GB664515A - Improvements in or relating to indicating or controlling devices - Google Patents

Abstract

664,515. Electric indicating and control systems. SMITH & SONS (ENGLAND), Ltd., S. Feb. 17, 1950. [Feb. 25, 1949] No. 5211/49. Class 40 (i). [Also in Groups XXXV and XXXVI] An apparatus for generating an electrical signal in accordance with the instantaneous value of an unknown mechanical quantity comprises' an instrument generating a first signal measuring the unknown, but lagging behind its variations, an instrument generating a second signal measuring the rate of change of the unknown with zero lag, integrating means generating a third signal which is a transient integral of the second signal with a time constant equal to the response time constant of the first instrument, and means whereby multiples of the first and third signals are added to produce a fourth signal measuring the unknown quantity without lag. In Fig. 1 a rate of climb instrument 1 comprises a reservoir 41, with a leak 42 to the atmosphere, connected to a pressure capsule 43 which deflects through a linkage the slider 49 of a D.C. energised centre tapped potentiometer 50 to produce a lagging signal measuring the rate of climb. A vertical accelerometer 3 comprises a mass 51 suspended by springs 52, 53, whose vertical movements deflect the slider of a centre tapped potentiometer 57 which is D.C. energised through ganged equal variable resistances 59, 60 in series with each leg. The resultant signal measuring the rate of change of the rate of climb is applied to an integration circuit comprising a condenser 62 in series with a variable resistance 61, adjustable to give the circuit a similar time constant to the initial measuring circuit, whose signal is added to the signal across the integrator condenser to develop a rate of climb signal without lag, which operates an indicator or controlled mechanism 5. In Fig. 2 a pitch indicator pendulum 6 and a rate of turn gyro 7 of an automatic pilot system such as that describedin Specification 6 11,037, [Group XXXV], operate the sliders of centretapped D.C. fed potentiometers 95, 76 to respectively develop a lagging pitch signal and an instantaneous rate of turn signal which is fed through a variable resistance 81 to the grid of an amplifying valve 83 operating as a Miller integrator. The anode is connected to the grid through a condenser 82, to the H.T. supply through anode resistance 85, and through potentiometer 86 to the slider of a potentiometer 87 across the supply which is adjusted so that its slider is at anode-potential when the slider of potentiometer 76 is central. The integrator is adjusted by varying resistance 81 so that its time constant is the same as that of the pitch indicator; and the lagging signal of the latter is added to the integrated rate of turn signal and the combined signal measuring the instantaneous pitch without lag together with the rate of turn signal operates a servoamplifier 101 to control a servomotor 107 which drives an elevator 112 and a tachometer generator 108 which feeds back a degenerative anti-hunt signal to the input in opposition to the rate of turn input signal.