System and method for vibration control in a rotorcraft using an adaptive reference model algorithm

• US 9,027,873 B2
• Filed: 03/01/2010
• Issued: 05/12/2015
• Est. Priority Date: 02/27/2009
• Status: Active Grant

• Current Assignee: Textron Innovations Incorporated (Textron Inc)
• Original Assignee: Textron Innovations Incorporated (Textron Inc)
• Inventors: Heverly, David E. II, Singh, Rupinder, Pappas, John
• Primary Examiner(s): O'Hara, Brian M
• Application Number:
  US13/202,731
• Publication Number:
  US 20110303784A1
• Time in Patent Office: 1,898 Days
• Field of Search: 244/17.13
• US Class Current: 244/17.13
• CPC Class Codes: B64C 2027/004 using actuators, e.g. active systems
• CPC Class Codes: B64C 27/001 Vibration damping devices
• CPC Class Codes: F16F 15/002 characterised by the control method or circuitry control of mechanical oscillations per se G05D19/00
• CPC Class Codes: G10K 11/17817 between the output signals and the error signals, i.e. secondary path
• CPC Class Codes: G10K 11/17823 Reference signals, e.g. ambient acoustic environment
• CPC Class Codes: G10K 11/17854 the filter being an adaptive filter
• CPC Class Codes: G10K 11/17857 Geometric disposition, e.g. placement of microphones
• CPC Class Codes: G10K 11/17879 using both a reference signal and an error signal
• CPC Class Codes: G10K 11/17883 the reference signal being derived from a machine operating condition, e.g. engine RPM or vehicle speed
• CPC Class Codes: G10K 2210/1281 Aircraft, e.g. spacecraft, airplane or helicopter
• CPC Class Codes: G10K 2210/3012 Algorithms
• CPC Class Codes: G10K 2210/3055 Transfer function of the acoustic system
• CPC Class Codes: G10K 2210/3056 Variable gain

Abstract

The adaptive reference model algorithm uses a gain scheduling feature combined with a customized Least-Squares routine as an adaptive method for adjusting feedback control so as to account for variations in Transfer Function (G), thereby optimizing the effectiveness of the Active Vibration Control (AVC) System. The Least-Squares routine identifies the transfer function in a background process without interruption of closed loop vibration control. This identification approach is accomplished without intentional interrogation of the AVC actuators and without intentional vibration level changes. For this adaptive control logic, the dynamic relationship between AVC actuators and AVC sensors is represented by a mathematical model of Transfer Function (G). The mathematical model of Transfer Function (G) is continuously updated by the Least-Squares routine. A feedback gain (H) is computed from the mathematical model of Transfer Function (G), and the feedback gain (H) is updated each time the mathematical model of Transfer Function (G) is updated.

Claims

1. A method for controlling vibration in a rotorcraft, comprising:

measuring a fuselage vibration in the rotorcraft with a sensor, the fuselage vibration originating from a propulsion system of the rotorcraft;

determining an actuator command signal with an adaptive reference model algorithm, wherein the determining of the actuator command signal with the adaptive reference model algorithm comprises one or more iterations of;

continuously identifying a transfer function reference model with a least-squares routine, the transfer function reference model representing a predicted relationship between the sensor and the vibration control actuator;

computing a feedback control gain from the transfer function reference model in a closed loop; and

updating the feedback control gain each time a true transfer function is newly identified;

wherein the continuously identifying of the transfer function reference model with the least-squares routine occurs in a background process without interruption of the determining of the actuator command signal; and

commanding a vibration control actuator with the actuator command signal so as to impart a cancelling vibration in a manner that at least partially cancels the vibrations originating from the propulsion system;

wherein the closed loop includes a gain schedule database, the gain schedule database being available for providing data to the transfer function reference model during times of rapid transfer function changes, and

wherein the least squares routine is configured to identify the transfer function reference model during times of slow changes to the true transfer function without needing information from the gain schedule database.

2. The method according to claim 1, wherein the transfer function reference model is a mathematical matrix.

3. The method according to claim 1, wherein the continuously identifying of the transfer function reference model with the least-squares routine is accomplished without interrogating the vibration control actuator.

4. The method according to claim 1, wherein the determining of the actuator command signal with the adaptive reference model algorithm further comprises:

minimizing an error function with the least-squares routine, the error function being a difference between a change in the fuselage vibration measured with the sensor and a change in a predicted vibration response computed with the transfer function reference model;

wherein the minimizing the error function causes the transfer function reference model to resemble the true transfer function, thereby optimizing vibration attenuation in the rotorcraft; and

wherein the true transfer function represents an actual dynamic relationship between the sensor and the vibration control actuator.

5. The method according to claim 4, wherein the change in the predicted vibration response is computed only if the actuator command signal is changed.

6. The method according to claim 1, further comprising:

measuring a rotorcraft parameter for controlling rotorcraft vibration and the transfer function reference model, the parameter including at least one of;

rotorcraft gross weight, rotorcraft fuel quantity, rotorcraft air-speed, and rotorcraft altitude; and

supplying the measured rotorcraft parameter changes to a feedback control logic in the closed loop portion of the adaptive reference model algorithm.

7. The method according to claim 1, further comprising:

measuring a rotor revolutions per minute (RPM); and

supplying a measured rotorcraft parameter to a feedback control logic in the closed loop.

8. The method according to claim 1, wherein the gain schedule database is automatically populated and updated throughout a lifetime of the rotorcraft.

9. The method according to claim 1, wherein the continuously identifying of the transfer function reference model with the least-squares routine is accomplished during closed loop vibration control without interrogating the vibration control actuator.

10. The method according to claim 1, wherein the determining of the actuator command signal with the adaptive reference model algorithm further comprises:

minimizing an error function with the least-squares routine, the error function being a difference between a change in the fuselage vibration measured with the sensor and a change in a predicted vibration response computed with the transfer function reference model;

wherein a known change in the actuator command signal contributes to the change in the fuselage vibration;

wherein the minimizing of the error function causes the transfer function reference model to resemble the true transfer function, thereby optimizing vibration attenuation in the rotorcraft; and

wherein the true transfer function represents an actual dynamic relationship between the sensor and the vibration control actuator.