Objective Ride Testing

Objective Ride Testing

Instrumentation B-Pillar Ax, Ay

Seat Track Az IR Trigger

Steering Column Az

Seat Cushion Az Microphone

Left-Front Strut Az

Zonic Data Acquisition System

Objective Ride Response Data Processing/Metrics Notes • Objective ride measurements are based on seatcushion, seat-track, B-pillar, and steering column vibration measurements.

• Selective filtering and statistical analysis is used to develop Overall Ride Values in 4 frequency areas. • HIGHER VALUES ARE BETTER

Unloaded

Surface: CC2 Objective Ride Value ORV 0.5-4 Hz: 14.50 ORV 4-18 Hz: 2.44 ORV 18-50 Hz: 4.12 ORV 50-100 Hz: 10.98

CC4 A1A A1B A2 Cracked- Cracked Patched Random repaired Asphalt Asphalt Undul Potholes 6.68 2.90 3.53 10.00

17.52 2.48 2.60 9.81

15.52 2.29 2.17 8.05

18.44 2.47 3.36 18.47

11.15 1.62 1.76 9.22

Cleats 30.27 7.93 4.61 8.58

Loaded

Surface: CC2 Objective Ride Value ORV 0.5-4 Hz: 17.30 ORV 4-18 Hz: 2.31 ORV 18-50 Hz: 3.78 ORV 50-100 Hz: 10.56

CC4 A1A A1B A2 Cracked- Cracked Patched Random repaired Asphalt Asphalt Undul Potholes 8.80 3.19 3.61 9.48

20.81 3.03 3.07 9.86

18.75 2.53 2.26 7.48

24.03 3.11 3.57 19.91

13.09 1.76 2.02 9.34

Cleats 32.82 9.98 5.02 9.65

Objective Ride Response

Noise

5 Passes for each speed 20 mph 40 mph 60 mph

50 mph 70 mph Harshness Strips 30 mph 30 mph

30 mph 45 mph 60 mph

Potholes 40 mph

40 mph

40 mph 50 mph

60 mph

Test Surfaces Used

• Defaced Asphalt [5A] • Patched Asphalt [5B] • Cleats (10, 20, 30 mm) [6B] • Smooth Surface [6BA] • Random Undulations [6A] 40 runs / spec x 7 specs = 280 runs 8 channels @ 5120 Hz > 4 Gigabytes of compressed data

Test Speeds: 5 runs @ 45 mph 3 runs @ 25 mph

Subjective Evaluations

Lo Boom

Hi Boom

Cavity Ring

Shake (Uniformity)

Jitters After Shake

Correlated Objective Ride Metrics

Lo Harshness

42 Subjective Ratings

Hi Harshness

+

Tire Specification

4 Gigabytes of Data

Control 6.00 5.50 7.00 7.50 5.50 5.75 5.50 Michelin A DV059P

6.00 5.50 6.00 7.50 5.50 6.00 5.75

B DV060P

6.25 5.75 7.00 7.50 5.00 5.50 5.50

C DV061P

5.75 5.25 6.00 7.50 7.00 6.00 6.00

D DV062P

5.50 5.00 5.50 7.50 7.00 6.00 6.00

E Roads

6.00 5.50 7.00 7.50 7.00 6.00 6.00

Ride Comments Hard but not sharp with good damping Similar butbut much Similar to to Mich Control withlower damping reduced damping performance Slightly softer with equal damping to Mich Control Hard, sharp feel, marginal damping Similar to 61P C but sharper with less damping Harshness and damping same asControl Mich, Boom and Ring better

Metrics & Processing • Time-domain metrics: max, root-mean-square(RMS), root-meanquad(RMQ), vibration dose value(VDV) • Overall ride metrics: objective ride value (ORV), maximum probability density function (maxPDF), RMS of combined vibration channels (Seat, Seat Track, B-Pillar, Steering Column) divided into areas of 1 - 4, 4 - 18, 18 - 50, & 50-100 Hz • Frequency domain metrics: RMQ of power spectrum values within key subjective frequency ranges • Analyzed as averages of runs and as maximum of runs • Linear relationships with subjective ratings checked with correlation coefficients (R2>0.7) and subjective relevance.

138 objective ride metrics per spec

+

6 subjective ratings per spec

18 metrics are noteworthy…

Selected Metrics with High Correlations (R2 > 0.70) Subjective Rating

Test Speed

Surface

High Harshness

0.75

45 mph

Patched Asphalt Cleats Patched Asphalt

STRCMZ MIC Ride metrics

PRMQ_Jitters max RMS 4-18 Hz

0.70 0.81 0.71

Low Harshness

0.75

25 mph

Cleats

STTRKZ LFAZ

PRMQ_Coarse PRMQ_Harsh

0.75 0.79

Jitters After-Shake

1.50

25 mph

Cleats Random Undulations Patched Asphalt Random Undulations Patched Asphalt Patched Asphalt

STTRKZ STRCMZ STRCMZ STRCMZ BPLRX Ride metrics

PRMQ_Boom2 VDV PRMQ_Plush Max PRMQ_Jitters RMS 50-100 Hz

0.81 0.71 0.79 0.85 0.88 0.71

45 mph

Cleats Random Undulations Patched Asphalt

LFAZ MIC BPLRY

PRMQ_Cavity PRMQ_Cavity PRMQ_Cavity

0.87 0.89 0.78

45 mph Cavity Ring

2.00

25 mph

Sensor

Metric

R2

Span

High Boom

0.50

45 mph

Defaced Asphalt

LFAZ

VDV

0.91

Low Boom

0.50

25 mph

Cleats Patched Asphalt Defaced Asphalt

LFAZ BPLRY Ride metrics

PRMQ_RN1 PRMQ_Harsh ORV 18-50 Hz

0.90 0.84 0.91

STRCMZ – Steering Column Acc. Vertical STTRKZ – Seat Track Acc. Vertical BPLRX – B-Pillar Acc. Longitudinal

Mic – Microphone LFAZ – Left Front Spindle Acc. Vertical BPLRY – B-Pillar Acc. Lateral