Spindle positioning apparatus

Claim 1

A spindle positioning apparatus comprising: an absolute angle detector operatively coupled to a spindle motor, said absolute angle detector comprising a first resolver; a spindle drivable by the spindle motor; an absolute position detector operatively coupled to said spindle, said absolute position detector comprising a second resolver; and a position control processing system for deriving a positional error from detected signals from said absolute angle detector and a target position command signal whereby said spindle can be accurately and quickly positioned, said position control processing system further comprising, a first position error processor for deriving a positional error of said spindle from a spindle position command signal and the detected signal from said absolute position detector and for generating a position error signal indicative of the position of said spindle; and a second position error processor for deriving a deviation between said spindle motor and said spindle from the detected signal from said absolute angle detector and from a signal based on said position error signal from said first position error processor.

Claim 5

A method for controlling and positioning a spindle comprising the steps of: operating a spindle positioning system in one of three modes, the first mode being a speed control mode, the second mode being a positioning mode and the third mode being a position holding mode; selectively driving said spindle by a motor; generating a speed command signal; generating phase data signals indicative of a phase of the motor and a phase of the spindle; generating a positioning signal; generating a position command signal; feeding said speed command signal, phase data signals, positioning signal and position command signal to a control unit; using said speed command signal and a portion of said phase data signals in said control unit when operating in said first mode, said portion of said phase data signals being indicative of the phase of the motor; generating command signals from said control unit in response to at least said using said speed command signal and a portion of said phase data signals; supplying a driving current to said motor from a current control device in response to at least said command signals whereby said motor will be rotated at a constant speed when operating in said first mode; using said positioning signal, said position command signal and said phase data signals in said control unit when operating in said second mode, said using said positioning signal, said position command signal and said phase data signals further comprising the steps of, calculating a positional error based on a portion of said phase data signals and said position command signal and generating a positional error signal in response thereto, said position of said phase data signals being indicative of the phase of said spindle, calculating position correction data based at least on said positional error signal and a portion of said phase data signals and generating a position correction data signal in response thereto, said portion of said phase data signals being indicative of the phase of the motor, and converting said position correction data signal to a modified speed command data signal; sending said modified speed command data signal to said current control device when operating in said second mode; modifying the current supplied to the motor by said current control device in response to said modified speed command data signal for causing the motor to rotate said spindle to a position responsive to said positioning signal when operating in said second mode; and fixing an output associated with said positional error signal at a target value when operating in said third mode whereby external forces tending to rotate said spindle will be countered by reactive forces from said motor to thereby hold said spindle in position.

Claim 6

A method for controlling and positioning a spindle comprising the steps of: operating a spindle positioning system in one of three modes, the first mode being a speed control mode, the second mode being a positioning mode and the third mode being a position holding mode; selectively driving said spindle by a motor; generating a speed command signal; generating phase data signals indicative of a phase of the motor and a phase of the spindle; generating a positioning signal; generating a position command signal; feeding said speed command signal, phase data signals, positioning signal and position command signal to a control unit; using said speed command signal and a portion of said phase data signals in said control unit when operating in said first mode, said portion of said phase data signals being indicative of the phase of the motor; generating command signals from said control unit in response to at least said using said speed command signal and a portion of said phase data signals; supplying a driving current to said motor from a current control device in response to at least said command signals whereby said motor will be rotated at a constant speed when operating in said first mode; using said positioning signal, said position command signal and said phase data signals in said control unit when operating in said second mode, said using said positioning signal, said position command signal and said phase data signals further comprising the steps of, calculating a positional error based on a portion of said phase data signals and said position command signal and generating a positional error signal in response thereto, said position of said phase data signals being indicative of the phase of said spindle, calculating position correction data based at least on said positional error signal and a portion of said phase data signals and generating a position correction data signal in response thereto, said portion of said phase data signals being indicative of the phase of the motor, and converting said position correction data signal to a modified speed command data signal; sending said modified speed command data signal to said current control device when operating in said second mode; modifying the current supplied to the motor by said current control device in response to said modified speed command data signal for causing the motor to rotate said spindle to a position responsive to said positioning signal when operating in said second mode; and fixing an output associated with said positional error signal at a target value when operating in said third mode whereby external forces tending to rotate said spindle will be countered by reactive forces from said motor to thereby hold said spindle in position.