Abstract: Vibration control systems, devices, and methods are provided for a rotary wing aircraft having a rotor including a plurality of blades (20) each attached to a hub (10) at its root end and capable of pitching with respect to the hub (10). The systems, devices, and methods include a blade pitch adjuster (100) that is passively adjustable in response to aerodynamic loading on the plurality of blades (20) to adjust a pitch of one of the plurality of blades (20) with respect to the hub (10) based on a frequency of the aerodynamic loading. The blade pitch adjusters (100) can be configured to exhibit relatively high stiffness at the rotor rotating frequency and tailored dynamics at frequencies higher than the rotor rotating frequency such that hub loads at one or more higher harmonics are reduced.

Abstract: The land vehicle includes a body, a power plant and a plurality of land engagers, the land engagers for engaging land and propelling the land vehicle across land. The land vehicle includes a controllable suspension system, the controllable suspension system for controlling suspension movements between the body and the land engagers. The land vehicle includes a computer system and suspension sensors located proximate the land engagers for measuring suspension parameters representative of suspension movements between the body and the land engagers and outputting a plurality of suspension sensor measurement outputs. The land vehicle includes controllable force suspension members located proximate the land engagers and the suspension sensors, the controllable force suspension members applying suspension travel forces between the body and the land engagers to control the suspension movements.

Abstract: Helicopter reduced vibration axial support struts and aircraft suspension system are disclosed with at least one vibration controlling fluid containing strut. The powered struts include an outer rigid housing containing an inner rigid member and first and second variable volume fluid chambers. Fluid pressure differentials are created between the first and second variable volume fluid chambers to control motion between the strut ends. The powered fluid containing struts, support isolators, suspension systems, and methods of operation provide reduced helicopter aircraft vibrations.

Abstract: The land vehicle includes a body, a power plant and a plurality of land engagers, the land engagers for engaging land and propelling the land vehicle across land. The land vehicle includes a controllable suspension system, the controllable suspension system for controlling suspension movements between the body and the land engagers. The land vehicle includes a computer system and suspension sensors located proximate the land engagers for measuring suspension parameters representative of suspension movements between the body and the land engagers and outputting a plurality of suspension sensor measurement outputs. The land vehicle includes controllable force suspension members located proximate the land engagers and the suspension sensors, the controllable force suspension members applying suspension travel forces between the body and the land engagers to control the suspension movements.

Abstract: Helicopter reduced vibration axial support struts and aircraft suspension system are disclosed with at least one vibration controlling fluid containing strut. The powered struts include an outer rigid housing containing an inner rigid member and first and second variable volume fluid chambers. Fluid pressure differentials are created between the first and second variable volume fluid chambers to control motion between the strut ends. The powered fluid containing struts, support isolators, suspension systems, and methods of operation provide reduced helicopter aircraft vibrations.

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: 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: A vibration control apparatus (20) and method for a calender (18) for controlling vibration between two or more rolls (ex. 22, 24) which controls vibration induced thickness variations in a medium (27) exiting from the nip. The apparatus (20) includes a frame (19), a first and second rolls (22, 24) mounted relative to the frame (19), and a force generator (32), such as an electromechanical active actuator, servo-hydraulic actuator, controllable semi-active damper, Active Vibration Absorber (AVA), or Adaptive Tuned Vibration Absorber (ATVA), provides cancelling forces to control vibration between the first and second roll (22, 24) thereby, controlling such vibration induced thickness variations in the medium (27). Preferably, the apparatus (20) includes at least one sensor (ex.

Abstract: A hybrid active-passive system (20) for reducing noise within a passenger compartment and vibration of a fuselage of a vehicle, such as an aircraft (turboprop, turbofan, or helicopter). The hybrid active-passive system (20) includes, in combination: an active acoustic producer such as a loudspeaker (35), Active Vibration Absorber (AVA) (34), or active absorber assembly (39) for producing antinoise within the compartment (42), and a passive resonant device, such as a passive Tuned Vibration Absorber (TVA) (36), or passive TVA assembly (37) for controlling vibration of the fuselage or structural supports interconnecting the disturbance source (e.g. power plants (26), propellers (28a), gearbox (57), main rotor (28m), tail rotor (28t)) and the fuselage wall (25).

Abstract: An active control method and apparatus for controlling vibration or sound wherein the computational burden to adaptively update the control filter within the update model is reduced. The apparatus includes means for producing an input signal for input to the update model and the reduction block, means for generating an error sensor, and an output device for canceling sound and/or vibration at a selected location. The method uses a gradient descent algorithm such as the filtered-x LMS algorithm and replaces the long filter model with a shortened length filter model. Error signal information together with the output information from the shortened length filter model are used to update the coefficients of the control filter according to an update calculation method. The shortened filter model only contains frequency response information at the L frequencies of interest.

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: An active isolator with a closed-loop feedback control system which uses an actuator in parallel spring relation to a static load spring to control the dynamic vibration transmitted from a vibrating device over a broad band frequency range. A collocated sensor is installed to sense the vibration of the isolated element and is amplified and fed, filtered and amplified again, reversed in sign and fed directly into the actuator. No external synchronizing signal or processor is needed. This simple active control is practical only where the combined series dynamic stiffness of the structure and vibrating body is much less than or much greater than the active mount's dynamic stiffness.

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: The system includes at least one semiactive damper whose switching between high damping and low damping states is at times delayed until the relative velocity across the damper is no greater than a preselected low magnitude, or until the energy stored by a resilient deformable system member is no greater than a predetermined magnitude, or until the first to occur of either of the foregoing events.

Abstract: An improved isolation system for time responsive attenuation control led electromechanical valve assembly comprising the piston of motion between spaced members is provided having a remotely actuator of a fluid damper for generating motion attenuating forces. The piston valve assembly employs a moving coil valve slider moveable between first and second positions to generate damper forces independently of the fluid pressure differential between opposing fluid chambers. Direct flow passages extend through the piston valve assembly between the opposing chambers. In the first position of the valve slider, fluid flow is substantially permitted through the direct flow passages to provide a substantially nonresistant damper force. In the second position, the valve slider intersects internal porting portions of the direct flow passages to substantially restrict fluid flow therethrough and provide a resistant damper force.

Abstract: The fluid circuitry connecting variable volume chambers of the semiactive damper includes valve assemblies which collectively effect mechanical implementation of a preselected damper control policy that is based in part upon changes in the sign of the absolute velocity of a supported member of the system of which the damper forms a part. One of the valve assemblies has an inertial body which is connected to a movable system member but which remains substantially stationary during system operation. The inertial body and a valve member of the assembly are interconnected by a linkage which in one embodiment includes a frictional type connector, and which in another embodiment includes a dashpot.

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.

Abstract: The apparatus is particularly suited for control of the performance of a vehicle suspension system or similar plant having controllable semiactive dampers capable of either high or low damping modes. Different plant modes ensue from different combinations of the damper modes. The control apparatus includes observer devices that model each of the plant modes and produce estimates of the plant output or performance that would be produced in each plant mode. A cost function device identifies the optimal one of the estimates, and the dampers in the real plant are adjusted so as to cause the plant to assume the one of its modes modeled by the observer producing the optimal estimate. In an alternative reduced form of the invention, the functions of the observer and cost function devices are performed by switching function generators that produce switching functions indicative of the estimated worth of the outputs that would be produced by the plant in each of its different modes.

Abstract: The damper assembly has improved valve means that includes at least one annular movable valve member of the voice-coil type. Such valve member is formed at least in part of composite material that increases the strength and stiffness of the member, while reducing its coefficient of thermal expansion and its weight. In a preferred embodiment of the invention, the assembly includes two movable annular valve members which are driven in unison with each other such that when one occupies a flow-permitting position the other occupies a flow-inhibiting position. Check valves utilized in the assembly preferably are of a resilient split-ring type.

Abstract: A damper of the semi-active type is controlled such that the damping forces generated by the damper, in response to relative movement between spaced members interconnected by it, are caused to be of minimal (ideally zero) magnitude when the product of the relative displacement between the members and the relative velocity between the members is greater than zero. The foregoing control policy may be implemented by purely mechanical elements, or by electronic elements of relatively simple and inexpensive types.