Experimental analysis of a contact patch form of a rolling tire: influence of speed, wheel load, camber and slip angle

Transcription

1 Experimental analysis of a contact patch form of a rolling tire: influence of speed, wheel load, camber and slip angle Dipl.-Ing. Pavel Sarkisov Prof. Dr.-Ing. Günther Prokop Dipl.-Ing. Steffen Drossel Technische Universität Dresden Dr.-Ing. Sergey Popov Bauman Moscow State Technical University 2 nd IAVSD Workshop on Dynamics of Road Vehicles Berlin,

2 Motivation Road traffic safety Driver Assistance Systems Wheel forces Tire behavior ABS / ESP / ASR Torque vectoring Rear axle steering To use as much grip as possible To simulate complex tire behavior To use tire as a sensor Active Rollover Prevention Emergency Steering Assist Stuttgart,

3 Tire as a sensor? Pressure loss To inform driver Tire-mounted sensor Stuttgart,

4 Tire as a sensor? Pressure loss Wear level To inform driver Slip angle Friction potential Aquaplaning Longitudinal/lateral slip Road conditions To improve ADAS control To share further via Car2X Stuttgart, Sources: Audi AG Presskit 08/15; 4

5 A method of friction potential estimation A. Niskanen, A. Tuononen: Tire-road contact condition measurements by an intelligent tire (2017) Grip region Slip region 0 % slip 4 % slip 7 % slip * - notes Acceleration sensor is able to capture grip and slip region lengths Stuttgart,

6 A method of friction potential estimation Slip region Grip region ll gg ll ss Utilized friction potential: Kinematic difference Real: UUUUUU rr = FF xx 2 + FF yy 2 μμff zz Maximum tread deflection Shear deformation Sliding distance Estimated: ll gg UUUUUU ee = 1 2 ll ss + ll gg Intensive braking: 0.5 UUUUUU rr UUUUUU ee 1 Stuttgart,

7 A method of friction potential estimation Grip region ll gg Slip region ll ss Utilized friction potential: Kinematic difference Real: UUUUUU rr = FF xx 2 + FF yy 2 μμff zz Maximum tread deflection Shear deformation Sliding distance Estimated: ll gg UUUUUU ee = 1 2 ll ss + ll gg Intensive braking: 0 UUUUUU rr < 0.5 UUUUUU ee 0.5 Stuttgart,

8 Mission statement Straight run Normal cornering Severe cornering Contact patch shape changes with rolling parameters Sensor notices vibration independently upon slip direction Source: Gim, G. & Choi, Y., 2001 Source: Michelin: Der Reifen: Haftung How many sensors are required for estimation? 2 Can this method be applied for cornering tire? Stuttgart,

9 Mission statement 1 2 How many sensors are required for estimation? Can this method be applied for cornering tire? - To observe contact patch shape depending upon wheel load, speed, camber, slip angle - To develop a simulation model for strain analysis - To analyze method feasibility for lateral slip Stuttgart,

10 Experimental analysis Stuttgart,

11 Measurement method Setup: Measurement: Observation: Seven acceleration sensors in a rolling tire Radial acceleration Contact patch length and position Radial acceleration zz Contact patch length A B C D E F G Contact patch position Contact patch length Stuttgart,

12 Variation of rolling speed A B C D E F G Stuttgart,

13 Variation of rolling speed Stuttgart,

14 Variation of camber angle Stuttgart,

15 Contact patch shape of cambered tire Sensor B 7 kn B Change of patch length up to 25 % per 1 Linear dependence upon camber angle Symmetric patch shape Stuttgart,

16 Variation of slip angle Stuttgart,

17 Contact patch shape of cornering tire Sensor B 73 5 kn B Change of patch length up to 15 % per 1 Nonlinear dependence upon the slip angle Asymmetric patch shape Stuttgart,

18 Model development Picture: Stuttgart,

19 Model development Approach: Focus: Method: To describe physical background of tire behavior Transient handling: Lateral force and aligning torque Decoupling of physical effects Stuttgart,

20 Model validation Lateral force [kn] Y [m] Aligning torque [Nm] Time [s] X [m] Time [s] Measurement Simulation Stuttgart,

21 Model-based analysis Picture: Audi AG, Presskit 08/15 Stuttgart,

22 Feasibility analysis Top view on contact patch Tire excitation: Brake slip, slip angle Utilized friction potential: Real: Estimated: FF 2 2 xx + FF yy μμff zz ll gg 1 2 ll ss + ll gg ll ss ll gg Stuttgart,

23 Feasibility analysis: braking with camber Estimated Real Real potential: FF xx 2 + FF yy 2 μμff zz Estimated potential: ll gg 1 2 ll ss + ll gg Stuttgart,

24 Feasibility analysis: cornering and braking Estimated Real One sensor in the middle of tire provides error of 5 % Length-based estimation for cornering tire is feasible Stuttgart,

25 Sliding speed analysis Sliding speed of cornering tire (3 ) corresponds to sliding speed of braking one (5 %) Stuttgart,

26 Summary Contact patch shape changes with: - camber symmetric shape, linear relation - slip angle asymmetric shape, nonlinear relation Implementation of estimation method: - One acceleration sensor, mounted in the middle plane of the tire, is enough for 5 % estimation error Enhancement of estimation method: - Cornering tire features similar slip region length and sliding speed as braking tire Stuttgart,

27 Thank you for your attention! Supported by TU Dresden Graduate Academy Dresden,