Showing papers on "Rotation around a fixed axis published in 1977"

Method of and arrangement for controlling manipulators and industrial robots

Abstract: This disclosure is drawn to a method of and an arrangement for controllinghe rotational and translatory motions of a manipulator or industrial robot, which automatically for the entire motion and speed range, even when there is simultaneous movement of a plurality of motion actuators, permit uniform, selectible and disturbance-independent dynamic control properties for individual or all motion parameters. The invention is characterized in that for each rotational or translational motion parameter of the manipulator or industrial robot to be controlled the positioning signal of the associated motion actuator is in part generated by a control means with selectible dynamics. This controller output signal is amplified multiplicatively by the output signal of an arrangement which for a rotational motion reproduces the associated variable moment of inertia and for a translatory motion the associated mass, respectively, inclusive of the variable load mass. The controller output signal is amplified to such an extent that thereby the effect of the variable moment of inertia or of the variable mass is compensated. The other part of the positioning signal of the associated motion actuator is supplied additively by the output of a further compensation arrangement which reproduces the dynamic intercouplings with the other motion variables so that the interference effect upon simultaneously varying a plurality of motion variables is eliminated.

Wind collecting method and apparatus

Abstract: An improved wind collecting apparatus utilized for transforming wind energy to rotary motion. The rotary motion is then used to drive an electric generator or the like. The apparatus generally comprises four semi-cylindrically shaped wind collecting blades connected to a shaft which is mounted for rotation about an axis of rotation and wind deflectors are positioned near the blades for directing portions of the wind. In one embodiment, the shaft is disposed in a plane substantially parallel with the earth's surface and, in one other aspect, the blades are mounted for rotation generally above a cavity formed in the earth's surface. The present invention also contemplates an improved blade structure.

Vibrating machine suspension

Abstract: A vibrating machine, such as an oscillating conveyor, vibratory feeder, or vibratory screen, is mounted to a plurality of supports by a suspension that isolates machine vibrations from the supports. The suspension includes a plurality of U-shaped stirrups extending transversely beneath the machine at intervals spaced longitudinally of the machine. Each U-shaped stirrup extends between a pair of opposed supports to which the stirrup is mounted for pivotal movement about an axis of rotation that extends transversely of the vibrating machine. This axis of rotation is along or near the axis of the instantaneous center of rotation of the stirrup. The stirrups support the vibrating machine at surfaces spaced below the axis of rotation. These stirrup surfaces are located to intersect an axis passing through the region of the center of percussion of the stirrup about the axis of rotation. Vibrations in a direction longitudinal of the vibrating machine impart a rotational motion to each stirrup. Thus, such vibrations are not transmitted to the supports. In a preferred embodiment, resilient bushings are fitted within the U-shaped stirrups coaxial with their axis of rotation, and vibration dampening resilient means are provided for mounting the vibrating machine upon the stirrups.

Molecular dynamics of the rough sphere fluid. III. The dependence of translational and rotational motion on particle roughness

Abstract: Molecular dynamics studies of two generalized forms of the rough sphere model are reported. The generalization permits us to vary the coupling between rotational and translational motion through a stick parameter λ. The autocorrelation functions show deviations from the Enskog theory for all values of λ studied—indicating that collective effects are involved. It appears that the angular velocity correlation function is the sum of two exponentials. A simulation of a mixture of disparate sized rough spheres was also performed. It is found that the rotational motion of the small particle is not significantly altered upon introduction of the large particles, but the linear velocity correlation function of the small particle differes considerably from that of the neat fluid (in the time regime from 5–15 mean collision time units).

Plasma rotation during implosion in a θ pinch

Abstract: A differential rotation of a collisionless theta-pinch column during implosion has been observed and explained by a model in which the driving mechanism is the off-diagonal element p/sub r theta/of the pressure tensor. Rotational motion was detected by directional probes and spectroscopic techniques. Experimental data were modeled by a one-dimensional hybride code which included ionization and chrge exchange of protons with neutral H atoms.

Rotary Motion of Molecules about their Short Axis by Dielectric and Splay Viscosity Measurements

Abstract: The connection between the microscopic parameters, i.e. the diffusion constant or rotational relaxation time, and the macroscopic parameters, i.e. the viscosity coefficients is a puzzling question since the discovery of the Einstein-Stokes formula for translational and Debye formula for rotational diffusion motion. The discrepancy between the diffusion coefficients calculated with the help of viscosity data and the directly measured one was about a factor of 5–100 in spite of Perrin1 modification which attempts to take into account the effect of the non-spherical form of the molecules. In spite of the doubts which are always present in such a comparison, it is useful to draw a parallel between the parameters determined from different experiments.

13C Spin-Lattice Relaxation Times in Liquid Crystalline p,p′-Azoxyanisole

Abstract: The 13C spin-lattice relaxation time T1 in the liquid crystalline compound p,p′-azoxyanisole; (PAA; 4,4′-dimethoxyazoxybenzene) was observed in the nematic and isotropic liquid phases. From the obtained T1’s of the ring and the methyl carbons, the anisotropic rotational diffusion constants were determined. It is concluded that the rotational reorientation around the molecular axis is faster by an order of 103 than the rotational motion around the axis perpendicular to the molecular axis in the nematic and isotropic liquid states.

Device for oscillating a rotating body along its rotational axis

Abstract: A rotating body, such as a pulley or a guide wheel, is oscillatable along its rotational axis. The rotating body is carried by a longitudinal support having a cam surface extending generally perpendicular to the rotational axis. The support is mounted for rotation with a supporting shaft and is biased along the rotational axis so that the cam surface engages a stationary cam follower. Rotation of the shaft, support, and body relative to the cam follower results in the oscillation of the rotatable body.

Nonlinear vector product to describe rotations

Abstract: A method is developed for treating successive rotations in terms of nonlinear products of rotation vectors. Combinations of ordinary scalar and vector products yield the same results that may be more commonly arrived at by the use of quaternions or 2×2 unitary matrices. The method automatically provides the direction of the axis and the value of the rotation angle of the single rotation that is equivalent to the product of two or more successive rotations. This information is not readily obtained from the usual matrix rotation method of solving the successive rotation problem. The method is applied to the case of a rotation about the [1 1 1] direction, successive π rotations about orthogonal axes, and the treatment of continuous rotations.

Waveepower electric generator with a shaft

Abstract: PURPOSE:The wave-power electric generation with a low cost and large output which converts a translational motion of wave to a mechanical rotational motion.

The molecular motion in the solid phases of t‐butyl chloride by cold neutron scattering

Abstract: Cold neutron scattering experiments have been performed on tertiary butyl chloride at the temperature 173 °K in phase III, 205 °K in phase II, and 235 °K in phase I. The crystal is plastic in phases I and II and ordinary crystalline in phase III. The experimental data are interpreted by fitting of computer calculated cross sections, based on various physical models. The main aim was to study the rotational motion. By use of the data from the phase III a reasonalbe Debye form for the translational spectrum is obtained and used also in phases II and I. Similarly the rather well separated torsional spectrum of the methyl groups is simply approximated. The rotational spectra dominate the elastic and near elastic scattering. Models ranging from free rotation to undamped libration, including isotropic Langevin rotational diffusion as an intermediate case when the rotational relaxation times are short, are tested. It is found, that no extreme model corresponding either to almost free rotation, or to almost undam...

Note on buble motion in a rotating liquid under residual gravity

Abstract: The motion of a small gas bubble, presumed to retain its geometrical shape and contained in a rotating liquid, has been investigated. The fluid system liquid-gas is subject to the influence of a reduced gravitational field. It is demonstrated that under certain conditions (spin axis and direction of gravity are perpendicular to each other) the bubble travels on a circular path about the axis of rotation, as seen from an observer moving with the bulk of the liquid.

Dynamic Critical Switching Curve for Uniform Rotational High Speed Switching in Magnetic Thin Films

Abstract: Dynamic threshold fields for the idealized uniform rotational switching in thin films are studied on the basis of the numerical solutions of the Landau-Lifshitz-Gilbert equation of motion. Dynamic critical switching curves deduced from the numerical solutions calculated up to the near equilibrium state are quite different from the usual critical switching asteroid. A part of am irreversible rotation region associated with the present dynamic switching curve is found to enter into the reversible rotation region associated with the usual critical switching asteroid. This curious aspect of the dynamic critical switching curve is well understood by the dynamic consideration in which the kinetic energy and the energy dissipation in a rotational motion of the magnetization are taken into account. The present dynamic treatment is necessary only when the rising time of a driving field is less than 1 ns.