Self tuning motion/vibration suppression system

• US 5,333,819 A
• Filed: 03/12/1993
• Issued: 08/02/1994
• Est. Priority Date: 03/12/1993
• Status: Expired due to Term

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: General Electric Company
• Inventors: Stetson, John B. Jr.
• Primary Examiner(s): Barefoot, Galen L.
• Application Number:
  US08/031,252
• Time in Patent Office: 508 Days
• Field of Search: 244/17, 244/27, 244/164, 244/165, 244/176, 244/170, 310/13, 310/15, 310/111, 310/51, 318/128, 318/135, 381/71, 248/550, 248/559, 188/378, 367/1, 367/191, 367/508, 367/509, 364/463, 364/459
• US Class Current: 244/164
• CPC Class Codes: B64G 1/244 Spacecraft control systems
• CPC Class Codes: B64G 1/285 using momentum wheels
• CPC Class Codes: B64G 1/36 using sensors, e.g. sun-sensors, horizon sensors
• CPC Class Codes: B64G 1/38 damping of oscillations, e.g. nutation dampers
• CPC Class Codes: F16F 7/1005 characterised by active control of the mass
• CPC Class Codes: G05D 19/02 characterised by the use of electric means
• CPC Class Codes: G10K 2210/1281 Aircraft, e.g. spacecraft, airplane or helicopter
• CPC Class Codes: G10K 2210/1291 Anti-Vibration-Control, e.g. reducing vibrations in panels or beams
• CPC Class Codes: G10K 2210/3211 Active mounts for vibrating structures with means to actively suppress the vibration, e.g. for vehicles
• CPC Class Codes: G10K 2210/3217 Collocated sensor and cancelling actuator, e.g. "virtual earth" designs
• CPC Class Codes: G10K 2210/501 Acceleration, e.g. for accelerometers

Abstract

A vibration suppression system senses undesired mechanical motion of a body, and continuously drives a proof mass actuator system to reduce disturbances. An inertial or relative displacement sensor is processed to determine the energy content of the motion, and a correction signal is generated which is summed with the actuator drive signal to minimize the sensed motion energy. The position of the proof mass is sensed, and processed by differentiating and scaling, and the processed proof mass position signal is also summed with the actuator drive signal. The system causes the proof mass actuator loop natural frequency to tend to track the frequency associated with the maximum vibrational energy.

Claims

1. A compensation system for imparting mechanical motion to a proof mass coupled to a moving mass, comprising:

a first body;

a second body elastically coupled to said first body;

a source of energy coupled to at least one of said first and second bodies for causing relative mechanical motion between said first and second bodies;

a proof mass;

actuating means coupled to said proof mass and to one of said bodies for causing motion of said proof mass relative to said one of said bodies in response to an actuator drive signal;

motion sensing means coupled to at least one of said first and second bodies for generating a motion signal representative of undesired mechanical motion and including at least a rate component of said motion;

motion energy determination means coupled to said motion sensing means, and to said compensation means for squaring said rate component of said motion signal to produce a motion energy signal representative of the energy contained in said motion, for integrating said motion energy signal to produce a integrated energy signal representative of the time window average of the total motion energy, and for generating a compensation correction factor which tends to minimize said integrated energy signal; and

compensation and amplification means coupled to said motion energy determination means and to said actuating means, for generating said actuating signal, and for using the said compensation correction factor to continuously change the magnitude of said actuator drive signal in a manner which tends to maintain said integrated energy signal near said minimum.

2. A system according to claim 1 in which said motion sensing means is inertial, and is coupled to one of first and second bodies.

3. A system according to claim 1 in which said motion sensing means is a relative motion sensor coupled to both first and second bodies.

4. A method for compensating for undesired mechanical motion of a moving mass by actuating a proof mass coupled to said moving mass, comprising the steps of;

sensing the motion of a body to generate a motion-representative signal;

differentiating said motion-representative signal to produce a rate-representative signal;

squaring said rate representative signal to produce a current-energy-related signal;

summing a plurality of successive ones of said current-energy-related signals to produce a time integrated signal representative of the motion energy within a time window;

generating a correction signal in response to said integrated signal;

squaring said correction signal to produce a squared correction signal;

sensing the position of a proof mass associated with an actuator coupled to said body to produce a proof mass position signal;

scaling said proof mass position signal to produce a scaled proof mass position signal;

differentiating said proof mass position signal to produce a differentiated proof mass position signal;

summing said squared correction signal, said scaled proof mass position signal and said differentiated proof mass position signal with a signal related to said rate-representative signal to produce an actuator drive signal for driving said proof mass.

5. A method according to claim 4, wherein said step of generating a correction signal comprises the further steps of;

comparing the current value of said integrated signal with a stored minimum value of said integrated signal, setting the current value of said stored minimum value of said integrated signal equal to said integrated signal when the current value of said stored minimum value of said integrated signal is greater than said current value of said integrated signal, and inverting the sign of an increment signal when the current value of said stored minimum value of said integrated signal is less than said current value of said integrated signal; and

setting the current value of the correction signal equal to the sum of the previous value of said correction signal and the current increment signal.