Clarification and Achievement of Theoretical Limitation in Vehicle Dynamics Integrated Management

In this article, vehicle dynamics integrated control algorithm using an on-line non-linear optimization method is proposed for 4-wheel-distributed steering and 4-wheel-distributed traction/ braking systems. The proposed distribution algorithm calculates the magnitude and direction of tire forces, which satisfy constraints corresponding to the target resultant force and moment of the vehicle motion and which minimizes maximum μ rate (=tire force/friction circle) of each tire. Convexity of this problem is shown, so that the global optimality of the convergent solution of the recursive algorithm is guaranteed. This implies that theoretical limited performance of vehicle dynamics integrated control is clarified. The proposed algorithm is based on SQP (Sequential Quadratic Programming) and steepest gradient algorithm. Calculation speed performance of the proposed algorithm is shown in comparison with primal-dual interior-point method, which is representative optimization method. Furthermore, the effect of this vehicle dynamics control is demonstrated by simulation and experiment to compare with various vehicle dynamics integrated control methods.