Method and apparatus for controlling electric power steering
The present invention relates to a method and apparatus for controlling electric power steering. In particular, the present invention provides a power steering control method that includes: a breakdown detection step of detecting whether a torque sensor has broken down; an information reception step of receiving steering angle information and vehicle speed information in the case in which the torque sensor has broken down; a compensation target value calculation step of calculating a self-aligning torque, and a damping force, an inertial force, and a frictional force of an electric power steering apparatus by using one or more of the steering angle information and the vehicle speed information; and a current control step of calculating a steering assist force based on the compensation target value and controlling the supply of a motor control current that corresponds to the steering assist force, and an apparatus for the same.
1. A method for controlling power steering, comprising:
a breakdown detection step of detecting whether a torque sensor has broken down;
an information reception step of receiving steering angle information and vehicle speed information in the case in which the torque sensor has broken down;
a compensation target value calculation step of calculating a self-aligning torque, a damping force, an inertial force, and a frictional force of an electric power steering apparatus by using one or more of the steering angle information and the vehicle speed information; and
a current control step of calculating a steering assist force based on the compensation target value and controlling the supply of a motor control current that corresponds to the steering assist force.
2. The method of claim 1 , wherein the steering angle information is received from a steering angle sensor or a motor position sensor.
3. The method of claim 1 , wherein the compensation target value calculation step comprises:
calculating lateral acceleration based on the steering angle information, the vehicle speed information, and preset vehicle characteristic information; and calculating the self-aligning torque based on the calculated lateral acceleration information.
4. The method of claim 3 , wherein the vehicle characteristic information comprises one or more of vehicle wheelbase information, under steer gradient constant information, information on the acceleration of gravity, and information on the gear ratio between a steering wheel and a tire.
5. The method of claim 3 , wherein the compensation target value calculation step further comprises:
identifying slip angle information that corresponds to the lateral acceleration information; and calculating the self-aligning torque that corresponds to the slip angle information.
6. The method of claim 5 , wherein the compensation target value calculation step further comprises:
calculating the self-aligning torque only when it is determined that the lateral acceleration information is within a preset linear interval.
7. The method of claim 3 , wherein the compensation target value calculation step further comprises:
comparing the calculated lateral acceleration information with a sensed value detected by a lateral acceleration sensor; and calculating the self-aligning torque based on the comparison result.
8. The method of claim 7 , wherein the compensation target value calculation step further comprises:
calculating the self-aligning torque based on the lateral acceleration information when the calculated lateral acceleration information is within a preset range based on the sensed value.
9. The method of claim 1 , wherein the compensation target value calculation step comprises:
calculating steering angular velocity information by using the steering angle information; and calculating the damping force that corresponds to the steering angular velocity information.
10. The method of claim 1 , wherein the compensation target value calculation step comprises:
calculating steering angular acceleration information by using the steering angle information; and calculating the inertial force that corresponds to the steering angular acceleration information.
11. The method of claim 1 , wherein the compensation target value calculation step comprises:
obtaining the direction of the frictional force based on steering angular velocity information calculated by using the steering angle information; and calculating the frictional force that corresponds to the vehicle speed information.
12. The method of claim 1 , wherein the motor control current is calculated by adding a restoration control current for the self-aligning torque, a damping control current for the damping force, an inertia control current for the inertial force, and a friction control current for the frictional force.
13. The method of claim 1 , wherein the current control step comprises:
determining whether a vehicle turns; and controlling the supply of the motor control current only when the vehicle turns.
14. An apparatus for controlling power steering, comprising:
a breakdown detection unit that detects whether a torque sensor has broken down;
an information reception unit that receives steering angle information and vehicle speed information in the case in which the torque sensor has broken down;
a compensation target value calculation unit that calculates a self-aligning torque, a damping force, an inertial force, and a frictional force of an electric power steering apparatus by using one or more of the steering angle information and the vehicle speed information; and
a current controller that calculates a steering assist force based on the compensation target value and controls the supply of a motor control current that corresponds to the steering assist force.