401results about "Aircraft stabilisation by gravity apparatus" patented technology

A stabilization system including a platform supported by two or more rotatably-coupled gimbal frames each having a pivot assembly disposed at its rotation axis to couple an actuator to a rotation sensor having a rotation-sensitive sensor axis that is fixedly disposed with respect to the rotation axis, and a controller including means for accepting the sensor signals and for producing each motor signal needed to dispose the platform in a predetermined angular position with respect to each rotation axis independent of changes in the base orientation. A motion simulator embodiment includes controller means for accepting an external slew signal sequence and means for producing the motor signals needed to move the platform along a predetermined sequence of positions represented by the slew signal sequence.

A guideless stage for aligning a wafer in a microlithography system is disclosed, and a reaction frame is disclosed which isolates both external vibrations as well as vibrations caused by reaction forces from an object stage. In the guideless stage an object stage is disclosed for movement in at least two directions and two separate and independently movable followers move and follow the object stage and cooperating linear force actuators are mounted on the object stage and the followers for positioning the object stage in the first and second directions. The reaction frame is mounted on a base structure independent of the base for the object stage so that the object stage is supported in space independent of the reaction frame. At least one follower is disclosed having a pair of arms which are respectively movable in a pair of parallel planes with the center of gravity of the object stage therebetween. The linear positioning forces of the actuator drive means are mounted and controlled so that the vector sum of the moments of force at the center of gravity of the object stage due to the positioning forces of the drive means is substantially equal to zero. The actuator mounting means can include at least two thin flexible members mounted in series with the primary direction of flex of the members being orthogonal to one another.

A vertical takeoff and landing (VTOL) air vehicle disclosed. The air vehicle can be manned or unmanned. In one embodiment, the air vehicle includes two shrouded propellers, a fuselage and a gyroscopic stabilization disk installed in the fuselage. The gyroscopic stabilization disk can be configured to provide sufficient angular momentum, by sufficient mass and/or sufficient angular velocity, such that the air vehicle is gyroscopically stabilized during various phases of flight. In one embodiment the fuselage is fixedly attached to the shrouded propellers. In another embodiment, the shrouded propellers are pivotably mounted to the fuselage.

A lithographic projection apparatus includes a passive magnetic bearing configured to provide support between a first and second part of the lithographic apparatus and allow both parts to be displaced relative to each other in a direction perpendicular to the support direction. The passive magnetic bearing includes first and second magnetic assemblies. Each magnetic assembly includes at least one permanent magnet.

The universal vehicle system is designed with a lifting body which is composed of a plurality of interconnected modules which are configured to form an aerodynamically viable contour of the lifting body which including a front central module, a rear module, and thrust vectoring modules displaceably connected to the front central module and operatively coupled to respective propulsive mechanisms. The thrust vectoring modules are controlled for dynamical displacement relative to the lifting body (in tilting and/or translating fashion) to direct and actuate the propulsive mechanism(s) as needed for safe and stable operation in various modes of operation and transitioning therebetween in air, water and terrain environments.

An unmanned air vehicle comprises a fuselage that defines aerodynamic flight surfaces, an engine mounted to the fuselage having an engine shaft arranged to rotate about a longitudinal axis with respect to the fuselage, and a propeller mounted to the engine shaft so as to rotate to thereby provide thrust. The aircraft also comprises a gyroscopic stabilization member coupled to the shaft such that rotation of the engine shaft results in rotation of the gyroscopic member. Thus, there is more stability during the entire flight envelope. In one embodiment, the gyroscopic stabilization member is comprised of a ring that is attached to the outer ends of the blades of the propeller and the ring is also selected so as to have a mass that will result in the gyroscopic stabilization member having a sufficient angular momentum so as to gyroscopically stabilize the aircraft.

A system and method are provided for controlling a stepper motor having a rotor and a multi-phase stator. Sinusoidal command signals define a commanded position of the motor's rotor. An actual position of the rotor is sensed as a function of an electrical angle between the actual position and the commanded position. The actual position is defined by sinusoidal position signals. An adjustment signal is generated using the sinusoidal command signals and sinusoidal position signals. The adjustment signal is defined as a function of the cosine of the electrical angle. The adjustment signal is multiplied by each sinusoidal command signal to generate a corresponding set of excitation signals, each of which is applied to a corresponding phase of the multi-phase stator.