Abstract
The influence of the active front steering system on the driver’s intention and the trade-off between the robustness and the performance of the active front steering controller have not been adequately addressed by current research studies. A new robust control method based on the normalized left coprime factorization model including uncertainty and perturbations is introduced, and the robustness of this method against high speeds and variations in the cornering stiffness without changing the intention of the driver is guaranteed by the design of the feedforward controller and the feedback controller. A single-step method is adopted to solve the feedforward robust controller and the feedback robust controller. The resulting controllers obtained by the proposed robust control method have a simple structure and do not require online optimization. Furthermore, simulations of the double-lane-change manoeuvre and of braking on a split-μ road are conducted to compare the performance and the stability of the new robust control method with those of the proportional–integral–derivative controller and the standard H∞ controller. Simulation results show that, in comparison with the other two control methods, the established new robust control method can enhance the vehicle stability and handling, and the tracking rapidity is improved by the introduction of feedforward control so that the active steering intervention does not affect the driver’s intention, regardless of the external interferences or emergency evasive manoeuvres.
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