Steering control device

1. A steering control device comprising:

a controller that controls driving of a motor using a steering torque, the steering torque being input by a driver to steer a steering mechanism such that a steerable wheel of a vehicle steers, the motor generating an assist force applied to the steering mechanism, the controller comprising:

a basic assist component calculator that calculates a basic assist component based on the steering torque, the basic assist component being a basic component of the assist force that should be generated by the motor,

a pinion angle calculator that calculates a pinion angle of a pinion shaft that drives a rack of the steering mechanism,

an angle command value calculator that calculates an angle command value based on an additional value of the steering torque, the basic assist component, and the calculated pinion angle, the angle command value corresponding to a target value of the pinion angle of the pinion shaft that is convertible into a steerable angle of the steerable wheel,

an angle feedback controller that calculates an assist command value based on the angle command value by executing angle feedback control such that the pinion angle follows the angle command value, the assist command value corresponding to a target value of the assist force,

a control signal generator that generates a motor control signal using the assist command value, and

wherein the basic assist component calculator comprises:

a torque command value calculator that directly receives the steering torque and a speed of the vehicle, and calculates a torque command value based on the steering torque and the speed, the torque command value corresponding to a target value of the steering torque that should be input by the driver, and

a torque feedback controller that calculates the basic assist component based on the torque command value by executing torque feedback control such that the steering torque follows the torque command value, and

wherein the steering control device further comprises a drive circuit that controls the motor based on the motor control signal generated by the control signal generator.

2. The steering control device according to claim 1 , wherein the angle command value calculator calculates the angle command value using a model expression represented so as to relate an input torque on the pinion shaft to the pinion angle.

3. The steering control device according to claim 2 , wherein the angle command value calculator includes a compensation component calculator that calculates a compensation component that compensates the assist command value so as to be optimized to a state of the vehicle or a state of the steering mechanism for the vehicle.

4. The steering control device according to claim 1 , further comprising a friction compensation controller that calculates a friction component for the torque input to the steering mechanism, based on a vehicle speed value and the pinion angle.

5. A steering control device comprising:

a processor configured to control driving of a motor using a steering torque, the steering torque being input by a driver to steer a steering mechanism such that a steerable wheel of a vehicle steers, the motor generating an assist force applied to the steering mechanism, the processor being further configured to:

calculate a basic assist component based on the steering torque, the basic assist component being a basic component of the assist force that should be generated by the motor,

calculate a pinion angle of a pinion shaft that drives a rack of the steering mechanism,

calculate an angle command value based on an additional value of the steering torque, the basic assist component, and the calculated pinion angle, the angle command value corresponding to a target value of the pinion angle of the pinion shaft that is convertible into a steerable angle of the steerable wheel,

calculate an assist command value based on the angle command value by executing angle feedback control such that the pinion angle follows the angle command value, the assist command value corresponding to a target value of the assist force,

generate a motor control signal using the assist command value, and

wherein the processor:

further comprises a torque command value circuit that directly receives the steering torque and a speed of the vehicle, and is configured to calculate a torque command value based on the steering torque and the speed, the torque command value corresponding to a target value of the steering torque that should be input by the driver, and

further comprises a torque feedback control circuit configured to calculate the basic assist component based on the torque command value by executing torque feedback control such that the steering torque follows the torque command value, and

wherein the steering control device further comprises a drive circuit that controls the motor based on the motor control signal.

6. The steering control device according to claim 1 , wherein the basic assist component calculator further comprises an adder that:

adds the steering torque and the basic assist component to generate an added value, and

inputs the added value to the torque command value calculator.

7. The steering control device according to claim 5 , wherein the processor further comprises an adder that:

adds the steering torque and the basic assist component to generate an added value, and

inputs the added value to the torque command value circuit.

8. A steering control device comprising:

a controller that controls driving of a motor using a steering torque, the steering torque being input by a driver to steer a steering mechanism such that a steerable wheel of a vehicle steers, the motor generating an assist force applied to the steering mechanism, the controller comprising:

a basic assist component calculator that calculates a basic assist component based on the steering torque, the basic assist component being a basic component of the assist force that should be generated by the motor,

a pinion angle calculator that calculates a pinion angle of a pinion shaft that drives a rack of the steering mechanism,

an angle command value calculator that calculates an angle command value based on an additional value of the steering torque, the basic assist component, and the calculated pinion angle, the angle command value corresponding to a target value of the pinion angle of the pinion shaft that is convertible into a steerable angle of the steerable wheel, the angle command value calculator calculating the angle command value using a model expression represented so as to relate an input torque on the pinion shaft to the pinion angle,

an angle feedback controller that calculates an assist command value based on the angle command value by executing angle feedback control such that the pinion angle follows the angle command value, the assist command value corresponding to a target value of the assist force,

a control signal generator that generates a motor control signal using the assist command value, and

a friction compensation controller that calculates a friction component for the torque input to the steering mechanism, based on a vehicle speed value and the pinion angle,

wherein the basic assist component calculator comprises:

a torque command value calculator that directly receives the steering torque and the speed value of the vehicle, and calculates a torque command value based on the steering torque and the speed value, the torque command value corresponding to a target value of the steering torque that should be input by the driver, and

a torque feedback controller that calculates the basic assist component based on the torque command value by executing torque feedback control such that the steering torque follows the torque command value, and

wherein the steering control device further comprises a drive circuit that controls the motor based on the motor control signal generated by the control signal generator.