DBS_Test_Procedure_JUNE2012.pdf

DYNAMIC BRAKE SUPPORT SYSTEM

PERFORMANCE EVALUATION

June 2012

Office of Vehicle Safety Research 1200 New Jersey Avenue, SE

Washington, DC 20590

Dynamic Brake Support System Performance Evaluation

DYNAMIC BRAKE SUPPORT PERFORMANCE EVALUTION

TABLE OF CONTENTS

1.0 PURPOSE AND APPLICATION

2.0 GENERAL REQUIREMENTS

3.0 SECURITY

4.0 GOOD HOUSEKEEPING

5.0 TEST SCHEDULING AND MONITORING

6.0 TEST DATA DISPOSITION

7.0 VEHICLES AND EQUIPMENT (GFP)

8.0 INSTRUMENTATION AND CALIBRATION

9.0 PHOTOGRAPHIC DOCUMENTATION

10.0 DEFINITIONS

11.0 PRETEST AND FACILITY REQUIREMENTS

12.0 TEST EXECUTION AND TEST REQUIREMENTS

13.0 POST TEST REQUIREMENTS

14.0 REPORTS

15.0 DATA SHEETS

1.0 PURPOSE AND APPLICATION

This laboratory test procedure provides specifications for objectively quantifying the performance of a Dynamic Brake Support (DBS) system installed in a passenger vehicle with a gross vehicle weight rating (GVWR) of under 10,000 pounds. Current DBS technology is dependent on RADAR, LIDAR, and/or vision based sensors capable of detecting traffic.

Although it is impossible to predict what sensing technologies could be used in future DBS systems, it is believed that with minor modifications to the test setup, systems with alternative sensing methods may be also be evaluated.

The requirements of this indicant test procedure must be strictly adhered to. The Contractor's in-house test procedure must have NHTSA approval prior to conducting the first test of a particular fiscal year program. The Contractor's test procedure cannot deviate in any way from the NHTSA procedure without the prior approval of the NHTSA COTR.

2.0 GENERAL REQUIREMENTS

This test evaluates the ability of a DBS system to detect, and respond to via automatic supplementation to the vehicle’s foundation brake system, a hazard in the forward path of the vehicle being evaluated. Two driving scenarios are utilized to assess DBS performance. In the first test, a subject vehicle (SV) approaches a stopped principal other vehicle (POV) in the same lane of travel. The second test consists of the SV, traveling at a constant speed, approaching a slower POV moving at a constant speed. In both tests, the POV is a strikeable object with the characteristics of a compact passenger car. The specific attributes of the POV are described in S7.4.

3.0 SECURITY

The Contractor shall provide appropriate security measures to protect test vehicles and equipment during the entire test program, and shall be responsible for all equipment removed from test vehicles before and after the test. Vehicle equipment thefts or act of vandalism must be reported to NHTSA authorities immediately. Under no circumstances shall any vehicle components be removed during a visitor inspection unless authorized by an Office of Crash Avoidance Standards (OCAS) representative. All data developed from the test program shall be protected.

3.1 Rules for Contractors

1. No vehicle manufacturer's representative(s), or anyone other than the Contractor's personnel working on the Contracts and NHTSA personnel, shall be allowed to inspect NHTSA vehicles or witness vehicle preparations and/or testing without prior permission of the OCAS. Such permission can never be assumed.

1. All communications with vehicle manufacturers shall be referred to the OCAS, and at no time shall the Contractor release test data without the permission of the OCAS.

2. Unless otherwise specified, the vehicle manufacturer's representatives shall only be authorized to visit the Contractor's test facility on the day that the test is scheduled, and the representatives must be escorted by NHTSA and/or Contractor personnel.

3. Test vehicle inspection by the vehicle manufacturer's representative(s) shall be limited to 30 minutes prior to the start of vehicle test. Post-test inspection shall be limited to one (1) hour after Contractor personnel have completed their test tasks.

4. Photographs and videos of the test vehicle, associated test equipment and test event shall be allowed. However, test personnel shall not be included in any photographic coverage, and video data collection of vehicle preparation must be approved by the OCAS. The Contractor's personnel shall not respond to any questions from the manufacturer's representatives regarding this test program. All questions shall be referred to the COTR, an OCAS representative present at the test site, or to the OCAS.

5. The Contractor shall permit public access to and inspection of the test vehicles and related data during the times specified by the NHTSA COTR. NHTSA shall advise interested parties that such access and inspection shall be limited to a specified day, specified hours, and require prior approval from the OCAS. The Contractor shall refer all visit requests from vehicle manufacturer's representatives and consumers to the OCAS.

This service shall be included as an incidental part of the test program and will not result in any additional cost to the NHTSA. The Contractor shall make their own arrangements with interested parties for expenses incurred beyond providing access and inspection services. All inquiries by manufacturers concerning the test program (vehicle, procedures, data, etc.) shall be directed to OCAS representatives.

4.0 GOOD HOUSEKEEPING

The Contractor shall maintain the entire test area, vehicle pre-test preparation facility, instrumentation building, and equipment configuration and performance verification test laboratory in a clean, organized, and painted condition. All test instrumentation must be setup in an orderly manner consistent with good engineering practices.

5.0 TEST SCHEDULING AND MONITORING

The Contractor shall commence testing within four (4) weeks after receipt of the first test vehicle. Subsequent tests will be conducted, if requested, at a minimum of one (1) vehicle test per week. The NHTSA COTR will make adjustments to the test schedule in cases of unusual circumstances such as inclement weather or difficulty experienced in the procurement of a particular vehicle make and model. All testing shall be coordinated to allow monitoring by the

COTR.

6.0 TEST DATA DISPOSITION

The Contractor shall make all test data available within two hours after the test event if so requested by NHTSA personnel. Under no circumstances shall this preliminary data be furnished to non-NHTSA personnel. The Contractor shall analyze the preliminary test results as directed by the COTR.

6.1 Test Data and Final Hardcopy

The Contractor shall deliver to the OCAS the final data, digital printouts, and plots highlighting key data traces on a CD or DVD within one (1) week after the test.

6.2 Test Report

6.2.1 Report Content

This test report shall include all of the items shown in the Sample Test Report. The text and data sheet portion of the test report shall be in Microsoft Word format. Digital pictures shall be in JPEG format. The Contractor shall submit two (2) CDs or DVDs and one (1) paper copy of the test report to the following address:

U. S. Department of Transportation National Highway Traffic Safety Administration Office of Crash Avoidance Standards (NVS-120) 1200 New Jersey Avenue, SE, Room W43-478

6.2.2 Report Submission

All final test reports shall be submitted to the above listed NHTSA office within four (4) weeks from the date of the vehicle test.

6.3 Test Video

The OCAS shall receive one (1) copy of the color video for each test, and the copies shall be mailed directly to the OCAS within four (4) weeks of the vehicle test. The master print for each of the test videos shall be retained by the Contractor, but will be made available to the OCAS upon request. See Section 9.1 for a description of the video to be taken during CIB test conduct.

6.4 Data Loss

6.4.1 Conditions for Retest

The test vehicle shall be instrumented in order to obtain data needed for the test program. An invalid test is one which does not conform precisely to all requirements/specifications of the laboratory test procedure and Statement of Work applicable to the test.

The NHTSA Contracting Officer (CO) is the only NHTSA official authorized to notify the Contractor that a retest is required.

No test report is required for any test which is determined to be invalid unless NHTSA specifically decides to require the Contractor to submit such report. Invalidated test reports will not be publicly released.

RETEST CONDITIONS

Failure of the Contractor to obtain the specified data and to maintain acceptable limits of test parameters in the manner outlined in this test procedure shall require a retest at the expense of the Contractor. The provisions of this paragraph apply to, but are not limited to, the Contractor maintaining proper speed tolerance, vehicle performance, and test data acquisition, reduction, and processing.

The Contractor shall also be responsible for obtaining usable data from all primary channels from instrumentation placed in each vehicle. Failure to produce such data shall also be at the expense of the Contractor and shall include vehicle repair or replacement and retest unless the Office of Crash Avoidance Standards determines that the data loss occurred through conditions beyond reasonable and foreseeable control of the Contractor. Should it become necessary for the Contractor to procure another test vehicle, it must have identical equipment and options as the original vehicle. The retested vehicle shall be retained without fee by the testing facility until its disposal is authorized by the COTR.

6.4.2 Conditions for Partial Payment

The Contractor shall exercise reasonable and foreseeable control to insure that no data is lost or rendered useless. If some non-critical data (such as camera failure) and critical data (such as vehicle position data) are not obtained for the test and the test is accepted by the Agency, the Agency will not pay for the missing or lost data.

6.5 Data Retention by Contractor

The Contractor shall retain at no extra cost to the NHTSA, reproducible copies of all data (analog and digital), videos, and still photograph negatives or electronic files for a period of one

(1) year after test completion.

6.6 Data Availability to the Public

The Contractor shall provide interested parties with copies of test report, test data on a CD or DVD, test video, and/or test still photographs, at a reasonable cost to the purchaser, but only after the OCAS representative has advised the Contractor that the results of that particular test have been released to the public by the NHTSA.

6.7 Indicant Failure Notification

Any indication of a “test failure” shall be communicated by telephone to the COTR within 24 hours of the test.

NOTE: In the event of a failure, a post-test calibration check of some critically sensitive test equipment and instrumentation may be required for verification of accuracy. The necessity for the calibration shall be at the COTR's discretion and shall be performed without additional cost.

7.0 VEHICLES AND EQUIPMENT

7.1 Acceptance of Test Vehicles

The Contractor has the responsibility of accepting leased or NHTSA-provided test vehicles from new car dealers, leasing companies, or vehicle transporters. In all instances, the Contractor acts in the NHTSA’s behalf when signing an acceptance of test vehicles. The Contractor must check to verify the following:

1. The equipment necessary to support DBS functionally is present on the test vehicle

2. All options listed on the “window sticker” are present on the test vehicle.

3. Tires and wheel rims are the same as listed.

4. There are no dents or other interior or exterior flaws.

5. The vehicle has been properly prepared and is in running condition.

6. Verify that spare tire, jack, lug wrench, and tool kit (if applicable) is located in the vehicle cargo area.

The Contractor shall check for damage that may have occurred during transit or prior use. The COTR is to be notified of any damage prior to preparation of the vehicle for testing.

7.2 Notification of COTR

The COTR must be notified within 24 hours after a vehicle has been delivered.

7.3 Government Furnished Equipment (GFE)

No Government Furnished Equipment will be available or provided for the tests described in this document.

7.4 Principal Other Vehicle (POV)

The Contractor shall use a strikeable object with the characteristics of a compact passenger car for use as the POV. This is intended to maximize the ability of the SV to detect the POV in the most realistic manner possible without compromising SV driver safety and minimizing the potential for SV damage. Specifically, the strikeable object must possess the following attributes:

1. Accurate physical characteristics (e.g., visual, dimensional, etc.) when approached with a

SV heading angle of ±5 degrees

2. A RADAR return signature representative of the rear of a high volume compact passenger car equipped with a United States-specification license plate when approached with a SV heading angle of ±5 degrees

3. Remain consistently shaped (e.g., visually, dimensionally, internally, and from a RADAR sensing perspective) within each test series, and throughout the three series testing timeline.

4. Resistant to damage resulting from repeated SV-to-POV impacts

5. Impose minimal to no damage to the SV, even in the event of multiple impacts.

The Contractor shall present documentation that objectively qualifies how the POV used to perform the tests described in S12.3 and S12.4 satisfied the requirements of S7.4.1 through S7.4.5.

7.5 Principal Other Vehicle (POV) Moving Platform

For the Slower POV Moving tests described in S12.4, the POV is moved at one of two constant speeds. To eliminate abrasion between the POV and the test surface during these trials, a moving platform shall be utilized.

To reduce the potential for the POV moving platform to confound CIB RADAR sensor operation during test conduct, the platform shall not be fabricated from metal, or have a metallic frame.

To reduce the potential for the moving platform to confound CIB LIDAR sensor or camera operation during test conduct the top surface of the moving platform shall be low-gloss (i.e., to reduce glare when performing tests in direct sunlight, etc.).

Note: The POV moving platform presently used by NHTSA is measures 12 x 8 ft (3.7 x 2.4 m), and was constructed from two layers of 1/4-in plywood. To reduce wear, three 3-in (76.2 mm) ultra-high molecular weight (UHMW) plastic strips are secured along the length of the platform bottom; one close to each longitudinal edge, one near the center. To accommodate the POV lateral restraint track specified in S7.6, it is anticipated that the single center strip will be replaced by two strips of similar dimensions, spaced approximately 1/8-in (3.2 mm) wider than the 4-in (102 mm) track. The center of this “gap” will be the centerline of the platform.

Use of 3/16-in (4.8 mm) wide plastic zip-ties to secure the POV to the moving platform is recommended. This securing method allows the POV to easily break away from the attachment points in the event SV-to-POV contact occurs.

The front of the platform shall be connected to a tensile load cell attached to the rear of a tow vehicle with a low-creep, abrasion-resistant rope (e.g., 3/8-in (9.5 mm) diameter braided Vectran or equivalent). Due to the potential for damage to the SV during test conduct, use of tow line manufactured from braided steel cable is not recommended. Use of 1/4-in (6.4 mm) wide plastic zip-tie “fuses” to attach the tow rope to the moving platform and to the POV tow vehicle is recommended.

7.6 Principal Other Vehicle (POV) Lateral Restraint Track

To allow the POV tow vehicle to pull the POV in a straight line without affecting the lateral orientation between the two, a lateral restraint track shall be used during conduct of the Slower POV tests described in S12.4.

Note: Detailed POV lateral restrain track specifications are presently under development, and may ultimately be provided in the Appendix of this document. Conceptually, this straight track is envisioned to be a single 1000 ft (305 m) long plastic strip secured to the test surface in the center of the travel lane. This strip will likely have a rectangular cross section of approximately

0.75 x 4-in (19 x 102 mm). The bottom of the POV moving platform would have a similarly – sized “notch” that would allow the platform to interface with the track.

7.7 Principal Other Vehicle (POV) Tow Vehicle

During conduct of the Slower Moving POV tests described in S12.4, a tow vehicle shall be used to bring the POV and POV Moving Platform combination to the desired test speed. This mitigates many of the logistic issues associated with having the POV being self-propelled.

However, since the POV does not contain any instrumentation, its state must be derived by translating known parameters of the POV tow vehicle back to the POV. The accuracy of this translation strongly depends maintaining a known longitudinal and lateral distance between the POV and POV tow vehicle. For the sake of driver safety, the distance between the POV and

POV tow vehicle shall nominally be 100 ft (31 m), however the actual distance shall be measured and recorded in S8.3.10.

8.0 INSTRUMENTATION AND CALIBRATION

8.1 Required Test Equipment

1. Portable tire pressure gauge with an operating pressure of at least 100 psi (700 kPa), graduated increments of 0.1 psi (1 kPa), and an accuracy of at least ±2.0% of the applied pressure.

2. Global Positioning System (GPS) equipment capable of providing position data (latitude and longitude) with at least 1.6 in (4.1 cm) static accuracy, 3.9 in (10 cm) dynamic accuracy, and update at a rate of at least 10 Hz. Use of a GPS system that provides real-time SV-to-POV headway data to the SV driver is recommended (e.g., via a windshield-mounted display)

A. For the Stopped POV tests described in S12.3, one GPS rover (a receiver) shall be installed in the SV. The rear-most location of the POV shall be surveyed and represented by a fixed point. For these tests, SV-to-POV headway is defined as the longitudinal distance from the front most location of the SV to the fixed point.

B. For the Slower Moving POV tests described in S12.4, one GPS rover shall be installed in the SV and one in the POV tow vehicle. For this test, SV-to-POV headway is defined as the longitudinal distance from the front most location of the SV to the rear of the POV.

3. A data acquisition system (DAS) shall be installed in the SV. The DAS shall record GPS data from the SV and POV tow vehicle, SV yaw rate and longitudinal acceleration, and POV tow rope tension. Alternatively, POV rope tension may be recorded by a DAS installed in the POV if the respective data files are synchronized with those collected by the SV DAS.

4. All data shall be sampled at 100 Hz.

5. Signal conditioning shall consist of amplification and digitizing. Amplifier gains shall be selected to maximize the signal-to-noise ratio of the digitized data. Filtering of the data as it is collected is not necessary. However, if a filter is applied to incoming data, it shall be of a low-pass Butterworth specification with nominal cutoff frequencies selected to prevent aliasing.

8.2 Calibration

Before the Contractor initiates the test program, a test instrumentation calibration system must be implemented and maintained in accordance with established calibration practices.

Guidelines for setting up and maintaining such calibration systems are described in MIL-C-45662A, “Calibration System Requirements.” The calibration system shall be set up and maintained as follows:

1. Standards (e.g., reference equipment) for calibrating the measuring instruments and test equipment will be stored and used under appropriate environmental conditions to assure their accuracy and stability.

2. All measuring instruments, test equipment, and test standards shall be calibrated by the Contractor, or a commercial facility, against a higher order standard at periodic intervals not exceeding twelve (12) months. Records, showing the calibration traceability to the National Institute of Standards and Technology (NIST), shall be maintained for all measuring and test equipment. The calibration frequency can be increased if deemed necessary by NHTSA.

3. All measuring instruments, test equipment, and test standards will be labeled with the following information:

A. Date of calibration

B. Date of next scheduled calibration

C. Name of the organization and the technician who calibrated the equipment

D. A written calibration procedure shall be provided by the Contractor which includes as a minimum the following information for all measurement and test equipment:

i. Type of equipment, manufacturer model number, etc.

ii. Measurement range

iii. Accuracy

iv. Calibration interval

v. Type of standard used to calibrate the equipment (calibration traceability of the standard must be evident)

vi. The actual procedures and forms used to perform the calibrations.

4. Records of calibration for all test instrumentation shall be kept by the Contractor in a manner that assures the maintenance of established calibration schedules. All such records shall be readily available for inspection when requested by the COTR and shall be included in the final test report. The calibration system will need the acceptance of the COTR before testing commences.

5. Test equipment shall receive a pre- and post-test zero and calibration checks. These checks shall be recorded by the test technician(s) and submitted with the final report.

NOTE: If review of these data provided in S6.1 reveals questionable or inconsistent results, additional calibration checks of some critically sensitive test equipment and instrumentation may be required for verification of accuracy. The necessity for the calibration will be at the COTR's discretion and will be performed without additional cost to the OCAS.

8.3 Test Vehicle Measurement and Preparation

1. All sensors used by the SV CIB system, and any part of the vehicle immediately ahead of them (e.g., plastic trim, the windshield, etc), shall be free of debris or obstructions.

2. The SV airbags shall be disabled using instructions provided by the OCAS.

3. Use of adhesive-backed temporary paint protection applied to the front bumper, front fenders, hood, A-pillars, and the front face of the side mirrors of the SV is highly recommended. However, the protective material must not obstruct any sensor providing data to the DBS system.

4. The SV tires shall be inflated to the recommended cold inflation pressure specified on the vehicle placard or optional tire inflation pressure label.

5. All non-consumable fluids must be at 100 percent capacity for the SV. SV Fuel must be maintained at least 75 percent capacity during the testing.

6. The SV shall be loaded with one driver and all required equipment during the testing.

Where possible, the equipment shall be placed on the passenger side of the vehicle.

Inclusion of an in-vehicle experimenter to assist the SV driver with test conduct (e.g., data acquisition, completion of logs, etc.) is permitted. Where possible, the in-vehicle experimenter shall be seated in the first seating position behind the driver’s seat.

7. The centerline of the SV, POV, and POV tow vehicle shall be measured and recorded.

8. The lateral, longitudinal, and vertical positions of the GPS antennas installed on the SV and POV tow vehicle shall be measured and recorded.

9. For the SV, the longitudinal distance from the GPS antenna to the front-most position of the front bumper shall be measured and recorded.

10. With the POV tow rope tension at the magnitude determined in S12.1.1.3, the longitudinal distance from the GPS antenna of the POV tow vehicle to the rear-most position of the POV rear bumper shall be measured and recorded.

9.0 PHOTOGRAPHIC DOCUMENTATION

Each vehicle shall be documented with color still pictures. Each test trial shall be documented using a color video camera. To facilitate visual analyses, light glare and shadows must be minimal.

9.1 Cameras Required

CAMERA 1: Real-time video inside of the SV.

CAMERA 2: Real-time video camera to one side of the most significant even area of the test.

CAMERA 3: A still camera to document the vehicle.

9.2 Informational Placards

Vehicle identification placards shall be positioned so that at least one placard will be visible in the field-of-view for at least one video camera. The following information will be shown:

1. Vehicle's NHTSA Number

2. The words “OCAS DYNAMIC BRAKE SUPPORT TEST”

3. Date of test

4. Name of contract laboratory

5. Vehicle year, make, and model

9.3 Test Video Title and Ending

Test video shall include the following title frames:

1. “The following Dynamic Brake Support test was conducted under contract with the

National Highway Traffic Safety Administration by (name and location of test laboratory)”

2. OCAS DYNAMIC BRAKE SUPPORT TEST

3. TEST VEHICLE MODEL YEAR, MAKE, AND MODEL

4. NHTSA No. CXXXXX

5. DATE OF EVENT

6. CONTRACT NO.: DTNH22-XX-X-XXXXX

7. The ending frame shall state “THE END”

9.4 Film Editing

The film shall be edited in the following sequence below. Any vehicle failures shall be completely documented.

1. Title

2. Pretest Coverage

3. Real Time Pan Coverage

4. Post test Coverage

5. “The End”

9.5 Still Photographs

The following still photographs (8 x 10 inch or 8.5 x 11 inch color prints properly focused for clear images) are required for the test:

1. Pretest, uninstrumented pictures of the SV (front, rear, and four three-quarter pictures)

2. Pretest, instrumented pictures of the SV, POV, and POV tow vehicle (front, rear, four three-quarter pictures, and pictures of the instrumentation)

3. SV tire placards

4. Window Sticker (i.e., Monroney label)

10.0 DEFINITIONS

Dynamic Brake Support (DBS) is a technology that actively increases the amount of braking provided to the driver during a rear-end crash avoidance maneuver. If the driver has applied force to the brake pedal, DBS uses forward-looking sensor data provided by technologies such as RADAR, LIDAR, video cameras, etc. to assess the potential for a rear-end crash. Should DBS ascertain a crash is likely (i.e., the sensor data indicate the driver has not applied enough braking to avoid the crash), DBS automatically intervenes. Although the manner in which DBS has been implemented differs among vehicle manufacturers, the objective of the interventions is largely the same: supplement the driver’s commanded brake input by increasing the output of the foundation brake system. In some situations, the increased brake force provided by DBS may allow the driver to avoid a crash. In other cases, DBS interventions mitigate crash severity.

10.1 System Purpose

DBS systems intervene in driving situations where a rear-end collision is expected to be unavoidable unless additional braking is realized. Since they are designed to occur so late in the pre-crash timeline, and the driver has already initiated crash avoidance braking, DBS systems are not required to alert the driver a DBS intervention has occurred. Although DBS may be provided in combination with an adaptive cruise control (ACC) system, use of any form of cruise control (i.e., conventional or ACC), to automatically control the SV speed is not permitted during test conduct.

10.2 System Attributes

1. Provides for continuous monitoring of vehicles in the forward pathway of the SV vehicle using sensing/communications technologies such as RADAR, LIDAR (laser), video cameras, etc., or any combination thereof.

2. The DBS system shall initialize, and be available to automatically supplement the SV brakes, when the vehicle is traveling ≥10 mph (≥16 km/h), and remain operational throughout the vehicle’s attainable speed range (up to Vmax).

3. There may be weather and/or infrastructure situations when the DBS system cannot detect vehicles in the forward pathway of the SV. DBS systems may also be limited in capability and/or accuracy due to other factors such as sensor blockage or interference, visibility conditions, roadway geometry, roadside clutter, etc. It is not the intention of the test procedures described in this document to simulate or accommodate these situations, as false, delayed, or missed warnings may occur.

10.3 Failure Mode Operation

If the DBS system is operating in a failure mode (e.g., the system is not operational due to environmental, mechanical, or software-related reasons), the system shall suppress DBS interventions and notify the driver of the failure condition.

10.4 Suppressed Operation During Test Conduct

Some DBS systems include control algorithms capable of delaying and/or suppressing system activation under certain real-world operating conditions. These algorithms are intended to minimize the likelihood of “false activations” (i.e., DBS interventions that occur when not necessary) or “undesired activations” (i.e., during times where an individual is actively driving, but operating their vehicle within a close proximity to another immediately in front of them).

In either case, the intent of DBS suppression is to avoid activations that violate the expectation of an attentive driver.

The tests described in this document are expected to be performed within the idealized confines of a test track with careful and deliberate inputs from the driver. As such, DBS system suppression is not expected to occur during conduct of valid test trials.

11.0 PRETEST AND FACILITY REQUIREMENTS

11.1 Detailed Test and Quality Control Procedures Required

Prior to conducting any test, Contractors are required to submit a detailed in-house test procedure to the COTR which includes:

1. A step-by-step description of the methodology to be used.

2. A written Quality Control (QC) Procedure which shall include calibrations, the data review process, report review, and the people assigned to perform QC on each task.

3. A complete listing of test equipment which shall include instrument accuracy and calibration dates.

4. Detailed check-off lists to be used during the test and during data review. These lists shall include all test procedure requirements. Each separate check off sheet shall identify the lab, test date, vehicle, and test technicians. These check sheets shall be used to document that all requirements and procedures have been complied for each test. The check sheets should be kept on file.

5. There shall be no contradiction between the laboratory test procedure and the

Contractor's in-house test procedure. The procedures shall cover all aspects of testing from vehicle receipt to submission of the final report. Written approval of the procedures must be obtained from the COTR before initiating the test program so that all parties are in agreement.

11.2 Road Test Surface

Unless specified otherwise, the road surface where the tests are performed shall be dry (without visible moisture on the surface). The roadway shall be straight and flat, with pavement in good condition. The roadway surface shall be constructed from asphalt or concrete, and free of potholes, bumps, and/or cracks that could cause the SV to pitch excessively.

Each trial shall be conducted with no other vehicles (except the POV and the POV tow vehicle, where applicable), obstructions, or stationary objects within one lane width of either side of the SV lane of travel.

The roadway used for the DBS tests may be delineated with up to two solid white lane lines. If a single lane line is used, the centerline of the SV and POV shall nominally be 6 ft from the inside edge of the line for the duration of the test. Additionally, the orientation of the SV, POV, and POV tow vehicle centerlines to the single lane line shall remain constant for the duration of the test. See S12.3.3.6 and S12.4.3.6 for lateral tolerances allowable during test conduct.

Example: If the single line is 6 ft (1.8 m) from left side of the SV centerline at the beginning of the test, the line shall also be 6 ft (1.8 m) from the left side of the POV centerline. If two lane lines are present, the distance between the inside edges shall be at least 12 ft (3.7 m), and the vehicles shall remain in the center of the lane for the duration of the trial.

11.3 Ambient Conditions

11.3.1 Ambient Temperature

The ambient temperature shall be between 32° F (0° C) and 100° F (38° C).

11.3.2 Wind Speed

The maximum wind speed shall be no greater than 22 mph (10 m/s).

11.3.3 Inclement Weather

Tests shall not be performed during periods of inclement weather. This includes, but is not limited to, rain, snow, hail, fog, smoke, and/or ash.

11.3.4 Visibility

The tests shall be conducted during daylight hours with good atmospheric visibility, defined as an absence of fog and the ability to see clearly for more than 3.1 mi (5000 m). The tests shall not be conducted with the vehicle oriented into the sun during very low sun angle conditions, where the sun is oriented 15 degrees or less from horizontal, and camera “washout” or system inoperability results.

All tests shall be conducted in an area void of overhead signs, bridges, or other significant structures over or near the testing site. Each trial shall be conducted with no vehicles (as indicted in S11.2), obstructions, or stationary objects within one lane width of either side the vehicle path.

11.4 Instrumentation Required

Each test vehicle shall be equipped with instrumentation and a data acquisition system.

Nominal equipment location and weight specifications are presented in Table 1.

Table 1 – Test Equipment Location and Weights

Equipment Description Typical Location Nominal Weight

Data Acquisition System Front passenger-side seat of SV 58 lbs (26 kg)

Integrated Inertial Measurement Unit and GPS (SV)

Antenna(s)1 mounted to the roof of the SV.

IMU/GPS near the center of the vehicle, just behind the front seats. GPS acquisition and ancillary equipment installed/secured on the rear passenger-side seat.

≈15 lbs (6.8 kg)

Programmable Brake Controller

Brake actuator is connected to the SV brake pedal, floor, and seat. The brake controller electronics box is typically secured in the footwell behind the front passenger seat.

Actuator ≈8 lbs (3.6 kg)

Electronics Box ≈15 lbs (6.8 kg)

Vehicle-to-vehicle range receiver (SV)

(wireless communication between the SV and POV tow vehicle)

Antenna mounted to the roof of the SV. Ancillary equipment secured on the rear passenger-side seat.

≈10 lbs (4.5 kg)

Integrated Inertial Measurement Unit and GPS POV tow vehicle)

Antenna(s)1 mounted to the roof of the POV tow vehicle. IMU/GPS near the center of the vehicle, just behind the front seats. GPS acquisition and ancillary equipment are installed and secured on the rear passenger-side seat.

≈15 lbs (6.8 kg)

Vehicle-to-vehicle range transmitter (POV tow vehicle)

(wireless communication between the SV and POV tow vehicle)

Antenna mounted to the roof of the POV tow vehicle. Ancillary equipment secured on the rear passenger-side seat.

≈8 lbs (3.6 kg)

1Two antennas are necessary if communication with a local base station is used (i.e., to provide real time kinematic correction of GPS position data).

11.4.1 Data Collection

All analog data shall be sampled at 100 Hz. Signal conditioning shall consist of amplification and digitizing. Amplifier gains are shall be selected to maximize the signal-to-noise ratio of the digitized data. Filtering of the data as it is collected is not necessary. However, if a filter is applied to incoming data, it shall be of a low-pass Butterworth specification with nominal cutoff frequencies selected to prevent aliasing. Data collection shall be initiated at least three seconds before the start of the test maneuver.

11.4.2 Sensors and Sensor Locations

An overview of the sensors used for the tests described in this document is provided in Table 2.

Table 2 – Recommended Sensor Specifications

Type Output Range Resolution Accuracy

Longitudinal Speed Sensor1 SV and POV longitudinal speed 0.1 – 62 mph

(0.1 -100 km/h)

0.1 mph

(0.2 km/h) +/- 0.25% of full scale

Rate Sensor1 SV Yaw Rate +/- 100 deg/s 0.01 deg/s +/- 0.25% of full scale

Accelerometer SV longitudinal deceleration +/- 2g +/- 0.001g +/- 0.01% of full scale

Load Cell Brake controller actuator force 0-300 lbf (0 – 1.3 kN)

0.25 lbf (1.1 N) +/- 0.08% of full scale

Rotary Encoder Brake controller actuator stroke 0 - 8 in (20.3 cm)

3200 pulses per inch

0.04 in (0.5 mm)

Load Cell Vehicle brake pedal force 0-300 lbf (0 – 1.3 kN)

0.25 lbf (1.1 N) +/- 0.08% of full scale

Position Sensor Vehicle brake pedal position 0 - 8 in (20.3 cm)

0.001 in (0.03 mm)

0.01 in (0.4 mm)

Position Sensor Vehicle throttle position 0 - 100 percent (normalized) 0.1 percent 0.1 percent

Various Longitudinal position of SV and POV 650 ft (200 m)

2 in (5 cm)

> 3.9 in (10 cm) absolute

Various Lateral position of SV and POV 650 ft (200 m)

2 in (5 cm)

> 3.9 in (10 cm) absolute

Vehicle Dimensional Measurements

Location of SV and POV tow vehicle GPS antennas; SV, POV, and POV tow vehicle centerlines; front-most SV bumper position; and rear-most POV bumper position

N/A 0.04 in (1 mm)

0.04 in (1 mm)

SV-to-POV static range

Distance between POV tow vehicle reference point (typically the longitudinal CG) and rear-most POV bumper position. Measurement taken with tow line tension determined in S12.1.1.

N/A 2 in (5 cm)

> 3.9 in (10 cm) absolute

POV Moving Platform Load

Tension in rope used to tow the POV and POV moving platform combination

0 – 500 lbf +/- 0.5 lbf (+/- 2.2 N)

+/- 2.5 lbf (+/- 11.1 N)

1Differentially corrected GPS may be used to provide data to calculate vehicle speed and yaw rate in lieu of direct measurement provided the resulting accuracy is comparable.

11.4.2.1 Vehicle Speed

SV and POV longitudinal vehicle speed shall be measured. Use of contact or non-contact based speed sensors is acceptable. Alternatively, GPS based sensors that have an update rate ≥ 100

Hz are acceptable. Sensor outputs are to be transmitted not only to the data acquisition system, but also to a dashboard display unit in the SV. This allows the driver to accurately monitor vehicle speed.

11.4.2.2 Yaw Rate

SV yaw rate shall be measured. Alternatively, differentially corrected GPS may be used to provide data to calculate yaw rate in lieu of direct measurement, provided the resulting accuracy is comparable.

11.4.2.3 Programmable Brake Controller Applications

To achieve accurate, repeatable, and reproducible brake applications, a programmable brake controller shall be used to apply all inputs described in this test procedure. The controller presently used by NHTSA consists of an electronically controlled linear actuator attached to the SV brake pedal with a hemispherical joint connected to a small bracket clamped to the pedal.

The opposing end of the actuator is attached to an inline load cell, which is then attached to a universal mounting fixture to provide reactionary support.

Note: Brake actuator stroke and application force, measured along a longitudinal axis of the actuator, are data channels typically provided by a programmable brake controller. These data shall be monitored and collected during test conduct to insure the brake controller is operating as commanded. However, due to the articulation of the SV brake pedal with respect to the actuator attachment point, the controller measurements may not be equivalent to the movement seen at the pedal itself.

To maximize consistency, the programmable brake controller shall have the capability to apply constant applications of brake pedal displacement (i.e., pedal travel) or application force. The mode of operation shall be user-selectable.

1. Constant actuator displacement. By maintaining constant actuator stroke, the position of the vehicle’s brake pedal remains fixed for the duration of the input. To achieve this, the brake controller modulates application force.

2. Constant actuator force. By maintaining constant actuator force, the force applied to the center of the vehicle’s brake pedal remains fixed for the duration of the input. To achieve this, the brake controller modulates actuator displacement.

11.4.2.4 Vehicle Brake Pedal

Vehicle brake pedal inputs shall be measured to facilitate correlation with those provided by the brake controller actuator. A single axis load cell shall be securely attached to vehicle brake pedal and positioned such that the normal force applied to the center of the brake pedal is measured. Use of a LASER-based linear position sensor shall be used to measure the position of the vehicle brake pedal horizontal centerline is recommended. This sensor shall be securely installed at a location unaffected by the brake controller hardware or operation.

11.4.2.5 Vehicle Throttle Pedal Position

Vehicle throttle pedal position measurements are required to verify the test input choreography has been correctly executed. Throttle pedal position shall be expressed as a percentage of the wide open throttle (WOT) pedal position.

11.4.2.6 Longitudinal and Lateral Position

Longitudinal and lateral position of the SV and POV can be measured by several different sensors and/or measurement techniques provided they meet the range, resolution, and accuracy specifications provided in Table 2. The longitudinal and lateral positions of the SV and POV shall be reported in the same coordinate system.

12.0 TEST EXECUTION AND TEST REQUIREMENTS

If the SV is equipped with an automatic transmission, all trials shall be performed in ‘‘Drive.’’ If equipped with a manual transmission, the highest gear capable of sustaining the desired test speed shall be used. Manual transmission clutches are to remain engaged during all test trials throughout the validity periods described in S12.3.7 and S12.4.7.

DBS system performance shall be evaluated in accordance with the following test procedures described in S12.3 and S12.4.

12.1 General Vehicle Prep and Pre-Test Conditioning

12.1.1 POV Moving Platform Tow Load Assessment

Since the instrumentation used to assess the POV speed and SV-to-POV headway originates at the POV tow vehicle, it is important that an accurate distance between the POV and POV tow vehicle during test conduct be known.

1. The POV shall be secured to the POV moving platform, and the platform attached to the POV tow vehicle in a manner described in S12.4.1.1 through S12.4.1.5.

2. The POV tow vehicle shall be driven at 20 mph (32.1 km/h), in a straight line, for approximately 350 ft (107 m) over the surface the DBS tests described in S12.4 will be performed. The POV tow vehicle driver shall use smooth throttle modulation to maintain speed with a tolerance of ±1.0 mph (±1.6 km/h).

3. While traveling at a steady 20 mph (32.1 km/h), the force required to pull the POV and POV moving platform combination shall be averaged over a 10 second sampling interval.

This value shall be used for the pre-test tow rope tensioning described in S12.4.1.6 and S12.4.2.3.

12.1.2 SV Brake Conditioning

To insure consistent performance, new brake components shall be conditioned once in the following manner:

1. From a speed of 35 mph (56.3 km/h), conduct ten (10) stops with an average deceleration of approximately 0.5 g per stop.

2. Immediately following the series of 35 mph (56.3 km/h) stops, conduct three additional stops from 45 mph (72.4 km/h) with ABS cycling for the majority of each braking event.

3. Following completion of the final stop, the SV shall be driven at a speed of 45 mph (72.4 km/h) for five minutes to allow brake temperature to stabilize.

12.1.3 Brake Warm-up and Temperature Maintenance

If the SV vehicle remains stationary for longer than 15 minutes any time prior to the conduct of the DBS tests described in S12.2 through S12.4, a series of three brake stops shall be performed with the SV from a speed of 45 mph (72.4 km/h) to warm the brakes. The longitudinal deceleration target of these stops shall be approximately 0.7 g.

A minimum of three (3) minutes must elapse between the completion of the last warm-up stop and the onset of a valid test trial, and between the completion of the individual test trials described in S12.3 and 12.4.

12.1.4 Instrumentation Initialization

All instrumentation shall be secure and properly configured. With all instrumentation off, the SV and POV tow vehicle shall be driven to an outdoor location unobstructed by buildings, overpasses, or other structures capable of interfering with the ability of the GPS equipment to acquire satellite-based position information, and real-time base station corrections (where applicable). At this location, the instrumentation shall be turned on, and static and dynamic GPS initializations be performed.

1. Static initialization

A. The transmissions of the SV and POV tow vehicle shall be placed in park (automatic transmission) or neutral with the emergency brake enabled (manual transmission).

B. The SV and POV tow vehicle shall remain at rest until transmissions from least six

(6) GPS satellites have been obtained and indicated by the vehicle’s respective instrumentation.

2. Dynamic initialization

A. The vehicles shall be driven in a straight line, at a speed of at least 35 mph (56.3 km/h) for at least 350 ft (107 m).

B. The vehicles shall be driven in three figure eight patterns. The radii of the turns shall be approximately 20 ft (6 m).

C. Repeat steps 12.1.4.2.A and 12.1.4.2.B until the vehicle’s respective instrumentation indicates that the required accuracies for position and heading have been achieved.

12.1.5 DBS System Initialization

Before DBS system performance can be properly assessed, some vehicles require a brief period of initialization. During this time, diagnostics to verify functionality and sensor calibrations are performed. If system initialization is required by a particular DBS system, the OVSC will obtain the appropriate procedure from the respective vehicle manufacturer, and provide it to the Contactor. The Contractor shall perform any OVSC-provided initialization schedule prior to performing the tests specified in S12.3 and S12.4.

12.2 Foundation Brake System Characterization

Foundation brake system characterization is used to objectively quantify the brake response of a vehicle without the contribution of advanced technologies such as DBS, brake assist, etc.

12.2.1 General Requirements

For an individual trial to be valid, the following must hold true throughout the test:

1. The SV driver seatbelt must be latched.

2. The front passenger seatbelt must be unlatched.

3. The SV shall be driven at the in the center of the travel lane.

4. The driver shall use the least amount of steering input necessary to maintain SV position in the center of the travel lane during the validity period specified in S12.2.5. Use of abrupt steering inputs or corrections shall be avoided.

5. The yaw rate of the SV must not exceed ±1.0 deg/s during the validity period specified in S12.2.5.

6. The lateral distance between the centerline of the SV, relative to the centerline of the roadway, in road coordinates, shall not exceed 1 ft (0.3 m) during the validity period specified in S12.2.5.

12.2.2 Nominal SV Speed

1. All foundation brake system characterization tests shall be initiated using a nominal SV speed of 45 mph (72.4 km/h).

2. The validity of the nominal SV speed shall be assessed at the instant the brake pedal application is initiated.

The SV speed shall not deviate more than ±1.0 mph (±1.6 km/h) during a time from two (2) seconds prior to the brake application, to the instant the brake application is initiated.

12.2.3 Throttle Pedal Inputs

1. For all tests the SV driver shall modulate the throttle, using smooth inputs, to maintain a constant SV speed for two (2) seconds prior to smoothly releasing the throttle. Abrupt throttle inputs shall be avoided.

2. The throttle pedal shall be fully released at least one (1) second before the brake pedal applications described in S12.2.4 are input. Throttle pedal release rate is unrestricted.

12.2.4 Brake Pedal Inputs

1. The SV brakes shall be brought up to operating temperature using the methods described in S12.1.3.

2. Choreography

A. Each test trial shall begin with the brake pedal in its natural resting position, with no preload or position offset.

B. For each test trial, the SV brakes are applied at least one (1) second after the throttle is released.

C. The onset of the brake application occurs when the brake actuator has applied

2.5 lbf (11 N) of force to the brake pedal.

D. The brake application force shall be measured by a load cell that measures the force applied by the brake controller actuator. Due to the articulation of the SV brake pedal with respect to the actuator attachment point, the force applied by the controller may not be equivalent to the force acting perpendicular to the pedal itself.

E. The validity of the throttle release-to-brake application choreography shall be assessed from the instant the brake pedal application is initiated.

3. Application Magnitude

A. For each test trial, the brake pedal displacement necessary to realize a deceleration of at least 0.7g shall be applied in conjunction with the application rate specified in S12.2.4.4.

B. If the SV cannot achieve a deceleration of 0.7g, the brake pedal displacement need to realize maximum deceleration shall be applied during each test trial.

4. Application Rate

A. The SV brake pedal application rate shall be 1 to 2 in/s (25 to 51 mm/s).

B. Application rate is defined as the slope of a first order linear regression line applied to brake pedal position data over a range from 25 to 75% of the commanded input magnitude.

12.2.5 Validity Period

1. The valid test interval begins two (2) seconds prior to the SV throttle release.

2. The valid test interval ends when either the SV comes to a stop.

12.2.6 End of Test Instructions

1. For each test trial, after the validity period specified in S12.2.5 is complete, the SV driver shall manually apply force to the brake pedal, disengage the programmable brake controller, and place the transmission in park (automatic transmission) or neutral (manual transmission).

2. The brake system characterization test trial is complete.

12.2.7 Number of Test Trials

A total of eight (8) valid trials shall be performed for brake system characterization.

12.2.8 Brake System Characterization Output

Brake system characterization data shall be used to calculate the brake pedal input magnitudes needed for the tests described in S12.3 and S12.4.