Extension Integrated Control of Electric Vehicles AFS/DYC Based on LQR

A hierarchical integrated control strategy of the active front wheel steering system (AFS) and direct yaw moment control (DYC) was developed to compensate for the active front wheel steering system’s lack of vehicle stability control caused by tire lateral force saturation and minimize the power consumption of the executive system. The upper controller divides the vehicle operating state into stable, transitional, and unstable states using the extension phase plane to implement the real-time division of the operating state. The vehicle’s yaw rate and side slip angle are tracked in real time by the lower controller using the linear quadratic optimal adjustment method (LQR). The additional front wheel angle and additional yaw moment are output at the same time that the weight matrix of the optimization objective function is modified depending on the correlation function value. The co-simulation platform was built by Simulink and Carsim, and the two-lane change condition and sinusoidal steering experiments were carried out respectively. The results demonstrate that the integrated control strategy based on extension LQR can successfully compensate for the active front wheel steering system’s shortcomings. The yaw rate, side slip angle, and power consumption of the executive system are reduced.