# US 4,398,242 A · Electronic controller > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,398,242 A - Document ID: US4398242A - Status: Granted - Kind: A - Application number: 06/124,366 - Filed: 1980-02-25 - Granted: 1983-08-09 - Earliest claimed: 1980-02-25 - Assignees: The Boeing Company - Inventors: Henning Buus - Web page: https://patentgrep.com/patent/US4398242A ## CPC - G05D 1/0077: {using redundant signals or controls} - G05B 9/03: with multiple-channel loop, i.e. redundant control systems - G05D: SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES - G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G) ## Abstract A pair of input sense signals are processed and passed to inputs of two servo amplifiers. The amplifier outputs are summed and converted to a corresponding hydraulic pressure in a T-valve. Transducers monitor the produced pressure and provide feedback signals to the servo amplifiers. A comparator compares the servo amplifier outputs and activates a warning device if the signal difference therebetween exceeds a threshold level. Equalizer circuitry processes the comparator output and provides correction signals to the servo amplifier inputs to wash-out offset effects. ## Claims ### Claim 1 An electronic controller for producing a controlled output in response to a pair of input signals comprising: means for processing said input signals; a pair of summer means, each summer having a plurality of inputs and an output and producing an output signal equal to the summation of the signals coupled to its inputs; means for coupling each of said processed input signals to an input of one of said summers; a pair of servo amplifier means; means for coupling each summer means output to one of the servo amplifier inputs; utilization means including an actuator, said actuator responding to each output from said pair of servo amplifier means; feedback means for sensing the status of said utilization means and producing negative feedback signals to an input of each summer means such that for ideal operation of the electronic controller the output signals from said pair of servo amplifiers are identical; comparator means for comparing the two servo amplifier output signals and producing a difference signal related to the difference therebetween; threshold warning means for producing a warning indication in response to said difference signal exceeding a predetermined reference threshold; and equalizer circuitry means for processing said difference signal and applying a negative feedback correction signal to an input of each summer means thereby reducing offsets between the servo amplifier outputs due to system tolerance. ### Claim 2 An electronic controller for producing a controlled output in response to a pair of input signals comprising: means for processing said input signals; a pair of summer means, each summer having a plurality of inputs and an output and producing an output signal equal to the summation of the signals coupled to its inputs; means for coupling each of said processed input signals to an input of one of said pair of summers; a pair of servo amplifier means; means for coupling each summer means output to one of the servo amplifiers inputs; utilization means including an actuator, said actuator responding to each output from said pair of servo amplified means; feedback means for sensing the status of said utilization means and producing negative feedback signals to an input of each summer means such that for ideal operation of the electronic controller the output signals from said servo amplifiers are identical; comparator means for comparing the two servo amplifier output signals and producing a difference signal related to the difference therebetween; and equalizer circuitry means for processing said difference signal and applying a negative feedback correction signal to an input of each summer means thereby reducing offsets between the servo amplifier outputs due to system tolerances. ### Claim 3 (depends on 2) The electronic controller of claim 2 further comprising: threshold warning means for producing a warning indication in response to said difference signal exceeding a predetermined reference threshold. ### Claim 4 (depends on 1, 2) The electronic controller of either of claims 1 or 2 wherein said utilization means is comprised of an electrohydraulic means, said electrohydraulic means producing a hydraulic pressure related to the signals from said servo amplifiers. ### Claim 5 An aircraft electrohydraulic feel force generating system comprising: a pair of electronic controllers, each controller including: first and second processing means, each one of which is adapted to received signals representative of both aircraft stabilizer position and airspeed and produce a feel pressure command signal as a predetermined function thereof; a pair of summer means, each summer having a plurality of inputs and an output, and producing an output signal equal to the summation of the signals coupled to its inputs; means for coupling each feel pressure command signal to the input of one of the summer means; a pair of servo amplifier means; means for coupling each summer means output to one of the servo amplifier inputs; an electrohydraulic T-valve/manifold unit for producing a hydraulic pressure related to the output signals from the servo amplifiers; feedback means for sensing said hydraulic pressure and producing negative feedback signals to an input of each summer means such that for ideal operation of the electronic controller the output signals from the pair of servo amplifiers are identical; comparator means for comparing the two servo amplifier output signals and producing a difference signal related to the difference therebetween; threshold warning means for producing a warning indication in response to said difference signal exceeding a predetermined reference threshold; a feel and centering mechanism including a feel actuator and mechanical linkage for providing a pilot with column feel force; a pair of pressure modules, each module coupling an electronic controller output to said feel actuator; and equalizer circuitry means for processing said difference signal and applying a negative feedback correction signal to an input of each summer means thereby reducing offsets between the servo amplifier outputs due to system tolerances. ### Claim 6 An aircraft electrohydraulic feel force generating system comprising: a pair of electronic controllers, each controller including: first and second processing means, each one of which being adapted to input signals respresentative of both aircraft stabilizer position and airspeed and produce a feel pressure command signal as a predetermined function thereof; a pair of summer means, each summer having a plurality of inputs and an output, and producing an output signal equal to the summation of the signals coupled to its inputs; means for coupling each feel pressure command signal to the input of one of the summer means; a pair of servo amplifier means; means for coupling each summer means output to one of the servo amplifier inputs; an electrohydraulic T-valve/manifold unit for producing a hydraulic pressure related to the output signals from the servo amplifiers; feedback means for sensing the said produced hydraulic pressure and producing negative feedback signals to an input of each summer means such that for ideal operation of the electronic controller the output signals from the servo amplifiers are identical; comparator means for comparing the two servo amplifier output signals and producing a difference signal related to the difference therebetween; and equalizer circuitry means for processing said difference signal and applying a negative feedback correction signal to an input of each summer means thereby reducing offsets between the servo amplifier outputs due to system tolerances. ### Claim 7 (depends on 6) The system of claim 6 further comprising: threshold warning means for producing a warning indication in response to said difference signal exceeding a predetermined reference threshold. ### Claim 8 (depends on 5, 6, 7) The system of any one of claims 5 through 7 wherein the T-valve includes a mechanical bias offset for reducing the effect of a failure to a high feel pressure mode in one of the servo amplifier signal paths. ### Claim 9 An aircraft rudder ratio servo loop system comprising: an electronic controller including: first and second processing means, each processing means receiving a signal representative of airspeed and producing a command signal in response thereto; a pair of summer means, each summer having a plurality of inputs and an output and producing an output signal equal to the summation of the signals coupled to its inputs; means for coupling each command signal to the input of one of the summer means; a pair of servo amplifier means; means for coupling each summer means output to one of the servo amplifier inputs; feedback means adapted for sensing the status of a ratio changer actuator and producing negative signals to an input of each summer means such that for ideal operation of the electronic controller the output signals from the servo amplifiers are identical; comparator means for comparing the two servo amplifier output signals and producing a difference signal related to the difference therebetween; threshold warning means for producing a warning indication in response to said difference signal exceeding a predetermined reference threshold; and equalizer circuitry means for processing said difference signal and applying a negative feedback correction signal to an input of each summer means thereby reducing offsets between the servo amplifier outputs due to system tolerances; the aircraft rudder ratio servo loop system further comprising: an electrohydraulic means for producing a hydraulic pressure related to the output signals from the servo amplifiers; ratio changer actuator means responsive to said produced hydraulic pressure. ### Claim 10 (depends on 9) The system of claim 9 further comprising: a second controller being identical to said first electronic controller; and switching means responsive to the production of a warning indication of said first electronic controller to disconnect the same from controlling said ratio changer actuator and connecting said second electronic controller in the place thereof. ### Claim 11 (depends on 10) The system of claim 10 wherein the switching means further comprises: means for responding to warning indications from both the first and second electronic controllers to disable said controllers from controlling said ratio changer actuator.