A motor control device for controlling operations of first and second motors provided with encoders and operable to drive first and second driven objects, respectively, comprising:
- first speed detecting means for detecting a travel speed of said first driven object based on an encoder output signal of said first motor, and issuing a current travel speed signal;
- first position detecting means for detecting a current position of said first driven object based on an encoder output signal of said first motor, and issuing a current travel position signal;
- first target speed signal output means for outputting a target speed signal corresponding to a target travel speed of said first driven object;
- first target position signal output means for outputting a target position signal corresponding to a target travel position of said first driven object;
- first speed difference detecting means for making a comparison between the target speed signal issued from said first target speed signal output means and the travel speed signal issued from said first speed detecting means, and outputting a speed difference signal corresponding to the difference detected by the comparison;
- first position difference detecting means for making a comparison between the target position signal issued from said first target position signal output means and the current position signal issued from said first position detecting means, and outputting a position difference signal corresponding to the position difference detected by the comparison;
- first motor drive means for driving said first motor so as to correct said speed difference and said position difference based on the speed difference signal sent from said first speed difference detecting means and the position difference signal sent from said first position difference detecting means;
- second speed detecting means for detecting a travel speed of said second driven object based on an encoder output signal of said second motor, and outputting a current travel speed signal;
- second position detecting means for detecting a current position of said second driven object based on an encoder output signal of said second motor, and outputting a current position signal;
- second target speed signal output means for outputting a target speed signal corresponding to a target travel speed of said second driven object corresponding to a predetermined drive speed ratio between said first and second driven objects based on the encoder output signal of said first motor;
- second target position signal output means for outputting a target position signal corresponding to a target travel position of said second driven object corresponding to a predetermined travel distance ratio between said first and second driven objects based on the current position signal of said first driven object sent from said first position detecting means;
- second speed difference detecting means for making a comparison between the target speed signal issued from said second target speed signal output means and the travel speed signal issued from said second speed detecting means, and outputting a speed difference signal corresponding to the speed difference detected by the comparison;
- second position difference detecting means for making a comparison between the target position signal issued from said second target position signal output means and said current position signal issued from said second position detecting means, and outputting a position difference signal corresponding to the position difference detected by the comparison;
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- second motor drive means for driving said second motor so as to correct the speed difference and the position difference based on the speed difference signal sent from said second speed difference detecting means and the position difference signal sent from said second position difference detecting means, wherein
- said first and second driven objects are driven to advance from a home position to a first position at an increasing speed, advance from the first position to a second position at a constant speed, and subsequently return to the home position;
- said first target speed signal output means is operable to output a constant-speed target speed signal corresponding to a constant target travel speed of said first driven object when the first driven object moved from the home position reaches the first position;
- said first target position signal output means is operable to output the target position signal corresponding to said second position when said first driven object moved from said home position reaches said first position;
- and
- said motor control device further includes means for controlling operations of said first and second motors such that said first and second driven objects advance from their home positions to the first positions at an increasing speed, and return from the second positions to the home positions.