Fluidic approach power compensator control system

Apparatus for fluidically controlling adjustable fuel delivery means which supply fuel flow to the engine of an aircraft during landing approach operation thereof whereby the power generated by the engine is automatically controlled through a preselected schedule during landing approach, comprising:

• sensing means for sensing a plurality of aircraft flight parameters including angle of attack of the aircraft, aircraft acceleration normal to the direction of flight thereof, and position of the elevator of the aircraft;
• generating means operably coupled with said sensing means for generating fluidic parameter signals in relation to said sensed parameters;
• combining means operably coupled with said generating means for fluidically combining said fluidic parameter signals in a preselected manner into a single fluidic signal indicative of a desired rate of fuel flow to the engine for developing power in accordance with said preselected schedule;
• feedback means operably coupled with said fuel deliverly means for generating a fluidic feedback signal in relation to the actual rate of fuel being delivered to said engine;
• comparing means operably coupled with said feedback means and said combining means for fluidically comparing said single fluidic signal and said fluidic signal, and for producing a fluidic error signal indicative of the difference between said actual rate of fuel flow and said desired rate of fuel flow;
• and
• actuator means operably coupled with said comparing means and said fuel deliverly means for adjusting said fuel delivery means to alter said actual rate of fuel flow in relation to said fluidic error signal whereby said engine develops power in accordance with said preselected schedule.

A method of fluidically generating a dual mode fluidic output signal in relation to a fluidic input signal, comprising the steps of:

• fluidically generating a substantially square wave pressure differential signal;
• fluidically attenuating said square wave signal to produce a trapezoidal signal;
• impressing said input signal upon said trapezoidal signal to bias said trapezoidal signal;
• and
• driving a fluidic digital amplifier with said biased trapezoidal signal to produce a dual mode square wave output signal whose width is modulated relative to said input signal, said dual mode output signal having a proportional time average value proportional to the magnitude of said input signal whenever said input signal is less than a preselected magnitude, and having a predetermined digital time average value independent of the said magnitude of said input signal whenever said input signal is greater than said preselected magnitude.

A method of driving a fluid pressure responsive member from its actual position to a desired position, comprising the steps of:

• producing a fluidic input signal and a fluidic feedback signal respectively indicative of said desired and actual positions;
• comparing said input and feedback signals and producing an error signal therefrom whose magnitude is indicative of the difference between said actual and desired positions;
• fluidically generating a substantially square wave pressure differential signal;
• fluidically attenuating said square wave signal to produce a trapezoidal signal;
• impressing said error signal upon said trapezoidal signal to bias said trapezoidal signal;
• driving a fluidic digital amplifier with said biased trapezoidal signal to produce an oscillatory dual mode square wave output signal whose time average value is proportional to the magnitude of said error signal whenever said error signal is less than a preselected magnitude, and whose time average value is of a predetermined magnitude independent of the magnitude of said error signal whenever said error signal is greater than said preselected magnitude;
• and
• driving said member from its actual position towards its desired position in relation to said time average value of the dual mode output signal, whereby said member is respectively driven by proportional and by digital pressure differential signals whenever said difference between the actual and desired positions is less than and greater than a preselected amount.

Apparatus for driving a fluid responsive member from its actual position toward a desired position, comprising:

• signal means for producing a fluidic pressure differential error signal whose magnitude is indicative of the difference between the actual position and the desired position of said members;
• square wave means for generating a fluidic, time varying, square wave differential pressure signal;
• attenuating means operably coupled to said square wave means for attenuating said square wave signal into a time varying, substantially trapezoidal signal, said signal means being operably coupled with said attenuating means whereby said error signal biases said trapezoidal signal;
• fluidic power amplifier means driven by said biased trapezoidal signal to produce a dual mode square wave power output signal from said amplifier means whose width is modulated relative to said error signal, whereby said dual mode power output signal has a time average value proportional to said error signal whenever the latter is less than a preselected magnitude, and has a predetermined time average value independent of the magnitude of said error signal whenever the latter is greater than said preselected magnitude;
• and
• connecting means operably connecting said power amplifier means with said member whereby said member is driven from its actual position toward said desired position by said dual mode power output signal in relation to said time average value of said dual mode power output signal.

A method of selectively changing the gain of fluidic amplifier means having a pair of input signal ports, comprising the steps of:

• impressing a fluidic pressure differential input signal across said pair of input signal ports;
• providing a plurality of resistive networks associated with said input ports;
• and
• selectively varying the impedance of said resistive networks to selectively change the gain of said fluidic amplifier means,
• said resistive networks each comprising a plurality of fixed flow restrictors arranged in parallel relationship, said varying step including selectively switching fluidic monostable gates respectively located in series relationship with at least one said restrictors in each of said resistive networks.

A method of selectively changing the gain of fluidic amplifier means having a pair of input signal ports and a pair of output signal ports, comprising the steps of:

• impressing a fluidic pressure differential input signal across said input ports through a first pair of resistive networks;
• communicating said output ports with said input ports through a corresponding second pair of resistive networks in parallel relationship with said input signal;
• and
• selectively varying the impedances of said first and second pairs of resistive networks to selectively change the gain of said fluidic amplifier means.

Apparatus for selectively changing the gain of a fluidic amplifier means having a supply part adapted to be connected to a source of fluid pressure, a pair of input signal ports, and a pair of output signal ports, comprising:

• input signal means including a pair of input conduits communicating with said input signal ports for impressing a fluidic pressure differential input signal upon said input ports;
• a pair of feedback conduits interconnecting said output signal ports with said input signal ports in parallel relationship with said pair of input conduits;
• a fluidic resistive network in each of said feedback conduits and in each of said input conduits;
• and
• impedance changing means operably coupled with both said pair of input conduits and said pair of feedback conduits for selectively changing the impedances of the resistive networks associated with said input conduits and said feedback conduits to accordingly change the gain of said amplifier means.

A fluidic integrator comprising:

• a plurality of fluidic amplifiers operably interconnected to present a cascade of amplifiers having first and second input ports, and first and second output ports;
• input signal means for impressing a fluidic pressure differential input signal upon said first and second input ports;
• first and second fluidic capacitors each comprising a hollowed casing and a movable diaphragm dividing the interior of said casing into input and output variable volume chambers;
• first and second ducts respectively communicating said first and second output ports with said output chambers of the first and second capacitors, whereby fluid pressure in said first and second output ports respectively drive said diaphragms of the first and second capacitors;
• third and fourth ducts respectively interconnecting said input chambers of said first and second capacitors with said first and second input ports in parallel relationship with said input signal means;
• and
• biasing means in said input chambers of the first and second capacitors for producing a force opposing said fluid pressure in said first and second output ports, whereby said diaphragms move and said third and fourth ducts deliver a negative feedback pressure differential signal to said input ports in relation to the rate of change of pressure in the output ports such that the pressure differential signal generated across said output ports is a time integration function of said input signal.

A fluidic integrator comprising:

• a plurality of fluidic amplifiers operably interconnected to present a cascade of amplifiers having first and second input ports, and first and second output ports;
• input signal means for impressing a fluidic pressure differential input signal upon said first and second input ports;
• first and second fluidic capacitors each comprising a hollowed casing and a movable diaphragm dividing the interior of said casing into input and output variable volume chambers;
• first and second ducts respectively communicating said first and second output ports with said output chambers of the first and second capacitors, whereby fluid pressure in said first and second output ports respectively drive said diaphragms of the first and second capacitors;
• third and fourth ducts respectively interconnecting said input chambers of said first and second capacitors with said first and second input ports in parallel relationship with said input signal means;
• biasing means in said input chambers of the first and second capacitors for producing a force opposing said fluid pressure in said first and second output ports, whereby said diaphragms move and said third and fourth ducts deliver a feedback pressure differential signal to said input ports in relation to the rate of change of pressure in the output ports such that the pressure differential signal generated across said output ports is a time integration function of said input signal;
• and
• a pair of monostable gates interposed between an adjacent pair of said amplifiers in said cascade, said gates being selectively fluidically actuated to interrupt fluid flow through said cascade.

A method of integrating a fluidic pressure differential signal, comprising the steps of:

• impressing a flluid pressure differential signal upon first and second input ports of a cascade of fluidic amplifiers, said cascade having first and second output ports;
• providing first and second negative feedback loops respectively between said first input and output ports and said second input and output ports;
• interposing respective first and second fluidic capacitors in said first and second feedback loops whereby associated input and output variable volume chambers formed by a movable diaphragm therebetween in each of said capacitors respectively communicate with said input ports and output ports of said cascade;
• driving said diaphragms by fluid pressure in the associated output port to displace fluid from the associated input chamber;
• and
• biasing said diaphragms against movement in response to said pressure in the output ports to effect delivery of a pressure signal to said input ports in relation to rate of change of pressure in said output ports such that the fluid pressure differential developed across said output ports is a time integral function of said input signal.