Servomotor control device, servomotor control method, and computer readable recording medium

A servomotor control method for a servomotor control device, the method comprising the steps of:

• creating a velocity command value for driving a servomotor;
• detecting velocity of the servomotor;
• and
• creating a torque command value to the servomotor using a difference between the velocity command value thus created and a velocity detection value thus detected,
• wherein the servomotor is controlled according to the torque command value,
• wherein at least the detecting of the velocity of the servomotor and the creating of the torque command value are performed in a velocity control loop,
• wherein the creating of the torque command value is performed using proportional gain to which the difference is inputted, and an integral gain and an integrator to which the difference is inputted, and a calculation cycle for calculating a proportional term by the proportional gain is shorter than a calculation cycle for calculating an integral term by the integral gain and the integrator,
• wherein the integral gain is a value calculated by multiplying an initial value for the integral gain decided in advance for every motor model, by a ratio of total inertia of a machine relative to rotor inertia of the servomotor, and a value set smaller than the square of a velocity gain magnification according to delay time of the velocity control loop, and
• wherein the proportional gain is a value calculated by adding a value according to a difference in calculation cycle between the integral term and the proportional term, and the integral gain, to a value calculated by multiplying an initial value for the proportional gain decided in advance for every motor model, by a ratio of the total inertia of the machine relative to rotor inertia of the servomotor and the velocity gain magnification.

A non-transitory computer-readable recording medium storing a servomotor control program for enabling a computer, serving as a servomotor control device that controls a servomotor, to execute processing of:

• creating a velocity command value for driving the servomotor;
• detecting a velocity of the servomotor;
• and
• creating a torque command value for the servomotor using a difference between the velocity command value thus created and a velocity detection value thus detected,
• wherein at least the processing of detecting the velocity and the processing of creating the torque command value are executed in a velocity control loop,
• wherein the processing of creating the torque command value is performed using proportional gain to which the difference is inputted, and an integral gain and an integrator to which the difference is inputted, and a calculation cycle for calculating a proportional term by the proportional gain is shorter than a calculation cycle for calculating an integral term by the integral gain and the integrator,
• wherein the integral gain is a value calculated by multiplying an initial value for the integral gain decided in advance for every motor model, by a ratio of total inertia of a machine relative to rotor inertia of the servomotor, and a value set smaller than the square of a velocity gain magnification according to delay time of the velocity control loop, and
• wherein the proportional gain is a value calculated by adding a value according to a difference in calculation cycle between the integral term and the proportional term, and the integral gain, to a value calculated by multiplying an initial value for the proportional gain decided in advance for every motor model, by a ratio of the total inertia of the machine relative to rotor inertia of the servomotor and the velocity gain magnification.