Computationally efficient means for optimal control with control constraints

• US 20020120366A1
• Filed: 02/26/2002
• Published: 08/29/2002
• Est. Priority Date: 02/27/2001
• Status: Active Grant

• Current Assignee: Sikorsky Aircraft Corporation (Martin Marietta Corporation)
• Original Assignee: Sikorsky Aircraft Corporation (Martin Marietta Corporation)
• Inventors: Goodman, Robert Karl
• Granted Patent: US 7,107,127 B2
• Time in Patent Office: Days
• US Class Current: 700/280
• 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 method and system that reduces undesired vibration in a vehicle measures ambient vibration and generates a first command signal based upon said vibration measured in said step a. If a first component of the first command signal exceeds a maximum allowable, the first component of the first command signal must be constrained. A residual vibration resulting from the constraint of the first component is then calculated. A second command signal to compensate for said residual vibration is then calculated. Force generators are then activated based upon the constrained first component and the second command signal in order to reduce the vibration.

Claims

1. A method for reducing sensed physical variables comprising:

a) sensing a plurality of physical variables;

b) generating a first sensed signal as a function of the sensed physical variables;

c) generating a first control command signal as a function of the first sensed signal;

d) constraining a k_th component of the first control command signal;

e) calculating a residual resulting from the application of the constrained k_th component;

f) generating a second control command signal in response to the residual; and

g) generating a compensating force as a function of the constrained k_th component and the second control command signal.

2. The method according to claim 1, wherein said step d) further includes the steps of:

comparing components, including the k_th component, to a maximum threshold; and

scaling the k_th component by a constant based upon the k_th component exceeding the maximum threshold.

3. The method according to claim 2 further including the steps of:

generating the constrained k_th component (u_i,k)_new in said step d), where (u_1,k)_new=Cu_i,k and C=|(u_i)_k|/U_max, and U_max is the maximum threshold;

calculating a change in the k_th component in the control command signals as a function of Δ

u_i,k=(ui_,k,)_new−

u<sub>i−

1,k</sub>; and

calculating the residual as a function of;

(z<sub>i−

1</sub>)_new=(z<sub>i−

1</sub>)+T Δ

u_1,k.

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

generating a controller weighting matrix;

generating a constrained control component (W_{u,new k,k}) as a function of;

W_{u,new k,k}=W_{u k,k}+A,

 

where A is a constant that greatly exceeds the magnitude of W_{u k,k}.

5. The method according to claim 4, further comprising:

calculating a new command change (Δ

u_1,new) as a function of

Δ

u_i,new=D_new(W_u,new u<sub>i−

1</sub>+T^TW_z(Z<sub>i−

1</sub>)_new) and where;

D_new=−

(T^T W_zT+W_u,new+W<sub>Δ

u</sub>)<sup>−

1</sup>

6. A method for actively controlling vibration including the steps of:

a. measuring ambient vibration;

b. generating a first command signal based upon said vibration measured in said step a;

c. constraining a first component of the first command signal;

d. determining a residual vibration resulting from the constraint of the first component;

e. generating a second command signal based upon said residual vibration.

7. The method of claim 6 further including the steps of:

f. activating a plurality of force generators based upon said constrained first component and said second command signal.

8. The method of claim 7 wherein said step c. further includes the step of comparing said first component of the first command signal to a maximum allowable command signal.

9. The method of claim 8 wherein said step c. further includes the step of reducing the first component to the maximum allowable command signal.

10. An active control system comprising:

A plurality of sensors for measuring ambient vibration;

A control unit generating a first command signal based upon said vibration measured by said plurality of sensors, constraining a first component of the first command signal, determining a residual vibration resulting from the constraint of the first component and generating a second command signal based upon said residual vibration;

A plurality of force generators activated based upon said first command signal, said second command signal and said constrained first component.

11. The active control system of claim 10 wherein the control unit compares said first component of said first command signal to a maximum allowable command signal.

12. The active control system of claim 12 wherein the control unit reduces the first component to not exceed the maximum allowable command signal.

14. The computer readable medium of claim 13 which when executed by a computer further performs the steps of:

e. activating a plurality of force generators based upon said first command signal, said constrained first component and said second command signal.

15. The computer readable medium of claim 13 which when executed by a computer said step b. further includes the step of comparing said first component of the first command signal to a maximum allowable command signal.

16. The computer readable medium of claim 15 wherein said step c. further includes the step of reducing the first component to the maximum allowable command signal.

13. 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 measured vibration;

b. constraining a first component of the first command signal;

c. determining a residual vibration resulting from the constraint of the first component;

d. generating a second command signal based upon said residual vibration.