Willhoeft Dr R Schulz T Kluge Date 2006 02 15 Text version 2 0 0 Copyright Ibeo Automobile Sensor GmbH 2006 The information contained in this Operating Manual is protected by copyright Copying or in any way reproducing the contents of this Operating Manual without the written consent of Ibeo Automobile Sensor GmbH is expressly prohibited If this document is used in an electronic format no changes may be made or the Ibeo logo removed Ibeo Automobile Sensor GmbH reserves the right at any time to modify the products described herein with a view to improving their operational reliability function and design Ibeo Automobile Sensor GmbH gives no guarantee as to the accuracy of this Operating Manual Any liability for direct or indirect loss or damage arising from the use of this Operating Manual is expressly excluded Ibeo Automobile Sensor GmbH accepts no liability for direct or indirect loss or damage arising from the use of the product This applies in particular to use of the products as described herein and to use of the products for purposes other than those for which they were designed Any informa
5. not connected Chapter 5 SyncBox 36 5 5 Signals of the SyncBox TTL and LED These signals are available on the bit I O connector of the SyncBox Ext_Sync_In bit VO Input s gnal for external synchronisation The trigger input mode only first low to high transition on this input will activate the bit I O mode Subsequent 1 ow to high transitions will cause a sync signal to be sent to the laserscanners The sync signal is acknowledged by a corresponding output on EXC SVC Vur Ext Synce in DoI bit I O Same as Ext_Sync_In but only each second double speed mode only 1ow to high transition will cause a sync signal trigger input For instance a camera that captures 25 frames s can synchronize a scanner with 12 5 Hz Ext Syne Out always Output signal A 5 ms high pulse is generated trigger output Ea every time a sync signal is sent to the laser SCanners EXt Sync Our Inv always Same as Ext_Sync_Out but with inverse polarity During sync this signal generates a low pulse Jitter_Warning_Out always Output signal valid only in bit I O mode If this jitter warning signal is high the input trigger applied at Ext_Sync_In has a time jitter of more than l ms and is not suitable for laserscanner synchronisation Synced Out 0 always The signal is high 1f the connected laserscanner Synced Out 1 on RS232 0 1 is synchronised Chapter 5 SyncBox 37 5 5 1 Timing example for timer mode
6. AEB is deactivated if the own velocity is slow In this situation no serious damage due to collisions is expected At such slow velocities AEB might also interfere with other applications like e g automatic parking The threshold is specified in m s using the parameter dEgoMinSpeed default 2 78 m s 10 km h 2 Ignore young objects The number of scans while an object has been tracked is called the object age AEB relevant objects must have a minimum age to be sure that their detection and tracking is stable The corresponding parameter is uMinObjectAge default 5 3 Ignore all objects that do not intersect with the driving path The driving path is defined as the area in front of the vehicle that has the same width as the vehicle and runs parallel to the x axis driving direction see in Fig 47 All objects that lie completely outside the driving path are ignored by AEB In other words only those objects are kept that have at Chapter 7 Software 57 least one scan point inside the driving path Use the parameter dVehicleWidth m to set the width of the vehicle The width does not include the side mirrors Default 1 75 m 4 Ignore remaining objects directly in front of the vehicle This filter is required to handle some rare situations Imagine a long crash barrier next to a narrow road While driving along the crash barrier it will be tracked as one object for a long time 1 e it will not be filtered by step 2 due to it
7. Fig 24 left e In this dialog first click on Internet Protocol TCP IP and then click on Properties e The Internet Protocol TCP IP Properties dialog appears Fig 24 right Write down the original settings shown in this dialog to restore them later e Click on the radio button Use the following IP address e Edit the four parts of the IP address The first three parts must be equal to the ones of the IP address of the ECU e g 10 152 10 see label at the ECU The last part must differ at your choice from the IP address of the ECU e Set the subnet mask to the same mask that is printed on the label of the ECU and close the dialog with the OK button e Note If firewall and or virus scanner software is running on the host PC this may cause some trouble when connecting to the ECU In this case try to disable the firewall and or the virus scanner temporarily Chapter 4 Electronic Control Unit ECU 25 Local Area Connection Properties 3 Kal Internet Protocol TCP IP Properties i ajx General Authentication Advanced General Connect using You can get IP settings assigned automatically iF your network supports this capability Otherwise you need to ask your network administrator ES Intel R PRO 1000 CT Network Conn Fab tie none ng This connechon uses the following items Obtain an IP address automatically EH Client for Microsoft Networks n ml Network Load Balancing ja File and Printer Sharing for M
8. Fig 27 The Ibeo application CD ROM contains this program To install the program start the FileZilla_x_x_xx_setup exe and follow the instructions Then start the program The following description is based on this program Other FTP programs work similarly Chapter 4 Electronic Control Unit ECU 26 2 Insert the IP address of the ECU the user name Administrator and the password Administrator in the three text fields Then click on the Quick connect button IP address User name Password FileZilla Connected to 10 152 10 105 File Edit Transfer View Queue Server Help in l Q 2 BER Adress posg adnate Password 7 Pot 21 L x Local Sile Remote Site HIR a EH user Ez eM Heer pn L l appe 532 DAT file 17 02 2005 15 11 no u Fap 630764 Anwendung 17 02 2005 13 33 E gt l appease ini 3470 Konfigurati 17 02 2005 15 11 Filename Filssize Filetype Last Modified La ja ppBase b T 388 DAT file 10 02 2005 09 59 3 Appe l KE Anwendung 10 01 2005 15 47 EKE Konfigurationse 09 02 2005 13 41 IF 3 files wit 637055 bytes 3 files with 634766 bytes Ready Queue Obytes Source files Source directory Destination files Destination directory Fig 27 FTP program FileZilla Open the source directory where the AppBase files are stored on the host computer Open the destination directory D Appl Copy all
9. OxFF This is the standard AEB message It indicates that the application is alive and that the AEB filters have detected no potential crash object AEB_WARNING Message ID CAN_base_ID 1 length 2 data 0x55 OxAA AEB has detected an object inside the driving path that is closer than the way to stop but there is still a chance of escaping to the left or right of the object This warning informs that a crash might happen soon Therefore measures should be taken that reduce the reaction time in the case of an actual crash e g the brake booster can be pretensioned This message is repeated as long as the potential crash object is detected AEB_ALARM Message ID CAN_base_ID 1 length 2 data OxAA 0x55 AEB has detected a crash object so that an emergency braking must be initiated This message may be sent without a prior AEB warning because of a sudden change in the traffic situation This message is repeated as long as the crash object is detected Note that if AEB is not active e g because the parameter read has failed or no vehicle data is available no messages will be sent In this case a warning will be given both in the dialog window of the AppBase and in the log file 7 3 2 Other applications As stated at the beginning of the previous section AEB is only one exemplary application for the ALASCA laserscanner Other applications are available from Ibeo too e Automatic Stop amp Go e PreCrash e Pedestrian P
10. The scan frequency is 12 5 Hz Scanner 0 notifies the SyncBox at t 112 ms that it is synchronised scanner does so at t 64 ms Ext_Sync_in must be kept high at all time to remain in timer mode Ext Sync_In Ext Sync Oul Jitter_ Warning_Out Synced_Out_0 Synced_Out_l RS232 TX 071 0 ms 80 ms 160 ms t The signal Ext_Sync_Out_Inv is the inverse of this signal Tf unconnected Ext_Sync_In is kept at high level by an internal pull up resistor 5 5 2 Timing example for bit I O mode The signal Ext_Sync_In is supplied by an external source After the first 1 ow to high transition the SyncBox activates the bit I O mode In the figure shown below the externally supplied scan frequency is 25 Hz derived from external input After a low to high transition is recognised the SyncBox sends the sync command via RS232 and sets the signal Ext_Sync_Out for 5 ms Ext oync ln Ext Sync Out Jitter_ Warning_Out Synced_Out_0 Synced_Out_1 RS232 TX 0 1 0 ms 40 ms 80 ms t The signal Ext_Sync_Out_Inv is the inverse of this signal Chapter 5 SyncBox 38 5 6 Setting timer or bit I O mode By default the SyncBox runs in timer mode after start up The operation mode changes automatically to bit I O mode when a transition is detected on the input Ext_Sync_In or Ext Syne In DDL 5 7 Interfaces and Pinouts The SyncBox uses a bit I O port and both serial interfaces All inputs have int
11. bit O mode e In timer mode the SyncBox itself generates the synchronisation frequency This signal is also available on a bit I O line to synchronise external sensors to the 0 direction of the scanners For instance a video camera can capture a video frame when the scanner s measure in the 0 direction e In bit I O mode the SyncBox gets the synchronisation frequency from an externally generated periodic signal that is received on a bit I O line This mode allows the synchronisation of the laserscanners to an external frequency For instance the capturing of camera frames can trigger the synchronisation Chapter 5 SyncBox 33 5 1 Synchronisation details The accuracy of synchronisation i e the temporal difference between the synchronisation pulse and the crossing of the 0 direction is about 200 us if no external forces act upon the laserscanner esp no angular acceleration This is equivalent to an angular accuracy of 0 9 or 1 8 around the true 0 direction for rotation frequencies of 12 5 or 25 Hz respectively The external synchronisation frequency fsyne may be selected from the range 10 Hz lt fsyne lt 40 Hz and should have a relative accuracy better than 0 1 the better fsync the better synchronisation Therefore it is not recommended to send the synchronisation signal from a PC because its timers are usually not that accurate Instead a dedicated microcontroller should be used to generate the synchronisati
12. 3 Ground detection ALASCA s multi layer technology allows for ground detection cf Fig 5 It is important for the application to distinguish between ground points and object points because ground must not be tracked as an object in automotive applications When scanning the ground the different incident angles of the scan planes result in a characteristic scan pattern that is detected by the ground detection module Scan points detected in this way are labelled internally as ground and are excluded from the object tracking 7 1 4 Scan data correction A scan is not an instantaneous snapshot of the sensor s surroundings but rather takes some time to be measured e g 25 ms for 180 scan area and 20 Hz scan frequency The task of the scan data correction is to shift scan points back to a common point in time This point is the time of the 0 measurement For this computation the ego motion is needed which is estimated by another module see chapter 7 1 6 After scan data correction the scan is an instantaneous snapshot Scan data correction becomes relevant if the sensor is moved or if the scan data of more than one laserscanner are merged scan data fusion to overlay or extend scan areas Note that vehicle data must be supplied to the laserscanner system in order for this module to work 7 1 5 Scan data fusion If more than one laserscanner is integrated in the vehicle the individual scans have to be merged to one big sc
13. 38 5 8 Elezitealcharset sal em N M N MD MNUNrFr H r HI MM MM 39 5 8 1 POWO S D r hr EE E 39 3 0 2 ISA TOZ NNN ea ten set Deraa 2a 39 5 9 Synchronisation without SyncBox scssi aaia 39 Se xyx w _ aa gt pDDED a rah o oreeeebebebbb bbrr 4 6 1 hJJ ep e e e ep p aabybkjbbldldcldlglrerrrrr rrr E 4 6 2 ISO 8855 coordinate system E eke keke kek kek ke Kek K K KK KK KA 4 6 3 Parameter Til Apo ase D sakal nen he nea re ee ee 41 6 3 1 So 12 015 E _ _ _ _ _ rrr r r J pprrrrrz r r 2o n o0 41 6 3 2 Section Parameter h keke k kk kK KAKA KA KK KAR 42 6 3 3 AS 2 61 N16 S S 01S 6 e n DY VD Dr en ne en Ree rene ne 44 6 3 4 el 9 RS N yyy _ aJ eee 44 6 3 5 SEHON N ec agg er ee re et 44 6 3 6 Sections Velocity and SteeringAngle Vehicle Data Parser 45 6 4 Mounting Pos ton esse Eke keke eke keke ke kek k keke KK KA KA KAKA AH HHH HAK RA 41 6 4 1 MAan dl d PCT MATION een 48 6 4 2 Automatic determination keke kk keke k k ek KAKA K A 49 6 4 3 Vertical Al Se nenne ee ee nee ee 49 6 5 More Sa a Teenies ee 50 SO Al ee 32 7 1 DC ACA ta PEC Process I Seesen ee 52 7 1 1 Dirt detection and range estimation kk kek se 52 7 1 2 FR AT Ce CUO VERNEUURBERSUEREENER EFRUEFEEREEEREUTNEFEEPETEEBERLENEUEEEPEBEREREESTHFEREPEUERENEELUEH
14. CAN message so that the vehicle computer can verify the state of the ALASCA system The state information comes along with the so called list end CAN message A complete reference of all Ibeo CAN messages can be found in the separate manual CAN message protocol 3 3 2 4 RS232 connection The RS232 connection at the ECU is used to synchronise ALASCAs and other sensors like a video camera A periodical signal is sent on the RS232 interface to control synchronisation Synchronised sensors look as good as possible straight ahead to the 0 direction each time the synchronisation signal is received For this purpose a fine tuning motor speed controller is integrated into the scanner Note ALASCA users with an IPC Industrial PC predecessor of the ECU have no direct access to RS232 when using standard connector cables In this case the only way to access RS232 is to modify the ALASCA connection cable and add a RS232 connector to the cable The pinout of the ALASCA connector is described in the table on page 11 Chapter 3 Handling and operating instructions 13 The RS232 connection must be set up using the following parameters 57 600 bits s ______ patabits 8 ____ _ _ Handshake Ibeo offers an optional hardware interface for synchronisation the so called SyncBox For details please refer to chapter 5 3 2 5 Ethernet connection The Ethernet interface connects the ECU to the local network or to a service laptop Due to t
15. OR CONSEQUENTIAL DAMAGES RESULTING FROM PERFORMANCE OR FAILURE TO PERFORM HEREUNDER OR THE FURNISHING PERFORMANCE OR USE OF ANY INFORMATION PRODUCTS OR SERVICES HERETO WHETHER DUE TO BREACH OF CONTRACT BREACH OF WARRANTY NEGLIGENCE STRICT LIABILITY OR OTHERWISE THE SYSTEM MUST NOT BE USED AS A LIFE SAVING DEVICE Safety notification Please read carefully Throughout this manual important specifications and hints for the safety of both the human operators bystanders and the system itself are given In order to highlight the most important topics these points are marked specially as shown below NEVER attempt to violate the rules or specifications given within this document especially at any of these signs as serious Consequences may arise from such behaviour This sign is the most important and critical warning throughout this document It marks warnings and descriptions which are critical for the safety of operators bystanders or the system This sign warns about an electrical risk that may be present in the system This risk may be a critical threat for the operators or the system itself This sign warns about a general risk or gives important information which must be obeyed to ensure the proper operation of the system Chapter 1 Introduction 1 1 Introduction This user manual introduces the ALASCA laserscanner Chapter 2 gives background information to make the reader familiar with the ALASCA technology It
16. absolute velocities can be determined 7 2 4 Street detection The street detection module tries to estimate the course of the street ahead It uses boundary objects and tries to find a clear path through these objects At this process vehicles on the street are ignored The module yields the vehicle s position on the street implying which lane the vehicle drives on the street width and curvature and the range of view available for street detection These parameters are included in the CAN output 7 3 Applications Application modules evaluate all available data scan object and vehicle data to solve their tasks In contrast to the object tracking the applications generate information that can be used directly for actions of the vehicle Applications AEB Crash prediction Pedestrian protection Fig 46 Overview over some applications AEB Automatic Emergency Braking Object tracking data 7 3 1 Automatic Emergency Braking Note This application is an optional module that may not be part of the delivered software package To order this module please contact Ibeo Moreover the documentation in this chapter has also an exemplary character to give a deeper insight in one concrete application Apart from AEB Ibeo offers many other applications Please visit the Ibeo homepage www ibeo as com to get informed about more applications The entire laserscanner system including Automatic Emergency Braking is
17. does the multi layer technology work In detail the photo diode receiver shown in Fig 3 is composed of a linear array of four independent receivers Each receiver corresponds to one layer also called channel Seen through the sensor s optical components each channel has its own field of view Fig 6 Since the photo diode receiver remains stationary while the mirror revolves the fields of view are rotated Fig 8 shows the rotated fields of view for some exemplary mirror directions a When a runs over a full revolution the midpoint of each field of view moves on a certain cosine like curve Fig 9 and Fig 10 U t echoA echo B echo C a O 5 2 ne gt detection threshold Un I re a a ak ek ak I T mm I ey eo O ta WA B WB Ic We I d 0 da dp dc Fig 4 Exemplary output voltage U t of the photo diode receiver The laser pulse was transmitted at t and afterwards reflected somewhere The threshold voltage U separates system noise from the relevant laser pulse echoes The velocity of light co relates time f and distance d 2d cot The echo pulse widths wa pc are also measured by the ALASCA The echo D is not shown here Fig 5 Laserscanners with only one scan plane are not suitable for automotive applications because tracked objects may get lost due to pitch movements as the upper figure illustrates ALASCA s multi layer technology allows for pitch angle compensation by
18. explains the measurement principle and introduces the visual interpretation of scan data Chapter 3 instructs the reader how to install handle and operate the sensor such that safety requirements e g eye safety will be met Chapter 4 concentrates on the electronic control unit coming along with the ALASCA Optional hardware components of ALASCA systems are described in chapter 5 Chapter 6 gives insight in the object tracking that the software in the electronic control unit performs based on the ALASCA s scan data Chapter 7 focuses even more on software It explains the software structure and gives concise descriptions of the individual software modules Finally chapter 8 shows the physical dimensions of the ALASCA Please note that this user manual cannot cover all aspects of individual configurations that are possible for different users If in doubt the reader is encouraged to directly ask for support at Ibeo Automobile Sensor GmbH short form Ibeo address see page Il Chapter 2 Laserscanner ALASCA 2 Laserscanner ALASCA The ALASCA Automotive LAserSCAnner is a multi layer laser based range finding device which measures the distances to objects in the surroundings of the sensor The created range profiles of the different scan planes are called a scan The user can configure the direction of the scan area as well as several other parameters The sensor is typically
19. new AppBase files via drag and drop to the destination directory click on the file hold left mouse button and move the mouse to the destination directory Another way is click with the right mouse button on the file and select upload Click on the OK button to overwrite the existing files Close the FIP connection and restart the ECU power up or click on the Start Application button in the program Servicelnterface exe Do not delete any files on the ECU 4 6 Maintenance The ECU does not require maintenance and has no user serviceable parts inside In case of failure please contact Ibeo Chapter 4 Electronic Control Unit ECU 27 4 7 Ethernet interface This document describes the Ethernet interface of the ECU which provides data transfer from the ECU to a host computer e g for data visualisation 4 7 1 Definitions The following data types are used to describe the Ethernet interface signed integers of 8 16 or 32 bit length respectively UINTS UINT16 unsigned integers of 8 16 or 32 bit length respectively UINT32 When sending multi byte data types i e data with a type other than INT8 or UINTS8 care must be taken of the correct byte order also known as Endianness because any data is sent as a byte stream on the Ethernet There are two different byte orders in common use called Little Endian e g Intel x86 compatible processors and Big Endian e g Motorola TCP IP network byte order They
20. of the sensor housing may get damaged Use a soft cloth with water and a non aggressive and non abrasive cleaner instead The sensor does not contain user serviceable parts inside Its housing is sealed watertight to protect it from environmental influences Do not open the sensor housing Do not use a jet cleaner or a steam jet cleaner to clean the sensor Do not clean the vehicle in a car wash when the sensor is mounted outside the vehicle not protected by an integration chamber 3 6 2 Cleaning optical parts This section applies only to special naked ALASCA sensors which are not mounted inside an integration chamber and have no protecting glass cylinder In this case optical parts of the sensor may become dirty for instance by remains of dust or fingerprints The optical parts to clean are e the deflection mirror and e the circular pane below the mirror These optical parts should be cleaned regularly using an optical cleaning kit that contains cleaning solvent and paper cloth suitable for optical instruments Such cleaning kits are available in optical supply and photo stores Please carry out the following steps for cleaning e Turn off the sensor Disconnect it from power to prevent the mirror from spinning e Remove grains of sand or other abrasive particles by blowing them away Do not rub them over the surface as this may scratch it and reduce the performance of the sensor e Take a fresh cloth sprinkle it wi
21. the Serial connector The ECU s ARCnet controller sends and receives data on the ARC out lines pins 1 and 9 The ARC in lines pins 2 and 10 are used for termination of the bus only If an external termination closer to the sensor s is used the ARCnet bus must not be fed back into the ARC in lines Serial connector pinout of the ECU 1 RS1RxD RxD signal of ALASCA 1 This pin is internally connected to pin 5 of connector ALASCA 1 Note that signal ground is RS_GND 2 RS1TxD TxD signal of ALASCA 1 This pin is internally connected to pin 12 of connector ALASCA 1 Note that signal ground is RS_GND 4 RS2 RxD RxD signal of ALASCA 2 This pin is internally connected to pin 5 of connector ALASCA 2 Note that signal ground is RS_GND 5 RS2 TxD TxD signal of ALASCA 2 This pin is internally connected to pin 12 of connector ALASCA 2 Note that signal ground is RS_GND 6 GND____ GNDofECUCOMI _ _ Receive line of ECU COM1 8 TxD Transmit line of ECU COMI internally connected to vehicle ground internally connected to vehicle ground CAN connector pinout of the ECU CAN_L CAN bus low Signal ground for all signals CAN_H CAN bus high LAN connector of the ECU The LAN connector is a standard 10 100 BaseTX Ethernet connector The matching plug is a BULGIN PX0834 B type available from Farnell InOne Order No 428 5864 Bulgin also offers read to use Ethernet cables Chapter 4 Electronic Cont
22. the x axis O direction This coincides with the ALASCA s 0 direction Since ALASCA s mirror rotates clockwise the start angle of the scan is usually greater than the end angle As an example in Fig 35 a 160 scan area is drawn in red colour starting at 80 and ending at 80 If start and end angles were swapped this yielded the comple mentary scan area crossing the 180 boundary The maximum usable scan area is limited to about 240 6 3 Parameter file AppBase ini The ECU will start the sensor automatically after booting Before the first scan the AppBase software restores the last saved parameter set from the ECU After that the sensor will send object data via CAN for every scan A number of parameters control the steps of the object tracking process The parameters are stored in the file D Appl AppBase ini short ini file on the ECU s built in CompactFlash card The file can be edited with a text editor Note Changing any parameters with the CAN interface has only a temporary effect until the power is switched off In order to save the parameters so that they are restored after every power on use the Store Parameters to Flash command Note Never change unknown entries in the ini file 6 3 1 Syntax The AppBase ini file is separated into sections where each section groups a number of parameters A section begins with a line that contains the section name in brackets e g Vehicle
23. tilt angle of the optical window Fig 19 must measure a minimum of 22 at that point where the laser beam hits the window perpendicularly see Fig 21 beam 1 For design reasons it is possible to steadily reduce the vertical tilt angle from 22 at perpendicular horizontal incidence down to 0 on each end of the window ALASCA Reflections 2 gt Fig 21 top Position of the integration chamber in the vehicle Right Top view on a front left integration chamber Two laser beams at scan angles 45 beam 1 and 30 beam 2 are depicted Beam 3 5 Damage to the laserscanner If the laserscanner becomes damaged it is necessary to stop working with the system immediately In this case disconnect the laserscanner from power to avoid further damage to the system Please send the laserscanner back to Ibeo to have your ALASCA repaired address see page II Chapter 3 Handling and operating instructions 18 The customer must not open the ALASCA Only use the laser scanner as directed Otherwise the laserscanner may cause harm due to high voltage or invisible laser radiation 3 6 Maintenance In general the ALASCA does not require maintenance However the items listed in the following subsections should be checked regularly 3 6 1 Cleaning the sensor Although the sensor s protected against water t must not be cleaned using a jet or steam jet cleaner as water may penetrate the seals or parts
24. 1 5 react Xbrake Xo It must hold Fig 47 Screenshot of the AEB application integrated in ASD In this example a crash object is detected and AEB has calcu lated that the crash is unavoid able by braking or steering so AEB is activated Vehicle outline green velocity approx 35 km h Blind range due to the system delay time red Way to stop blue Crash object red outline The object has tracking no 2 Its velocity equals 0 7 km h Driving path dashed lines Circular curve with the left escape radius NR Number of an object YA Absolute velocity km h Circular curve with the right escape radius Chapter 7 Software 58 100 lt nEscapeWayOffset lt 100 The default value is 25 xo is the offset between the front of the car and the origin of the vehicle s coordinate system It can be set with the parameter dDistOriginFront m cf Fig 42 default 0 6 m v is the vehicle s current velocity tT is the system dead time which is the sum of the parameter uSystemDelayTime from the previous step and the parameter uSystemPreFiredTime ms The latter one is the time between triggering an AEB alarm and the beginning of deceleration default 300 ms must not be greater than 10 000 ms d max 15 the maximum longitudinal acceleration when fully braking ax max is set by the parameter dMaxAcceleration m s and must be a negative value i e deceleration The defau
25. NEEESERREER 53 7 1 3 HOUT CCL CO ee ee E ena KARA ER Ge GOR N 53 7 1 4 S CAD dal Orte On energie 53 7 1 5 SCALA N a 1 ee _ r een ee een 53 7 1 6 Epo monon sc N e nein een 54 7 2 ODIECE WE T ee ee ee nern 54 T 21 SE O 1 WOSTERRUREERORNEEEUEINGREESEPENELLTURLUNEEEEEUNNIEUEULGREEEHENNLLTURLUNENEREENNEETEELUREE RECHNEN 54 1 02 OTM UE Mac KIN nee ee ern 54 7 2 3 erik OT ee 54 7 2 4 SIE LI LO ne ne occa ace ole nna r eee TT 55 7 3 POTD CAN ONS Dw ww wwm eanmmwpreggmno 22 7 3 1 Automatic Emergency Braking keke keke kek k 55 7 3 2 s ball a ee E en ee see 59 Physical dimensions sense ea ll ll eee mi lgce 60 8 1 ALASO nee rennen ee 60 8 2 Standard ntesration chamber aan 61 8 2 1 BIOS Se ea ne nenne 61 8 2 2 Mounl nashor DOldOf assessed 62 8 3 P U E E era as res ue 63 8 4 SYDEDOX ee ee ee E A ee 64 Re en en ee nnn 65 DISCLAIMER PLEASE READ CAREFULLY THE SYSTEM AND ALL COMPONENTS INCLUDING SOFTWARE AND THIS DESCRIPTION HAVE BEEN MANUFACTURED WITH GREAT CARE TO ENSURE ITS PROPER FUNCTION HOWEVER THE SYSTEM AND OTHER HARD AND SOFTWARE DESCRIBED IN THIS MANUAL IS CURRENTLY IN PROTOTYPE STADIUM ALL OF THE COMPONENTS DESCRIBED HEREIN MUST BE USED IN A WAY ENSURING THAT NO HARM MAY COME TO HUMAN OPERATORS AND BYSTANDERS IN NO EVENT REGARDLESS OF CAUSE WILL IBEO AUTOMOBILE SENSOR GMBH ASSUME RESPONSIBILITY FOR OR BE LIABLE FOR INDEMNIFICATION OF THE OTHER PARTY OR FOR INDIRECT SPECIAL INCIDENTAL
26. OK Normal scan point 1 PT_STATUS_INVALID Do not use this scan point Note that invalid scan points are not transmitted therefore this status should never be received 2 PT_STATUS_RAIN For echoes from rain drops 3 PT_STATUS_GROUND For echoes from the ground 4 PT_STATUS_DIRT For echoes from dirt on the pane of the integration chamber Note 8 Distances are encoded such that values up to 100 m have a resolution of 1 cm and values above 100 m have a resolution of 10 cm The conversion between an INT16 value n and the corresponding distance d in metres 1s as follows nx0 lm 900m if n lt 10 000 d nx0 01m if 10 000 lt n lt 10 000 nx0 I m 900m if n gt 10 000 Chapter 4 Electronic Control Unit ECU 31 10 d 900 m m if d lt 100m n 100 d m if 100m lt d lt 100m 10 d 900m m if d gt 100m For INT16 values the ranges of n and d are 32 768 lt n lt 32 767 2 376 8 m lt d lt 2 376 7 m Note that it is not recommended to use the z component of a scan point it is only transmitted for completeness Practically the z component is problematic because it refers to the local coordinate system of the respective scanner even in case of a fusion system Since the pitch angle of the laserscanner is not known a conversion to the vehicle s ISO 8855 coordinate system is impossible Nevertheless the z components of all points that originate from the same scanner can be compared relatively Note 9 Currently an
27. PreFiredTime 300 dMaxAcceleration 10 0 dMaxCrossAcceleration 5 0 dTurningCircle 11 0 gt Ir Two requirements must be met for the AEB application to work 1 The ANB section of the AppBase ini file must contain valid settings i e name spelling must be correct and values must be plausible If parsing of the ANB section fails a warning will appear in the AppBase dialog window and in the log file and the AEB application is aborted Care must be taken that all parameters are set correctly since there is no error message in case of missing or redefined parameters Missing parameters will be set to their default values without notice Vehicle data must be sent regularly at least once a second Otherwise an error message appears in the AppBase dialog window and AEB will not work It is recommended to Chapter 7 Software 59 update the vehicle data at 10 Hz Higher update rates do not improve the quality but may cause unwanted delay because all incoming messages must be evaluated If any object passes all AEB filters a collision with this object is unavoidable and the AEB application initiates an emergency braking by sending a CAN message After the application is started successfully AEB sends CAN messages periodically with the scan frequency All messages have the ID CAN_base_ID 1 and are two bytes long The following messages are available AEB_ALL_CLEAR Message ID CAN_base_ID 1 length 2 data 0x00
28. TS AMAT ONO UEC A Pierre ee ee see 18 Bleeronie Cone ol Unit CH CO N NnRnE EnnNnEnEEnEnEnRmnnRnn nEnEanEnNE uEHNHE NnNnE NE EE MHIMnM eier 20 4 1 DVO CE IVs NGC Uee E AEA EEA 20 4 2 Oreja Tay en Ve ee ee a ettnenT arr r xm 21 4 2 1 dua AG ee ee ee ee om 21 4 2 2 PCAC COMMS CIO DI OWS ee ae er ee ae vedo En bewey b VE 22 4 3 MET OT AS eh 24 4 4 SUE I A S lel Innere ee ee 24 4 5 OME Vy AU TS AUS nee ren coe nome 22 a 24 469 DD ee an 26 4 7 Ein PCE TANG GLACE teasacanecacesuasasucsseacsces cu R E A EE 27 4 7 1 MEST e NONE panes cececnescea casas seeeeetdpereicetcceascoa eenasaeaeeecta neees ce aeeacea e 21 4 1 2 Data Transfer ee esse 21 4 1 3 hevsal nda a CC 7 11 DRSERUEFUNNNENGEL E ER IEEREONGEUE RER TEERTENERUSPERCER 28 4 7 4 MVE COINS Scan di nen een era enen 28 SYD BORN een 2 5 1 EPALE Na Sol S a wwAARARrrryy eeeee JeJ 33 32 San Sen n yal In Wer MG eier 33 5 3 System layout in bit YO moOde keke kek keke kek k K K KA 33 5 4 Sy CB Ox LEDs and COMIC C OLS een ee ee 35 55 Signals of the SyncBox TTL and LE kek keke k k 36 5 5 1 Timing example for timer moOde een 27 92 2 Timing example for bit I O mode keke keke 37 5 6 Settna umer or DiL TO TMOG nenne ee G n Wa kda 38 5 7 Taterlaces And P mals ea ee ae ee PP 38 5 7 1 POW Er SUD iy ind DIL QO euren kerek la seke cua keke nn ne bu kaya dak b n 38 O 9 5 1 2 ESS W N N N N N NNN er rrr zz
29. able that disturb the signals The ARCnet bus system is internally not terminated to allow connecting multiple sensors to a single bus but it must be terminated at both ends of the bus see Fig 15 The standard ALASCA ECU connector cable delivered by Ibeo is correctly terminated ARCnet ARCnet termination CAN termination Fig 15 ARCnet and CAN termination for a standard ALASCA system The following table shows the pinout of ALASCA s 15 pin connector 6 Power supply 12 VDC __ Power supply 12 V DC 9 ARCnet in ARCnet out Note Do not connect the unused pins RS232 TX transmit that are not listed in this table Power ground Signal GND Power ground Signal GND For self made connector cables please take care of the following ARCnet items e The ARCnet bus is not terminated in the ALASCA sensor Instead the end of the ARCnet cable must be terminated e Signal cables should be as short as possible to avoid distortions Do not exceed the maximum cable lengths specified by the interface standard e Never create cable stubs T branches Chapter 3 Handling and operating instructions 1 e ARCnet transmission runs at 10 MBit s Data transmission will become unstable and produce strange errors if low quality cables are used Ibeo recommends high quality twisted pair cables with 120 Q characteristic impedance The pins ARCnet in and out should be connected to one
30. an before the object tracking can take place This procedure is called scan data fusion Since the scanner positions must be known for the merging of the scan data the mounting position detection procedure must be done for the system see chapter 6 4 Chapter 7 Software 54 7 1 6 Ego motion estimation Ego motion is the motion of the vehicle where the laserscanner is mounted The ego motion is estimated based on the data from the vehicle velocity steering angle combined with a mathematical model of the vehicle s motion The result of the ego motion estimation is used by the scan data correction chapter 7 1 4 and the computation of absolute velocities for objects tracked in the scan 7 2 Object tracking The object tracking modules implement a high level abstraction from the scan data They perform the transition from scan data many individual measurements to object data condensed and interpreted information Objects are structures in the scan data that have been recognised algorithmically as an independent entity For each object the geometric dynamic and qualitative properties are computed e g position velocity contour and classification Object tracking Scan data pre scan _ Segmen Contour Classifi Street processing tation tracking cation detection Fig 45 Simplified overview over the object tracking For clarity some internal modules have been omitted 7 2 1 Segmentation The segmentation procedure forms g
31. atio0 16 155 exemplary data SteerRatiol 4 241E 04 SteerRatio2 2 178E 05 SteerRatio3 2 516E 09 Coefficients of the transmission ratio polynomial Type 1 Transfer function Let x be the steering wheel angle in degrees The front wheel angle is directly calculated by FrontWheelAngle SteerRatio3 x SteerRatio2 x SteerRatiol x SteerRatio0 SteerRatioType 1 The following coefficients belong to a transfer function polynomial SteerRatio0 0 0 exemplary data SteerRatiol 5 383561 E 2 SteerRatio2 5 704158E 6 SteerRatio3 1 199232E 7 Coefficients of the transfer function polynomial 6 3 6 Sections Velocity and SteeringAngle Vehicle Data Parser A few modules of the application software AppBase need information about the vehicle like velocity steering angle and so on If these parameters are not available the modules will be disabled automatically To be able to support CAN protocols of different vehicles AppBase has an integrated vehicle data parser The parameters of the vehicle data parser are specified in the sections Velocity and SteeringAngle Both sections need the same set of parameters as listed below There are no default values for these parameters Identifier The identifier of the CAN message that contains the vehicle parameter e g the velocity Valid values are decimal or hexadecimal numbers like 648 or 0x288 FirstBit LastBit The range of
32. better visualization only Axes annotation is given in metres 5 ACC The ACC criterion generates the object output list according the requirements of an ACC application This criterion filters all uninteresting objects for this appli cation In difference other criterions only determine the output order by a quality and send as many objects as possible even if they have a very low priority The necessary conditions for an object to be sent are e The object is tracked longer than 0 5 s e The object must have the same main moving direction as the own vehicle e A small object must be closer than 10 m Small means that the result of the object classification is unknown small e The object must be on my lane or on the lane right or left of it e The object output order is similar to look ahead SendObjects 20 Maximum number of objects that may be sent for each scan 0 31 x OutputAreaX1 0 0 x y OutputAreaY1 0 0 OutputAreaX2 0 0 OutputAreaY2 0 0 As Fig 37 shows the points x y1 and x gt y2 define a trapezoidal area the so called output area If these points are specified only objects inside the output area are sent in the CAN or Ethernet output An object is inside the output area if any scan point of the object is inside the output area If X1 y1 xo 2 Y Fig 37 The four parameters x y1 xo all values are zero or not specified the output and y gt define a trap
33. bits where the parameter value is located in the CAN message The first bit corresponds to the least significant bit LSB and the last bit to the most significant bit MSB of the value A CAN message has 8 bytes with 8 bits each thus FirstBit and LastBit must lie within the range from 0 to 63 see examples below SignBitAvailable For some parameters there is a sign bit placed in the CAN message that determines if the current value is negative or positive If a sign bit is available set SignBitA vailable TRUE otherwise set to FALSE SignBit If a sign bit is available this value defines the position of the sign bit in the CAN message e g SignBit 15 If the sign bit is set the value is considered as being negative ErrorValue For some parameters an error value is defined If the parameter is equal to the given ErrorValue this parameter is invalidated and will not be used for internal calculations If there is no error value defined ErrorValue should be set to a value out of the range e g OXFFFF Factor Offset Parameter values must be decoded by a simple linear equation decoded value encoded value x Factor Offset Chapter 6 Object tracking 46 The encoded value is the integer value extracted from the bits between FirstBit and LastBit and the optional SignBit The units of Factor and Offset must be metric e g velocities in m s or angles in radians These are the internal units Note that at the user interface of ASD o
34. connected to an ECU Electronic Control Unit which runs the object detection tracking and classification algorithm This algorithm converts the scan into a set of objects and tracks and classifies these objects Objects have properties like size position velocity type etc They are sent from the ECU to the host computer on a CAN bus or an Ethernet interface 2 1 Terminology Fig 1 visually explains the terms that are used in conjunction with the ALASCA throughout this document Protecting glass cylinder optional Head Rotating mirror Fastening __ i Housing Fig 1 ALASCA components The protecting glass cylinder is installed only at stand alone ALASCA sensors in place of an integration chamber 2 2 Principle of measurement The ALASCA laserscanner is a measuring instrument based on LIDAR technology Light Detection And Ranging It scans the surroundings by means of a rotating infrared laser beam The built in laser transmits short rapid fire pulses that are reflected by objects in the surround ings Fig 2 The laserscanner can detect the reflections which allows for a measurement of the pulses times of flight From these times and the velocity of light the distances to the objects can be determined In parallel the direction to each object is known from the angular position of the rotating mirror that deflects the laser beam Fig 3 shows the main components inside the ALASCA that are involved in the measurem
35. currently in prototype stadium For safety reasons never S use this application in closed loop on public roads Chapter 7 Software 56 The Automatic Emergency Braking application AEB is designed to reduce the threat due to frontal collisions When AEB detects a possible crash situation brakes are pretensioned auto matically as a precaution to shorten the response time of the brakes The AEB system will maximise the brake pressure if a collision cannot be avoided anymore AEB aims at mitigation of the accident consequences by reducing the velocity at the time of collision The collision will explicitly not be avoided even though this would be possible to some extent with the current system The reason for this approach is given by the driver as a human being When an automatic emergency braking happens the driver is overridden by an electronic system It cannot be assumed that a driver instantaneously can continue driving after a collision has been avoided automatically Consequently the decelerated vehicle would move in the traffic as it was driverless or after coming to standstill would be a potential obstacle for the following traffic These considerations give rise to legal questions concerning product liability In daily routine the driver will not notice the AEB system because normally AEB is only monitoring the surroundings for dangerous situations As long as the traffic situation is fine the AEB system is in the all clea
36. differ only by the direction of reading The following table shows the byte streams for similar sample data that have a length of four bytes each 0x denotes hexadecimal numbers Standard PCs with Intel compatible x86 processors use Little Endian whereas Big Endian is the recommended byte order for data exchange on the network If your processor architecture is of type Little Endian data must be converted between Little and Big Endian Users of a Microsoft Windows operating system can do this e g using the C functions htons htonl ntohs and ntohl that are declared in the Microsoft header file winsock2 h 4 7 2 Data Transfer The Ethernet interface uses the TCP IP protocol and port number 12 000 for communication Data is sent automatically when connecting to the port All data that is sent to or received from an Ibeo application has the same general structure a 16 bytes message header followed by the message body itself Chapter 4 Electronic Control Unit ECU 28 Message header 4 x UINT32 always Big Endian 1 Magic word always UINT32 Ox AFFECOCO Note 0 zero not letter O 2 Size of message body in bytes UINT32 3 Data type of message body see constants FILE_TYPE_ in the header file ASL h UINT32 4 Time stamp in milliseconds when the message was sent UINT32 Message body The byte order is always Big Endian Different data types e g scan data object data
37. e a dirt detection module is included This software module defines dirt as fixed scan data close to the sensor up to 1 2 m It recognises such fixed data and marks the sensor as being dirty In this case all scan points up to 1 2 m are excluded from the object tracking and the sensor dirty flag in the Environ mentInfo CAN message is set Chapter 7 Software 5 To verify this module the scan area can be partially covered by hand directly in front of the sensor After five seconds until scan data is recognised as being fixed the dirt detection module signals a dirty laserscanner Some seconds after removing the hand the module signals a clean state again The dirt detection module also estimates the current range of view by averaging the farthest scan points of the most recent scans This range estimation is printed as view range at the bottom of the AppBase window 7 1 2 Rain detection Rain may produce randomly scattered isolated scan points like noise in the near field in front of the sensor up to about 10 m This range depends on the size of the rain drops and the intensity of the rain The rain detection module internally labels such scan points as rain These points will be excluded from object tracking The module also estimates a measure for the rain s intensity This measure is defined as the number of rainy scan points out of 1000 scan points The intensity comes along with the EnvironmentInfo CAN message 7 1
38. e points of a scan e g 50 ms at 10 Hz and 180 scan range This recording time results in a distortion of objects that move relatively to the laserscanner To reduce this effect all scan data are compensated for the absolute velocity of the vehicle so called scan data correction After that step all scan points are corrected to the positions they nearly had at the reference time stamp and the scan data has become an instantaneous snap shot of the surroundings The restriction nearly refers to the fact that the scan data is not compensated for the absolute velocity of the moving objects in the surroundings which also contributes to object distortions Note 4 Angles are specified according to the ISO 8855 coordinate system see section 6 2 with the unit radians x 10 The conversion between an INT16 value n and angle a in radians is a n 10000 31416 lt n lt 31416 10 0004 7 lt lt 75 n where means rounding towards the nearest integer Please note that the extreme values n 31 416 slightly exceed the z boundary The angular resolution arising from this conversion 1s approximately 1 175 0 0057 10 4 rad Note 5 Channel numbers 3 channel 4 yellow top 2 channel 3 green 1 channel 2 blue 0 channel 1 red bottom Note 6 Sub channels 0 sub channel A first echo 1 sub channel B second echo Note 7 The point status can be one of the following values 0 PT_STATUS_
39. e syn chronisation of the laserscanner s see section 5 e LAN 10 100 BaseTX Ethernet interface This high speed interface offers access to all data from the ECU as well as control of the ECU software Software updates can be downloaded via the LAN port see section 4 5 Do not open the housing of the ECU unless being explicitly instructed to do so Opening the housing may break its watertight seal Before touching any components take measures against electrostatic dis charge as this might destroy the ECU 4 2 2 ECU connector pinouts Power connector pinout of the ECU Positive power input may be directly con nected to vehicle power 12 V only The matching connector is a Lumberg Type 033203 plug It is available from Farnell InOne www farnell com order no 329 6611 ALASCA connector pinout of the ECU Signal ground for all signals SV ext For active ARCnet termination max 400 mA via jumper default off 4 6 J 2v ____ Power supply 12 VDC ________ 8 Shield ______ Connect to cable shield _____________ 9 JARC out __ ARCnet out ARCnet in The signal names of the RS232 signals are identical to the ALASCA signal names and thus the signal direction is stated from the sensor s point of view For instance Chapter 4 Electronic Control Unit ECU 23 RxD on the ECU s ALASCA 1 connector is the receive line of the sensor and must be connected to an external TxD signal on
40. echo pulse width is given only as an integer value with an arbitrary unit A small value corresponds to a small echo pulse and vice versa For future sensor generations a conversion e g to nanoseconds temporal pulse length and or metres spatial pulse length may be available Fig 29 The SyncBox 5 SyncBox Note The SyncBox is an optional system component that may not be part of the ALASCA system delivered by Ibeo The SyncBox Fig 29 is a hardware interface to synchronise laserscanners with other external devices e g a camera Synchronisation minimises time shifts in the data collection of the connected laserscanners This is especially useful for scan data fusion where synchronisation reduces the need for scan data corrections during processing Thus the induced error is also minimised resulting in an improved performance and reliability During the synchronisation process the laserscanners adapt their scan frequency to a given synchronisation frequency in such a way that each scanner measures at its 0 direction at the time of the synchronisation pulse Note that in a fusion system with two laserscanners only the SyncBox is not necessary for synchronisation because both laserscanners can synchronise directly master slave mode see section 5 9 The SyncBox allows the synchronisation of up to two Ibeo laserscanners Depending on the generation of the synchronisation frequency the SyncBox operates either in timer mode or in
41. eflection mirror is optimised for rotation frequencies of 12 5 and 25 Hz though it also supports any other frequency in the range from 8 to 40 Hz This frequency is directly related to the available angular resolution as shown in the following table The relation arises from considerations to ensure eye safety and to protect the laser from overheating 8 0 Hz lt f lt 12 5 Hz gt 0 25 continuous 0 125 short term 12 5 Hz lt S lt 25 0 Hz gt 0 50 continuous 0 250 short term 25 0 Hz lt f lt 40 0 Hz gt 1 00 continuous 0 500 short term Chapter 2 Laserscanner ALASCA 7 The restriction short term in the table means that the high angular resolution is available only for a sequence of a few laser shots In automotive applications this sequence is typically located in driving direction to have a high resolution scan of the oncoming objects In automotive applications there are some directions e g ahead more relevant than others e g lateral An application can put its focus on the relevant part s of the surroundings by using high resolution scan data there and low resolution data in the less relevant parts The ALASCA XT supports flexible angular resolution to meet this requirement Fig 11 The default setting of the flexible angular resolution puts focus especially on a range of 16 around the driving direction which is defined as the x axis in automotive applications Here the short term high resolut
42. en the lines labelled with and e Like the human eye a laserscanner neither looks through infrared opaque objects nor looks round the corner Therefore cars trucks and busses generally appear L shaped in the scan because a single sensor can see at most two edges of a vehicle s outline at the same time e The colours of the scan points refer to ALASCA s multi target and multi layer capabili ties see chapter 2 2 IBEO AS ASD Birdview lolx Properties Grid Info avai au amp Ve og a 829 Log oe oo aa Position of camera Left margin of video window Right margin of video window Position of ALASCA Scan start angle Scan end angle Colour legend for scan points 4m Om 4m 8m 12m Fig 12 Relation between the scan view left window bird s eye view and the corresponding video view right window The video view shows only a small part of the wider scan view the angular range is 35 8 out of 160 Pink annotations are overlaid for clarity they are not part of the views Chapter 3 Handling and operating instructions 9 3 Handling and operating instructions The ALASCA is a highly sensitive optoelectronic device Although it is designed for auto motive applications the device should be handled with care to avoid damages Moreover the built in laser may cause harm due to invisible laser radiation if it is not handled as directed This chapt
43. ent 2 2 1 Multi target capability When a reflected pulse reaches the photo diode receiver the received intensity 1s converted to a voltage The reflection will be detected if its voltage exceeds a given threshold This thresh old prevents system noise from being detected as false objects a Transmit laser pulse red dot b Reflect laser pulse c Receive laser pulse d Time of flight t distance of flight 2d cot Fig 2 Principle of time of flight measurements The distance d to an object can be determined from the laser pulse s time of flight f and the velocity of light co Motor with angle encoder Rotating mirror Reflected echo Photo diode receiver IR transmitting laser diode Fig 3 Insight in ALASCA s internals Chapter 2 Laserscanner ALASCA 4 ALASCA s receiver electronics can detect up to four echoes per transmitted laser pulse e g echo A coming from the pane of the ALASCA s integration chamber echo B from a rain drop in front of the laserscanner echo C coming from an object farther away and echo D missing because of an opaque object at echo C This feature is called multi target capability Fig 4 It becomes mandatory if the ALASCA is integrated into a vehicle 2 2 2 Multi layer technology The ALASCA supports four scan planes with different vertical angles This so called multi layer technology is mandatory for automotive applications as Fig 5 illustrates How
44. entifiers are used e CANBaselID n for application messages e CANBaselD for commands to the AppBase e CANBaselD 1 for object data MinDist 0 5 Minimum distance between two segments of scan points If two segments lie closer together than this value they are merged to a single segment MinDist must be greater than 0 1 typical values are between 0 2 and 1 0 m Increasing this value to greater values e g 1m causes the segmentation and thereby the object tracking to become more coarse meaning that objects become merged and are tracked together Reducing this parameter to small values e g 0 2 m allows a much finer segmentation but causes objects to fall apart if there are small gaps in the outline This parameter is only valid in y direction The minimum distance in x direction 1s determined by the XY Factor see below XY Factor 3 0 Stretch factor for the segmentation in x direction must be greater than 1 In x direction the minimum distance between segments results from the product MinDist x XYFactor Because the main direction of movement is forward it is advisable in most situations to allow the segmentation to become coarser in forward direction This pre vents objects to fall apart in longitudinal direction Typical values are between 1 and 5 ObjectPoints 0 Number of points on the object outline Valid values are between 3 and 16 0 adaptively select the number of object points max 16 QualityCriterion 0 After the
45. er gives instructions how to handle the sensor and how to operate it in an eye safe way 3 1 Eye safety The ALASCA complies with the laser class 1 requirements of the European laser standard EN 60825 1 1994 A11 1996 A2 2001 see 1 The laserscanner is equipped with a scanning safeguard that shuts down the laser emission in case of failure of the scanning mechanism Do only use the laserscanner as directed Do not open the housing of the sensor and do not dismount the head of the sensor because then the laserscanner will no longer be eye safe and may cause harm due to invisible laser radiation 3 2 Connecting the ALASCA The ALASCA has one connector that includes both the power supply and the signal inter faces Fig 13 shows how to connect the ALASCA to the other system components The individual connections are described in the following subsections The ECU Electronic Control Unit is explained in chapter 4 external F RS232 __ synchronisation N a 7 lt xxx nan c R2 CAN PC laptop e Or vehicle Bihernet computer ECU ALASCA power supply 12 V DC Fig 13 Connecting the ALASCA system dashed lines optional components Chapter 3 Handling and operating instructions 10 i CAN E j object data vehicle computer Dn QO l Ethernet ARCnet object scan data optional service computer Fig 14 Types of data busses in the ALASCA system and the corresp
46. ernal 20 kQ pull ups to 5 V Therefore it is not necessary to make any connection in order to achieve a high level Signals that should have a low level can be connected to GND directly Do not connect pins that are not expressly linked to a function see tables below as this will interfere with the SyncBox 5 7 1 Power supply and bit I O has signalled that it is synchronised alice nn signal is too age is too large 6 Ext_Sync_Out_Inv Sync signal output active low 0000000000000 signal output active low Power In Positive power input The supplied voltage must be in the range of 9 to 18 V Short time transitions are also tolerable This input can be directly connected to vehicle power Ground pin corresponding to Power In It is also the GND reference for all output signals has signalled that it is synchronised Input for external sync signal 5 7 2 RS232 0 1 Transmit data SyncBox sends commands on this line Connect this line to RxD of the laserscanner Receive data SyncBox receives laserscanner replies on this line Connect this line to TxD of the laserscanner Reference ground Chapter 5 SyncBox 39 5 8 Electrical characteristics Do not reverse polarity on the input voltage Do not exceed the voltage limit 5 8 1 Power supply The SyncBox requires a 12 V 9 18 V 300 mA 3 6 W power input This input is filtered internally so that a direct connection to vehicle power is p
47. erscanner Chapter 6 Object tracking 50 A laser detector B target e Z e H 10m Fig 41 Vertical alignment of the ALASCA using a laser detector method A or a simple reference target method B The red shaded area has a vertical divergence of 3 2 The area is split up vertically into four channels of 0 8 divergence each cf Fig 6 Method A using a laser detector available from Ibeo While the ALASCA actively measures use the detector to measure the height above ground of the beam centre in a distance of 10 m in front of the sensor O direction Adjust the laserscanner so that the height of the beam centre is the same as the height ho directly at the laserscanner Repeat the previous step for at least one different direction e g 45 or 90 to correct a possible roll angle of the sensor After this correction the scan plane should be parallel to the ground level and the mirror centre should lie inside the scan plane Method B using ASD and a reference target Construct a simple target of height ho e g a wooden log or board with a foot to stand alone Put the target in a distance of 10 m in front of the sensor 0 direction Adjust the laserscanner so that in the ASD visualisation only the lower two beams default colours red and blue hit the target whereas the upper two beams green and yellow hit the background or show no measurement at all Note that there is no sharp border or a gap be
48. et until the scan data visualisation shows the wall exactly parallel to the x axis of ASD ASD ECU mode v3 1 7 Saks Live Tracking Parameter Vehicle Data Road Detection Parameter Scanner ID 24 Load parameters Horizontal angle offset Fig 39 The Parameter property Vertical angle offset zave parameters page in ASD is used to set the mounting position of the laserscanner manually Scan Freg 50 Hz Time Stamp 47356133 ms Scandata Buffer overflow occured 151248 mes Chapter 6 Object tracking 6 4 2 Automatic determination Ibeo delivers a software tool called ASystem Setup to detect the mounting position auto matically Note that the automatic mounting position detection requires time consuming preparation so that you might prefer to set the mounting position manually as described in the previous section The manual determination is usually faster than and as precise as the auto matic determination Even in ASystemSetup there is an option to enter the offset Ax Ay manually because in many cases this offset is known with high precision e g from CAD data ASystemSetup can use this knowledge to determine the horizontal angle offset Aa more precisely Fig 40 shows the calibration field that ASystemSetup expects The tip of the V shaped reference target red must be located exactly at the point Prep 10m Om in vehicle co ordinates Note that in contrast to Fig 38 the
49. ezoidal output area area filter is disabled RotationFreg 20 Scan frequency of all connected scanners 8 40 Chapter 6 Object tracking AA 6 3 3 Section Sensor_n Each sensor that is connected to the ECU must be configured by setting its scan start and end angle as well as the mounting position offsets The section name for the first sensor is Sensor_0 for the second sensor Sensor_1 and so on StartAngle 90 0 EndAngle 90 0 Start and end angle of the scan area see Fig 35 The maximum usable scan area is currently limited to about 240 to allow sufficient time for the ARCnet transmission of the scan data OffsetX 0 0 Offset Y 0 0 HorizontalAngleOffset 0 0 Mounting position offsets see section 6 4 SyncMaster FALSE In a fusion system with two laserscanners this flag distinguishes between the synchronisation master TRUE and slave FALSE see section 5 9 6 3 4 Section RS232 The RS232 port can be used to transmit status and error messages in plain text Each message comes along with the current time stamp The RS232 protocol used is 8N1 8 bit no protocol 1 stop bit This section is optional but if used all four entries must exist SendStatus FALSE Turns the RS232 output on TRUE or off FALSE SendANB FALSE Turns the AEB output on TRUE or off FALSE The AEB messages are for debugging purposes only Do not activate this feature AEB is described i
50. figuration some of the following modules may be disabled or unavailable This especially applies to the high level modules or applications 7 1 Scan data pre processing During scan data pre processing the scan data sent from ALASCA is filtered and corrected in many ways For example each individual measurement is checked for being dirt rain or ground Coordinates have to be corrected according to the mounting position parameters and sO on The following subsections give concise descriptions of the software modules that are part of the scan data pre processing Scan data pre processing ALASCA data Dirt Rain Ground Scan data 1 detection detection detection correction ALASCA data Dirt Rain Ground Scan data 2 opt detection detection detection et data Ego motion estimation Scan data Scan fusion data Vehicle Fig 44 Overview over the scan data pre processing The second ALASCA middle row is optional Currently up to three ALASCA s can be merged at the scan data fusion The scan data fusion module is available only if more than one ALASCA is connected 7 1 1 Dirt detection and range estimation If dirt accumulates on the cover of the integration chamber the sensor s range of view will be reduced In extreme cases e g a layer of slush on the cover the laserscanner even may get blind The vehicle computer and or the driver must be informed about the reduced performance due to dirt Therefor
51. hat do not need a perfect integration into the test vehicle body Fig 18 shows this housing The housing consists of the chamber and the adjustable mounting shoe Here only the vehicle connection has to be carried out by the customer Chapter 8 2 shows outline drawings and measures of the standard integration chamber The mounting shoe has six adjustment screws see red arrows in Fig 18 They allow for small pitch angle corrections within the range of the flexible rubber seal Please do not loosen any other than these six screws The warranty is void if the seal of any screw is broken Moreover the mounting shoe has six bolt holes Fig 18 A custom designed adaptor can be fastened here to connect the integration chamber to the vehicle body Fig 16 Example for an integration of the ALASCA into an Ibeo test vehicle In this case the ALASCA is mounted overhead housing light blue head brown integration chamber bolt holes gt f ii laser amp s scanner N pane i mounting Shoe l 6 adjustment screws i Fig 18 shows the Ibeo standard integration 2 screws hidden een i chamber from below The green arrows point to s x holes in the mounting shoe that can be used to Fig 18 Ibeo standard integration chamber fasten custom designed adaptor which connect to be integrated at the front centre of the vehicle the integration chamber to the car body Chapter 3 Handling and operating instruction
52. he high bandwidth of Ethernet it 1s possible to visualise both scan and object data with the ASD software from Ibeo Please refer to chapter 4 7 for details 3 3 Mounting the ALASCA The ALASCA should be mounted at the front of the vehicle with a clear field of view as wide as possible In addition some general rules should be obeyed Do not obstruct the field of view of the ALASCA If you mount the ALASCA behind a pane glass or acrylic plastic make sure that the pane is transparent for infrared light see chapter 3 4 Protect ALASCA s head and the interface connector from accidental damage e g due to collisions Integrate the sensor into the vehicle as described in chapter 3 4 or use simple metal barriers to avoid damage to the sensor The opposite figure shows an example of such a metal barrier for ALASCA s predecessor sensor LD ML When driving on public roads please note that there may be national statutory regulations that refer to such barriers and other restrictions may apply As Fig 6 shows ALASCA s lower red channel measures the ground at an incident angle of 1 6 looking ahead to 0 direction Depending on the application the sensor should be mounted at a height suitable for the wanted range of the lower layer The height refers to the distance of the mirror centre above the ground see also Fig 41 The ALASCA needs a sturdy mechanical mount in order to attach it to the vehicle body This moun
53. icrosoft Networks een ll Subnet mask 255 250 255 O0 Default gateway i Install Uninstall Properties Description Transmission Control Protocol Intermet Protocol The default Wide area network protocol that provides communication f obtain DNS server address automatically t Use the following ONS server addresses Preferred DNS server i i across diverse interconnected networks I Show icon in notification area when connected Alternate DNS server I Notify me when this connection has limited or no connectivity Advanced Fig 24 Changing the IP address of the host PC to connect to the ECU 2 Connect the ECU to the LAN local area network Maybe you need a standard CAT 5 Ethernet patch cable Alternatively you may connect the ECU directly to the host computer with the delivered Ethernet cross link cable 3 Start the program Servicelnterface exe Fig 25 from the Ibeo application CD ROM directory Tools Servicelnterface Insert the IP address of the ECU see label on the ECU and click on the button Stop Application to close the AppBase This operation does not stop the laserscanner h Servicelnterface 1 0 x Stop Application ECU Address U Disconnect Start Application Status ECU connected Fig 25 Service Interface 4 If there is a FTP program on the host computer start it Or you can use the freeware windows based FTP program FileZilla
54. ion is used whereas the continuous high resolution is used in a wider range of 60 around the x axis also in backward direction Within these ranges most of the relevant traffic objects can be detected at a good resolution The lateral range around the y axis has a lower resolution Finally the small angular range around the 180 boundary has a very low resolution The strut that holds motor and mirror obstructs the view of the laserscanner in this range The resolution values shown in Fig 11 are valid only for low rotation frequencies up to 12 5 Hz As listed in the previous table all resolution values are multiplied by 2 or by 4 at higher rotation frequencies so that resolution gets coarser Currently there is no user interface to change the default settings of the flexible angular resolution by the customer Upon request Ibeo can handle this task for the customer Note that the laserscanner must be sent back to Ibeo for this purpose X 12 5 Hz Fig 11 The ALASCA XT supports a flexible angular resolution The resolution depends on the relevance of each angular range for automotive applications For instance oncoming objects have a high relevance red area whereas lateral objects are usually less relevant The yellow low resolution area is obstructed by the strut that holds motor and mirror small black square 2 3 Scan data visualisation As shown in the previous section the reflection of a single laser pulse ca
55. justment Fig 20 shows an example of mounting and integrating the ALASCA In addition a specific mounting shoe is available from Ibeo upon customer request The mounting shoe in combination with a vehicle connector fixes the ALASCA against the vehicle body The shape of the connector depends on the specific integration situation and must therefore be custom designed mechanical connection between steel bumper and mounting shoe mounting pitch angle connector shoe adjustment custom designed Fig 20 left ALASCA with its mounting shoe and connector top ALASCA in upside down position with integration chamber behind the car bumper 3 4 3 Optical window For the optical window of the sensor integration chamber Ibeo recommends the infrared transmissive LUXACRYL IR Type 1698 thickness 1 5 mm for large bend radii as illustrated in Fig 21 Smaller bend radii of the window may be necessary i e for front bumper integration in trucks for applications like turning assistant which require a scan angle of up to 240 In this case optical reasons require a reduced thickness of down to 0 5 mm for a bend radius of about 100 mm For purchasing the optical window please check the TTV web pages www go ttv com filter filters htm Other colours than IR black except for grey may be chosen if required for design reasons To increase durability of the window the outer surface may be coated with a Chapter 3 Handling and operating ins
56. lt value is 10 m s Note that dx max 1S constant so that this parameter does not reflect the maximum possible deceleration given the tyres current grip simply because this grip is unknown Since an AEB application brakes only if a crash is un avoidable a max Must be set to the maximum deceleration possible at best grip Keep only those objects where the vehicle can escape neither to the left nor to the nght of the object To check this the current left and right escape radius is computed The escape radius 1s the smallest radius of a circular curve that the vehicle can take at the current velocity see and in Fig 47 It is computed using the formula escape vl yax where dy max is the maximum lateral acceleration This constant can be specified by the parameter dMaxCrossAcceleration m s default 5 m s As in the previous step here again a constant acceleration is assumed that is available only at best grip Since the escape radius cannot be less than the radius of the vehicle s turning circle this limit can be configured using the parameter dTurningCircle m default 11 m The following lines show an exemplary ANB section of the AppBase ini file with the default parameters Parameters for the AEB application ANB lt not AEB for historical reasons dEgoMinSpeed 2 78 dMaxObjectSpeed ae uMinObjectAge dVehicleWidth is uSystemDelayTime 100 nEscapeWayOffset 25 aDistOriginFront 0 6 uSystem
57. lue OX3FFF Factor 0 0055555556 0 02 1 m s 1 km h 0 02 3 6 Offset 0 UseLittleEndian TRUE Chapter 6 Object tracking 47 Example 2 Big Endian Note The bit numbers 0 to 63 are independent of the number of bytes transferred in the CAN message For example if only one byte is transferred only bit 56 to 63 is available For this example the following section should be specified in the ini file Velocity Tdent i rist 0X298 FirstBit 24 LastBit 37 SignBitAvailable TRUE SignBit 38 Brrorval es OxSFEF Factor 0 005 7995000 0 02 1 m s 1 km h 0 02 3 6 Offset 0 UseLittleEndian FALSE 6 4 Mounting position The mounting position of the laserscanner s must be known to convert the local coordinate system of each laserscanner to the ISO 8855 coordinate system of the vehicle see section 6 2 The coordinate transformation is composed of translations and rotations The origin is shifted by Ax Ay Az and there may be a rotation around each axis Aa Ag Ay From these six parameters the parameters Az vertical offset Ag and Ay roll and pitch angle can be neglected here because scan data is mainly evaluated using the bird s eye view cf section 2 3 Therefore the relevant parameters for detecting the mounting position are see Fig 38 e Ax Ay the offset in the ground plane and e Aa the horizontal angle offset yaw angle The transformation from lasersca
58. means of four scan planes at different vertical angles For clarity the vertical divergence is exaggerated here Chapter 2 Laserscanner ALASCA 5 The following table explains the naming convention for the channels and shows their default colours used for visualisation Channels are visualised by hue whereas echoes are visualised by saturation 0 0 0 8 1 6 0 25 Fig 6 shows the fields of view of ALASCA s four channels The cross section shown at the left end has the original aspect 30 15 0 15 30 Fig 8 The four fields of view are tilted when the mirror looks to different directions a Both the tilt angle and the mirror s direction always have the same angle a Chapter 2 Laserscanner ALASCA Fig 9 The same view as before but extended to one full revolution of the mirror The vertical axis 1s exaggerated for clarity The curves intersect the vertical axis at 0 4 and 1 2 whereas the horizontal axis is intersected at 90 0 4 and 90 1 2 Though the curves resemble the graph of the cosine function they are in fact shortened cycloids Fig 10 The three dimensional pendant to the previous graph The centre of ALASCA s mirror forms the origin of the coordinate system Again the z axis is exaggerated For details about ALASCA s coordinate system see chapter 6 2 2 2 3 Rotation frequency and angular resolution The motor that drives the d
59. ments of the current scan are matched with the predicted objects and the best matches are assigned More than one segment may be assigned to one object because parts of the object may be blocked from view by some smaller object in the foreground Finally the object properties position size velocity uncertainties are updated using the precisely measured position of the assigned segment This is done by updating the state vector of the object and running this vector through a Kalman filter Unassigned seg ments are stored as new objects with default properties After the object detection and tracking is complete for the scan the objects are sent to the host computer The information for each object consists at least of a set of points on the object outline including the leftmost rightmost and closest points a velocity and uncertainties for all values All information is given in both x and y direction in an ISO 8855 coordinate system see next section 6 2 ISO 8855 coordinate system For input and output the application uses a coordinate system according to ISO 8855 see 5 All angles are given in the range from 180 to 180 see Fig 35 Chapter 6 Object tracking 4 90 ss ALASCA seen from above 180 Fig 35 Coordinate system of the ALASCA If the ISO 8855 coordinate system is rotated by 90 clockwise it turns into the well known Cartesian coordinate system ISO 8855 assumes that the vehicle moves along
60. most applications The vehicle model takes as input the current velocity v and the front wheel angle a ESP data The latter one can be computed from the well known angle of the steering wheel using a cubic polynomial as transfer function Both v and a should be updated frequently min 10 Hz to ensure a good accuracy of the model The model yields for the point C or C the changes of position Ax Ay and yaw angle Aw relative to the previous output data of the model eee Cee eee Pree rrr rrr e o o o eee ee ee ce ooo o ee eee eee ee nc e n ey en nen nee TurningCircle lt 7 DistOriginFront diameter O Ri ee rv eae CenterToFrontAxle C Se VehicleLength Bi CenterToRearAxle R EKR _ BEE ree eee Cree ree e o e v elo VehicleWidth Fig 42 Parameters of the vehicle model O centre of the front axle origin C centre of gravity C alternative centre 1 2 O R R centre of rear axle The vehicle width does not include the side mirrors Chapter 7 Software 52 7 Software This chapter describes the individual software modules The structure of this chapter resembles the data flow from the laserscanner to the application ALASCA Scan data pre ev pplication scan data processing Chapter 7 1 Chapter 7 2 Chapter 7 3 Fig 43 Overview over the data flow from the sensor to the application Please note that depending on your system con
61. n be converted to a point P given in polar coordinates d a relative to the sensor where d distance o yaw angle azimuth angle horizontal angle pitch angle elevation angle vertical angle Such a single point is called a scan point During scan data processing each scan point is converted to Cartesian coordinates P x y Z During one revolution of the mirror a multitude of laser pulses is transmitted resulting in a set of scan points Pj Pn the so called scan The number of detected scan points n may vary from one scan to the next e g due to object movements in the surroundings For visualisation the scan points are usually plotted in a rectangular two dimensional 2D coordinate system the scan view but they can also be overlaid to a video image projected in perspective Fig 12 shows an example of both visualisations for the same scene When comparing the visualisations please keep the following items in mind e The scan view shows the scan in bird s eye view whereas the video image shows the scan in camera or human s eye view In Fig 12 exemplary groups of corresponding scan points are encircled pink and connected by arrows e The camera has a view angle that is much less than the laserscanner s maximum view angle Thus not all scan points in the scan view have a corresponding point in the camera view In Fig 12 only those scan points can be found in both visualisations that lie betwe
62. n detail in section 7 3 1 ComPort 1 Specifies the RS232 port BaudRate 38400 Specifies the Baud rate bits s Use only valid rates for RS232 2400 4800 9600 19200 and 38400 6 3 5 Section Vehicle This section of the ini file describes the vehicle s geometry The parameters listed below are shown together with exemplary values CenterToFrontAxle 1 409 see Fig 42 CenterToRearAxle 1 291 DistOriginFront 0 932 TurningCircle 11 0 VehicleWidth 1 745 VehicleLength 4 682 For calculating the vehicle movement from the velocity and the steering angle some vehicle parameter are necessary The transmission ratio of the steering 1 e the ratio between the steering wheel angle and the front wheel angle is given as a third order polynomial with the four coefficients SteerRatio0 SteerRatio3 Two different definitions of the polynomial are available type 0 and type 1 The choice between these types depends on the data available from the vehicle manufacturer Type 0 Transmission ratio Let x be the steering wheel angle in degrees Then the transmission ratio is defined as Chapter 6 Object tracking 45 TransmissionRatio SteerRatio3 x SteerRatio2 x SteerRatiol x SteerRatio0 The front wheel angle is calculated from the steering wheel angle by FrontWheelAngle x 1 095 TransmissionRatio SteerRatioType 0 The following coefficients belong to a transmission ratio polynomial SteerR
63. nner to ISO 8855 coordinates is performed as follows 1 Laserscanner coordinates convert Cartesian x y to polar r a 2 Rotation by Aa r a r a Aa back to Cartesian x y 3 Translation by Ax Ay x y x Ax y Ay 4 TSO 8855 coordinates x y The mounting position can be determined manually or automatically Note that even though the automatic determination appears to be more attractive at first sight the manual alternative is usually much faster and has a similar precision Chapter 6 Object tracking 48 Fig 38 For the transformation from laserscanner coordinates green cf Fig 35 to ISO 8855 coordinates black the displacement Ax Ay and the angle offset Aa red must be known 6 4 1 Manual determination The ASD visualisation software from Ibeo allows setting the mounting position manually The mounting position is entered in the Parameter property page of ASD see Fig 39 e The offset in the ground plane Ax Ay can be measured directly e g using a tape measure Often the offset can also be determined from CAD data In the Parameter property page of ASD assign Ax to the parameter Offset X and Ay to Offset Y e To determine the horizontal angle offset Aa manually place the vehicle next to a long plain wall e g side of a house so that the 0 direction of the vehicle is exactly parallel to the wall In ASD tune the parameter Horizontal angle offs
64. object tracking is complete the objects are sent on the CAN bus Before sending the objects they are sorted in order to send the most relevant object first The following sorting criteria are available 0 Radial This quality criterion is the simplest of all sorting criteria It sorts the objects by their distance from the centre of the vehicle coordinate system so that the closest object is sent first Note that due to the possible offset between the sensor position and the origin of the coordinate system the first object is not necessarily the object that is closest to the laserscanner 1 Look Ahead The look ahead criterion sorts objects by a roughly club shaped area of priority The axis between the origin of the coordinate system and the centre of the look ahead criterion at position 15m Om has the highest priority while objects further to the sides have lower priority see Fig 36 This criterion takes Chapter 6 Object tracking 43 into account the typical forward movement of a vehicle prioritizing objects in front of the vehicle higher I9 1U 9 U o 1U 19 30 4 20 0 High priority object 100 Medium priority object 70 0 e Low priority object lt 70 Own vehicle 10 Fig 36 Distribution of the priorities at the look ahead criterion red high priority 100 violet medium priority 70 The priority continues falling outside the coloured area the limitation to 70 100 is for
65. of scan points N x 12 bytes Version number of the data structure current version PadByte UINTS Unused just for proper memory alignment _______ TimeStamp UINT32 3 Time stamp of the scan in milliseconds _________ Scan start angle rad x 10 Endingle INTIe 1808888 coordinare ysten IS ScanCounter UINTI6 1 Consecutive scan number s NumPoints N UINTI6 1 Number of subsequent scan points SubChannel UINTS 6 Zero based sub channel 0 A 1 B ______ PointStatus UINT8 7 Point canbe ground rain dirt etc _____________ rip Cartesian coordinates of the point according to z ISO 8855 except for z coordinate see note 8 ZCoord INTI6 nn UINTI6 rer invalid or not available arbitrary unit Chapter 4 Electronic Control Unit ECU 30 Note 1 Integer value no decoding necessary Note 2 Currently known scanner types are 0 LD Automotive 1 LD ML 2 ALASCA These values are also defined as constants SCANNER _TYPE_ in ASL h Note 3 The integer value represents a reference time stamp given in milliseconds when the scanner measures to its 0 direction ahead Exception If there is only a single laserscanner no fusion system and this scanner 1s mounted in the rear of the vehicle the 180 direction backwards is used as reference time stamp Due to the rotation of the scanner s mirror it takes some time to collect th
66. of this size even if the message size 1s much smaller during normal operation Since all object data are UINTS i e bytes the Endianness does not matter here 4 7 4 Decoding scan data A scan data message has file type 15 FILE_TYPE_COMPRESSED_SCAN This message contains a subset of the scan data information so called compressed scan data The com pression removes internal administrative information from the scan that is not relevant for the scan data receiver The message length depends on the number of scan points N in the current scan The theoretical maximum number of scan points depends on the scanner type the angular scan range and resolution For an ALASCA there are N lt 8 648 points max 270 scan range in cluding start and end angle x 4 channels x 2 sub channels 0 25 resolution 1 081 x 4 x 2 In this case the message size is lt 103 808 bytes 2 x 16 8 648 x 12 see Fig 28 Chapter 4 Electronic Control Unit ECU 29 The message body contains the compressed data of a single scan As Fig 28 shows the message body is subdivided into a scan header 16 bytes followed by a sequence of N scan points 12 bytes each The following tables show the structure of the scan header and scan points Ethernet message Message header 16 bytes Message body Scan point N 1 Fig 28 Structure of the message when receiving compressed scan data The total message length is 12N 32 bytes where N is the number
67. on the external synchronisation signal should remain in high state for at least 1 ms in order to allow the SyncBox a stable detection of the signal Since the connected laserscanners will derive both their scan frequency and head position from the trigger input signal care must be taken that this signal 1s within the specification of the connected laserscanners If the trigger signal frequency exceeds the limits of the scan frequency the laserscanner will go to error mode and report this in its scan data sensor status field Accordingly if the input signal has a high time jitter the laserscanners will be unable to synchronise to that signal In this case a jitter warning signal is generated SyncBox Trigger output ARCnet RS232 Fig 30 System layout in timer mode internal triggering SyncBox Trigger input lt lt gt Trigger output T gt Jitter warning RS232 ARCnet RS232 ECU Fig 31 System layout in bit I O mode external triggering Chapter 5 SyncBox 5 4 SyncBox LEDs and connectors This section describes the LEDs at the front of the SyncBox see Fig 32 and the connectors at the backside Fig 33 The used connectors are not waterproof Therefore the SyncBox must not be exposed to water Power supply on Bit I O mode Sync0 1 J Reserved for future use Fig 32 Front side of the SyncBox D z O A 9 m Reserved Fig 33 Back side of the SyncBox n c
68. on signal Also for a correct synchronisation the scan area must contain at least the angular range from 5 to 5 It is important that synchronisation frequency and scan frequency are approximately the same otherwise the controller will fail to synchronise Therefore the configuration parameter RotationFreq see section 6 3 2 should be equal to fsync 5 2 System layout in timer mode The SyncBox connects to the laserscanners via RS232 by means of the ECU In the configuration shown in Fig 30 the SyncBox sends its signals to the ECU that distributes them to the laserscanners The SyncBox runs in timer mode generating the synchronisation pulses internally Each trigger time also causes a 5 ms high pulse on the trigger output which allows triggering external devices at the same time To run in timer mode the SyncMaster parameters in the file AppBase ini must be set to FALSE in the sections Sensor_n syncMaster FALSE Note that the same system layout applies if only one laserscanner is connected 5 3 System layout in bit I O mode In bit I O mode the trigger signal is supplied by an external source to the trigger input of the SyncBox Fig 31 Upon receiving a low to high transition on the trigger input the synchronisation commands are sent to the laserscanners The signal is also acknowledged by setting the trigger output signal for 5 ms see chapter 5 5 for detailed timing examples Note After the transiti
69. onding kind of data As shown in Fig 14 each connection transmits a certain kind of data ALASCA ECU connector cable raw data Here the ALASCA sensor sends its hardware measurement data to the ECU This data is called raw data because it needs further processing by the ECU Raw data is transmitted from the ALASCA to the ECU only not to the vehicle computer This connection uses an ARCnet bus for data transmission CAN object data A condensed high level description of the scan data is sent as object data on the CAN bus to the vehicle computer Ethernet object and scan data While processing in the ECU the raw data becomes scan data 1 e a collection of scan points see section 2 3 The optional Ethernet connection transmits scan data for debug or visualisation purposes In addition to the CAN bus object data is sent over the Ethernet interface too Usually scan data is of interest for humans only Humans can intuitively group interpret and assess scan data in the context of a traffic situation A standard vehicle computer does not have this intelligence Therefore the ECU acts as a pre processor for the vehicle computer Software algorithms on the ECU transform low level scan data to high level object data like object no 4 is a car 30 metres ahead driving at 50 km h see also chapter 6 1 3 2 1 Power supply The ECU requires a 12 V DC 20 W power supply Typical power consumption of the stand alone ECU is less than 12 W N
70. onnected to the ECU and the special SyncPlug must be inserted into the serial connector of the ECU The SyncPlug is delivered by Ibeo Chapter 6 Object tracking 40 6 Object tracking 6 1 Overview The ECU computer runs a complete object de tection and tracking algorithm on the ALASCA scan data This algorithm splits the scan data into objects and tracks those objects through sub sequent scans The result is instead of the scan data a set of object data with information for Se each object like position size outline and eee velocity The object data is sent to the host system on a standard CAN bus This frees the Get segment host computer from the task of isolating the characteristics relevant information from the huge amount of scan data that the laserscanners produce An overview of the standard tracking algorithm is shown on the right After receiving the scan it is split into segments Segments are clusters of scan data that are believed to belong to one object Then the characteristics for each segment are calculated such as the position size and number of scan points At this stage of the algo Fig 34 Structure of the object tracking rithm all those characteristics are purely static In parallel the prediction of the object movement is calculated using the output of a Kalman filter All objects are extrapolated from the previous scan by one step to predict their position in the current scan Then the seg
71. origin is located at the middle of the rear axle If the offset Ax Ay shall be determined automatically too the bisector of the V angle must lie exactly on the x axis red dotted line in Fig 40 Any angular error directly propagates from here to Aa The main and time consuming challenge of this procedure is to find the exact position of the reference point Per in front of the vehicle 6 4 3 Vertical alignment ref Fig 40 Calibration field for the automatic mounting position detection with ASystemSetup 49 The multi layer technology of the ALASCA is useful e g for pitch angle compensation cf Fig 5 To work as expected the laserscanner must be vertically adjusted so that it is aligned parallel to the ground plane For this purpose an adjustable mounting shoe is recommended as shown in Fig 20 Two methods to adjust the vertical alignment are presented below Preparation to adjust the vertical alignment see Fig 41 e Place the vehicle on flat ground and make sure the ground is level up to 10 m in front of the vehicle e Place the standard load in the vehicle e g a driver and a passenger e Activate the laserscanner It must be actively measuring If the object tracking application AppBase 1s running on the ECU it activates the laser automatically e Measure the height ho above ground of the beam at the position of the scanner This is the distance from the ground to the middle of the mirror of the las
72. ossible It is also protected against reversed polarity However in case of a reversed polarity a critical current may flow through the data lines and destroy the SyncBox and or connected devices 5 8 2 Bit I O The bit I O outputs of the SyncBox are TTL compatible with a 5 V level and push pull driver stage Therefore multiple outputs must not be connected together and outputs must not be connected to ground externally No output signal may drive more than a 2 mA load both to high or low level A low signal is a voltage level of 0 0 0 7 V a high signal is a level of 2 4 5 0 V The inputs are connected internally to 5 V with 20 kQ pull up resistors In order to input a low signal external devices must pull this level below 0 7 V Do not apply high voltage or transients to the signal lines as this will destroy the internal components 5 9 Synchronisation without SyncBox The ALASCA also supports a self synchronising mode In this mode one ALASCA master transmits its 0 time to a second ALASCA slave The slave then adjusts its own mirror movement to match the master exactly To enter this synchronisation mode the AppBase ini file must be edited as follows One sensor must have set SyncMaster TRUE e g in the section Sensor_O and the other one SyncMaster FALSE e g in section Sensor_1 FALSE is the default value for the parameter SyncMaster In order to synchronise in master slave mode the two ALASCAs must be c
73. ote that the ECU also supplies power to the connected sensor s which will increase the current on this power connector approx 12 W per sensor The system may be directly connected to the vehicle power supply of 12 V nets In order to avoid damage due to overvoltage an additional DC DC converter can be inserted A suitable DC DC converter is available from Ibeo In order to ensure the proper function of the system do not use this converter to supply power to other devices too The supply voltage is 12 to 15 V DC Never operate the system outside this voltage interval Do not reverse polarity Chapter 3 Handling and operating instructions 1 3 2 2 ALASCA ECU connector cable The connector cable is used for communication between ALASCA and ECU It includes power supply for the sensor an ARCnet bus for data transmission and a RS232 interface for sensor synchronisation The latter one is described separately in chapter 3 2 4 For ALASCA sensors a power supply only between 12 and 15 V DC may be used The standard connector cable delivered by Ibeo directly passes the external ECU power supply on to the sensor s Inside the ECU there is no special power supply unit for the sensor The ARCnet bus in the connector cable is used to send commands from the ECU to the sensor and to receive raw data from the sensor at the ECU ARCnet is a bus system which must be terminated at both ends of the bus Termination reduces reflections on the c
74. r AppBase the units are converted to more common and user friendly units like km h or degrees If the parameter is not encoded please set Factor to 1 and Offset to 0 Take the steering angle parameter as an example Assume a conversion factor of 0 5 per integer value and an angular offset of 10 The actual parameters can be found in your CAN specification Factor and offset must be converted to radians yielding Factor 0 5 z 180 gt 0 008727 and Offset 10 z 180 x 0 174533 UseLittleEndian Defines if the data is encoded in Little Endian TRUE or Big Endian FALSE For more information about Endianness please refer to page 27 Example 1 Little Endian The example describes how to get the velocity parameter out of a CAN message with the identifier 0x288 Let the velocity be encoded in byte O and byte 1 coloured in light blue in the following table and there is a sign bit coloured in dark blue The parameter is encoded using a factor of 0 02 an offset of 0 and the original unit used by the vehicle is km h A CAN message has 8 bytes with 8 bits each Byte O starts with bit 0 and ends with bit 7 Byte starts with bit 8 and ends with bit 15 and so on Pits sae Dn Ps es os 3 2 61 00 59 38 37 56 For this example the following section should be specified in the in1 file Velocity Identifier 0x288 FirstBit 0 LastBit 13 SignBitAvailable TRUE SignBit 14 BrrorVa
75. r state If the traffic situation becomes more dangerous and an obstacle is in the way to stop the AEB switches to the warning state In this state the driver still can avoid the crash by steering but time consuming reversible safety measures e g the brake booster pressure up can be prepared now If also steering cannot avoid the crash anymore the AEB state is set to alarm and an external system is signalled to initiate the emergency braking To check that the driver cannot avoid a crash neither by braking nor by steering the AEB algorithm assumes the following facts e The maximum cross acceleration that the driver can control while steering is constant default 5 m s e Since the grip of the tyres is unknown for the way to stop ahead a constant coefficient of friction is assumed e The maximum deceleration is constant default 10 m s The AEB algorithm takes vehicle and object data as input From th s information the r sk of a collision is assessed This is done by a chain of object filters where each filter checks a certain AEB criterion Objects that fail to pass a filter are ignored in the remaining steps of the filter chain If any object passes all filters a collision with this object is unavoidable and an emergency braking must be initiated The following list explains the filter chain in detail The filter parameters can be set in the section ANB of the file AppBase ini see example below 1
76. rol Unit ECU 24 4 3 LED signals The tracking software running on the ECU is called AppBase The LEDs of the ECU show the current state of ECU and AppBase Power supply on yellow off ECU start up phase approx 45 sec neither AppBase running nor sensor connected yellow quickly The sensor is connected but AppBase 1s not yet running flashing AppBase tries to connect to the sensor but the sensor is not connected flashing Data transmission on the ARCnet bus between ECU and sensor Data transmission on the Ethernet 4 4 Start up and shut down The AppBase software is started automatically after booting the ECU It takes approximately 45 seconds to boot the ECU Unlike a PC the ECU needs no preparation to shut down It can be shut down at any time simply by removing power 4 5 Software Updates The AppBase software on the ECU and consists of three files AppBase exe AppBase ini and AppBase dat It is not always necessary to update all three files The following steps describe the update process on a Windows system 1 Modify the network configuration of the host PC to get the ECU connected e This operation requires administrator privileges e Open the network settings by clicking on Start Settings Network Connections In the Network Connections dialog click with the right mouse button on the icon of the Local Area Connection and select Properties to open the Local Area Connection Properties dialog
77. rotection e Collision Warning e Turing Assist e Park Assist e Please visit www ibeo as com to get informed about the latest applications for your laser scanner 60 Chapter 8 Physical dimensions 8 Physical dimensions 8 1 ALASCA All measures are given in millimetres OPTICAL AXIS ALAISCA M6x6 deep Automobiler i RES 126 25 CABLE GLAND PG7 Weight approx 1 5 kg including the flexible rubber seal not shown here 8 2 Standard integration chamber 8 2 1 Housing All measures are given in millimetres metna thread inserts M5 x 10mm 8 2 2 Mounting shoe holder All measures are given in millimetres 301 z 120 82 55 102 39 Bz a6 17 37 17 37 g Weight approx 1 0 kg 63 Chapter 8 Physical dimensions 8 3 ECU All measures are given in millimetres Ethernet Connector Power Connector D Sub 9 polig D Sub 15 polig 3x 30 Weight approx 2 6 kg 8 4 SyncBox All measures are given in millimetres oO m u o a RS232 0 Weight approx 1 1 kg Chapter 9 References 65 9 References 1a 1b 2 3 4 Sa 5b European Committee for Electrotechnical Standardization EN 60825 1 Safety of laser products Part 1 Equipment classification requirements and user s guide IEC 60825 1 1993 A2 2001 Internet www cenelec org Deutsches Instit
78. roups of scan points that are believed to belong together e g due to geometrical correspondence These groups are called segments The separation of such segments is determined by a decision function which is currently the distance between the scan points For details refer to the parameters MinDist and XYFactor in chapter 6 3 2 An object may be built up of many segments but each segment may belong to at most one object 7 2 2 Contour tracking This module performs the actual object tracking based on the segments that have been found in the previous step Each segment is considered as a part of one object s contour hence by tracking segments we track object contours An object is tracked by first extrapolating its movement from the previous scan to the present scan This prediction forms the seek area where in a second step the actual object position in form of one or more segments is found by a best match comparison 7 2 3 Classification Based on the properties of the objects the classification module labels each object with a type Available classes types are e Pedestrian e bike e car e truck e unknown big and unknown small Chapter 7 Software 3 This information is used by high level applications that have to evaluate objects depending on their type The object class is included in the object data of the CAN output Note The classification is improved if vehicle data is available because then the objects
79. rs e 2x Sensor 15 pin D Sub female e 1x serial port 15 pin D Sub male e 1x CAN 9 pin D Sub male e 1x Ethernet RJ45 e 1x Power For the basic setup of the system please refer to Fig 13 Serial opt CAN Power ALASCA 2 ALASCA 1 LAN see text Network Fig 23 Interfaces at the rear of the ECU 4 2 1 Interfaces The ECU has the following interfaces see also Fig 13 e Power The ECU requires a 12 V DC 20 W power supply Its connector cable has a red plug for 12 V and a black plug for ground GND Typical power consumption of the stand alone ECU is less than 12 Watts Note that the ECU may also supply power to the connected sensors which will increase the current on this power connector see also section 3 2 1 e ALASCA 1 Connects laserscanner and ECU see section 3 2 2 Its pinout is directly compatible with the ALASCA e ALASCA 2 This connector is for an optional second laserscanner The pinout is the same as for connector ALASCA 1 To connect a second ALASCA successfully Ibeo must prepare the ECU specially By default the ECU supports only one laserscanner e CAN The ECU is equipped with a standard CAN interface Application data is sent and received on this interface see section 3 2 3 Chapter 4 Electronic Control Unit ECU 22 e Serial This connector holds the serial port of the ECU COMI as well as the serial interface of the ALASCA connector It can be used to connect the SyncBox for th
80. s 15 For transportation safety Ibeo delivers each integration chamber with a protective plastic film on the pane Please remove this plastic film before using the laserscanner for the first time Otherwise the laserscanner will show bad performance Integration chambers from Ibeo are delivered with a waterproof built in laserscanner Neither open the integration chamber nor remove the built in laserscanner as this will result in a leakage that may damage the laserscanner Do not drill holes in the integration chamber 3 4 2 Designing a custom integration chamber The integration chamber can be designed by Ibeo based on custom requirements or by the customer alone In the latter case some design rules should be observed that are described in this section Please contact Ibeo if consulting on this topic is desired First determine the optimum position of the ALASCA in the test vehicle regarding your application Note that the ALASCA main axis must aim at that direction where the full 3 2 vertical divergence is required cf Fig 10 Define the horizontal field of vision scan range and conclude the requirements on the dimensions of the integration chamber Due to the vertical divergence of the field of view consider 6 cm free field of view for the vertical extension of the optical window as illustrated in Fig 19 The optical window should be vertically tilted at no less than 22 see also next section for details optical window
81. s age Now if e g a bush suddenly penetrates through the crash barrier into the vehicle tube AEB will trigger an alarm because in the object data the bush is merged with the crash barrier and this merged object intersects with the vehicle tube To avoid this problem a blind range is installed directly in front of the vehicle see in Fig 47 The size of this range depends on the velocity of the vehicle Therefore it is specified in milliseconds the so called system delay time The actual blind range results from the product of the system delay time and the current velocity The parameter uSystemDelayTime ms defaults to 100 ms It must not be greater than 10 000 ms 5 Keep only those objects that have a distance less than the vehicle s way to stop see in Fig 47 This way is mainly composed of the way to reaction of the AEB system and the way to brake Way to stop Xstop K Xreact Xbrake Xo Way to react oe VE Way to brake Xbrake V 24x max k is a stretch factor that models the reduced deceleration when braking in a curve As will be shown in the next step the AEB application checks if the vehicle can escape in a curve to the left or right of an obstacle The parameter nEscapeWayOffset specifies the percentage that is added to the normal straight on way to stop 1 e k 1 nEscapeWayOffset 100 For instance 0 implies Xstop Xreact Xbrake Xo the normal way to stop and 50 implies Xstop
82. t should allow for a vertical adjustment of about 5 to 10 With this range the customer will be able to adjust the proper vertical zero degree line Horizontal adjustment is not required if the design warrants a maximum horizontal angular error less than about 2 Although it 1s possible to compensate for arbitrary angular errors by software cf chapter 6 4 you should keep in mind that the divergence of the scan layers is maximal only in the sensor s 0 direction see Fig 10 Thus significant differences between the 0 direction of the vehicle and the sensor will result in a reduced capability to compensate pitch angles The ALASCA may also be mounted upside down In this case the processing and visualisation must be informed that the sensor is upside down because the location of the vertical scan planes and the scan direction is reversed see parameter SensorUpsideDown in section 6 3 2 3 4 Integration into the vehicle For professional automotive applications the laserscanner should be integrated into the vehicle Fig 16 shows the integration at the front centre of a test vehicle Other integration positions may be located at the front left and right corner or the rear of the vehicle The following subsections describe the standard integration chamber offered by Ibeo and give guidelines for custom designed integration chambers 3 4 1 Ibeo standard integration chamber Ibeo offers a standard integration chamber to customers t
83. th the cleaning solvent and gently wipe mirror and pane If stains still remain after the first cleaning repeat this procedure with a fresh cloth 4 Electronic Control Unit ECU The ECU is the platform that runs the signal processing algorithms It reads the scan data of one or more laserscanners via the ARCnet interface and sends the resulting output on CAN and Ethernet interfaces aA N et A f Z ff f pi yryvyvrvyy Fig 22 The Electronic Control Unit ECU 4 1 Mounting the ECU The ECU may be mounted in any desired position or location However some general rules should be obeyed e Fasten the ECU in its mounting position to prevent the housing from crashing about causing damage to itself and other components e Protect the ECU from shocks and heavy vibrations Although the system does not contain moving parts excessive shocks may cause damage to the system or loosen connectors e Use at least 0 75 mm cables to connect the ECU to power Using cables with a smaller diameter may cause the cables to overheat e Keep the ECU away from water Although it is waterproof exposure to water will not increase the life expectancy of the ECU Note that although all interface connectors are waterproof they will become watertight only if there is a matching also watertight con nector or end cap mounted to them Chapter 4 Electronic Control Unit ECU 21 4 2 Connecting the ECU The ECU has the following connecto
84. tion or suggestions for improvement are always welcome II Table of contents 1 2 Q9 Tne sn e M R o a zoyyxxyazcryrmnbbbrbrrbebebbbbbb e e n a MMMUVMIDIZIZ RaID ZE 1 Las est AI Foret acess E E A 2 2 1 ERE onina Le MZzrcD_r raa a xxx2mrmrpxpxpmpxg T 2 22 PRC IPO rr Sl De ee ee ee ee gr 2 22 1 Multi tarser capabihty aeeene ae 2 222 Multi layer TECHNOLO ny euere eier 4 22 Rotation frequency and angular resolution k ne 6 2 3 SCAN AA NIS BA SALON E E ee a E nase 7 Handling and operating instructions EL EEE ek k k k k KAKA K KK K KA 9 3 1 FE 2G E h EE cceise sean snagnioe sve secon snag xxgxgeeerepp rzrJzJrz ee 9 3 2 Connecting the AL S keke eke eee eee ek Eke k K k KK KEK K KH HA KAKE KE KAKA HA KK KEKE KA HA 9 32 1 Power SU LT MN oororararXWXrXaXRTXXXRaRrRr r teaaeinaee 10 i ALASCA ECU connector cable keke keke keke 11 323 FAN CONNECTION ee ee re see 12 3 2 4 RS2 2 CODN Sel le yx N E T N 12 3 2 5 Eih inel conn CO re rp 2 2XRxp_ _ 22 2 20 13 3 3 Mounl ne ME ALASCA een 13 34 PPA normale 14 3 4 1 Ibeo standard integration chamDer keke k r 14 3 4 2 Designing a custom integration chamDer ne 15 3 4 3 ECA WIN OWN 16 3 5 Damage to the laserscanner iy icsirxn siwan d n xan n asl kalak e een 17 35 M AND casein cl os ating E ances o _eararnbbe emr eEeEePE E 18 3 6 1 enda Se NSO ae na nee 18 3 6 2 C
85. tructions 7 hard coating This coating must be professionally applied in a clean environment For a first go however the plastic material may be used uncoated The optical window should be formed from a plane sheet of plastic The plastic window can be bent horizontally according to the requirements of the integration chamber The plastic window must be made from one piece without any parts in the way e g heating wires For optical reasons one should refrain from a full three dimensional forming of the plastic material surface because this leads to undesirable optical distortions Also for optical reasons the window must not be positioned perpendicularly to the direction of the laser beam This would lead to an optical short circuit due to direct reflections and it significantly reduces the sensitivity of the ALASCA It must be ensured that for all scan angles the laser beam reflected back from the optical window would not re enter the optical system of the ALASCA For illustration purposes Fig 21 shows the top view onto a left side integration chamber Here laser beam 1 is drawn at the critical scan angle range around 45 At this horizontal angle only a vertical tilt of the window can prevent the internal reflection to directly re enter the ALASCA For other scan angles the reflection from the window is unable to re enter the optical system of the ALASCA because of the large horizontal incidence angle In terms of numbers the vertical
86. tween adjacent beams This makes the position detection procedure somewhat tricky because of crosstalk between adjacent beams Repeat the previous step for at least one different direction e g 45 or 90 to correct a possible roll angle of the sensor After this correction the scan plane should be parallel to the ground level and the mirror centre should lie inside the scan plane 6 5 Vehicle Model Without further precautions any non linear ego motion of the vehicle reduces the quality of the PreCrash information For example if two vehicles run the risk of colliding in a curve the quality of the estimated time to collision TTC can get unacceptable low Knowledge about the ego motion helps to improve the TTC quality for non linear motion This knowledge comes from a vehicle model that describes the physical behaviour of the vehicle given its current velocity and steering angle Using this model a non linear ego motion can be predicted better and the TTC quality is improved Furthermore the known ego motion can be subtracted from the other objects motion to get their absolute velocities These results are helpful input e g for object classification Chapter 6 Object tracking 51 Fig 42 shows the parameters of the vehicle model If the position of the centre of gravity C is not known the centre may be shifted to C half way between the centres of the front and rear axle The error due to this displacement is acceptable for
87. twisted pair ARCnet in and out to another twisted pair e Please also refer to the separate manual ARCnet documentation 2 3 2 3 CAN connection The CAN connection transfers data between the ECU and the vehicle computer Object data ECU vehicle computer Vehicle data ECU lt vehicle computer Application data ECU gt vehicle computer Parameter data ECU lt gt vehicle computer CAN is a bus system that must be terminated at both ends of the bus see Fig 15 The terminator must be integrated into the cable or an external terminating adapter plug must be used available from Ibeo For details on installing and using the CAN bus see the separate CAN hardware and user manual CAN documentation Each message sent on the CAN bus is labelled with a numerical message identifier ID This numerical value also implies the message priority where ID 0 means the highest priority The CAN messages sent by Ibeo use only a few identifiers see also parameter CANBaselD in section 6 3 2 e one identifier for communication from the vehicle computer to the ECU e another identifier for the opposite direction of communication and e some identifiers for high priority communication e g automatic emergency braking To distinguish between messages sent with the same identifier each message type is individually identified by a message type value inside the message The ECU also includes state information into a certain
88. ut f r Normung e V DIN EN 60825 1 Sicherheit von Laser Einrichtungen Teil 1 Klassifizierung von Anlagen Anforderungen und Benutzer Richtlinien Internet www din de Ibeo Automobile Sensor GmbH ARCnet Documentation Ibeo Automobile Sensor GmbH Specification of the CAN message protocol for Ibeo Automobile Sensor GmbH Laserscanners Till Heinrich Bewertung von technischen Ma nahmen zum Fu g ngerschutz am Kraftfahrzeug Technische Universit t Berlin ILS August 2003 International Organization for Standardization ISO 8855 1991 Road vehicles Vehicle dynamics and road holding ability Vocabulary Internet www iso org Deutsches Institut f r Normung e V DIN 70000 Stra enfahrzeuge Fahrzeugdynamik und Fahrverhalten Begriffe edition 1994 01 ISO 8855 1991 modified Internet www din de

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