Synthesized Disturbance Observer for Vehicle Lateral Disturbance Rejection

Fast disturbance detection and compensation play an important role in vehicle steering control system. Disturbance observer (DOB) is an effective technique to compensate for the disturbance. However, the design procedure of the DOB requires a stable inverse of the plant and an additional
$Q$
filter to guarantee the stability and the robustness to plant uncertainties. Therefore, the design procedure is challenging for the multi-input-multi-output (MIMO) systems, which limits DOB's application in the vehicle steering system. This paper proposes a systematic DOB design framework for the vehicle steering control system. The framework converts the DOB design problem into an equivalent H-infinity optimal control design problem, which is then transformed into a convex optimization problem and can be solved efficiently thereafter. The framework is based on the H-infinity synthesis methodology, which can be easily exploited to include the system uncertainties based on mu synthesis in robust control theory. Complete design procedures and comprehensive simulation analysis are included in this paper. The simulation results validate that the designed DOB can detect and compensate for the disturbance effectively to guarantee the vehicle steering performance.