Showing papers on "Kinematics published in 1971"

Kinematic Analysis of Spatial Mechanisms by Means of Screw Coordinates. Part 2—Analysis of Spatial Mechanisms

Abstract: The basic concepts of screw coordinates described in Part I are applied to the numerical kinematic analysis of spatial mechanisms. The techniques are illustrated with reference to the displacement, velocity, and static-force-and-torque analysis of a general, single-degree-of-freedom spatial mechanism: a seven-link mechanism with screw pairs (H)7 . By specialization the associated computer program is capable of analyzing many other single-loop spatial mechanisms. Numerical examples illustrate the results.

Stable Member Equations of Motion for a Three-Axis Gyro Stabilized Platform

Abstract: This paper presents a detailed development of the equations of motion for the stable member of a three-axis platform. Kinematic relations are presented for an x, z, y Euler sequence. This development includes the effects of friction, inertia, and torque motors. A set of six first-order differential equations of state are presented representing the equations of motion of the system members. These equations may be integrated and the resulting Euler angles and rates used to describe the stable member motions. When combined with the servo loops, the motion of the stable member represents the angular motion environment of the stable member mounted instruments.

An analysis of kinematic vertical motions

Abstract: Several techniques exist for computing vertical motions. In this paper, radiosonde wind observations are used to compute vertical motions by the kinematic method. The presence of cumulative bias errors necessitates adjustment techniques. Simple tests of two techniques indicate that, for the period of this study, a divergence adjustment that is a function of pressure yields the best adjusted vertical motion fields. Further analysis shows that the adjusted estimates correlate well with observed synoptic features. Finally, comparison with estimates by the numerical method indicates that adjusted kinematic vertical motion fields are comparable.

Magnetic-kinematic precision stages

Abstract: The application deals with a magnetic-kinematic precision stage system. The essence is, that stages with linear or angular movement are composed of at least two plates, which move with respect to each others on ball joints. The two plates are held together with retaining magnets. This solution garanties the complete elimination of the backlash. The plates may move very freely, practically without force, with respect to each other. Because practically there is no force, as consequent there is very low friction, and thus adjustement with the greatest precision is possible.

Vehicle engine fuel control accelerator override

Abstract: Apparatus for controlling the position of an accelerator control element of a vehicular engine when the mechanism conventionally employed for moving the same has frozen. The apparatus includes a resilient member in a first kinematic train between said element and the accelerator pedal or like element usually employed by the vehicle operator to regulate the engine speed. The resilient member is connected to said element directly or through nonfreezable components. A return resilient means which is substantially weaker than the resilient member biases the accelerator control element to an idle position. A second kinematic train is so arranged that when actuated by the vehicle operator it will positively move the accelerator control element toward its idling speed operating position. In normal use a force is applied through the first kinematic train and resilient member to move the accelerator control element in an engine speed-up direction while storing up energy in the return resilient means whereby as such force is reduced the engine speed will slow down. If the control element or any part of the first kinematic train is frozen the operator can, through the second kinematic train move the control element against the bias of the resilient member toward its idling speed operating position and in this manner either slow down the engine to idling speed or regulate it to any speed between idling and the speed corresponding to engine speed at which the first kinematic train was frozen. The resilient member is weak enough to be elastically deformed by the force applied by an operator through the second kinematic train.

Interactive linkage synthesis on a small computer

Abstract: An interactive computer program for the kinematic synthesis of motion or function generating linkages is described. The system has been implemented on an 8K IBM 1130 with a storage tube display and a custom-built “globe” graphical input device. The desired performance of the mechanism at four or five prescribed finitely separated positions is specified to the computer, as is the geometry of the fixed and moving bodies. Graphical input devices, or a keyboard, or cards can be used for this purpose. Interactive graphics capability allows input, modification, and display of a complex moving body and fixed frame. Burmester circlepoint-centerpoint curves or Burmester point pairs are displayed for the specified motion, together with a number of other options such as relative poles of rotation. A dynamic cursor which traverses the circlepoint-centerpoint curves allows selection of input and output links of either a four-bar linkage, a slider-crank mechanism, or a turning-block mechanism capable of satisfying the prescribed input criteria. A flashing display aids in selection of circlepoint-centerpoint pairs by indicating the type of linkage that would result from choice of the link being displayed at that instant Grashof's criteria are used to determine whether such a choice would result in a drag link, double rocker, or crank rocker mechanism. Similar criteria have been developed for the slider and turning block equivalents of these mechanisms. The selected linkage can then be animated on the display screen. Continous display of its transmission angle is optional. Examples are given of the practical use of the program.

Paths by Coupler for Kinetic Art

Abstract: The Lumidyne system developed by Malina for kinetic art employs the circular motion of a Rotor or disk to provide real motion of points or areas. This article discusses a simple mechanical assembly for producing with a Coupler plane non-circular paths of an infinite variety that are traversed at varying rates, although the drive is by constant-speed motor. The assembly controlling the motion of the Coupler is called in kinematics a crank-rocker four-bar linkage.