Motor control apparatus equipped with dead-zone processing unit

A control apparatus for a motor, which drives and controls a driven body in accordance with a predefined action pattern by repeating a positions command of a specific pattern, comprising:

• a position detection unit which detects position of said driven body;
• a positional error acquiring unit which acquires for each sampling cycle a positional error representing a deviation between said position command given to said motor and said position of said driven body detected by said position detection unit;
• a dead-zone processing unit which replaces said positional error that is located within the dead-zone range with zero and outputs the zero, when (i) said positional error acquired by said positional error acquiring unit lies within a predetermined dead-zone range and when (ii) a speed command to said motor has remained equal to or less than a prescribed value for a predetermined period of time, or the speed detected on said driven body has remained equal to or less than a prescribed value for a predetermined period of time;
• and
• a repetitive control unit which calculates an amount of correction such that said positional error output from said dead-zone processing unit is reduced to zero, and wherein
• said motor is controlled based on said positional error acquired by said positional error acquiring unit and said amount of correction calculated by said repetitive control unit, and
• wherein said repetitive control unit includes:
• a low-pass filtering unit which cuts off high-frequency components,
• a memory unit which follows said low-pass filtering unit and which holds said amount of correction for at least a period equal to one sampling cycle, and
• an adder which sums together a value obtained by multiplying an output of the memory unit by a gain smaller than 1 and said positional error output from said dead-zone processing unit, and wherein
• said sum generated by said adder is fed to the low-pass filtering unit.