Showing papers on "Angular displacement published in 2010"

Rigid Body Dynamics

Abstract: The motion of a rigid body contains two parts: linear motion and angular motion. In this document, we will study both motions. We will also discuss how to detect collisions and estimate collision responses. To simplify our notations, we will follow the standard formats: bold fonts are vectors, italic fonts are scalars, and UPPERCASES are matrices. The physics quantities associated with linear motion are: position, velocity, force, ... The physics quantities associated with angular motion are: orientation, angular velocity, torque, ...

System and method for determining a steering angle for a vehicle and system and method for controlling a vehicle based on same

Abstract: A system for determining an angular position of a pair of steerable wheels of a vehicle having a plurality of wheels can include a yaw rate sensor, a pair of wheel speed sensors and a controller. The yaw rate sensor can be configured to output data representative of an angular velocity of the vehicle about a vertical axis of the vehicle. Each of the pair of wheel speed sensors can be configured to output data representative of a rotational velocity of a respective one of the plurality of wheels. The controller can be in electrical communication with each of the pair of wheel speed sensors and the yaw rate sensor. The controller can be configured to determine a first steering angle based on data received from the yaw rate sensor, to determine a second steering angle based on data received from the plurality of wheel speed sensors, and to select one of the first steering angle and the second steering angle for use in manipulating various vehicle parameters, including torque vectoring parameters, among other parameters.

In-vehicle terminal for control forward looking infrared camera and method thereof

Abstract: PURPOSE: A terminal for a vehicle, for controlling a front monitoring camera and a method thereof are provided to reduce the visual fatigue of a driver by supplying stable image by maintaining the uniform direction of a camera. CONSTITUTION: A terminal for a vehicle comprises an infrared camera(34), an angular displacement calculating unit(49), a rotational degree sensing unit(42), a controller(60), and a driving part(46). The infrared camera gets an image of the front of a vehicle. The angular displacement calculating unit measures the angular velocity to the pitch rotation of the axis, and produces the pitch angle displacement of a gimbal(38). The rotation quantity sensor measures the rotation angle displacement of the infrared camera to the gimbal. The controller outputs the control signal for controlling a sight direction of the infrared camera by using the pitch angle displacement and rotation angle displacement. The driving part makes the infrared camera pitch-pivoting and controls sight directions of the infrared camera.

Passive torque wrench and angular position detection using a single-beam optical trap

Abstract: The recent advent of angular optical trapping techniques has allowed for rotational control and direct torque measurement on biological substrates Here we present a method that increases the versatility and flexibility of these techniques We demonstrate that a single beam with a rapidly rotating linear polarization can be utilized to apply a constant controllable torque to a trapped particle without active feedback, while simultaneously measuring the particle angular position In addition, this device can rapidly switch between a torque wrench and an angular trap These features should make possible torsional measurements across a wide range of biological systems

Conical diffraction of linearly polarised light controls the angular position of a microscopic object.

Abstract: Conical diffraction of linearly polarised light in a biaxial crystal produces a beam with a crescent-shaped intensity profile. Rotation of the plane of polarisation produces the unique effect of spatially moving the crescent-shaped beam around a ring. We use this effect to trap microspheres and white blood cells and to position them at any angular position on the ring. Continuous motion around the circle is also demonstrated. This crescent beam does not require an interferometeric arrangement to form it, nor does it carry optical angular momentum. The ability to spatially locate a beam and an associated trapped object simply by varying the polarisation of light suggests that this optical process should find application in the manipulation and actuation of micro- and nano-scale physical and biological objects.

Identifying the control of physically and perceptually evoked sway responses with coincident visual scene velocities and tilt of the base of support.

Abstract: In this study, we have explored whether the impact of visual information on postural reactions is due to the same perceptual mechanisms that produce vection. Pitch motion of the visual field was presented at varying velocities to eight healthy subjects (29.9 ± 2.8 years) standing quietly on a stationary base of support or receiving a 3° toes-up tilt of the base of support. An infrared motion system recorded markers placed on body segments to record angular displacement of head and ankle and calculate whole body center of mass. Onset of the visual field motion and base of support movement were synchronized in all trials. We found that in the first 2 s following onset of visual field motion, both direction and amplitude of the linear displacement of whole body center of mass and angular displacement of the head, hip, and ankle were modulated by the velocity of visual scene motion. When the visual scene rotated in upward pitch, subjects overshot their initial vertical position with amplitudes that increased as velocity of the visual field increased. This behavior was even more evident when the base of support was tilted. These responses were much shorter than those observed in studies of vection. The dependence of the postural response amplitudes on the velocity of the visual field suggests, however, that there might be well-shared control pathways for visual influences on postural reactions and postural sway elicited by an illusion of self-motion.

High-resolution fibre-optic sensor for angular displacement measurements

Abstract: The design of a fibre-optic sensor able to measure high-precision angular displacements is presented. The sensor has a small size which allows easy integration in miniature mechanical systems. Two configurations are designed: lens-free configuration and GRIN micro-lens configuration for which the micro-lens is fixed on the tip of the probe. The experimental results obtained by the angular displacement sensor based on the lens-free configuration are compared with the simulation results based on the modelling of the system and a good agreement is found. Then, a long-range measurement technique is described. In the 'lens-free and long-range configuration', the limit of resolution is measured (2 × 10−3°) or calculated (4.8 × 10−4°) over a range of [−23.4°, +23.4°]. In the 'GRIN lens and long-range configuration', the best limit of resolution is decreased to 2.2 × 10−4° but over a smaller range of [–14.5°, +14.5°]. Finally, the sensor in its 'lens-free configuration' design is integrated into a miniature electromagnetic actuator to determine its stroke by a comparison of the output signal obtained between this unknown-stroke actuator and a rotating stage for which the stroke was precisely known.

Tracking control for angular-rate-sensorless vertical take-off and landing aircraft in the presence of angular-position measurement delay

Abstract: In this study, the authors address the non-linear tracking problem of a roll-rate-sensorless vertical take-off and landing aircraft in the presence of roll-angle measurement delay. By using the first-order Pade approximation signal of the delayed roll angle, the authors develop an extended attitude observer and a tracking controller based on the observer, two global coordinate transformations and an extension of backstepping technique. Moreover, a finite-time-convergent differentiator is introduced to simplify the computation of one of the control signals. The resulting approximate tracking controller is practicable for actual implementation. Numerical simulations are performed to show the effectiveness of the approximate controller.

Six-degree-of-freedom real-time measuring device of compound motion mechanism

Abstract: The utility model relates to a six-degree-of-freedom real-time measuring device of a compound motion mechanism, which belongs to the technical field of automatic measurement The six-degree-of-freedom real-time measuring device of the compound motion mechanism comprises a controller and a sensor, wherein the sensor is connected with the controller, and the six-degree-of-freedom real-time measuring device is characterized in that the sensor comprises a rotating transformer and a magnetic grid ruler, three angular displacement mechanisms are connected with the rotating transformer, three linear displacement mechanisms are connected with the magnetic grid ruler, the rotating transformer and the magnetic grid ruler are connected with the controller, and the controller is connected with a display The six-degree-of-freedom real-time measuring device has the advantages of simple structure, convenient use, good real-time property, high measurement precision and abundant data treatment interfaces, and can well measure the six-degree-of-freedom displacement, the speed and the like of the compound motion system relative to a geodetic coordinate system

Approximation of finite rigid body motions from velocity fields

Abstract: It is well-known that there is no integrable relation between the twist of a rigid body and its finite motion. Moreover, the reconstruction of the body's motion requires to solve a set of differential equations on the rigid body motion group. This is usually avoided by introducing local parameters (e.g. Euler angles) so that the problem becomes an ordinary differential equation on a vector space (e.g. kinematic Euler equations). In this paper the original problem on the motion group is treated. A family of approximation formulas is presented that allow reconstructing large rigid body motions from a given velocity field up to a desired order, where a k-th order reconstruction requires the first k - 1 time derivatives of the velocity. Such reconstruction formulas could be used whenever the velocity field is accessible. As an example the formulas are applied to the rotation update in a momentum preserving time stepping scheme for the dynamic Euler equations.

Gauge for three directional deformation of ground fissure

Abstract: The invention discloses a gauge for three directional deformation of a ground fissure. The gauge comprises two vertical uprights which are respectively fixed at the left side and the right side of theground fissure, a horizontal tension displacement testing device which is fixed between the two vertical uprights, a vertical displacement testing device and a horizontal shear displacement testing device which are arranged on one of the vertical uprights, a data analysis system and an alarm unit controlled by the data analysis system; the vertical displacement testing device comprises a verticalslide block and a vertical line displacement sensor; the horizontal tension displacement testing device comprises a horizontal support slide shaft, a horizontal support bar, a horizontal slide blockand a horizontal line displacement sensor; the horizontal shear displacement testing device is an angular displacement sensor; and the horizontal line displacement sensor, the vertical line displacement sensor and the angular displacement sensor are connected with the data analysis system. The gauge has the advantages of convenient installation and debugging, convenient use and operation, high testing precision and good testing effect, and can synchronously detect absolute values of three directional deformations at the same point of the ground fissure.

The Melnikov criterion of instability for random rocking dynamics of a rigid block with an attached secondary structure

Abstract: In this paper we investigate the effect of structural flexibility on rocking motion of a system consisting of a free standing rigid block with an attached chain of uniaxially moving point masses. Motion is excited by random acceleration of the ground; instability is associated with overturning of the overall structure. The condition of instability is constructed by the stochastic Melnikov method. We demonstrate a twofold effect of structural flexibility on the rocking response. The attached structure may increase the critical angular displacement and velocity in comparison with the similar parameters of the single rigid block. At the same time, the enlargement of the domain of stability enhances the contribution of the random perturbation in the Melnikov process. As a result, a lower level of random forcing can result in overturning of the structure. As an example, an effect of a single-mass secondary structure on the dynamic behavior of the system is discussed. The paper is restricted to the consideration of seismic vulnerability of the structure. A similar approach can be applied to systems with wind or wave excitation.

Retrospective cost adaptive control of a planar multilink arm with nonminimum-phase zeros

Abstract: We address the problem of adaptive command following and disturbance rejection for a nonlinear planar multilink mechanism interconnected by torsional springs and dashpots. We consider a nonlinear multilink mechanism where a control torque is applied to the hub of the multilink mechanism, and the objective is to control the angular position of the tip, which is separated from the hub by N links. In this paper, we derive the nonlinear equations of motion for the N link mechanism. We linearize these equations of motion and demonstrate that such systems have nonminimum-phase zeros when the control torque and angular position sensor are not colocated. To control this mechanism, we use a retrospective cost adaptive controller, which is effective for nonminimum-phase systems provided that you have an estimate of the nonminimum-phase zeros. We consider both command following and disturbance rejection problems, where the spectrum of the commands and disturbance are unknown.

Angular probe based on using Fabry-Perot etalon and scanning technique

Abstract: A novel angular probe using the Fabry-Perot etalon and angular scanning technique is proposed for absolute angular displacement determinations in this paper. The measurement theory is first derived, a setup constructed to implement the angular probe is then introduced and analyzed, and the experimental results from the uses of the setup are finally presented. The setup analyses reveal that the probe is with high measurement resolution and sensitivity. The experimental results not only confirm the validity, stability, accuracy, and repeatability, but also show an application of the angular probe.

Closed loop control of a rotational joint driven by two antagonistic dielectric elastomer actuators

Abstract: Dielectric elastomers are a subclass of electronic EAPs able to produce large deformations (and thus mechanical work) when an external electric field is applied. While the intrinsic compliance of this kind of polymeric actuators have been always addressed as major benefit with respect to traditional electromagnetic motors, unable to fully capture the capabilities and mechanical properties of biological muscles, their polymeric nature poses peculiar challenges in controlling a system which is subject to nonlinearities, hysteresis and viscous creep behavior. In this paper we explore the controllability properties of a simple rotational joint driven by two dielectric elastomer actuators arranged in an antagonistic configuration. A number of sensors are used to obtain information about the state of controlled system: the angular position of the joint is measured by an angular encoder, custom-designed tension sensors are used to monitor the tension of the two driving tendons and linear encoders provide accurate measurements of the displacements generated by the two actuators. Using this feedback information, a control algorithm has been implemented on a microcontroller unit in order to independently activate the two actuators, allowing a closed loop control of both the angular position of the joint (position control) and the tensions of its tendons (force control). A description of the developed control strategy and its performances under different load conditions are discussed in this paper.

External stability of resonances in the motion of an asymmetric rigid body with a strong magnet in the geomagnetic field

Abstract: We consider a precession motion, close to the classical Lagrange case, of an asymmetric rigid body with a strong magnet in an orbit in the geomagnetic field. For the principal moment we take the restoring torque due to the interaction between the planet magnetic fields and the rigid body. The perturbing actions are due to small moments of the rigid body mass-inertial asymmetry and small constant moments. We show that these perturbations result in the realization of secondary resonance effects in the rotational motion of the rigid body caused by the influence of resonance denominators in higher-order approximations of the averaging method. These effects were discovered in the study of rotational motion of a satellite with a magnetic damper in the nearly Euler case. In the present paper, we analyze both the secondary resonance effects themselves and the external stability of resonances. We obtain conditions ensuring a decrease in the angular velocity of the rigid body rotation about its center of mass. We also discover several new laws of influence of resonances on the nonresonance evolution of slow variables, which is related to the appearance of stable resonances.

Method for detecting reflective liquid level displacement based on angular displacement tracking

Abstract: The invention relates to a method for detecting reflective liquid level displacement based on angular displacement tracking, which comprises the following steps that: a light-emitting device generates a beam of visible light or invisible light through a group of lenses, and the visible light or the invisible light enters a liquid surface at a certain angle alpha to generate reflected light at the same angle; by using the other group of lenses on a receiver, the reflected light is received by a photoelectric conversion device to form images on a detection surface so as to generate electric signals, and the electric signals are treated by a circuit to determine the initial position of the liquid level as shown in a figure; when the liquid level is displaced, the emitting angle of a light beam is changed continuously in a mode of synchronous tracking to form the angular displacement of emitted light, and a light image track proportioned with the liquid level displacement can be generated on a fixed detection surface; and the distance of the liquid level displacement can be acquired according to the angular displacement through circuit and routine calculation according to a trigonometry theory, and if the time when the displacement happens is recorded at the same time, the speed of the liquid level displacement can be obtained. Because the position of the liquid level and the light beam emitting angle have a one-to-one correspondence relation, when the displacement distance is large, the angles of an emitted light beam and a receiving lens can be simultaneously changed to detect the distance and the speed to the liquid level displacement.

System for controlling the angular position of stator blades and method for optimising said angular position

Abstract: A system for controlling angular position of stator blades including: a mechanism for calculating a set angular position of the blades according to one of speeds; and a module for correcting the set position including: a mechanism for determining the angular position of the blades; a mechanism for measuring fuel flow rate of the turbine engine; a memory unit in which consecutive angular positions of the blades are combined with the fuel flow rates of the turbine engine measured at the angular positions; and a mechanism for determining a correcting angle according to the difference between the fuel flow rates measured between two consecutive angular position of the blades. A method for optimizing the common angular position can utilize the system.

Multi-turn sensor

Abstract: A multi-turn angular position sensor a main gear configured to couple to and rotate, in response to rotation of a rotation member, over a main gear rotation range, a first sensor gear engaged with the main gear and configured to experience more angular rotation than the main gear in response to rotation of the main gear, and a second sensor gear engaged with the main gear and configured to experience more angular rotation than the main gear and less angular rotation than the first sensor gear in response to rotation of the main gear. The angular position sensor also includes a first angular position sensor configured to sense rotation of the first sensor gear and to generate a first output signal indicative of rotation of the first sensor gear, and a second angular position sensor configured to sense rotation of the second sensor gear and to generate a second output signal indicative of rotation of the second sensor gear. The main gear and the first and second sensor gears are configured such that a difference in a number of 360 degree revolutions experienced by the first sensor gear and the second sensor gear will be one 360 degree revolution or less in response to the main gear rotating through an expected full main gear rotation range greater than 360 degrees. The angular position sensor further includes a processor configured to receive the first and second output signals, determine a difference between rotation of the first sensor gear and rotation of the second sensor gear based on the first and second outputs, determine an overall angular rotation of the first or second sensor gear from an initial angular position of the first or second sensor gear based on the difference and a present angular position of the first or second sensor gear, respectively, and determine an angular position of the main gear based on the overall angular rotation of the first or second sensor gear.

A torsional vibration damper

Abstract: A torsional vibration damper is provided which has an input element 54 and an output element 50 and includes spring means 52, 60 which resist the relative rotation of the input and output elements 54, 50 and which has a torsional resistance to angular displacement with a non-linear stiffness characteristic. The spring means includes first 60 and second spring 52 stages which operate in series, the first spring stage 60 operating during a first range of relative angular displacement of the input and output elements 54, 50 of the damper and which has a stiffness characteristic which increases non-linearly during the first range of angular displacement, and the second spring stage 52 operating in a second range of relative angular displacement of the input and output elements 54, 50 and which has a high stiffness. The non-linear spring stiffness characteristic may be provided by a C-shaped spring member 60, the ends of the C-shaped member being forced apart during relative angular displacement of the input and output elements 54, 50 to provide the non-linear stiffness characteristic.

High-Precision Absolute Rotary Angular Measurement by Using a Multielectrode Circular Position-Sensitive Detector

Abstract: We propose a multielectrode circular position-sensitive device that does not have any discontinuity in the detection region and has multiple electrodes for current output. We have also manufactured a prototype device. The device has a circular detection region that consists of photodiodes radially aligned with regular pitch and a resistance line connecting the outer edges of the photodiodes. All of the photocurrent excited in the photodiodes flows into the resistance line and is extracted from the electrodes connected to the resistance line at even intervals. There is no insensitive region for current output in this device since the detection region and the resistance line are separated; thus, detection with high resolution is possible at every angular position. We conducted a simulation of the detection characteristics and will propose a computational method for the position that uses four-electrode outputs in this paper. We confirmed that it is effective in minimizing the error from both the simulation and the experiment. We will also propose a measurement system of absolute angle using this method, confirming an error of less than 0.1° in the computation results.

Form measuring instrument, and calibration method and calibration program therefor

Abstract: Provided is method of calibrating Y-axis direction position of contact tip of form measuring instrument including: table rotatable about Z-axis; contact tip capable of contacting workpiece; and contact tip driving means to drive contact tip in at least X- and Z-axis directions among X-, Y- and Z-axis directions perpendicular to one another. Method performs tracing measurement of inclined surface or inclined cylinder side surface which is part of workpiece obtained by inclining workpiece placed on table about Y-axis, or side surface of off-centered cylinder having center axis off-centered in X-axis direction by rotating surface to obtain measurement value at each angular position of rotation of table, obtains angular position of rotation at which smallest value among measurement values of tracing measurement is detected as angular position of rotation with smallest detected value, and adjusts Y-axis direction position of contact tip based on angular position of rotation with smallest detected value.

Rotary flexure bearing

Abstract: This rotary flexure bearing consists of concentric inner and outer hubs connected by compound flexure stages. These compound flexure stages provide the angular compliance required for bearing rotation as well as compliance for flexure foreshortening while holding a constant axis of rotation over the entire range of motion. This design offers large angular displacement, low operating stress, low operating torque, and high stiffness in the five noncompliant degrees of freedom. The rotary flexure bearing described herein has applications in precision mechanics, particularly opto-mechanics. Specific applications include but are not limited to wafer and reticle alignment stages used in microlithography systems, mirror pointing and scanning mechanisms used in tactical and spaceborne systems, as well as flip-in mechanisms used in multiple field of view optical systems.

Method for compensating image dithering of airborne imaging equipment

Abstract: The invention provides a method for compensating imaging dithering of airborne imaging equipment The method adopts a rate gyroscope to measure the angular speed of the visual axis of a CCD camera inreal time, obtains the angular displacement of the visual axis by using an integrator for integration, measures the practical using focus of an optical zooming system by a displacement sensor, obtainsthe image displacement value of the CCD camera at the image surface due to the dithering by the calculation of a computer processing unit, and carries out reverse compensation to the image The method has simple structure and brief algorithm, reduces calculation workload, inhibits the dithering of the image and improves the quality of the video image

Carrier signal injection alternatives for sensorless control of active magnetic bearings

Abstract: This paper analyzes different forms of carrier (high frequency) excitation for sensorless control of three-pole active magnetic bearings. Three options are compared: rotating injection, pulsating injection at a fixed angular position, and pulsating injection at an angular position synchronous to the minimum reluctance axis. Criteria for comparison include sensitivity to displacement changes, parameter and operating point dependence and signal processing burden for signal isolation. Theoretical derivations, simulation results and experimental results are included. The system model and the practical implementation will be shown to share similarities with high frequency injection sensorless methods for AC machines but also to have significant differences mainly on how pulsating carrier signals are used.

Non-sensory inputs to angular path integration

Abstract: Non-sensory (cognitive) inputs can play a powerful role in monitoring one's self-motion. Previously, we showed that access to spatial memory dramatically increases response precision in an angular self-motion updating task [1]. Here, we examined whether spatial memory also enhances a particular type of self-motion updating - angular path integration. "Angular path integration" refers to the ability to maintain an estimate of self-location after a rotational displacement by integrating internally-generated (idiothetic) self-motion signals over time. It was hypothesized that remembered spatial frameworks derived from vision and spatial language should facilitate angular path integration by decreasing the uncertainty of self-location estimates. To test this we implemented a whole-body rotation paradigm with passive, non-visual body rotations (ranging 40 degrees -140 degrees ) administered about the yaw axis. Prior to the rotations, visual previews (Experiment 1) and verbal descriptions (Experiment 2) of the surrounding environment were given to participants. Perceived angular displacement was assessed by open-loop pointing to the origin (0 degrees ). We found that within-subject response precision significantly increased when participants were provided a spatial context prior to whole-body rotations. The present study goes beyond our previous findings by first establishing that memory of the environment enhances the processing of idiothetic self-motion signals. Moreover, we show that knowledge of one's immediate environment, whether gained from direct visual perception or from indirect experience (i.e., spatial language), facilitates the integration of incoming self-motion signals.