Angular Velocity Sensors Research Articles

Fault Tolerant Control in Underwater Vehicles

The article discusses the problem of adaptive system synthesis to provide the detection, estimation, and elimination of the negative consequences of faults in the thrusters of underwater robots and deviations of their parameters. For this purpose, an approach consisting of three stages is proposed. At the first stage, based on a bank of diagnostic observers, deviations of the thruster parameters from their nominal values or the occurrence of errors in the readings of its sensors are detected. At the second stage, the magnitudes of the detected deviations and errors are estimated using sliding mode observers. To estimate not only single but also multiple faults, the additional sliding mode observers are used. At the third stage, a control signal is generated to retain the basic dynamic properties of the thruster based on the estimated magnitudes of deviations and errors. Thus, the main contribution of this paper is designing the systems compensating for the consequences of faults occurring in the thrusters of the UR and errors in the readings of the angular velocity sensors. This avoids reducing the accuracy of movement along specified trajectories, as well as preventing accidents that could lead to the loss of the vehicle. The operability and efficiency of the proposed systems were tested using computer simulations and experimental studies on an electro-mechanical stand.

Spatiotemporal understanding of behaviors of laying hens using wearable inertial sensors

Automatic detection of behaviors and locations has been increasingly needed in the management of non-cage systems where hen behaviors are highly diverse and active. Here we show a technology to spatiotemporally understand behaviors using a wearable inertial sensor, containing a three-axis accelerometer and three-axis angular velocity sensor (i.e., gyroscope), and a marker. Using supervised machine learning, we first developed a tool that automatically classified and counted 11 behaviors, including comfort behaviors such as head scratching and tail-wagging with small movements as well as dust-bathing with dynamic movements. As expected, these behaviors were observed more frequently in floor pens than in conventional cages (all P < 0.01). We also spatially mapped the behaviors in floor pens and visualized the behavioral frequency in each resource by detecting the colored markers on the sensor. Furthermore, using the time-series information included in the sensor data, we analyzed the behavioral transition from one behavior to another. The behavioral transitions were more complex in floor pens, and the number was higher in body shaking, tail-wagging, resting, litter scratching, dust-bathing, preening, and moving in floor pens than in conventional cages (all P < 0.05). Our tools presented deeper insights into where and what hens behaved and also suggested that connectivity between behaviors, as well as observing the frequency of a behavior, can be an important indicator for welfare assessment in laying hens.

A novel temperature drift compensation method based on LSTM for NMR sensor

Nuclear Magnetic Resonance (NMR) sensors have become one of the best choices for angular velocity sensors in future Inertial Navigation Systems (INS) due to their small size and high precision. The performance of NMR sensors can be affected by temperature changes, resulting in temperature drift. Therefore, temperature compensation is essential. Accurate temperature compensation is challenging due to the lack of direct temperature observations in the core sensitive area (cell) and the complex temperature drift model. Considering the time correlation of temperatures inside and outside the cell, a new temperature drift compensation method based on the Long-Short Term Memory (LSTM) network is proposed. The memory characteristics of the LSTM enable it to fully utilize current and previous data to learn complex models. The main contributions of this study are as follows: (1) the mechanism of temperature drift in NMR sensors was analyzed; (2) a multi-time scale input–output model for temperature changes, temperature change rates, and ambient temperature versus sensor output bias was established; (3) a temperature drift model identification method based on LSTM was designed. Experimental results show that, compared to traditional polynomial fitting and memory-free methods, the proposed method improves temperature compensation accuracy by 26.0% to 47.0%. This method effectively reduces the adverse impact of temperature changes on the NMR sensor.

GINGER data analysis for seismology

Since several years, the ring laser gyroscope GINGERINO is operative inside the underground Gran Sasso laboratory. It monitors on a continuous basis the local Earth angular velocity in the horizontal plane. It provides unique information for geophysics in general, being one of the few top sensitivity angular velocity sensors. The present paper describes the analysis procedure developed for the data uploaded on the EIDA data base, suitable for seismological investigation in the frequency window 100 s up to 100 Hz. Typical errors and data quality will be discussed. This work is part of the data analysis tools under development for the GINGER project, a ring laser array, part of the UGSS (Underground Gran Sasso Seismology) multi components array at present in construction inside the Gran Sasso laboratory.

Study on Mathematical Models for Precise Estimation of Tire–Road Friction Coefficient of Distributed Drive Electric Vehicles Based on Sensorless Control of the Permanent Magnet Synchronous Motor

In order to reduce the use of wheel angular velocity sensors and improve the estimation accuracy and robustness of the tire–road friction coefficient (TRFC) in non-Gaussian noise environments, this paper proposes a sensorless control-based distributed drive electric vehicle TRFC estimation algorithm using a permanent magnet synchronous motor (PMSM). The algorithm replaces the wheel angular velocity signal with the rotor speed signal obtained from the sensorless control of the PMSM. Firstly, a seven-degree-of-freedom vehicle dynamics model and a mathematical model of the PMSM are established, and the maximum correntropy singular value decomposition generalized high-degree cubature Kalman filter algorithm (MCSVDGHCKF) is derived. Secondly, a sensorless control system of a PMSM based on the MCSVDGHCKF algorithm is established to estimate the rotor speed and position of the PMSM, and its effectiveness is verified. Finally, the feasibility of the algorithm for TRFC estimation in non-Gaussian noise is demonstrated through simulation experiments, the Root Mean Square Error (RMSE) of TRFC estimates for the right front wheel and the left rear wheel were reduced by at least 41.36% and 40.63%, respectively. The results show that the MCSVDGHCKF has a higher accuracy and stronger robustness compared to the maximum correntropy high-degree cubature Kalman filter (MCHCKF), singular value decomposition generalized high-degree cubature Kalman filter (SVDGHCKF), and high-degree cubature Kalman filter (HCKF).

A Curiosity Estimation in Storytelling with Picture Books for Children Using Wearable Sensors.

Storytelling is one of the most important learning activities for children since reading aloud from a picture book stimulates children's curiosity, emotional development, and imagination. For effective education, the procedures for storytelling activities need to be improved according to the children's level of curiosity. However, young children are not able to complete questionnaires, making it difficult to analyze their level of interest. This paper proposes a method to estimate children's curiosity in picture book reading activities at five levels by recognizing children's behavior using acceleration and angular velocity sensors placed on their heads. We investigated the relationship between children's behaviors and their levels of curiosity, listed all observed behaviors, and clarified the behavior for estimating curiosity. Furthermore, we conducted experiments using motion sensors to estimate these behaviors and confirmed that the accuracy of estimating curiosity from sensor data is approximately 72%.

The Xe isotope nuclear resonance frequency shift of NMR angular velocity sensors due to transverse gradient magnetic fields

The nuclear magnetic resonance (NMR) angular velocity sensor detects angular velocity by measuring the shift in the nuclear spin precession frequency, which is of fundamental interest. Recent studies have revealed the parameter dependency of nuclei frequency shifts induced by non-uniformly distributed polarized pump beams, temperature, and magnetic field properties. In this study, we investigated the effect of the linear transverse gradient magnetic field on the frequency ratio shift of the Xe isotope nuclear resonance frequency in the NMR sensors. A theoretical analysis method was proposed based on the Fermi contact interaction in atomic polarization and the spin-diffusion relaxation of 129Xe and 131Xe nuclei. The frequency ratio shift of the Xe isotope under different x-axis gradient magnetic fields was measured experimentally. Furthermore, we eliminated the equivalent residual magnetic field through a feedback system and compensated for the original gradient magnetic field in the system, which contributed to accurately revealing the frequency shift induced by the magnetic field gradient. The results indicate that the frequency ratio shift of the Xe isotope is proportional to the strength of the second-order linear transverse gradient magnetic field. This study provides a reference for the analysis and evaluation of the presence of the gradient magnetic field in the NMR angular velocity sensor.

Analysis and suppression of the Rb resonance frequency error in NMR angular velocity sensor

The nuclear magnetic resonance (NMR) angular velocity sensor has the potential for high precision measurement in small volumes, which measures the 129Xe and 131Xe precession frequencies to obtain the angular velocity with respect to an inertial reference frame. One of the key challenges in frequency measurement is the long-term stability of the measured signal phase. The measured signal is acquired by applying a carrier magnetic field along the z-axis and demodulating the carrier signal at its frequency, which is typically fixed. However, fluctuations in light shifts and static magnetic fields can lead to instabilities in the Rb resonance frequency, consequently impacting the measurements of phase and precession frequencies of 129Xe and 131Xe. To address this issue, an analysis of the Rb resonance frequency error is conducted, and a suppression scheme based on carrier frequency correction is provided. This scheme can mitigate the effect of Rb resonance frequency fluctuations without further suppressing fluctuations of light shifts and static magnetic fields. The experiment demonstrates a 53.5 % reduction in the precession frequency error between 129Xe and 131Xe and a 59.0 % decrease in bias instability. This scheme can improve the long-term stability of 129Xe and 131Xe precession frequency measurements, thereby enhancing the performance of the NMR angular velocity sensor.

Trajectory planning and control strategy optimization design of double electric cylinder erecting device

The transition of the rocket from a horizontal to an erect state before its launch on the offshore platform is a crucial stage. Compared with erecting the rocket on the ground, higher servo control and synchronization accuracy are required for erecting it on the offshore platform. Most rocket erecting devices on offshore platforms rely on hydraulic drive systems, posing challenges due to their lower servo control accuracy and difficulties in achieving high-precision synchronization. The erecting process, trajectory planning, control system, and control strategies of rockets driven by a double electric cylinder erecting device are studied, aiming at the requirement of erecting rocket devices on offshore platforms. This paper commences by establishing the kinematic model of erecting the rocket with a double electric cylinder erecting device. It delves into the process and trajectory of the erection rocket with a double electric cylinder erecting device. Subsequently, the focus shifts toward designing the control system, while inclination and angular velocity sensors monitor the erection process. Finally, designing and demonstrating control strategies for a double electric cylinder erecting device, three different control strategies, master control, master-slave control, and cross-coupling control, are analyzed, and the cross-coupling control strategy is selected as the control strategy of the double electric cylinder offshore platform rocket erecting device.

Design of a Vehicle Fatigue Driving Detection System Based on Multiple Signals

In recent years, traffic accidents have occurred frequently, and most of them are related to the level of fatigue of drivers. In order to avoid the dangers of fatigue driving, this article judges whether the driver is in a fatigued state by analyzing the changes in pressure, angle, and distance during driving, so as to remind the driver to reduce the probability of accidents. In terms of hardware, we use the AT89C51 microcontroller as the main control unit, and configure infrared sensors, ultrasonic sensors, angular velocity sensors, and pressure sensors to detect the physical state of the driver. In terms of software, we use C language to write code and optimize and compile it through Keil software. The system can display the detected data on the LCD display screen and send an alarm at the same time.

Solution to the problem of detecting a malfunction of the position sensor of small spacecraft

The classic scheme for constructing a modern system for controlling the parameters of the angular motion of a spacecraft involves the use of high-precision gyroscopes, periodically adjusted according to the readings of optoelectronic devices. The most widely used in orientation and navigation systems are precision angular velocity sensors and gyroscopes on an electrostatic suspension, which determine the angles of rotation of the aircraft around its center of mass; Angular and linear accelerometers are also used, mounted in a certain way on the body of the aircraft.

Helium damping characteristics of rotating superconducting rotor

The superconducting rotor magnetic levitation device can be used to make an angular velocity sensor, and the high-speed rotating superconducting rotor is the basis for achieving high-precision measurement of the superconducting rotor magnetic levitation device. The heat loss and radial mass eccentricity of the superconducting rotor can cause thermal quenching and resonance in the driving process, which is unfavorable to the driving process of the superconducting rotor. Therefore, it is necessary to maintain a certain quantity of helium gas in the superconducting cavity in the driving process, to transfer the heat generated by the driving process and avoid its resonance. But helium gas also has a drag torque on the rotating superconducting rotor, affecting the driving process of the superconducting rotor. Based on this, the drag torque of the helium on the rotating superconducting rotor is studied. Firstly, the Van der Waals equation is introduced to analyze the properties of low-temperature helium, and a method of studying the drag effect of low-temperature helium on the rotating superconducting rotor is proposed based on Reynolds law and Stoke’s first problem. Then, an experiment on superconducting rotor speed attenuation is conducted to verify the proposed analysis method. Based on the finite element method, the driving electromagnetic structure and driving torque of the superconducting rotor are analyzed. Finally, the influence of helium on the driving process of the superconducting rotor is investigated, including critical driving speed, acceleration time of the superconducting rotor, and frictional heat of the helium on the superconducting rotor. The research results further enrich the study of the drag torque of low-temperature gases on rotating superconductors, providing a reference for further optimizing the driving process of superconducting rotors.

Orientation Quaternion Norm Correction in SINS Algorithms: Calculation Normalization Schemes and Their Efficiency

The problem of correcting the norm of the computed orientation quaternion in the algorithms for the operation of strapdown inertial navigation systems is considered. Two existing approaches to the correction process are considered, the first approach is to normalize the rotation quaternion at the computation cycle, the second approach is to normalize the resulting quaternion. 5 well-known calculation schemes for norm correction are given. To simulate the test motion, we used an analytical quaternion kinematic rotation model based on a sequence of three rotations corresponding to the Krylov angles. The case of linear dependence of elementary rotation angles on time is considered. The model provides analytical representation of the projections of the angular velocity vector of the rigid body on the associated axes and the corresponding quasi-coordinates on the calculation cycle. The results of numerical simulation of the reference motion for a given set of frequencies are presented as dependences of the projections of the angular velocity vector of the rigid body on time and the constructed trajectories in the configuration space of the orientation parameters.&#x0D; To determine the rotation quaternion on a cycle, the Miller algorithm was used, which makes it possible to obtain an increase in the orientation vector based on ideal information from the angular velocity sensors in the form of quasi-coordinates. The transformation into a rotation quaternion occurs with the help of the corresponding expansions of the trigonometric functions of the true rotation angle (modulus of the orientation vector) in a series.&#x0D; Based on a numerical experiment, it is shown that the best result of correcting the norm of the calculated quaternion in the sense of the minimum error of the norm is given by one of the finite normalization schemes, for which there is no division operation and ensures the stability of the norm correction in time. The results of numerical simulation of the model rotational motion of a rigid body and the development of schemes for correcting the norm of the calculated orientation quaternion are presented.&#x0D; Keywords: orientation quaternion, Miller's orientation algorithm, SINS, norm error, computational drift, analytical reference model, quasi-coordinates, numerical simulation.

Fixed-time fault-tolerant attitude control for flexible spacecraft without angular velocity sensor

This paper deals with the appealing problem of fixed-time fault-tolerant attitude control, using attitude-information-only, for a flexible spacecraft under the influence of inertial parametric variations, external disturbances, and multiple actuator faults while suppressing the flexible appendages’ vibrations without using additional sensors or smart vibration suppression actuators. First, an adaptive fixed-time model-free observer (AFTMFO) is designed, using the attitude information, for rapid estimation of unavailable angular velocity. A novel adaptive continuous control is then synthesized based on an anti-unwinding fast fixed-time nonsingular sliding surface (AFFTNSS), utilizing variable gains in both the control law and sliding surface; that simultaneously alleviates the chattering but also improves the convergence speed when compared to existing fixed-time approaches. The proposed scheme offers superior performance characteristics such as velocity sensor-free fixed-time attitude maneuvering with high pointing accuracy, fault tolerance, vibration suppression, nonsingular and chattering-free control. The spacecraft can carry out the coveted control objective in a predeterminable time independent of the knowledge of initial states while overcoming the unwinding effect to reduce the control effort and time. The fixed-time closed-loop stability of the proposed scheme is corroborated via Lyapunov techniques. Finally, a comparative simulation analysis with the existing results elucidated the proposed scheme’s efficacy.

The method of inertial-visual orientation of the aircraft

The article proposes a method for determining the orientation angles of an aerial vehicle based on information from an optical camera and a triad of angular velocity sensors. The basic formulae necessary for determining the orientation angles and calculating the size of the image area for processing are given. Simulation of the operation of the algorithm for determining the pitch angle of the airial vehicle on real images was carried out. At the same time, the errors of sensors were taken into account. The use of angular velocity sensors of low and medium accuracy class was considered. The advantages of the method are the absence of the need to detect the horizon line and low requirements for the navigation computer.

Versatile Gyroinclinometer Based on a Single Axis Angular Rate Sensor

Introduction. Currently, the versatility and reliability of gyroscopic inclinometers (GI), more than accuracy, determine their configuration and design. Imperative conditions for versatility include a diameter of 42…44.5 mm and a combination of point and continuous survey modes. Reliability is primarily determined by the robustness of the main elements. The fundamental parameter is adaptability to the trajectory, in other words, equal accuracy in the operating range of zenith angles, which determines the choice of orientation of the angular velocity sensors (ARS) with incomplete (&lt; 3) number of their axis. Presently, biaxial dynamically tuned gyroscopes (DNG) are widely used due to their dimension and accuracy criteria; however, their elastic suspension gradually degrades as a result of frequent sidetracking operations (from previously drilled ones) accompanied by high-intensity impacts.Aim. To develop an inexpensive versatile GI that maintains a balance between shock resistance and accuracy (com[1]parable to fiber-optic ARS) based on a single-axis vibrating ring gyroscope (VRG) with an induction-type resonator made using MEMS technology.Materials and methods. The method of multi-position compassing with a single uniaxial ARS was implemented by transition from simultaneous biaxial measurements to uniaxial measurements in five successive positions of the frame (through 90°) along the toolface angle. Experimental data on the drifts of the selected VRG allow statistical methods to be used to construct an Allan-variance plot to confirm that the proposed method does not increase the total compassing time compared to the basic one. The continuous mode of such a GI, studied by solving differential equations, requires holding the input axis of the ARS near the apsidal plane using the same rotating frame.Results. The obtained ratios confirm that the performance characteristics of a GI with a uniaxial ARS approximately correspond to the conventional biaxial scheme. These conclusions were also confirmed by the mathematical modeling of a survey of a typical oil and gas well.Conclusion. The described GI containing a single ARS with indirect stabilization of the input axis is the result of a consistent development of the approach to the use of incomplete information

Research on the SAW Gyroscopic Effect in a Double-Layer Substrate Structure Incorporating Non-Piezoelectric Materials.

The SAW (surface acoustic wave) gyroscopic effect is a key parameter that reflects the sensitivity performance of SAW angular velocity sensors. This study found that adding a layer of non-piezoelectric material with a lower reflection coefficient than that of the upper-layer material below the piezoelectric substrate to form a double-layer structure significantly enhanced the SAW gyroscopic effect, and the smaller the reflection coefficient of the lower-layer material, the stronger the SAW gyroscopic effect, with values being reached that were two to three times those with single-layer substrate structures. This was confirmed using a three-dimensional model, and the experimental results also showed that the thickness of the piezoelectric layer and the type of the lower-layer material also had a significant impact on the SAW gyroscopic effect. This novel discovery will pave the way for the future development of SAW angular velocity sensors.

Determination of regularities that influence the acoustic pressure and accuracy of inertial sensors

This study investigated the influence of high-intensity acoustic radiation on the elements of a navigation system, namely, the angular velocity sensor DUSU-2AS. The measurement error of the device under the influence of acoustic pressure is determined. High-intensity acoustic radiation causes measurement errors that are greater than the sensitivity threshold of the device. Numerical analyses of the degree of influence when the penetrating acoustic radiation is 140 dB demonstrate that the maximum bending vibration is 4.471 µm. Computational models for calculating the diffraction of the sound waves are proposed and tested. This study assessed the influence degree of penetrating acoustic radiation on inertial sensors, as well as the degree of danger of technological risks such as resonance manifestations. Acoustic radiation that passes into a device generates many vibration modes on the surface and can have a considerable effect on the precision of inertial sensors.

Fault diagnosis research of laser gyroscope based on optimized-kernel extreme learning machine

Traditional diagnostic models for laser gyroscopes, widely which are commonly employed as high-precision angular velocity sensors in aerospace applications, often encounter challenges in terms of reliability and accuracy. These challenges arise from difficulties in feature extraction, high computational costs, and lengthy training times. In light of these challenges, the present study proposes a new method for diagnosing faults in laser gyroscopes using the Kernel Extreme Learning Machine (KELM). Specifically, the proposed method utilizes Wavelet Packet Decomposition (WPD) to efficiently extract features from the laser gyroscope signal, which are then used as input for our diagnostic model. Furthermore, the KELM model is trained for fault diagnosis. Afterward, we utilize the Improved Dung Beetle Optimizer (IDBO) algorithm to optimize its parameters for improved optimization performance. According to the experimental results, our proposed IDBO-KELM model demonstrates a 3.68% improvement in diagnostic accuracy compared to traditional approaches. Additionally, it offers the advantages of shorter training time and increased precision.

Adaptive Capture Control of a Continuum Manipulator With Self-Powered Sensors

Perception is an essential component of an intelligent autonomous system. However, the traditional sensors used in robotics and industrial are limited when considering high mobility, wide distribution, and possible wireless operation of the sensors in sensor networks. The self-powered sensing solves the most shackling issue in the current sensing field, thus enabling many previously unattainable application scenarios. In this paper, a novel variable-length continuum manipulator with self-powered sensors is designed, and an adaptive capture control scheme based on deep learning prediction is proposed for the envelope grasp of a fixed cylinder target and the hook grasp of a ring target moving in a small range. First, adaptive capture parameters of the manipulator are generated according to a target’s size and position. Then, deep neural networks are utilized to accurately predict the bending angle of the manipulator with a large displacement motion at the tip of the continuum manipulator. Finally, based on the feedback data from the driving motor’s built-in angular velocity sensor on the continuum manipulator, a set of capture criteria are presented to identify the envelope and capture states of the target. The capture experimental results on a prototype reveal that the generated parameters highly match the targets. The prediction method’s accuracy is higher than that of conventional feedforward neural networks. The capture criteria based on the feedback data from driving motor’s built-in angular velocity sensor can correctly identify the target capture states. In additional, the future research of the adaptive capture control based on self-powered sensors is discussed.