| 摘要 |
1,226,676. Programmed control of machines. GENERAL ELECTRIC CO. July 17, 1968 (Aug. 10, 1967], No.34137/68. Heading G3N. A numerical control system comprises a command signal generator, responsive to controlling input signals, for generating a command signal for a servo-control loop positioning a device, an absolute position register, for registering the desired position of the device, and a position tracking device for adjusting the position register and the command signal generator when the servoloop is interrupted. As shown, command signals are applied to a terminal 28 and fed to an absolute position register 12, indicating desired machine position, and a phase counter 10, providing a phase-controlled output waveform to an input of a discriminator 18 forming the comparison element of a control loop 35. The other input of the discriminator is supplied from a wave shaper 16 with a squarewave having a phase dependent upon the position of a machine 22 as sensed by a feedback transducer 24 comprising a resolver supplied with a sinusoidal waveform from a source 26. The discriminator detects the phase difference between the inputs and through a servo 20 moves the machine 22 towards the commanded position. The phase relationship between the inputs to the discriminator is also sensed by an update whenever the control loop 35 is interrupted. The output signal on lead 36 updates the absolute position register 12 whereby it always provides a correct numerical indication of the machine position. The machine control loop is interrupted by a switch not shown, to permit manual positioning which, it is stated, can be recorded to provide a programme for future automatic operation. |
