Model-following control system using acceleration feedback

• US 6,189,836 B1
• Filed: 09/25/1998
• Issued: 02/20/2001
• Est. Priority Date: 09/25/1998
• Status: Expired due to Fees

• Current Assignee: Sikorsky Aircraft Corporation (Martin Marietta Corporation)
• Original Assignee: Sikorsky Aircraft Corporation (Martin Marietta Corporation)
• Inventors: Mayo, John Randall, Gold, Phillip Jeremy
• Primary Examiner(s): Eldred, J. Woodrow
• Application Number:
  US09/160,598
• Time in Patent Office: 879 Days
• Field of Search: 244/76.C, 244/191, 244/76.R, 244/181, 244/183, 244/184, 244/17.13, 244/177, 701/4, 701/10
• US Class Current: 244/191
• CPC Class Codes: G05D 1/0816 to ensure stability
• CPC Class Codes: G05D 1/0858 specially adapted for vertical take-off of aircraft

Abstract

A feedback system for reducing the effects of destabilizing forces in a vehicle (e.g. helicopter) by utilizing acceleration feedback data sensed by an acceleration sensor located in the vehicle. This sensed acceleration signal is passed through a low-pass filter and combined with a command signal to produce an error signal. The error signal is multiplied by a predetermined gain to produce a corrective signal that is utilized by actuators to adjust an adjustable surface, such as a swashplate, on the vehicle.

Claims

1. A system for controlling the effects of destabilizing forces comprising:

a vehicle having an adjustable actuator;

an accelerometer mounted on the vehicle for generating at least one acceleration feedback signal, the acceleration feedback signal being a function of vehicle motion;

a command signal circuit, coupled to the vehicle for receiving pilot command signals and producing command signals that are a function of the pilot command signals;

an accumulation circuit, coupled to the command signal circuit and the accelerometer for receiving a first command signal and at least one acceleration feedback signal and for summing the first command signal with at least one acceleration feedback signal thereby producing an acceleration error signal, that represents the difference between roll acceleration response of the vehicle and the pilot command signals;

an amplifier, having a predetermined gain, coupled to the accumulation circuit, for multiplying the acceleration error signal by the predetermined gain thereby producing an amplified acceleration error signal that represents the compensation necessary to cancel undesired roll motion of the vehicle;

a first summing circuit, coupled to the amplifier and to the command signal circuit for summing the amplified acceleration error signal from the amplifier with a second command signal that is output from the command signal circuit thereby producing a composite output signal;

a feedforward command circuit coupled to the command signal circuit for generating a feedforward command signal; and

a second summing circuit coupled to the feedforward command circuit that combines the feedforward command signal and the composite output signal to produce a corrective signal that is transmitted to the actuator.

2. The system of claim 1 further comprising:

a low pass filter coupled to the accumulation circuit and the accelerometer for receiving the at least one acceleration signal and passing substantially all signals that do not exceed a predetermined frequency to the accumulation circuit.

3. The system of claim 2 further comprising:

a plurality of sensors, mounted on the vehicle, for generating signals relating to vehicle motion; and

an attitude vector circuit, coupled to the command signal circuit and the sensors, for receiving as input, a third command signal from the command signal circuit and an attitude feedback signal from the sensors;

wherein the attitude vector circuit processes the third command signal input and the attitude feedback signal from the sensors and outputs an attitude error signal, corresponding to the vehicle attitude, to the first summing circuit;

wherein the first summing circuit utilizes the attitude error signal to produce the composite output signal.

4. The system of claim 2 further comprising:

a plurality of sensors mounted on the vehicle for generating signals relating to vehicle motion; and

a third summing circuit, coupled to the command signal circuit and the vehicle, for summing a fourth command signal received from the command signal circuit and a rate feedback signal received from the sensors thereby producing a rate error signal;

wherein the first summing circuit utilizes the rate error signal to produce the composite output signal.

5. The system of claim 1 wherein the feedforward command signal is a function of a stability signal and a trim break frequency.

6. The system of claim 2 wherein the vehicle comprises a helicopter and the actuator is coupled to a swashplate.

7. The system of claim 6 wherein the helicopter includes a bearingless main rotor.

8. A method for reducing destabilizing forces of a vehicle comprising the steps of:

generating acceleration feedback signals corresponding to sensed vehicle motion;

generating a plurality of command signals corresponding to pilot input commands;

summing at least one of the acceleration feedback signals and a first command signal thereby producing an acceleration error signal representative of the difference between roll acceleration response of the vehicle and the pilot command signals;

multiplying the acceleration error signal by a gain to produce an amplified acceleration error signal representative of the compensation required to cancel undesired roll motion of the vehicle;

summing the amplified acceleration error signal and a second command signal to produce a composite output signal;

summing the first command signal with a trim break frequency signal to produce a resulting signal;

summing the resulting signal with a stability derivative signal to produce a feedforward command signal;

summing the feedforward command signal and the composite output signal to produce a corrective signal; and

outputting the corrective signal to the actuator thereby causing the actuator to change position in response to the corrective signal.

9. The method of claim 8 further comprising the step of:

filtering the acceleration feedback signals received from the vehicle to remove substantially all signals that exceed a predetermined frequency thereby producing a low frequency signal.

10. The method of claim 9 further comprising the steps of:

generating rate feedback signals based on sensed vehicle motion;

summing one of the rate feedback signals and a third command signal to produce a rate error signal;

outputting the rate error signal to a summation circuit for producing the composite output signal.

11. The method of claim 9 further comprising the steps of:

generating an attitude feedback signal based on sensed vehicle motion;

summing one of the attitude feedback signals and a fourth command signal to produce an attitude error signal;

outputting the attitude error signal to a summation circuit for producing the composite output signal.

12. An apparatus for reducing destabilizing effects in a vehicle comprising:

at least one actuator, mounted on the vehicle, for controlling movement of at least one portion of the vehicle;

a microcomputer coupled to the at least one actuator for receiving input signals therefrom and transmitting output signals thereto;

at least one accelerometer coupled to the microcomputer and mounted on the vehicle for sensing motion of the vehicle and transmitting acceleration feedback signals to the microcomputer;

at least one control device coupled to the microcomputer for generating control signals corresponding to at least one pilot command and transmitting the control signals to the microcomputer; and

a feed forward command circuit, coupled to the microcomputer, for generating feedforward command signals,

wherein the microcomputer utilizes the acceleration feedback signals received from the at least one accelerometer, the feedforward command signals received from the feedforward command circuit and the control signals received from at least one control device to generate an output signal and transmits the output signal to the at least one actuator for adjusting the at least one actuator.

13. The apparatus of claim 12 further comprising:

a plurality of sensors, coupled to the microcomputer and mounted on the vehicle, for sensing motion and transmitting one or more rate feedback signals to the microcomputer;

wherein the microcomputer utilizes the one or more rate feedback signals received from the sensors to generate the output signal.

14. The apparatus of claim 13 wherein the plurality of sensors transmit one or more attitude feedback signals, corresponding to sensed vehicle attitude to the microcomputer;

wherein the microcomputer utilities the one or more attitude feedback signals received from the sensors to generate the output signal.

15. The apparatus of claim 12 wherein the vehicle comprises a helicopter and the actuator is coupled to a swashplate.

16. The apparatus of claim 15 wherein the helicopter includes a bearingless main rotor.

17. A method for reducing destabilization effects in a vehicle comprising:

generating a plurality of command signals from pilot input corresponding to desired vehicle motion;

generating an acceleration feedback signal corresponding to vehicle motion sensed by at least one non-pilot controlled sensor;

generating an acceleration error signal representative of the sum of a first command signal and the acceleration feedback signal, the acceleration error signal indicative of the difference between a roll acceleration response and the command signals from the pilot input;

multiplying the acceleration error signal to produce an amplified acceleration error signal representative of compensation necessary to cancel undesired roll motion of the vehicle;

combining a second command signal with the amplified acceleration error signal to produce a composite signal;

generating a feedforward signal from a feedforward circuit;

combining the feedforward signal with the composite signal to produce a corrective command signal;

outputting the corrective command signal to an actuator; and

adjusting the actuator in response to the corrective command signal transmitted to the actuator.

18. The method of claim 17 further comprising:

generating a rate command signal corresponding to pilot input;

generating a rate feedback signal corresponding to sensed vehicle motion;

generating a rate error signal that represents the sum of the rate command signal and the rate feedback signal;

summing the acceleration error signal and the rate error signal to produce the composite signal.

19. The method of claim 17 further comprising:

generating an attitude command signal corresponding to pilot input;

generating an attitude feedback signal corresponding to sensed vehicle motion;

generating an attitude error signal that represents the sum of the attitude command signal and the attitude feedback signal;

summing the acceleration error signal and the attitude error signal to produce the composite signal.

20. The method of claim 17 wherein the feedforward command signal receives input corresponding to vehicle stability.

21. A method for generating an acceleration error signal in a flight simulation apparatus comprising:

generating an acceleration feedback signal corresponding to the flight simulated apparatus motion;

generating a command signal corresponding to a pilot input;

generating an acceleration error signal representative of the sum of the acceleration feedback signal and the command signal;

generating a feedforward signal from a feedforward circuit;

combining the feedforward signal and the acceleration feedback signal to produce a corrective signal; and

utilizing the corrective signal to determine flight path stability of the flight simulation apparatus.