Abstract: A system for reducing vibrations in a rotating system uses a variable viscosity medium that is redistributed in a housing connected to the rotating system. Specifically, the medium is responsive to a control signal that is generated as a function of rotational speed of the rotational system. The control signal activates a triggering device that promotes a change in viscosity of the medium such that it is distributed within the housing in a manner that reduces vibratory loads.

Abstract: A system for reducing vibrations in a rotating system uses a variable viscosity medium that is redistributed in a housing connected to the rotating system. Specifically, the medium is responsive to a control signal that is generated as a function of rotational speed of the rotational system. The control signal activates a triggering device that promotes a change in viscosity of the medium such that it is distributed within the housing in a manner that reduces vibratory loads.

Abstract: A noise or vibration control system reduces a sampling rate and reduces a control rate to improve computation efficiency. The present invention permits the use of a sample frequency (fs) that is less than twice the frequency of interest (fd). The sensed signals are filtered to extract a particular frequency range with a lower bound given by (2n?1)*fs/2 and an upper bound given by (2n+1)*fs/2, where n is an integer chosen so that the frequency of interest (fd) is within the extracted frequency range. The control commands are also calculated at a reduced rate, which is dependent upon the bandwidth of the tone, rather than the absolute frequency of the tone. Rather than updating the control signals directly on the sampled sensor data yk as it enters the computer, the control computations are done on the harmonic components ak and bk, or equivalently on the magnitude and phase.

Abstract: In a method for reducing sensed physical variables generating a plurality of control commands are generated at a control rate as a function of the sensed physical variables. An estimate of a relationship between the sensed physical variables and the control commands is also is used in generating the plurality of control commands. The estimate of the relationship is updated based upon a response by the sensed physical variables to the control commands. The generation of the control commands involves a quadratic dependency on the estimate of the relationship and the quadratic dependency is updated based on the update to the estimate.

Abstract: An active vibration control system provides a mass which is movable through a large excursion while minimizing the system size in two of three dimensions to compensate for sensed vibrations. A first rotating member is rotatable about a first axis and a second rotating member is rotatable about a second axis to drive a belt mounting a mass. The first axis is offset from the second axis such that as the members are rotated, the belt is driven about an elongated path. This arrangement generates an impulsive vibratory force as the mass passes over each of the rotating members and quickly changes direction. A belt including a sinusoidal mass distribution generates a vibratory force that is a smooth sinusoidal output. Multiple systems are suitably usable in conjunction with one another to provide a wide range of vibratory outputs.

Abstract: A multi-element rotor blade includes a main element and an active slat movable relative to the main element. The slat rotates and translates relative to the main element from a base position. The base position provides a compromise between minimum coefficient of drag CD and maximum coefficient of lift CLmax. In the advancing blade, since the airspeed thereof is significantly greater than the retreating blade, the slat is positively rotated from the base position to minimizes drag at low angles of attack. In the retreating blade, since the airspeed thereof is significantly lower than the advancing blade, the slat is negatively rotated and translated to maximize the coefficient of lift CLmax.

Abstract: An elastomeric coupler assembly having a helical elastomeric bearing movably supports an active slat relative to a main element. An inner elastomeric coupler assembly and an outer elastomeric coupler assembly support the slat therebetween. Centrifugal force operates to drive the slat to a first position and an actuator rod operates in tension to pull upon the inner elastomeric coupler assembly to drive the slat in opposition to the centrifugal force to a second position. The helical elastomeric bearing is layered such that it defines a section of a circular helix. The circular helix provides a coupling, which converts a linear input parallel to a virtual hinge axis into a rotary output to pitch the slat. In operation, centrifugal force operates to slide the slat outboard toward the blade tip such that the attached slat moves elastomerically along the helical arc of the helical elastomeric bearing to rotate the slat nose down.

Abstract: A multi-element rotor blade includes a main element and an active slat movable relative to the main element. The slat rotates and translates relative to the main element from a base position. The base position provides a compromise between minimum coefficient of drag CD and maximum coefficient of lift CLmax. In the advancing blade, since the airspeed thereof is significantly greater than the retreating blade, the slat is positively rotated from the base position to minimizes drag at low angles of attack. In the retreating blade, since the airspeed thereof is significantly lower than the advancing blade, the slat is negatively rotated and translated to maximize the coefficient of lift CLmax.

Abstract: An elastomeric coupler assembly having a helical elastomeric bearing movably supports an active slat relative to a main element. An inner elastomeric coupler assembly and an outer elastomeric coupler assembly support the slat therebetween. Centrifugal force operates to drive the slat to a first position and an actuator rod operates in tension to pull upon the inner elastomeric coupler assembly to drive the slat in opposition to the centrifugal force to a second position. The helical elastomeric bearing is layered such that it defines a section of a circular helix. The circular helix provides a coupling, which converts a linear input parallel to a virtual hinge axis into a rotary output to pitch the slat. In operation, centrifugal force operates to slide the slat outboard toward the blade tip such that the attached slat moves elastomerically along the helical arc of the helical elastomeric bearing to rotate the slat nose down.

Abstract: In a method for reducing sensed physical variables generating a plurality of control commands are generated at a control rate as a function of the sensed physical variables. An estimate of a relationship between the sensed physical variables and the control commands is also is used in generating the plurality of control commands. The estimate of the relationship is updated based upon a response by the sensed physical variables to the control commands. The generation of the control commands involves a quadratic dependency on the estimate of the relationship and the quadratic dependency is updated based on the update to the estimate.

Abstract: An active vibration control system provides a mass which is movable through a large excursion while minimizing the system size in two of three dimensions to compensate for sensed vibrations. A first rotating member is rotatable about a first axis and a second rotating member is rotatable about a second axis to drive a belt mounting a mass. The first axis is offset from the second axis such that as the members are rotated, the belt is driven about an elongated path. This arrangement generates an impulsive vibratory force as the mass passes over each of the rotating members and quickly changes direction. A belt including a sinusoidal mass distribution generates a vibratory force that is a smooth sinusoidal output. Multiple systems are suitably usable in conjunction with one another to provide a wide range of vibratory outputs.

Abstract: A noise or vibration control system reduces a sampling rate and reduces a control rate to improve computation efficiency. The present invention permits the use of a sample frequency (fs) that is less than twice the frequency of interest (fd). The sensed signals are filtered to extract a particular frequency range with a lower bound given by (2n−1)*fs/2 and an upper bound given by (2n+1)*fs/2, where n is an integer chosen so that the frequency of interest (fd) is within the extracted frequency range. The control commands are also calculated at a reduced rate, which is dependent upon the bandwidth of the tone, rather than the absolute frequency of the tone. Rather than updating the control signals directly on the sampled sensor data yk as it enters the computer, the control computations are done on the harmonic components ak and bk, or equivalently on the magnitude and phase.