A vibration attenuator for a rotor of an aircraft has a track housing adapted for rotation relative to the rotor and configured for rotation at a second angular velocity greater than a first angular velocity of the rotor. A track is located within the track housing and has a reaction surface, a pair of weights being configured for movement within the track and in contact with the reaction surface. A stop assembly has a pair of stops spaced 180 degrees apart, the stops separating the weights from each other, and each weight being allowed to travel within the track between the stops. A motor rotates the track housing relative to the rotor. The weights are free to travel relative to each other between a minimum-force configuration, in which the weights are positioned 180 degrees apart, and a maximum-force configuration, in which both weights are adjacent one of the stops.

An embodiment includes generating a sense signal that represents a first vibration of a platform, and reducing a level of the first vibration by generating, in response to the sense signal, a second vibration in the platform. For example, a sensor generates a sense signal representing a first vibration induced (e.g., a shock-induced vibration) in the platform. And a vibration-cancel circuit reduces or eliminates a level of the first vibration in response to the sense signal. For example, the vibration-cancel circuit reduces a magnitude of a first vibration induced in a platform, or eliminates the first vibration altogether, by generating, in the platform, a second vibration having a magnitude approximately equal to the magnitude of the first vibration and having a phase approximately opposite to the phase of the first vibration. That is, the second vibration cancels the first vibration to reduce the net vibration that the platform experiences.

A simple and robust suspension arrangement is provided for taking into account different suspension modes without the need for excessive sensoring or electronics. The novel suspension arrangement includes a first suspension element, which directly suspends the object to the frame, and a second suspension element, which suspends the object to the frame through a magnetic coupling between the object and the second suspension element. The magnetic coupling provides a magnetic coupling force (F.sub.h) to act as a threshold such that the suspension arrangement is designed to magnetically decouple the second suspen-sion element from the object when the excitation force (F.sub.e) transmitted be-tween the frame and the object exceeds the magnetic coupling force (F.sub.h).

A simple and robust suspension arrangement is provided for taking into account different suspension modes without the need for excessive sensoring or electronics. The novel suspension arrangement includes a first suspension element, which directly suspends the object to the frame, and a second suspension element, which suspends the object to the frame through a magnetic coupling between the object and the second suspension element. The magnetic coupling provides a magnetic coupling force (F.sub.h) to act as a threshold such that the suspension arrangement is designed to magnetically decouple the second suspen-sion element from the object when the excitation force (F.sub.e) transmitted be-tween the frame and the object exceeds the magnetic coupling force (F.sub.h).

A stabilization system for a rotating load, such as a flywheel, includes a mechanical bearing to continuously support a shaft of the rotating load so as to hold the shaft at a substantially fixed axis of rotation. A magnetic stabilization assembly includes a plurality of electromagnets arranged around the shaft. Control circuitry for controls a resultant magnetic field generated by the electromagnets such that the magnetic field acts on a ferromagnetic element of the shaft to reduce imbalance forces acting on the shaft.

A stabilization system for a rotating load, such as a flywheel, includes a mechanical bearing to continuously support a shaft of the rotating load so as to hold the shaft at a substantially fixed axis of rotation. A magnetic stabilization assembly includes a plurality of electromagnets arranged around the shaft. Control circuitry for controls a resultant magnetic field generated by the electromagnets such that the magnetic field acts on a ferromagnetic element of the shaft to reduce imbalance forces acting on the shaft.

Systems and methods are provided for active vibration damping. One embodiment is a method for damping vibration in a mechanical system. The method includes detecting a vibration at a coupling of the mechanical system, generating a countervibration based on the detected vibration, and operating the mechanical system while generating the countervibration.

Systems and methods are provided for active vibration damping. One embodiment is a method for damping vibration in a mechanical system. The method includes detecting a vibration at a coupling of the mechanical system, generating a countervibration based on the detected vibration, and operating the mechanical system while generating the countervibration.

A controllable magneto-rheological device includes an annular cylinder formed by inner and outer walls connected at first and second opposing ends and forming an inner shaft configured to receive an operational component of an engine, generator or other device including one or more rotating structures. A magneto-rheological fluid is provided to fill a volume between the inner and outer walls of the annular cylinder. A plurality of electro-magnetic coils are positioned around the outer wall of the annular cylinder. One or more current controllers are coupled to the plurality of electro-magnetic coils for introducing a current through each of the electro-magnetic coils and corresponding magnetic flux through the magneto-rheological fluid. A level of current provided to each of the plurality of electro-magnetic coils directly affects the viscosity of the magneto-rheological fluid and thus the stiffness and damping levels of the controllable magneto-rheological device.

A bolt catcher and extractor for use with a separation nut and an attaching preloaded bolt that secure a payload to a launch vehicle or spacecraft. The bolt catcher extracts the attaching bolt from the separation nut, pulls it clear of the interface between the launch vehicle or spacecraft and the released payload, and captures it within the bolt catcher housing. The released bolt may have kinetic energy due to the strain energy stored by the pre-release bolt preload. The bolt catcher may have a magnetic eddy current damper that controls the bolt velocity during bolt extraction and dissipates the bolt kinetic energy as heat. The bolt may be magnetically non-impact captured within the bolt catcher. Bolt momentum at the end of the bolt extraction is less than 2% of that of bolt catchers of the prior art. Shock to the released payload or deployable equipment is near zero.