Servo control apparatus for driving plurality of motors

A servo control apparatus that performs control for driving one driven object by way of a master-axis motor on a master axis and a slave-axis motor on a slave axis, the apparatus comprising:

• a subtractor that calculates a difference between an integral value of a speed deviation of the master axis and an integral value of a speed deviation of the slave axis;
• a low pass filter that performs filtering of the difference;
• an adder that adds a result of the filtering to the integral value of the speed deviation of the slave axis to produce an addition result;
• and
• a CPU that estimates a torsional rigidity value of the driven object, based on a torsion angle of the driven object calculated based on a value of difference between a position feedback amount of the master axis and a position feedback amount of the slave axis, and each value of the first current command for rigidity estimation of the master axis and the second current command for rigidity estimation of the slave axis, wherein
• a current command for driving the master-axis motor is calculated for the master axis by using the integral value of the speed deviation of the master axis;
• a current command for driving the slave-axis motor is calculated for the slave axis by using the addition result of the adder;
• and
• a cutoff frequency of the low-pass filter is adjusted based on an estimated result of the CPU.