Design and Calibration of the Jaguar XK · Page 5 ADAPTIVE CRUISE CONTROL THE DRIVER’S PERSPECTIVE • Driver Comfort Feature • Allows Host Vehicle to follow a target vehicle

Design and Calibration of the Jaguar XK Adaptive Cruise Control System

Tim JaggerMathWorks International Automotive Conference 2006

Page 3

JAGUAR XK

Page 4

ADAPTIVE CRUISE CONTROL(ACC) MODEL BASED CALIBRATION

• Adaptive Cruise Control – The Driver’s Perspective

• The Adaptive Cruise Control System – Control Aspects

• Jaguar XK Adaptive Cruise Control System

• Jaguar XK Adaptive Cruise Control Virtual Vehicle Model

• Model Correlation

• Jaguar XK Adaptive Cruise Control Calibration Development

• Queue Assist Development

Page 5

ADAPTIVE CRUISE CONTROL THE DRIVER’S PERSPECTIVE• Driver Comfort Feature

• Allows Host Vehicle to follow a target vehicle

• Automatically Resumes to set speed in absence of target vehicle

• Driver selects headway

• Available Headways

– 1.0s, 1.4s, 1.8s, 2.2s

• Driver Selects Cruise Speed

– Min. 20mph, Max. 112mph

Page 6

ADAPTIVE CRUISE CONTROL CONTROL APSECTS

Page 7

JAGUAR XK ADAPTIVE CRUISE CONTROL

• New Adaptive Cruise Control Algorithms for XK

• New Features

– Queue Assist Algorithms

– Lead Vehicle Acceleration Algorithm (LVA)

• Initial Functional Testing – April 2005

• Initial Calibration Testing – May 2005

• Unexpected Results ….

Page 8

APPROACH XK v S-TYPE

0 20 40 60 80 100 120 140-26

-24

-22

-20

-18

-16

-14

-12

-10

-8

-6

-4

-2

0

2

Range m

Ran

ge R

ate

m/s

COMPARISON OF XK v S-TYPE ACC APPROACH TO LEAD VEHICLE TRAVELLING AT 50mph

XK Headway 1 90mphXK Headway 1 100mphS-TYPE Headway 1 90mphS-TYPE Headway 1 100mph

S-TYPE shows smooth continuous reduction of range rate with range

XK shows discontinuous reduction of range rate with range

Page 9

TEST & DEVELOPMENT

• Results from 1st ACC Test Session

– Harsh Early Brake Intervention

– LVA Algorithm gave unpredictable results

– Generally unrefined ACC Performance

• Expectation was that XK ACC would only need small scale refining

– Developed from ACC3

Page 10

TEST & DEVELOPMENT

• In reality major development was required

• Second test period was for validation NOT development

• Tight timescales & challenging vehicle allocation

Page 11

ADAPTIVE CRUISE CONTROL VIRTUAL VEHICLE MODEL

Page 12

MODEL CORRELATION

0 20 40 60 80 100 12020

25

30

35

40

45

Time s

AC

C H

ost V

ehic

le S

peed

m/s

X150 ACC-QA Simulink Model Validation

Test - SDV1143Simulation - CADS-X150-CP39-SDB4-trj04h.mdl

Approach 1

Approach 2

Auto-Resume to Set Speed

Cruising at Set Speed

Approach 3

Following Target Vehicle

Page 13

MODEL CORRELATION

0 20 40 60 80 100 120-1.5

-1

-0.5

0

0.5

1

1.5

Range m

Ran

ge R

ate

Erro

r m/s

Residuals approach 1Residuals approach 2Residuals approach 3

X150 ACC-QA Simulink Model Validation

Test Vehicle - X150 SDV1143 Simulation - CADS-X150-CP39-SDB4-trj04h.mdl

Page 14

CALIBRATION DEVELOPMENT

• Test Results indicated seven parameters influenced ACC refinement

– Lead Vehicle Acceleration Algorithm (LVA)

– ACC brake gain

– Brake demand slew rate

– Time to collision gain

– Residual Distance

– Coast Deceleration Estimate

– Headway Control Maps

Page 15

CALIBRATION DEVELOPMENT

• Test Matrix of 8 possible ACC configurations

• 4 days per configuration to test on vehicle = 32 days vehicle testing

• Complete test matrix was evaluated by simulation in 10 days

ACC Vehicle Simulation was vital for calibration development

Page 16

SIMULATION PREDICTIONS V TEST RESULTS

0 20 40 60 80 100 120 140-15

-10

-5

0

5

Range m

Ran

ge R

ate

m/s

0 20 40 60 80 100 120 140-20

-15

-10

-5

0

5

Range m

Ran

ge R

ate

m/s

0 20 40 60 80 100 120 140-25

-20

-15

-10

-5

0

5

Range m

Ran

ge R

ate

m/s

0 20 40 60 80 100 120 140-30-25-20-15-10-505

Range m

Ran

ge R

ate

m/s

Test - 90mphSimulation - 90mph




Headway 1 Approach Results. Test v Simulation Predictions

Page 17

COMPARISON OF SIMULATION PREDICTIONS WITH PRODUCTION CALIBRATIONS

• Two calibrations changed from simulation to production

• Changes based on subjective driver assessment

Page 18

QUEUE ASSIST

• Extension of ACC operating range to 0mph

• Headway opened significantly at low speeds

• QA host vehicle unable to track target vehicle accelerating at amoderate rate

• Filtering of ACC Speed demand introduced significant lag

Page 19

QUEUE ASSIST

10 20 30 40 50 60 70 800

5

10

15

20

25

Time s

Spee

d m

/s

Jaguar XK QA Simulation. Acceleration from 5mph to 30mph.

Headway 1 0.1g. Baseline Calibration Lead Car SpeedHeadway 1 0.1g. Baseline Calibration Follow SpeedHeadway 1 0.1g. Baseline Calibration Vehicle Speed

10 20 30 40 50 60 70 800

10

20

30

40

50

60

70

Time s

Ran

ge m

Jaguar XK QA Simulation. Acceleration from 5mph to 30mph.

Headway 1 0.1g. Baseline Calibration

Page 20

FILTER CUT-OFF FREQUENCY

10-2 10-1 100

-60

-30

0

Pha

se (d

eg) System: follow_speed_filt_current

Frequency (Hz): 0.15 Phase (deg): -42

-4

-3

-2

-1

0

Mag

nitu

de (d

B)

System: follow_speed_filt_current Frequency (Hz): 0.151 Magnitude (dB): -3

FREQUENCY RESPONSE OF THE FOLLOW SPEED FILTER R44 CALIBRATION.

FREQUENCY Hz 10-1 100-35

-30

-25

-20

-15

-10

-5

0

Pha

se (d

eg)

System: follow_speed_filt_new_02 Frequency (Hz): 0.979

Phase (deg): -29.9

-5

-4

-3

-2

-1

0

Mag

nitu

de (d

B)

System: follow_speed_filt_new_02 Frequency (Hz): 0.979

Magnitude (dB): -3

FREQUENCY RESPONSE OF FOLLOW SPEED FILTER - DESIGN 02.

Frequency Hz

•Use frequency response toolbox to re-calculate filter constant

Page 21

EFFECT OF NEW FILTER CONSTANT

10 20 30 40 50 60 70 800

10

20

30

40

50

60

70

Time s

Ran

ge m

Jaguar XK QA Simulation. Acceleration from 5mph to 30mph

Baseline Calibration filter cut-off @ 0.15HzFilter cut-off @ 1Hz

10 20 30 40 50 60 700

5

10

15

20

25

Time s

Spee

d m

/s

X150 QA Simulation. Headway 1. Acceleration from 5mph to 30mph. Follow Speed Filter -3db @ 1Hz

Headway 1 0.1g CADS Cal. R44. Follow Speed Filter -3dB @ 1Hz Lead Car SpeedHeadway 1 0.1g CADS Cal. R44. Follow Speed Filter -3dB @ 1Hz Follow SpeedHeadway 1 0.1g CADS Cal. R44. Follow Speed Filter -3dB @ 1Hz Vehicle Speed

Page 22

JAGUAR XK MODEL BASED DESIGN AND CALIBRATION

SUMMARY

• Jaguar XK ACC system modelled in simulink

• ACC Model shows good correlation with test results

• Model was used to develop Jaguar XK ACC Calibrations

• Development time per calibration loop reduced from 30 days to 10 days

(Typically 3 - 4 calibration loops on a vehicle program)

• Vehicle test time now used for validation - not experimentation

Documents

Design and Calibration of the Jaguar XK · Page 5 ADAPTIVE CRUISE CONTROL THE DRIVER’S PERSPECTIVE • Driver Comfort Feature • Allows Host Vehicle to follow a target vehicle