Automated test of the AMG Speedshift DCT control software

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1 Automated test of the AMG Speedshift DCT control software M. Tatar QTronic GmbH, Berlin R. Schaich, T. Breitinger Mercedes-AMG GmbH, Affalterbach 9th International CTI Symposium Berlin, 2010

2 Outline Motivation Principle of the scenario generator Test of AMG Speedshift DCT control software - the AMG Speedshift DCT - the software test setup Results and conclusion

This does not scale well Code size grows faster New processes needed source:

3 Motivation Ever growing complexity of automotive controllers How to validate and test? - do more road tests? - write more test scripts? This does not scale well Code size grows faster New processes needed source: presentation by Hans Adlkofer, Infineon, 2009 Idea - increase degree of automation - generate and evaluate useful test scenarios automatically

Test Weaver scenario generator Idea intelligent

drive the system in difficult situations

4 Test Weaver scenario generator Idea intelligent generation of 1000s of differing test scenarios Testing = playing against (simulated) system active attempt to: - maximize state coverage - drive the system in difficult situations Benefit high coverage low efforts for test specification

Strategy for Test Generation control alarm input vehicle model fault inputs u ECU C code software-in-the loop GOALS find bugs: Change sub-optimal scenarios to generate

5 Strategy for Test Generation control alarm input vehicle model fault inputs u ECU C code software-in-the loop GOALS find bugs: Change sub-optimal scenarios to generate worst-cases state coverage: Drive the system in states that have not been reached before outputs y Test Weaver y reached state alarm state state DB discretized state space test report u

6 TestWeaver - Test Generation Strategy ok alarm! ta u inp fa u lt 2 root inp ut b inp ut a fault 1 input b input a inpu tb input c time t0

7 Virtual Integration Software in the Loop Simulink / TargetLink module.mdl object.obj DCT control SW developer Modelica / Dymola.obj A2L PAR DCM vehicle model Silver Interactive drive of the virtual vehicle

8 SiL and debugging environment

9 DCT with mechanical locking differential

10 Hydraulic unit of the DCT Source: Hart et.al., The function development and application of the DCT in the Mercedes-Benz SLS AMG. VDI-Berichte 2081: Getriebe in Fahrzeugen 2010, pp

11 Drivetrain of the Mercedes-Benz SLS AMG

12 Drivetrain physical simulation model

13 Drivetrain simulation model gear actuators

14 SiL and debugging environment

15 Setup of the software test Simulink / TargetLink module.mdl developer Modelica / Dymola.obj object.obj test report 24 hours vehicle model DCT control SW A2L PAR DCM Silver TestWeaver TestWeaver instruments drive the virtual vehicle generate worst-case scenarios

16 TestWeaver Alarms: correctness / quality Runtime exceptions: division by zero, stack overflow... A2L range monitoring: thousands of TCU signals... Shift durations: average and maximal durations Clutch overheating, overspeeds: engine overspeed or stalled... DCT condition monitoring: > 200 signals, fault codes every problem reported by TestWeaver comes with one or more reproducible examples! Oscillations and unexpected control sequences: repeated up/down shifts, bad fault diagnosis, bad fault reaction Code coverage and system state coverage

17 Example: Problem found and corrected oscillation of target gear - found by TestWeaver - replay in Silver improved control software - run regression test - problem solved

18 Test Results and Conclusion Test of DCT control software generated and analysed over 3000 different driving scenarios, each 45 sec. for every software release systematic test and validation with many usual and many unusual driving conditions Conclusion The presented approach seems extremely well suited for the validation of automotive transmission controllers Necessary complement to other QA measures, test benches, prototype driving Main benefit: - much higher test coverage - feasible work effort

Automated test of the AMG Speedshift DCT control software

presented at 9th International CTI Symposium Innovative Automotive Transmissions, Berlin, 30.11. - 01.12.2010, Berlin, Germany Automated test of the AMG Speedshift DCT control software M. Tatar QTronic