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.

A 3D optical profilometer using a compact disc reading head

Abstract: The design, construction and performance of a novel optical profilometer based on the laser reading head of a compact disc player is described. The instrument is capable of self-guided scanning along arbitrary contours by utilizing the focus and radial tracking signals from the sensor head. The sensor is mounted on an x, y, motorized stage. The radial tracking signal provides the feedback for the angular position of the sensor, ensuring that the optical axis of the sensor is always perpendicular to the profile preventing the signal loss that occurs in conventional profilometers due to deflection of the light beam. The focus signal has a sensitivity in the nanometre range which makes the precision of the stages used to perform the scanning movements the dominant limiting factor for the measuring accuracy. The sensor head intermittently follows the contour, collecting datapoints at a predetermined lateral resolution. The profile is digitized in the form of x, y, and coordinates for each scanpoint. The accuracy of the instrument was verified by scanning standard measures with flat and circular cross sections. The mechanical structure of the prototype instrument was purpose built for the measurement of rigid corneal contact lenses. Various lenses have been measured and profile graphs are illustrated.

Coordinate measurement and radar device using image scanner

Abstract: A system for measuring angles, including a lens or antenna for focusing the radiation from an object scene onto an image sensor which is shifted by a clock, thereby producing the real time imaging of the object scene wherein each element of the object scene is detected as a pulse, representing the element angular displacement from the lens, at the output of the image sensor. A system for measuring angles of objects relative to the centerline of a lens or antenna. A goniometer for measuring the bearing of objects. A system for measuring the vector speed of objects. A velocity meter for measuring the speed of objects. A system for tracking objects. A system for motion compensation. A search, track or track-while-scan detection system. Without the lens or antenna, a system for recording and reproducing halograms.

Dynamics analysis and characteristics of the 8-PSS flexible redundant parallel manipulator

Abstract: The modeling methodology and the dynamic characteristics of the 8-PSS flexible redundant parallel manipulator are investigated based on some basic assumptions. Firstly, the system description and the rigid dynamic model are presented. The actuating forces with minimum norm and least quadratic sum among the possible actuating forces are achieved. Then, the kineto-elastodynamic model of the manipulator is developed by virtue of the finite element method and the substructure synthesis technique. Finally, the dynamic characteristics represented by the natural frequency, the sensitivity analysis, the energy ratios and the displacement responses of the moving platform are investigated through simulation. It is shown that the second order natural frequency is a little higher than the first order natural frequency for the 8-PSS flexible redundant parallel manipulator. The first order natural frequency is much more sensitive to the radius of the lead-screws than to the radius of the struts. From the computation of the energy ratio distribution, the mass of the moving platform should be reduced or the stiffness of the strut should be increased in order to improve the dynamic characteristic of the manipulator. For the investigated trajectory, the displacement response of the moving platform along the x direction is slightly larger than these displacement responses along the y direction and along the z direction. The angular displacement response of the moving platform rotating about the x axis is slightly larger than those angular displacement responses rotating about the y axis and about the z axis.

Laser-speckle angular-displacement sensor: theoretical and experimental study

Abstract: A novel, to our knowledge, method for the measurement of angular displacement for arbitrarily shaped objects is presented in which the angular displacement is perpendicular to the optical axis. The method is based on Fourier-transforming the scattered field from a single laser beam that illuminates the target. The angular distribution of the light field at the target is linearly mapped on a linear image sensor placed in the Fourier plane. Measuring this displacement facilitates the determination of the angular displacement of the target. It is demonstrated both theoretically and experimentally that the angular-displacement sensor is insensitive to object shape and target distance if the linear image sensor is placed in the Fourier plane. A straightforward procedure for positioning the image sensor in the Fourier plane is presented. Any transverse or longitudinal movement of the target will give rise to partial speckle decorrelation, but it will not affect the angular measurement. Furthermore, any change in the illuminating wavelength will not affect the angular measurements. Theoretically and experimentally it is shown that the method has a resolution of 0.3 mdeg (≈5 μrad) for small angular displacements, and methods for further improvement in resolution is discussed. No special surface treatment is required for surfaces giving rise to fully developed speckle. The effect of partially developed speckle is considered both theoretically and experimentally.