Electric power steering apparatus

An electric power steering apparatus having a steering system capable of flexibly setting a relationship between a steering angle of a steering wheel and a wheel angle of a tire, comprising:

• a first motor for controlling steering reaction force exerted on said steering wheel;
• a second motor for controlling said wheel angle of said tire;
• a steering angle detection section for detecting said steering angle of said steering wheel;
• an on-center region determination section for determining whether said steering wheel is in a position of an on-center region;
• a tire reaction force torque detection section for detecting tire reaction force torque transferred from said tire;
• and
• a control section for calculating a steering torque based on said tire reaction force torque detected by said tire reaction force torque detection section and a torque gain, for controlling said first motor to exert said steering reaction force corresponding to said calculated steering torque on said steering wheel, for calculating said wheel angle based on said steering angle detected by said steering angle detection section and an angle gain, and for controlling said second motor so that said wheel angle of said tire corresponds to said calculated wheel angle,
• wherein said control section sets said torque gain in case of determining that said steering wheel is in the position of said on-center region larger than said torque gain in case of determining that said steering wheel is not in the position of said on-center region, and sets said angle gain in case of determining that said steering wheel is in the position of said on-center region smaller than said angle gain in case of determining that said steering wheel is not in the position of said on-center region.

An electric power steering apparatus having a steering system capable of flexibly setting a relationship between a steering angle of a steering wheel and a wheel angle of a tire, comprising:

• a first motor for controlling steering reaction force exerted on said steering wheel;
• a second motor for controlling said wheel angle of said tire;
• a steering wheel angle detection section for detecting said steering angle of said steering wheel;
• an on-center region determination section for determining whether said steering wheel is in a position of an on-center region;
• a tire reaction force torque detection section for detecting tire reaction force torque transferred from said tire;
• and
• a control section for calculating steering torque based on said tire reaction force torque detected by said tire reaction force torque detection section and a torque gain, controlling said first motor to exert said steering reaction force corresponding to said calculated steering torque on said steering wheel, for calculating said wheel angle based on said steering angle detected by said steering angle detection section and an angle gain, and controlling said second motor so that said wheel angle of said tire corresponds to said calculated wheel angle,
• wherein said control section sets said torque gain in case of determining that said steering wheel is in the position of said on-center region smaller than said torque gain in case of determining that said steering wheel is not in the position of said on-center region, and sets said angle gain in case of determining that said steering wheel is in the position of said on-center region larger than said angle gain in case of determining that said steering wheel is not in the position of said on-center region.