Abstract: A controlled equilibrium device comprising a housing; at least one spring, each at least one spring having a spring stiffness; and a load leveling device movable through the housing between a first maximum displacement position and a second maximum displacement position, the load leveling device comprising a deadband displacement zone defined between a first deadband displacement threshold and a second deadband displacement threshold, the displacement required to reach the first and second deadband displacement thresholds being less than the displacement distances required to reach the first and second maximum displacement positions, the at least one spring stiffness being substantially constant when the displacement of the load leveling device is within the deadband zone, the stiffness of the at least one spring being modified to a second stiffness when the load leveling device is equal to or beyond either the first deadband displacement threshold or the second deadband displacement threshold.

Abstract: An Adaptive Off-state (AO) control method (55) for use in conjunction with a suspension system (10) including a controllable damper (22) interconnecting relatively moveable members (12, 14) to reduce the transmission of vibrational forces therebetween. Such suspension systems (10) are switchable between alternative on- and an off-state in accordance with a primary control method (53) and/or a secondary override control method (59). Sensors (48, 52) monitor the parameters of the suspension system (10), such as the displacement, velocity, and acceleration of the moveable members (12, 14). Damper command signals (107) are provided to the damper (22) in the on-state (116) to adjust the damping characteristics thereof. In the off-state, the damping signal in conventional systems is approximately zero or a constant relatively low magnitude.

Abstract: An isolation system includes a housing that contains an electromagnet, a sensor and a controller. The housing is mounted underneath a table top of an isolation table (or other structure requiring isolation from a second body), and target elements, such as permanent magnets, are associated with the frame of the table in proximity to the housing. The sensor provides an input signal representative of motion of the table to the controller, which generates a control signal for the electromagnet to produce a force acting on the target element. The housing can be attached to the table top with magnets, which facilitate installation. The housing provides a unit that is simple to install, is unobtrusive, and advantageous for retrofitting existing isolation tables.

Abstract: A controllable valve assembly (18) applicable in Magnetorheological (MR) fluid devices (20), such as MR mounts and MR dampers. The valve assembly (18) includes a valve body (32) having a magnetic circuit (40) contained therein which carries magnetic flux .phi., a controllable passageway (42) within the magnetic circuit (40), a MR (magnetically controlled) fluid (44) including soft-magnetic particles in a liquid carrier contained in the controllable passageway (42), a magnetic flux generator, such as a wound wire coil (46), generating magnetic flux .phi. which is directed through the MR fluid (44) in the controllable passageway (42) thereby generating "rheology" changes causing restriction in flow of MR fluid (44) therethrough.

Abstract: A controllable valve assembly (18) applicable in Magnetorheological (MR) fluid devices (20), such as MR mounts and MR dampers. The valve assembly (18) includes a valve body (32) having a magnetic circuit (40) contained therein which carries magnetic flux .PHI., a controllable passageway (42) within the magnetic circuit (40), a MR (magnetically controlled) fluid (44) including soft-magnetic particles in a liquid carrier contained in the controllable passageway (42), a magnetic flux generator, such as a wound wire coil (46), generating magnetic flux .PHI. which is directed through the MR fluid (44) in the controllable passageway (42) thereby generating "rheology" changes causing restriction in flow of MR fluid (44) therethrough.

Abstract: An Active Vibration Absorber assembly (20) including a casing (24), a first tuning mass (32) supported relative to the casing (24) which is actively vibratable by a force generator (40) in a first direction (along an A--A axis), a second tuning mass (32') supported relative to said casing (24) which is actively vibratable by a force generator (40') in a second direction (along axis B--B) generally orthogonal to the first direction, and a flexible member (26) flexibly supporting the casing (24). In a first embodiment, the tuning masses (32, 32') are vibratable by a magnet and coil assembly within shakers (25, 25') and the flexible member (26) is a beam. In other embodiments, multiple beams are employed to restrict the vibration of casing (24) to substantially planar motion. The AVA assembly (20) finds application in Active Structural Control (ASC) systems for actively canceling vibration or noise in vehicle cabins (example: automobiles, aircraft).

Abstract: An Active Structural Control (ASC) system (10) and method which includes a plurality of Active Vibration Absorbers (AVAs) (40) attached to a yoke (32) included within a pylon structure (28) preferably comprising a spar (38) and a yoke (32) which is located intermediate between an aircraft fuselage (20) and an aircraft engine (18) for controlling acoustic noise and/or vibration generated within the aircraft's cabin (44) due to unbalances in the aircraft engine (18). The ASC system (10) includes a plurality of error sensors (42) for providing error signals, and at least one reference sensor (49 or 50) for providing reference signals indicative of the N1 and/or N2 engine rotations and/or vibrations, and a preferably digital electronic controller (46) for processing the error and reference signal information to provide output signals to drive the plurality of AVAs (40) attached to the yoke (32).

Abstract: An active fluid mounting for isolating vibration between a vibrating member (21) and a structure (23). In one aspect, the active fluid mounting (20) includes an inner member (22), an outer member (24), a first flexible element (26), and an cartridge-like active fluid element (28) which is unitary and readily detachable, attached between the inner and outer members, (22) and (24).

Abstract: A fluid-filled Active Vibration Absorber (AVA) (20) is described for attaching to, and controlling dynamic vibration of the member (22). The AVA (20) is comprised of primary tuning mass (23) preferably including an additional inertial tuning mass (26) which is associated with a primary resonant frequency (fn1), a flexible element (28) for interconnecting the primary mass (23) and, thus, interconnecting inertial tuning mass (26) to member (22), at least one, and preferably two, fluid chambers, (30) and (32), each having a defined volume stiffness Kv'1, Kv'2, a fluid (34) contained within the at least one and preferably two, fluid chambers, (30) and (32), a moveable piston (36) dynamically interacting with the fluid (34) in the at least one fluid chamber and preferably, in first and second fluid chambers, (30) and (32), to cause pressure variations which dynamically drive the primary tuning mass (23) within a range about the primary resonant frequency (fn1).

Abstract: A flexibly-mounted active vibration absorber (AVA) which has a secondary controllable mass M.sub.3. If the passive resonance of mass M.sub.2 of the tuned absorber is insufficient to control the input vibration, a secondary mass M.sub.3 is vibrated at a frequency, amplitude and phase sufficient to make up the deficiency in mass M.sub.2. Many embodiments are described which depict variations on the first spring used for flexibly mounting the AVA, the actuators used to drive the AVA, and the attachment features for attaching to a vibrating member. Further in another aspect, means for counterbalancing the moments produced by the AVA are described.

Abstract: A system (20) which includes a frequency-dependent decoupler (21) arranged in a series-spring relationship with an actuator (26) for supplying active forces to cancel vibration. The system (20) also includes a spring (28) for providing a primary load path. The system (20) is responsive to at least one sensor (32, 34, 36 or 38) and is controlled via controller (30). The decoupler (26) has greater frequency dependency than the spring (28) and allows the actuator (26) to be effectively decoupled at low frequency, yet coupled at high frequency. This frequency dependent coupling allows the system (20)to accommodate transient static and low frequency loads and motions by allowing motion across the decoupler (21). However, at high frequency, the decoupler (21) becomes stiffer and couples the actuator (26) with the moving members (22) and (24) such that motion across the decoupler (26) is minimized and the actuator (26) becomes more effective at high frequency attenuation.

Abstract: A non-active regenerative system (20) which regenerates energy by taking energy from relative motion of members (22) and (24) and using it later to accomplish overall improved performance and eliminates the need for an active source to provide assisting forces. The non-active regenerative system (20) includes an energy transformer element (26) interconnecting a first member (22) and second member (24) which converts relative motion to an energy in storable form, and an energy management element (30) which channels the flow of energy to and from an energy storage element (32) to produce assisting forces. The energy management element (30)is commanded by a controller (36) which is responsive sensors (34a, 34b, 34c, and 34d) which provide signals indicative of the system condition. Power is supplied to the energy management (30), sensors (34a, 34b, 34c, and 34d), and controller (36), only if required, by power source (40). However, no active power source is needed to drive the transformer element (26).

Abstract: An active mount for fixed wing applications. One aspect of the invention provides decoupling of two tones which are close in frequency by positioning the mount actuators and error sensors in the primary transmission path of the disturbance vibration and by providing adequate spatial separation between the two sets of error sensors to reduce or eliminate cross-coupling of the signals. Another aspect of the invention utilizes orthogonally positioned actuators with corresponding actuators of paired mounts being focalized for each engine.

Abstract: A method and apparatus for reducing suspension end-stop collisions is disclosed. The method and apparatus controls the operation of an isolation system having an adjustable damper assembly interconnecting relatively movable members to attenuate the transmission of forces therebetween, in which relative movement of the members is restricted beyond a certain limit by one or more end stops. Sensors monitor the conditions of the system such as the displacement, velocity and acceleration of the members. Damper command signals are provided to the damper assembly to adjust the damping characteristics of the assembly, as determined by the data, in accordance with both a primary control policy and an override control policy. The override control policy alters the damper command signals as necessary to increase the damping characteristics of the damper assembly at times when the isolation system is likely to meet or exceed the end stops in order to minimize the incidence of end-stop collisions.

Abstract: An improved method and means for control and accomplishment of semi-damper assembly transition between high damping and low damping states is provided which takes advantage of the available inherent dynamic fluid pressure forces produced by the condition of motion between supported and supporting members. Deferral or delay of damper state transitions to avoid force discontinuities or system noise is accomplished mechanically, or automatically internal to the structure of the adjustable valve assembly. A voice coil actuated valve slider is operable within the piston of the damper assembly to modulate the damping coefficient in conjunction with check valves. The delay of damper state transition from high to low damping is accomplished independent of the particular control policy utilized until the fluid pressure differential across the valve slide is a preselected low value. Commanded valve switching and motion condition sensing requirements are also minimized by the reversible check valves.

Abstract: The bidirectional valve assembly provides for selection of retraction and extension damping characteristics which can accommodate relatively large separation of damping curves. Two cooperable valve discs or ring members are provided which function in unison to resist fluid flow in a first fluid flow direction, while a single one of the valve ring members functions primarily to resist fluid flow in the other direction. In a first embodiment, one of the two cooperable valve ring members comprises a compliant retainer or fulcrum against which the other valve ring member moves in unison therewith to produce relatively low damping in retraction. The other valve ring member moves alone in extension to produce relatively high damping. In an alternative embodiment, the two cooperable valve ring members are superimposed and move in unison during extension, as dictated by their combined stiffness.

Abstract: An improved method and means for control and accomplishment of semi-active damper means transition between high damping and low damping states is provided which takes advantage of the available inherent dynamic fluid pressure forces produced by the condition of motion between supported and supporting members. Deferral or delay of damper state transitions to avoid force discontinuities or system noise is accomplished mechanically, or automatically internal to the structure of the adjustable valve means. The delay of damper state transition from high to low and low to high damping is accomplished independent of the particular control policy utilized until the fluid pressure differential across the valve ring members is a preselected low value. Commanded valve switching and motion condition sensing requirements are also minimized by reversible check valve means.

Abstract: Operation of a continuously variable semiactive damper of the system is modified so as to reduce generation in the system of undesirable shocks and noise. The modifications include delaying some or all of the changes in the on/off states of the damper, and/or limiting the rate and/or extent of changes in the damping coefficient of the damper at certain of the times when the damper is in an on state.