Integrated Chassis Control for Vehicle Stability under Various Road Friction Conditions

This paper presents an integrated chassis control method for vehicle stability under various road friction conditions without information on tire-road friction. For vehicle stability, vehicle with an integrated chassis control needs to cope with the various road friction conditions. One of the chassis control method under various road conditions is to determine and/or limit control inputs based on tire-road friction coefficient. The tire-road friction coefficient, however, is difficult to estimate and still a challenging task. The key idea for the proposed method without the estimation of the tire-road friction coefficient is to analyze and control vehicle states based on a tire slip angle - tire force phase plane, i.e. based on these vehicle responses: tire forces and tire slip angles of front/rear wheels. Based on the phase plane, vehicle instability is detected and the vehicle is controlled to regain the vehicle stability and maneuverability under various road conditions without tire-road friction information. The proposed algorithm consists of two sequential parts: Supervisor part and Chassis control part. The supervisor detects the vehicle instability based on the tire slip angle and tire force phase plane. Based on this information, the supervisor determines a desired slip angle to make the vehicle stable. The chassis control part decides control inputs. From tire slip angle dynamics, a desired yaw moment is calculated to minimize error between the desired slip angle and current vehicle states. For tracking the desired yaw moment, the optimal coordination of the chassis control part optimally allocate the desired yaw moment to each chassis module. The proposed algorithm has been investigated through computer simulations under various road setting. The simulation results show that the proposed control method well copes with maneuver on the various road conditions.