Motor controller

A motor controller which controls a servo motor for driving a machine,

• the motor controller comprising:
• a speed command unit which issues a speed command for commanding a speed of the machine;
• a speed detection unit which detects a speed of the servo motor;
• and
• a speed control unit which produces a torque command based on the speed command issued by the speed command unit and a motor speed detected by the speed detection unit so as to control the speed of the servo motor,
• wherein the speed control unit includes a filter which approximates an inverse characteristic of a transmission characteristic from the servo motor to the machine,
• the filter has a transmission characteristic F(s) of formula below based on a frequency ω, a vibration damping coefficient ζ and a cutoff frequency ωadj which are adjustment parameters and
• the frequency ω is adjusted so as to be equal to or more than an antiresonant frequency ω0 of the machine but less than a resonant frequency ωp of the machine.
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