| 摘要 |
<p>PROBLEM TO BE SOLVED: To escape from a steering difficult state by flowing an electric current as much as possible to a motor at the time when stationary steering is at low speed by changing a feedback system over to an open loop system at the time when a failure detection circuit detects a failure of an electric current detection circuit. SOLUTION: Judgement of a failure of a motor driving circuit 37 is carried out by a value of motor terminal voltage Vm at the time when all of an FET constituting an H bridge in the motor driving circuit 37 is put off. When the motor driving circuit 37 is normal, if all the FET is put off, the motor terminal voltage Vm becomes 0, and when it is abnormal, it does not become 0. Thereafter, when a motor electric current detection circuit 38 is judged as it fails by a failure detection circuit 310, a change-over signal SS is output, a contact point of a change-over circuit 320 is changed from a contact point (a) over to a contact point (b), a feedback system of electric current control is changed over to an open loop of a motor model 330, and a steering auxiliary command value from a steering auxiliary command value computing element 32 is input to the motor model 330.</p> |
