Patent GB-1043801-A (GB)
Title: Automatic positioning apparatus
IPC: G05B19/425
Filed: 1964-01-01
Abstract: 1,043,801. Programmed control. AMERICAN MACHINE & FOUNDRY CO. Jan. 1, 1964 [Jan. 7, 1963], No. 64/64. Heading G3N. In an arrangement for the programmed control of the position of a moving member a positional store is provided comprising an aluminium disc 1 having a surface 2 and periphery 3 coated with iron oxide, which is continuously rotated by a synchronous motor 6 and bears a permanent reference mark 4. A member, not shown, the position of which is to be recorded, angularly positions a radial arm 11 through a rack and pinion 21, 23. A position mark is recorded on the surface 2 by actuating a one-shot circuit 95 which conditions an AND-gate 93 to permit the passage of a pulse from reading head 90, due to the sensing of the reference mark 4, to a read-write head 7. The position mark has an angular position with respect to the reference mark representative of the set position of the member. The head 7 is then indexed to an adjacent track by a digital motor actuated by the one-shot circuit 95 through an OR-circuit 98 and delay circuit 99. Digital information relating to the desired direction and rate of movement of the member is stored in circuits 61-63 and transferred into tracks 45-47 of a magnetic tape 40 by heads 41-43 energized through gates 64-66 conditioned by the generation of a timing pulse from the head 44 caused by the passage of a mark 49 due to the momentary energizing of a tape driving motor 52. During playback a one-shot circuit 104 is actuated to cause the motor 52 to move the tape 40 until the next timing mark is sensed by head 44 which energizes a motor 25 and releases a brake 26 through a binary circuit 30. Simultaneously, the digital record on tracks 45-47 are read by heads 41-43 and transferred to binary circuits 31-33 to set up a directional gear 27 and 4: 1 and 2: 1 gears 28, 29. The member then moves until a pulse derived from the head 7 is coincident with a reference pulse from the head 4. The coincidence is detected by an AND circuit 101 which causes the circuits 30-31 to reset to the "0" state, thereby deenergizing motor 25, actuating brake 26 and so preparing the circuits for a new set of binary data. The circuit 101, through the OR circuit 98 and the delay circuit 99, also indexes the head 7 to an adjacent track. In a modification, a double-surfaced disc is employed and the apparatus is arranged to record a number of sequential clockwise positions on one surface and then sequential anti-clockwise positions on the other surface before the head is indexed to an adjacent track. In another modification the positional resolution, defined in terms of a resolution angle representing the range of positions the movable head could have when coincidence is detected between pulses from the movable and stationary heads, is degraded by increasing the length of pulses developed by the heads as a function of the angular speed of the movable head. This is effected by three arrangements (1) recording a plurality of closely spaced position marks dependent in number on the programmed speed (2) connecting to AND circuit 101 a variable length pulse generator controlled by binary circuits 32, 33 or (3) positioning a second head to read the reference mark 4 the separation of the heads being a function of the angular speed of the movable head 7.