Abstract: Disclosed is a vibration isolator system for mounting an inertial sensor assembly (ISA) to a support that is subject to shock and vibration. The vibration isolator system includes a ring shaped elastomeric member, and ring shaped outer and inner members. Both the outer and inner members are fixed to the elastomeric member. In addition, the outer member is secured to the support and the inner member is secured to the ISA. The elastomeric member isolates the ISA from shock and vibration that may otherwise be transmitted from the support to the ISA.

Abstract: A vibration dampener adapts to different speeds of rotation. The device comprises a drive collar (1) and several inertial masses (2). The collar rotates around a central axis (3) and the inertial masses pivot around peripheral axes along the direction of rotation. Each inertial mass is secured to the collar by two bolts (5). The bolts, which extend parallel the central axis, are distributed around the circumference of the collar, and roll back and forth along arcs (6). The arcs are concave toward the central axis in the vicinity of the collar and concave in the opposite direction in the vicinity of the inertial masses. The bolts extend through a guide (7) toward the sides facing away from the associated arcs.

Abstract: A double-mass type dynamic damper mounted on a rod-shaped oscillating member, which includes a first damper system and a second damper system that are tuned to two different frequency ranges. Each of the damper systems includes a cylindrical mass member disposed radially outwardly of the oscillating member, and an elastic support member for elastically supporting the mass member with respect to the oscillating member. The elastic support members of the two damper systems are disposed in series and connected to each other in the axial direction. The dynamic damper further includes an elastic connector formed by adjacent parts of the two elastic support members, for elastically connecting axially opposed faces of the two mass members.

Abstract: A torsional vibration damper has a rotational axis and an annular housing having inner and outer members. The housing has an annular channel in which an inertia member is received. The channel has axially extending walls and is closed by an annular cover plate to retain the inertia member The inner edge of the cover plate is received in a rabbet in the inner channel wall and is joined to the wall by means of a weld. The inner and outer members are connected by an annular weld at a central hub. The weld may extend between two radial extremes which are separated by a distance substantially greater than the thickness of weld. The damper is easier to manufacture and assemble and has greater structural integrity.

Abstract: Broadband particulate absorbers include a suspended container for containing particulate beads that absorb vibration energy over a broad bandwidth so reduce coupled vibrations of mechanical systems over the broad bandwidth. The absorbers preferably include two opposing aluminum containers for containing particulate teflon beads. The aluminum containers are suspended and separated by aluminum I-beams attached to stringers of a rocket subjected during lift off to atmospheric pressure vibrations exerted on the vehicular skin coupling vibration through the stringers to trusses supporting sensitive inertial navigation payloads. The absorbers can be finely tuned using variably thick mass or various amounts of beads for reducing peak vibrations coupled into the payloads.

Abstract: A vehicle suspension system (110) having a primary suspension system (112) and a secondary suspension system (114). Vertical motion of a vehicle wheel (120) places a force on the vehicle frame (126) which, in turn, places a force on the vehicle body (124). The secondary suspension system (114) translates the relative motion between the wheel (120) and frame (126) into a force on the vehicle body (124) which is equal and opposite to the force transmitted from the frame (126) to the body (124). A frictional shock absorber (300) is utilized in the suspension system (110) as well as a multi-stage coil spring (400).

Abstract: An earthquake resistant foundation based on the method of longitudinal wave filtration by periodic or quasi-periodic septate waveguides. The generic septate waveguide comprises either a series of cylindrical or annular polymer members or a stratified medium with air-filled cylindrical channels. In all cases, the polymer members are reinforced along their torsional surfaces. As the waveguides are distributed into a specific matrix, they serve as an isolating and damping device which is placed between the source of sound, shock or vibration waves and the object of protection. The elements of the waveguide are the individual septate cylindrical cross sections, which comprise a configuration of polymer, viscous or non-viscous liquid and air constituents bonded to and separated by the rigid end plates. The method postulates that radial displacement be zero at the boundary between the polymer member and the septum. Furthermore, the polymer member should be incompressible, and the septa are rigid.

Abstract: The active vibration mount disclosed herein employs a multiplicity of layers of an electro-strictive material such as an electro-strictive polyurethane film interleaved with electrodes. A majority of the layers are employed as an output transducer while at least one layer is employed as a sensor generating a force-induced voltage. Accordingly, a feedback controller responsive to that voltage can energize the output transducer thereby to reduce the vibratory force transmitted through the mount over a preselectable range of frequencies while the mount supports a static load.

Abstract: An active vibration isolation system (10) includes a plurality of stiff actuators, such as piezoelectric motors (12a-c; 284, 350) which support a small mass (18) inside of a case (300). A passive isolator (20) is interposed between the small mass (18) and the payload mass (M.sub.p). In the instance where the stiff actuators are piezoelectric motors, the sidewalls of the case (300) are used to provide compressive force along the variable length of each of the horizontal piezoelectric motor elements (284, 350) to prevent damage to same. Compensation circuitry (24) is connected between velocity sensors (17) and the stiff actuators to control the variable length thereof in this move-out-of-the-way system (10) and to compensate for resonating modes. Optionally, a payload mass velocity sensor (26) and associated circuitry may be used to provide additional control.

Abstract: The following relates to the use of low-density granular fill with a specific gravity less than 1.5, placed in hollow cavities built into turbomachinery blades, vanes, and shafts. The granular fill provides effective damping at lower frequencies than conventional passive damping treatment due to its low bulk compressional sound speed. Selected materials used for the granular fill treatment are chosen for specific turbomachinery needs, including temperature of operation. Rotation speed is also a factor because it induces on the granular material an apparent hydrostatic pressure associated with the centripetal acceleration, and sound speed in granular materials is a function of pressure raised to the power 1/n. Preferred designs for placement of low-density granular material in appendages and shafts are found using an iterative design tool based on the Direct Global Stiffness Matrix method.

Abstract: A tuned mass damper incorporating a container with an inside surface, two end portions and a mass mounted for oscillation between the end portions by a pair of bias springs, the two end portions being filled with a compressible gas to reduce the effects of temperature variations on the damping characteristics, to increase the damping with increased amplitude of oscillation of the mass and to minimize size and weight of the damper, the mass being supported for oscillation by using a plurality of grooves at each end of the mass with a single ball in each groove to provide frictionless and self centering motion of the mass.

Abstract: An active shock-absorbing boat seat system has a seat system mounted to the boat deck through an active shock absorber. Sensors monitor both the shock to be passed from the deck to the seat as well as the shock actually received by the seat after passing through the shock absorbing system. A controller monitors the shock levels and provides a continuing control signal to the shock-absorbing unit to control the response of the shock-absorbing unit during the duration of the shock. The control system can provide for adjustment of various operating parameters for the system, including initial position of the seating system, overall ride stiffness, maximum allowable shock, and other parameters.

Abstract: A damping mounting structure for use between two members for isolating motion changes which incorporates a plurality of dampers connected between the two members with spring members operating in parallel with the dampers to provide stiffness and where the springs are pneumatic to provide proper stiffness when the load is heavy without damage to the springs and/or to provide variable stiffness when desired.

Abstract: A horizontal frequency vibration pendulum isolator which comprises a pendulum which has an upper end flexibly secured to a vertical isolator. The pendulum is received within a hollow leg and is supported at its lower end by pendulum wires which wires are secured to the hollow leg which is grounded. The wires are specifically angled with reference to the longitudinal axis of the pendulum to impart to the horizontal isolator a known or designed horizontal stiffness.

Abstract: A vibration damping arrangement for a gondola of a type having a supporting unit attached to a cable, a hanger suspended from the supporting unit and a carriage suspended from the hanger. A vibration damping device includes an elongated hollow housing. A bottom plate of the housing defines a downwardly arcuate oscillation track which extends in a direction perpendicular to the cable. A vibration damping body is movably located on the oscillation track such that it can naturally oscillate on the oscillation track in the longitudinal direction of the oscillation track upon vibrations of the carriage. The vibration damping device is located under a seat inside the carriage, suspended from a bottom of the carriage, supported by the hanger above a roof of the carriage or mounted on the roof of the carriage in such a manner that it does not extend beyond width and length of the carriage. The vibration damping device does not substantially occupy a passenger room so that comfortableness is not degraded.

Abstract: The invention is an apparatus for connecting a slender structure to a reference body. The apparatus comprises a link, that is connected to one end of the slender structure. The link is connected with a hinge at a second point of the link to the reference body with at least one degree of rotational freedom. A damper for damping motion of the link through at least one of the link's degrees of rotational freedom is connected between the link at a third point and the reference body. The device suppresses vibration waves travelling in the slender structure. A spring for resisting motion through the degree of rotational freedom may also be beneficially provided. The link, spring and damper may all act through one or two degrees of rotational freedom. The hinge can be either a pivot or a flex joint. The invention includes a method of selecting the parameters of the link, damper and spring assembly to optimize the suppression of vibration.

Abstract: A tuned mass damper using a single predetermined mass connected to springs of predetermined stiffness along each of at least two directions to absorb energy from a vibrating structure to which it is attached and damp the vibrations in a rapid and efficient manner with a minimum of weight and volume used.

Abstract: An elongate stabilizer for an archery bow includes an elongate housing having a plurality of separate internal chambers suitable to receive damping material or damping devices therein. One end of the stabilizer may be mounted on a bow riser in normal manner. In a preferred embodiment of the stabilizer, separate chambers extend inwardly from opposite ends of the elongate housing and are closed by end pieces secured to the opposite ends of the housing. The chambers are separated by an intermediate portion of the housing. Damping material or devices may be contained in one or more of the chambers and when more than one chamber contains damping material or devices, such damping material or devices may be of different types.

Abstract: Vibration of a structure is damped using vibration damping mechanisms. Each vibration damping mechanism has a first plate rotatably mounted on a pair of first pivot shafts respectively mounted on a pair of opposed frame members of the structure, a second plate which is rotatably mounted on a pair of second pivot shafts respectively mounted on the opposed frame members at a predetermined distance from the first pivot shafts and is opposed to the first plate intervening a space therebetween, and a viscoelastic body provided in the space between the first and second plates. A plurality of vibration damping mechanisms having viscoelastic bodies different from each other in mechanical properties are mounted between the opposed frame members and a conversion coefficient .beta.

Abstract: A seismic shock isolator and method of strengthening structures against seismic shock is disclosed. The shock isolator includes a cylinder having a damping chamber and an accumulator chamber and a piston movable into the damping chamber. The damping chamber can contain compressible liquid or incompressible liquid. The piston has a damping head and a first control orifice, and the accumulator chamber is separated from the damping chamber by a wall having a second control orifice having a higher exponent than the first control orifice. Movement of the piston into the damping chamber creates a combination of damping and stiffening having a spring component. When the isolator has compressible liquid therein, the spring and stiffening is produced by a compression of the liquid. When the isolator contains an incompressible liquid, the stiffening and spring component are obtained by a yielding of a column which movably supports the wall which divides the damping chamber from the accumulator chamber.

Abstract: A method and system/apparatus implementing a non-model based Decentralized Feedforward Adaptive Algorithm (DFAA) for active vibration control of an actively-driven element, such as an Active Vibration Absorber (AVA) (24). The AVA (24)preferably includes an inertial tuning mass (42) and a voice coil assembly (46) and is contained in an active vibration control system (20) wherein the method and system/apparatus reduce vibration of a vibrating member (22) at an attachment point (26) by receiving an error signal from an error sensor (28) such as an accelerometer and a reference signal from a tachometer (32) or accelerometer (34), where the reference signal is correlated to, or indicative of the frequency content of, a primary vibration source (36) and calculating an updated output signal via an electronic controller (39) using the non-model based DFAA to dynamically drive the actively-driven element, such as AVA (24).

Abstract: A vibration isolation system comprises four tunable dual-axis hydraulic inertial isolators, an array of accelerometers, and a controller. The controller inputs signals from the accelerometers and outputs signals to tune the isolators to minimize the vibration transmitted from a vibrating body to an isolated body. The isolators are tuned by varying the dimensions of their tuning passages or by application of magnetohydrodynamic force to the liquid within the tuning passages.

Abstract: The present invention is an improved flywheel for damping vibrations in a coating roll. The improved flywheel has an inner plate and an outer plate and sandwiched between the two plates are alternating rings of a solid body material such as aluminum or steel and conventional vibration damping material. Typically, the flywheel is attached to the coating roll outside of the bearing mounting block. The flywheel is designed such that movement of the inner and outer plates relative to each other works to compress the damping material sandwiched between the two plates. The plates are fastened together so that torsional motion between the plates, alternating rings, and coating roll is prevented. This compression of the damping material results in the absorption and dissipation of vibrational energy of the radial bending of the coating roll.

Abstract: Vibration damping devices for skis and other applications, the damping devices comprising a Cantilevered Impact/Friction Damper (CIFD) and an Improved Constrained Layer Damper (ICLD), the CIFD including a frame affixed to a portion of the vibrating body and having a cantilevered tubular member adapted for oscillation relative to the frame such that when subject to high amplitude vibration, a free end of the tubular member having a mass alternately strikes a pair of confronting stops, the tubular member having a plurality of particles disposed therein which dissipate low amplitude vibration through inter-particle friction; the ICLD comprising a spacer member having at least one layer of viscoelastic material and at least one constraining layer attached thereto, the spacer member having a plurality of slots spaced along the longitudinal extent thereof to reduce the bending stiffness of the spacer member without diminishing the damping effect.

Abstract: A mass supported on a structure is driven by an actuator such that it moves in a direction of a vibration of the structure. A mechanism for detecting state variables relating to the vibration of the structure and a Kalman filter for performing a predetermined calculation processing on the state variables by comparing with a structure model included therein are provided in order to estimate proper values of state variables. From these state quantifies, control input values are calculated based on an optimal feedback gain matrix preset on the basis of an optimal regulator theory, and applied to control the actuator. With this configuration, the vibration of the mass due to a high-order vibration mode of the structure and the vibration of the mass caused by the compressibility of a hydraulic oil or the response characteristics of a servo valve are efficiently suppressed.

Abstract: An active vibration isolation system (10) includes a plurality of stiff actuators, such as piezoelectric motors (12a-c; 284, 350) which support a small mass (18) inside of a case (300). A passive isolator (20) is interposed between the small mass (18) and the payload mass (M.sub.p). In the instance where the stiff actuators are piezoelectric motors, the sidewalls of the case (300) are used to provide compressive force along the variable length of each of the horizontal piezoelectric motor elements (284, 350) to prevent damage to same. Compensation circuitry (24) is connected between velocity sensors (17) and the stiff actuators to control the variable length thereof in this move-out-of-the-way system (10) and to compensate for resonating modes. Optionally, a payload mass velocity sensor (26) and associated circuitry may be used to provide additional control.

Abstract: An active vibration removing apparatus having an air-spring as an actuator, includes: a vibration removing table, a supporting air-spring for supporting the vibration removing table, a servo-valve for adjusting the pressure of the air-spring, and a feedback system for controlling the servo-valve. A pseudo-differentiator pseudo-differentiates a speed adjustment signal of a device placed on the vibration removing table. A pulse selector for selects an arbitrary numbers of pulse waveforms from a series of pulse waveforms outputted from the pseudo-differentiator. The output of the pulse selector is feedforwarded in the feedback system.

Abstract: An actively-controlled resonant-type force generator (20) is adapted to be attached to a structure (21), and includes a mass (23) mounted for movement relative to the structure and a plurality of springs (22, 24) operatively arranged between the mass and the structure. A servoactuator (26) is arranged to controllably excite the mass-spring system. The actual force (F.sub.a) transmitted from the mass to the structure is compared with a commanded force (F.sub.c) to produce a force error signal (F.sub.e). The actuator is caused to produce a velocity as a function of the error signal. The gain of the closed force loop is selected so that the resonance of the mass-spring system has an effective damping ratio (.zeta.) greater than about 0.5, and preferably about 0.7. Thus, the mass-spring system will not be substantially resonantly excited by vibrations of the structure near its resonant frequency (.omega..sub.n).

Abstract: A weight collar for use with a stabilizer adapted to be connected to a bow. The weight collar is removably connected to a stabilizer outer peripheral surface of the stabilizer. The weight collar includes a pad constructed of a compressible material whereby the weight collar is movable in upwardly and downwardly directions perpendicular to an axial center line of the weight collar and movable in angular directions relative to the axial center line of the weight collar while remaining attached to the weight collar. A stabilizer for use with a bow having a stabilizer tube with an opening extending therethrough forming a stabilizer chamber, the stabilizer chamber defining a stabilizer in a peripheral surface. A resonator suppressor ring is disposed in the stabilizer chamber between the first and the second ends of the stabilizer tube.

Abstract: A ball screw device includes a screw shaft including a hollow hole, a vibration controlling mass member inserted into the hollow hole, a rubber member or a synthetic resin member which is interposed between the outer surface of the vibration controlling mass member and the inner surface of the hollow hole of the screw shaft to prevent contact between the vibration controlling mass member and hollow hole. Further, the ball screw device includes vibration controlling mass member hold rings respectively interposed between the outer surface of the vibration controlling mass member and the inner surface of the hollow hole of the screw shaft and providing two or more support points spaced from each other in the axial direction of the mass member, with slight clearances being provided at least between the outside diameter surfaces of the hold rings and the inside diameter surface of the hollow hole.

Abstract: The invention provides a vibration cancellation device for rigidly mounting to or forming part of an apparatus subject to vibration. The device comprises a mass supported by magnetic levitation but which is magnetically driven to provide vibration cancelling relative movement, movement sensors controlling the application of power, in a relative motion cancellation direction.

Abstract: The invention concerns the use of actively tuned liquid dampers to quench vibrations in large civil structures. Such vibrations may be induced by earthquakes or high winds. The effective length of the liquid damper tank determines the natural frequency of the liquid, and thus the effectiveness of the damper at particular excitation frequencies. The liquid damper is tuned by rotating baffles to regulate the effective length of the damper tank.

Abstract: A resonance absorber for the damping of structure-borne vibrations has a number of freely swinging slats with different resonance frequencies. The slats are arranged on a common base which can be connected with a body to be damped, and are constructed as double slats comprising a damping coating which is in each case squeezed between the two slats elements.

Abstract: A hydrostatic anti-vibration system includes a main tank provided on a construction to be suppressed from vibrating and having a main tank body of substantially flat rectangular configuration. Hollow vertical extensions extend upwardly from peripheral edge portions of the main tank body and are filled with a working liquid at a predetermined level with upper air chambers maintained thereabove. Ducts communicate the upper air chambers of the hollow vertical extensions. Intermediate tank portions are disposed at the intermediate portions of respective ducts and contain a vibration suppressing liquid. A pivotal plate is disposed in each of the intermediate tank portions to separate the interior space of the intermediate tank portion into a pair of chambers respectively connected to corresponding portions of the duct. The plate pivots in response to flow pressure of the vibration suppressing liquid. A damping mechanism provides a resistance against displacement of the pivotal plate.

Abstract: The stiffening girder type suspension bridge according to the present invention is designed with a smaller dead load under normal conditions, and applied with a temporary dead load as an additional mass to improve the static characteristics and aerodynamic stability when the bridge is subjected to particularly violent storms that result in significant vibrations and swaying of the bridge. The present invention bridge structure is highly economical. A passage is provided in the stiffening girder at the center of its width along the direction of the bridge axis, so that a temporary dead load as an additional mass can be moved into the passage. Under normal conditions, the passage is kept empty of the load. When an imminent storm is anticipated, a given amount of liquid or solid is transferred into the passage located within the stiffening girder to temporarily apply a given amount of temporary dead load to the stiffening girder during a storm to control vibrations of the bridge caused by the winds.

Abstract: The invention is an apparatus for connecting a slender structure to a reference body. The apparatus comprises a link, that is connected to one end of the slender structure. The link is connected with a hinge at a second point of the link to the reference body with at least one degree of rotational freedom. A damper for damping motion of the link through at least one of the link's degrees of rotational freedom is connected between the link at a third point and the reference body. The device suppresses vibration waves travelling in the slender structure. A spring for resisting motion through the degree of rotational freedom may also be beneficially provided. The link, spring and damper may all act through one or two degrees of rotational freedom. The hinge can be either a pivot or a flex joint. The invention includes a method of selecting the parameters of the link, damper and spring assembly to optimize the suppression of vibration.

Abstract: A wire cable isolator and an associated energy absorbing restraint for connecting between a device subject to movement due to dynamic loads and possibly thermal deflection, and an adjacent structure, such as a building or a support member is disclosed. The isolator has predetermined, symmetrical force-deflection properties. The isolator includes first and second pairs of entrapment members, and a wire cable formed in a spiral. The first pair of entrapment members clamp the wire cable spiral at opposite side of the spiral and the second pair of entrapment members clamp the wire cable spiral at opposite sides of the spiral. The first and second pair of entrapment members are disposed at predetermined positions about an exterior periphery of the spiral.

Abstract: Vibrations of pipes or other components installed in a container such as a tank intended for holding liquids, are damped by surface area damping bodies, e.g. plates with through-holes that are immersed in the liquid in the container. These plates are rigidly connected to the pipes or components to be damped. The vibration damping plates are constructed of metal, for example, and the through-holes reduce the mass and advantageously affect the damping effect. The materials for making the perforated damping plates are selected to be compatible with the content of the containers, such as a fuel in a tank in a spacecraft. The surface area ratio of all cross-sectional areas of the through-holes to the total plate surface area is optimized to achieve a maximum damping effect. These perforated plates are secured to pipes, braces, filters, ducts, or other internal components of fuel tanks of land vehicles, aircraft, and spacecraft.

Abstract: A mount assembly for a vibrating component, which mount includes a supported mount supported on a machine part; a supporting mount supported via a spring element on the supported mount; and an inertial mass, movable back and forth by a drive in a direction parallel to the direction of the vibrations introduced during operation. The inertial mass is spring-mounted and is controllably movable in a direction opposite from the exciting vibration and is joined to the supported mount by a spring, such that the inertial mass and spring are not contacted by a liquid. A control system is used to control the movement of the inertial mass.

Abstract: A brake shoe (14) for an internal drum brake assembly (10) having a mass damper (60) is disclosed for attenuating objectionable noise. The mass damper (60) is attached to an arcuate table (40) of a brake shoe (14) at a predetermined location adjacent to an anti-node corresponding to a flutter mode of vibration. The mass damper (60) is disposed adjacent to an arcuate edge 56 of the arcuate table (40).

Abstract: A nonlinear shock absorber is disclosed. The device has a housing filled with hydraulic fluid and contains a relatively heavy mass or piston supported by a helical coil. The helical coils disposed and shaped so as to provide a nonlinear resistance to a shock applied to the housing. During shock absorption fluid flows contra to the piston movement with a corresponding elongation of the helical coil spring causing the coil spring to engage an inner wall of the housing to provide for frictional dampening.

Abstract: A composite structure of elastic and viscoelastic components in which dynamic loads are effectively damped by repeated transmission through viscoelastic layers. Multiple viscoelastic layers and stiff segmented elastic layers are formed on the outside of a tubular layer of soft elastic material, to provide the damping effect without having to form additional layers inside the tubular layer of soft elastic material. The transition temperatures above which the viscoelastic layers become substantially less stiff may be selected to be different for each layer, to provide increased damping efficiency over a broadened operative temperature range.

Abstract: An antivibration/antishock device comprising a carrier element (11) and a carried element (12) linked by cable (13a, 13b), wherein the carrier and carried elements each have at least two anchoring points for the cable placed in the neighborhood of the apices of a polygon with n apices, wherein the cable is alternately anchored to a point (140) of the carrier element (11) and to a point (141, 141') of the carried element (12) and is oriented on the anchoring points (140) of a first (11) at least of said elements in a roughly transverse direction to the radial direction, wherein the carrier or carried element is a modular element (11a, 11b) comprising, on the one hand, individual anchoring modules (11a, 11b) and, on the other, assembly means (15, 17, 21) of said modules, and, further, while the process is one wherein:in a first so-called `anchoring` phase, the cable is anchored, on the one hand, in each of said anchoring modules of the modular element, and, on the other, in the other element, andin a second pha

Abstract: A dynamic vibration absorber for a rotating machinery element preferably of the bifilar pendulum vibration absorber type wherein the absorber system includes one or more pair(s) of masses having identical paths of movement relative to the axis of the rotating element whose vibrations are being absorbed, the individual absorber masses of a given pair moving out-of-phase with respect to one another relative to the rotating element wherein a disturbance torque with a frequency that is a multiple of the rotation rate of the rotating element is absorbed by a one-half relative frequency motion of the corresponding half-order absorber pair. The half-order absorber pairs are driven primarily by centrifugal forces, move with a frequency one-half that of the disturbance torque and use non-linear Coriolis forces as the source of the counteracting torque.

Abstract: A vertical vibration elimination table apparatus has a vibration elimination table supported by actuators at four portions thereof. The actuators are operable in response to signals which are fed back thereto and which are indicative of vertical positions and vertical accelerations of the four portions of the table. A control apparatus for controlling and driving the actuators includes a 4-degree-of-freedom motion mode extraction circuit for extracting motion mode error signals of four degrees of freedom including one degree of freedom for translational motion, two degrees of freedom for rotations and one degree of freedom for twist motion, a compensation circuit for producing compensated motion mode signals by effecting compensations on the respective motion mode error signals, and a motion mode distribution circuit for producing drive signals based on the compensated motion signals and delivering the drive signals to the respective actuators.

Abstract: An active vibration control subassembly for a structure (such as a jet engine duct or a washing machine panel) undergoing bending vibrations caused by a source (such as the clothes agitator of the washing machine) independent of the subassembly. A piezoceramic actuator plate is vibratable by an applied electric AC signal. The plate is connected to the structure such that vibrations in the plate induced by the AC signal cause canceling bending vibrations in the structure and such that the plate is compressively pre-stressed along the structure when the structure is free of any bending vibrations. The compressive prestressing increases the amplitude of the canceling bending vibrations before the critical tensile stress level of the plate is reached. Preferably, a positive electric DC bias is also applied to the plate in its poling direction.

Abstract: An actively-controlled resonant-type force generator (20) is adapted to be attached to a structure (21), and includes a mass (23) mounted for movement relative to the structure and a plurality of springs (22, 24) operatively arranged between the mass and the structure. A servoactuator (26) is arranged to controllably excite the mass-spring system. The actual force (F.sub.a) transmitted from the mass to the structure is compared with a commanded force (F.sub.c) to produce a force error signal (F.sub.e). The actuator is caused to produce a velocity as a function of the error signal. The gain of the closed force loop is selected so that the resonance of the mass-spring system has an effective damping ratio (.zeta.) greater than about 0.5, and preferably about 0.7. Thus, the mass-spring system will not be substantially resonantly excited by vibrations of the structure near its resonant frequency (.omega..sub.n).

Abstract: A thixotropic material is charged in a container. The container also holds a movable member which is placed in the thixotropic material so as to stir the thixotropic material. A force transmitting element is connected to the movable member. When an object, the vibration of which is to be controlled, is out of resonance, the amplitude of vibration is so small that the thixotropic material is in a gel state, thus presenting a comparatively large spring constant for the vibration control apparatus. As the excitation frequency is increased towards the resonance range, the amplitude of vibration is increased correspondingly, so that the movable member stirs the thixotropic material to generate stress in the latter, whereby the phase of the thixotropic material is changed from gel to sol. Consequently, the natural frequency of the vibration system, including the object and the vibration control apparatus, is lowered, thus averting resonance.

Abstract: A dynamic vibration absorber includes a movable weight portion, and a movable portion magnet assembly provided for the movable weight portion. The movable portion magnet assembly includes a magnet train having a plurality of cylindrical magnets disposed coaxially in such a manner that adjacent cylindrical magnets have different adjacent magnetic poles. A fixed portion is provided in opposed relation to the movable weight portion and a fixed portion magnet train is provided on the fixed portion and includes a plurality of magnets having magnetic poles different, in a stationary state, from opposed magnetic poles of the cylindrical magnets. The movable weight portion is preferrably disposed in a vessel.

Abstract: The invention relates to an active wheel supporting system for vehicles having a scanning device which registers surface unevenness in a roadway, and active wheel support assemblies which are controlled by the scanning device so that the wheels are actively adjusted to the registered surface unevenness. To avoid acceleration of the vehicle body, wheel support assemblies are coupled in each case to counter-masses which carry out movements opposite to the wheel movements relative to the vehicle body. The reaction forces exerted on the body by the wheel movements are thus compensated by reaction forces directed in the opposite direction due to the simultaneous movement of the counter-masses.