White Paper: Eaton VORAD Collision Warning System
Operation of the Eaton VORAD Collision Warning System and Analysis of the Recorded Data
David Danaher, P.E., Jeff Ball, Ph.D., P.E., Trevor Buss, P.E., and Mark Kittel, P.E 6-14-12ABSTRACT The Eaton VORAD Collision Warning System is utilized by many commercial trucking companies as a driver’s aid to improve vehicle and driver safety. The system is equipped with forward and side radar sensors that detect the presence and movements of vehicles around the truck and to alert the driver of other vehicles’ proximity. When the sensors detect that the host vehicle is closing on a vehicle ahead at a rate beyond a pre-determined threshold, or that a nearby vehicle is located in a position that may be hazardous, the system warns the driver visually and audibly. The system also monitors parameters of the vehicle on which it is installed, such as the vehicle speed and turn rate, as well as the status of vehicle systems and controls. The monitored data can be captured and recorded by the VORAD system and can be extracted in the event that the vehicle is involved in an accident. The recorded data can be used in accident reconstruction to show the movement and speed of the host vehicle as well as the position and speeds of other vehicles relative to the host vehicle prior to the incident. This paper will discuss the operation of the VORAD system, including the installation of the system, the configuration of the CPU, and the sources from which data is obtained for the various recorded parameters, as well as the analysis and interpretation of the recorded data. INTRODUCTION The Eaton VORAD EVT-300 Collision Warning System is designed to assist the driver in detecting potential hazards, and also to reduce the likelihood of accidents and promote safer driving habits. The EVT-300 Collision Warning System is a high frequency radar system that can be fitted to most commercial vehicles. The EVT-300 is designed to detect potential hazards in the surrounding area of the vehicle and to warn the driver of those potential hazards. The system can track multiple vehicles at one time that are traveling in front or to the side of the host vehicle. If there is a potential hazard detected by the EVT-300, the system warns the driver by means of a small display mounted in the driver compartment which emits a series of lights and audible sounds in intervals from three seconds to a half-second to warn the driver prior to an accident occurring . DESCRIPTION OF COMPONENTS The EVT-300 is an aftermarket unit that is designed to be installed on a variety of commercial trucks and to interface with the base ECM. The system consists of an antenna assembly (forward looking radar), optional side sensor, central processing unit (CPU) with gyroscope, driver display, optional side sensor display and wiring harness. ANTENNA ASSEMBLY – The antenna assembly mounts to the front of the truck. It transmits and receives low power, high frequency radar signals. The radar signal has a 12 degree beam width and has a range up to 350 feet. The system can monitor 20 objects simultaneously, regardless if the objects are moving or not. The signals are transmitted from the antenna assembly away from the front of the truck and towards an object within the radars range. The radar signal then reflects off the object and is received back by the antenna assembly. The system uses the Doppler effect to determine relative speeds of other vehicles compared to the speed of the host vehicle. The antenna assembly then compares the difference between the transmitted signal and the received signal, and processes the data. The data is then digitally converted and sent to the central processing unit for further evaluation . The total system has an accuracy of: range 5% ±3 feet, velocity 1% ±0.2 mph, azimuth ±0.2 degrees . CENTRAL PROCESSING UNIT – The central processing unit (CPU) is essentially the brain of the unit in conjunction with the forward and side sensors. The CPU collects the data from the attached VORAD sensors (forward antenna, side sensor and internal gyroscope) as well as from the host vehicle’s ECM (vehicle speed, brake signal, and turn signals). The CPU analyzes the data to determine if there is a potential hazard for the driver and sends the appropriate signal to the driver display unit if necessary. The CPU also has an optional function that can be used for accident reconstruction that records data in the CPU memory for several minutes prior to an accident. The data can then be downloaded by Eaton VORAD at their facilities . The memory feature will be discussed in further detail later in this paper. GYROSCOPE – The gyroscope is located in the CPU and monitors the rate at which the vehicle is turning. The gyroscope is designed to measure the orientation of the vehicle based on the principles of angular momentum . DRIVER DISPLAY UNIT – The driver display unit (DDU) has two control knobs, one for the range and the other for the volume, three colored (yellow, orange, red) warning lights, a green power light, a red system failure light and a light sensor. The unit is also equipped with a speaker that produces audible tones to alert or warn the driver if the vehicle is near an approaching object. The unit may also have a slot to allow an optional Driver Identification Card . SIDE SENSOR – The side sensor is similar to the antenna assembly in that it transmits a radar signal. The sensor can detect objects from two to ten feet from the side of the truck, typically on the right. The data is then sent to the CPU for processing which then determines if any lights or audible warnings are necessary for the driver . SIDE SENSOR DISPLAY – The side sensor display has a yellow “no vehicle detected” indicator light and a red “vehicle detected” light. The display also has an ambient light sensor to allow the automatic adjustment of the lights in various ambient lighting conditions . WIRING HARNESS – The wiring harness is used to connect all the external inputs and sensors such as the CPU, antenna assembly, driver display unit, side sensor and side sensor display. VEHICLE DATA ACQUISITION The VORAD EVT 300 system obtains accident reconstruction related data from the host vehicle for three vehicle parameters: host vehicle speed, brake status, and turn signal activity. The host vehicle speed data is produced independently of the VOARAD system; the VORAD system simply monitors and records the speed data produced by the vehicle. This data can be acquired by wiring directly from the vehicle’s speedometer circuitry or from the vehicle’s central data bus. In either case, the source of the vehicle speed data is the same as the data that is utilized by the vehicle’s speedometer. In typical modern heavy truck installations, speedometer data is typically produced by a system that monitors the electronic pulses from a sensor reading a toothed wheel that is incorporated into the vehicle’s drive train. The speedometer system is calibrated to the number of pulses per revolution of the sensing wheel, the number of revolutions per mile of the drive wheels on the truck and the necessary gear ratios. Therefore, the accuracy and precision of the host vehicle speed data reported by the VORAD system is entirely dependent on that of the vehicle’s own speed monitoring system. Changes to vehicle equipment, such as non-OEM wheels and tires, may affect the calibration of the speed monitoring system, and situational occurrences such as locked or semi-locked drive axles during braking may affect the accuracy of the data. Therefore, considerations should be made when interpreting the speed data reported by the VORAD system. The data available regarding the status of the host vehicle’s brakes is again acquired either through a direct connection to the vehicle’s brake light circuitry, or through the central data bus. The EVT-300 system monitors and records only the binary status of the brake system; i.e. whether the brakes are on or off. This data corresponds with the activation of the host vehicle’s brake lights. Therefore, while the system will record information as to when the vehicles brakes are applied, it does not monitor the level at which the driver applies the brakes or the level of depression of the brake pedal. The EVT-300 system does report on the level of deceleration of the vehicle by way of a thin or thick line in the data plots that can be produced by the system, but this information is obtained by derivation of the speed data and not from the brake circuitry. The VORAD system monitors turn signal activity directly from the turn signal light bulb circuitry. Similar to the brake system, the EVT-300 only monitors the binary status of the turn signal circuitry. In some installations with a single side radar sensor mounted on the right, the VORAD system may only monitor the status of the right-side turn signal circuitry. Otherwise, the system records turn signal activation when either the right or left turn signal or the four-way emergency flashers are activated, and it does not distinguish which type of activation is occurring. The source of the recorded turn signal activity can be determined through review of the CPU configuration and inspection of the system installation. RECORDED DATA One of the most valuable features of the Eaton VORAD system is its ability to provide a commercial truck driver with additional information and warnings that enhance driver awareness and ultimately highway safety. In addition to this, the VORAD system also has the ability to record and store the data that it monitors. This information can be invaluable to an accident reconstruction investigator should the vehicle be involved in an accident. The VORAD system records data from the truck on which it is installed that is typical of other Event Data Records that are increasingly common on heavy trucks today, such as speed, control status and fleet maintenance information. Additionally, the VORAD system also has the ability to record information regarding other vehicles in the vicinity of the host vehicle that may be involved in the accident with the truck through the use of its radar sensor system. This additional benefit is unique relative to typical truck EDR’s, and may provided evidence to an accident reconstructionist that would otherwise be unavailable. SYSTEM MEMORY – The EVT-300 system is capable of recording between approximately 2 and 10 minutes of data. The total amount of recorded time is dependent on the number of objects that the system is detecting during the time period. In other words, as more objects are detected by the system, more memory is required for each time step, and the total duration of recorded time is reduced. The memory of the system acts as a rolling buffer; as the truck continues to drive, the oldest data is overwritten by the newest data. If the truck stops, the most recent data remains in the system. If it is deemed necessary (as in the event of a motor vehicle accident) the CPU memory can be frozen such that it will not be overwritten if the truck continues to drive. The memory is frozen by pushing the “Range” button on the driver display unit for approximately 5 seconds. The stored memory is confirmed by a green light on the display unit blinking 8 times. Furthermore, the system contains two memory “sections” in which it can record data. When the first memory section is frozen, data is then recorded in the second memory section. If the truck has not been driven after the first memory section has been frozen, no data will be present in the second memory section. It should be noted that in some versions of the VORAD system, the frozen memory section may be cleared if the data has not been extracted within 30 days. This will only occur if the truck has been driven or if power is supplied to the unit after the memory is frozen. The CPU contains a battery back-up system that allows the recorded data to be retained for approximately 5 years without power supplied to the CPU. In the event that the VORAD memory has been frozen, the VORAD CPU can be removed from the vehicle and sent to Eaton VORAD for extraction. This process involves transferring the CPU data to a separate memory card, and then reading the extracted data using proprietary software developed by Eaton. Once the data has been transferred from the CPU to the memory card, it is automatically erased from the CPU. An important step in the extraction processes involves correlating the recorded time and date on the CPU data to the actual time of the extraction. This is done so that any discrepancy in the CPU time versus the actual time of extraction can be accounted for to determine the specific time of occurrences that may be shown in the data reports. DATA REPORTS – After the data has been extracted by Eaton, the information is then presented in the form of a Basic Data Report, available from Eaton VORAD for a fee. The Basic Data Report generally includes approximately 5 minutes of data, typically correlated to the likely event of interest, such as a clear hard braking occurrence in the data. The Basic Data Report includes a series of graphical plots that depict the recorded parameters in a visual form, as well as a section that describes data presented in the graphical plots (although only in a generic sense and not specific to the subject data). AR Data Header – The AR Data header “provides information about the VORAD model, software type, vehicle ID and other pertinent system information.” This data also contains information about the contents and status of the system memory. For example, the second line of the AR Data header indicates whether the CPU memory was frozen by displaying a “0” for no or a “1” for yes. There are 4 lines in the AR Data header that begin with “cr:” The first two lines refer to the first memory section, and the third and fourth lines refer to the second memory section. If no data was recorded in the second memory section, the “count” value (denoted “cnt”) will read 0. CPU Configuration – The CPU Configuration section of the data report contains information regarding the settings for the system, the installation of the system, and certain “checks” in place to confirm the validity of the system configuration. The data validity checks are located in the first two lines of the configuration table. The first is denoted “S,CERROR.” A value of 1000 following this indicates that the system performed a successful reading of the CPU configuration. The next check is denoted “S,PERROR” and for this, a value of F indicates that no single value of the CPU configuration was read incorrectly. The remainder of the CPU configuration parameters are presented by the parameter name, followed by the value to which the parameter is set, and then a description of either the value that is indicated, or of the binary logic that applies to the parameter. The details of the CPU Configuration parameters are shown in Appendix A. Graphical Plots –The Basic Data Report contains graphical plots of the data that has been extracted from the VORAD CPU. A detailed description of the data that is presented in the graphs is included with the Data Reports; therefore this paper will provide a brief overview and focus on details that are not discussed in the provided material. There are 9 parameters represented on the graphical plots:
- Object Distance (feet) – This plot shows the distance from the radar on the host vehicle to the various objects that the system detects. The system uses different colors on the plot to differentiate between the various objects that the system picks up. However, there may be occasions in which the object detection signal is weak or is lost for a brief period, and when the system re-establishes a signal for the object, it may assign a new color to the object when in fact it is the same object that was previously depicted. This occurrence can be recognized by examining the trend of the line shown in the graph.
- Cross Range (feet) – This plot shows the lateral distance of the detected objects relative to the projected centerline of the host vehicle. The colors shown on this plot correspond with those of the Object Distance plot. It is noted in the provided description of this graph that this data is not adjusted relative to the turn rate data for the host vehicle. Therefore the data shown in this plot will be affected when the vehicles are driving in a curve. Although this is how the data is depicted in the graph, the CPU does account for the road curvature when issuing driver alerts.
- Object Speed (miles per hour) – This plot shows the ground speed of the objects being detected by the radar, again with colors that correspond with those in the Object Distance plot. This data is calculated based on the recorded speed of the host vehicle and the relative speed of the detected objects as measured by the radar.
- Host Speed (miles per hour) – This plot shows the ground speed of the host vehicle. The actual speed data points are depicted as dots, and a line is fit to these data points. Data values for the host speed are recorded when there is a change in the speed of the vehicle.
- Host Turn Rate (degrees per second) – This plot shows the rate of change of the directional heading of the host vehicle. It is important to recognize that this plot does not depict the vehicle’s heading. The actual vehicle heading is a function of the turn rate and the speed that the vehicle is traveling. The color of the turn rate plots corresponds to calculated lateral acceleration thresholds that the vehicle reached.
- Brake Status – This plot depicts a line that shows when the brakes are activated. The thickness of this line is determined by the rate of change of the speed data that is acquired from the vehicle. A thicker line indicates a greater rate of deceleration. The thickness of the line depicted is therefore not a direct measure of how hard the brakes are applied.
- Alarm Status – The type of alarm that is activated is depicted by the coded color and thickness of the line. A thicker line does not indicate an increase in the volume of the alarm, although the thicker lines depict alarm levels that correspond to a greater level of emergency.
- Side Sensor Status – Displays when an object is detected by the side sensor. The width of the line on the side sensor plot indicates whether the first or second (or both) side sensor has been activated. A narrow line indicates side sensor #1, a medium line indicates side sensor #2, and a thick line indicates that both side sensors are detecting an object. It cannot be determined from the data if a single vehicle or multiple vehicles are being detected by the side sensors.
- Turn Signal Status – Displays when the host vehicle turn signal is activated. If only the right side turn signal is connected to the unit, the system will not record an activation when the left turn signal is activated. If both the left and right turn signals are connected to the unit, one cannot determine which direction of turn signal is activated from the data.