Abstract: A method of isolating vibrations between vibrating bodies includes determining a pressure differential between a first fluid chamber and a second fluid chamber of a liquid inertia vibration eliminator (LIVE) unit, and selectively injecting fluid into or withdrawing fluid from the LIVE unit based on the pressure differential. A system for isolating vibrations between bodies includes a vibration isolator including fluid, a fluid regulator valve in fluid communication with the vibration isolator to selectively flow fluid through the vibration isolator, a pressurized fluid source in fluid communication with the fluid regulator to supply fluid to the fluid regulator, a controller in signal communication with the fluid regulator to control fluid flow between the fluid regulation valve and the vibration isolator, and at least one sensor in signal communication with the controller.

Abstract: A vibration control system for a rotorcraft includes at least one of an integrated actuator and an intermediate actuator associated with a first source of vibration, a sensor configured to sense vibration from the first source of vibration, a dedicated actuator configured for association with a fuselage, and a controller configured to receive information from the sensor and configured to control the dedicated actuator and the at least one of the integrated actuator and the intermediate actuator.

Abstract: A rotorcraft vibration isolation system includes a plurality of liquid inertia vibration elimination (LIVE) units mounted on a first rotorcraft surface, an accumulator mounted on a second rotorcraft surface at a location that is remote from locations of the plurality of LIVE units, and a fluid passage to connect the accumulator to the plurality of LIVE units in parallel. The fluid passage has sufficient length to traverse between the location of the accumulator and each location of each LIVE unit. During rotorcraft operation, the second rotorcraft surface experiences lesser periodic vibration than the first rotorcraft surface.

Abstract: A vibration isolation system includes a vibration isolator configured to flow a fluid. A fluid pumping system is connected to the vibration isolator. The fluid pumping system includes a fluid flow pathway configured to flow the fluid to the vibration isolator. The fluid pumping system includes a piston assembly positioned in the fluid flow pathway. The piston assembly includes a first piston and a second piston configured to displace the fluid in opposite directions through the fluid flow pathway. The vibration isolation system includes a fluid flow augmentation system, which includes an eccentric member positioned between the first piston and the second piston. The fluid flow augmentation system is configured to control a flow of the fluid to the vibration isolator through the fluid flow pathway by controlling a displacement of the first piston and the second piston through at least a partial rotation of the eccentric member.

Abstract: A method of isolating vibrations between vibrating bodies includes determining a pressure differential between a first fluid chamber and a second fluid chamber of a liquid inertia vibration eliminator (LIVE) unit, and selectively injecting fluid into or withdrawing fluid from the LIVE unit based on the pressure differential. A system for isolating vibrations between bodies includes a vibration isolator including fluid, a fluid regulator valve in fluid communication with the vibration isolator to selectively flow fluid through the vibration isolator, a pressurized fluid source in fluid communication with the fluid regulator to supply fluid to the fluid regulator, a controller in signal communication with the fluid regulator to control fluid flow between the fluid regulation valve and the vibration isolator, and at least one sensor in signal communication with the controller.

Abstract: A rotor system includes a hub assembly, a first, second, and third rotor blade rotatably attached to the hub assembly, a first, second, and third damper pivotally attached to the hub assembly and pivotally attached to the first, second, and third rotor blade, respectively, and a control system operably associated with the first, second, and third damper. A method to control vibratory forces exerted on the hub assembly via the first and second rotor blade includes separately controlling a dynamic spring rate of each of the first and second dampers with the control system.

Abstract: A rotorcraft vibration isolation system includes a plurality of liquid inertia vibration elimination (LIVE) units mounted on a first rotorcraft surface, an accumulator mounted on a second rotorcraft surface at a location that is remote from locations of the plurality of LIVE units, and a fluid passage to connect the accumulator to the plurality of LIVE units in parallel. The fluid passage has sufficient length to traverse between the location of the accumulator and each location of each LIVE unit. During rotorcraft operation, the second rotorcraft surface experiences lesser periodic vibration than the first rotorcraft surface.

Abstract: An apparatus includes an active vibration isolation system that includes a vibration isolator, a dual fluid pump in fluid communication with the vibration isolator and a hydraulic system, wherein the dual fluid pump is configured to segregate a tuning fluid from a hydraulic fluid and an electric-hydraulic servo valve in fluid communication with the dual fluid pump.

Abstract: A vibration control system for a rotor hub provides vibration attenuation in an aircraft by reducing the magnitude of rotor induced vibratory. The system can include a force generating device attached to a rotor hub which rotates along with the rotor at the rotational speed of the rotor. Vibratory shear force is generated by rotating unbalanced weights each about an axis non-concentric with the rotor hub axis at high speed to create large centrifugal forces. The rotational speed of the weights can be a multiple of the rotor rotational speed to create shear forces for canceling rotor induced vibrations. The amplitude of the generated shear force is controlled by indexing the positions of the unbalanced weights relative to each other, while the phase of the shear force is adjusted by equally phasing each weight relative to the rotor.

Abstract: The adaptive reference model algorithm uses a gain scheduling feature combined with a customized Least-Squares routine as an adaptive method for adjusting feedback control so as to account for variations in Transfer Function (G), thereby optimizing the effectiveness of the Active Vibration Control (AVC) System. The Least-Squares routine identifies the transfer function in a background process without interruption of closed loop vibration control. This identification approach is accomplished without intentional interrogation of the AVC actuators and without intentional vibration level changes. For this adaptive control logic, the dynamic relationship between AVC actuators and AVC sensors is represented by a mathematical model of Transfer Function (G). The mathematical model of Transfer Function (G) is continuously updated by the Least-Squares routine.

Abstract: The adaptive reference model algorithm uses a gain scheduling feature combined with a customized Least-Squares routine as an adaptive method for adjusting feedback control so as to account for variations in Transfer Function (G), thereby optimizing the effectiveness of the Active Vibration Control (AVC) System. The Least-Squares routine identifies the transfer function in a background process without interruption of closed loop vibration control. This identification approach is accomplished without intentional interrogation of the AVC actuators and without intentional vibration level changes. For this adaptive control logic, the dynamic relationship between AVC actuators and AVC sensors is represented by a mathematical model of Transfer Function (G). The mathematical model of Transfer Function (G) is continuously updated by the Least-Squares routine.