Patent GB-753909-A (GB)
Title: Improved means for recording one or more motions in a machine and for subsequently causing the machine to repeat such recorded motions
Inventor: WILLOUGHBY ANTHONY HAYDN
IPC: G05B19/42
Filed: 1954-04-22
Abstract: 753,909. Electric control systems. DENHAM LABORATORIES, Ltd. April 22, 1954, No. 11665/54. Class 40(1) [Also in Group XX] The operation of a machine subjected to a plurality of control orders is recorded as separate phase modulated signals each having an individual frequency, together with air unmodulated reference signal, and the operation may be repeated by playing back the record and separating the several signals by band-pass filters to reproduce the phase modulated signals to effect control of appropriate servo-mechanisms. As shown for controlling the tracking, tilting and panning motions of a cinematograph camera, a master oscillator O (Fig. 1) produces a frequency of 6000 c.p.s. which is broken down in frequency dividers FD1-4 to frequencies of 3000. 2000, 1200 and 867 c.p.s. The first or reference frequency is fed directly to a mixer M. The others are fed to phase splitters SP1-3 respectively to energize the two or three phase stator windings of magslips MS1-3 whose rotors are mechanically connected to the manual control mechanisms H1-3 of the several camera shafts L1-3 whose displacements are to be recorded for repetition. The windings of the displaced rotors produce phase modulated data signals which are supplied to the mixer M, whose complex output, comprising the reference signal and three deflection signals, is recorded in known manner at R on a film magnetic tape or wire, or wax disc. The phase modulated data signals from MS1-3 are also fed through further phase splitters SP4-6 to energize further magslips MS4-6 whose rotor signals are compared in discriminators D1-3 with the unmodulated signals from the frequency dividers FD2-4 to produce error signals which, after amplification at PA1-3, drive servo motors M1-3 to control the appropriate camera shafts L1-3. To repeat the camera motion the recorded signal is applied to a playback machine P (Fig. 2) and the component frequencies are separated by bandpass filters BP1-4. The reference signal from BP1 synchronizes an oscillator O, which in turn synchronizes frequency dividers FD2-4 to produce the unmodulated reference signals. The control signals from BP2-4 are fed through phase splitters SP4-6 to energize magslips MS4-6, whose rotor signals are compared in discriminators D1-3 with the unmodulated reference signals to produce error signals which are amplified at PAI-3 to drive servo motors M1-3 controlling the appropriate camera shafts L1-3. Clutches C1-3 are located between the motors M1-3 and shafts L1-3 to facilitate zero adjustment of each phase shift circuit. The apparatus may be provided with multiple recording and reproducing heads so that the phase modulated signals may be dealt with individually instead of as a complex single wave. The invention is applicable to the control of automatic machine tools, and the recording and reproducing parts may be combined so that the common servo mechanisms can be switched from one circuit to the other. Specification 687,349 is referred to.