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### Hi Angie, Mjlls Alberta E

Heggs Angela

FW: Materials from March 10 Meeting

Wednesday, March 25, 2015 1:59:49 PM



### cpsc J Tum Djscussjon updated pdf



### cesc Tilt Table pdf

CfSC Smooth Tire Comparjsoo pdf

Handling Metrjc

- 03-10

- 15 pdf



### Please include the attached documents with the ROV rulemaking comments.



## - - ·- 

## ----- 

# - - ---- From: Borlase, George

Sent: Wednesday, March 25, 2015 1:44 PM

To: Mills, Alberta E.

Subject: FW: Materials from March 10 Meeting



### Alberta,

Would you please make sure these are entered in the public record as part of the open

rulemaking docket on ROV 

### s? They are the presentations from the March 1oth 

### open public

meeting with Polaris, Inc.

Sincerely,

George

George A. Borlase, Ph.D., P.E.

Assistant Executive Director for Hazard Identification and Reduction

U.S. Consumer Product Safety Commission

4330 East- West Highway

Bethesda, MD 20814

Phone: (301) 504-7622

Cell: (240)429-5868

"These comments are those of the CPSC staff, and have not been reviewed or approved by,

and may not necessarily reflect the views of, the Commission. "

From: Paul Vitrano [ maj!to:Pau! Vitraoo@polarjs com ]

Sent: Friday, March 20, 2015 3:32 PM

To: Borlase, George

Subject: Materials from March 10 Meeting



### George,

Thanks again to you and the staff for meeting with my colleagues and me on March 10 to review

Polaris' dynamic stability and handling testing and development. Attached are .pdfs of the two slide

deck presentations.

In addition, attached are .pdfs of two other slides decks covering subjects discussed during themeeting:

1. Comparative Metrics: J-Turn and Tilt Table Correlation

2. Constant Radius Test Results Comparing On-Road vs. Off-Road Tires

We will provide additional information concerning our proposed handling metric as it is available.

Please do not hesitate to contact me if you have questions.

Paul

Paul C. Vitrano

VP, Global Government Relations

Polaris Industries Inc.

1999 K Street, N.W., Box 9

Washington, D.C. 20006

202-714-3386

paul.yjtrano@polarjs com



### CONFIDENTIAL: The information contained in this email communication is confidential

information intended only for the use of the addressee. Unauthorized use, disclosure or

copying of this communication is strictly prohibited and may be unlawful. If you have

received this communication in error, please notify us immediately by return email and

destroy all copies of this comtnunication, including all attachments.Attorney

- Client Privileged and Confidential 

# Off Road Vehicle

Division



# J

- Turn DiscussionAttorney

- Client Privileged and Confidential 

# Off Road Vehicle

Division



# From safecar.gov Website

2 

# NHTSA Rollover Definitions

TRIPPED ROLLOVERS

NHTSA data show that 95% of single

- vehicle rollovers are tripped

. This happens when a vehicle leaves the roadway and slides

sideways , digging its tires into soft soil or striking an object such as a curb or guardrail. The high tripping force applied to the tir es

in these situations can cause the vehicle to roll over. UN

- TRIPPED

Un

- tripped rollovers are less common than tripped

rollovers, occurring less than 5% of the time, and

mostly to top

- heavy vehicles. Instead of an object

serving as a tripping mechanism, un

- tripped rollovers

usually occur during high

- speed collision avoidance

maneuvers.Attorney

- Client Privileged and Confidential 

# Off Road Vehicle

Division



# NPR Ay Requirement Can Not Prevent Tripping Rollovers

3 

# Off Road Vehicle Tripping Condition

Environment

Sand

Soil Berm

Rock

Tree Stump

Incline Resistance Center of Gravity

Sliding Force Moment

Of Inertia Force = Mass times Acceleration (Spike Load Condition)

Can easily exceed 2G Tipping Force



# Off Road driving conditions can result in a tripping condition

http:// www.safercar.gov/Vehicle+Shoppers/Rollover/Types+of+RolloversAttorney

- Client Privileged and Confidential 

# Off Road Vehicle

Division



# Video shown at half speed

– actually traveling 25mph

4 

# Sand J

- Turn VideoAttorney

- Client Privileged and Confidential 

# Off Road Vehicle

Division



# Off

- road behaviors can vary greatly from on

- road

– unintended consequences

5 

# Off

- Road Testing

Notes:

1) On pavement, the locked differential is oversteer and the

open differential is understeer

2) In sand and gravel, the understeered vehicle rolled much

easier than the oversteered vehicleAttorney

- Client Privileged and Confidential 

# Off Road Vehicle

Division



# Off

- road behaviors can vary greatly from on

- road

– unintended consequences

6 

# Off

- Road Testing

Notes:

1) On pavement, the locked differential is oversteer and the open

differential is understeer

2) As the surface roughness increased, less steering angle was 

# required and the differential position had less effectAttorney

- Client Privileged and Confidential 

# Off Road Vehicle

Division



# Sliding Begins Well Below 0.7 G, Tripping Occurs Well Above 0.7G

7 

# Lateral Acceleration Comparison

Sand

(Peak Ay @ 1.1) Gravel

(Peak Ay @ 0.9) Pavement

(Peak Ay @ .72)



# All runs shown ended in roll:

• Off

- road runs begin sliding at less than 0.3G and can reach lateral accelerations well above

1.0

• Spikes are noticeable of the tire tripping/skipping over the ground



# • Once the vehicle begins sliding, well below 0.3G, it really doesn’t matter what its Ay on

pavement is because it will trip and spike well above that value 0.7G 0.7G

0.7G

Tire Slip

Tire Slip Tire SlipAttorney

- Client Privileged and Confidential 

# Off Road Vehicle

Division



# Sliding Begins Well Below 0.7 G, Tripping Occurs Well Above 0.7G

8 

# Lateral Acceleration Comparison

Plowed Dirt

(Peak Ay @ 0.96) Rough Grass

(Peak Ay @ 0.87)

0.7G 0.7G 

# Pavement

(Peak Ay @ .72)

0.7G

Tire Slip



# All runs shown ended in roll:

• Off

- road runs begin sliding at less than 0.3G and can reach lateral accelerations well above

1.0

• Spikes are noticeable of the tire tripping/skipping over the ground



# • Once the vehicle begins sliding, well below 0.3G, it really doesn’t matter what its Ay on

pavement is because it will trip and spike well above that value Tire Slip Tire SlipAttorney

- Client Privileged and Confidential 

# Off Road Vehicle

Division



# Steer input on Pavement Is A Better Pass/Fail Metric

9 

# Vast majority of Off

- Road rollovers are tripped

On

- Road J

- Turn does not predict tripped rollover

resistance

Off

- road terrain causes tires to slip well below 0.7g,

proposed threshold is not connected to the terrain failure

limit

Once tires begin to slip, a tripped rollover is highly likely



# Lateral acceleration at trip is well above .7g



# Steer input at roll consistently higher off road vs on

pavement



# Focus vehicle designs to increase slip resistance &

improve handling predictability 

# SummaryAttorney

- Client Privileged and Confidential 

# Off Road Vehicle

Division



# Comparative Metrics: J

- Turn

and Tilt Table CorrelationAttorney

- Client Privileged and Confidential 

# Off Road Vehicle

Division



# TTA Hang Tag Would Provide Comparable Comparison of Vehicles

2 

# Correlation: J

- Turn Ay and TTA

ReturnAttorney

- Client Privileged and Confidential 

# Off Road Vehicle

Division



# Constant Radius Test



# Results Comparing On

Road vs. Off

- Road Tires

3/12/15Attorney

- Client Privileged and Confidential 

# Off Road Vehicle

Division

2 

# Compare data from the same vehicle model using different tires

• Steering Wheel Input Plots

• Lateral Acceleration Plots

• Combined Understeer Plots



# Vehicle: 2015 Polaris RZR 900 (locked differential) used for all tests 

# Objective

OEM Tire

Carlise PXT

26 ” OD; 10

- 12 psi Automotive Tire

Kingstar Centum SK72

26 ” OD; 10

- 12 psi Racing Slick Tire

Hoosier

22” OD; 10

- 12 psiAttorney

- Client Privileged and Confidential 

# Off Road Vehicle

Division



# Steering input improves slightly with smoother tires

3 

# Unfiltered Steering Wheel Input

OEM Tire

Carlise PXT

26 ” OD; 10

- 12 psi Automotive Tire

Kingstar Centum SK72

26 ” OD; 10

- 12 psi Racing Slick Tire

Hoosier

22” OD; 10

- 12 psi

Max

Fluctuation

~14 0 Max

Fluctuation

~7 0 Max

Fluctuation

~10 0Attorney

- Client Privileged and Confidential 

# Off Road Vehicle

Division



# A fter filtering, lateral acceleration is still noisy

4 

# 2Hz Filtered Lateral Acceleration Plots

OEM Tire

Carlise PXT

26 ” OD; 10

- 12 psi Automotive Tire

Kingstar Centum SK72

26 ” OD; 10

- 12 psi Racing Slick Tire

Hoosier

22” OD; 10

- 12 psi



# 2Hz

6 Hz As the tires get smoother, lateral acceleration increases and noise decreasesAttorney

- Client Privileged and Confidential 

# Off Road Vehicle

Division



# Even with smooth tires and filtering, understeer plots are not desirable

5 

# Filtered Understeer Plots

2Hz

6 Hz OEM Tire

Carlise PXT

26 ” OD; 10

- 12 psi Automotive Tire

Kingstar Centum SK72

26 ” OD; 10

- 12 psi Racing Slick Tire

Hoosier

22” OD; 10

- 12 psi



# As the tires get smoother, the understeer plot is less chaoticAttorney

- Client Privileged and Confidential 

# Off Road Vehicle

Division

6 

# Driver input is a source of error and noise. It improves

with smoother tires.

• By using the Polaris proposed fixed steer test, the driver steering

input is completely eliminated, removing that source of error



# Lateral acceleration is also a source of error even after it

has been highly filtered. It improves with smoother tires.

• Lateral acceleration is not an acceptable pass/fail metric for testing

vehicles with off

- road tires 

# SummaryA Handling Quality Metric12A Given: Instability is A Bad ThingInstability implies response is unbounded withtime; invehicle control terms, an uncommanded spinSpins not preferred because they may lead to trippedrollover by presenting the vehicle sideways toobstacles/terrainFour states possible for systems generally[1,2]:Asymptotic StabilityNeutral StabilityDivergent InstabilityOscillatory Instability[1] Fundamentals of Vehicle Dynamics, Gillespie, p402[2] The Multibody Systems Approach to Vehicle Dynamics, Blundell & Harty, p172[3] Race Car Vehicle Dynamics, Milliken & Milliken, p245Understeer/Oversteer and StabilitySAE Understeer guarantees oscillatory asymptoticstability in absence of driver input[3]SAE Oversteer does not predict instability (below)From Fundamentals of Vehicle Dynamics, Gillespie, p403rVehicleDynamics,Milliken&Milliken,p245Divergent Instability Better Surrogate for Tripped Rollover RiskA Given: Instability is A Bad ThingHandling Metric Context3Lateral Acceleration Very NoisyMeasurement noise veryhigh on luggedtires with non-deformable terrainPolynomial Fit ArbitraryVehicle motion is the combination of tireforces divided by reluctance of vehicleto move (mass, inertia)[4]Tires are often represented with socalled “Magic Formula”[5]:There is no good reason to fit apolynomial to the data[4] Newton’s 2ndLaw[5] Tyre Modelling for Use in Vehicle Dynamics Studies, SAE 870421, Bakker, Nyborg,PacejkaDiscerning Turning Point Unsatisfactory ExperimentallyL t l A l ti VNMeasurement Noise> @^ `sin arctan arctanY X D C Bx E Bx Bxa o¬ 1⁄44The Fixed Steer TestExtremely repeatable and requires nospecial facilities other than a consistentsurfaceUnlike constant radius test, it is not atest of the steeringrobot quality, driverskill, etcWhile not directly comparable to othertests (none are directly comparable witheach other), will nevertheless expose avehicle that seeks to spin (“divergent”)Yaw Rate Gives Clean SignalYaw rate is rotation viewed in planData not so susceptible to vibration(magenta) when compared to lateralacceleration (green)Mount location insensitive (identicalreadings anywhere on vehicle)Fixed Steer is Repeatable, Driver-Independent and gives Clean DataThe Fixed Steer TestYaAnother Possible Test ProtocolD t t tibl t ib ti5Yaw Rate is Directly Connected to Lateral AccelerationA Geometric Connection“Non Spin” (aka No-Slip, Steady State) Yaw rate connects to Lateral Acceleration simply:A“geometric” vehicle will have a yaw ratewhich is identical to a neutral steer vehicle[3][3] Race Car Vehicle Dynamics, Milliken & Milliken, p159UδrLA = rUY6Visually a Strong Difference–No Filtering/Processing RequiredDivergent Spin ConditionInstability is shown by a large change in the character(slope) of the plot for a small speed change–it“goesvertical”Detecting Divergence–Fixed Steer Results0.5g HyperbolaMeasuredYaw Ratevs VehicleSpeedExtrapolated line fromon-center fit–5seconds after 2m/s(5 repeats)No Spin ConditionPlotting yaw rate against vehicle speed will show itscharacter compared to a “geometric” vehiclePlotting0.5g*9.81ms-2/Vehicle Speed(ms-1)gives a “0.5gHyperbola”to determine test endConvergent vehicles typically keep a “substantiallyconstant” slope of yawrate with speed7•Divergent response–trace “becomes steep”below0.5g Hyperbola–divergence obvious•Extremely convergent vehicle–trace goeshorizontal•Both vehicles very consistent in fixed steer testProposed Test Shows Large Difference•Divergent responsetrace“becomes steep”Extremely conbecomvergen200ft Fixed Steer–Divergent/ConvergentLeft TurnRight Turn8•Shows loss of path following ability–“path error”(vehicle is less predictable)Shows Both Divergence and Path Error PlainlyShows loss ofpath fof path200ft Fixed Steer–Divergent/Convergent•Note very large increase in yaw rate for 1mphspeed change (~0.5 m/s)Left TurnRight Turn9•Difference still clear - divergent configuration isobvious (vehicle tips onto outriggers on rightturn)•Excellent repeatability alwaysRobust against Test Radius•Difference stcleardivillergconfigurationiscent50ft Fixed Steer–Divergent/Convergent•Convergence remains clear visually at0.5g hyperbolafor 50ft diameter•Path following less compromised at low speedLeft TurnRight Turn10Numerically Robust With Typical Data (20 Vehicle Sample)Plot 5 repeats in each directionFor each repeatFit on-center slopeFit limit slopeAverage on-center slopes betweenrepeatsAverage limit slopes between repeatsEvaluate relationship of averaged limitslope to averaged on-center slopePass-fail criterion?Ratio preferred over arithmetical difference–less sensitive to radiusPlot 5 repeats in each directionSuggested Detail - Provisional0.5g HyperbolaMeasured Yaw Rate vsVehicle SpeedExtrapolated Linefrom on-center fit(5 repeats)Fitted line in limitregion–0.4g to 0.5gFitted line on-center5 seconds of databeyond 2 m/s11Divergent Response Stands Out in Blind, Automated ProcessingSample Metric–Fleet Review (40/50ft)•200ft circle data shows aneven stronger response -ratio of13.8:1(Vehicle 2)•100ft circle expected to besomewhere between thetwo•100ft probably reflects agood compromisebetween space requiredand quality of results•All vehicles convergeexcept Vehicle 2 (spins)•Not all vehicles areundersteer0123412•Test end detection–characteristic goesthrough 0.55g hyperbola or significantdecelerationProcess Automates Well•Test end detectioncharacteristic gristicProcess Automation•Limit identification–0.5g Hyperbolacrossing or maximum inferred LateralAcceleration (some vehicles don’t make0.5g)•Fit window controllable–uses 0.1g inexamples so farTest end autodetectedWllexamples sofar13100ft Data ComparisonExpand Vehicle seteg HistoricTest robustness of processingRefine Pass/Fail criteriaFormalize ProcessReceive Inputs from othersEarly Promise Needs Verification & Formalization100ft D t CNext Steps14Method developed on first principles/best-practicesBetter Surrogate for Tripped Rollover RiskRepeatable methods with minimal test errorsDrives predictable vehicle handling designsDiscriminates and identifies unpredictable behaviorsSuperior Alternative to Understeer BiasM th d dlSummary15•What other signatures can the data show?•Fails to reach 0.5g•Convergent oversteerOther Numerical Measures of Interestto Manufacturers are Possible•What other signatures can the datashow?Broad Picture of Vehicle•Lack of symmetry left-to-right“Club-like” thickening of dataassociated with tire saturation16•Vehicle 1Appendix–Real Vehicle Data–50ft•Vehicle 1Appendix–Real Vehicle Data–50ft•Vehicle 217•Vehicle 3Appendix–Real Vehicle Data–50ft•Vehicle 3Appendix–Real Vehicle Data–50ft•Vehicle 418•Vehicle 5Appendix–Real Vehicle Data–50ft•Vehicle 5Appendix–Real Vehicle Data–50ft•Vehicle 619•Vehicle 7Appendix–Real Vehicle Data–50ft•Vehicle 7Appendix–Real Vehicle Data–50ft•Vehicle 820•Vehicle 9Appendix–Real Vehicle Data–50ft•Vehicle 9Appendix–Real Vehicle Data–50ft•Vehicle 1021•Vehicle 11Appendix–Real Vehicle Data–50ft•Vehicle 11Appendix–Real Vehicle Data–50ft•Vehicle 1222Appendix–Real Vehicle Data–50ftAppendix–Real Vehicle Data–50ft•Summary•Ratio and Delta measurestell the same story(ratio plot shown)•All vehicles converge except Vehicle 2