A new flatness-based control of lateral vehicle dynamics

Abstract

This paper presents a new concept for vehicle dynamics control (VDC). The control of the longitudinal vehicle dynamics is not discussed, since we are assuming that it is much slower and weakly coupled to the lateral and yawing dynamics. The actuators are considered to be the traction and the braking torques of the individual wheels and only the standard sensors of the common VDC system are used. A modular interface to the subordinate wheel control system is provided by choosing the yaw torque as a fictitious control input. The VDC system is designed by means of a two degrees-of-freedom control scheme. It comprises a flatness-based feedforward part and a stabilising feedback part. The reference trajectory generation is introduced for the flat output which is given by the lateral velocity of the vehicle. Thus an advantageous kind of body side-slip angle control is provided with the standard VDC system hardware. Extensive simulation studies show excellent performance of the designed control concept.

Keywords:

• vehicle dynamics control
• differential flatness
• two degrees-of-freedom control
• trajectory generation

Notes

Note that the reference model requires the knowledge of the steer angle δ_f and its time derivatives up to the second order . The steer angle of the front wheel δ_f can be simply calculated out of the measured steering wheel angle . The required time derivatives and can be obtained for example by means of the derivative estimator proposed for example in 26.