System for controlling motors for synchronous operation

A system for controlling motors including a reference motor, such that the motors rotate at command speeds in synchronism and have respective rotational positions, said system comprising:

• numerical control means, operatively connected to receive commanded speeds of rotation, for generating as positional commands synchronized distributed pulse trains having frequencies corresponding to the commanded speeds of rotation for respective ones of the motors;
• positional control feedback circuits, operatively connected to respective ones of said motors and to receive respective ones of said positional command pulse trains, for producing speed command outputs in accordance with respective ones of said positional command pulse trains and said respective rotational positions;
• speed control feedback circuits, operatively connected between respective ones of said positional control feedback circuits and respective ones of said motors, for controlling the speed of the motors based on said speed command outputs and said speeds of rotation of the motors;
• detector means, operatively connected to said respective ones of the motors, for generating feedback pulses corresponding to the rotational positions of the respective motors each time the respective motors rotate through a predetermined angular interval and for applying these signals to said position control feedback circuits as said respective rotational positions;
• simulator circuit means, operatively connected to receive respective ones of said positional command pulse trains, for simulating the characteristics of respective positional and speed control feedback in combination with corresponding ones of said motors, and for generating pulses responsive to said simulations;
• and
• correction circuit means, operatively connected to said corresponding ones of said motors, to said positional and said speed control feedback circuits and to said simulator circuit means, for correcting the rotational positions of the motors in response to differences between the feedback pulses and the pulses generated by said simulator circuit means.