Abstract: Aiming at the problem of emergency steering of heavy commercial vehicles, a new method to realize emergency steering by using a new integrated electric-hydraulic steering system(IEHS) for commercial vehicle is proposed. Aiming at the key problems of smoothness and effectiveness of emergency steering switching control of IEHS system, an emergency steering control method of IEHS system based on hybrid theory is studied, to meet the new mandatory requirements of the latest emergency steering regulations on the steering system of heavy commercial vehicles. Among them, the upper layer performs the hybrid switching control of normal steering and emergency steering mode according to the switching logic, and the lower layer uses fuzzy PID control to accurately follow the target current. The simulation verification of switching control between normal steering and emergency steering is carried out under the environment of MATLAB / Simulink, and the test verification of emergency steering function is carried out on the hardware in the loop test bench. The simulation and test results show that the proposed emergency steering control method can better realize the emergency steering function when the hydraulic part of IEHS system fails, ensure the timeliness and smoothness of hybrid switching, and meet the requirements of emergency steering regulations.

Key words: integrated electric-hydraulic steering, emergency steering, mode switching, control strategy