Angular Velocity Measurements Research Articles

A Calculation Method of Bearing Balls Rotational Vectors Based on Binocular Vision Three-Dimensional Coordinates Measurement

The rotational speed vectors of the bearing balls affect their service life and running performance. Observing the actual rotational speed of the ball is a prerequisite for revealing its true motion law and conducting sliding behavior simulation analysis. To address the need for accuracy and real-time measurement of spin angular velocity, which is also under high-frequency and high-speed ball motion conditions, a new measurement method of ball rotation vectors based on a binocular vision system is proposed. Firstly, marker points are laid on the balls, and their three-dimensional (3D) coordinates in the camera coordinate system are calculated in real time using the triangulation principle. Secondly, based on the 3D coordinates before and after the movement of the marker point and the trajectory of the ball, the mathematical model of the spin motion of the ball was established. Finally, based on the ball spin motion model, the three-dimensional vision measurement technology was first applied to the measurement of the bearing ball rotation vector through formula derivation, achieving the analysis of bearing ball rolling and sliding characteristics. Experimental results demonstrate that the visual measurement system with the frame rate of 100 FPS (frames per second) yields a measurement error within ±0.2% over a speed range from 5 to 50 RPM (revolutions per minute), and the maximum measurement errors of spin angular velocity and linear velocity are 0.25°/s and 0.028 mm/s, respectively. The experimental results show that this method has good accuracy and stability in measuring the rotation vector of the ball, providing a reference for bearing balls' rotational speed monitoring and the analysis of the sliding behavior of bearing balls.

Bicycling tasks relation to stability measures during alcohol intoxication

Bicycling accidents are a major traffic safety problem and are deemed ‘an unacceptable human and social price for EU citizens’. One of the major causes for bicycling accidents is loss of balance. A related influencing factor is alcohol intoxication. It is a primary, long term, safety objective to develop safety systems for the cyclist. The present work aimed to understand how to measure cyclists’ instability via steering and leaning inputs, while considering that steering and leaning might vary depending on the cycling task being performed. Of 28 participants, 19 were given doses of alcohol up to 1.0‰ and 9 remained sober (control group). Breath alcohol concentration was measured. The participants repeated the cycling test track session five times (with each block lasting 35 minutes). The track session contained three different tasks: cycling slalom, straight, and slowly. Speed, yaw rate, and roll rate were assessed continuously. Yaw rate and roll rate were relatively sensitive for the different cycling tasks. The threshold level of the angular velocity measurements was related to the cycling task performed. Alcohol intoxication at 0.7‰ had a significant impact on performance. The rather simple measurements used can detect instability. Instability should be measured differently depending on the cycling task performed. The study represents a small step towards a safety system for cyclists.

High-order LG vortex Pr:YLF laser emitting in the visible wavelength range for the measurement of angular velocity

High-order LG vortex Pr:YLF laser emitting in the visible wavelength range for the measurement of angular velocity

Impact of Xsens Technology on Analysis of Gait Deviation in Pre- and Post-surgical Total Knee Arthroplasty Patient.

Introduction Osteoarthritis (OA) is a degenerative joint ailment that predominantly affects the knee and is most common in older adults. It destroys the surrounding tissues and cartilage. Following total knee arthroplasty (TKA), patients with end-stage knee OA can have long-term pain reduction and patient satisfaction, although certain functional limitations still exist. While TKA significantly reduces pain and improve function, many patients stillexperience abnormalities post-surgery, such as slower walking and reduced step-length. Gait analysis using technologies like the Xsens Motion Visualization and Navigation (MVN) system (Movella, Henderson, NV, USA)provides insights into these functional limitations, helping to assess knee mobility and predict changes in joint movements during activities. Methods Thirty-four people participated in a study done at the Centre for Advance Physiotherapy Education and Research, Ravi Nair Physiotherapy College, Wardha, both before and after total knee arthroplasty. Participants who ranged in age from 50 to 70 and had undergone unilateral TKA were included. Informed consent was obtained, and demographic data were collected. Participants walked a predetermined distance at their usual speed, and measurements of hip and knee angular velocity and center of mass were recorded for gait analysis. Result The study involved participants aged 50-70, with a mean age of 59.79 years and height ranging from 153.00 to 185.00 cm. Significant gait changes were noted pre- and post-total knee arthroplasty, including a decrease in walking speed from 0.72 to 0.55m/s and cadence from 105.06 to 82.86. Other parameters, such as step length and center of mass, also exhibited considerable differences, highlighting the impact of TKA on gait dynamics. Conclusion The study underscores the significant impact of total knee arthroplasty on gait mechanics and the value of advance of technologies likeXsens for assessing functional outcomes. While TKA provides pain relief and improved mobility, residual gait abnormalities persist, highlighting the need for tailored rehabilitation. Xsens technology enhances patient preparation, recovery tracking, and rehabilitation strategies, setting a new standard for gait analysis in orthopedic practice.

Velocity-free fixed-time attitude tracking fault-tolerant control for rigid spacecraft based on the homogeneity method

This paper examines the problem of fixed-time attitude tracking fault-tolerant for rigid spacecraft without angular velocity measurement, in the presence of uncertainties, external disturbances, and actuator faults. First, a fixed-time observer is established to obtain accurate estimates of the unmeasurable angular velocities, by applying a fixed-time observer, a fixed-time tracking control method is addressed to enable the tracking spacecraft to track the target spacecraft with time-varying attitude in a fixed time. A fixed-time output feedback attitude tracking controller is designed and the fixed time stability of the system is proved. In addition, the simulation results verify the effectiveness of the proposed control strategy.

Measurement of acceleration and angular velocity of particles during a 3D silo discharge

Accurate measurement of the three-dimensional (3D) movement of discrete particles is crucial for comprehending complex granular rheology in silos. In this paper, the acceleration and angular velocity of particles in 3D silos are measured by using a spherical detector based on inertial technology and magnetic positioning technology. The acceleration of particles is the largest in the center of silos, which suggest that the resistance generated by friction and extrusion is the smallest. Surprisingly, the angular velocity distribution follows lognormal function except for particles near the outlet. The correlation between acceleration and angular velocity is opposite in different flow regions. It reveals for the first time that the extent to which the resultant force on the particles affects their rotational motion is related to the flow pattern. These results have practical significance for regulating the granular flow pattern and optimizing the structural design of silos.

Polarization-based cyclic weak value metrology for angular-velocity measurement

Polarization-based cyclic weak value metrology for angular-velocity measurement

Kinematic criteria determining swing movement of world class dancesport athletes

PurposeThe aim of the study was to identify the distinguishing characteristics of the swing movement of the world’s top dancesport couples through kinematic variables.MethodsThe study involved six world-class and six intermediate dance couples. The couples were asked to execute three identical series of three natural turns of the figure in a Viennese Waltz, all being filmed as they danced to music. Six international experts evaluated all the trials of each couple from the point of view of the technical quality component based on the Absolute Judging System. A triaxial rotational angular velocity measurement (gyroscope) device was placed on the dorsal part of the pelvic girdle and on the posterior part of the thorax of each competitor.ResultsAn analysis of covariance demonstrated that regardless of the sports level, the maximum hip girdle angular rotation velocity in the forward swing movement performed by men was significantly related to the judging score achieved (F1,9 = 11.5; p < 0.05; ηp2 = 0.45).ConclusionsThe mean squares of the differences of the hip and thoracic spine angular rotation velocity signals were found to be a good criterion for evaluating the swing movement, which is related to the judges’ evaluation. The descriptions of the performance of complex rotational movements obtained in this study can find their application in the analysis, teaching, and evaluation of dance couples. This is one of the first studies in the literature that deals in detail with swing movement in sports dance.

Observer-based fault-tolerant fixed-time attitude tracking control for rigid spacecraft without angular velocity measurement

This paper investigates the problem of adaptive nonsingular fast terminal sliding mode fixed-time tracking control method for rigid spacecraft without angular velocity measurement. First, a novel fixed-time extended state observer is proposed to obtain accurate estimates of both unmeasurable angular velocities and integrated disturbance. Then, based on this sufficient qualification, an adaptive fast nonsingular terminal sliding mode controller is designed to make the state of the following spacecraft track a target spacecraft even when the tracking system has an actuator fault. Adaptive technology is introduced to compensate for the effect of observation error on the controller. Using the Lyapunov function and fixed-time property, it is proved that the control scheme can ensure that the attitude tracking error converges to the neighborhood of the origin in a fixed time and is independent of the initial conditions. Finally, numerical simulation examples are carried out to evaluate the effectiveness of the proposed fixed-time method.

A toroidal SAW gyroscope with focused IDTs for sensitivity enhancement

A surface acoustic wave (SAW) gyroscope measures the rate of rotational angular velocity by exploiting a phenomenon known as the SAW gyroscope effect. Such a gyroscope is a great candidate for application in harsh environments because of the simplification of the suspension vibration mechanism necessary for traditional microelectromechanical system (MEMS) gyroscopes. Here, for the first time, we propose a novel toroidal standing-wave-mode SAW gyroscope using focused interdigitated transducers (FIDTs). Unlike traditional SAW gyroscopes that use linear IDTs to generate surface acoustic waves, which cause beam deflection and result in energy dissipation, this study uses FIDTs to concentrate the SAW energy based on structural features, resulting in better focusing performance and increased SAW amplitude. The experimental results reveal that the sensitivity of the structure is 1.51 µV/(°/s), and the bias instability is 0.77°/s, which are improved by an order of magnitude compared to those of a traditional SAW gyroscope. Thus, the FIDT component can enhance the performance of the SAW gyroscope, demonstrating its superiority for angular velocity measurements. This work provides new insights into improving the sensitivity and performance of SAW gyroscopes.

Negative-imaginary-based spacecraft attitude tracking control using modified Rodrigues parameters

This paper investigates a counter-clock-wise input-output map about spacecraft attitude dynamics and kinematics using Modified Rodrigues Parameters. A gyro-free attitude control scheme is established by constructing a negative imaginary system for spacecraft attitude stabilization. Attitude tracking control scheme is also explored where the negative-imaginary-based controller has no need on the angular velocity measurements. Numerical simulations are presented to show the effectiveness of the proposed attitude control scheme.

Stationary Detection for Zero Velocity Update of IMU Based on the Vibrational FFT Feature of Land Vehicle

Stationary Detection for Zero Velocity Update of IMU Based on the Vibrational FFT Feature of Land Vehicle

A Model-Free Online Learning Control for Attitude Tracking of Quadrotors

This paper investigates the problem of attitude tracking in quadrotor unmanned aerial vehicles (UAVs) using a model-free online learning control (MFOLC) scheme. The attitude system, which is represented by unit quaternions, is considered in the presence of uncertain and unknown inertia parameters, time-varying external disturbances, and angular velocity measurement noise. A computationally low-cost control scheme consisting of a model-free baseline controller and a module capable of learning from previous control input is designed. The proposed controller does not require precise inertial parameters and does not involve feedforward terms that use these parameters and true system states. This ensures that the approach can protect the control effort from sensor noise as well as parameter uncertainty. We also show that all the signals in the closed-loop system are uniformly ultimately bounded. Comparative simulations and real-world experiments are conducted for validation, which demonstrate the effectiveness and fine performance of the proposed scheme.

Superconducting rotor drive method with integrated driving and alignment

The high-speed rotating superconducting rotor can be used as a high-precision inertial device to measure the angular position or angular velocity of the carrier. The mass eccentricity and spherical error of the superconducting rotor are the main error sources that affect the measurement accuracy. The more complex the structure of the superconducting rotor, the greater the mass eccentricity and spherical error caused by its production and assembly process are, and the lower the accuracy of its measurement of angular velocity. Based on this, in this work, an electromagnetic drive structure with a simple rotor structure is designed. And the torque generated by the stator on the superconducting rotor is studied through finite element method (FEM). The effects of the stator on vertical alignment and acceleration of the superconducting rotor are analyzed. Based on the research results of the superconducting rotor torque, a superconducting rotor drive method with integrated driving and vertical alignment is proposed, which achieves the driving and vertical alignment functions simultaneously through the stator coil, and corresponding stator control timing is designed. Finally, the torque distribution in the driving process of the proposed driving method is analyzed, and the driving effect is quantitatively analyzed based on the response characteristics of the stator system. The time for the superconducting rotor to be accelerated to 50 Hz under different conditions is calculated. The results show that the designed driving electromagnetic structure and the proposed integrated driving method of vertical alignment and driving can be used for vertical aligning and driving the superconducting rotor. The research results provide a reference for further optimizing the superconducting rotor structure and driving methods of superconducting rotors.

Classification of Aortic Stenosis Patients via ECG-Independent Multi-Site Measurements of Cardiac-Induced Accelerations and Angular Velocities at the Skin Level

Classification of Aortic Stenosis Patients via ECG-Independent Multi-Site Measurements of Cardiac-Induced Accelerations and Angular Velocities at the Skin Level

Industrial analysis of gyro stability and precision assembly

Abstract Gyro is a new type of widely used micro-inertial sensor, which can realize high-precision, small-size, and anti-interference angular velocity measurement and is widely used in aerospace, platform drilling, autonomous driving, wearable devices, and cell phones. The study first analyzes the influence of the angle of control torque on the stability of the gyro and deduces the relationship between the gyro rotational inertia, spin angular velocity, feed angular velocity, and stability. Then, through the research of industrial gyro products research status, the factors affecting the precision of the gyro elaborated on the key technologies that need to be broken through in the process of gyro precision assembly and combined with the sequential stacking method to realize the gyro in the industrial close assembly. The results show that both the shape factor and scale factor are the influencing factors of gyro stability. The shape and position error of each part, as well as the coupling of the error, cause the uneven force on the motor shaft, the local stress concentration, and, therefore, local deformation, which ultimately leads to the offset of the motor shaft center, and the influence of the shape and position coupling error on the assembly precision of the gyro.

Adaptive Neural Network Stochastic-Filter-Based Controller for Attitude Tracking With Disturbance Rejection.

This article proposes a real-time neural network (NN) stochastic filter-based controller on the Lie group of the special orthogonal group [Formula: see text] as a novel approach to the attitude tracking problem. The introduced solution consists of two parts: a filter and a controller. First, an adaptive NN-based stochastic filter is proposed, which estimates attitude components and dynamics using measurements supplied by onboard sensors directly. The filter design accounts for measurement uncertainties inherent to the attitude dynamics, namely, unknown bias and noise corrupting angular velocity measurements. The closed-loop signals of the proposed NN-based stochastic filter have been shown to be semiglobally uniformly ultimately bounded (SGUUB). Second, a novel control law on [Formula: see text] coupled with the proposed estimator is presented. The control law addresses unknown disturbances. In addition, the closed-loop signals of the proposed filter-based controller have been shown to be SGUUB. The proposed approach offers robust tracking performance by supplying the required control signal given data extracted from low-cost inertial measurement units. While the filter-based controller is presented in continuous form, the discrete implementation is also presented. In addition, the unit-quaternion form of the proposed approach is given. The effectiveness and robustness of the proposed filter-based controller are demonstrated using its discrete form and considering low sampling rate, high initialization error, high level of measurement uncertainties, and unknown disturbances.

Design and development of MEMS quartz gyroscope measurement and control circuit with automatic gain control principle

Angular velocity is a very important measurement parameter for autonomous driving and industrial applications. The design of MEMS quartz gyro measurement and control circuit has always been the key to restricting the measurement angular velocity performance of gyro system. This paper introduces the application-specific integrated circuit (ASIC) design and implementation of a MEMS quartz gyro measurement and control circuit for angular velocity measurement. The designed nonlinear multiplier can use a square wave to drive the gyro’s sensitive structure at the beginning of gyro start-up, thereby reducing the gyro power-up time. The drive circuit replaces the PLL with an automatic gain control unit composed of peak detection and proportional integration (PI) controller, which makes the MEMS gyro system have good robustness. First, SIMULINK is used to model and simulate the MEMS gyroscope system-level model, which illustrates the feasibility of the drive circuit design scheme. Then, the operating principle of the drive loop is analyzed, and the design of the key circuit modules of the measurement and control circuit is introduced. Finally, the performance of the gyroscope drive and detection circuit is experimentally tested, the amplitude and frequency uncertainty of the gyroscope drive circuit are evaluated, and the bias instability and nonlinearity of the gyroscope are tested, the experiment results show that the gyroscope has good performance.

Dynamic segmental kinematics of the lumbar spine during diagnostic movements.

Background: In vivo measurements of segmental-level kinematics are a promising avenue for better understanding the relationship between pain and its underlying, multi-factorial basis. To date, the bulk of the reported segmental-level motion has been restricted to single plane motions. Methods: The present work implemented a novel marker set used with an optical motion capture system to non-invasively measure dynamic, 3D in vivo segmental kinematics of the lower spine in a laboratory setting. Lumbar spinal kinematics were measured for 28 subjects during 17 diagnostic movements. Results: Overall regional range of motion data and lumbar angular velocity measurement were consistent with previously published studies. Key findings from the work included measurement of differences in ascending versus descending segmental velocities during functional movements and observations of motion coupling paradigms in the lumbar spinal segments. Conclusion: The work contributes to the task of establishing a baseline of segmental lumbar movement patterns in an asymptomatic cohort, which serves as a necessary pre-requisite for identifying pathological and symptomatic deviations from the baseline.

Robust measurement of angular velocity based on rotational Doppler effect in misaligned illumination

The discovery of the rotational Doppler effect (RDE) provides opportunities to achieve fast, accurate, and contactless measurement of angular velocity. As the RDE signal is sensitive to the illumination light and its scattering characteristic, how to effectively extract the angular velocity of a detected target becomes one of the key difficulties in this measurement technique. Here, we put forward a scattering modified RDE model to fully understand the frequency-domain behavior of an RDE signal in misaligned illumination. A robust strategy based on the peak-to-peak intervals in a wideband spectrum of the RDE signal is demonstrated to acquire accurate angular velocity, without strict requirement to the alignment of illumination and roughness of the detected surface. Furthermore, the feasibility to extract the spin angular velocity from a composite motion of spin and translation is discussed.