Multiplexanlage mit mindestens drei parallel arbeitenden Unterkanaelen,insbesondere fuer automatische Flugregelung

1296974 Automatic control SMITHS INDUSTRIES Ltd 12 Dec 1969 [17 Sept 1968] 44071/68 Heading G3R In a control system provided with at least three channels for redundancy, excessive deviation of a signal in one channel relative to the signals in the other channels renders that channel ineffective and lesser differences, detected by separately comparing the signal in each channel with the signal in each of the other channels, are eliminated by applying the differences associated with each channel through a limiter to correct the signal in that channel. Fig. 2 shows one of three identical channels of an aircraft automatic pilot controlling common elevators or ailerons 38 from instruments 23 so as to obtain a desired pitch or roll attitude or to effect radio navigation, altitude control or automatic landing. Control signals derived from a computer 22 associated with the instruments are applied through an amplifier 28 to an AC servomotor 29 which, by virtue of feedback from a tachometer generator 31 adjusts control surfaces 38 at a rate dependent on the resultant of the other signals applied to amplifier 28. Signals from a gyro 25 responsive to rate of turn of the aircraft about the axis of control, and signals from computer 22, integrated at 50, are also applied to the imput of amplifier 28. If the torque of servomotor 29 is in such conflict with that of the servomotors in the other channels that a switch 41 is opened, a clutch 34 is de-energized to render the channel ineffective. This also happens if a unit 43, which applies test signals to amplifier 28, does not detect a corresponding amplifier output signal and opens contacts 42, or if servomotor 29 is not energized and a relay 32, associated with it, opens contacts 33. Units 45 and 46 separately compare the output of amplifier 28 with the outputs of corresponding amplifiers in the other channels and limited signals corresponding to any differences are combined at 49 and applied to the input of amplifier 28 in a sense tending to eliminate the differences. Integral components of the differences are also added by integrator 50 and the gain of the channel is also adjusted in dependence on the magnitude of the differences by applying the differences to units 51 and 24 which respectively vary the signal output of tachometer generator 31 and rate of turn gyro 25. Alternatively, unit 24 may adjust the output of computer 22 and/or unit 51 may adjust the feedback from tachometer generator 31 or the other inputs to am