BEST, M.C., 2010. Exploring assumptions and requirements for continuous modification of vehicle handling using non-linear optimal control and a new exponential tyre model. IN: Proceedings of the 10th International Symposium on Advanced Vehicle Control (AVEC), Loughborough, UK, 22nd-26th August, pp. 79–84.
An iterative simulation-based nonlinear optimisation technique is used here to explore optimally
controlled behaviour of a large RWD vehicle with rear steer and idealised differential actuators. A
novel tyre model is also introduced, which uses simple analytic functions for separated calculation of
lateral and longitudinal force, with both based on the combined slip and vertical load. By first
considering suitable transient and steady-state targets for the yaw rate, optimal control is simulated
which is effective throughout the lateral acceleration range. Interestingly this can be closely emulated
under stable conditions using PID control of rear steer only, according to the yaw rate target and
without the need for separate lateral velocity control. PID is no longer successful when stabilising
control is considered, so future research will consider an extension to the nonlinear optimisation method
for such cases.