System for control of active system for vibration and noise reduction

• US 6,402,089 B1
• Filed: 03/02/2001
• Issued: 06/11/2002
• Est. Priority Date: 03/02/2001
• Status: Expired due to Fees

• Current Assignee: General Dynamics Advanced Information Systems Incorporated (General Dynamics Corporation)
• Original Assignee: General Dynamics Advanced Technology Services Incorporated
• Inventors: Silverberg, Michael H., Kiss, John C.
• Primary Examiner(s): Poon, Peter M.
• Assistant Examiner(s): Collins, Timothy D.
• Application Number:
  US09/798,420
• Time in Patent Office: 466 Days
• Field of Search: 181/207, 181/208, 181/209, 248/638, 248/550, 367/190, 244/1.N, 244/1.R, 244/17.27, 244/54, 188/378, 267/136
• US Class Current: 244/17.27
• CPC Class Codes: B64C 2220/00 Active noise reduction systems
• CPC Class Codes: B64C 27/001 Vibration damping devices

Abstract

An adaptive controller is used to adaptively generate vibration cancellation signals driving a controlled device which effects an associated vibration and noise-producing plant. The adaptive controller has multiple control paths to generate the control signal. In a vibration attenuation control path(s), an adaptive control signal is generated by plant compensation and adaptive filtering techniques to cancel vibrations. In a position control, saturation prevention path, the available operational extents of the controlled device are monitored and compensation signals are generated which direct the movement of the controlled device in such a manner as to prevent the controlled device from reaching the extents of control. The control signals from the multiple paths are then combined and transmitted to the controlled device which alters in some fashion the noise and vibration being generated or transmitted by the associated vibrating plant.

Claims

1. A control system for reducing vibration generated by a vibrating plant including a vibrating component, a structure and a mount for mounting the vibrating component to the structure, the control system comprising:

a. means for producing controlled vibrations within the mount;

b. at least one sensor for sensing the current position of the controlled vibration producing means and developing a signal indicative thereof;

c. at least one sensor for sensing the vibration being transmitted through the mount from the vibrating component to the structure and developing a signal indicative thereof;

d. at least one sensor for sensing at least one of the characteristic frequencies at which the vibrating plant operates and developing a signal indicative thereof;

e. a first controller receiving as input the position signal developed by the controlled vibration producing means sensor and generating an output signal;

f. a second controller receiving as input the transmitted vibration sensor signal and the characteristic sensor signal and generating an output signal; and

g. means for combining the output signals from the first and second controllers into a control signal for controlling the vibration producing means such that the vibration transmitted from the vibrating component to the structure through the mount is reduced.

2. The control system according to claim 1, wherein the first controller responds to the controlled vibration producing means position sensor by providing output signals which maintain a desired position of the controlled vibration producing means.

3. The control system according to claim 1, wherein the first controller produces a quasi-static, fixed, low bandwidth, broadband control signal.

4. The control system according to claim 3, wherein the first controller comprises a compensation function utilizing proportional, integral, derivative control.

5. The control system according to claim 1, wherein the second controller produces a narrow-band feedback vibration control signal.

6. The control system according to claim 5, wherein the second controller comprises

a. a frequency filter adaptive to isolate sensed vibration signals at frequencies which are multiples of the sensed characteristic plant frequency;

b. an objective function characterizing the magnitude of said isolated signals;

c. a compensation function producing a correlation between said isolated signals and said control signal for said controlled vibration producing means; and

d. an adaptive filter which generates attenuation output signals minimizing said isolated, correlated signals.

7. An active vibration control system for reducing vibration generated by a vibrating plant including a vibrating component, a structure and a hydraulic mount for mounting the vibrating component to the structure, the vibration transmitted from the vibrating component through the hydraulic mount to the structure, the control system comprising:

a. at least one hydraulic actuator for producing controlled vibrations within the mount;

b. at least one position sensor for sensing the current position of the hydraulic actuator and producing a signal representative thereof;

c. at least one vibration sensor for sensing vibrations being transmitted from the vibrating component through the hydraulic mount to the structure and producing a signal representative thereof;

d. at least one vibrating plant sensor for sensing at least one of the rotational frequencies at which said vibrating plant operates and producing a signal representative thereof;

e. a fixed, low bandwidth, near-DC, PID-based broadband control compensation feedback position controller which utilizes the position sensor signal to produce position control signals to minimize the offset between the sensed hydraulic actuator position and a predetermined hydraulic actuator position;

f. an adaptive Filtered-X LMS based narrow-band vibration controller which utilizes the vibration sensor signal to produce vibration control signals at multiple frequencies of the sensed plant characteristic frequencies; and

g. means for combining position control signals with the vibration control signals and generating an output signal, the hydraulic actuator being responsive to the output signal of the combining and output signal generating means for producing controlled vibrations in the mount for reducing vibrations transmitted through the mount from the vibrating component to the structure.

8. The control system according to claim 7, wherein the position controller comprises:

a. a scaling function;

b. a band elimination function;

c. an objective function; and

d. a compensation function.

9. The control system according to claim 8, wherein the compensation function produces the position control signal utilizing proportional, integral, derivative control compensation.

10. The control system according to claim 7, wherein the vibration controller comprises:

a. a frequency filter adaptive to isolate sensed vibration signals at frequencies which are multiples of the sensed plant characteristic frequency;

b. an objective function characterizing the magnitude of the isolated signals;

c. a compensation function producing a correlation between the isolated signals and the control signal for the controlled vibration producing means; and

d. an adaptive filter which generates attenuation output signals minimizing the isolated, correlated signals.

11. The control system according to claim 10, wherein the vibration controller further comprises:

a. a frequency downshift function which converts the vibration sensor signals to signals at baseband DC; and

b. a frequency upshift function which converts the baseband DC signals into in-band, attenuation path-based, vibration control signals.

12. The control system according to claim 11, wherein the vibration controller further comprises:

a. an input function which performs antialiasing and scaling functions on the vibration sensor signals;

b. a normalization function which normalizes the isolated signals;

c. an output function which scales the vibration control signals; and

d. a weight limiting function which evaluates the vibration control signals and transmits a freeze signal to the adaptive filter function affecting the adaptive abilities of the adaptive filter function.

13. The control system according to claim 12, wherein the frequency filter comprises:

a. a band-pass filter; and

b. a notch filter receiving as input the plant rotational frequency, the notch filter adapting its filter window based on the input plant rotational frequency.

14. An active vibration control system for reducing vibration in a rotary wing aircraft, the rotary wing aircraft including an airframe and a main rotor system having a rotor, an engine and a transmission gearbox mounted to the airframe for turning the engine force into the rotational force of a rotorshaft, the gearbox attached to the airframe with at least one hydraulic mount between the gearbox and the airframe, wherein the operation of the main rotor system generates vibration that is transferable to the airframe causing vibration on board the aircraft, the control system comprising:

a. at least one hydraulic actuator for producing controlled vibrations within the mount;

b. at least one position sensor for sensing the current position of the hydraulic actuator and producing a signal representative thereof;

c. at least one vibration sensor for sensing vibrations being transmitted from the main rotor system through the mount to the airframe and producing a signal representative thereof;

d. at least one rotational sensor for sensing the rotational frequency of the rotorshaft and producing a signal representative thereof;

e. a fixed, low bandwidth, near-DC, broadband control compensation feedback position controller which utilizes the position sensor signal to produce quasi-static position control signals to minimize the offset between the sensed hydraulic actuator position and a predetermined hydraulic actuator position;

f. an adaptive Filtered-X LMS based narrow-band vibration controller which utilizes the vibration sensor signal to produce vibration control signals; and

g. means for combining the position control signals with the vibration control signals and generating an output signal, the hydraulic actuator being responsive to the output signal of the combining and output signal generating means for producing controlled vibrations in the mount for reducing vibrations transmitted through the mount from the engine and rotor system to the airframe.

15. The control system according to claim 14, wherein the position controller comprises:

a. a scaling function;

b. a band elimination function;

c. an objective function; and

d. a compensation function.

16. The control system according to claim 15, wherein the compensation function produces the position control signal utilizing proportional, integral, derivative control compensation.

17. The control system according to claim 14, wherein said vibration controller comprises:

a. a frequency filter adaptive to isolate sensed vibration signals at frequencies which are multiples of the sensed rotorshaft frequency;

b. an objective function characterizing the magnitude of the isolated signals;

c. a compensation function producing a correlation between the isolated signals and the control signal for the; and

d. an adaptive filter which generates attenuation output signals minimizing the isolated, correlated signals.

18. The control system according to claim 17, wherein the vibration controller further comprises:

a. a frequency downshift function which converts the vibration sensor signals to signals at baseband DC; and

b. a frequency upshift function which converts the baseband DC signals into in-band, attenuation path-based, vibration control signals.

19. The control system according to claim 18, wherein said vibration controller further comprises:

a. an input function which performs antialiasing and scaling functions on the vibration sensor signals;

b. a normalization function which normalizes the isolated signals;

c. an output function which scales the vibration control signals; and

d. a weight limiting function which evaluates the vibration control signals and transmits a freeze signal to the adaptive filter function affecting the adaptive abilities of the adaptive filter function.

20. The control system according to claim 19, wherein the frequency filter comprises:

a. a band-pass filter; and

b. a notch filter receiving as input the rotorshaft rotation frequency, the notch filter adapting its filter window based on the input rotorshaft rotation frequency.