Abstract: The multiple channel servo system engages in bus communication with a micro-controller, motor driver for driving a plurality of motors and motor servo for providing servo information for selected ones of the motors. The micro-controller generates respective motion command profile information for each of the selected motors. RAM is provided for receiving and storing the motion command profile information from the micro-controller for the selected motors. The servo system sequentially compares the respective servo information with the respective motor command information and generating respective motor control information for the respective motor for causing the motor driver to cause the respective motor to closely track the respective motor command profile. RAM memory is also provided for receiving and storing microcode for each of the selected motors.

Abstract: A monitoring system for detecting a fault condition in any one of multiple power control actuator units used for positioning an aircraft's control surface includes sensors for producing sense signals corresponding to the load on each actuator unit under a given control surface loading condition. The sense signals are compared with a reference level signal corresponding to a maximum allowable load. An indication is produced in response to the load on any actuator unit exceeding its allowed value.

Abstract: A servo circuit with a failure detection mechanism comprising: a servo circuit for servo controlling on the basis of a control signal an actuator which is connected through a hydraulic circuit with a source of oil pressure and is operated by the hydraulic circuit which is changed over by a servo valve; a monitor circuit arranged in parallel relationship with the servo circuit and generating a monitor control signal; and a failure detection circuit in which the control signal of the servo circuit and the monitor control signal of the monitor circuit are inputted and which detects a failure of the servo circuit on the basis of the control signal and the monitor control signal; wherein the hydraulic circuit is provided with pressure detecting means for detecting a pressure thereof; and the monitor circuit includes a correction circuit in which a pressure signal from the pressure detecting means is inputted and which corrects a loop gain of the monitor circuit in correspondence with a value of the pressure signal

Abstract: A flight control system receiving input flight control signals from a flight control computer to manipulate a flight control surface. The dual actuator has an actuating rod connected to the flight control surface, and a pair of pistons are mounted on the actuating rod in respective first and second cylinders. The flow of hydraulic fluid into and out of the first and second cylinders is controlled by the first and second electrohydraulic servovalves, respectively. The electrohydraulic servovalves are, in turn, operated by respective signals applied to a pair of actuating coils. The system includes two controllers that receive the flight control signals and apply respective output signals to the four coils of the two electrohydraulic servovalves. In one embodiment, the controllers each have a primary channel and a secondary channel which are connected to respective actuating coils of the first electrohydraulic servovalve.

Abstract: An arrangement for controlling the position of a movable member, especially an aircraft control surface member, includes an operational amplifier and a capacitor connected in parallel to the amplifier. The control arrangement further includes a detector which detects the restoration of the supply of electric power following its interruption and generates a limited-duration pulse. This pulse is then used to close a switch, which is interposed between an input terminal of the capacitor and the ground, for the duration of this pulse, so that the capacitor is charged much more rapidly than otherwise. The output signal of the combination of the operational amplifier and the capacitor is supplied to an actuator for the movable member so that the extent of excursion of the movable member out of its desired position after the electric power supply has been restored is minimized.

Abstract: A novel actuator control system is characterized by displacement sensor fault detection. The system includes linear variable phase transducer (LVPT) displacement sensors. A pair of engine electronic controls (EEC) each determines the actuator position by measuring the phase shift of the corresponding LVPT output signal with respect to the fixed phase of the LVPT excitation signal. The voltage amplitude of the LVPT output signal has a unique relationship with to the phase of the excitation signal, and is more sensitive to sensor failure than is phase shift alone. A computer in the control compares the amplitude of the LVPT output signal to upper and lower voltage limits for that displacement. Should the computer determine that the voltage amplitude of the secondary winding output signal is out of range, the system will adjust the actuator drive circuits accordingly.

Abstract: Prevention of actuator oscillation due to failure mode in an aircraft pitch axis control system is provided by an oscillatory failure monitor. The oscillatory failure monitor provides power shutdown of the actuator through inner loop modeling and error signal processing of inner loop disturbances.

Abstract: An aircraft flight control system for use with a dual or tandem hydraulic actuator coupled to a flight control surface through an actuating rod. Each half of the tandem actuator is controlled by a respective electrohydraulic servovalve. Each electrohydraulic servovalve is controlled by signals applied to either of two actuating coils. Control signals are applied to the actuating coils from three controllers. The control signals are generated as a function of the difference between the flight control signal and a feedback signal indicative of the position of the actuating rod. Each electrohydraulic servovalve includes a pair of linear variable differential transformers generating feedback signals indicative of the position of the valve stem in each electrohydraulic servovalve. The valve feedback signals are compared to each other and to reference signals corresponding to the expected value of such feedback signals in order to detect and identify malfunctions in the flight control system.

Abstract: An industrial sewing machine having a main shaft which can be driven by an electric motor drive, a positioner disposed on the main shaft, a regulating and control system controlling the electric motor drive, an operating and display system, and an interface system producing the connection between the operating and display system on the one hand and the regulating and control system on the other. Such an industrial sewing machine is to be configured such that great freedom from electrical interference will be achieved in spite of the individual connection of additional unfiltered electrical components.

Abstract: A system which measures direct current drift and noise in sensor signals from redundant sensors utilizing a parity-space algorithm. Parity vector signals produced by the parity-space algorithm are averaged to provide a direct current (DC) drift signal. An instantaneous noise signal is found by subtracting the direct current drift signal from a parity vector signal for one of the samples of the sensor signals. The RMS value of the instantaneous noise signals are averaged to provide sensors noise signals.

Abstract: This adapter has a housing containing an automatic electrical switching circuit, a plug for connecting the circuit to an external A.C. power source, and sockets for mounting primary and standby lamps on the housing in circuit with the switching circuit. The circuit includes a conventional rectifier bridge and a transistor which is normally biased off so that the standby lamp is off, when the primary lamp lights. When the primary lamp goes off (burns out), the transistor conducts and the standby lamp is automatically turned on. When the primary lamp again operates the transistor is again biased off and the standby lamp is automatically turned off. A signal lamp in the switch circuit lights when the standby lamp is on. Motors or other power consuming devices may be substituted for the lamps.

Abstract: In a device for controlling elements of a machine, comprising two control members of the joy stick type from one or other of which said elements may be controlled, these members being intended to be actuated by separate operators and each being mounted for tilting about at least one axis and connected to at least one sensor delivering an electric signal representative of the amplitude of tilt of the associated joy stick about said axis on each side of a neutral position, a signal processing system is provided receiving the signals from two sensors and delivering a single control reference addressed to said controlled elements of the machine.

Abstract: An all-electric powered flight control system for an aircraft incorporating fault-tolerant avionics combined with a redundant power actuation control system utilizing electro-mechanical devices for actuating aerodynamic control surfaces; and wherein, the redundancy is implemented through the division of the total aerodynamic surface area to be actuated into multi-segments, with each control segment having its own channel in the avionic control system. The avionic control system is effective in minimizing the effects of power actuated control loads reacting through aircraft structure by the incorporation of an electronic gain control power module which is positioned between the power output side of an actuator (e.g., an electro-mechanical or electro-hydraulic device) and the aerodynamic control surface or segment being actuated.

Abstract: The capability of compensating automatically for a failure in an actuator and the associated drive circuit is enhanced by providing a dual channel actuator, each channel having a drive coil and a position sensor tracking the position of the actuator output shaft. A separate circuit is provided for each actuator channel to detect drive loop failures and hydraulic failures. When the drive loop of one channel fails, it is disengaged, and the gain in the remaining drive loop is doubled to maintain authority. In an embodiment, the remaining drive loop cannot disengage when certain criteria, relating to the failure of associated actuators, are met. The invention is particularly useful for aerospace applications.

Abstract: A multiplex control system including a plurality of controllers, the main controller being arranged by hardware, while the subsidiary controller being accomplished by software. Each of the controllers has a PID operator for calculating the proportional, differential and integral components of process data, and the difference of the integral components of both PID operators is processed through a first-order time lag operator and the result is used to correct the error of the output from the PID operator of the subsidiary controller. In the occurrence of abnormality, control of the control object is switched from the main controller to the subsidiary controller using the first-order time lag element attached to the switch unit thereby preventing the tracking of control data.

Abstract: Each wing of an aircraft carries a set of five outboard spoilers, one inboard spoiler, one inboard aileron and one outboard aileron, together constituting the lateral control surfaces for the aircraft. Each spoiler is positioned by means of a single thread electrohydraulic servoactuator. Each outboard aileron is positioned by means of a one/one fail-operational electrohydraulic servoactuator. Each inboard aileron is positioned by a two/one fail-operational, electrohydraulic servoactuator. The control system is operated by four independent electrical control signal processing channels and four independent hydraulic pressure supplies.

Abstract: Each of several redundant sensor signals is compensated with respect to a midvalue selected signal in equalizer circuitry. A midvalue selector selects the midvalue one of the compensated input signals. Fault detection circuitry identifies as a failure any compensated input signal which deviates from the midvalue selected signal by a specified limit and, in response thereto, insolates the identified signal and substitutes therefor as an input to the midvalue selector the selected midvalue signal.

Abstract: A redundant actuator system in which some of the sub-actuators have a lower force capability than the other sub-actuators. The lower force capability sub-actuators are controlled by a common electrical control circuit while the other sub-actuators are each independently controlled by separate control circuits. A plurality of hydraulic supplies power the sub-actuators, each supply powering one lower force capability sub-actuator, and at least one other sub-actuator.

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.

Abstract: A controller (FIGS. 1, 2) is provided in a dual servo system that drives a controlled element (22) with mechanically coupled first and second servos (24 and 44). This controller has a first (10, 110, 112) and second (14, 108, 114) digital process subsystem. The first digital processing subsystem can simultaneously drive the first and second servos. This first processing subsystem is operable to measure the responsiveness of the servos to the first processing subsystem and provide a self-checking indication. The second digital processing subsystem measures the responsiveness of these servos to the first digital processing subsystem and can provide an independent indication of failure. The foregoing can be extended to multiple channels for controlling independent multiple elements such as aircraft control surfaces. Preferably, two different types of computers (10, 14; 108, 110, 112, 114) with different programs can be employed to control three control channels.

Abstract: Disclosed is a method of and apparatus to facilitate the operation of two servoactuators with a two/one (2/1) fail operational capability. In preferred embodiments, four signal processing channels are provided, two of which are active and directly control hydraulic servovalves which in turn controls the rate of operation of the servoactuators. Two other modeling channels produce an electrical output similar to the output expected from the servoactuator when supplied with the input to the active channel. The two actual rate indicative outputs and the two modeled rate indicative outputs are compared and deviations in one channel from the other three cause that channel to be declared a "failed" channel. Through a logical switching system, if an active channel has failed, the output of its associated model channel is connected to the servoactuator to continue operation of that actuator.

Abstract: Self monitored process control device comprising two complementary circuits (4,5) allowing control signals to be replaced when erroneous, by safety limit values computed by separate circuits (10,11,17,18), a circuit (21) sending a warning signal when signals at the output of the two complementary circuits (4,5) are not identical, a safety circuit (23) permitting selection of the healthy signal from the two complementary circuits (4,5) upon failure of one of the complementary circuits (4,5) and a monitoring circuit (26,28,29) allowing a failure of the safety circuit (23) to be indicated. The invention applies especially to aircraft flight control.

Abstract: Input signals from sensor (S) in a redundancy management system are provided redundantly in parallel so that a primary control signal may be selected. Median value signals for groups of three sensors are detected in median value selectors (30, 32, 34, 36, 40) of selection filters (F). The detected median value signals are then also compared in a subtractor/comparator (38) to determine whether any of them exceed the others by an amount greater than the signal level for a failed sensor. If so, the exceeding detected medium value signal is sent to a control computer (10) as the primary control signal. If not, the lowest level detected medium value signal is sent as the primary control signal.

Abstract: The main roll and yaw axes of a helicopter having a main rotor operative in response to cyclic and collective pitch commands and a tail rotor operative in response to pitch commands, include stability inputs to actuators which are selectively provided by an analog channel, a digital channel, or one half by each, the digital channels being manifested in a digital computer system which includes programs of self-test, in-flight comparison between the inputs and outputs of corresponding analog and digital channels, and ground tests of testable rate gyro inputs to the various digital and analog channels and the outputs thereof.

Abstract: A helicopter elevator (12, 13) is driven by an electrical actuator (20) to position the elevator (12, 13) to an optimum angle of incidence for given flight conditions. The actuator (20) is included within a servo loop which responds to a command signal derived from an electronics module (69). Transducers which measure longitudinal cyclic position (40), collective pitch position (41) and air speed (42) generate signals which are summed in a summation unit (43). The output of the summation unit (43) is passed through a signal multiplier (45) which has the gain thereof set inversely proportional to air speed. A trigger unit (56) activates the signal multiplier (45) at an air speed above a preset threshold. An integrator (54) integrates the sum of the outputs of the longitudinal cyclic position transducer (40) and air speed transducer (42) to compensate for different center of gravity aircraft loadings.

Abstract: Multiple redundant sensor signals are processed through an equalizing and selecting network which outputs the midvalue signal and eliminates all null offsets occurring among signals. Errors due to drift in a signal are minimized by bounding the output to the limits of the remaining redundant signals. Faults of both a high and low frequency nature are detected resulting in the isolation of the appropriate signal channel.

Abstract: A digital flight guidance system includes a pair of processors, each with its own memory means and arranged with common input and output means for providing monitored guidance of an aircraft when the craft is in cruise modes or when the craft is performing a critical maneuver such as landing, terrain following, or the like.

Abstract: Apparatus for controlling channel equalization in a monitored dual servo channel aircraft automatic flight control system, in which the limits of the equalization control are responsive to the commanded input signal to the control surface. Rate feedback means responsive to the output velocity of each channel are differentially summed and integrated to provide the signals for equalizing the dual servo channels. Limiter means responsive to the commanded input signal varies the limits of the equalization signals to allow very tight error detection thresholds of the system monitor without causing nuisance trips in situations where the system's normal tolerances are large.

Abstract: The invention is directed to a supervisory circuit for a control system of the type having a plurality of redundant input channels and a single output channel. More specifically, the invention is directed to a supervisory circuit for a two-channel redundant control system that provides reliability approaching that of a three-channel system. The supervisory circuit operates on the assumption that the majority of control circuit failures are catastrophic. The supervisory circuit includes a channel select circuit that receives the outputs of both of the identical control circuits and determines the faulted channel. Determination of the faulted channel is accomplished by a two-step comparison. In the first step, the outputs of both channels are compared with a previously stored output, or average of previous outputs. In the second step, signals representative of the absolute difference between each channel output and the stored output are compared.

Abstract: A control system for controlling displacement of the aerodynamic control-surfaces of an aircraft includes a first signal processor that is supplied with input signals from the pilot's control column and also with predominantly lower-frequency components of feedback signals derived in accordance with the actual position of the control surfaces. The first signal processor derives an intermediate signal from the input and feedback signal components by digital processing and supplies this intermediate signal to a second signal processor which also receives the predominantly higher-frequency components of the feedback signal. The second signal processor derives an output signal from the intermediate and feedback signal components by analogue processing and supplies this to an actuator for controlling displacement of the control-surfaces. The second signal processor may also receive additional feedback signals directly from the actuator.

Abstract: The servomotor outputs of two substantially identical servo channels, are connected through a differential mechanism to position an attitude control surface of an aircraft in response to common or separate, normally identical, command signals applied to the respective channels. Position and rate feedback means responsive to the movement of the control surface and each servomotor provides position and rate feedback signals to their respective channels. The primary position rate feedback term for each servomotor channel is derived from the position feedback means rather than from a servo tachometer to increase the stiffness of the output in resisting the motions commanded by a failed servo channel and to improve fault detection capability by increasing the difference velocity between a good and a failed channel.

Abstract: The dual electromechanical servo actuator comprises two electric servo motors coupled through differential gearing to position an output member in accordance with an input signal. Tachometer generators coupled to the respective output shafts of the servo motors, (and normally integral with the motors) provide rate feedback signals to the respective inputs of the servo amplifiers driving the respective motors. An electronic model of the dual servo actuators responsive to the input signal provides a rate signal simulating the tachometer responses to the input signal. A monitor compares the two tachometer signals and provides a failure signal when the difference therebetween exceeds a predetermined threshold. The monitor also simultaneously compares the model rate ouptut with the individual tachometer signals to determine which of the two servo channels has failed. The monitor circuits apply a brake to the servo motor output shaft of the failed channel.

Abstract: A quadruplex, double-failure survival, fly-by-wire aircraft control system includes two monitor lanes whose outputs are consolidated with those of the four main control lanes to drive the aircraft control-surfaces by hydraulic rams via individual spool-valve actuators. Nominally-identical sets of pilot's-demand, instrument, and position-feedback signals are derived independently for the four lanes respectively, and digital representations of all these are exchanged between the control lanes for the selection of their mean or median values by digital processors that also serve to compute the control outputs of the lanes from the selected values. The sets of signals supplied to one pair of the four lanes are reversed in sense compared with the sets supplied to the other pair so as to ensure that the same digitally-encoded data is represented differently in the different pairs and the possibility of a context-dependent failure occurring simultaneously in both pairs is thereby avoided.

Abstract: An in-line actuator monitoring apparatus utilized in a redundant actuator system for determining which of the two redundant secondary actuators in a flight control system has failed and providing a disable signal to the failed actuator unit.

Abstract: A dual channel, fail-operative automatic flight control system is disclosed in which each channel includes a totally monitored digital computer for operating upon sensor input data to provide command signals to the aircraft surface control actuators. The operative program for each computer is repetitively executed to effectively provide continuous control. The program is organized into a plurality of tasks to be performed by the computer with program segments associated with the respective tasks and a program routine for determining that all of the tasks have been completed for each program iteration. If non-completion of a task is detected, the program enters a failure routine which stops execution of the program. The program also includes a routine for generating a dynamically varying pattern in accordance with the continuously reiterated execution of the program.

Abstract: A secondary circuit identical to the primary arithmetic circuits is provided for an anti-skid electronic control system. The outputs of the secondary and primary circuits are connected in a predetermined manner to a comparator arrangement. If an error occurs in the secondary and/or primary circuits, the comparator will detect the error and render the entire anti-skid system inoperable.

Abstract: Apparatus for signal selection and signal consolidation of the redundant sensor signals in a triply redundant control system wherein one of the redundant sensors supplies precise information and the remaining two sensors supply less precise information is disclosed. Signal selection is based on the operational state of the three sensors, with the signal provided by the precision sensor being selected whenever the precision sensor is operational. If the precision sensor fails, each channel is supplied with a signal that is a weighted average of the signals supplied by the two less accurate sensors. In some arrangements of the invention whenever the precision sensor has not failed, but supplies a signal that deviates substantially from the signals being supplied by the two less accurate sensors, the signal supplied to each channel of the control system is a weighted average of all three sensor signals.

Abstract: A fail safe aircraft control system wherein duplicate control loops are employed to produce identical control signals for the system actuator. Output signals from the two loops are compared to detect when the outputs differ by a preset limit as an indication of a component failure. When such a failure is detected the system actuator is deactivated thus preventing the failed augmentation system from affecting control of the aircraft.

Abstract: The servomotor outputs of two substantially identical servo channels, are connected through a differential mechanism to position an attitude control surface of an aircraft in response to common or separate command signals applied to the respective channels. The dual channels are continuously monitored in such a manner that if the velocities and accelerations of the two servomotor outputs do not track each other within predetermined ratio limits, appropriate servo brakes will clamp the output of the servomotor with the highest acceleration, or the failed channel. The rapidity with which the failed channel is detected and the servo brakes applied assures that essentially no control surface motion occurs and hence no attitude or flight path transients are evident by reason of the failure. Clamping of the failed servomotor, moreover, assures that the remaining servo channel may remain operative.

Abstract: A redundant channel control system includes one or more voters having a high-pass filter connected between a pair of voter inputs.

Abstract: In a servocontrol device for controlling a control surface of an aircraft, which device is associated with a mechanical control member such as control column, wheel, pedals, and which comprises two identical double-acting hydraulic rams, integral with each other and each controlled by means of a slide valve, the slide valves each being controlled by a servovalve, whilst each servovalve is controlled by an electrical chain associated therewith, emitting an electrical control signal taking into account the displacements of said control member, the chains are connected to each other by crossed connections and they comprise apparatus for delivering equal signals to said servovalves.The invention is directed to the control of the control surfaces of an aircraft.

Abstract: Two substantially identical servo channels, coupled through a differential mechanism, position an attitude control surface of an aircraft in response to a common command signal applied to both channels. The common command is coupled to each channel through separate displacement and rate limiting devices to limit the attitude displacement and rate of change of attitude commands about the associated aircraft axis. In the pitch axis a separate normal accelerometer controls each command rate limit so as to prevent excessive pitch maneuvers due to the common command source.

Abstract: Control apparatus for controlling an aircraft gas-turbine engine, having two control lanes operated in parallel with one another and each of which is capable of performing the function of the control apparatus individually, includes a computer and a monitor unit associated with each lane for performing checks on the integrity of the components of both lanes. Transducers in each lane sense engine parameter values and pass signals in accordance therewith to the computer that sends control signals to a control unit and thence to an actuator for adjusting engine variables in accordance with engine-thrust requirements. The control unit includes a pair of cam-operated switches that respond to difference in the values of the control signal from each lane indicative of a fault in the lanes and that trigger operation of the monitor unit in each lane.

Abstract: Variable current generator arrangement for controlling the position of remote load components allowing replacement of a main control current generator by an auxiliary control current generator. The main control current generator is a current injector with high output impedance. The auxiliary control current generator is a voltage follower with low output impedance. For performing switchover, a switch means allows the voltage across the load component to be applied to an analog store means and the voltage in said store means to be applied to the voltage follower.

Abstract: Apparatus for monitoring a redundant multi-channel analog system and for the forming of an undisturbed mean signal value in which all channels are connected to the inputs of a maximum value selection device and a minimum value selection device with a mean value former having as inputs the signals in all channels and the inverted extreme value signals detected by the two devices.

Abstract: Disclosed is a plurality of motors mechanically connected in series so as to provide operational redundancy. The shaft of a given motor is rigidly attached to the housing of the next motor in the series, so that rotation of the first shaft will cause the second motor and its shaft to rotate. Means are provided to prevent relative rotation of the rotors of the redundant motor(s). Other means are provided to detect failure of the operating motor and to activate another motor in the series when this occurs.