Patent GB-1215526-A (GB)
Title: Improvements in or relating to machine tool control apparatus
IPC: B23Q35/123
Filed: 1968-03-21
Abstract: 1,215,526. Programmed electric control. HONEYWELL Inc. March 21, 1968 [March 30, 1967], No.13790/68. Heading G3N. In a profiling machine having a pattern contacting tracing head movable in co-ordinate axes wherein a displacement vector signal is generated of magnitude and phase angle dependent on the position and direction of the head, and a command vector signal is generated of a magnitude dependent on the desired trace rate and a phase angle displaced 90 degrees from that of the displacement signal, the apparatus comprised first means to produce first and second signals the first signal being representative of the magnitude of a tool trace rate vector and the square of the sine of the phase angle of the trace rate command vector, the second signal being indicative of the product of the magnitude of the tool rate vector and the square of the cosine of the phase angle of the control rate vector, trace rate means to provide a signal indicative of the desired trace rate, and comparison means connected to said first means and to said trace rate means to compare the magnitude of the trace rate signal with the magnitude of the sum of first and second control signals, and means controlled by said comparison means to modify said trace rate command vector signal. The amplified control signal from a tracing head 15 is passed directly after amplification to a summation point 35 and also through a 180 degrees phase shift circuit 37 to the same point. The control signal is also passed through a 90 degrees shift circuit 39 to a potentiometer 40 the wiper 41 of which is connected to point 35 and the centre point to a reference potential 43. The control signal passes additionally through a phase detector 62 providing a reversible polarity D.C. output controlling a motor 75 mechanically coupled to a resolver 70 fed from a two phase reference source 71, the output of the resolver being fed into phase detector 62. An output of source 71 is also fed to the tracing head 15.  The output from point 35 is fed into X and Y axis demodulators 50, 51, each having a D.C. output which is fed into modulators 52, 53 the A.C. outputs from which control X, Y axis drive motors 17, 19 to which are coupled D.C. tachometers 18, 20. Each tachometer is connected to diammetrically opposite points of 360 degrees potentiometers 82, 83 the quadrature points of which are connected to reference potentials 86-89 and the wipers of which are driven by motor 75 and are electrically connected to a summation point 69 the output of which is fed to a reversible motor 104 positioning the wiper 41. The potentiometers 82, 83 are wound non-linearly such that the resistance between the points of reference potential approximates to a cosine function, these points being the maximum gradient points. The voltage on lines 100, 101 is summed at a summation point 69 to give the sum of V m  sine<SP>2</SP> # and V m  cosine<SP>2</SP> # where V m  is the magnitude of the trace rate vector and # is the angle which this vector makes with the X axis. The trace direction may be reversed by reversing the sign of phase shift circuit 39. The summation point 69 has a further input from a manually set potentiometer 66 which provides a signal representative of the desired rate.