Patent GB-1277022-A (GB)
Title: Program selecting control means for a driven member
Inventor: LODI EDGAR R
IPC: B25J9/16
Filed: 1968-08-22
Abstract: 1277022 Programmed control systems AMF Inc 22 Aug 1969 [22 Aug 1968] 40207/68 Heading G3N The Specification relates to a servo drive system, particularly to position an articulated arm sequentially to a plurality of selected positions. For example the arm may pick up, move, position then locate and lower a workpiece into a jig, then remove it and reject it on to a conveyer. The sequence is controlled by a counter 166 which selectively energizes relays e.g. 24, 26 thus rendering potentiometers e.g. 22 effective to transmit a control signal to a differential amplifier 70, also to a servo drive amplifier 272. Signal lamps e.g. 34 are energized by further contacts. The potentiometer signals represent the desired displacement of a servo drive to a selected position. Signals from an actual position potentiometer 33 are also fed to servocontrol circuit 272 also amplifier 70, a zero output from which causes the counter to stop. An output signal on terminal 6 of amplifier 70 is fed to a pair of comparators 88, 92 having feedback resistors 102, 104, and directional shunting diodes e.g. 94, 96. Comparator outputs are connected through transistors 112, 116 to AND gate 139 and thence to NAND gates 142, 144 and AND gate 146. The output signals of NAND gates 142, 144 are fed to NAND gate 160 and a transistor 151 which shunts a capacitor 169 of a relaxation oscillator 164 which normally develops single pulses, the oscillacor output being amplified in transistor 179 and passed through a silicon switch counter 166 which also receives signals from a one shot multivibrator 210 on terminals 172 and 174. Each thyristor 181 is anode triggered and drives a transistor 194 to conduct and hence earth a terminal 250 and also energize a lamp 198. Stages of the counter may be selectively shunted out and the counter may be arranged to step at a higher rate during this period, The counter may be stopped manually by a switch 262, and another switch 248 may be closed to provide a dwell condition. Any potentiometer e.g. 22 may be reactivated a number of times during any sequence by coupling the corresponding relay to a appropriate terminals 250, also by coupling terminals 250 to terminal 266 and closing a switch 268 the pulse generator 164 will free run and automatically step counter 166, Counter may be stepped manually by a switch 262. The arm may have a clamp which is operated and released through a circuit 307 connected to AND gate 146. Similar circuits Fig.1C (not shown) are provided if more than one axis of movement is required. For each axis, relays 26 etc. are coupled singly and sequentially to terminals 250 of counter 166 which activate the relevant potentiometer, hence the arm is driven to each required position by comparison with a positional error signal from potentiometer 33, and when the error is within the determined limits the counter 166 is advanced. If at any stage e.g. 201 the clamp is required to be operated, a terminal e.g. 252 of circuit 307 is coupled to terminal 250 of stage 201, hence self-latching relay 251 will be energized when stage 201 is activated. This will prevent further stepping of the counter until it is released after a delay determined by a R.C. network 256, 258 in gate 142 which allows sufficient time for the clamp to perform its particular function. A reset switch 270 couples terminal 240 to ground and triggers bi-stable circuit 210 hence grounds terminals 174 of all stages of the counter 166 which resets it,