Digital control of the positioning of mechanisms,especially of movable members of x-ray diffractometers

Abstract

Abstract 1,111,266. Digital control systems. W. HOPPE. 17 May, 1965 [15 May, 1964], No. 20863/65. Heading G4H. In a digital control system for controlling the movement of a part of an apparatus there is a motor for moving the part and coarse and fine digital control arrangements, the coarse control being incremental, operable in accordance with a predetermined number of steps of the motor, and the fine control comprising a digital encoder rotating with the motor to produce a position signal for comparison with a stored coded number representing the desired position of the part. The desired position represented by a decimal number is entered into a store #α, e.g. from a tape. The most significant digits of this number are compared with the contents of a counter 9 which receives a pulse for each pulse applied from oscillator 5 through gate 1 to the motor 6. When the numbers agree an output B from comparator 7 resets flip-flop FF2 to close gate 2 and prevent further pulses reaching the motor. It also initiates the fine control by enabling the digital encoder. This may be done by switching on the lamps L if the sensing is photo-electric, or by energizing a solenoid to bring sensing contacts into engagement with the coded scale if this is conductive. The output of the encoder is compared in diode gates 3 with the least significant digits of the number stored and if further adjustment of the motor is necessary a signal is passed via gate 2 to flip-flop FF2 to open gate 1 and allow another pulse to pass to the motor. This check is made after each pulse until agreement is reached. A number of motors may be controlled e.g. to move parts in three co-ordinates. All the motors are supplied from the same oscillator and a single counter is used. As each reaches its required coarse value it switches to the fine control.

Inventors

• 👤 Walter Hoppe

Bibliographic Details