Showing papers on "Angular displacement published in 2011"

Power screwdriver having rotary input control

Abstract: A power tool includes an output shaft configured to rotate about a longitudinal axis, a motor drivably connected to the output shaft to impart rotary motions thereto, and a rotational motion sensor spatially separated from the output shaft and operable to determine the user-imparted rotational motion of the power tool with respect to the longitudinal axis. A controller is electrically connected to the rotational motion sensor and the motor. The controller determines angular velocity of the power tool about the axis, rotational displacement of the power tool about the axis, and/or a direction of the rotational displacement using input from the rotational motion sensor. The controller then controls the motor according to the angular velocity, the rotational displacement, and/or the direction of the rotational displacement.

Construction of an error map of rotary axes on a five-axis machining center by static R-test

Abstract: This paper proposes an efficient and automated scheme to calibrate error motions of rotary axes on a five-axis machining center by using the R-test. During a five-axis measurement cycle, the R-test probing system measures the three-dimensional displacement of a sphere attached to the spindle in relative to the machine table. Location errors, defined in ISO 230-7, of rotary axes are the most fundamental error factors in the five-axis kinematics. A larger class of error motions can be modeled as geometric errors that vary depending on the angular position of a rotary axis. The objective of this paper is to present an algorithm to identify not only location errors, but also such position-dependent geometric errors, or “error map,” of rotary axes. Its experimental demonstration is presented.

iHandRehab: An interactive hand exoskeleton for active and passive rehabilitation

Abstract: This paper presents an interactive exoskeleton device for hand rehabilitation, iHandRehab, which aims to satisfy the essential requirements for both active and passive rehabilitation motions. iHandRehab is comprised of exoskeletons for the thumb and index finger. These exoskeletons are driven by distant actuation modules through a cable/sheath transmission mechanism. The exoskeleton for each finger has 4 degrees of freedom (DOF), providing independent control for all finger joints. The joint motion is accomplished by a parallelogram mechanism so that the joints of the device and their corresponding finger joints have the same angular displacement when they rotate. Thanks to this design, the joint angles can be measured by sensors real time and high level motion control is therefore made very simple without the need of complicated kinematics. The paper also discusses important issues when the device is used by different patients, including its adjustable joint range of motion (ROM) and adjustable range of phalanx length (ROPL). Experimentally collected data show that the achieved ROM is close to that of a healthy hand and the ROPL covers the size of a typical hand, satisfying the size need of regular hand rehabilitation. In order to evaluate the performance when it works as a haptic device in active mode, the equivalent moment of inertia (MOI) of the device is calculated. The results prove that the device has low inertia which is critical in order to obtain good backdrivability. Experimental analysis shows that the influence of friction accounts for a large portion of the driving torque and warrants future investigation.

Optoelectronic sensor and method for recording and determining the distance of an object

Abstract: The laser scanner (10) has a rotary deflecting unit (18) for periodically deflecting the transmission light beam (16) in the monitoring area. Based on the angle position of the defecting unit, an angle encoding unit (30) generates an angular position signal. An evaluation unit (32) selects a respective group of reception pulses that is collected in a histogram based on the angular position signal and assigns the measured value for the object distance determined from the histogram of the group of reception pulses to a detection angle identified by the angular position signal. An independent claim is also included for a method for the detection and distance determination of objects in a monitoring area.

Measurement of six degrees of freedom head kinematics in impact conditions employing six accelerometers and three angular rate sensors (6aω configuration).

Abstract: The ability to measure six degrees of freedom (6 DOF) head kinematics in motor vehicle crash conditions is important for assessing head-neck loads as well as brain injuries. A method for obtaining accurate 6 DOF head kinematics in short duration impact conditions is proposed and validated in this study. The proposed methodology utilizes six accelerometers and three angular rate sensors (6aω configuration) such that an algebraic equation is used to determine angular acceleration with respect to the body-fixed coordinate system, and angular velocity is measured directly rather than numerically integrating the angular acceleration. Head impact tests to validate the method were conducted using the internal nine accelerometer head of the Hybrid III dummy and the proposed 6aω scheme in both low (2.3 m/s) and high (4.0 m/s) speed impact conditions. The 6aω method was compared with a nine accelerometer array sensor package (NAP) as well as a configuration of three accelerometers and three angular rate sensors (3aω), both of which have been commonly used to measure 6 DOF kinematics of the head for assessment of brain and neck injuries. The ability of each of the three methods (6aω, 3aω, and NAP) to accurately measure 6 DOF head kinematics was quantified by calculating the normalized root mean squared deviation (NRMSD), which provides an average percent error over time. Results from the head impact tests indicate that the proposed 6aω scheme is capable of producing angular accelerations and linear accelerations transformed to a remote location that are comparable to that determined from the NAP scheme in both low and high speed impact conditions. The 3aω scheme was found to be unable to provide accurate angular accelerations or linear accelerations transformed to a remote location in the high speed head impact condition due to the required numerical differentiation. Both the 6aω and 3aω schemes were capable of measuring accurate angular displacement while the NAP instrumentation was unable to produce accurate angular displacement due to double numerical integration. The proposed 6aω scheme appears to be capable of measuring accurate 6 DOF kinematics of the head in any severity of impact conditions. Language: en

Dynamics analysis and characteristics of the 8-PSS flexible redundant parallel manipulator

Abstract: The modeling methodology and the dynamic characteristics of the 8-PSS flexible redundant parallel manipulator are investigated based on some basic assumptions. Firstly, the system description and the rigid dynamic model are presented. The actuating forces with minimum norm and least quadratic sum among the possible actuating forces are achieved. Then, the kineto-elastodynamic model of the manipulator is developed by virtue of the finite element method and the substructure synthesis technique. Finally, the dynamic characteristics represented by the natural frequency, the sensitivity analysis, the energy ratios and the displacement responses of the moving platform are investigated through simulation. It is shown that the second order natural frequency is a little higher than the first order natural frequency for the 8-PSS flexible redundant parallel manipulator. The first order natural frequency is much more sensitive to the radius of the lead-screws than to the radius of the struts. From the computation of the energy ratio distribution, the mass of the moving platform should be reduced or the stiffness of the strut should be increased in order to improve the dynamic characteristic of the manipulator. For the investigated trajectory, the displacement response of the moving platform along the x direction is slightly larger than these displacement responses along the y direction and along the z direction. The angular displacement response of the moving platform rotating about the x axis is slightly larger than those angular displacement responses rotating about the y axis and about the z axis.

Nonlinear deformation behavior of a beam-based flexural pivot with monolithic arrangement

Abstract: Manufacturing the cross-spring pivot is not an easy task because of the non-monolithic arrangement. This problem can be resolved by moving the intersection point of the pivot to a remote position. However, the in-plane configuration leads to nonlinear behavior for the monolithic flexural pivot. In this paper, the nonlinear models of stiffness and center shift are developed for parametric insight of the large deformation behavior. The influences of both two drive loads (the horizontal force and bending moment) on the rotational stiffness are characterized, and the load stiffening effect induced by the payload is analyzed. Meanwhile, the nonlinear relationships between center shift and angular displacement are investigated to provide reference for combination of the building blocks. In addition, the effect of loads on the center shift is also evaluated, which is an important consideration in the design of compliant mechanisms. Finally, the nonlinear characteristics, revealed by the analysis model, are validated by finite element analysis (FEA).

System and method for a marine vessel autopilot

Abstract: An autopilot system includes a navigation application for computing angular position and angular turn rate of a pilot line and an autopilot steering application for calculating steering commands for a ship steering device. The pilot line provides directional guidance to a ship and is a vector having one end attached to a point on the ship and a second end pointing to a desired direction. The autopilot steering application receives the computed pilot line angular position and angular turn rate and calculates angular position steering commands for the steering device. The steering commands are calculated by taking into account the difference between the pilot line angular position and the ship's angular position and the difference between the pilot line angular turn rate and the ship's angular turn rate.

Analysis of the Vehicle Brake Judder Problem by Employing a Simplified Source—Path—Receiver Model:

Abstract: An analytical formulation of the brake judder problem caused by disc thickness variation is described by using a simplified source—path—receiver model. Eigenvalue analysis is first conducted to determine the transfer mechanism from the brake source to the steering-wheel receiver. Calculations show that the peak vibration levels of the steering wheel are seen when the rotational frequency of the tyre coincides with the resonant frequency of the transfer path; in this case, only the first-order disc thickness variation is considered. The effects of two key parameters, associated with the source and the path respectively, are analytically and computationally studied. Analysis suggests that the lower pad stiffness and/or the higher bushing stiffness should effectively reduce the vibration levels. Finally, a new vibration control concept is proposed that modulates the actuation pressure; it is based on an approximate solution for the angular displacement of the disc in the model developed here. Preliminary wor...

Method and system for estimating a path of a mobile element or body

Abstract: A method for estimating a path of a moving element or body using a sensor assembly includes: receiving acceleration values provided by an accelerometer; receiving angular velocity values provided by a gyrometer; processing the values provided for estimating at least one angular position value using the angular velocity values and at least two Cartesian position values defining a path of the moving element or body using acceleration values and the at least one previously estimated angular position value; estimating rotation parameters, by inverting a rotational realignment model of the estimated path subject to prior knowledge of the path; retroactively correcting the at least one estimated angular position value, by applying a rotation on this value using estimated rotation parameters, so as to provide at least one corrected angular position value.

Tool and method for measuring deflection angle of airplane control surface

Abstract: The invention discloses a tool and a method for measuring the deflection angle of an airplane control surface. The measuring tool comprises a control surface clip (1), a stabilizer clip (6), a brace rod (5), a regulating arm (4), a sensor support (3), an angular displacement sensor (7) and a forked rocker arm (2). The measuring process comprises the following steps: clamping the stabilizer clip (6) of the measuring tool to a force-bearing position of a vertical tail stabilizer (45), sequentially mounting the brace rod (5), the regulating arm (4), the sensor support (3), the angular displacement sensor (7) and the forked rocker arm (2) in place, clamping the control surface clip (1) to a force-bearing position of an upper rudder (46), and moving the angular displacement sensor (7) to a rotary shaft of the upper rudder (46) so as to measure the deflection angle of the control surface. The invention can be simultaneously used for measuring the deflection angle of the rudder or the elevator in the bench test or the ground built-in test of an airplane, can be directly used for measuring the deflection angle of the control surface without disassembling structural parts of the airframe, and is especially suitable for the condition that the deflection amount can not be educed for measurement by means of a link mechanism in case that the rotary shaft is arranged inside the envelope of the control surface.

A Three Degree-of-Freedom Optical Orientation Measurement Method for Spherical Actuator Applications

Abstract: The advance of robotics, actuators and manufacturing technology motivates the research on measurement of multiple degree-of-freedom (DOF) rotational motions. A novel laser-based noncontact high-precision spherical displacement measurement methodology has been proposed for spherical actuator applications in this paper. The laser detector is utilized to measure the distance from the target to the detector on several light spots, and thus to calculate the rotation angle of the rigid body in three directions. As there is no physical contact between the laser detector and the moving body, additional mass/moment of inertia and friction on the rotor are avoided, and thus the working efficiency of moving body can be improved. The algorithm of orientation angles has been derived. Experimental apparatuses have been developed to evaluate the working performance of the measurement method. Comparison between experimental and analytical results shows that the proposed method can achieve high-precision measurement for multi-DOF rotational motions. Precision of the laser-based angular displacement measurement method can be improved further by increasing the slot density on the rigid body or using new models of laser detectors.

Applications of linear Hall-effect sensors on angular measurement

Abstract: The non-contact type application on the permanent magnet and linear Hall-effect sensor gauging rotary system is introduced in this paper. For such a contactless case, there is no wear. This provides a longer life span in association, and in particular, high reliability to achieve continuous use. The main component of the angular position estimation system is the linear Hall-effect sensor. The angle gauge depends on the Hall voltage at the rotation of the magnetic induction. The advantage of the system is its reliable operation in special environmental conditions, such as high vibration, humidity, or dust. Higher accuracy and precision will be achieved, as shown by the experimental results, and it can be widely used in the angular measurement field.

Bending fluidic actuator for smart structures

Abstract: This paper presents a novel silicone-based, millimeter-scale, bending fluidic actuator (BFA). Its unique parallel micro-channel design enables, for the first time, operation at low working pressure while at the same time having a very limited thickness expansion during pressurization. It also enables the actuator to have the highest ratios of angular displacement over length and torque over volume among previously proposed BFAs. In this work, this parallel micro-channel design is implemented by embedding the BFA with an innovative single winding conduit, which yields a simple, single-component configuration suitable for low-cost production and reliable performance. The BFA design can be easily scaled down to smaller dimensions and can be adapted to applications in restricted space, particularly minimally invasive surgery. In this work, the actuator is manufactured in TC-silicone through poly(methyl methacrylate) molds obtained by using laser cutting technology. Repeated angular displacement measurements on multiple prototypes having different stiffness are carried out. The experimental results are compared with an analytical model, which accurately predicts the performance of the device.

Methods, systems and apparatus for controlling a multi-phase inverter

Abstract: Embodiments of the present invention relate to methods, systems, a machine-readable medium operable in a controller, and apparatus for controlling a multi-phase inverter that drives a multi-phase electric machine. When a sensor fault is detected, a phase current angle is computed based on the feedback stator currents, and used to estimate an angular velocity and an angular position of a rotor of the multi-phase electric machine. When the estimated angular velocity of the multi-phase electric machine is less than a transition angular velocity threshold, an open-circuit response can be applied at the multi-phase inverter by controlling all switches in the multi-phase inverter drive to be open. By contrast, when the estimated angular velocity is greater than the transition angular velocity threshold, a short-circuit response can be applied at the multi-phase inverter by controlling selected switches in the multi-phase inverter drive to connect all phases of the multi-phase inverter to a single bus (e.g., either the plus bus or the minus bus).

Wireless transmission torque wrench with angular orientation correction

Abstract: Disclosed is a torque wrench with wireless transmission function, including at least one wrench body having an end to which a tool head is coupled for coupling with a tool piece, such as wrench socket, for application of torque, at least one toque-strain bar, which is coupled to the tool head of the wrench body, at least one torque sensor, which is mounted to the toque-strain bar to detect the value of the torque transmitted to the toque-strain bar, at least one angular position sensor, which is set inside the wrench body to detect a horizontal angle of the body and the tool head, at least one detection and processing circuit, which is arranged in the wrench body and connected to the torque sensor and the angular position sensor to convert detected torque and angle into digital torque and angle data for displaying or issuing an alarm and to transmit the torque and angle data in a bi-directional wireless manner, and at least one control receiver, which receives the torque and angle data from the detection and processing circuit for subsequent applications.

Apparatuses and methods for magnetometer alignment calibration without prior knowledge of the local magnetic

Abstract: Apparatuses and methods calibrate attitude dependent magnetometer alignment parameters of a magnetometer mounted together with other angular position sensors on a device without prior knowledge of the local magnetic field and allowing a constant but unknown offset of the yaw angle in the reference attitudes with respect to an earth-fixed coordinate system. The method includes acquiring magnetic field measurements from the magnetometer and corresponding estimated angular positions subject to an unknown yaw offset relative to a gravitational reference system. The method further includes iteratively computing a scale and vector components of a quaternion representing a misalignment matrix, an inclination angle of local magnetic field, and a yaw angle offset, using an extended Kalman filter (EKF) infrastructure with a specific designed model and constraints, based on the magnetic field measurements and the corresponding estimated angular positions.

Experimental System for One-Dimensional Rotational Brownian Motion

Abstract: We present here an experimental, strictly one-dimensional rotational system, made by using single magnetic Janus particles in a static magnetic field. These particles were half-coated with a thin metallic film, and by turning on a properly oriented external static magnetic field, we monitor the rotational Brownian motion of single particles, in solution, around the desired axis. Bright-field microscopy imaging provides information on the particle orientation as a function of time. Rotational diffusion coefficients are derived for one-dimensional rotational diffusion, both for a single rotating particle and for a cluster of four such particles. Over the studied time domain, up to 10 s, the variation of the angle of rotation is strictly Brownian; its probability distribution function is Gaussian, and the mean squared angular displacement is linear in time, as expected for free diffusion. Values for the rotational diffusion coefficients were also determined. Monte Carlo and hydrodynamic simulations agree wel...

Image processing device, image processing method, program, and imaging device

Abstract: The picture processing device of the present invention includes: a rotational motion distance calculating unit (22) which calculates a rotational motion distance of a second picture with respect to a first picture; a cutout picture generating unit (243) which (i) generates a first cutout picture from the first picture, and (ii) and generates a second cutout picture from a first corrected picture, the first corrected picture being generated from the second picture whose rotational displacement amount, in a combination of directions in three axes, is corrected; a parallel motion amount calculating unit (24) which calculates a parallel motion amount of a second cutout picture with respect to the first cutout picture; and a motion amount determining unit (26) which determines a motion amount of the second picture with respect to the first picture.

Rotary encoder that detects rotation angle

Abstract: A rotary encoder 100 includes a scale 201 that includes a spiral pattern 501 and a radial pattern 502 to be rotatable around a rotation axis, a first sensor unit 301 that detects a light transmitted through the spiral pattern 501 to output a first detection signal, a second sensor unit 302 that detects a light transmitted through the radial pattern 502 to output a second detection signal, and a signal processing circuit 401 that generates an eccentricity correction signal based on the first detection signal to correct the second detection signal based on the eccentricity correction signal. The spiral pattern 501 detects a rotational angular displacement larger than a predetermined value, and the radial pattern 502 detects a rotational angular displacement smaller than the rotational angular displacement detected by the spiral pattern 501.

Double-parallelogram non-angular displacement vibration damper

Abstract: The utility model relates to a vibration damper, in particular to a double-parallelogram non-angular displacement vibration damper which is mainly used in aviation field and used for arranging aerial cameras, comprises a base platform, a load platform, link mechanisms and a vibration damper, and is characterized in that four double-parallelogram link mechanisms are arranged on four edges of the base platform and the load platform, and angular displacement is converted into linear displacement by utilizing the four double-parallelogram link mechanisms arranged on four edges of the base platform and the load platform. Therefore, the aerial camera installed on the load platform does not generate angular displacement, non-angular displacement damping effect is realized, and the shooting quality is greatly improved; furthermore, the requirement on imaging with high resolution can be met, therefore, the double-parallelogram non-angular displacement vibration damper is an aerial camera vibration damper which has high cost performance and is economical and practical.

Elastic displacement of a technological system in face milling with tool wear

Abstract: For an end mill, a two-factor mathematical model is developed for the elastic displacement of the tooth tip in the direction of the machined dimensions. In the model, the mutual angular displacement of the system components is taken into account.

Robotic ball device with improved robustness and a multitude of interactive and sensing capabilities

Abstract: A robotic ball device having a center point and an axis of rotation passing through the center point around which the robotic ball device rotates during motion in a forward linear direction includes a housing and a defined pathway located on an inner face of the housing that forms a closed loop around the axis of rotation. A rolling member is contained in the housing and movably disposed on the defined pathway. An actuator is coupled to the rolling member for actuating rotation of the rolling member. A weighted component is operationally coupled to the rolling member, and the weighted component is sufficiently heavy to maintain the rolling member, during a motion in the forward linear direction, at a substantially constant angular position in a forward vertical plane, which dissects the rolling member, relative to an origin in a moving frame of reference that moves with the robotic ball device.

Analysis and design considerations of a 2-DoF rotary-linear actuator

Abstract: In this paper, a permanent magnet actuator with two degrees of freedom is analyzed. The actuator can provide rotation and translation independently controlled. Additionally, passive gravity overcompensation is included in the actuator, i.e., during power down conditions, the translator will be at rest in its upper position. The different aspects of this actuator are described and a prototype is designed for a pick and place application. The actuator is designed for a maximum acceleration level in the axial direction of 150 ms−2 for a stroke of 45 mm and a peak force of 40 N. For rotation, the requirements are a torque level of 20 mNm and an angular position accuracy of 0.12 mrad.