Control device and control method for electric power steering apparatus, and motor module

A control device for controlling a steering system including an input shaft and an output shaft, the control device comprising:

• a processor;
• and
• a storage device storing a program for controlling an operation of the processor,
• the processor being configured to, in accordance with the program,
• determine whether a vehicle is in a straight-ahead traveling state, based on a vehicle speed detected by a vehicle speed sensor, a steering wheel torque applied to a steering wheel, and a steering wheel angle as a rotation angle of the input shaft,
• store the steering wheel angle in the memory when determining that the vehicle is in the straight-ahead traveling state,
• store the steering wheel angle in the memory multiple times when determining that the vehicle is in the straight-ahead traveling state, and
• calculate a corrected steering angle amount from a weighted average of the steering wheel angles stored in the memory.