Motor controlling apparatus for suppressing vibrations

A motor control apparatus for controlling a servo motor, comprising:

• a position command generator configured to generate a position command of the motor;
• a compensation filter configured to compensate the position command generated by the position command generator;
• and,
• a servo control unit configured to control the movement of the motor based on a position command after compensation which is the compensated position command by the compensation filter,
• wherein the compensation filter includes a filter F(s) having an inertia Jr of a driven part, a stiffness coefficient K of an elastically deformable part and a damping coefficient C of the elastically deformable part as the elements of filter coefficients,
• wherein the filter F(s) included in the compensation filter is represented by F(s)=(JL×s2+C×s+K)/(C×s+K) wherein the position command after compensation is determined by adding a differential compensation amount for implementation of a filter, F(s)−1=(JL×s2)/(C×s+K), on the position command, to the position command,
• wherein the compensation filter includes:
• an acceleration command operator configured to calculate an acceleration command from the position command;
• a first compensation amount operator configured to multiply the acceleration command output from the acceleration command operator by a gain JL/K, determined by the inertia JL of the driven part and the stiffness constant K of an elastically deformable part;
• and,
• a second compensation amount operator configured to implement a first order low-pass filter with a time constant of C/K, determined by the damping constant C of the elastically deformable part and the stiffness constant K of the elastically deformable part, on a first compensation amount output from the first compensation amount operator,
• wherein the filter F(s) is realized by adding a second compensation amount output from the second compensation amount operator, to the position command,
• wherein the gain JL/K is determined by the inertia JL of the driven part and the stiffness constant K of the elastically deformable part,
• wherein the time constant C/K is determined by the damping constant C of the elastically deformable part and the stiffness constant K of the elastically deformable part, and
• wherein the gain JL/K and the time constant C/K are input to realize the filter F(s) after being determined by the following equations using the frequency ω and the vibration attenuation coefficient ξ
• JL/K=1/ω2
• C/K<=2ξ/ω.