Showing papers on "Angular velocity published in 1986"

Inertial mouse system

Abstract: A hand-held inertial mouse provides input data to a computer from which the computer can determine the translational and angular displacement of the mouse. The mouse includes accelerometers for producing output signals of magnitudes proportional to the translational acceleration of the mouse in three non-parallel directions. Pairs of these accelerometers are positioned to detect acceleration along each axis of a cartesian coordinate system such that an angular acceleration of the mouse about any axis of rotation causes representative differences in the magnitudes of the output signals of one or more of these accelerometer pairs. The translational velocity and displacement of the mouse is determined by integrating the accelerometer output signals and the angular velocity and displacement of the mouse is determined by integrating the difference between the output signals of the accelerometer pairs.

Experimental study of convective structures in rotating fluids

Abstract: We describe a series of laboratory experiments to study convective structures in rotating fluids (distilled water) in ranges of Rayleigh flux number Raf from 106 to 2 × 1011 and of Taylor number Ta from 106 to 1012. An intermediate quasi-stationary ring pattern of convection was found to arise from the interaction of the onset of convection with the fluid spin-up, for which we determined the times of origin and destruction, the distances between the rings, and the diameter of the central ring in terms of Raf and Ta. The ring structure evolves into a vortex grid which can be regular or irregular. In terms of Raf and Ta the regular grid exists in the linear regime, when the number of vortices N is in accord with the linear theory, when , or in the nonlinear regime when N ∝ h−2Ta½Raf−⅙ ∝ where Ω is the angular velocity and h is the fluid depth. In the irregular regime we always have N ∝ Ω. The transition from the regular regime to the irregular one is rather gradual and is determined by the value of the ordinary Rayleigh number, which we found to be greater than the first critical number Ra ∝ Ta2/3 by a factor about 25–40. In the transition region vortex interactions are observed, which start with rotation of two adjacent vortices around a common axis, then the vortices come closer and rotation accelerates, following which the vortices form a double helix and then coalesce into one stronger vortex.Some other qualitative experiments show that if the rotating vessel with the convective fluid is inclined to the horizontal, the vortex grid is formed along the rotation axis in accordance with the Proudman–Taylor theorem.

A model of the nystagmus induced by off vertical axis rotation

Abstract: A three-dimensional model is proposed that accounts for a number of phenomena attributed to the otoliths. It is constructed by extending and modifying a model of vestibular velocity storage. It is proposed that the otolith information about the orientation of the head to gravity changes the time constant of vestibular responses by modulating the gain of the velocity storage feedback loop. It is further proposed that the otolith signals, such as those that generate L-nystagmus (linear acceleration induced nystagmus), are partially coupled to the vestibular system via the velocity storage integrator. The combination of these two hypotheses suggests that a vestibular neural mechanism exists that performs correlation in the mathematical sense which is multiplication followed by integration. The multiplication is performed by the otolith modulation of the velocity storage feedback loop gain and the integration is performed by the velocity storage mechanism itself. Correlation allows calculation of the degree to which two signals are related and in this context provides a simple method of determining head angular velocity from the components of linear acceleration induced by off-vertical axis rotation. Correlation accounts for the otolith supplementation of the VOR and the sustained nystagmus generated by off-vertical axis rotation. The model also predicts the cross-coupling of horizontal and vertical optokinetic after nystagmus that occurs in head-lateral positions and the reported effects of tilt on vestibular responses.

Flight Performance and Visual Control of Flight of the Free-Flying Housefly (Musca Domestica L.) III. Interactions Between Angular Movement Induced by Wide- and Smallfield Stimuli

Abstract: The flights of free-flying houseflies are analysed in different behavioural and environmental situations. The angular movements about the vertical body axis are characterized by a cascade of steplike changes of long axis orientation (`turns'). Most of these turns are separated by periods of little or no rotation. Turns about the vertical axis are short (under 120 ms). They are performed at angular velocities of up to about 4000 deg s^(-1). These characteristics are found (i) when a single fly cruises in a stationary environment; (ii) if the visual input is eliminated; (iii) if a textured surround (optomotor stimulus) is moved around the fly; (iv) during visually guided pursuit of small targets in stationary as well as in moving environments. Optomotor stimulation increases the number of turns in the direction of pattern motion relative to those against it. This leads to a correlation between the average angular velocity of the fly and the stimulus velocity. However, optomotor stimulation does not interfere with chasing and tracking. A model is proposed that qualitatively accounts for the observed behaviour in free flight of houseflies.

The computation of structure from fixed-axis motion: Rigid structures

Abstract: We show that an assumption of rigidity or quasi-rigidity is not necessary, in principle, for the computation of three-dimensional structure and motion from changing retinal images. In particular, we show that the three-dimensional structure of certain nonrigid objects, namely objects whose texture elements rotate about a common axis but at varying angular velocities, can in principle be computed from three successive retinal images of four texture elements, or from four successive images of two texture elements. We then show that in both cases the computed structure matches the actual structure of the object with probability one.

Angular velocity and acceleration sensor

Abstract: The specification discloses an angular velocity and acceleration sensor in which a tuning-fork oscillator is vibrated on the main driven vibrating axis and displacement on an axis which is parallel to the main driven vibrating axis or displacement which crosses it at right angles is detected so that at least one of angular velocity and acceleration on an axis which is parallel to the main driven vibrating axis or which crosses it at right angles may be detected. The sensor is characterized in that vibrating reeds of the tuning-fork oscillator are so formed that the spring constant of the vibrating reeds on the main driven vibrating axis is substantially equal to that on the axis which crosses the main driven vibrating axis at right angles.

Bifurcations in Couette flow between almost corotating cylinders

Abstract: Transition to turbulence in a circular Couette system is followed numerically up to the state beyond the second bifurcation in the limit of the narrow gap between coaxial cylinders which rotate with almost equal speeds in the same direction. Taylor-vortex flow, which emerges after the Taylor number T exceeds its critical value Tc = 1708, becomes unstable to two different types of non-axisymmetric disturbances, depending on [Rscr ] (the Reynolds number) and Ω, which measure the velocity difference between the cylinders and the mean angular velocity respectively. Finite-amplitude calculations show that one part of the bifurcating flow is characterized by the vortices winding out of phase in the axial direction but still keeping the boundaries between vortices unaffected. The other is distinguished by the vortex dislocation. The inflow as well as the outflow boundaries between vortices are wavy. Both types of solutions are stationary in the frame of reference rotating with the angular velocity Ω.

Elastic Robot Control: Nonlinear Inversion and Linear Stabilization

Abstract: An approach to the control of elastic robot systems for space applications using inversion, servocompensation, and feedback stabilization is presented. For simplicity, a robot arm (PUMA type) with three rotational joints is considered. The third link is assumed to be elastic. Using an inversion algorithm, a nonlinear decoupling control law Ud is derived such that in the closed-loop system independent control of joint angles by the three joint torquers is accomplished. For the stabilization of elastic oscillations, a linear feedback torquer control law us is obtained applying linear quadratic optimization to the linearized arm model augmented with a servocompensator about the terminal state. Simulation results show that in spite of uncertainties in the payload and vehicle angular velocity, good joint angle control and damping of elastic oscillations are obtained with the torquer control law u = ud + us.

Dynamic flight simulator control system

Abstract: A dynamic flight simulator control system for enhancing flight realism to ailot with regard to his perception and response to the linear forces and angular motions generated by a gimballed force and motion platform at the end of a rotating arm. Flight commands generated by controls identical to those in a specified aircraft and operated by the pilot as if flying are converted to the forces and motions predetermined for the aircraft and translated into simulator command signals which regulate the angular velocity of the arm and the roll and pitch of the platform. The perceived angular motions for both the aircraft pilot and the simulator pilot are predicted by computers pre-programmed with mathematical models of their human angular sensor responses and any difference is minimized by iteratively adjusting coefficients in the simulator command signals for predetermined weighting factors based on the individual pilot's preference.

Belt drive method and apparatus

Abstract: This disclosure relates to a belt-drive method and apparatus wherein the rotational force of a drive shaft is accompanied by minute fluctuations in the angular velocity, and a driven shaft has rotational inertia. A one-way clutch is provided in the belt drive, which forms a selective interruption of the rotational force transmission through the belt drive while the angular velocity at the drive shaft side is decelerating, the force being transmitted only while the angular velocity is increasing.

System for controlling motion of a robot

Abstract: In a system for controlling the motion of an industrial robot, a resultant translational velocity of a preselected point on the robot is calculated from a plurality of velocity values such as actual velocity values detected by sensors or target velocity values computed from a velocity reference value. Upon the exceeding of a predetermined maximum velocity by the calculated resultant velocity, all robot motion is terminated. Robot motion may also be stopped upon detecting an excessive difference between an actual angular velocity of one robot component and a respective desired or target angular velocity of that robot component, upon detecting an excessive translational acceleration of a predetermined point on the robot, or upon detecting a position of the robot part or point located more than a predetermined distance from a reference position.

Method and apparatus for trelemetry while drilling by changing drill string rotation angle or speed

Abstract: The cyclic angular dependence of the output of gravitational inclinometers and magnetometers is used to communicate from the well surface to a microprocessor downhole. The microprocessor controls an arbitrary downhole function. Information is communicated to the microprocessor via the inclinometer and magnetometer by selectively rotating the drill string during a data time interval through a predetermined magnitude of angular displacement or angular velocity. Each additional multiple of angular displacement or angular velocity is interpreted as a distinguishable unit of information. A command word is assembled from a sequential plurality of units of information in the microprocessor and a downhole function is executed according to the command word.

Turbulent transport of angular momentum and differential rotation

Abstract: With the help of simplifying approximations, we have derived expressions for the non-diffusive fluxes of the angular momentum which are brought about by the action of Coriolis forces on the convective motion. The original turbulence, which is not perturbed by the Coriolis forces, is considered given and weakly anisotropic, the anisotropy having a preferred radial direction. The eddy viscosities are evaluated. Hence, a closed equation for the angular velocity is derived, and then solved for the case of slow rotation. It is shown that the differential rotation is generated most effectively in the case of moderate rotation when the Rossby number is of order unity. At small Rossby numbers, the rotation differentiality is inhibited. A negative eddy viscosity is suggested for the case of rapid rotation. Some implications for the Sun and other astrophysical objects are discussed.

A mass shell with flat interior cannot rotate rigidly

Abstract: Previous work on approximate solutions for rotating mass shells with flat interior is extended to third order in the angular velocity omega . It is shown that the condition of flatness can only be preserved in this order if the mass shell exhibits differential rotation. The first-order result, that a compact rotating mass shell with M=2R creates total dragging of the inertial frames inside the shell, is not invalidated by third-order corrections. By analysing the structure of the solutions in arbitrary order of omega , it is proven that there exists exactly one solution for a rotating mass shell with flat interior.

Hydromagnetic Stokes flow in a rotating fluid with suspended small particles

Abstract: An initial value investigation is made of the motion of an incompressible, viscous conducting fluid with embedded small spherical particles bounded by an infinite rigid non-conducting plate. Both the plate and the fluid are in a state of solid body rotation with constant angular velocity about an axis normal to the plate. The flow is generated in the fluid-particle system due to non-torsional oscillations of a given frequency superimposed on the plate in the presence of a transverse magnetic field. The operational method is used to derive exact solutions for the fluid and the particle velocities, and the wall shear stress. The small and the large time behaviour of the solutions is discussed in some detail. The ultimate steady-state solutions and the structure of the associated boundary layers are determined with physical implications. It is shown that rotation and magnetic field affect the motion of the fluid relatively earlier than that of the particles when the time is small. The motion for large times is set up through inertial oscillations of frequency equal to twice the angular velocity of rotation. The ultimate boundary layers are established through inertial oscillations. The shear stress at the plate is calculated for all values of the frequency parameter. The small and large-time behaviour of the shear stress is discussed. The exact solutions for the velocity of fluid and the wall shear stress are evaluated numerically for the case of an impulsively moved plate. It is found that the drag and the lateral stress on the plate fluctuate during the non-equilibrium process of relaxation if the rotation is large. The present analysis is very general in the sense that many known results in various configurations are found to follow as special cases.

Jet engine testing apparatus

Abstract: An apparatus for detecting jet engine failures during aircraft flight. Low and high speed rotor rotation velocities of one engine are compared with low and high rotor rotation velocities of other engines and the difference between them utilized to determine engine failure. Equivalent low speed rotor velocity of an engine is computed from the high speed rotor velocity of that signal. This computed value is compared with measured low speed rotor velocity of the same and of different engines. Differences between the computed values and the actual values are compared to a computed threshold, which allows for normal differences between engines, to determine the operational state of the engine. Additional engine testing is performed by comparing low speed rotor rotational velocity to a computer windmilling value for each engine.

Active damping of satellite nutation

Abstract: For controlling nutation of a three-axis stabilized satellite, the angular speed of a solar panel carried by the satellite is selectively and temporarily varied about an average value for modifying the inertia cross-product thereof and generating an angular momentum transverse to the angular momentum present in said body with a phase with respect to the nutation motion which tends to decrease the amplitude of the nutation motion.

Rotation and Expansion within Sunspot Groups

Abstract: By superposing data for many sunspot groups measured on the Mount Wilson white-light plate collection, we demonstrate that differential rotation, about equal to the ambient rate, occurs between sunspots within the group. We also show that the relative motions of leader and follower sunspots can be characterized primarily as a simple expansion of the group along its major axis, with very little rotation of the pattern about group center. Subject headings: Sun: atmospheric motions — Sun: sunspots

Reorientational motion in liquid MeCN and its relationship to the properties of the intermolecular torques

Abstract: The relaxation of the orientational correlation functions found in a simulation of methyl cyanide (MeCN), which is determined by both ‘tumbling’ of the molecular symmetry axis and the ‘spinning’ about the axis, has been investigated in the cumulant expansion scheme. For the tumbling motion the truncated cumulant expansion may be used to relate the short-time, non-exponential behaviour of the correlation function of an appropriately chosen component of the angular velocity; the physical situation is similar to that which has been found in studies of linear and tetrahedral molecules. The cumulant expansion also permits the separation of correlation functions which reflect only the spinning motion; however the shapes of these functions cannot be described within the scheme, that is they are not completely determined by an angular velocity correlation function. The reasons for this failure are examined and it is shown that the non-gaussian nature of the torques acting about the symmetry axis is having a signi...

Apparatus for the display of high definition images

Abstract: Apparatus for producing high definition projected video images comprising light-emitting means providing in use at least one collimated beam of light, acousto-optic means for modulating said at least one beam of light, means for scanning said at least one beam of light at a substantially constant angular velocity in a plane aligned with the direction of travel of the modulating sound in the acousto-optic means and means for matching optically the angular velocity with respect to the scanning means of the modulating sound in the acousto-­ optic means to the angular velocity of beam scanning of the scanning means so that said modulating sound angular velocity or the angular velocity of an image of the pattern thereof is substantially equal to and aligned with said beam scanning angular velocity and, for a given length of optical path intermediate the position of modulation and the scanning means, the bandwidth of the projected video image is substantially greater in use than the bandwidth achievable with a single channel acousto-optic modulator positioned at the Scophony distance from the scanning means, said Scophony distance being no less than said given length of optical path.

Microwave oven and method with controlled heating profile

Abstract: Microwave oven and method in which the microwave energy pattern and the load are moved relative to each other, and the rate of movement is varied to control the amount of heating in different portions of the load. In some embodiments, a rotator causes the microwave energy pattern to be modulated within the oven cavity. The microwave power at different points in the oven cavity is measured with the rotator in different angular positions, and the angular velocity of the rotator is varied so that the rotator spends more time in angular positions where more heating is required. In other embodiments, the load is rotated, and the angular velocity of the load is varied so that the load spends more time in angular positions where additional heating is required.

Chapter 1: Structure, Distributions and Dynamics of Vortices in Helium II

Abstract: Publisher Summary This chapter focuses on quantized vortices and the various configurations that occur. It discusses the structure of vortices, including the interaction with impurities, and deals with equilibrium vortex distributions, such as are induced by rotation. The chapter focuses on vortex lines, arrays of lines, and rings. It discusses steady state effects: friction on vortices, the interaction of heat flow and rotation in one particular geometry, vortex pinning, spin-up, and vortices in thin films. If helium II is contained in a rotating bucket, it is known experimentally that at low speeds of rotation, the normal fluid rotates with the container and the superfluid remain at rest. At a certain critical angular velocity of rotation, a single quantized vortex line appears in the center of the container. Experiments on helium II suggest that there are residual vortices present upon cooling through the lambda transition.

Angular velocity sensor

Abstract: PURPOSE:To detect with a high accuracy an angular velocity of a rotating body by detecting a magnitude of the angular velocity and a direction of the angular velocity, from a ratio of a detecting signal obtained from a detecting element and a driving signal of the detecting element, and from a phase relation of the detecting signal and the driving signal, respectively CONSTITUTION:A detecting element 1 has a driving part 2 and a detecting part 3, and rotates as one body with a rotating body A driving circuit 4 supplies a driving signal VI to the driving part 2, and vibrates the detecting part 3 A signal VS which is detected 5 in accordance with a Corioli's force from the detecting part, generated thereby is brought to a full-wave rectification 11 through an amplifying circuit 9, and a DC voltage VS3 is outputted An amplitude ratio of the voltage VS3, and a DC voltage VI4 obtained by half-wave-rectifying 10 and smoothing 13 the signal VI is detected by a logarithmic amplifying circuit (LAMP) 17, and on the other hand, as for the signal VI, the frequency is detected by a LAMP 16 An output VI3 of the circuit 17 and an output VL4 of the LAMP 16 are added 18, and the adding part 18 outputs a signal V01 corresponding to a magnitude of an angular velocity of the rotating body On the other hand, a phase of an output VI3 of the half-wave rectifying circuit 10 and an output VS2 of the circuit 9 is detected 14, and a phase detecting circuit 14 outputs a signal VP for showing a direction of an angular velocity

Angular speed sensor and its application to a combined torque and angular speed sensor for a motor vehicle steering column

Abstract: This angular speed sensor comprises two coaxial discs 10, 11 which are electrically insulating and integral in rotation with respective members 1, 3 whose relative angular speed is to be measured. Each disc carries on one of its faces a detection winding consisting of an even number of conducting coils in the form of spiral sectors wound alternately in one direction and the other, and whose mutual inductance varies as a function of the relative angular position of the said discs. The sensor also comprises a supply circuit 16 applying a high-frequency AC voltage to one of the windings, and a circuit 17 for processing the signal collected at the terminals of the other winding. The processing circuit 17 is a demodulator which converts the said signal, which is amplitude-modulated, into an output signal with frequency directly proportional to the relative angular speed of the said members 1, 3. Application to measuring the angular speed of a steering shaft.