Angular displacement

About: Angular displacement is a research topic. Over the lifetime, 5102 publications have been published within this topic receiving 46081 citations. The topic is also known as: rotational displacement.

Vibration suppression of multi-modal translational motion using a rotational actuator

Abstract: In recent the work of Wan et al. it was shown that a rotational torque actuator with attached eccentric mass can be used to globally stabilize a one-mode translational oscillator. A family of globally stabilizing nonlinear feedback control laws was derived by using partial feedback linearization and integrator backstepping. These control laws accounted for the strongly nonlinear coupling between the rotational motion of the eccentric mass and the translational motion of the oscillator. In the present paper, we extend these results to address the problem of stabilizing the translational motion of multi-mode systems with a rotational actuator. The controller synthesis methodology extends the previous work to address a system involving six state variables. Detailed numerical simulation of the closed-loop system illustrates the angular position of the eccentric mass and the harmonic content of its motion in suppressing both modal frequencies. >

A Trajectory Preprocessor for Antenna Pointing

Abstract: A trajectory-preprocessing algorithm has been devised which matches antenna angular position, velocity, and acceleration to those of a target This eliminates vibrations of the antenna structure caused by discontinuities in velocity and acceleration commands, and improves antenna-pointing performance by constraining antenna motion to a linear regime The algorithm permits faster acquisition times and preserves antenna-tracking capability in situations where there would otherwise be an unacceptably sudden change in antenna velocity or acceleration A simulation of DSS 13 shows that this preprocessor would reduce servo error to 1 mdeg during acquisition of a low-Earth-orbiting satellite

A Novel System for Correction of Relative Angular Displacement between Airborne Platform and UAV in Target Localization

Abstract: This paper provides a system and method for correction of relative angular displacements between an Unmanned Aerial Vehicle (UAV) and its onboard strap-down photoelectric platform to improve localization accuracy. Because the angular displacements have an influence on the final accuracy, by attaching a measuring system to the platform, the texture image of platform base bulkhead can be collected in a real-time manner. Through the image registration, the displacement vector of the platform relative to its bulkhead can be calculated to further determine angular displacements. After being decomposed and superposed on the three attitude angles of the UAV, the angular displacements can reduce the coordinate transformation errors and thus improve the localization accuracy. Even a simple kind of method can improve the localization accuracy by 14.3%.

Rotational digital subtraction angiography phantom

Abstract: A gantry (18) that carries an x-ray source (14) and an x-ray detector (16) rotates around a test phantom (10) in a forward direction. A plurality of forward projection images are generated and stored in a forward image memory (42). The angle at which each forward direction projection image is generated is stored in a position memory (56). The gantry is then rotated in a reverse direction and a reverse direction image is generated at generally the same angular positions as in the forward rotation direction. The forward and reverse direction projection images of the phantom are analyzed to determine an offset or error between each corresponding forward and reverse angular image position. The offsets are stored in an angular position look-up table (80) and a pixel reregistration look-up table (82). In subsequent reverse scans, the angular position at which the reverse direction projection images are taken are altered in accordance with the angular offset for the corresponding angular position. The forward sweep images are video pixel position shifted in accordance with the video pixel offset for the corresponding angular position to bring the forward and reverse direction projection images into registration.

Mechanized trowel for finishing concrete slabs

Abstract: A mechanized trowel including a center body of an elongated configuration supported for rotational displacement about its longitudinal axis and having a helical troweling blade extending along the surface thereof adapted to engage, spread and trowel a body of cement in its plastic state, a supporting rail extended in parallelism with the center body supporting the center body for linear displacement therealong, and a truck supporting the end of the rail for translational displacement about a further axis perpendicularly related to the longitudinal axis of the center body and passing through the end thereof opposite the truck, and reversible, electrically energizable motors connected in driving relation with the center body for imparting thereto rotational, linear and translational displacement.