Global and local chassis control based on load sensing

Modern cars are equipped with an increasing number of active systems in order to help the driver, e.g. to better deal with unexpected changes in the vehicle dynamics. To improve the global vehicle dynamics, comfort and handling, coordination between traditionally stand-alone active systems is required. This demands for a global chassis controller. Thanks to the use of tyre force sensors, the controller proposed in this paper is structured on two layers which simplify the implementation and the computation. The top layer deals with the global control and the force allocation. Thanks to the structure, the nonlinearities and uncertainties of the tyre do not appear in this layer and the allocation can be treated as a convex optimization problem. The solution to this problem taking tyre friction constraints into account is provided by a hybrid dynamical system. The bottom layer features 4 independent local tyre controllers. These ensure, in a robust manner, that the allocated forces are realised. A simulation example shows the performance of the method during a split-mu braking manoeuvre.