GB1435355A - Servo control - Google Patents

Abstract

1435355 Automatic control XENEX CORP 11 April 1973 17296/73 Heading G3N The value of a first quantity as a function of a second quantity is determined by command signals to effect servo-control of the first quantity; the signals being first and/or higher order digital difference of the first quantity in respect of the function for equal increments of the second quantity. As shown, a power servo 20 controls the X-axis movements of a machine-tool in response to input data on a tape read by a reader 10 and fed to an interpolator 12, which may be a general purpose digital computer. The X-axis movements are determined with respect to a spindle 22 driven by a motor 16 and coupled to a reference generator 14 providing a velocity signal VR, an incremental movement pulse #R and a direction signal DR. The interpolator provides, in response to signals DR, # R, command signals S 1 , S 2 , as parallel binary words, representative respectively of first order (velocity) and second order (acceleration) values of the function of X with respect to spindle rotation. The signals S 1 , S 2 are fed to a processing unit 18 and are gated by the signal # R, the signal Si being fed into a velocity channel 62 and a position error channel 60 and the signal S 2 fed into an acceleration channel 64. In channel 62 signal Si, through gate 80, updates a register 84 the contents of which, through a D/A converter 86, is weighted by the signal VR in a multiplier 86 to form the X-axis velocity signal VX. In channel 60 the signal Si, through gate 66, is summated in an adder 72 with the X-axis pulses #P from a transducer, (not shown), coupled to the X-axis servo-drive, and stored in a register 74 the contents of which is the position error; this error through a D/A converter 76 provides the signal EX. The channel 64 is similar to channel 62 but the signal VR is squared in a multiplier 106 to provide record-order weighting, through multiplier 102 to an X-axis acceleration signal AX. The X-axis servo 20 comprises an amplifier, summating the signals VX, EX, AX, which feeds a power amplifier, with rate feedback, energizing a servomotor. In an alternative embodiment the interpolator provides an acceleration signal only. It is stated that servo can be controlled solely by a velocity signal.