To precisely control the rotation of a rotational body, when the rotational axis of the rotational body is not vertical and when the gravitational center of the rotational body is not on the rotational axis.
The rotation controller 10 for controlling the rotation of the rotational body such as a diffraction grating is provided with: a DC motor 12 for generating the power for the rotation; an encoder sensor 14 for detecting the rotational angle of the rotational body; a PID control part 184 for determining the torque generated by the DC motor 12 by a driving current, on the basis of the difference between the instruction angle and the detected rotational angle (outputted by a subtractor 182), in order to adjust the rotational angle of the rotational body to the instruction angle; and an inertial bias correction part 185 for determining the torque generated by the DC motor 12 by the driving current, on the basis of the error between the difference and the angle in which the rotational body is actually rotated by the DC motor 12 generating the torque determined by the PID control part 184.
NISHINA SHIGEKI
KAWAMURA YOSHIKO
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