An aircraft includes a first rotor assembly, a second rotor assembly, and a rotor phase angle control system. The system includes a phase adjustor operably associated with the first rotor assembly and the second rotor assembly. The method includes sensing vibrations exerted on the aircraft and offsetting a phase angle of the first rotor assembly and the second rotor assembly to minimize the vibrations.

A dynamic balance device for a press machine includes a plurality of cam portions which transmit a vertical motion of a slide to a balance weight to move the balance weight in a reverse direction of the vertical motion of the slide. The cam portions are each movable in a direction substantially orthogonal to a moving direction of the slide, and each include a first inclined surface and a second inclined surface. The first inclined surface has an inclination angle corresponding to an inclination angle of an inclined surface formed on a member which is provided integrally with the slide and vertically moves with the slide. The second inclined surface has an inclination angle corresponding to an inclination angle of an inclined surface formed on the balance weight.

Systems, devices, and methods for a hub-based active vibration control (AVC) design includes at least one pair of co-rotating motorized imbalanced rotors that create a controllable rotating force vector that can be controlled to cancel hub loads on a rotating hub. This control is achievable using a configuration in which each rotor has an axis of rotation that is offset from the hub axis of rotation. In this way, in a loss of operation failure mode, the system is designed such that centrifugal forces will cause the masses to spin to an orientation of low static imbalance.

A drilling rig apparatus is disclosed for mitigating stick-slip using a saver sub that is compatible with different top drives. The saver sub includes a smart material adjustable whenever a stand is added to the drill string to have different spring characteristics to generally match the impedance of the top drive to the impedance of the drill string. The saver sub also includes a magneto rheological fluid that is adjusted whenever a stand is added to the drill string to compensate for the changed characteristics of the drill string. The damping constant implemented by the MR fluid enables the saver sub to absorb stick-slip vibrations at the top drive. Each time that a stand is connected to the drill string, the spring and damping constants may be updated to accommodate the changing characteristics of the drill string.

A drilling rig apparatus is disclosed for mitigating stick-slip using a saver sub that is compatible with different top drives. The saver sub includes a smart material adjustable whenever a stand is added to the drill string to have different spring characteristics to generally match the impedance of the top drive to the impedance of the drill string. The saver sub also includes a magneto rheological fluid that is adjusted whenever a stand is added to the drill string to compensate for the changed characteristics of the drill string. The damping constant implemented by the MR fluid enables the saver sub to absorb stick-slip vibrations at the top drive. Each time that a stand is connected to the drill string, the spring and damping constants may be updated to accommodate the changing characteristics of the drill string.

A vibration attenuation system for attenuating vibrations in a mast of an aircraft includes a weight attached to the mast but free to orbit about the mast. The weight can be comprised of one or more weight assemblies. Embodiments can include a single weight, or plural weight assemblies wherein each weight assembly can include a mechanical interconnecting mechanism so that each weight assembly receives feedback regarding the position and movement of one or more other weight assemblies. Each weight can be associated with a spring that urges the weight towards a neutral position. Rotation of the mast can cause the weight to orbit about the mast and self-excite such that the weight acts against the urging of the spring towards an attenuating position.

According to an embodiment, a driving apparatus includes a housing, a first driving body in the housing to be rotatable around a first central axis, an eccentric driving body provided in the first driving body to be rotatable around a second central axis parallel to the first central axis, a first pivot provided at one axial end of the eccentric driving body and eccentrically to the second central axis, a second pivot provided at another axial end of the eccentric driving body and eccentrically to the second central axis, a first moving body rotatably coupled to the first pivot and linearly movable along a third central axis, a first guide body which guides movement of the first moving body, and a second guide body which guides the second pivot to be movable in a first direction.

According to an embodiment, a driving apparatus includes a housing, a first driving body in the housing to be rotatable around a first central axis, an eccentric driving body provided in the first driving body to be rotatable around a second central axis parallel to the first central axis, a first pivot provided at one axial end of the eccentric driving body and eccentrically to the second central axis, a second pivot provided at another axial end of the eccentric driving body and eccentrically to the second central axis, a first moving body rotatably coupled to the first pivot and linearly movable along a third central axis, a first guide body which guides movement of the first moving body, and a second guide body which guides the second pivot to be movable in a first direction.

A balance device for an internal combustion engine includes a crankshaft and a balance shaft. The crankshaft includes a CS eccentric weight. The balance shaft includes a BS eccentric weight. A CS connected point deviated from the CS main shaft, and a BS connected point deviated from the BS axial shaft are connected with a connection rod. A CS connection mechanism that enables relative rotation of the crankshaft and the connection rod is provided at the CS connected point. A BS connection mechanism that enables relative rotation of the balance shaft and the connection rod is provided at the BS connected point. A guide section guides a motion of the connection rod so that the balance shaft rotates in an opposite direction to the crankshaft.

A balance device for an internal combustion engine includes a crankshaft and a balance shaft. The crankshaft includes a CS eccentric weight. The balance shaft includes a BS eccentric weight. A CS connected point deviated from the CS main shaft, and a BS connected point deviated from the BS axial shaft are connected with a connection rod. A CS connection mechanism that enables relative rotation of the crankshaft and the connection rod is provided at the CS connected point. A BS connection mechanism that enables relative rotation of the balance shaft and the connection rod is provided at the BS connected point. A guide section guides a motion of the connection rod so that the balance shaft rotates in an opposite direction to the crankshaft.