Computationally efficient means for optimal control with control constraints

• US 7,197,147 B2
• Filed: 02/27/2002
• Issued: 03/27/2007
• Est. Priority Date: 02/27/2001
• Status: Expired due to Fees

• Current Assignee: Sikorsky Aircraft Corporation (Martin Marietta Corporation)
• Original Assignee: Sikorsky Aircraft Corporation (Martin Marietta Corporation)
• Inventors: Fuller, James W., MacMartin, Douglas G., Millott, Thomas A., Goodman, Robert K.
• Primary Examiner(s): Pendleton; Brian T.
• Application Number:
  US10/083,774
• Publication Number:
  US 20030002686A1
• Time in Patent Office: 1,854 Days
• Field of Search: 381/71.1, 381/71.12, 381/71.8, 381/71.4, 244/1.N
• US Class Current: 381/71.8
• CPC Class Codes: F16F 15/00 Suppression of vibrations in systems damping of non-rotary systems using inertia effect F16F7/10; prevention or isolation of vibrations in machine tools B23Q11/0032; suppression of driveline vibrations in hybrid vehicle transmissions B60W30/20 ; vehicle seat suspension devices B60N2/50; methods or devices for protecting against, or damping of, acoustic waves, e.g. sound G10K11/16; Means or arrangements for avoiding or reducing out-of-balance forces, e.g. due to motion vibration absorbing or balancing means for aircraft propellers B64C11/008, for rotorcraft rotors B64C27/001 ; testing static and dynamic balance of machines or structures G01M1/00
• CPC Class Codes: F16F 15/02 Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems F16F15/005 takes precedence ; layered products B32B; suppression of vibration in ships B63; relieving load on bearings, using magnetic means F16C39/06
• CPC Class Codes: G05B 13/024 in which a parameter or coefficient is automatically adjusted to optimise the performance
• CPC Class Codes: G05B 5/01 electric
• CPC Class Codes: G05D 19/02 characterised by the use of electric means
• CPC Class Codes: G10K 11/17821 characterised by the analysis of the input signals only
• CPC Class Codes: G10K 11/17823 Reference signals, e.g. ambient acoustic environment
• CPC Class Codes: G10K 11/1783 handling or detecting of non-standard events or conditions, e.g. changing operating modes under specific operating conditions
• CPC Class Codes: G10K 11/17873 using a reference signal without an error signal, e.g. pure feedforward
• CPC Class Codes: G10K 2210/121 Rotating machines, e.g. engines, turbines, motors; Periodic or quasi-periodic signals in general
• CPC Class Codes: G10K 2210/1281 Aircraft, e.g. spacecraft, airplane or helicopter
• CPC Class Codes: G10K 2210/3212 Actuator details, e.g. composition or microstructure
• CPC Class Codes: G10K 2210/503 Diagnostics; Stability; Alarms; Failsafe

Abstract

A system and method reduces undesired noise or vibration in a vehicle. The ambient vibration is measured and command signals are generated over time. The command signals are generated based upon the measured vibration and based upon a control weighting. By varying the control weighting over time, the maximum possible performance is always obtained subject to the saturation constraints.

Claims

1. A method for actively controlling a physical variable of interest including the steps of:

a. measuring the physical variable;

b. generating a plurality of command signals over time, each of the plurality of command signals including at least one command signal component associated with each of a plurality of force generators wherein the plurality of command signal components are calculated based upon said physical variable measured in said step a and based upon a control weighting, the control weighting including a plurality of control weighting components, each said control weighting component associated with one of the plurality of command signal components;

c. varying the control weighting over time, including varying at least one of the plurality of control weighting components relative to another one of the plurality of control weighting components based upon a magnitude of the plurality of command signal components; and

d. activating the plurality of force generators based upon said plurality of command signals.

2. The method of claim 1 wherein said step c. further includes the step of varying more than one of said control weighting components.

3. The method of claim 2 further including the step of varying each of the control weighting components based upon a magnitude of the associated command signal component.

4. The method of claim 1 wherein said step c. further includes the step of varying each of the control weighting components based upon a magnitude of its associated command signal component.

5. The method of claim 4 wherein the plurality of control weighting components include a first control weighting component greater than a second control weighting component.

6. The method of claim 1 wherein the plurality of command signal components are calculated in said step b. by minimizing a performance index in which the control weighting components are weights on the command signal components, the performance index further including the physical variable measured in said step a.

7. A method for actively controlling a physical variable of interest including the steps of:

a. measuring the physical variable with a plurality of sensors;

b. generating a plurality of command signals over time based upon said physical variable measured in said step a and based upon a control weighting;

c. varying the control weighting over time; and

d. minimizing a performance index J=z^HW_zZ+u^HW_uu+v^HW<sub>δ

u</sub>v, where W_z, W_u and W<sub>δ

u</sub> are matrices for the control weighting on sensors z, control inputs u, and rate of change of control inputs v, respectively.

8. The method of claim 7 wherein the control weighting W_u is varied over time in said step c.

9. The method of claim 8 wherein the control weighting W_u comprises a plurality of control weighting components, each associated with one of a plurality of components of each of the plurality of command signals, the method further including the step of scaling each of the control weighting components based upon a magnitude of the associated command signals component.

10. The method of claim 7 wherein the control weighting W_z is varied over time in said step c.

25. The method of claim 8 wherein the control weighting W_u comprises a plurality of control weighting components associated with a plurality of command signal components of at least one of the plurality of command signals, the method further including the step of sealing each of the control weighting components based upon a magnitude of the associated command signal components.

11. A method for reducing sensed physical variables including the steps of:

a. generating a plurality of sensed signals based upon physical variables;

b. calculating a plurality of control commands as a function of the sensed signals;

c. comparing each of the plurality of control commands to at least one maximum;

d. reducing at least one of the plurality of control commands to a reduced control command based upon said step c.;

e. recalculating the plurality of control commands other than the reduced control command based upon the reduced control command.

12. The method of claim 11 wherein the plurality of control commands are calculated in said steps b. and e. to minimize a performance metric that includes a sensed weighting on the plurality of sensed signals and a control weighting on the plurality of control commands.

13. The method of claim 12 wherein the performance metric further includes a weighting on a change in control command over time.

14. The method of claim 12 further including the steps of:

f. computing the difference between the at least one control command and the reduced control command;

g. estimating a difference in the sensed signals based upon the difference; and

h. recalculating in said step e. based upon said difference in the sensed signals.

24. The method of claim 11 wherein said step e) is performed based upon the function and based upon the reduced control command.

15. A system for controlling a physical variable comprising:

a plurality of sensors for measuring the physical variable;

a control unit generating a plurality of command signals over time, the plurality of command signals each including a plurality of command signal components, the control unit programed to calculate the command signal components based upon the physical variable measured by the plurality of sensors and based upon a control weighting that varies over time, the control weighting including a plurality of control weighting components, each said control weighting component associated with one of the plurality of command signal components, the control unit varying the control weighting components relative to one another based upon a magnitude of at least one of the plurality of command signals; and

a plurality of force generators each activated based upon an associated one of said plurality of command signal components.

16. The system of claim 15 wherein the control unit varies selected ones of the control weighting components individually based upon a magnitude of the associated command signal components.

17. The system of claim 16 wherein the control weighting components include a first control weighting component greater than a second control weighting component.

26. The system of claim 15 wherein the control unit varies each of the control weighting components based upon a magnitude of the associated command signal components.

18. A computer readable medium storing a computer program, which when executed by a computer performs the steps of:

a. generating a first command signal based upon a measured physical variable and a control weighting, the first command signal including a plurality of command signal components, the control weighting including a plurality of control weighting components, each said control weighting component associated with one of the plurality of command signal components;

b. changing the control weighting over time after said step a. based upon a magnitude of the first command signal, including changing one of the control weighting components relative to another one of the control weighting components based upon their associated command signal components; and

c. generating a second command signal based upon the control weighting after said step b.

19. The computer readable medium of claim 18, wherein each command signal component is associated with each of a plurality of force generators, and wherein said step b. further includes the step of varying the command signal component for each of the force generators sequentially.

20. The computer readable medium of claim 19, wherein said step b. further includes the step of varying the control weighting based upon a magnitude of at least one of the command signal components.

21. The computer readable medium of claim 18, wherein said step c. further includes the step of varying each of the control weighting components based upon a magnitude of the associated command signal component.

22. The computer readable medium of claim 21 wherein the control weighting components include a first control weighting component greater than a second control weighting component.

23. A computer readable medium storing a computer program, which when executed by a computer performs the steps of:

a. generating a first command signal based upon a measured physical variable and a control weighting;

b. changing the control weighting over time after said step a.;

c. generating a second command signal based upon the control weighting after said step b, wherein the first command signal and second command signal each include at least one command signal component associated with each of a plurality of force generators, and wherein said step b. further includes the step of varying the at least one command signal component for each of the force generators sequentially.