Steering holding judging apparatus for vehicle and electric power steering apparatus equipped with the same

A steering holding judging apparatus for a vehicle, comprising:

• at least two steering angle sensors to detect a steering angle of a steering system of a vehicle;
• and
• a steering state judging section to calculate a hysteresis central value by using a hysteresis signal that sets a hysteresis width for steering signals from said two steering angle sensor, judge a steering state by using said hysteresis central value, and output a provisional steering information,
• wherein said hysteresis central value is calculated by a hysteresis filter process using said hysteresis signal,
• wherein said hysteresis width is set by being added or being subtracted a value 1 which is larger than a noise width of said steering angle signal and is smaller than a friction of a column shaft, to or from a steering angle 1 detected from a steering sensor which detects an input side steering angle of said column shaft, and being added or being subtracted a value 2 which is added a value which a driver does not feel to a value which is larger than a noise width of said steering angle, to or from a steering angle 2 detected from a steering sensor which detects an output side steering angle of said column shaft, and
• wherein a steering holding state is detected based on said provisional steering information.

A steering holding judging apparatus for a vehicle, comprising:

• a control unit to control a motor, which is coupled to a steering system of a vehicle, by means of a driving current;
• a steering angle detecting means to detect a column input-side angle and a column output-side angle of said steering system, and output a column input-side angle signal and a column output-side angle signal;
• a steering state judging section to output a steering information and a steering holding signal of said steering system based on said column input-side angle signal and said column output-side angle signal;
• and
• a current limiting section to limit said driving current based on said steering information and said steering holding signal,
• wherein said steering state judging section comprises:
• a hysteresis width setting section to calculate and set hysteresis widths “A” and “B” (<“A”) to said column input-side angle signal and said column output-side angle signal, respectively;
• a hysteresis central value calculating section to calculate respective hysteresis central values of said hysteresis widths “A” and “B”;
• a hysteresis filter judging section to turn-ON or turn-OFF a hysteresis trigger signal based on said hysteresis central value of said hysteresis width “A”;
• and
• a switching judging section to output said steering information and said steering holding signal based on said hysteresis central value of said hysteresis width “A” when said hysteresis signal is OFF, and said hysteresis central values of said hysteresis widths “A” and “B” when said hysteresis signal is ON.

An electric power steering apparatus that assist-controls a steering system by calculating a torque control output current command value based on at least steering torque, and driving a motor based on said torque control output current command value, comprising:

• an angle detecting means to output a column input-side angle signal and a column output-side angle signal of said steering system;
• a steering state judging section to judge a steering state based on said column input-side angle signal and said column output-side angle signal, and output a steering holding signal and steering information;
• and
• a current limiting section to limit said torque control output current command value based on said column input-side angle signal, said column output-side angle signal, said steering holding signal and said steering information,
• wherein said steering state judging section comprises:
• a hysteresis width setting section for said column input-side angle signal;
• a hysteresis width setting section for said column output-side angle signal;
• a calculating section for said column input-side angle signal to calculate a hysteresis central value to said hysteresis width;
• a calculating section for said column output-side angle signal to calculate a hysteresis central value to said hysteresis width;
• a judging section for said column input-side angle signal to judge a steering holding and a steer-forward or a steer-backward;
• and
• a judging section for said column output-side angle signal to judge a steering holding and a steer-forward or a steer-backward, and
• said current limiting section performs a current limiting of said torque control output current command value in a range of a current which a steering holding state is maintained.