Patent ID: 8868297

Claim:
A power steering system, comprising: a steering mechanism constituted by a steering shaft, the steering shaft including an input axle connected to a steering wheel and an output axle connected to the input axle via a torsion bar, and a conversion mechanism that converts a rotation of the steering shaft to a steering operation of steerable wheels; a steering angle sensor constituted by magnetic reluctance elements and arranged to output sinusoidal wave signals and cosine wave signals which are rotation angle information of the steering shaft; a torque sensor constituted by resolvers and arranged to output other sinusoidal wave signals and cosine wave signals which are at least rotation angle information of the output axle to detect a torque generated on the steering shaft using a relative angle between the input axle and output axle; an electrically driven motor that provides a steering assistance force for the steering mechanism; a first control unit having a single core microcomputer in which a single processor core is mounted within a single processor package; a steering angle signal receipt section installed in the first control unit to receive output signals from the steering angle sensor; a torque signal receipt section installed in the first control unit to receive other output signals from the torque sensor; a first angle calculation process section installed in the first control unit to calculate rotation angles of the input axle and output axle on a basis of the sinusoidal wave signals and cosine wave signals received from the steering angle signal receipt section and torque signal receipt section; a second control unit having a multi-core microcomputer in which a plurality of processor cores are mounted within another single processor package; first information communication circuit and second information communication circuit interposed between the first control unit and the second control unit, the first information communication circuit transmitting an information within the first control unit to the second control unit and the second information communication circuit transmitting an information within the second control unit to the first control unit; a motor control section installed in the second control unit to drivingly control the electrically driven motor on a basis of the rotation angles of the input axle and output axle which are calculation results of the first control unit transmitted via the first information communication circuit; and an abnormality detection process section installed in the second control unit to detect an abnormality of the first angle calculation process section of the first control unit.