Pulse-width modulated servo torquer control whereby power drain is minimum at null

Claim 2

In an autopilot system for controlling the maneuvering of a vehicle, said system including means for generating a control signal in accordance with a desired yaw attitude of said vehicle, the improvement comprising: power drive signal generator means for generating electrical power drive in response to said control signal, said power drive signal generator means including first means for generating a first train of DC pulses having a width in accordance with yaw control signals representing yaw in a first direction and second means for generating a second train of DC pulses having a width in accordance with yaw control signals representing yaw in a second direction opposite to said first direction, said first generating means being in an off condition whenever the control signals are zero or represent yaw in the second direction, said second generating means being in an off condition whenever the control signals are zero or represent yaw in the first direction, power bridge means for receiving said pulse trains, vehicle maneuvering controls, and DC torquer means for receiving the output of said power bridge means for driving said vehicle maneuvering controls, said DC torquer means being connected to said power bridge means to receive DC current in one direction in response to said first train of pulses, and DC current in the direction opposite to said one direction in response to said second train of pulses.

Claim 3

The system of claim 1 wherein said DC torquer has a permanent magnet rotor and a stator having windings connected to receive the output of said power bridge means.

Claim 4

The system of claim 1 wherein said power drive signal generator means comprises a ramp generator for generating a ramp signal, means for generating a first signal in accordance with the control signal, means for generating a signal in accordance with the inverse of the control signal, first and second switching means, each having a control gate, an anode and a cathode, said ramp signal being fed to the anodes of said switching means, said signals in accordance with the control signal and the inverse thereof being fed respectively to the gates of each of said switching means, whereby each of said switching means is gated to produce a pulse signal whenever the ramp signal exceeds the voltage at the gate thereof.

Claim 5

The system of claim 1 wherein said means for generating a control signal in accordance with a desired yaw attitude comprises a radio navigation device, a rate of turn gyro and means for integrating the output of said gyro, and a manual turn control, and switching means for alternatively selecting the output of one of said above mentioned devices as a control signal.

Claim 6

The system of claim 3 wherein said power bridge means comprises two pairs of electronic switches connected to each other to form a bridge circuit having first and second pairs of connection points, D-C power being applied between one of said pairs of connection points, said DC torquer being connected between the other of said pair of connection points, a pulse signal in accordance with the output of one of said switching means being fed to actuate one of said pairs of electronic switches and the output of the other of said switching means being fed to actuate the other of said pairs of electronic switches.

Claim 7

The system of claim 1 wherein said power drive signal generator means further includes a differential DC amplifier for receiving said control signal and providing an output only when the input thereto goes above or below a predetermined DC reference level.

Claim 8

The system of claim 3 wherein said first and second switching means comprise programmable unijunction transistors.

Claim 9

The system of claim 3 and further including left and right control transistors responsive to the outputs of said first and second switching means respectively, said left control trAnsistor being connected to said power bridge means to provide the DC current in said DC torquer in said one direction to effect a left drive of the maneuvering controls, said right control transistor being connected to said power bridge means to provide the DC current in said DC torquer in the opposite direction to effect a right drive of the maneuvering controls.

Claim 10

An autopilot system for controlling the maneuvering of an aircraft comprising: maneuvering controls for actuating the control surfaces of the aircraft, means for generating a control signal in accordance with a desired orientation of said aircraft, power drive signal generator means for generating electrical power drive in response to said control signal, said power drive signal generator means including a ramp generator for generating a ramp signal, means for generating a first signal in accordance with the control signal, means for generating a second signal in accordance with the inverse of the control signal, first and second switching means, each having a control gate, an anode and a cathode, said ramp signal being fed to the anodes of said first and second switching means, said signals in accordance with the control signal and the inverse thereof being fed respectively to the gates of each of said switching means, whereby each of said switching means is gated to produce a pulse signal whenever the ramp signal exceeds the voltage at the gate thereof, and first and second power amplifier means responsive to the pulse signal outputs of said first and second switching means respectively, for respectively generating a first train of DC pulses having a width in accordance with desired orientation in a first direction and a second train of pulses having a width in accordance with desired orientation in a second direction opposite to said first direction, said first switching means and said first power amplifier means being in an ''''off'''' condition when the control signal is zero or represents a desired orientation in said second direction, said second switching means and said second power amplifier means being in an ''''off'''' condition when the control signal is zero or represents a desired orientation in said first direction, DC torquer means for driving said maneuvering controls, and power bridge means for receiving said pulse trains and connected to said DC torquer means to provide a DC drive current thereto in a first direction in response to the first train of pulses and in a second direction opposite to said first direction in response to the second train of pulses, thereby to drive the maneuvering controls in said first and second directions respectively.

Claim 11

An autopilot system for controlling the maneuvering of an aircraft comprising: maneuvering controls for actuating the control surfaces of the aircraft, means for generating a control signal in accordance with a desired orientation of said aircraft, power drive signal generator means for generating electrical power drive in response to said control signal, said power drive signal generator means including a ramp generator for generating a ramp signal, means for generating a first signal in accordance with the control signal, means for generating a second signal in accordance with the inverse of the control signal, first and second switching means, each having a control gate, an anode and a cathode, said ramp signal being fed to the anodes of said first and second switching means, said signals in accordance with the control signal and the inverse thereof being fed respectively to the gates of each of said switching means, whereby each of said switching means is gated to produce a pulse signal whenever the ramp signal exceeds the voltage at the gate thereof, and first and second power amplifier means responsive to the pulse signal outputs of said first and second switching means respectively, for respectively generating a first train of DC pulses having a width in accordance with desired orientation in a first direction and a second train of pulses having a width in accordance with desired orientation in a second direction opposite to said first direction, said first switching means and said first power amplifier means being in an ''''off'''' condition when the control signal is zero or represents a desired orientation in said second direction, said second switching means and said second power amplifier means being in an ''''off'''' condition when the control signal is zero or represents a desired orientation in said first direction, DC torquer means for driving said maneuvering controls, and power bridge means for receiving said pulse trains and connected to said DC torquer means to provide a DC drive current thereto in a first direction in response to the first train of pulses and in a second direction opposite to said first direction in response to the second train of pulses, thereby to drive the maneuvering controls in said first and second directions respectively.

Claim 12

The system of claim 9 wherein the system operates to control the yaw orientation of the aircraft.

Claim 13

The system of claim 10 wherein said means for generating a control signal includes a rate gyro and means for integrating the output thereof to produce a heading control, a radio navigation device, and a manual turn control and means for alternatively selecting the output of one of said aforementioned devices as a control signal.

Claim 14

The system of claim 9 wherein said power bridge means comprises two pairs of electronic switches connected to each other to form a bridge circuit having first and second pair of connection points, DC power being applied between one of said pairs of connection points, said DC torquer being connected between the other of said pair of connection points, a pulse signal in accordance with the output of one of said switching means being fed to actuate one of said pairs of electronic switches and the output of the other of said switching means being fed to actuate the other of said pairs of electronic switches.

Claim 15

The system of claim 9 wherein said power drive signal generator means further includes a differential DC amplifier for receiving said control signal and providing an output only when the input thereto goes above or below a predeterminEd DC reference level.

Claim 16

The system of claim 9 wherein said DC torquer has a permanent magnet rotor and a stator having windings connected to receive the output of said power bridge means.