Adjustable vibration isolation and tuned mass damper systems

• US 20090294234A1
• Filed: 06/01/2009
• Published: 12/03/2009
• Est. Priority Date: 05/30/2008
• Status: Active Grant

• Current Assignee: Design, Imaging & Control, Inc.
• Original Assignee: Design, Imaging & Control, Inc.
• Inventors: Kashani, Ahmad Reza
• Granted Patent: US 8,800,736 B2
• Time in Patent Office: Days
• US Class Current: 188/379
• CPC Class Codes: F16F 15/0275 Control of stiffness

Abstract

Particular embodiments relate generally to vibration isolation systems and tuned mass dampers. In one embodiment, a vibration isolation system may include a supporting base, an isolated mass, at least one air mount, a control valve, a compressed air supply, and a supervisory controller. The air mount is positioned between the isolated mass and the supporting base. The control valve is pneumatically coupled to the air mount, the compressed air supply and the atmosphere, and is operable to adjust a flow of air to and from the air mount. The supervisory controller receives a mass relative height signal, a mass relative velocity signal, and a mass relative acceleration feedback signal corresponding to a relative acceleration of the isolated mass or a pressure of the air mount. The supervisory controller may control the control valve such that a mounting height, a damping and a stiffness level of the air mount are a function of the mass relative height signal, the mass relative velocity signal, the mass relative acceleration feedback signal, or combinations thereof.

Claims

1. A vibration isolation system comprising a supporting base, an isolated mass, at least one air mount, a control valve, a compressed air supply, and a supervisory controller, wherein:

the air mount is positioned between the isolated mass and the supporting base;

the control valve is pneumatically coupled to the air mount, the compressed air supply, and atmosphere, and is operable to adjust a flow of air to and from the air mount; and

the supervisory controller is operable to receive a mass relative height signal corresponding to a relative vertical displacement of the mass with respect to the supporting base or an air pressure of the air mount, a mass relative velocity signal corresponding to a relative velocity of the mass with respect to the supporting base, and a mass relative acceleration signal corresponding to a relative acceleration of the isolated mass with respect to the supporting base or the air pressure of the air mount, and programmed to control the control valve such that a mounting height of the air mount, a damping level of the air mount, and a stiffness level of the air mount are a function of the mass relative height signal, the mass relative velocity signal, the mass relative acceleration feedback signal, or combinations thereof.

2. A vibration isolation system as claimed in claim 1 wherein the supervisory controller is programmed to control the control valve such that:

the air mount operates at a relatively damped level when a shock excitation is present in the isolated mass or the supporting base;

the air mount operates at a relatively underdamped level when a relatively high frequency vibration is present in the mass or the supporting base;

the air mount operates at a relatively stiff level when a shock excitation is present in the mass;

the air mount operates at a relatively soft level when a relatively low frequency vibration is present in the mass; and

the air mount operates at a relatively soft level when a shock excitation is present in the supporting base, a relatively low frequency vibration is present in the supporting base, or a combination thereof.

3. A vibration isolation system as claimed in claim 2 wherein the air mount operates at a damping level and a stiffness level to isolate shock excitation when both shock excitation and vibration are present in the isolated mass, the supporting base or a combination thereof.

4. A vibration isolation system as claimed in claim 1 wherein:

the control valve is responsive to a drive signal such that a magnitude and sign of the drive signal adjusts the flow of air to and from the air mount;

the supervisory controller comprises;

a mass height feedback loop configured to generate a mass height feedback output signal by applying a mass height feedback gain G_h to the mass height error signal;

a mass velocity feedback loop configured to generate a mass velocity output signal by applying a mass velocity feedback gain G_v to the mass relative velocity signal; and

a mass acceleration feedback loop configured to generate a mass acceleration feedback output signal by applying a mass acceleration feedback gain G_a to the mass relative acceleration signal; and

the supervisory controller is operable to generate the drive signal by summing the mass height feedback output signal, the mass velocity feedback output signal, and the acceleration feedback output signal, and apply the drive signal to the control valve to adjust the mounting height of the air mount, the damping level of the air mount and the stiffness level of the air mount.

5. A vibration isolation system as claimed in claim 1 further comprising:

a displacement sensor coupled to the isolated mass or a pressure sensor coupled to the air mount configured to generate the mass relative height signal; and

a first accelerometer coupled to the isolated mass configured to generate a first acceleration signal and a second accelerometer coupled to supporting base configured to generate a second acceleration signal, wherein the mass relative acceleration signal is a difference between the first and second acceleration signals.

6. A vibration isolation system as claimed in claim 5 wherein the vibration isolation system further comprises a velocity sensor coupled to the isolated mass and configured to generate the mass relative velocity signal, or a velocity estimator coupled to the isolated mass operable to receive the mass relative acceleration signal and the mass relative height signal and provide the mass relative velocity signal at a velocity estimator output.

7. A vibration isolation system comprising a supporting base, an isolated mass, at least one main air mount, at least one main control valve, at least one stiffness air mount, at least one stiffness control valve, and a compressed air supply, wherein:

the main air mount is pneumatically coupled to the main control valve and is operable to provide a flow of air to and from the main air mount;

the stiffness air mount is pneumatically coupled to the stiffness control valve and is operable to provide a flow of air to and from the stiffness air mount;

the main air mount and the stiffness air mount are positioned between the isolated mass and the supporting base;

the stiffness air mount is operable to enter an engaged state wherein the stiffness air mount is engaged with the isolated mass, and a disengaged state wherein the stiffness air mount is disengaged from the isolated mass; and

the vibration isolation system is configured to receive an engagement signal, engage the stiffness air mount with the isolated mass in accordance with the engagement signal, vary an air pressure in the stiffness air mount in accordance with the engagement signal, and disengage the stiffness air mount in accordance with the engagement signal.

8. A vibration isolation system as claimed in claim 7 wherein the vibration isolation system is configured to disengage the stiffness air mount in accordance with the engagement signal by controlling the control valve to deflate the stiffness air mount and provide a vacuum to the stiffness air mount.

9. A vibration isolation system as claimed in claim 7 wherein the stiffness air mount is configured to mechanically pull back from the isolated mass upon deflation.

10. A vibration isolation system as claimed in claim 7 wherein the engagement signal corresponds with a motion of the isolated mass, a motion of the supporting base, or a combination thereof.

11. A vibration isolation system as claimed in claim 7 wherein:

the at least one stiffness air mount comprises a first,stiffness air mount and a second stiffness air mount;

the main air mount, the first stiffness air mount and the second stiffness air mount are configured as convoluted air springs;

the main air mount is positioned between the isolated mass and the supporting base in a main vibration direction;

the first stiffness air mount is positioned between the isolated mass and the supporting base in a first lateral direction; and

the second stiffness air mount is positioned between the isolated mass and the supporting base in a second lateral direction.

12. A vibration isolation system as claimed in claim 7 wherein the vibration isolation system comprises a main air mount and a stiffness air mount at each corner of the isolated mass.

13. A vibration isolation system as claimed in claim 7 wherein:

the main air mount is configured as a convoluted air spring and is positioned between the isolated mass and the supporting base in a main vibration direction; and

the stiffness air mount is configured as a pneumatic air spring and is positioned between the isolated mass and the supporting base in the main vibration direction.

14. A vibration isolation system as claimed in claim 13 wherein the vibration isolation system further comprises one or more additional stiffness air mounts.

15. A tuned mass damper comprising an inertia element, at least one air spring, at least one control valve, a compressed air supply, and a supervisory controller, wherein:

the control valve is pneumatically coupled to the air spring, the compressed air supply, and atmosphere, and is operable to adjust a flow of air to and from the air spring;

the inertia element is configured to be coupled to a vibrating structure such that the air spring is positioned between the inertia element and the vibrating structure;

a mass of the inertia element and a stiffness of the air spring are such that a resonant frequency of the inertia element and the air spring is substantially equal to a vibration frequency of the vibrating structure; and

the supervisory controller is operable to dynamically adjust a damping level of the air spring and a stiffness level of the air spring by applying a drive signal to the control valve.

16. A tuned mass damper as claimed in claim 15 wherein the supervisory controller is operable to tune the tuned mass damper by adjusting the stiffness level of the air spring such that the resonant frequency of the inertia element and the air spring remains substantially equal to the vibration frequency of the vibrating structure.

17. A tuned mass damper as claimed in claim 15 wherein:

the tuned mass damper further comprises a first sensor element positioned on the vibrating structure and a second sensor element positioned on the inertia element;

the first sensor element is operable to provide a first signal corresponding to an acceleration and displacement of the vibrating structure and the second sensor element is operable to provide a second signal corresponding to an acceleration and displacement of the inertia element;

the first and second signals generate a relative motion signal corresponding to a motion of a first end of the air spring with respect to a motion of a second end of the air spring; and

the supervisory controller is operable to apply the drive signal to the control valve based at least in part on the relative motion signal.

18. A tuned mass damper as claimed in claim 15 further comprising a pressure sensor operable to provide an air pressure signal to the supervisory controller, wherein:

the air pressure signal corresponds to a pressure of the air spring; and

the supervisory controller is operable to receive the air pressure signal from the pressure sensor and apply the drive signal to the control valve based at least in part on the air pressure signal.

19. A tuned mass damper as claimed in claim 15 wherein the at least one air spring comprises a plurality of air springs positioned about the inertia element between the inertia element and the vibrating structure.

20. A tuned mass damper as claimed in claim 15 wherein:

the at least one air spring comprises one or more pairs of air springs comprising a first air spring and a second air spring positioned about the inertia element;

the first air spring of each pair of air springs is positioned between a first surface of the inertia element and the vibrating structure; and

the second air spring of each pair of air springs is positioned between a second surface of the inertia element and the vibrating structure.

21. A tuned mass damper as claimed in claim 15 wherein:

the at least one air spring comprises at least one main air spring and at least one stiffness air spring;

the stiffness air spring is operable to enter an engaged state wherein the stiffness air spring is engaged with the inertia element, and a disengaged state wherein the stiffness air spring is disengaged from the inertia element; and

the supervisory controller is configured to receive an engagement signal, engage the stiffness air spring with the inertia element in accordance with the engagement signal, vary an air pressure in the stiffness air spring to semi-actively adjust a stiffness level of tuned mass damper in a lateral vibration direction and a main vibration direction in accordance with the engagement signal, and disengage the stiffness air spring in accordance with the engagement signal.