| 摘要 |
<p>1,044,055. Electric selective signalling. GENERAL ELECTRIC CO. March 13, 1964 [March 14, 1963], No. 10805/64. Heading G4H. In a system for controlling the position of an object, e.g. part of a machine tool, of the kind in which a number of position indicating devices produce recurring, phase-disposed feed-back signals representing, in different denominations, the position of the object and counters controlled by the feed-back signals to give a numerical indication of the object position. The system has coarse, medium and fine control loops. Command signals from input 10, Fig. 1 (not shown); set counters 14, 15, 16, reference clock pulses (250 kes.) being applied to the counters to obtain phase displaced signals representative of the numbers in the counters. These are applied to comparators 17, 18, 19, the outputs of which are combined in converter 28 to produce a signal controlling a servomotor 29 driving the object positioning mechanism. The servo shaft is connected to a fine resolver 25 and through gearing 27 and 26 to medium and coarse resolvers 24, 23. These are supplied with reference sine and cosine waves from generator 13 which receives reference clock pulses at 250 cycles per second from counter. The outputs of the resolvers are applied shapers 20, 21, 22, each making a train of pulses phase displaced according to the position of the object. These are applied to comparators 17, 18, 19 for comparison with the input signals. The difference signal drives the servo to reduce the difference to zero. The inputs to the comparators are in the form of a differentially timed pulse for each 1000 cycles from generator 11 constituting a phase displaced recurrent pulse train. The outputs from the shapes 20, 21, 22 are applied to control the coarse, medium and fine counters. The reference counter 12 produces signals at predetermined counts. These are gated together and used to enable the medium, coarse and fine counters successively immediately before the beginning of each 1000 pulse cycle, Fig. 4 (not shown). When the corresponding differentially timed pulse occurs the counter counts the reference clock pulses until it is disabled again slightly before the beginning of the next cycle. At the end of each cycle the counters contain numbers representing in binary-coded decimal the position of the object, the values in the medium and coarse counters, since these were stopped before the end of the cycle (Fig. 4) being too small by amounts 15 and 25. These values are corrected by comparing the top decade of the fine counter with the lowest decade of the medium counter and comparing the top decade of the medium counter with the lowest decade of the coarse counter. If the values compared are different the decade belonging to the higher significance counter is corrected so that the medium and coarse counters finally indicate a position which incorporates the value in the fine counter. The final values may be visually displayed in decimal form and recorded for later use.</p> |
