J.4 Dynamic Brake Support Performance Evaluation Confirmation Test, October, 2015.pdf

DYNAMIC BRAKE SUPPORT

PERFORMANCE EVALUTION CONFIRMATION

TEST

FOR THE

NEW CAR ASSESSMENT PROGRAM

October 2015

U. S. Department of Transportation National Highway Traffic Safety Administration

1200 New Jersey Avenue SE Washington, DC 20590

J.4

DYNAMIC BRAKE SUPPORT PERFORMANCE EVALUTION

TABLE OF CONTENTS

LIST OF ACRONYMS

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

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

16.0 TIME-TO-COLLISION CALCULATIONS

LIST OF ACRONYMS

ACC Adaptive Cruise Control

AEB Automatic Emergency Brake

ASTM American Society of Testing and Materials

CG Center of Gravity

CO Contracting Officer (NHTSA)

COR Contracting Officer’s Technical Representative

DAS Data Acquisition System

DBS Dynamic Brake Support

DTC Diagnostic Trouble Code

FCW Forward Coll ision Warning

GAWR Gross Axle Weight Rating

GFE Government Furnished Equipment

GPS Global Positioning System

GVWR Gross Vehicle Weight Rating

IBT Initial Brake Temperature

IMU Inertial Measurement Unit

LIDAR Light Detection and Ranging

LRT Lateral Restraint Track

NHTSA National Highway Traffic Safety Administration

NIST National Institute of Standards and Technology

PFC Peak Friction Coefficient

POV Principal Other Vehicle

RADAR Radio Detection and Ranging

RCS Radar Cross Section

SSV Strikeable Surrogate Vehicle

SV Subject Vehicle

STP Steel Trench Plate

TTC Time to Coll ision

UHMW Ultra-high Molecular Weight Polyethylene

UVW Unloaded Vehicle Weight

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 10,000 pounds (4,536 kilograms) or less. 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 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 Contracting Officer Technical Representative (COR).

2.0 GENERAL REQUIREMENTS

This document describes the methods used by NHTSA to evaluate DBS performance on the test track. In the first three scenarios, a subject vehicle (SV) approaches a stopped, slower-moving, or decelerating principal other vehicle (POV) in the same lane of travel. For these tests, the POV is a strikeable object with the characteristics of a compact passenger car1. The fourth scenario is used to evaluate the propensity of a DBS system to inappropriately activate in a non-critical driving scenario that does not present a safety risk to the SV occupant(s).

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 a NHTSA representative. All data collected during 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 NHTSA. Such permission can never be assumed.

1 The specific attributes of the POV are described in S7.4.

2. All communications with vehicle manufacturers shall be referred to NHTSA, and at no time shall the Contractor release test data without permission from NHTSA.

3. 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 at all times.

4. 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.

5. 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 NHTSA.

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 COR, a NHTSA representative present at the test site, or to NHTSA.

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

This service shall be included as an incidental part of the test program and will not result in any additional cost to 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 a NHTSA representative.

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 COR 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

COR.

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 COR.

6.1 Test Data

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

6.2 Test Report

6.2.1 Report Content

The test report shall include all of the items shown in the Sample Test Report (see Section 14.3.4). The text and data sheet portion of the test report shall be in Microsoft Word format.

Digital photographs shall be in JPEG format. The Contractor shall submit two (2) CDs or DVDs, or one (1) USB drive, and one (1) paper copy of the test report to the following address:

U. S. Department of Transportation National Highway Traffic Safety Administration 1200 New Jersey Avenue SE Washington, DC 20590

6.2.2 Report Submission

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

6.3 Test Video

NHTSA shall receive one (1) copy of the color video for each test, and the copies shall be mailed directly to NHTSA within four (4) weeks of the vehicle test. The master recording for each of the test videos shall be retained by the Contractor, but will be made available to NHTSA upon request. See S9.1 for a description of the video to be taken during DBS 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 a report. Invalidated test reports will not be publicly released.

RETEST CONDITIONS

Failure of the Contractor to obtain the specified data and to maintain acceptable test parameter tolerances 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 NHTSA 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 COR.

6.4.2 Conditions for Partial Payment

The Contractor shall exercise reasonable and foreseeable control to ensure that no data is lost or rendered useless. If non-critical data (such as camera failure) and/or 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 NHTSA, reproducible copies of all test data, pictures, videos, and applicable 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 reports, test data on a CD or DVD, test videos, and/or test still photographs, at a reasonable cost to the purchaser, but only after NHTSA representative has advised the Contractor that the results of that particular test have been released to the public by NHTSA.

6.7 Indicant Failure Notification

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

Note: In the event of a failure, a post-test calibration check of critically sensitive test equipment and instrumentation may be required for verification of accuracy. The necessity for the calibration shall be at the COR'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 on 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. The spare tire, jack, lug wrench, and tool kit are located in the vehicle cargo area (if applicable).

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

7.2 Notification of COR

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

7.3 Government Furnished Equipment (GFE)

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

7.4 POV Characteristics

The Contractor shall use a strikeable object with the characteristics of a compact passenger car 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 the SV is traveling directly behind the POV and heading in the same direction within ±5 degrees.

A. Body panels and rear bumper shall be white in color.

B. Simulated body panel gaps shall be present.

C. The simulated rear glass and tires shall be black.

D. A rear-mounted United States-specification license plate, or reflective simulation thereof, shall be installed.

2. RADAR return characteristics, classified using the 24 GHz and 77 GHz bands, representative of a high-volume passenger car when approached from behind with a SV heading angle of ±5 degrees.

3. Remains consistently shaped (e.g., visually, dimensionally, internally, and from a RADAR sensing perspective) within each test series.

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

5. Inflicts 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, S12.4, and S12.5 satisfies the requirements of S7.4.1 through S7.4.5.

Note: From the face of the rear bumper to a plane defined by the center of the rear wheels, the POV used by NHTSA, the Strikeable Surrogate Vehicle (SSV), is dimensionally similar to a small high-volume hatchback. To reduce the potential of damage to the SV during an impact, the SSV is constructed from lightweight composite materials with favorable strength-to-weight characteristics, including carbon fiber, Kevlar, phenolic, and Nomex honeycomb. The SSV is wrapped with a commercially-available vinyl material to simulate paint on the body panels and rear bumper, and a tinted glass rear window. The taillights, rear bumper reflectors, and third brake light from a 2011 Ford Fiesta hatchback are installed. The contour of the SSV rear bumper has been designed to accommodate impacts from wide range of SVs (i.e., vehicles possessing a variety of front bumper heights), and features a RADAR cross section (RCS) representative of a real-world light vehicle. A 34 x 14 x 8 in (864 x 356 x 203 mm) foam bumper is attached to the rear of SSV to reduce the peak forces realized shortly after an SV impact occurs. This bumper features a 60-in convex radius and is made from lightweight foam with a neoprene cover.

7.5 Moving the POV

To perform the Slower-Moving and Decelerating POV tests described in S12.4 and S12.5, respectively, the Contractor’s test equipment must:

1. Accurately control the nominal POV speed up to 35 mph (15.6 km/h).

2. Accurately control the lateral position of the POV within the travel lane.

3. Allow the POV to move away from the SV after an impact occurs.

One way to satisfy these requirements is by using a moving platform. Here, all POV movement is controlled by the platform; the POV is simply secured to it. However, if a moving platform is used, steps to avoid confounding test outcome and/or DBS system misclassification shall be made:

1. To reduce the potential of the POV moving platform confounding RADAR-based system operation, neither the platform nor its frame (if applicable) shall be fabricated from electrically conductive materials, unless the Contractor can demonstrate the equipment does not adversely affect the RCS realism of the surrogate vehicle secured to it.

2. To reduce the potential of the moving platform to confound LIDAR sensor or camera-based system operation, its surfaces shall be low-gloss or oriented in a position that eliminates glare when performing tests in direct sunlight. If applicable, the Contractor shall demonstrate provisions to reduce glare from the moving platform do not affect the RCS realism of the surrogate vehicle secured to it.

Note: To facilitate POV movement, NHTSA secures its SSV to a two-piece energy-dissipating carbon fiber frame that moves longitudinally along two-rail metal track. Shortly after the SV impacts the rear bumper of the SSV, a sliding section of the frame (subsequently referred to as the “slider”) collapses within a second structure (subsequently referred to as the “load frame”).

As the slider moves, it engages with the load frame via four energy-absorbing nylon straps.

NHTSA’s two-rail track features nine modular sections designed to be quickly assembled in the field. Some basic specifications include:

1. The total assembled length of the track is 72 ft (22 m).

2. The first section is 8 ft (2.4 m) long, fabricated from 2 x 2 x 0.25 in (51 x 51 x 6 mm) steel L-channels spaced 2 ft (0.6 m) apart using 1.5 x 1.5 x 0.19 in (38 x 38 x 5 mm) square steel tubing.

A. The SSV is secured at the end of this track nearest to the SV before each test

B. The front-most horizontal edges of the L-channels (i.e., those facing the SV as it approaches the SSV) feature 45-degree tapers to attenuate their RCS.

C. The RCS of the first two 1.5 x 1.5 x 0.19 in (38 x 38 x 5 mm) square tubes is attenuated by securing two shallow aluminum ramps covered with RADAR-absorbing material to the front vertical face of each tube.

3. Eight sections are 8 ft (2.4 m) long, fabricated from 2 x 2 x 0.25 in (51 x 51 x 6 mm) 6061-

T6 aluminum L-channels spaced 2 ft (0.6 m) apart using 1.5 x 1.5 x 0.19 in (38 x 38 x 5

mm) square 6061-T6 aluminum tubing.

A. A trailer hitch and steel support frame is attached to the end of the last section to allow the entire track to be towed.

B. A 43 x 20 x 27 in (1092 x 508 x 686 mm) foam cushion attached to the front face of the trailer hitch support frame (i.e., the end opposite the impact point) dampens the impact of the SSV reaching the end of the track after an SV impact, and prevents the SSV from making direct contact with the frame.

4. The track is supported by a series of 19 ultra-high molecular weight (UHMW) polyethylene skids designed to position the top face of the track 2.5 in (64 mm) from the ground. It is anticipated the track height will be low enough to evaluate any light vehicle without the track contacting underside components of the SV.

5. The bottom of each track section incorporates a “notch” to interface with the lateral restraint track (LRT) described in S7.6.

The combination of the two-rail track and LRT allow the SSV to be accurately and repeatably positioned in the center of the travel lane during Stopped, Slower-Moving and Decelerating POV tests. The interaction of the bumper cushion, slider, load frame, and two-rail track allow the forces acting on the SSV to be incrementally realized, letting the SSV move longitudinally away from the SV after an impact occurs. After impacting the SSV, the SV driver uses the steering wheel to maintain SV position in the center of the travel lane, thereby straddling the two-rail track. As described in S12.3.8, S12.4.8, and 12.5.6, the SV driver must manually apply the SV brakes after a POV (i.e., SSV) impact. This avoids a situation where the SV is still applying force to the rear of the SSV when it stops at the end of the two-rail track.

7.6 POV Lateral Restraint Track (LRT) (Optional Equipment)

An LRT may be used to help the POV, and the apparatus the POV is attached to, maintain a straight path during conduct of the Slower-Moving and Decelerating POV tests described in S12.4 and S12.5. The LRT must be made from a low-gloss, non-conductive material such as UHMW polyethylene, and be black or dark grey in color.

Note: The LRT used by NHTSA consists of 24.5-ft (7.5 m) long UHMW polyethylene strips, assembled in series, to produce a single 1000-ft (305 m) ”monorail” in the center of the travel lane. Each LRT strip has a nominal rectangular cross section of 0.5 x 4 in (13 x 102 mm). To allow for thermal expansion and contraction, the fasteners used to secure the strips to the test surface reside in slotted grooves with a gap of 3 to 6 in (76 to 152 mm) between each strip.

7.7 POV Tow Vehicle (Optional Equipment)

During conduct of the Slower-Moving and Decelerating POV tests described in S12.4 and S12.5, a tow vehicle may be used to bring the POV and POV Moving Platform assembly to the desired test speed. However, since a towed POV is not expected to contain any instrumentation itself, its kinematic data must be derived by translating known parameters of the POV tow vehicle back to the POV. The accuracy of this translation strongly depends on maintaining a known longitudinal and lateral distance between the POV and POV tow vehicle. To promote safe test conduct, the distance between the POV and POV tow vehicle shall be at least 74 ft (22.6 m); the actual distance shall be measured and recorded in S8.3.10.

7.8 Steel Trench Plate (STP)

Steel trench plates (STPs) are often used in road construction to temporarily cover sections of pavement unsafe to drive over directly (typically during repair). The STP used in this test shall be made from ASTM A36 steel, and measure 8 ft x 12 ft x 1 in (2.4 m x 3.7 m x 25 mm).

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 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 and Decelerating POV tests described in S12.4 and S12.5, one GPS receiver shall be installed in the SV and one in the POV, POV moving platform, or POV tow vehicle. For these tests, 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), installed in the SV to record data from the sensors described in S11.4.2.

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 “International Organization for Standards (ISO) 100 12- 1, "Quality Assurance Requirements for Measuring Equipment," Part 1 : "Meteorological Confirmation System for Measuring Equipment;" American National Standards Institute (ANSI)/National Conference of Standards Laboratories (NCSL) 2540-1, "General Requirements for Calibration Laboratories and Measuring and Test Equipment;" or comparable alternative standards to MIL-C-45662A approved by the

NHTSA COR.

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) standards, shall be maintained for all measuring and test equipment. The calibration frequency may be increased if deemed necessary by NHTSA.

3. All measuring instruments, test equipment, and test standards shall 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

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

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

B. Measurement range

C. Accuracy

D. Calibration interval

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

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

5. 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 COR and shall be included in the final test report. The calibration system will need the acceptance of the COR before testing commences.

6. Test equipment shall receive 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 the 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 COR's discretion and will be performed without additional cost to NHTSA.

8.3 SV Measurement and Preparation

1. All sensors used by the SV DBS 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, if needed to perform the test, using instructions provided by NHTSA. If this requires the airbag connector(s) be physically separated, installation of resistors at the affected connector(s) may be necessary to ensure proper DBS functionality during test conduct. If the use of resistors is required, NHTSA shall provide the appropriate resistance values and installation instructions to the Contractor.

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 level must not fall below 75 percent capacity during the testing.

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

7. Vehicle load shall include the unloaded vehicle weight (UVW) plus a driver, experimenter (if required), and instrumentation without exceeding the lesser of either

(1) a maximum of 610 lb (277 kg) or (2) vehicle Gross Vehicle Weight Rating (GVWR) and all Gross Axle Weight Ratings (GAWR).

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

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

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

11. If a POV tow vehicle is used, A. The POV shall first be set to the furthest distance from the rear POV tow vehicle as permitted by the test apparatus (i.e., the orientation used at the onset of the tests performed in S12.3, S12.4, and S12.5).

B. The longitudinal distance from the GPS antenna of the POV tow vehicle to the rear-most position of the POV rear bumper shall then 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 event 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 “NHTSA 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. NHTSA 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 Test Video Editing

The test video 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 or 8.5 x 11 inch color prints, or 2048 x 1080 pixel digital pictures), properly focused for clear images are required for the test:

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

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

3. SV tire placard

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 by the driver during a rear-end crash avoidance maneuver. 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 intervention is largely the same: to supplement the driver’s commanded brake input by increasing the output of the foundation brake system. In some situations, the increased braking 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 DBS interventions are designed to occur late in the pre-crash timeline, and the driver has already initiated braking, DBS systems are not required to alert the driver that a DBS intervention has occurred.

10.2 System Attributes

The DBS system shall provide for continuous monitoring of vehicles in the forward pathway of the SV vehicle. 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.

10.3 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 in 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.

With the exception of those used to directly evaluate false positive propensity (described in S12.6), the tests described in this document are performed using clear roadway lanes within the idealized confines of a test track. Careful and deliberate throttle and steering inputs are required from the SV driver during all tests. As such, DBS system suppression is not expected to occur during the conduct of valid test trials described in S12.3, S12.4, and S12.5 of this document.

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 COR 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 Contractor-assigned staff 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 sheets used during the test and during data review. These sheets shall include lists of all test procedure requirements. Each separate check-off sheet shall identify the lab, test date, vehicle, and test technician(s), and shall be used to document that all requirements and procedures have been completed 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 COR before initiating the test program so that all parties are in agreement.

11.2 Road Test Surface

Unless specified otherwise, the road test surface shall be dry (without visible moisture on the surface), straight, and flat, with a consistent slope between level and 1 percent. The road surface shall be constructed from asphalt or concrete and shall be free of irregularities, undulations, and/or cracks that could cause the SV to pitch excessively.

The road test surface must produce a peak friction coefficient (PFC) of at least 0.9 when measured using an American Society for Testing and Materials (ASTM) E1136 standard reference test tire, in accordance with ASTM Method E 1337-90, at a speed of 40 mph (64.4 km/h), without water delivery. The test track PFC shall be documented.

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 (1.8 m) 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, S12.4.3, S12.5.3, and S12.6.2.3 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 45°F (7°C) and 104°F (40°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 at least 3.1 mi (5.0 km). The tests shall not be conducted with the SV and POV oriented into the sun during very low sun angle conditions (where the sun is oriented 15 degrees or less from horizontal) as camera “washout” or system inoperability may result.

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 SV path. Shadows cast by objects other than the SV, POV, POV test apparatus, POV tow vehicle (where applicable), or steel trench plate (described in S12.6) shall not be present in the SV lane of travel, or within one lane width of either side of the SV 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 SV rear cargo area (e.g., trunk) ≈58 lb (26 kg)

Integrated Inertial Measurement Unit (IMU) and GPS (SV)

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

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

≈15 lb (7 kg)

Programmable Brake Controller (SV)

Brake actuator is connected to the SV brake pedal, floor, and seat. The brake controller electronics box and batteries are typically secured on the passenger seat behind the driver seat.

Actuator, Electronics Box, Batteries, Cables, Hardware, etc.

≈138 lb (63 kg)

Vehicle-to-vehicle range receiver (SV)

(wireless communication between the SV and POV or POV tow vehicle)

Antenna mounted to the roof of the SV. Ancil lary equipment secured in the SV rear cargo area. ≈10 lb (5 kg)

Integrated Inertial Measurement Unit and GPS (POV or POV tow vehicle)

Antenna(s)1 mounted to the POV or to the roof of the POV tow vehicle. IMU/GPS securely positioned within the POV, or just behind the front seats of the POV tow vehicle, near the center of either unit. GPS acquisition and ancil lary equipment securely positioned within the POV or on the rear driver-side seat of the POV tow vehicle.

≈15 lb (7 kg)

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

(wireless communication between the SV and POV or POV tow vehicle)

Antenna mounted to the POV or to the roof of the POV tow vehicle. Ancil lary equipment secured within the POV or on the rear passenger-side seat of the POV tow vehicle.

≈8 lb (4 kg)

Programmable Brake Controller (POV)

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

Actuator ≈8 lb (4 kg)

Electronics Box ≈15 lb (7 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 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 (during the trial or immediately following), it shall be of a low-pass, 6th order Butterworth with a corner frequency of 3 Hz to prevent aliasing. Data collection shall be initiated at least one second before the onset of the validity periods defined in S12.3.7, S12.4.7, S12.5.8, S12.6.1.4, and S12.6.2.7.

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.

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 of at least 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 data may be used 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 SV brake pedal inputs, a programmable brake controller shall be used for all brake applications described in this test procedure. The controller shall have the capability to operate in one of two user-selectable closed-loop control modes: (1) brake pedal displacement feedback (i.e., pedal travel), and (2) combined brake pedal displacement and application force feedback (subsequently referred to as a “hybrid” application).

1. Constant pedal 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. Hybrid control. Hybrid control uses position-based control to command the initial brake application rate and actuator position, then changes to force-based control to command a reduction of applied force to a predetermined floor. This force is maintained until the end of the braking maneuver by allowing the brake controller to modulate actuator displacement.

Table 2 – Recommended Sensor Specifications

Type Output Range Resolution Accuracy

Longi tudinal 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 ful l sca le range

Rate Sensor1 SV yaw rate +/- 100 deg/s 0.01 deg/s +/- 0.25% of ful l sca le range

Accelerometer SV and POV longitudinal deceleration +/- 2g 0.001g +/- 0.01% of ful l sca le range

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

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

Rotary Encoder SV brake controller actuator position 0 - 8 in (0 – 20.3 cm)

3200 pulses per inch

0.04 in (0.5 mm)

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

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

Pos i tion Sensor SV brake pedal position 0 - 8 in (0 – 20.3 cm)

0.001 in (0.03 mm)

0.01 in (0.4 mm)

Pos i tion Sensor SV throttle position 0 - 100 percent (normal ized) 0.1 percent 0.1 percent

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

2 in (5 cm)

At least 3.9 in (10 cm) absolute

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

2 in (5 cm)

At least 3.9 in (10 cm) absolute

Data Flag (FCW Alert)

Signal from SV forward coll ision warning (FCW) system indicating whether the alert is in operation.

0 – 10V N/A Output response better than 10 ms

Vehicle Dimensional Measurements

Location of SV and POV or POV tow vehicle GPS antennas; SV, POV, and POV tow vehicle centerlines (where applicable); front-most SV bumper pos ition; and rear-most POV bumper pos ition.

N/A 0.04 in (1 mm)

0.04 in (1 mm)

SV-to-POV Static Range

Dis tance between POV or POV tow vehicle reference point (typically the longitudinal center of gravity (CG)) and rear-most POV bumper position.

N/A 2 in (5 cm)

At least 3.9 in (10 cm) absolute

1Di fferentially corrected GPS may be used to provide data to calculate vehicle speed and yaw rate in l ieu of di rect measurement provided the resul ting accuracy i s comparable.

Note: The stringency of the test procedures described in S12.3 through S12.6 is intended to be independent of how the SV brakes are applied. However for some vehicles, the interaction of a particular application mode and specific DBS operational characteristics can adversely affect system performance. For this reason, a NHTSA representative may specify to the Contractor which programmable brake controller mode shall be used for a vehicle’s respective evaluation.

11.4.2.4 SV Brake Pedal Force and Position

SV 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 the SV brake pedal and positioned such that the normal force applied to the center of the brake pedal is measured. The sensor used to measure brake pedal position shall be securely installed at a location unaffected by the brake controller hardware or operation.

Note: Brake actuator stroke and application force are measured along a longitudinal axis of the actuator. These data channels shall be monitored and collected during test conduct to ensure 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.

11.4.2.5 SV Throttle Pedal Position

SV 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. The longitudinal distance between the front of the SV and the rearmost location of the POV shall be transmitted to a dashboard display unit in the SV. This allows the driver to accurately monitor SV-to-POV headway (which is particularly important for the Decelerating POV tests described in S12.5).

11.4.2.7 Forward Collision Warning (FCW) Activation Flag

The Forward Collision Warning (FCW) activation flag shall indicate when the system has issued an alert to the SV driver. The FCW modality shall be either the auditory alert, or the alert indicated to the test conductor by a NHTSA representative. The FCW activation flag shall be recorded from a discrete signal and/or other methods that clearly indicate when the alert has been issued provided there is no damage to the SV.

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, S12.4.7, S12.5.8, S12.6.1.4, and S12.6.2.7.

DBS system performance shall be evaluated in accordance with the following test procedures described in S12.3 through S12.6.

12.1 General Vehicle Preparation and Pre-Test Conditioning

12.1.1 SV Brake Burnish

To achieve full brake system capability, and to ensure consistent performance, the procedure defined in S14.1.2 and S14.1.3 of FMVSS No. 135 TP-135-01 shall be used to burnish new SV brake components:

1. Load the SV to its Gross Vehicle Weight Rating (GVWR).

2. From a speed of 49.7 mph (80 km/h), perform 200 stops with an average deceleration of

0.31g (3.0 m/s²) during each stop.

A. Each stop shall be performed with the transmission in gear.

B. The Initial Brake Temperature (IBT), defined as the average brake pad or lining friction material temperature on the highest-temperature axle of the SV at the onset of a test trial, shall be ≤ 100°C (212°F) at the onset of each stop.

C. The interval from the onset of one stop to the onset of the next is either the time necessary to reduce the IBT to ≤ 212°F (100°C), or the distance of 1.24 miles (2 km), whichever occurs first.

D. Accelerate to 49.7 mph (80 km/h) after each stop and maintain that speed until initiating the next.

12.1.2 SV Brake Warm-up and Temperature Maintenance

The IBT shall be between 149°F (65°C) and 212°F (100°C) at the onset of each test described in S12.2 through S12.6.

1. If the IBT is <149°F (65°C), the brakes are heated to the IBT by making one or more brake applications from a speed of 31.1 mph (50 km/h), at a deceleration rate not greater than 0.31g (3.0 m/s²).

2. If the IBT is > 212°F (100°C), the SV shall be driven at speeds up to 62.1 mph (100 km/h) until the IBT specified in S12.1.2 is reached.

12.1.3 Instrumentation Initialization

All instrumentation shall be secure and properly configured. With all instrumentation off, the SV and POV, POV moving platform, or POV tow vehicle shall be driven to an outdoor location unobstructed by buildings,…