Design and Calibration of the Jaguar XK Adaptive Cruise Control System. Tim Jagger MathWorks International Automotive Conference 2006

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2 Design and Calibration of the Jaguar XK Adaptive Cruise Control System Tim Jagger MathWorks International Automotive Conference 26

3 JAGUAR XK Page 3

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 4

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.s, 1.4s, 1.8s, 2.2s Driver Selects Cruise Speed Min. 2mph, Max. 112mph Page 5

6 ADAPTIVE CRUISE CONTROL CONTROL APSECTS Page 6

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 25 Initial Calibration Testing May 25 Unexpected Results. Page 7

8 APPROACH XK v S-TYPE 2-2 COMPARISON OF XK v S-TYPE ACC APPROACH TO LEAD VEHICLE TRAVELLING AT 5mph XK shows discontinuous reduction of range rate with range Range Rate m/s S-TYPE shows smooth continuous reduction of range rate with range XK Headway 1 9mph XK Headway 1 1mph S-TYPE Headway 1 9mph S-TYPE Headway 1 1mph Range m Page 8

9 TEST & DEVELOPMENT Results from 1 st 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 9

10 TEST & DEVELOPMENT In reality major development was required Second test period was for validation NOT development Tight timescales & challenging vehicle allocation Page 1

11 ADAPTIVE CRUISE CONTROL VIRTUAL VEHICLE MODEL Page 11

12 MODEL CORRELATION 45 X15 ACC-QA Simulink Model Validation Cruising at Set Speed ACC Host Vehicle Speed m/s Approach 1 Approach 2 Auto-Resume to Set Speed Approach 3 Following Target Vehicle Test - SDV1143 Simulation - CADS-X15-CP39-SDB4-trj4h.mdl Time s Page 12

13 MODEL CORRELATION X15 ACC-QA Simulink Model Validation Residuals approach 1 Residuals approach 2 Residuals approach 3 Range Rate Error m/s Test Vehicle - X15 SDV1143 Simulation - CADS-X15-CP39-SDB4-trj4h.mdl Range m Page 13

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 14

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 1 days ACC Vehicle Simulation was vital for calibration development Page 15

16 SIMULATION PREDICTIONS V TEST RESULTS Range Rate m/s Headway 1 Approach Results. Test v Simulation Predictions 5 Test - 8mph Simulation - 8mph Range Rate m/s Test - 9mph Simulation - 9mph Range Rate m/s Range m Test - 1mph Simulation - 1mph Range m Range Rate m/s Range m Test - 112mph Simulation - 112mph Range m Page 16

17 COMPARISON OF SIMULATION PREDICTIONS WITH PRODUCTION CALIBRATIONS Two calibrations changed from simulation to production Changes based on subjective driver assessment Page 17

18 QUEUE ASSIST Extension of ACC operating range to mph Headway opened significantly at low speeds QA host vehicle unable to track target vehicle accelerating at a moderate rate Filtering of ACC Speed demand introduced significant lag Page 18

19 QUEUE ASSIST 25 Jaguar XK QA Simulation. Acceleration from 5mph to 3mph. 7 Jaguar XK QA Simulation. Acceleration from 5mph to 3mph. 2 Headway 1.1g. Baseline Calibration Lead Car Speed Headway 1.1g. Baseline Calibration Follow Speed Headway 1.1g. Baseline Calibration Vehicle Speed 6 5 Speed m/s 15 1 Range m Headway 1.1g. Baseline Calibration Time s Time s Page 19

20 FILTER CUT-OFF FREQUENCY Use frequency response toolbox to re-calculate filter constant FREQUENCY RESPONSE OF THE FOLLOW SPEED FILTER R44 CALIBRATION. FREQUENCY RESPONSE OF FOLLOW SPEED FILTER - DESIGN Magnitude (db) System: follow_speed_filt_current Frequency (Hz):.151 Magnitude (db): -3 Magnitude (db) System: follow_speed_filt_new_2 Frequency (Hz):.979 Magnitude (db): -3 Phase (deg) -3-6 System: follow_speed_filt_current Frequency (Hz):.15 Phase (deg): FREQUENCY Hz Phase (deg) System: follow_speed_filt_new_2 Frequency (Hz):.979 Phase (deg): Frequency Hz Page 2

21 EFFECT OF NEW FILTER CONSTANT 25 X15 QA Simulation. Headway 1. Acceleration from 5mph to 3mph. Follow Speed Filter 1Hz 7 Jaguar XK QA Simulation. Acceleration from 5mph to 3mph 2 Headway 1.1g CADS Cal. R44. Follow Speed Filter 1Hz Lead Car Speed Headway 1.1g CADS Cal. R44. Follow Speed Filter 1Hz Follow Speed Headway 1.1g CADS Cal. R44. Follow Speed Filter 1Hz Vehicle Speed 6 5 Speed m/s 15 1 Range m Time s 2 1 Baseline Calibration filter Filter 1Hz Time s Page 21

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 3 days to 1 days (Typically 3-4 calibration loops on a vehicle program) Vehicle test time now used for validation - not experimentation Page 22

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