`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Laboratory Test Procedure for Dynamic
`Rollover
`The Fishhook Maneuver Test Procedure
`
`New Car Assessment Program (NCAP)
`
`
`
`MARCH 2013
`
`
`U.S. Department of Transportation
`National Highway Traffic Safety Administration
`1200 New Jersey Avenue SE
`Washington, DC 20590
`
`-1
`
`Magna - IPR2020-00777 - Ex. 2008 - 001
`
`

`

`LABORATORY TEST PROCEDURE
`TABLE OF CONTENTS
`
`
`
`INTRODUCTION ................................................................................................... 4
`
`1.0
`
`1.1 General ................................................................................................................ 4
`
`1.2 Rollover Resistance Requirements of the TREAD Act ................................ 4
`
`1.3 Recent NHTSA Light Vehicle Dynamic Rollover Propensity Research .... 4
`
`2.0 TEST EQUIPMENT .............................................................................................. 5
`
`2.1 Vehicle Load Configurations ............................................................................ 5
`
`2.2 Safety Outriggers ............................................................................................... 7
`
`2.3 Tires ..................................................................................................................... 8
`
`2.4 Data Collection ................................................................................................... 9
`
`2.5
`
`Instrumentation ................................................................................................ 10
`
`2.6 Steering Machine ............................................................................................. 14
`
`3.0 TEST MANEUVERS ........................................................................................... 14
`
`3.1 Slowly Increasing Steer .................................................................................. 14
`
`3.2 NHTSA Fishhook Maneuver .......................................................................... 17
`
`4.0
`
`ITEMS PERTAINING TO TEST CONDUCT ................................................... 26
`
`4.1 Definition of Two-Wheel Lift ........................................................................... 26
`
`4.2 Vehicle Test Configurations ........................................................................... 26
`
`4.3 Road Test Surface .......................................................................................... 27
`
`4.4 Ambient Conditions ......................................................................................... 28
`
`4.5 Calibration Data ............................................................................................... 28
`
`-2
`
`Magna - IPR2020-00777 - Ex. 2008 - 002
`
`

`

`4.6 Tire Break-In Procedure ................................................................................. 29
`
`4.7 Static Datums ................................................................................................... 29
`
`4.8 Vehicle Gear Selection ................................................................................... 30
`
`4.9 Outrigger Adjustment ...................................................................................... 30
`
`4.10
`
` Videotape Documentation ......................................................................... 31
`
`4.11
`
` Summary of Tests To Be Performed For Each Vehicle........................ 31
`
`4.12
`
` Summary of Metrics Measured For Each Vehicle ................................. 32
`
`4.13
`
` Post Processing .......................................................................................... 32
`
`5.0 REFERENCES .................................................................................................... 33
`
`
`-3
`
`Magna - IPR2020-00777 - Ex. 2008 - 003
`
`

`

`FISHHOOK MANEUVER TEST PROCEDURE
`
`
`
`1.0
`
`INTRODUCTION
`
`1.1 General
`
`This document describes the test procedure used by the National Highway
`
`Traffic Safety Administration's (NHTSA) New Car Assessment Program (NCAP)
`to evaluate light vehicle dynamic rollover propensity. The procedure is
`comprised of one characterization maneuver and one rollover resistance
`maneuver.
`
`1.2 Rollover Resistance Requirements of the TREAD Act
`
`Section 12 of the "Transportation Recall, Enhancement, Accountability and
`
`Documentation (TREAD) Act of November 2000" reflects the desire of Congress
`to supplement SSF [Static Stability Factor] with a dynamic stability test using
`vehicle maneuvers. Congress directed NHTSA to "develop a dynamic test on
`rollovers by motor vehicles for a consumer information program; and carry out a
`program conducting such tests." NHTSA's NCAP Light Vehicle Dynamic
`Rollover Propensity Test Procedure described in this document was developed
`as part of NHTSA's effort to fulfill the requirements of the TREAD Act.
`
`1.3 Recent NHTSA Light Vehicle Dynamic Rollover Propensity Research
`
`During the spring through fall of 2001 NHTSA performed an extensive
`
`assessment of many test track maneuvers potentially capable of quantifying on-
`road, non-tripped vehicle rollover propensity. In brief, five vehicle
`characterization and nine dynamic rollover propensity maneuvers were studied.
`Each maneuver was either discarded or retained for subsequent program
`phases. The 2001 research project is documented in [1].
`
`-4
`
`Magna - IPR2020-00777 - Ex. 2008 - 004
`
`

`

`During the spring through fall of 2002 NHTSA performed a comprehensive
`
`evaluation of rollover resistance for a broad spectrum of twenty-six light vehicles.
`The test vehicles were evaluated with one Characterization maneuver and two
`Rollover Resistance maneuvers. Up to two load configurations per vehicle were
`used. The 2002 research project is documented in [2].
`
`2.0 TEST EQUIPMENT
`
`2.1 Vehicle Load Configurations
`
`NHTSA's dynamic rollover propensity test procedure uses one of two
`
`loading configurations: Nominal or Multi-Passenger. A description of each
`configuration is provided below.
`
`Both vehicle load configurations include instrumentation, a steering
`
`machine, and outriggers. Test vehicle bumper assemblies are removed for
`outrigger installation. The reduction in vehicle weight due to the removal of the
`bumpers is offset by the additional weight of the outriggers and their mounting
`system. The outrigger system typically outweighs the bumper assemblies.
`
`2.1.1 Nominal Load Configuration
`
`The Nominal Load Configuration consists of the driver, instrumentation,
`
`steering machine, outriggers, and full tank of fuel. Weight and location
`specifications for the data acquisition system and steering machine are
`presented in Table A.1 and Fig A.1.
`
`Non-pickup truck vehicles with only front designated seating positions use
`
`the Nominal Load Configuration.
`
`
`
`-5
`
`Magna - IPR2020-00777 - Ex. 2008 - 005
`
`

`

`Table A.1. Equipment Location and Weight
`
`Equipment
`
`Location
`
`Data Acquisition
`System
`
`Front passenger seat
`
`Steering Machine Handwheel
`
`Steering Machine
`Electronics Box
`
`Passenger row foot well behind the front
`passenger seat. If vehicle does not have a
`rear passenger row foot well, the
`Electronics Box should be placed in the
`front passenger seat foot well.
`
`
`
`2.1.2 Multi-Passenger Configuration
`
`Weight,
`typical (lbs)
`
`58
`
`31
`
`39
`
`The Multi-Passenger Configuration includes all elements of the Nominal
`
`Load Configuration plus ballast in the form of water dummies. Water dummies
`are installed as follows:
`
`For vehicles with three or more designated rear seating positions, three 175
`
`lb. water dummies are used. The water dummies shall be positioned on the rear
`seats (second seating row) closest to driver and front passenger seats (first
`seating row). If there are only two seating positions in the second seating row,
`the third water dummy shall be placed in the center of the third seating row,
`provided it is a designated seating position. Refer to Fig A.2.
`
`For vehicles with two designated rear seating positions, two 175 lb. water
`
`dummies shall be positioned in the rear seats. Refer to Fig A.3.
`
`-6
`
`Magna - IPR2020-00777 - Ex. 2008 - 006
`
`

`

`For pickups with only front designated seating positions, three 175 lb. water
`
`dummies will be used. The water dummies shall be positioned behind the cab in
`a manner that emulates a second seating row. If it is not possible to fit three
`water dummies directly behind the cab, the third water dummy shall be placed in
`the center of a simulated third seating row. Refer to Fig A.4.
`
`For pickups with two seating rows, three 175 lb. water dummies will be
`
`used. If the second seating row includes three designated seating positions,
`each water dummy shall be placed in these positions. If the second seating row
`includes two designated seating positions, two 175 lb. water dummies shall be
`positioned in the second seating row of the cab, and the third water dummy shall
`be positioned behind the cab in a manner that emulates the center seating
`position of a third seating row. Refer to Fig A.5.
`
`For all vehicles, if the Multi-Passenger Configuration results in the vehicle
`
`exceeding its Gross Vehicle Weight Rating (GVWR) and/or rear Gross Axle
`Weight Rating (GAWR), the weight of each dummy will be equally reduced until
`the GVWR and/or rear GAWR are no longer exceeded. The weight of the water
`dummies shall not be reduced if only the front GAWR is exceeded and the front
`axle weight does not exceed the front GAWR by more than 50 pounds, i.e., if the
`Multi-Passenger Configuration results in the vehicle exceeding its front GAWR,
`and its GVWR and/or rear GAWR, the weight of each dummy will be equally
`reduced until the GVWR and rear GAWR are no longer exceeded and the front
`GAWR is not exceeded by more than 50 pounds.
`
`For non-pickup truck vehicles with only front designated seating positions,
`
`the Multi-Passenger Configuration is omitted from the test matrix.
`
`2.2 Safety Outriggers
`
`Safety outriggers are installed on all test vehicles during all test maneuvers.
`
`NHTSA uses outriggers machined from 6Al-4V titanium. NHTSA's "short"
`outriggers are used for vehicles with baseline weights under 3,500 pounds in a
`baseline condition (as delivered); "standard" outriggers are used for vehicles with
`
`-7
`
`Magna - IPR2020-00777 - Ex. 2008 - 007
`
`

`

`baseline weights from 3,500 and 7,000 pounds; and "long" outriggers are used
`for vehicles with baseline weights from 7,001 to 10,000 pounds. Information on
`NHTSA's titanium outrigger system is documented in [3].
`
`2.3 Tires
`
`All tires must be new, and of the same make, model, size, and DOT
`
`specification of those installed on vehicles when purchased new. Tire inflation
`pressures are to be in accordance with the recommendations indicated on each
`vehicle's identification placard.
`
`2.3.1 Tire Mounting Technique
`
`When mounting tires to the rims used for testing, no tire mounting lubricant
`
`should be used. Lubricant is not used due to uncertainty surrounding the
`occurrences of tire debeading observed during NHTSA's rollover research. To
`eliminate the possibility of tire lubricant contributing to this phenomenon, it should
`not be used. Because no lubricant is used, care must be taken to confirm that
`the tire is fully seated on the wheel rim at the completion of the mounting
`procedure.
`
`2.3.2 Frequency of Tire Changes
`
`To minimize the effects of tire wear on vehicle response and rollover
`
`propensity, rollover research requires frequent tire changes. For each loading
`condition, the following guidelines must be followed:
`
`– One set of tires is to be used for each Slowly Increasing Steer test
`series. Each series is comprised of left and right steer tests.
`
`– Up to two tire sets are to be used for the Fishhook maneuver test
`series. The actual number of tire sets used is dependent on the
`response of each vehicle. The tire change protocol is presented in
`the Fishhook maneuver test procedure (Section 3.2). Note: A tire
`
`-8
`
`Magna - IPR2020-00777 - Ex. 2008 - 008
`
`

`

`change between the completion of the Slowly Increasing Steer
`maneuver and initiation of Fishhook testing is not required provided
`the abbreviated Slowly Increasing Steer procedure described in
`Section 3.1.2 is used. If the abbreviated procedure is not used (i.e.,
`the maneuver is performed such that maximum lateral acceleration is
`achieved), a tire change between the completion of the Slowly
`Increasing Steer maneuver and initiation of Fishhook testing is
`required, as tire wear associated with these tests may potentially
`confound Fishhook test outcome.
`
`2.3.3 Use of Inner Tubes
`
`Fishhook maneuvers have been shown to produce debeading of the outside
`
`front and rear tires. The occurrence of debeading can result in significant
`damage to the test surface. NHTSA research has concluded the easiest, most
`cost effective way to minimize debeading is the use of inner tubes designed for
`radial tires. Inner tubes must be installed prior to any Fishhook test - one inner
`tube for each of the vehicle's tires. Inner tubes should be appropriately sized for
`the test vehicle's tires.
`
`Installation of inner tubes is not required prior to Slowly Increasing Steer
`
`tests, regardless of vehicle or load condition.
`
`2.4 Data Collection
`
`All data is to be sampled at 200 Hz. NHTSA's signal conditioning consists
`
`of amplification, anti-alias filtering, and digitizing. Amplifier gains are selected to
`maximize the signal-to-noise ratio of the digitized data. Filtering is performed
`with two-pole low-pass Butterworth filters with nominal cutoff frequencies
`selected to prevent aliasing. The nominal cutoff frequency is 15 Hz (calculated
`breakpoint frequencies are 18 and 19 Hz for the first and second poles
`respectively).
`
`-9
`
`Magna - IPR2020-00777 - Ex. 2008 - 009
`
`

`

`Data collection is initiated manually by the test driver immediately before the
`
`start of the maneuver or automatically initiated by the "Handwheel Command
`Flag" signal from the steering machine (refer to Section 3.2.4.2.2, Handwheel
`Command Flag).
`
`2.5
`
`Instrumentation
`
`Each test vehicle is to be equipped with sensors, a data acquisition system,
`
`and a programmable steering machine. Equipment location and weight
`specifications are presented in Table A.1 and Fig A.1.
`
`2.5.1 Sensors and Sensor Locations
`
`Table A.2 lists the sensors required by NHTSA's dynamic rollover
`
`propensity test procedure. A brief description of these sensors is provided in this
`section.
`
`2.5.1.1 Handwheel Angle
`
`Handwheel position is measured via an angle encoder integral with the
`
`programmable steering machines.
`
`2.5.1.2 Vehicle Speed
`
`Vehicle speed is measured with a non-contact speed sensor placed at the
`
`center rear of each vehicle. NHTSA has had good experiences with the use of
`Doppler radar based sensors. Sensor outputs are to be transmitted not only to
`the data acquisition system, but also to a dashboard display unit. This allows the
`driver to accurately monitor vehicle speed.
`
`
`
`Table A.2. Recommended Sensor Specifications
`
`-10
`
`Magna - IPR2020-00777 - Ex. 2008 - 010
`
`

`

`Type
`
`Output
`
`Range
`
`Resolution
`
`Accuracy
`
`Multi-Axis Inertial
`Sensing System
`
`Longitudinal,
`Lateral, and
`Vertical
`Acceleration
`Roll, Yaw, and
`Pitch Rate
`
`Accelerometers:
`±2 g
`Angular Rate
`Sensors:
`±100 deg/s
`
`Accelerometers:
`≤10 ug
`Angular Rate
`Sensors:
`≤0.004 deg/s
`
`Accelerometers:
`≤0.05% of full
`range
`Angular Rate
`Sensors: 0.05% of
`full range
`
`Angle Encoder
`
`Handwheel Angle ±800 deg
`
`0.25 deg
`
`±0.25 deg
`
`Ultrasonic
`Distance
`Measuring
`System
`
`Load Cell
`
`Radar Speed
`Sensor
`
`Infrared Distance
`Measuring
`System
`
`Left and Right
`Side Vehicle
`Height
`
`5 - 24 inches
`
`0.01 inches
`
`±0.25% of
`maximum distance
`
`Brake Pedal Force 0 - 300 lbf
`
`N/A
`
`N/A
`
`Vehicle Speed
`
`0.1 - 125 mph
`
`0.009 mph
`
`Wheel Lift
`
`13.75 - 33.5
`inches
`
`0.01 in., short
`range
`0.3 in., long range
`
`±0.25% of full
`scale
`
`±1% of full scale
`
`Flag should
`respond within
`10 ms
`
`Flag should
`respond within 10
`ms
`
`Data Flag
`(Handwheel
`Command Flag)
`
`Pauses in
`commanded
`steering inputs
`
`Data Flag (Roll
`Rate Flag)
`
`Indication of
`± 1.5 deg/s roll
`rate
`
`2.5.1.3 Chassis Dynamics
`
`N/A
`
`N/A
`
`0 - 10 V
`
`0 - 10 V
`
`
`
`A multi-axis inertial sensing system is used to measure linear accelerations
`
`and roll, pitch, and yaw angular rates. The position of the multi-axis inertial
`sensing system must be accurately measured relative to the C.G. of the vehicle
`in the Nominal Load and Multi-Passenger Configurations. These data are
`required to translate the motion of the vehicle at the measured location to that
`which occurred at the actual C.G to remove roll, pitch, and yaw effects. NHTSA
`uses an independent laboratory to measure the C.G. of its' test vehicles.
`
`-11
`
`Magna - IPR2020-00777 - Ex. 2008 - 011
`
`

`

`The following equations are used to correct the accelerometer data in post-
`
`processing. They were derived from equations of general relative acceleration
`for a translating reference frame and use the SAE Convention for Vehicle
`Dynamics Coordinate Systems. The coordinate transformations are:
`
`(
`)
`2
`′+′
`x
`ΨΘ
`(
`)
`′
`′′+′
`x
`ΨΦΘ
`
`x
`
`′′
`corrected
`
`′′=
`x
`accel
`
`−
`
`2
`
`+
`
`disp
`
`y
`
`′′
`corrected
`
`′′=
`y
`accel
`
`+
`
`disp
`
`−
`
`(
`′
`′′−′
`ΨΦΘ
`(
`2
`′−′
`ΨΦ
`
`2
`
`′′
`z
`corrected
`Where,
`
`′′=
`z
`accel
`
`−
`
`(
`′
`′′−′
`ΘΦΨ
`
`)
`x
`
`disp
`
`+
`
`(
`′
`′′−′
`ΦΘΨ
`
`)
`
`y
`
`disp
`
`−
`
`)
`y
`)
`y
`
`(
`′
`′′+′
`ΘΦΨ
`
`+
`
`) disp
`z
`
`disp
`
`disp
`
`(
`) disp
`′
`′′−′
`z
`ΦΦΨ
`) disp
`z
`
`2
`
`+
`(
`2
`′+′
`ΘΦ
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`z ′′
`y ′′
`x ′′
` = longitudinal, lateral, and vertical
`, and corrected
`,
`corrected
`corrected
`accelerations, respectively, at the vehicle's center of gravity
`
`z ′′
`y ′′
`x ′′
` = longitudinal, lateral, and vertical accelerations,
`, and accel
`,
`accel
`accel
`respectively, at the accelerometer location
`
`z
`y
`x
` = longitudinal, lateral, and vertical displacements,
`, and disp
`, disp
`disp
`respectively, of the center of gravity with respect to the accelerometer
`location
`
`Φ′ and Φ′′ = roll rate and roll acceleration, respectively
`
`Θ′ and Θ′′ = pitch rate and pitch acceleration, respectively
`
` Ψ′ and Ψ′′ = yaw rate and yaw acceleration, respectively
`
`NHTSA does not use inertial stabilized accelerometers for this test procedure.
`Therefore, lateral acceleration must be corrected for vehicle roll angle during
`data post processing. This is discussed in Section 4.12.
`
`2.5.1.4 Roll Angle
`
`-12
`
`Magna - IPR2020-00777 - Ex. 2008 - 012
`
`

`

`An ultrasonic distance measurement system is used to collect left and right
`
`side vertical displacements for the purpose of calculating vehicle roll angle. One
`ultrasonic ranging module is mounted on each side of a vehicle, and is positioned
`at the longitudinal center of gravity. With these data, roll angle is calculated
`during post-processing using trigonometry.
`
`2.5.1.5 Wheel Lift
`
`Wheel lift is measured individually with two height sensors attached to
`
`spindles installed at the wheel. Using trigonometry, the output of the two
`sensors can be used to resolve the camber angle of the wheel, and remove its
`influence from the uncorrected height sensor output. Information on NHTSA's
`wheel lift measurement system is documented in [4]. The initial testing shall be
`conducted without the use of the wheel lift instrumentation. In the event that a
`tip-up is observed, the contractor shall re-run the test with the use of wheel lift
`instrumentation.
`
`2.5.1.6 Brake Application
`
`Brake pedal force is measured with a load cell transducer attached to the
`
`face of the brake pedal. While brake pedal force is not explicitly required by this
`test procedure, it is important to monitor the driver's braking activity during
`testing. No test included in this procedure requires brake application. If the
`driver applies force to the brake pedal before completion of a test, that test is not
`valid, and should not be considered in further analyses.
`
`2.5.2 Additional Mnemonics
`
`2.5.2.1 Handwheel Command Flag
`
`
`
`Refer to Section 3.2.4.2.2, Handwheel Command Flag.
`
`2.5.2.2 Roll Rate Flag
`
`-13
`
`Magna - IPR2020-00777 - Ex. 2008 - 013
`
`

`

`
`
`Refer to Section 3.2.4.2.3, Roll Rate Flag.
`
`2.6 Steering Machine
`
`A programmable steering machine is used to generate handwheel steering
`
`inputs for all test maneuvers. The machine must provide at least 35 lb-ft of
`torque at a handwheel rate of 720 deg/sec, be able to move each vehicle's
`steering system through its full range, and accept angular rate sensor feedback
`input for roll rate-induced steering reversals (refer to Section 3.2.4). It is
`recommended that the steering machine be capable of initiating steering
`programs at a preset road speed, and have the convenience of changing the
`steering program during test sessions.
`
`3.0 TEST MANEUVERS
`
`3.1 Slowly Increasing Steer
`
`The Slowly Increasing Steer maneuver is used to characterize the lateral
`
`dynamics of each vehicle, and is based on the "Constant Speed, Variable Steer"
`test defined in SAE J266 [5]. The maneuver is used to determine the steering
`that produces a lateral acceleration of 0.3 g. This handwheel angle is used to
`define the magnitude of steering to be used for the NHTSA Fishhook maneuver.
`
`3.1.1 Maneuver Description (Option #1)
`
`To begin this maneuver, the vehicle is driven in a straight line at 50 mph.
`
`The driver must attempt to maintain this speed during and briefly after the
`steering is input using smooth throttle modulation. At time zero, handwheel
`position is linearly increased from zero to 270 degrees at a rate of 13.5 degrees
`per second. Hand wheel position is held constant at 270 degrees for two
`seconds, after which the maneuver is concluded. The handwheel is then
`returned to zero as a convenience to the driver. The maneuver is performed
`three times to the left and three times to the right for each load configuration.
`
`-14
`
`Magna - IPR2020-00777 - Ex. 2008 - 014
`
`

`

`Figure A.6 presents a description of the handwheel angles to be used during
`Slowly Increasing Steer, Option #1 tests.
`
`3.1.2. Maneuver Description (Option #2, Preferred)
`
`Historically, NHTSA has used Slowly Increasing Steer tests to measure
`
`linear range and maximum quasi steady state lateral acceleration. While
`maximum lateral acceleration data is interesting, it is not a required metric when
`determining a vehicles NCAP rollover resistance rating. For this reason, NHTSA
`recommends use of an "abbreviated" Slowly Increasing Steer maneuver. The
`handwheel angles used in this abbreviated procedure only steer the vehicle
`enough to assess its linear range lateral acceleration performance.
`
`To determine the most appropriate Slowly Increasing Steer handwheel
`
`angle for a given vehicle, a preliminary left steer test is performed. The test
`speed during this test was held constant at 50 mph via throttle modulation, and
`the steering input ranged from 0 to 30 degrees, applied at 13.5 degrees per
`second. The magnitude of this input was selected because it was believed to be
`capable of producing a steady state lateral acceleration within the linear range for
`any light vehicle. Using the ratio of steady state handwheel position and lateral
`acceleration established by this test, the maximum steering input for the
`abbreviated Slowly Increasing Steer test was derived using the below equation:
`
`Equation 3.1
`
`
`
`
`
`
`
`
`
` degrees 30
`a
`
`y,
` degrees 30
`
`
`
`=
`
`∂
`SIS
`55.0
`
`g
`
`
`
`where,
`
`
`
`
`
`
`
`
`
` 30,ya degrees
`
`
`
`
`
`is the raw lateral acceleration produced with a constant
`handwheel angle of 30 degrees during a test performed at
`50 mph
`
`SIS∂
`
`
`
`
`
`
`
`is the steering input that, if the relationship of handwheel
`angle and lateral acceleration was linear, would produce a
`
`-15
`
`Magna - IPR2020-00777 - Ex. 2008 - 015
`
`

`

`lateral acceleration of 0.55 g during a test performed at 50
`mph
`
` 30,ya degrees
`Note:
` is "raw" data, not corrected for the effects of roll, pitch, and yaw.
`
`NHTSA acknowledges the relationship of handwheel angle and corrected lateral
`acceleration data is often not linear at 0.55 g. However, previously collected data
`indicates the magnitude of raw 0.55 g acceleration data is typically reduced by
`approximately 9.6 percent to 0.497 g, when corrected for roll, pitch, and yaw, just
`outside of the linear range for most vehicles. Removing the effect of
`accelerometer offset (error due to the accelerometer not being positioned at the
`vehicle's actual center of gravity) typically reduces the magnitude of these data
`by an additional 0.07 percent. The importance of Equation 3.1 is that it simply
`provides experimenters with a direct, "in-the-field" way of determining an
`appropriate steering input for which to proceed with further tests for a given
`vehicle.
`
`Figure A.7 presents a description of the handwheel angles to be used
`
`during the abbreviated Slowly Increasing Steer, Option #2 tests.
`
`3.1.3 Measured Parameters
`
`Analyses of Slowly Increasing Steer tests output overall average handwheel
`
`position at a specified lateral acceleration
`
`When lateral acceleration data collected during Slowly Increasing Steer
`
`tests is plotted with respect to time, a first order polynomial best-fit line accurately
`describes the data from 0.1 to 0.375 g. NHTSA defines this as the linear range
`of the lateral acceleration response. A simple linear regression is used to
`determine the best-fit line, as shown in Figs I.8 and 1.9.
`
`Using the slope of the best-fit line, the average of handwheel position at 0.3
`
`g is calculated using data from each of the six Slowly Increasing Steer tests
`performed for each vehicle. This average handwheel position is used to
`
`-16
`
`Magna - IPR2020-00777 - Ex. 2008 - 016
`
`

`

`calculate NHTSA Fishhook maneuver steering inputs, as described in Section
`3.2.
`
`3.2 NHTSA Fishhook Maneuver
`
`3.2.1 Maneuver Overview
`
`To begin the maneuver, the vehicle is driven in a straight line at a speed
`
`slightly greater than the desired entrance speed. The driver releases the throttle,
`and when at the target speed, initiates the handwheel commands described in
`Fig A.10 using a programmable steering machine. Following completion of the
`countersteer, handwheel position is maintained for three seconds. As a
`convenience to the test driver, the handwheel is then returned to zero.
`
`Each Fishhook maneuver test series contains two sequences (with
`
`exceptions noted in the following sections): tests performed with left-right
`steering (first sequence), and tests performed with right-left steering (second
`sequence). The sequence of left-right tests always precedes those performed
`with right-left steering.
`
`3.2.2 Default Procedure
`
`Fishhook maneuver handwheel angles are calculated with lateral
`
`acceleration and handwheel angle data (d) collected during a series of six Slowly
`Increasing Steer tests (a total of three left-steer and three-right steer tests are
`performed). For each Slowly Increasing Steer test, a linear regression line is
`fitted to the lateral acceleration data from 0.1 to 0.375 g. Using the slopes of
`these regression lines, the handwheel angles at 0.3 g are determined for each
`
`individual test ( )g.30δ
`. The six handwheel angles are then averaged to produce
`an overall value (
`)
` overall ,30 g.δ
`
`.
`
`
`
`
`-17
`
`Magna - IPR2020-00777 - Ex. 2008 - 017
`
`

`

` g overall ,3.0
`
`
`
` left ,3.0 g
`
` g left ,3.0
`
`(
`δ
`=
`δ
`+
`δ
`+
`δ
`+
`δ
`+
`δ
`δ
`+
`( )
`( )
`( )
`( )
`( )
`
`
`
` g right ,3.0
`
` g left ,3.0
`
`
`
`1
`
`2
`
`
`3
`1
`
`
`2
`The Fishhook maneuver steering angles are calculated by multiplying
`by a steering scalar (SS). The default steering scalar is 6.5.
`
` g right ,3.0
`
` g right ,3.0
`
`) 6/
`( )
`3
`
` overall ,30 g.δ
`
`
`
`
`δ
`efault)Fishhook(d
`
`
`
`=
`
`5.6
`
`×
`
`
`3.2.2.1 Maneuver Entrance Speed
`
`gδ overall ,3.0
`
`
`
`
`
`For the sake of driver safety, and as a final step in the tire scrub-in
`
`procedure, each Default Procedure sequence begins with a Maneuver Entrance
`Speed (MES) equal to 35 mph. The MES is measured at the initiation of the first
`steering ramp, and is increased until a termination condition is satisfied. The
`order of MES for a sequence is, in mph: 35, 40, 45, 47.5, and 50. For each test
`run, the actual MES must be within 1 mph of the target MES.
`
`Note: NHTSA's experience with the Fishhook maneuver indicates that an
`
`incremental increase in MES of 5 mph, up to 45 mph, minimizes tire wear without
`compromising test driver safety. However, when a MES greater than 45 mph is
`used, the severity of the responses produced with some vehicles can increase
`substantially from that observed at lesser entrance speeds. This is especially
`true if a vehicle has a propensity to oscillate in roll, and/or is able to produce two-
`wheel lift slightly less than NHTSA's threshold criterion of two inches. In some of
`these cases, the driver and/or experimenter may not be comfortable with a final 5
`mph upwards increment in MES, and might, for the sake of driver safety, deviate
`from a test procedure that requires it. Generally speaking, such a deviation
`typically involves the experimenter's use of a more gradual 2.5 mph increase in
`MES.
`
`To promote driver safety while also eliminating inconsistencies in the way
`
`NHTSA's Fishhook maneuvers are performed, the test procedure requires a MES
`increment equal to 2.5 mph be used above 45 mph if a test performed at 45 mph
`does not produce two-wheel lift, regardless of the vehicle being evaluated.
`
`3.2.2.2 Outrigger Contact
`
`-18
`
`Magna - IPR2020-00777 - Ex. 2008 - 018
`
`

`

`If either safety outrigger contacts the pavement without two-wheel lift during
`
`a Fishhook maneuver test run, the affected outrigger is raised 0.75 inches and
`the test is repeated at the same MES. If both safety outriggers contact the
`pavement without two-wheel lift, both outriggers are raised 0.75 inches and the
`test is repeated at the same MES.
`
`3.2.2.3 Termination and Conclusion Conditions
`
`A test sequence is terminated if the MES capable of producing two-wheel lift
`
`is observed and the MES is 45 mph or lower. If two-wheel lift is observed during
`a left-right sequence at 45 mph or lower, the [entire] series is terminated. If no
`two-wheel lift is observed during a left-right sequence, right-left tests are
`performed. If two-wheel lift is observed during a right-left sequence performed
`with a MES of 45 mph or lower, the test series is terminated.
`
`If the MES capable of producing two-wheel lift during a left-right or right-left
`
`sequence is 47.5 mph or higher, a new set of tires is installed on the vehicle and
`the procedure described in Section 3.2.3.1 is implemented.
`
`A test series is terminated if rim-to-pavement contact or tire debeading is
`
`observed during any test performed with either test sequence.
`
`A test series is deemed complete if both test sequences within a given
`
`series have been performed at the maximum maneuver entrance speed without
`two-wheel lift, rim-to-pavement contact, tire debeading, or outrigger-to-pavement
`contact. If the Default Procedure is completed without encountering a
`termination condition, Supplemental Procedure Part 2, described in Section
`3.2.3.2, is implemented.
`
`The flowchart presented in Fig A.11 describes the sequence of events for
`
`the Default Test Series.
`
`3.2.3 Supplemental Procedures
`
`-19
`
`Magna - IPR2020-00777 - Ex. 2008 - 019
`
`

`

`
`Note: If the results of the Default Test Series require the implementation of
`the Supplemental Procedure Part 1, neither Supplemental Procedure Part 2 nor
`Part 3 is used.
`
`
`Note: Depending of the response of test vehicles to elements of the
`Fishhook maneuver protocol, Supplemental Procedure, Parts 1, 2, and 3 may
`require a change in the steering scalar. The steering machine used by NHTSA
`has the capability for making such changes in vehicles during test sessions via
`selection of a pre-programmed steering schedule and the adjustment of overall
`steering angles.
`
`3.2.3.1 Supplemental Procedure Part 1
`
`Following the tire scrub-in procedure outlined in Section 4.6, tests are
`
`, as explained in
`performed with handwheel angles equal to
`δ
`efault)Fishhook(d
`
`Section 3.2.2. The steering combination (i.e., either left-right or right-left) that
`produced two-wheel lift in the Default Test Series is used. The first test is to be
`performed at a MES of 35 mph. This test is performed to ensure any mold sheen
`remaining from the tire break-in procedure has been removed from the tires. The
`second test is to be performed at the MES at which two-wheel lift had been
`previously o