Patent ID: 7533757

Claim:
A method of controlling a steering system, the steering system comprising an operating element operated by a driver; a steering input detecting unit which detects a steering input that is inputted to the operating element; a steering actuator which actuates steered road-wheels to rotate through a rotating angle, the steered road-wheels configured to be mechanically disconnected from the operating element; a reaction force actuator which imparts a reaction force to the operating element; a control unit which drives the steering actuator in accordance with the steering input detected by the steering input detecting unit; and a temperature detecting unit which detects a temperature of the steering actuator and the reaction force actuator, wherein the control of the steering system comprises the following method steps: determination of a representative temperature based on the detected temperatures, determination of a ratio of the rotating angle to the steering input, and determination of a reaction force to be imparted to the operating element, and wherein: when the representative temperature is equal to or lower than a primary predetermined temperature, normal operating conditions are implemented, in which the ratio of the rotating angle to the steering input is set to a first ratio value, and the reaction force is set to a first force value; when the representative temperature is higher than the primary predetermined temperature and lower than a second predetermined temperature, the second predetermined temperature being higher than the primary predetermined temperature, a first heat mitigation step is implemented, in which the ratio of the rotating angle to the steering input remains set at the first ratio value, and the reaction force is set at a second force value greater than the first force value; and when the representative temperature is higher than the second predetermined temperature and lower than a third predetermined temperature, the third predetermined temperature being higher than the second predetermined temperature, a second heat mitigation step is implemented, in which the ratio of the rotating angle to the steering input is set at a value less than the first ratio value, and the reaction force is set at a third force value greater than the second force value.