Linear motion

Abstract: Two-dimensional image motion is the projection of the three-dimensional motion of objects, relative to a visual sensor, onto its image plane. Sequences of time-orderedimages allow the estimation of projected two-dimensional image motion as either instantaneous image velocities or discrete image displacements. These are usually called the optical flow field or the image velocity field. Provided that optical flow is a reliable approximation to two-dimensional image motion, it may then be used to recover the three-dimensional motion of the visual sensor (to within a scale factor) and the three-dimensional surface structure (shape or relative depth) through assumptions concerning the structure of the optical flow field, the three-dimensional environment, and the motion of the sensor. Optical flow may also be used to perform motion detection, object segmentation, time-to-collision and focus of expansion calculations, motion compensated encoding, and stereo disparity measurement. We investigate the computation of optical flow in this survey: widely known methods for estimating optical flow are classified and examined by scrutinizing the hypothesis and assumptions they use. The survey concludes with a discussion of current research issues.

Abstract: This invention relates to a coordinate sensor for detecting the position of a moveable detector relative to a data space coded with coordinate information by detecting and processing the coordinate information. It may be used for obtaining both two and three dimensional position related information, such as might be used for determining the position of a pen/pencil on paper for handwriting data input. It also may be used for detecting angular, rotational, and linear motion. The coordinate sensor provides an apparatus for precisely locating the position of a movable element within a space. More particularly, it provides an input/output apparatus for use with a computer that includes a movable element, whose exact position within a space can be determined without any physical connection between the movable element and the space. It comprises a data space formatted with a code for designating the coordinates of a point in the data space, a detector for detecting the code, a processor for processing data from the detector to determine the position of the point in the data space, and a data output method for human interface to the coordinate sensor.

Abstract: The equations of motion of a 180° domain wall in an infinite uniaxially anisotropic medium which is exposed to an instantaneously applied uniform dc magnetic field H0 have been integrated numerically. Below the critical field Hc =2παM0 (α is the Gilbert loss parameter and M0 the saturation magnetization), where a steady‐state solution is known to exist, it is shown that the wall motion tends smoothly to this solution. Above Hc, the magnetization precesses about the field and a periodic component appears in the forward motion of the wall. Analytic solutions for the wall motion have been found based upon approximations suggested by the computed behavior; these reproduce the computer results very accurately.

Abstract: A surgical instrument and method of controlling the surgical instrument are disclosed. The surgical instrument includes a housing and an elongated shaft that extends distally from the housing and defines a first longitudinal axis. The surgical instrument also includes a firing rod disposed in the elongated shaft and a drive mechanism disposed at least partially within the housing. The drive mechanism mechanically cooperates with the firing rod to move the firing rod. A motion sensor senses a change in the electric field (e.g., capacitance, impedance, or admittance) between the firing rod and the elongated shaft. The measurement unit determines a parameter of the motion of the firing rod, such as the position, speed, and direction of the firing rod, based on the sensed change in the electric field. A controller uses the measured parameter of the motion of the firing rod to control the drive mechanism.