Optimized brake-based control of path lateral deviation for mitigation of secondary collisions

Artikel i vetenskaplig tidskrift, 2011

This paper considers brake-based lateral control of a passenger vehicle, for reducing secondary collision risk following an initial impact in a traffic accident. Since secondary collisions are associated with deviations from the original travel path, the control problem is formulated via brake control sequences that minimize lateral path deviation. Optimal sequences are found not to conform to any simple control mode; sometimes all brakes are released, sometimes all wheels are locked, or the brakes may be applied in differential mode. In general, the optimal strategy combines several such actuation modes, and analysis shows it is related to the utilization of instantaneous vehicle force and moment capacity, indicating that a closed-loop control strategy may be developed based on the real-time estimation of tyre force limits during the post-impact event. Yaw motion control is related to response discontinuity and multiple equilibria found in the optimal response - a small change in initial yaw velocity generates large changes in the ensuing vehicle motion and thus in the aimed equilibrium point of the vehicle's orientation. Overall it is found that braking control strongly influences the post-impact path of the impacted vehicle, and may therefore form the basis of a practical system for avoiding secondary collisions in future traffic accidents.