GB1327225A - Automatic control apparatus for adjusting an analogue output in steps - Google Patents

Abstract

1327225 Automatic control systems UZINELE ELECTRO PUTERE CRAIOVA 29 July 1970 36780/70 Heading G3R [Also in Division G4] Automatic control apparatus for adjusting the analogue output at a terminal 21 comprises a comparator 2 which receives an analogue reference input 4 and the output from terminal 21, a digital signal generator 6 receiving the analogue error signal from the comparator 2 and supplying a principal control signal when the error exceeds a positive or negative principal threshold value and a secondary control signal when the error lies between a positive or negative secondary threshold value (less than the principal value) and the principal value, reversible principal and secondary control registers 7, 8 which respectively receive the principal and secondary control signals which change the value of the analogue output at terminal 21 in equal principal and secondary steps, the latter being smaller than the former and each corresponding to a respective number in the register, and which count in a direction corresponding to the sign of the control signal so as to change the analogue output in a manner reducing the magnitude of the error signal, a decoding and control unit 18 receiving the combined output of registers 7, 8 and an analogue signal generator 20. A description is given of the characteristic of the generator 6, Fig. 2 (not shown), of the relationship between the number stored in a register, which operates in accordance with an arithmetical progression, and the number of steps, Fig. 4 (not shown) and of a typical operation of the control apparatus, Fig. 5 (not shown). Feedback channels 11, 12, 13, 14 respectively provide for changes in the number stored by registers 7, 8 when the register 8 generates a command signal (channels 11, 12), for inhibition of the generation of principal control signals when the register 7 reaches a maximum or minimum count (channel 13), and for complete inhibition of the generator 6 when both registers have reached their maximum or minimum count (channel 14). The relationship between the numbers stored by the registers during individual operations is discussed, together with an analysis of their combined capacity. The generator 6 supplies principal or secondary control signals at a substantially constant rate which is the reciprocal of the delay time of the control apparatus. A discussion is given of the relationship between the sampling action of the generator 6, a virtual error signal, a command error signal, a stable error signal and the actual error signal, all these parameters also being related to a single error threshold value, the delay time of the control apparatus and the period between successive control actions of the apparatus, Fig. 3 (not shown).