!DANGEROUS HIGH VOLTAGES

ARE PRESENT IN THIS EQUIPMENT

CHAPTER 1COMPONENT OVERVIEW

AC THEORY OF OPERATION

Always use the “One Hand Rule” when working with AC voltages by keeping one hand in your pocket or be-hind your back. Before removing wires from the Aligner, always verify that the unit is “OFF”. Turn off the Main Power Switch on the back and unplug the AC power cord from the AC outlet.

AC DISTRIBUTIONThe primary voltage applies 110/220VAC, 60/50Hz AC to the ALIGNER via the hot side (Black Wire) of the AC power cable. The Main Power routes to one power strip. The power strip distributes 115’/220V AC to the PC, Monitor, Printer.

COMPONENT IDENTIFICATION

MAIN BOARD

The Main board is design to functions as the system master and contains the image processing DSP, the “Supervisor” ARM processor, SPI bus multiplexer, connections for each module as well as power supplies for each processor and module. Each power supply is designed and optimized for power conversion effi ciency greater than 95% in-order to provide extended battery life. The Main board can be thought of as two boards or primary functions combined into one board. These two primary functions relate to the image processing DSP and system management by the Supervisor. The Supervisor and DSP communicate through the DSP Host Port Interface which gives the Supervisor complete access to the DSP’s on-chip registers and external RAM and Flash memory space. Main board; Supervisor (ARM 9 microcontroller)The Supervisor’s main functions are power conservation, data communications, system integrity and user interface. The Supervisor continuously confi gures and initiates each phase of operation and then cycles the pod through systematic sleep periods. By choreographing and limiting the precise time that each module as well as the DSP is awake and consuming power, the Supervisor can dramatically extend the runtime from each battery charge. The Supervisor can monitor angle change activity and reduce data acquisition frequen-cy if no change has been detected for a pre-determined amount of time. In this way the pod can conserve power if the user has walked away or forgotten to turn the system off. The data acquisition frequency can be reduced on a schedule such that the longer the system senses no activity the longer the sleep state duration. The moment any angle movement is detected the system can acquire data at full rate thereby maintaining the responsiveness required for wheel alignment. The Supervisor may also be confi gured to reduce the data acquisition frequency on a critically low battery condition thereby moderately sacrifi cing measurement read-ing update rate for an extended battery life. The Supervisor monitors temperature, power supply voltages, current, and communications data integrity to ensure that all systems are working properly. Data from the DSP, modules, power monitoring systems, and keypad are consolidated, packetized and sent to the compan-ion head via the IR link and to the console via the Bluetooth radio. All failures are reported to the user by communications with the console (Bluetooth), companion head (IR Comm) and keypad (LEDs). The intent is to validate any failures to the extent that the pod or system can indicate the need for service without fear or

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CHAPTER 1 COMPONENT OVERVIEW

doubt of false failure indication. This operational confi dence can also assist the user in discerning procedural or training issues from real pod or system failure modes.

Main board; DSP Image processor (TMS320DM642)The DSP executes fi rmware independent of the Supervisor and therefore operates autonomously. By imple-menting the Host Port Interface (HPI) the Supervisor can coordinate when the DSP is active or in sleep mode in order to conserver power. The DSP’s primary function is to acquire image data from the image sensor and derive the target plane orientation using Snap-on proprietary image processing algorithms. In addition, the DSP can perform many of the Supervisor’s functions as an alternate system controller, including radio com-munications, in case the Supervisor has failed. As required, the DSP can take control of the system and send all failure data to the user by communications with the console (Bluetooth), companion head (IR Comm) and keypad (LED). In addition, the DSP can operate in a “limp mode”, performing all alignment functions, although at a much greater current drain. This would allow the user to operate for a short time in-order to complete an alignment should the Supervisor fail completely.

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CHAPTER 1 COMPONENT OVERVIEW

CAMERA MODULE

The Camera module implements the Omnivision OV9121 image sensor with 1280x1024 pixel image reso-lution. The image sensor setup, exposure time, gain settings and image acquisition is controlled by an on-board Freescale MC9S08 low power microcontroller. The MC9S08 communicates with the Main board Supervisor ARM 9 microcontroller via the SPI communications bus. The Supervisor directs the MC9S08 and thereby controls the image sensor operation. The Supervisor may command the camera to take both a back-ground frame (no illumination) followed immediately by an illuminated frame or simply one or the other types of frames. The image sensor data signals are connected to the DSP Video Port where images are acquired at a rate of 24 or 48 MegaPixels/sec. The full image can be acquired at a 48 MegaPixels/sec rate in-order to fi nd the target at high speed then the image sensor can be switched to the 24 MegaPixel/sec rate for precise image processing at lower image noise levels. The on-board controller can also monitor various functions of the image sensor, temperature, image frame pixel count and power supply voltages to ensure proper opera-tion. The image sensor can be commanded by the on board controller to generate an overlay test pattern. The DSP can analyze this test image to evaluate the image sensor functional integrity. Any failures or vari-ances from nominal will be reported by the Camera module controller to the Supervisor on the Main board by the inter-module SPI communications interface.

STROBE/RADIO MODULE

The Strobe/Radio module performs two independent functions; image illumination (strobe) and Bluetooth communications. Each function has a dedicated on-board Freescale MC9S08 low power microcontroller for independent operation. Image illumination is performed by two strings of six each, high effi ciency, high output Infrared LEDs. Two constant current power supplies can instantaneously deliver 300mAs of current to each string independently for a maximum strobe duration of 10 milliseconds. In normal operation, only one string of LEDs is required for a much shorter duration than 10 milliseconds, therefore each string can be used alter-nately thereby increasing the lifetime of each string. In addition, failure of an LED or a string power supply will only limit the use of the pod, not render the pod totally unusable. An MC9S08 microcontroller communicates with the Supervisor ARM microcontroller via the SPI bus to setup and control image illumination. The strobe signal from the Camera board is used to synchronize image illumination with the image sensor exposure duration. In addition, a Class 1 Bluetooth module with an external Centurion D-Puck high gain antenna is implemented on the Strobe/Radio module. A second MC9208 microcontroller bridges the standard Bluetooth HCI UART interface of the Bluetooth module with the custom highly reliable SPI communications bus used for all HawkEye inter-module communications. The Bluetooth module can be programmed to enter the Bluetooth defi ned Hold, Sniff or Park modes to conserve power during times of low usage. The strobe section controller monitors the various functions such as temperature, power supply voltages and LED current to ensure proper operation. The radio section controller monitors various functions such as radio interface communications and power supply voltages to ensure proper operation. Any failures or variances from nominal will be report-ed to the Supervisor on the Main board.

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CHAPTER 1 COMPONENT OVERVIEW

TOE SENSOR MODULE

Two toe sensors are used in the portable alignment system as a functional pair. One sensor is located in each pod. The sensor has a +/-7 degree cone of operation. The sensors are placed across from each other within each others cone of operation. The sensor reports the angle to the opposite sensor. This angle is associated with the rear cross toe. The toe sensor uses a CCD imager to measure the position of the oppo-site units toe LED. The CCD is exposed to light for a period of time called the exposure time. This number is reported in the diagnostic screen with units of sensor clocks periods. Maximum exposure is 12000. Two images are taken for each toe sample, one with the opposite LED on and the other with the opposite LED off. The two images are subtracted one from the other to remove light from the environment. The image of the LED that results from the subtraction is called a centroid. The position of the centroid in the sensor array is used to calculate the angle to the opposite sensor. The centroid is checked for intensity and shape. If no centroid is found, then the No Peak error is returned. If the centroid is distorted a Shape error is returned. If the centroid is too small, a Low Exposure error is returned. If the centroid is too large, a High Exposure error is returned. All of these errors can be seen in normal operation of the sensor. They represent a problem with an individual sensor sample and the sensor will automatically take action to correct the error. If these errors appear frequently or do not resolve themselves then they can be used to help diagnose toe faults. The toe sensor has special operating modes to deal with high ambient light. If the sensor is compensating for a high ambient light condition, the Sunlight condition is returned. If the CCD array is over exposed such that no image can be recorded, it is said to be in saturation. If a portion of the image is saturated, then a Clipped condition is returned.The sensor uses an IR communication link to check the optical path between the two sensors. If the IR com-munication link can not function the senor will report a Sensor blocked error. Within a pod the Toe sensor communicates using a SPI interface. If there is a fault in the Toe SPI communications within the pod a SPI Communication Fault is returned. Errors resulting from normal operation are reported in the CCD Error fl ag. When the toe sensor is fi rst turned on, it performs a self diagnostic. The results of this diagnostic are reported in the Board Error and Arm Error fl ags. In addition to the error fl ags, when in the diagnostic screen in the aligner live centroid images for both toe sensors are displayed. These can be used to visualize the er-ror states shown in the CCD error fl ag. On the extended diagnostics screen the board error and arm error fl ags can be viewed along with live voltage diagnostic data for the toe boards.

Toe Out Toe InZero Toe

Right Rear Reference

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CHAPTER 1 COMPONENT OVERVIEW

INCLINOMETER/ENCODER MODULE

The Inclinometer module implements a MEMS type inclinometer. This device was selected due to the ex-ceptional accuracy and repeatability specifi cations for a MEMS device. The MEMS type inclinometer is a two plane sensor giving us the ability to measure both camber and pod pitch in the same device. Two Texas Instruments MPS430 ultra low power microcontrollers each with a Sigma Delta 16 bit Analog to Digital converter, integrated temperature sensor and integrated SPI communications bus interface was selected to process and communicate the angle data from each inclinometer sensor outputs to the Main board via the inter-module SPI communications interface. In addition, the specifi c controller dedicated to the inclinometer pod pitch output can be made to operate in a pod wake-up mode. In this mode the inclinometer pitch output is constantly monitored for change. If a predetermined level of change should occur, signaling vibrations or activity around the vehicle, then the controller can toggle the SPI bus slave out data line (MISO) while the SPI interface is not active in-order to interrupt and wake the Main board Supervisor from sleep. During low or no activity (angle change) the Supervisor may successively reduce the frequency of the data acquisition cycles. Between cycles the Supervisor and other modules may be in a sleep state for long periods of time. The in-clinometer can detect very slight movements of the pod indicating potential activity around the vehicle. Upon detecting this movement, the controller can signal the Supervisor to wake and quickly begin data acquisition cycles.

A rotary potentiometer is used to encode the angle of the pod shaft relative to the wheel/wheel clamp assem-bly. A third and independent MPS430 that will convert the pot position into shaft angle and communicate the data to the Supervisor processor via the SPI bus. An optional shock or drop detection circuit utilizing a digital smart MEMs device can detect a free fall and sig-nal a fourth MPS430 to begin acquiring acceleration data from the smart MEMS device as well as record the time duration of the drop. In this way, a drop can be detected instantaneously, the time of fall and/or peak ac-celeration from the impact can calculated and used to evaluate the damage potential to the pod from the fall. Factory and fi eld calibration factors are calculated and stored in each MPS430 controller for each inclinom-eter output as well as the rotary potentiometer output. Each controller monitors various functions of the board including temperature and power supply voltages to ensure operation. The MEMS inclinometer can be placed in a test mode that defl ects the internal micromachined silicon beam by a constant amount. Evaluating this defl ection by measuring the angle output change can determine if the inclinometer is defective or out of cali-brations. Any failures or variances from nominal will be reported to the Supervisor on the Main board.

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