Electronically controlled steering method and steering system for vehicle

A steering system of a vehicle, the steering system comprising:

• an electronically controlled steering system including a hydraulic control system, steering knuckles disposed at respective steering vehicle wheels, and hydraulic wheel cylinders connected with the respective steering knuckles through piston rods;
• and
• a first control circuit configured to:
• receive steering parameters, including steering input torque, a steering input angle, vehicle speed, lateral acceleration of the vehicle and actual piston positions of pistons of the respective hydraulic wheel cylinders;
• determine a target steering radius for the vehicle and target piston positions of the pistons of the respective hydraulic wheel cylinders based on the steering parameters;
• control, based on the determined target piston positions, the hydraulic control system to change hydraulic pressures in the respective hydraulic wheel cylinders to change positions of the pistons thereof, so as to drive, through the piston rods, the steering knuckles connected therewith to deflect the corresponding steering vehicle wheels for steering;
• determine other target piston positions of the pistons of the respective hydraulic wheel cylinders corresponding to the steering vehicle wheels without steering failure of the respective steering vehicle wheels based on the steering parameters, when a steering failure occurs in one or more steering vehicle wheels of the respective steering vehicle wheels;
• and
• control, based on the determined other target piston positions, the hydraulic control system to change the hydraulic pressures of the respective hydraulic wheel cylinders corresponding to the steering vehicle wheels without steering failure to change the positions of the pistons thereof, so as to drive, through the piston rods, the steering knuckles connected therewith to deflect the corresponding steering vehicle wheels for steering.

An electronically controlled steering method for a vehicle including an electronically controlled steering system, the electronically controlled steering system including a hydraulic control system, steering knuckles disposed at respective steering vehicle wheels, and hydraulic wheel cylinders connected with respective steering knuckles through piston rods, the method comprising:

• receiving steering parameters, including steering input torque, a steering input angle, vehicle speed, lateral acceleration of the vehicle and actual piston positions of pistons of the respective hydraulic wheel cylinders;
• determining a target steering radius for the vehicle and target piston positions of the pistons of the respective hydraulic wheel cylinders based on the steering parameters;
• and
• controlling, based on the determined target piston positions, the hydraulic control system to change hydraulic pressures in the respective hydraulic wheel cylinders to change positions of the pistons thereof, so as to drive, through the piston rods, the steering knuckles connected therewith to deflect the corresponding steering vehicle wheels for steering;
• wherein determining the target steering radius and the target piston positions of the pistons of the respective hydraulic wheel cylinders comprises:
• determining an actual steering radius for the vehicle based on the vehicle speed and the lateral acceleration of the vehicle;
• and
• determining the target steering radius and the target piston positions of the pistons of the respective hydraulic wheel cylinders based on the actual steering radius, the steering input torque, the steering input angle, the vehicle speed, and the actual piston positions of the pistons of the respective hydraulic wheel cylinders;
• wherein the target steering radius and the target piston positions are used as feedback to determine the target steering radius and the target piston positions at next timing through closed-loop control;
• and
• wherein determining the target steering radius and the target piston positions at the next timing comprises:
• determining the actual steering radius at the next timing based on received vehicle speed and lateral acceleration of the vehicle at the next timing;
• determining a steering radius difference between the target steering radius and the actual steering radius at the next timing;
• determining piston position differences between the target piston positions and the received actual piston positions at the next timing;
• and
• determining the target steering radius and the target piston positions at the next timing by using received steering input torque, steering input angle, and vehicle speed at the next timing, the steering radius difference and the piston position differences, as inputs to a look-up table for determining target steering radius and target piston position.