Patent GB-1437003-A (GB)
Title: Programmed manipulator apparatus for assembling parts
IPC: G05B19/02
Filed: 1973-05-07
Abstract: 1437003 Grippers UNIMATION Inc 7 May 1973 [8 May 1972] 21658/73 Heading B8H [Also in Division G3] In manipulator apparatus, in which parts 80, 84 to be assembled are brought together, the former held in manipulator gripping fingers 60, 62, the parts are engaged under a bias along the axis of insertion provided by spring 46, the bias being operative when the manipulator arm has been positioned, parts 80, 84 being in abutting relation, the parts then undergoing lateral offset relative to the line of insertion until the latter takes place. As shown, known manipulator arm 24 supports bodies 34, 32, the former supporting gripping fingers 60, 62, and compressed air operated finger actuator assembly 64, 66, 68, 70, 76, and itself supported by rod-piston assembly 36, 40 for movement along the axis of insertion relative to part 32. Spring biased members 94, 96 engaging surfaces 90, 92 of bodies 32, 34 normally prevent relative motion of the latter, but whenever arm 24 reaches a programmed insertion position, energization of solenoids 98, 100 causes withdrawal of members 94, 96 to allow relative movement. Engagement operation.-As one step, in a multi-step programme, arm 24 attains a programmed insertion position, but since insertion does not initially take place, parts 80, 84 are engaged, with spring 46 compressed and lever 52 of limit switch assembly 54 in the dashed position. Limit switch contacts enable, independently of the programme stepping, either lateral offsets 190 of the arm axis, or a subprogrammed spiral search, Fig. 6 (not shown), about the insertion axis and/or the energization of vibrator assembly 122. Should parts 80, 84 include a keyway, wrist motion 28 from an extreme psoition, of arm 24 also takes place until key and keyway are aligned to allow insertion. To inhibit vibration transmission between bodies 34, 32, double U-cup seals (152, 154), Fig. la (not shown), may be provided adjacent rod and piston 36, 40. In Fig. 2 (not shown) no provision for relative movement between part 80 and arm 24 is made, part (84a) being biased for motion along the insertion axis instead. Both parts may be held in manipulator arms. Part 80 may be a cutting tool, or an article transferred to a stamping or diecasting machine. Control arrangements. (i) Use of vibration to provide lateral offsets, Fig. 3 (not shown).-When total coincidence, for all degrees of freedom of arm motion, between a programmed and actual insertion position are received, AND (574) emits a coincidence signal to OR (586) there being provision for three alternative degrees of accuracy (ACC.1-ACC.3). Since spring 46 is compressed, limit switch contact (54a) is closed, enabling vibration via relay (140) until insertion takes place, when contacts (54a) open and (54b) close to give a total coincidence signal, causing the disengagement of fingers 60, 62, and progression of the programme, which is prepared in a "teaching run", to the next step. (ii) Twisting of arm 24 for insertion of keyed parts; sub-programmed lateral offsets, Fig. 4 (not shown).-Upon attainment of total coincidence, signal (134) enables the sub-programme to either twist arm 24, or institute lateral displacements 190 of the insertion axis until insertion takes place, whereupon contact (54b) inhibits further response to the sub-programme, via diodes (192, 750, 752, 754, 756, 758) by the arm, the sub-programme being quickly run to completion enabling the next step of the main programme. Vibration simultaneously takes place, unit (14) being enabled during running of the sub-programme. (iii) Spiral traverse, Figs. 5-7 (not shown).- Upon coincidence, flip-flop (232, Fig. 5) is enabled, and, alternately increments by unity, the counts of counters (238, 240) whose counts, when odd are added to, when even, subtracted from, by complementary addition, the counts of encoders (326, 314) representing arm position in the transverse plane of (Fig. 6), the outputs of adders (248, 276) being fed to multiplex switch contacts (414, 410) appropriate to the side-to-side and down-up degrees of freedom of the arm, to control such degrees of freedom to produce the search pattern of (Fig. 6). Operation of limit switch contacts (54a, 54b, 54c) when insertion takes place reset the circuit, and enable the programme to proceed to the next step.