Steering control apparatus

1. A steering control apparatus comprising:

a torque sensor that detects a driver's steering force as a steering torque;

a motor that provides torque to a steering system;

a motor drive circuit that drives said motor;

a steering control section that receives said steering torque from said torque sensor and calculates at least a target current for said motor based on said steering torque;

a motor control section that receives said target current from said steering control section and provides an instruction to said motor drive circuit based on said target current;

a steering control verification section that receives said steering torque from said torque sensor and receives said target current from said steering control section and verifies an operation of said steering control section based on said steering torque and said target current; and

a motor control verification section that receives a state quantity from said motor drive circuit and verifies an operation of said motor control section based on said state quantity.

2. The steering control apparatus as set forth in claim 1 , further comprising:

a first and a second control section each including at least one of said steering control section, said motor control section, said steering control verification section, and said motor control verification section;

wherein said torque sensor and said motor drive circuit have their output terminals connected to said first and second control sections, respectively.

3. The steering control apparatus as set forth in claim 1 , further comprising:

a first and a second control section each including at least one of said steering control section, said motor control section, said steering control verification section, and said motor control verification section;

wherein the steering torque detected by said torque sensor and said state quantity input to said motor control section or said motor control verification section are input to said first and second control sections, respectively.

4. The steering control apparatus as set forth in claim 2 , wherein

said first control section includes said steering control section and said motor control section; and

said second control section includes said steering control verification section and said motor control verification section.

5. The steering control apparatus as set forth in claim 2 , wherein

said first control section includes said steering control section and said motor control verification section; and

said second control section includes said motor control section and said steering control verification section.

6. The steering control apparatus as set forth in claim 1 , wherein

said steering control verification section sets a reference value that verifies said target current based on said steering torque, and determines that the steering control section is abnormal, when said target current exceeds said reference value.

7. The steering control apparatus as set forth in claim 4 , wherein

said steering control verification section sets a plurality of reference values for comparison verification of said target current based on said steering torque; and

said second control section selects one of said plurality of reference values in accordance with an instruction from said first control section, determines that said steering control section is abnormal, when said target current exceeds the reference value thus selected, and restricts a period of time in which at least one of said plurality of reference values is in a selected state.

8. The steering control apparatus as set forth in claim 5 , wherein

said steering control verification section sets a plurality of reference values for comparison verification of said target current based on said steering torque;

said second control section selects one of said plurality of reference values in accordance with an instruction from said first control section, determines that said steering control section is abnormal, when said target current exceeds the reference value thus selected, and restricts a period of time in which at least one of said plurality of reference values is in a selected state.

9. The steering control apparatus as set forth in claim 4 , wherein

said steering control verification section sets a plurality of reference values for comparison verification of said target current based on said steering torque;

said second control section selects one of said plurality of reference values in accordance with an instruction from said first control section, and determines that said steering control section is abnormal, when said target current exceeds the reference value thus selected; and

said first control section provides said reference value selection instruction to said second control section in accordance with a predetermined periodic signal.

10. The steering control apparatus as set forth in claim 5 , wherein

said steering control verification section sets a plurality of reference values for comparison verification of said target current based on said steering torque;

said second control section selects one of said plurality of reference values in accordance with an instruction from said first control section, and determines that said steering control section is abnormal, when said target current exceeds the reference value thus selected; and

said first control section provides said reference value selection instruction to said second control section in accordance with a predetermined periodic signal.

11. The steering control apparatus as set forth in claim 1 , wherein

said motor control verification section verifies an operation of said motor control section based on a voltage impressed on said motor by said motor drive circuit.

12. The steering control apparatus as set forth in claim 11 , wherein

when a sum of the values of voltages impressed by said motor drive circuit on respective terminals of said motor is outside a predetermined range, said motor control verification section determines that said motor control section is abnormal.

13. The steering control apparatus as set forth in claim 11 , wherein

said motor control section drives said motor in a PWM fashion; and

when the period of a PWM signal impressed by said motor drive circuit on respective terminals of said motor is outside a predetermined range, said motor control verification section determines that said motor control section is abnormal.

14. The steering control apparatus as set forth in claim 1 , wherein

said motor control verification section verifies an operation of said motor control section based on a current supplied to said motor.

15. The steering control apparatus as set forth in claim 14 , wherein

said motor comprises a three-phase motor; and

when a sum of the values of currents supplied from said motor drive circuit to respective phases of said motor is outside a predetermined range, said motor control verification section determines that said motor control section is abnormal.

16. The steering control apparatus as set forth in claim 14 , wherein

when a difference between said target current and a current supplied to said motor is outside a predetermined range, said motor control verification section determines that said motor control section is abnormal.

17. The steering control apparatus as set forth in claim 1 , wherein

said motor control verification section verifies an operation of said motor control section based on a rotor rotation angle of said motor.

18. The steering control apparatus as set forth in claim 1 , wherein

said motor control verification section verifies an operation of said motor control section based on a rotor angular velocity of said motor.

19. The steering control apparatus as set forth in claim 1 , wherein

said steering control verification section interrupts the current supplied to said motor when it is determined that said steering control section is abnormal.

20. The steering control apparatus as set forth in claim 1 , wherein

said motor control verification section interrupts a current supplied to said motor when it is determined that said motor control section is abnormal.

21. A steering control apparatus comprising:

a torque sensor that detects a driver's steering force as a steering torque;

a motor that provides torque to a steering system;

a motor drive circuit that drives said motor;

a steering control section that receives said steering torque from said torque sensor and calculates at least a target current for said motor based on said steering torque;

a motor control section that receives said target current from said steering control section and provides an instruction to said motor drive circuit based on said target current; and

a steering control verification section that receives said steering torque from said torque sensor and receives said target current from said steering control section and verifies an operation of said steering control section based on said steering torque and said target current.

22. The steering control apparatus as set forth in claim 21 , wherein

said steering control verification section sets a reference value that verifies said target current based on said steering torque, and determines that the steering control section is abnormal, when said target current exceeds said reference value.