| 摘要 |
PURPOSE:To compensate for the fluctuation of motor current due to inclination of rail by providing a library unit with a rail inclination sensor and feeding an accessor drive motor with a compensation current in accordance with a detected inclination. CONSTITUTION:Current position of an accessor can be known by the number of tachometer pulse outputted from a motor 35. A state estimating unit 33 estimates the moving speed of the accessor based on a time variation of tacho- pulse outputted from the motor and a current value outputted from an amplifier 32. When an inclination sensor detects an inclination, a compensation current generator 37 generates a compensation current which is then amplified and superposed on an output current from the amplifier 32 and then fed to the motor 35. At that time, polarity of the amplifier 37 is set to cancel the fluctuation of load torque due to the inclination of the rail. According to the constitution, fluctuation of motor drive current for attaining a target speed due to the inclination of the rail is compensated for by means of the compensation current generator 37 resulting in a stable motion control of the accessor. |
