GB1103992A - Adaptive process controller - Google Patents

Abstract

1,103,992. Automatic control. LEEDS & NORTHRUP CO. Oct. 1, 1965 [Oct. 20, 1964(2)], No. 41821/65. Heading G3R. In a system for automatically restoring a variable to a set point, the magnitudes of proportional and rate and/or integral control signals developed from an error signal are automatically modified in dependence on a further variable to produce a desired response. Boiler pressure. In Fig. 1 (not shown), a gauge 50, responsive to the pressure in a boiler 30 supplying steam to a turbine 32, actuates a potentiometer 56 in a D. C. bridge circuit 60 having a further potentiometer 64 to set a desired pressure. Output e 2 from the bridge, when boiler pressure differs from the desired value, is applied through a gain setting potentiometer 100 and an amplifier 114 to operate a servomotor 40 which corrects the pressure by adjusting a valve 36 controlling the fuel supply to the boiler. A relay 10 energized from a pulse generator 152 operates switches 10A, 10B to periodically introduce an error rate signal from an adjustable resistancecondenser network C 1 , 106 and a correction rate signal from a resistance-condenser network C 2 , 140 associated with a potentiometer 120 operated by servomotor 40. To produce a suitable modification of the response of the control system under different load conditions, a wattmeter 90, measuring the power output of a generator 94 driven by the turbine, adjusts a potentiometer 84 to vary the voltage applied to the bridge circuit and to vary the mark-space ratio of pulse generator 152 so that the rate components are effectively reduced with increase of load. Relay 10 instead of operating in an on/off manner as shown may operate between two positions which select resistance-condenser networks having different time constants. A suitable pulse generator involving a transistor-controlled integrating amplifier and single-shot circuits is described with reference to Fig. 4 (not shown). Thickness of rolled metal. In Fig. 2 (not shown), a gauge 210 responsive to metal thickness controls the vertical position of a roll 200 by means of a control system similar to that described above for boiler pressure but differing in that (a) a filter 201, described with reference to Fig. 3 (not shown), eliminates noise (b) no error rate component is provided and (c) the mark-space ratio of relay 10, which controls the correction rate signal and the time constant of the filter, is controlled by a single short circuit responsive to a contact 240 operated magnetically in dependence on the speed of travel of the metal. Analogue or digital control. A control system is described in which three adjustable components of control are produced from the error signal by (a) differentiation (b) multiplication of the error and adaptive signals and (c) multiplication of the error signal by the square of the adaptive signal and integrating the product.