Simultaneous optimisation of vehicle parameter and control action to examine the validity of handling control assumptions

In this paper a general method is presented for optimising system parameters and inputs. The Generalised Optimal Control technique involves iterative resimulation of system states, but is applicable to any (smoothly) nonlinear system, and can be operated using non-quadratic cost functions. Here it is applied to find optimal steer and torque inputs for a 2DOF vehicle handling model with a (combined slip) nonlinear tyre model. System parameters for centre of gravity and yaw inertia are simultaneously optimised, and hence the validity of some handling control assumptions – particularly the benefits of zero sideslip – is examined. The results are satisfactory, and they are mainly in keeping with expectation. The method is proven to be effective, though computationally rather expensive!