Abstract: A vibration suppression system and method for a wind turbine comprising blades is provided. The system comprises, for each blade, a stabilization system comprising a gyroscope with a control axis extending in a first direction, a first rigid body control axis extending in a second direction different from the first direction, a second rigid body control axis extending in a third direction different from the first and second directions and a flywheel rotatable in respect of the control axis and free to move in respect of at least one of the rigid body control axes. The stabilization system comprises an actuator to apply a torque over the gyroscope, and a respective sensor to detect the motions of each blade. The suppression system comprises a control device for controlling the actuation of the actuators according to said detections, in order to suppress unwanted motions of the blades.

Abstract: An exemplary rotorcraft includes a power train with an engine coupled to a gearbox, a main rotor blade having a mast coupled to the power train, a control input linkage in communication between a pilot input device and the main rotor blade configured to communicate a control input force from the pilot input device to the main rotor blade, and a counterweight system in connection with the control input linkage and the power train to apply a centrifugal force to the control input linkage.

Abstract: 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.

Abstract: A rotor assembly for helicopter vehicles for stabilizing the aircraft and thus providing an easy way of controlling pitch and roll of the aircraft by respectively associated magnetic actuators. The rotor assembly comprises a rotor with two flexible rotor blades, a rotor head rotationally coupled to the rotor shaft, a rotating swash plate, with at least three fly bars extending therefrom. The swash plate is rotationally coupled to the rotor shaft and adjusted to tilt in all directions relative to a plane perpendicular to the rotor shaft. The rotor head is hinged to the rotor shaft in one direction so that the rotor head and the rotor blades jointly are not able to tilt around their transversal axis. The coupling between the rotating swash plate and the rotor head provide synchronized tilt movements between the rotor head and the rotating swash plate around the longitudinal axis of the rotor head.

Abstract: A method of determining at least one rotation parameter of a wind turbine rotor rotating with a rotation speed and a phase is provided. The method comprises the steps of: measuring an effective centrifugal force acting in a first pre-determined direction, which is defined in a co-ordinate system rotating synchronously with the rotor, on at least one reference object located in or at the rotor, establishing a first angular frequency representing the rotation speed of the rotor on the basis of variations in the measured effective centrifugal force due to gravitational force, establishing a second angular frequency representing the rotation speed of the rotor by use of at least one yaw rate gyro, and establishing the value of the rotation speed as the rotational parameter by correcting the second angular frequency by comparing it to the first angular frequency.

Abstract: A method and arrangement of controlling blade pitch angle of a set of rotor blades. The method comprises providing a target blade pitch angle to a controller mounted on the rotor; measuring the speed of rotation of the rotor using a rate gyro mounted on the rotor; calculating the blade pitch angle required to match the target blade pitch angle by summing the target blade pitch angle and the measured rotational speed; and actuating the blades to the calculated blade pitch angle.

Abstract: The present invention relates to a method for damping oscillations in a wind turbine comprising a wind turbine tower, a nacelle arranged on top of said wind turbine tower, and a number of rotor blades rotatably connected to the nacelle. The oscillations to be damped originate from forces induced on the nacelle and the wind turbine tower by the rotating rotor blades. The method comprises the steps of providing an internally suspended pendulum mass structure being operationally connected to an upper tower section, providing a platform being fixedly attached to the upper tower section, and providing damping means comprising one or more friction members being displaceably arranged relative to the platform, the one or more friction members being adapted to be displaced relative to the platform in response to relative movements between the suspended pendulum mass structure and the platform in order to dissipate energy from the suspended pendulum mass structure by friction.

Abstract: A wind turbine includes a yaw spring return assembly to return the nacelle from a position to which it has been rotated by yawing forces, thus preventing excessive twisting of the power cables and control cables. It also includes negative coning restrainers to limit the bending of the flexible arms of the rotor towards the tower, and stop means on the rotor shaft to orient the blades in a vertical position during periods when the unit is upwind when the wind commences. A pendulum pitch control mechanism is improved by orienting the pivot axis for the pendulum arm at an angle to the longitudinal axis of its support arm, and excessive creep is of the synthetic resin flexible beam support for the blades is prevented by a restraining cable which limits the extent of pivoting of the pendulum during normal operation but which will permit further pivoting under abnormal conditions to cause the rotor to stall.

Abstract: An improvement to a rotating blade is disclosed in a device that will apply variable moment forces to wind blades which are counter to the variable forces normally encountered in typical wind blades. The device consists of a gyro attached to the rotating blade and because of the torque force obtained by gyroscopic precession, the device will provide moment forces counter to normal blade wind forces. This invention shows a unique arrangement where the gyro is attached to the blade by a gyro positioner which adjusts the gyro's precessional rate. The gyro's precessional rate is varied with the blade's deflection or blade stress so that the gyro will impose a moment force counter to the cyclic deflection in the blade. Thus the device prevents or reduces the vibrational deflection and resultant stresses in the blades and its associated structures.

Abstract: A wind turbine of the type having an airfoil blade (15) mounted on a flexible beam (20) and a pitch governor (55) which selectively, torsionally twists the flexible beam in response to wind turbine speed thereby setting blade pitch, is provided with a limiter (85) which restricts unwanted pitch change at operating speeds due to torsional creep of the flexible beam. The limiter allows twisting of the beam by the governor under excessive wind velocity conditions to orient the blades in stall pitch positions, thereby preventing overspeed operation of the turbine. In the preferred embodiment, the pitch governor comprises a pendulum (65,70) which responds to changing rotor speed by pivotal movement, the limiter comprising a resilient member (90) which engages an end of the pendulum to restrict further movement thereof, and in turn restrict beam creep and unwanted blade pitch misadjustment.

Abstract: An improvement to rotating blades is disclosed in a device that will impose anti-moment forces and result in less stress in the said rotating member. The device consists of a rotating body or gyro which is attached to the said rotating blades, and due to the precession of the gyros, a moment is developed which is counter to the moment forces that are normally imposed on the said blades.

Abstract: A system is disclosed for controlling the pitch angle of helicopter rotor blades to compensate for differences in lift generated by advancing and retreating blades during translational flight or due to gust loading of individual blades. Each rotor blade is free to move about its pitch axis to achieve an adjustable balance between a pitching moment exerted by the blade and centrifugal force exerted by weights rotating with the blade system. Collective and cyclic pitch commands from the pilot are transmitted through a conventional swash plate to a linkage which adjusts the relationship of the pitching-moment and centrifugal forces which produces a balanced condition. The system maintains near-constant blade lift as the blade rotates, and minimizes blade distortion and asymmetric coning, thereby significantly reducing vibration arising from a shifting of the center of mass of the rotor-blade system away from the center of rotation.

Abstract: A stabilizer bar has an aerodynamically shaped member, such as a winglet, on opposite ends thereof, and the bar is connected to rotate on its longitudinal axis and is mounted to tilt about a pivot axis at right angles thereto connecting it to a rotor shaft that also carries a pair of rotor blades the pitch of which can be changed about their longitudinal axis, that is parallel with the stabilizer bar pivot axis. A pair of oppositely directed mixing levers on opposite sides of the rotor shaft and connected parallel with the stabilizer bar for tilting movement therewith are connected by first control linkages to diametrically opposite sides of a wobble plate assembly, and by second control linkages to vary the pitch of the pair of rotor blades. An arm attached to the stabilizer bar in the plane of the aerodynamically shaped members has an end disposed in alignment with the pivot axis of the stabilizer bar that is connected by a control rod to the wobble plate assembly 90.degree.

Abstract: A wind turbine having a flexible central beam member supporting aerodynamic blades at opposite ends thereof and fabricated of uni-directional high tensile strength material bonded together into beam form so that the beam is lightweight, and has high tensile strength to carry the blade centrifugal loads, low shear modulus to permit torsional twisting thereof for turbine speed control purposes, and adequate bending stiffness to permit out-of-plane deflection thereof for turbine yard control purposes. A selectively off-set weighted pendulum member is pivotally connected to the turbine and connected to the beam or blade so as to cause torsional twisting thereof in response to centrifugal loading of the pendulum member for turbine speed control purposes.

Abstract: The control system includes a sensing mechanism by which a true pure signal from flapping bending activity resulting from an external load force on a rotor blade in a rotor system is generated and fed back to a gyroscope which then precesses to return a correcting feathering motion to the rotor blade through a swashplate. Such generation is developed by the sensing mechanism which comprises a cantilevered beam or spring system secured at its one end to a fixed hub arm about which the blade feathers and having its other end operatively connected to the gyroscope. The gyroscope is positioned outside of a high force blade feathering loop and is independently sized from the rotor to which it is coupled. The system also provides for pilot command input to produce a control feathering motion to a pair of blades independently of the sensing means.

Abstract: A control system for rotary wing aircraft having a circulation controlled tor is provided. Two axial flow air compressors driven from the engine input shaft provide an air flow which is ducted to the rotor blades through a bifurcated duct and a non-rotating air plenum and released through spanwise slots in the blades. Damping is accomplished by a conically shaped diverter valve in the air plenum and a butterfly valve adjacent the air compressors. Aircraft stability is achieved through a gyro coupled to the rotor shaft which integrates pilot controlled input with rotor cyclic flap moment input.