Control unit for electric power steering device

A control unit for an electric power steering device provided with

• a first magnetostrictive film and a second magnetostrictive film with magnetic anisotropic properties opposite in direction to each other, each formed circumferentially on a surface of a steering shaft, and
• a first detection coil and a second detection coil provided around the first magnetostrictive film and the second magnetostrictive film, respectively, for detecting a twisting torque applied to the steering shaft based on an actual detection value of each of the first detection coil and the second detection coil to adjust an assist amount for the steering shaft,
• the control unit further comprising:
• a storage unit for storing
• an initial characteristic curve C1 formed from an initial detection value Z1 of the first detection coil when only the twisting torque T1 is applied to the steering shaft, and an initial characteristic curve C2 formed from an initial detection value Z2 of the second detection coil when only the twisting torque T1 is applied to the steering shaft;
• and
• a characteristic curve C3 being formed from the actual detection value P1 of first detection coil, and a characteristic curve C4 being formed from the actual detection value P2 of the second detection coil;
• and
• a bending load detector for detecting the bending load amount acting on the steering shaft based on
• a difference ΔS between the actual detection value P1 on the characteristic curve C3 and the initial detection value Z1 on the initial characteristic curve C1, and on
• a difference ΔS between the actual detection value P2 on the characteristic curve C3 and the initial detection value Z2 on the initial characteristic curve C2.