Showing papers on "Angular displacement published in 2009"

Handheld or vehicle-mounted platform stabilization system

Abstract: A hand-held or vehicle-mounted stabilization system including a platform supported by two or more rotatably-coupled gimbal frames each having a pivot assembly disposed at its rotation axis to couple an actuator to a rotation sensor having a rotation-sensitive sensor axis that is preferably fixedly disposed with respect to the rotation axis, and a controller for accepting the sensor signals and for producing each motor signal needed to dispose the platform in a predetermined angular position with respect to each rotation axis independent of changes in mount orientation. An alternative embodiment includes a controller for accepting an external slew signal sequence and for producing the motor signals needed to move the platform along a predetermined sequence of positions represented by the slew signal sequence.

Apparatus for the recognition of the presence of an object in space

Abstract: An apparatus for the recognition an object in space in accordance with the pulsed time-of-flight principle. The apparatus has a pulsed laser and a photoreceiver arrangement which receives the light pulses reflected back from the object present in the space. The apparatus has a first light deflection apparatus which outputs a first angular position signal representative of its instantaneous angular position to the evaluation circuit, wherein the first light deflection apparatus is arranged rotatably or pivotably about a first axis of rotation and is made for the transmission of light pulses following one another at changing angles in a first plane, wherein a second light deflection apparatus is arranged between the first light deflection apparatus. The apparatus outputs a second angular position signal representative of its instantaneous angular position to the evaluation circuit which has a deflection plate which is arranged rotatably or pivotably about a second axis of rotation.

Rotational Motions Observed during an Earthquake Swarm in April 1998 Offshore Ito, Japan

Abstract: We observed six components of ground rotational and translational motions in a near-field region during an earthquake swarm in April 1998 offshore Ito, Izu Peninsula, Japan. To check the reliability of our observation using a MotionPack sensor, we installed an 8301F sensor, which is an inertial angular displacement sensor with a higher sensitivity than MotionPack. The noise level of the MotionPack is much higher than that of the 8301F, but the waveforms of these signal components are quite similar to each other, suggesting that the MotionPack records rotational rate correctly but with higher noise. Our observation made known a linear correlation between the maximum rotational displacements around the vertical axis and the maximum translational velocities. The waveforms of rotational motion around the vertical axis are analogous to those of translational horizontal velocities, suggesting the linear correlation between maximum values. These rotational motions are much larger than those calculated by array data at the San Andreas fault. This large discrepancy might be explained by one or more of the following effects: the difference in the spatial scale of rotational motion by single gyro measurement and by array observation, the effect of the precipitous topography at the station of the offshore Ito swarm, and the difference of the degree of maturation between the San Andreas fault and the swarm regions of offshore Ito.

Controller for electrical machines

Abstract: The present invention relates to control of synchronous machines. A sensorless control system for an electrical machine is provided comprising a rotor and a stator having one or more phase windings for generating a rotating stator magnetic field. The current in the phase windings is monitored to determine real and imaginary components of the current vector in a rotating reference frame, from which real and imaginary components of the emf vector rotating in the rotating reference frame can also be determined. The ratio of the real and imaginary emf components is calculated, and an angular position of the rotational emf vector is estimated from this ratio. An angular error signal indicative of the deviation of the estimated angular position from a desired position in line with the real axis of the rotating reference frame is determined, and the machine is controlled such that the error signal tends towards zero.

Encoder system, signal processing method, and transmission signal generation and output device

Abstract: Disclosed is an encoder system equipped with: a first encoder that is a single rotation absolute type and that outputs a first signal according to the angular position of a first rotatable axis; a power transmission device that transfers the power of the first axis to a second rotatable axis with a prescribed transmission ratio; a second encoder that is a single rotation absolute type and that outputs a second signal according to the angular position of the second axis; and a signal-processing unit that generates data related to the quantity of rotation of the first axis based on at least the first signal and the second signal.

Dual frequency hub mounted vibration suppressor system

Abstract: A vibration suppressor system includes an annular electric motor system which independently controls rotation of at least two masses about the axis of rotation to reduce in-plane vibration of the rotating system. A method of reducing vibrations in a rotary-wing aircraft includes independently controlling a relative angular position of a multiple of independently rotatable masses to reduce vibrations of a main rotor system.

Torque sensor arrangement with rotational angle index detection

Abstract: Sensor arrangement including a torque sensor for measuring the torque acting on a first shaft, the sensor arrangement having a rotational angle index unit which is designed in such a manner that it can detect and/or identify the angular position of the first shaft with respect to a defined rotational angle and/or defined rotational angle range.

Optoelectronic joint angular sensor for robotic fingers

Abstract: The present paper reports the results of the development of a novel joint angular sensor conceived for integration in tendon-driven robotic hands and in data gloves used in virtual reality systems. The sensor is based on a couple LED/photodiode, mounted to two contiguous phalanges of a University of Bologna (UB) hand finger. When the joint between the considered phalanges flexes, the photocurrent measured by the photodetector changes with the angular displacement. An experimental model of the sensor is set up in order to select the optimal positioning of the components over the phalanges and an optical motion capture system is used to calibrate the sensor. The complete characterization of the sensor in terms of repeatability, linearity and noise presented in the paper together with its low cost confirm that the sensor can be effectively exploited both in feedback control loops for robotic systems as well as in data acquisition systems for virtual reality applications.

Experimental Analysis of Rigid Body Motion. A Vector Method to Determine Finite and Infinitesimal Displacements From Point Coordinates

Abstract: This paper presents a vector method for measuring rigid body motion from marker coordinates, including both finite and infinitesimal displacement analyses. The common approach to solving the finite displacement problem involves the determination of a rotation matrix, which leads to a nonlinear problem. On the contrary, infinitesimal displacement analysis is a linear problem that can be easily solved. In this paper we take advantage of the linearity of infinitesimal displacement analysis to formulate the equations of finite displacements as a generalization of Rodrigues' formula when more than three points are used. First, for solving the velocity problem, we propose a simple method based on a mechanical analogy that uses the equations that relate linear and angular momenta to linear and angular velocities, respectively. This approach leads to explicit linear expressions for infinitesimal displacement analysis. These linear equations can be generalized for the study of finite displacements by using an intermediate body whose points are the midpoint of each pair of homologous points at the initial and final positions. This kind of transformation turns the field of finite displacements into a skew-symmetric field that satisfies the same equations obtained for the velocity analysis. Then, simple closed-form expressions for the angular displacement, translation, and position of finite screw axis are presented. Finally, we analyze the relationship between finite and infinitesimal displacements, and propose vector closed-form expressions based on derivatives or integrals, respectively. These equations allow us to make one of both analyses and to obtain the other by means of integration or differentiation. An experiment is presented in order to demonstrate the usefulness of this method. The results show that the use of a set of markers with redundant information (n>3) allows a good accuracy of measurement of kinematic variables.

Modeling of a Cartwheel Flexural Pivot

Abstract: A cartwheel flexural pivot has a small center shift as a function of loading and ease of manufacturing. This paper addresses an accurate model that includes the loading cases of a bending moment combined with both a horizontal force and a vertical force. First, a triangle flexural pivot is modeled as a single beam. Then, the model of cartwheel flexural pivot based on an equivalent model is developed by utilizing the results of the triangle pivot. The expressions for rotational displacement and center shift are derived to evaluate the primary motion and the parasitic motion; the maximum rotational angle is simply formulated to predicate the range of motion. Finally, the model is verified by finite element analysis. The relative error of the primary motion is less than 1.1% for various loading cases even if the rotational angle reaches ±20 deg, and the predicted errors for the two center shift components are less than 15.4% and 7.1%. The result shows that the model is accurate enough for designers to use for initial parametric design studies, such as for conceptual design.

Inaccuracies of Giant Magneto-Resistive Angle Sensors Due to Assembly Tolerances

Abstract: For automotive applications like steering wheel position, sensing the angular position of a mechanical axel is detected in a contactless way: a small permanent magnet at the end of the shaft is magnetized perpendicularly to the axis of rotation, and a magnetic field sensor is placed ahead. Even though the magnetic field sensor may be calibrated to have virtually no errors, assembly tolerances of the magnet and the sensor lead to errors in the estimated angular position of the shaft. A Taylor series expansion of the magnetic field up to second order is used to approximate these angle errors. Results of Monte-Carlo simulations show that worst case angle errors may be up to 10 times the average angle error due to error propagation in the nonlinear goniometric relationships. Various shapes of magnets are discussed and criteria for optimization are given. The strong effects of magnet size and distance between sensor and magnet are explained and the limit of infinite homogeneous magnetic field is derived. The results can be used to anticipate production spread of angle sensor systems.

Determining initial rotor position of an alternating current motor

Abstract: Determination of an estimated initial angular position of the rotor of an AC motor includes application of voltages corresponding to a high frequency reference signal vector to the stator windings of the motor and production of an estimated initial angular position of the rotor as a function of the resulting q-axis stator current component iq_HF, adjustment of transformation of signal vectors from stationary to rotating coordinates and vice versa using the estimated angular position and production of an adjusted estimated angular position of the rotor as a function of the q-axis stator current component as adjusted. Determination of an initial estimated angular position of the rotor and production of an adjusted initial estimated angular position of the rotor is performed with the rotor at standstill and before initially applying voltage corresponding to the drive signal vector to the stator windings, and production of an initial value of a drive signal vector command in stationary coordinates uses the adjusted estimated angular position. Determination of an estimated angular position of the rotor after application of stator current may use a different method, such as a physical relative position sensor.

Process cartridge, electrophotographic image forming apparatus and electrographic photosensitive drum unit

Abstract: A process cartridge which is detachably mountable to a main assembly of an electrophotographic image forming apparatus includ-ing a driving shaft (180) having a rotational force applying portion by moving in a direction substantially perpendicular to an axis of the driving shaft, includes i) an electrophotographic photosensitive drum rotatable about an axis; ii) a coupling member engageable with the rotational force applying portion to receive a rotational force for rotating the drum, the coupling member being capable of taking a rotational force transmitting angular position for transmitting the rotational force, a pre-engagement angular position in which the coupling member is inclined away from the axis and a disengaging angular position in which the coupling member is inclined away from the axis and iii) a regulating portion (170) for regulat-ing an inclination angle of the coupling member such that downward in-clination angle of the coupling member is smaller than an inclination an-gle of the coupling member when the coupling member is at the pre-en-gagement angular position, wherein in mounting the cartridge to the main assembly, the coupling member moves from the pre-engagement angular position to the rotational force transmitting angular position, and in dis-mounting the cartridge from the main assembly, the coupling member moves from the rotational force transmitting angular position to the disen-gaging angular position to disengage from the driving shaft.

Estimating rotor angular position and velocity and verifying accuracy of position sensor outputs

Abstract: Methods, system and apparatus are provided for estimating rotor angular position and angular velocity during a position sensor fault, and for verifying the accuracy or inaccuracy of a position sensor's outputs based on the estimated rotor angular position and angular velocity of the rotor following a position sensor fault.

Scanning Mirror Control

Abstract: A scanning beam projection system (100) includes a scanning mirror (116) having a fast-scan axis and a slow-scan axis. Movement on the slow-scan axis is controlled by a slow-scan scanning mirror control system (130). The control system receives position information describing angular displacement of the mirror. An outer loop of the control system operates in the frequency domain and determines harmonic drive coefficients for a scanning mirror drive signal. An inner loop of the control system operates in the time domain and compensates for a scanning mirror resonant vibration mode at a frequency within the frequency band occupied by the harmonic drive coefficients.

Scanning mirror control having least mean square tone adder

Abstract: A scanning beam projection system (100) includes a scanning mirror (116) having a fast-scan axis and a slow-scan axis. Movement on the slow-scan axis is controlled by a slow-scan scanning mirror control system (130). The control system receives position information describing angular displacement of the mirror. An outer loop of the control system includes least mean square (LMS) tone adders that determine harmonically related signals that when combined produce a scanning mirror drive signal. An inner loop of the control system compensates for a scanning mirror resonant vibration mode at a frequency within the frequency band occupied by the harmonically related signals.

Inductive Displacement Sensor for Force Measuring in Humanoid Robotic Application: Testing the Invariance on Angular Displacement

Abstract: — A planar displacement inductive sensor, usable in robotics, is presented in the paper. The sensor is composed of two sensor elements. The first sensor element detects vertical displacement while the second sensor element detects horizontal displacement. Combining information from these two sensor elements, it is possible to determine displacement in a plane. Sensor element is a pair of meander coils. One coil is a fixed coil and has the input while the other coil is short-circuited and moves in x-z plane. The variation of input inductance between coils serves as a measure of displacement. The goal of this paper is to show that the variation of the input inductance is invariant to angular displacement of a moving coil, which is important for implementation of the sensor in humanoid robot’s foot. Calculated results were obtained using a new simulation tool developed in MATLAB.

Design and Basic Characteristics of Multi-Consequent-Pole Bearingless Motor With Bi-Tooth Main Poles

Abstract: A multi-consequent-pole bearingless motor which is adapted to low speed rotation is presented. The bearingless motor can be used in swinging stages (or platforms) under specific conditions. Two degrees of freedom (2DOF) are actively controlled in the radial x-y directions. A gap sensor is required to control each DOF. Although 2DOF bearingless motors almost have a flat rotor so that axial length of the rotor is small, the device needs gap sensors and its target. In this paper, a novel stator structure is proposed and a design procedure considers the installation of the gap sensors on the stator. Three dimensional finite element analyses are carried out. An amplitude pulsation and a direction error of the radial suspension force with respect to the rotor rotational angular position are evaluated. Two machines with a conventional stator and the proposed stator are tested and compared. It is shown the proposed machine has beneficial performance by experimental verification.

Angular displacement and deformation analyses using a speckle-based wavefront sensor

Abstract: Wavefronts incident on a random phase plate are reconstructed via phase retrieval utilizing axially displaced speckle intensity measurements and the wave propagation equation. Retrieved phases and phase subtraction facilitate the investigations of wavefronts from test objects before and after undergoing a small rotation or deformation without sign ambiguity. Angular displacement (Deltatheta) between incident planar wavefronts is determined from the light source vacuum wavelength (lambda) divided by the fringe spacing (Lambda). Fourier analysis of the wavefront phase difference yields a peak frequency that is inversely proportional to Lambda, and the sign gives the direction of rotation. Numerical simulations confirm the experimental results. In the experiments, the smallest Deltatheta measured is 0.031 degrees . The technique also permits deformation analysis of a reflecting test object under thermal loading. The technique offers simple, high resolution, noncontact, and whole field evaluation of three-dimensional objects before and after undergoing rotation or deformation.

Angle measurement system

Abstract: Some aspects of the present disclosure relate to techniques for measuring an angular position of a rotating shaft. As will be described in greater detail below, some angle measurement systems of the present disclosure include at least two magnets that cooperatively rotate at different rates according to a predetermined relationship (e.g., a predetermined gear ratio). Two or more magnetic field sensing elements, which are often stationary, measure the directionality of the resultant magnetic field at different positions for a particular angular shaft position. Based on the directionality measured by the magnetic field sensing elements, the techniques can determine an absolute angular position of the rotating shaft, which can be greater than three-hundred and sixty degrees.

Suboptimal controller design for flexible launch vehicle based on genetic algorithm: Selection of the weighting matrices Q and R

Abstract: In this study, a suboptimal controller for the pitch plane motion of a flexible launch vehicle is presented. Three sensors for measuring the motion, angular position sensor, angular rate sensor and accelerometer, are considered and assumed to be at given positions on a rocket described by a ninth-order state-space dynamical model, including three bending modes. The weighting matrices with respect to the suboptimal control method, which are used to synthesize a performance index, are selected by the genetic algorithm. Additionally, in order to improve the robust performance of the flexible launch vehicle, various uncertainty combinations are predetermined and considered in the process of the genetic search. The simulation results indicate that both the rigid body and flexible mode response are desirable, and the control performance including the robust performance is better than that of the suboptimal controller with manual selection of the weighting matrices.

A Pressure Angle Function Method for Describing Tooth Profiles of Planar Gears

Abstract: A general mathematical model for describing the geometries and the geometric characteristics of meshing tooth profiles of planar gears is established. The function of pressure angle in the angular displacement of gears, called the pressure angle function (PAF), is introduced to characterize this model. The different tooth profiles and their geometric properties could be generated and analyzed logically and systematically by using this model and defining various PAFs. This new method is applicable to any type of gear pairs including circular or noncircular. In addition, by using this method, it is relatively easy to realize the desired geometrical and mechanical properties into the design.

Systems and methods for determining the angular position of a wind turbine rotor

Abstract: Certain embodiments of the invention may include systems and methods for determining an angular position of a wind turbine rotor. According to an exemplary embodiment of the invention, the method for determining an angular position of a wind turbine may include measuring tangential acceleration and radial acceleration of the rotor, measuring speed of the rotor, determining rotational tangential acceleration of the rotor based at least in part on the change of rotor speed over time, determining rotational radial acceleration based at least in part on the rotor speed, adjusting the measured tangential acceleration based at least in part on the determined rotational tangential acceleration, adjusting the measured radial acceleration based at least in part on the determined rotational radial acceleration, and determining an angular position of the rotor based at least on the adjusted tangential acceleration and the adjusted radial acceleration.

Mathematical analysis of rotor shaft displacements in asynchronous machines; a critical speed or just a rotation of the orbit axis?

Abstract: This paper presents a mathematical analysis of rotor shaft displacements in asynchronous machines caused by different types of rotor eccentricity. Based on a simplified rotor model, the theoretical coherence between electromagnetic, rotor dynamic, and the specific characteristics of sleeve bearings is shown. The orbits of the rotor mass and the shaft journal are mathematically described for each kind of eccentricity and the shaft displacement with respect to two virtual fixed sensors is derived. Based on this theoretical description and on a numerical example, the paper shows that focusing in a theoretical rotor dynamic analysis only on the calculated amplitudes in direction of two fixed sensor positions, may lead to wrong conclusions concerning the evaluation of resonances. The aim of this paper is, based on a simplified rotor model, to show the mathematical coherence concerning typical rotor eccentricities in asynchronous machines and to demonstrate the necessity to focus not only on the amplitudes relative to two fixed sensor positions, but to also consider the semi-major axis of the calculated orbit and its angular position. The aim of the paper is not to replace a detailed finite element rotor dynamic analysis by a simplified analytical rotor model for predicting the real shaft vibrations. The intension is to prepare the basis for adopting the conclusions, derived from a simplified analytical model, into a more detailed rotor dynamic model – e.g. a finite element rotor dynamic model – and therefore to derive a more precise theoretical analysis of the real shaft displacements.

Electromechanical transducer device

Abstract: An electromechanical transducer device for a vehicle transmission or drive has a lever ( 1 ) that can be pivotally actuated about at least one first axis ( 2 a , 2 b ) and which is mechanically decoupled from the transmission or drive. The lever is supported by a suspension ( 3 ) on the first axis ( 2 a , 2 b ). The axis ( 2 a , 2 b ) comprises at least one first component ( 6 a , 6 b ) of a magnetic rotational angle sensor system ( 6 a , 6 b , 7 a , 7 b ) at an axial end section to detect angular position or rotational movement of the lever ( 1 ). A second component ( 7 a , 7 b ) of the rotational angle sensor system is arranged on the suspension ( 3 ) opposite of the end section of the axis ( 2 a , 2 b ), wherein the axial end section is located within the suspension ( 3 ). A circuit board ( 15 ) accommodating the rotational angle sensors ( 7 a , 7 b ) is arranged on the suspension ( 3 ), and the circuit board ( 15 ) comprises at least one flange-like extension ( 17, 18 ) protruding from the circuit board plane.

Belt drive control device, belt device, image forming apparatus, and belt drive control method

Abstract: A belt drive control device includes: first and second detection devices which detect the angular displacement or velocity of a driven rotary member and the angular displacement or velocity of a drive rotary member, respectively; an extraction device which extracts, from the difference between the detection results of the first and second detection devices, the amplitude and phase of a variation component due to belt thickness variation; a control device which controls the rotation of the drive rotary member in accordance with the extracted amplitude and phase; first and second holding devices which hold the extracted amplitude and phase and normal ranges of the amplitude and phase, respectively; and first and second feedback devices which feed back the amplitude and phase to the rotation control, and performs feedback by using a substitution value for the amplitude or phase if the amplitude or phase is out of the normal range, respectively.

Rate gyro stabilizing platform type antenna followup system

Abstract: The invention provides a follow-up tracking system of a rate gyroscope stabilized platform type antenna, which comprises a direction-finding device, an adjustment link, a PID controller, a PWM driver, a moment motor, an angle measuring potentiometer, an angular rate gyroscope and a differential link The PWM driver, the moment motor, the angular rate gyroscope and the differential link are connected in sequence to form an angular acceleration negative feedback loop; the PID controller, the PWM driver, the moment motor and the the angular rate gyroscope are connected in sequence to form an angular rate negative feedback loop; the direction-finding device, a preamplifier, the adjustment link and the angular rate negative feedback circuit form an angular position negative feedback loop; the angle measuring potentiometer, the preamplifier, the adjustment link and the angular rate negative feedback loop form an angle searching loop The follow-up tracking system is an antenna follow-up system which is used for realizing the follow-up tracking technology of stably tracking, searching and isolating the angular motion of a carrier in the direction-finding devices, such as radars, optical imaging, and the like, in moving carriers so as to realize high precision, weak coupling, anti-turn-off performance, fastness and stabilization and realize proportional guidance

Angular displacement perception modulated by force background.

Abstract: We had recumbent subjects (n = 7) indicate the amplitude of imposed, passive yaw–axis body rotations in the 0, 1, and 1.8 g background force levels generated during parabolic flight maneuvers. The blindfolded subject, restrained in a cradle, aligned a gravity-neutral pointer with the subjective vertical while in an initial position and then tried to keep it aligned with the same external direction during a body rotation, lasting less than 1.5 s about the z-axis 30°, 60°, or 120° in amplitude. All the rotations were above semicircular threshold levels for eliciting perception of angular displacement under terrestrial test conditions. In 1 and 1.8 g test conditions, subjects were able to indicate both the subjective vertical and the amplitude of the body rotation reasonably accurately. By contrast in 0 g, when indicating the subjective vertical, they aligned the pointer with the body midline and kept it nearly aligned with their midline during the subsequent body tilts. They also reported feeling supine throughout the 0 g test periods. The attenuation of apparent self-displacement in 0 g is discussed in terms of (1) a possible failure of integration of semicircular canal velocity signals, (2) a contribution of somatosensory pressure and contact cues, and (3) gravicentric versus body-centric reference frames. The significance of the findings for predicting and preventing motion sickness and disorientation in orbital space flight and in rotating artificial gravity environments is discussed.