Moment Sensor Research Articles

A Rod-Type Passive and Wireless Torque and Bending Moment Sensor Working in a Self-Decoupled Mode

A Rod-Type Passive and Wireless Torque and Bending Moment Sensor Working in a Self-Decoupled Mode

RETRACTED: Data–Driven Adaptive Fault–Tolerant Control for Floating Offshore Wind Turbines

Floating offshore wind turbines have increased in popularity owing to their adaptability for deep-water applications and high power generation efficiency. The control of floating offshore wind turbines, on the other hand, is very complex. The main challenges are the difficulty in precisely modelling floating offshore wind turbines and the higher failure rate of components. As a consequence, this study proposes a model-free adaptive fault-tolerant control system for blade root moment sensor failures. A model-free adaptive control approach is used to construct an individual pitch controller and a fault compensation to avoid mathematical modelling of floating offshore wind turbines. The proposed fault-tolerant control technique removes the need for fault detection and isolation by converting the fault dynamic compensation process into a real-time control issue for nonlinear systems. The fatigue, aerodynamics, structures, and turbulence code simulates and tests the proposed control strategy, and the results show that the proposed strategy can not only keep the wheel bearing load balanced but also reduce the movement of the floating platform and significantly reduce the bearing load of the floating offshore wind turbines. Furthermore, the output power is closer to the rated power, proving the strategy’s high fault tolerance in the face of repeated blade root moment sensor faults.

Forces and moments generated during extrusion of a maxillary central incisor with clear aligners: an in vitro study

ObjectiveTo assess the possibility of extrusion of a maxillary central incisor with the use of buccal and lingual pressure columns in the absence of attachments, and to evaluate the forces and moments experienced by the teeth using both thermoformed and 3D-printed clear aligners.Materials and methodsA three-axis force and moment sensor (Aidin Robotics, Anyang, South Korea) was used to measure the forces and moments during extrusion of an upper left central incisor (UL1) and any forces experienced by the upper right central incisor (UR1) using thermoformed aligners and 3D-printed aligners. For the thermoformed aligners, the materials used were ATMOS® (American Orthodontics, Sheboygan, WI) and Zendura FLX® (Bay Materials LLC, Fremont, CA). 3D-printed aligners were fabricated using TC-85 clear photocurable resin (Graphy Inc., Seoul, South Korea). For each material type, three conditions were tested: Group 1: No attachment or pressure columns (control); Group 2: Attachment only; and Group 3: Pressure columns only. Each group was planned for 0.5 mm of extrusion on the UL1.ResultsAll force readings collected demonstrated statistically significant differences when compared by materials and when compared by groups, with a P value of < 0.001. In the absence of attachment or pressure columns (Group 1), ATMOS® and TC-85 groups exerted extrusive force on the UL1. However, significantly lower forces and moments were exerted by the TC-85 group in comparison to the ATMOS® and Zendura FLX® groups. In the presence of attachment (Group 2), all three ATMOS®, Zendura FLX® and TC-85 groups exerted extrusive force on the UL1, with the TA group showing different directions of faciolingual force, mesiodistal force and faciolingual inclination on the UR1 when compared to the other two thermoformed groups. Whereas in the presence of pressure columns (Group 3), only the TC-85 3D-printed aligner group exerted extrusive force. Thermoformed aligners generated significantly higher mean forces and moments than 3D-printed aligners. Significant levels of unintended forces and moments were present in all groups.ConclusionsForce levels generated during extrusion with clear aligners are significantly lower with those 3D-printed using TC-85 than with those thermoformed using ATMOS® or Zendura FLX®. Attachments consistently generated extrusive forces, and may be an effective adjunct in achieving extrusion of incisors. Extrusion may be achieved without the use of attachments by utilizing pressure columns in 3D-printed aligners using TC-85. While different strategies can generate extrusive forces, there are significant unintended forces and moments.

그리퍼 내에서 물체의 위치를 인지하기 위한 그리퍼의 5축 힘/모멘트센서 개발

In this paper, we describe the development of a 5-axis force/moment sensor of an intelligent gripper designed to grasp the weight of an unknown object and the position of the object in the gripper. The 5-axis force/moment sensor consists of an Fx force sensor, Fy force sensor, and Fz force sensor to measure weight, along with an Mx moment sensor and Mz moment sensor to determine the position of an object in the gripper. These sensors are all built within a single body. Each sensor sensing part of the 5-axis force/moment sensor was newly modeled and custom designed using software, and each sensor was manufactured by attaching a strain gauge. The results of the characteristic test of the fabricated 5-axis force/moment sensor showed that the rated output error was within 0.1%, the reproducibility error was within 0.05%, and the nonlinearity error was within 0.04%. Therefore, the 5-axis force/moment sensor developed in this paper can be attached to an intelligent gripper and be used to grasp the weight of an unknown object as well as the position of the object in the gripper.

TWO-GYROSCOPIC SENSITIVE ELEMENT OF THE STABILIZATION COMPLEX

The proposed two-gyroscopic SE is designed to measure acceleration and belongs to the area of acceleration measurements on a moving base and can be used in stabilization systems. The purpose of the article is to increase the accuracy of acceleration determination. To do this, it is necessary to eliminate methodical errors of gyroscopic moments-obstacle from the cross angular velocities of the base and from the angular velocity of the Earth's rotation. The proposed two-gyro SE consists of a three-stage gyroscope located in the inner and outer frames, equipped with an inter-frame correction system, which includes an angle sensor located on the axis of the inner frame of the gyroscope, the output of which is connected to a moment sensor located on the axis of the outer frame. What is new in the two-gyro SE stabilizer is the application on the axis of the inner frame of the gyroscope with the possibility of rotating the rotor in the opposite direction of the main gyroscope, equipped with an inter frame correction system, which includes an electric angle sensor located on the axis of the inner frame of the gyroscope, to the output of which the control winding of the electric moment sensor is connected. Located on the axis of the outer frame, and both gyroscopes are equipped with two additional angle sensors located on the axes of the outer frames, the outputs of which are connected to two additional moment sensors located on one axis of the inner frame, the centers of gravity of the two three-stage gyroscopes are equally shifted to one side along the axes of rotation gyroscope rotors relative to the axes of the outer frames.

A Moment and Torque Sensor With a Birfield-Type Structure, Using a Mechanically Self-Decoupled Method

A moment and torque sensor with a birfield-type structure using a mechanically self-decoupled method was proposed, analyzed, fabricated, and tested. The self-decoupling operation was achieved by arranging the moment and torque transmission along different routes by designing a birfield-type mechanical structure. Two pieces of magnetostrictive material 2826MB were pasted on the sensitive parts along the moment and torque transmitting route for detection purposes. Then, the moment and torque were measured on the sensitive parts and were found not to affect each other. The sensor can realize noncontact and dynamic detection based on the Villari effect. Experiments were conducted to test the performance of the sensor. Experimental results showed that the sensor had a good self-decoupling performance, with an error less than 1.10%. The sensor had an excellent linear performance. The sensor can also work dynamically with an error less than 3.54%. Based on the uncertainty analysis, the total uncertainty of the sensor is 0.015, which ensures the stability in multiple precision measurements. Furthermore, the sensor displayed advantages of working passively, wirelessly. All these advantages enable the sensor potential applications in cutting tools, sealed gearboxes, etc.

Target Localization and Sensor Movement Trajectory Planning with Bearing-Only Measurements in Three Dimensional Space

In order to improve the accuracy of bearing-only localization in three dimensional (3D) space, this paper proposes a novel bias compensation method and a new single-sensor maneuvering trajectory algorithm, respectively. Compared with traditional methods, the bias compensation method estimates the unknown variance of bearing noise consistently, which is utilized in pseudo-linear target localization to achieve higher precision. The sensor maneuvering algorithm designs the next moment sensor location in consideration of all the past sensor locations, unlike other approaches that only consider finite past locations. Research shows that the trajectories generated by our algorithm have greater Fisher information matrix (FIM) determinants and better localization accuracy.

Hybrid Force and Motion Control of a Three-Dimensional Flexible Robot Considering Measurement Noises

This work addresses the end-effector trajectory-tracking force and motion control of a three-dimensional three-link robot considering measurement noises. The last two links of the manipulator are considered as structurally flexible. An absolute coordinate approach is used while obtaining the dynamic equations to avoid complex dynamic equations. In this approach, each link is modeled as if there is no connection between the links. Then, joint connections are expressed as constraint equations. After that, these constraint equations are used in dynamic equations to decrease the number of equations. Then, the resulting dynamic equations are transformed into a form which is suitable for controller design. Furthermore, the dynamic equations are divided as pseudostatic equilibrium and deviation equations. The control torques resulting from the pseudostatic equilibrium and the elastic deflections are obtained easily as the solution of algebraic equations. On the other hand, the control torques corresponding to the deviations are obtained without any linearization. Encoders, strain gauges, position sensors and force and moment sensors are required for measurements. Low pass filters are considered for the sensors. For the crossover frequencies of the sensors, low and high values are chosen to observe the filtering effect on the robot output.

A Semi-Modularization Moment, Axial Force and Torque Force Sensor, From Concept to Realization

A modular design concept for multidimensional sensors that does not lead to dimension waste was propounded. The new modular design increased the sensor dimensionality by expanding additional modules according to practical demands. A moment, axial force, and torque force sensor based on a modular design operating in a self-decoupled, passive, and wireless manner was proposed, designed, analyzed, fabricated, and tested. Three pieces of magnetostrictive materials 2826MB are attached to the mechanical structure at predesigned locations to detect moment, axial force, and torque, respectively. An analytical model was developed to derive the relationship between the input force and the output voltage. The modular design was verified experimentally, and the newly extended torque module can work properly. The sensor&#x2019;s decoupling and stability experiments were conducted. The maximum decoupling error was 3.33&#x0025;, and the maximum stability error was 2.91&#x0025;. The above experiments have verified the rationality and correctness of the innovative modular design of this sensor. It provides new inspirations and possibilities for sensor design.

An In Situ Self‐Assembly Dual Conductive Shell Nanofiber Strain Sensor with Superior Sensitivity and Antibacterial Property

AbstractAt the moment, flexible, stretchable, and wearable strain sensors have extensive application prospect in medical healthcare for their abilities to instantly and accurately monitor human health and body movements, particularly suitable for patients with joint injury and movement disorder, which have attracted more and more attention. Hence, a multifunctional conductive nanofiber composite (M‐CNC) strain sensor with reliable antibacterial property is put forward. The thermoplastic polyurethane (TPU) nanofiber is served as the substrate, decorated by acid‐modified carbon nanotubes (ACNTs) and in situ self‐assembled silver nanoflowers (AgNFs), entitling the M‐CNC with double‐shell conductive networks. The M‐CNC (TPU/ACNT/AgNF) has a stable conductivity, which is up to 7.5 × 105 S m−1. Further, the double‐shell conductive networks have greatly enhanced the sensing performance of the M‐CNC strain sensor, possessing a useful gauge factor of 55 352, during the strain of 42% to 100%. Additionally, the outer AgNF shell structure is stable even after the cyclic test for 1000 times under the strain of 50%. The AgNF also endows the M‐CNC with great antibacterial property, indicating brilliant growth inhibition effects on Gram‐negative Pseudomonas aeruginosa and Gram‐positive Staphylococcus aureus.

A Moment and Axial Force Sensor Using a Self-Decoupled, Passive and Wireless Method

A moment and axial force sensor using a self-decoupled, passive and wireless method was proposed, designed, analyzed, fabricated and tested. A specially designed mechanical structure based on a joint ball bearing was proposed to realize the intrinsic self-decoupling operation. Two pieces of Metglas 2826MB magnetostrictive material were attached at predesignated positions on a mechanical structure to detect the moment and axial force separately. The magnetostrictive material enabled the passive and wireless detection based on the Villari effect. An analysis model was established to derive the relationship between the input forces and output voltages. Experiments were carried out to verify the self-decoupling performance, dynamic performance, drift performance and hysteresis performance of the sensor. We proved that the decoupling error of the sensor was less than 2.4%, the dynamic error of the sensor was less than 6.15%, and the sensor could fulfill passive and wireless detection. Compared with traditional multidimensional sensors, our sensor showed advantages of intrinsic self-decoupling, passive and wireless, and dynamic detection. These advantages enable the sensor to have potential applications in cutting tool force detection, sealed gearboxes, etc.

The interaction between the transient cavitating flow and hydrodynamic performance around a pitching hydrofoil

The interaction between the unsteady cavitating flow and hydrodynamic performance around a pitching Clark-Y hydrofoil is investigated experimentally and numerically. The experiments were conducted in the looped cavitation tunnel, and the cavitation patterns are documented by two high-speed digital cameras, and the moment of hydrofoil is measured by the moment sensor. The pitching hydrofoil is controlled from α+ = 10° to α+ = 15° firstly, and goes back to α− = 5° from α+ = 15°, then goes back to α+ = 10° from α− = 5° at Re = 4.4∗105. The upstream velocity U∞ and the cavitation number σ is fixed at 6.3 m/s and 1.38, respectively. And the pitching rate is α˙=40∘/s,α˙∗=0.086. The numerical investigations were performed by solving the incompressible UNRANS equations via the commercial code CFX using the Merkle cavitation model, the coupled k-ω SST turbulence model and γ-Reθ transition model. The predicted cavity patterns and moment coefficients agree well with the experimental results. The results showed there are two distinct cavitation patterns (Multi-scale cloud cavitation and Traveling sheet cavitation). For the Multi-scale cloud cavitation phase (α+ = 10°-α- = 10°), the re-entrant flow is the main factor on the stability of cavitating flow structures, which is responsible for different shedding patterns. According to the breaking position and re-entrant flow thickness, this stage is divided into three different patterns of the cavity development and shedding. For the Traveling sheet cavitation phase (α− = 10°-α+ = 10°), the shedding of cavity mainly results from the interaction of the re-entrant flow and the fluctuation of the gas liquid interface, thus leading to the irregular breaking points. The cavitating flow structure of different phases were further investigated using the LESs, which will be help to identify the dynamic behavior of flow structures effectively.

Design and Experiment of a Cardan-Type Self-Decoupled and Self-Powered Bending Moment and Torque Sensor

The conventional force sensors suffer from dimension coupling and energy problems. In this article, a cardan-type self-decoupled and self-powered bending moment and torque sensor were proposed, analyzed, fabricated, and tested. The sensor was mainly composed of a bending moment deforming ring, two torque deforming sheets, and a cardan. The bending moment deforming ring withstood the bending force applied on the sensor individually. The torque deforming sheets bore the torque alone. The separation of the bending moment and torque was realized by the cardan. After that, the coupled bending moment and torque acting on the sensor were decoupled and measured, respectively. Two pieces of magnetostrictive ribbons were bonded on the bending moment deforming ring and torque deforming sheets in order to realize passive and wireless detection. A theoretical analysis of the sensor was carried out. The sensor was fabricated and the experiments were conducted. The experimental results showed that the coupling force separation accuracy of the sensor was over 98%. The sensor could work without an internal power supply for an unlimited time. The sensor shows the merits of self-decoupling, working passively, and wirelessly. The sensor can be potentially used to detect the coupled force on a cutting tool of a machining center.

Decoupled Six-Axis Force-Moment Sensor with a Novel Strain Gauge Arrangement and Error Reduction Techniques.

In this study, a novel strain gauge arrangement and error reduction techniques were proposed to minimize crosstalk reading and simultaneously increase sensitivity on a decoupled six-axis force–moment (F/M) sensor. The calibration process that comprises the least squares method and error reduction techniques was implemented to obtain a robust decoupling matrix. A decoupling matrix is very crucial for minimizing error and crosstalk. A novel strain gauge arrangement that comprised double parallel strain gauges in the decoupled six-axis force–moment sensor was implemented to obtain high sensitivity. The experimental results revealed that the maximum calibration error, F/M sensor measurement error, and crosstalk readings were reduced to 3.91%, 1.78%, and 4.78%, respectively.

마이크로프로세서 제어형 하지의지용 족관절 모멘트 센서의 구조 최적화

마이크로프로세서 제어형 하지의지는 다양한 센서로부터 정보를 획득하여 사용자의 자세, 보행 상태, 동작의도 등을 판별하고 이에 따라 의지를 제어한다. 이러한 센서들 가운데 우리가 하지의지용으로 개발한 족관절 모멘트 센서는 체중이 전달되는 프레임의 변형량을 측정한다. 개발된 기존 센서는 기계적 내구성 시험과정에서 결함이 발견되었으며 입각기 초반의 발뒤꿈치 접지기에서 측정된 값이 입각기 초기 판별에 사용하기 어려운 상황이었다. 본 연구에서는 이러한 문제들을 해결하기 위하여, 보행 시 센서 프레임에 인가되는 하중을 구현한 유한요소해석 모델을 개발하고 각 조건에 따른 응력 및 변형 특성을 분석하였다. 분석결과에 따른 최적화된 프레임 구조 설계안을 도출하였으며, 이에 따라 족관절 모멘트 센서를 제작하고 기계적 실험 및 절단자 보행실험을 통하여 개선방법을 검증하고 성능을 평가하였다. 개선된 센서의 특성을 평가한 결과, 구조적 안전성은 향상되었으며, 입각기 초반 상태 인식률도 개선되었다.

Experimental studies of the air flow power action on the elements of protective mats

The results of experimental studies to determine the coefficients of aerodynamic resistance in the flow of flexible protective concrete mats located on a horizontal plane are presented. The characteristics of the impact of the power flow on the system of flexible protective mats of various modifications in the aerodynamic laboratory of Moscow State University of Civil Engineering are specified. The experiment was carried out on a subsonic wind tunnel with an open loop using a rigid six-axis force and moment sensor. According to the results of the experiment, it was concluded that the resistance coefficient for the modification of mats with rounding of the upper part of the elements decreases. It has a positive effect on the performance characteristics of this model and increases the lifespan of a structure protected by this modification of coatings.

Torque and bending moment acting on a flexible shaft agitated by disk turbines in a gas–liquid stirred vessel

Abstract The torque and bending moment acting on a flexible overhung shaft in a gas–liquid stirred vessel agitated by a Rushton turbine and three different curved-blade disk turbines (half circular blades disk turbine, half elliptical blades disk turbine, and parabolic blades disk turbine) were experimentally measured by a customized moment sensor. The results show that the amplitude distribution of torque can be fitted by a symmetric bimodal distribution for disk turbines, and generally the distribution is more dispersive as the blade curvature or the gas flow rate increases. The amplitude distribution of shaft bending moment can be fitted by an asymmetric Weibull distribution for disk turbines. The relative shaft bending moment manifests a “rising-falling-rising” trend over the gas flow number, which is a corporate contribution of the unstable gas–liquid flow around the impeller, the gas cavities behind the blades, and the direct impact of gas on the impeller. And the “falling” stage is greater and lasts wider over the gas flow number for Rushton turbine than for the curved-blade disk turbines.

Six-Axis Column-Type Force and Moment Sensor for Robotic Applications

A flexible cylindrical beam is used to design a six-axis column-type force and moment sensor for robotic applications, where accurate small force and moment measurements are required. One of the ends of the beam is fixed, and the other remains free. A rigid cover with a mushroom shape is placed at the free end. This cover is the contact surface between the sensor and the object being touched, and it transmits the contact forces and moments to the flexible beam. The 12 miniature strain gauges are strategically placed on the surface of the beam to measure the contact forces and moments by using a simple model based on the classical theory of elasticity. The calibration method of the sensor is performed by using the least-square fitting method, and the experimental results demonstrate that maximum and mean relative errors are below 9% and 3%, respectively, of fullscale in all measured variables.

Design of a calibration setup for the dynamic analysis of multi-component force and moment sensors

For the dynamic calibration of multi-component force and moment sensors, different requirements need to be considered. We describe the mechanical design process for a calibration setup of such sensors with special focus on the generation of uniaxial force and moment components in different axes, with minimized secondary loads. The design is analysed using FEM simulations and experiments.

A calibration rig for multi-component internal strain gauge balance using the new design-of-experiment (DOE) approach.

In a closed water-tunnel circuit, the multi-component strain gauge force and moment sensor (also known as balance) are generally used to measure hydrodynamic forces and moments acting on scaled models. These balances are periodically calibrated by static loading. Their performance and accuracy depend significantly on the rig and the method of calibration. In this research, a new calibration rig was designed and constructed to calibrate multi-component internal strain gauge balances. The calibration rig has six degrees of freedom and six different component-loading structures that can be applied separately and synchronously. The system was designed based on the applicability of formal experimental design techniques, using gravity for balance loading and balance positioning and alignment relative to gravity. To evaluate the calibration rig, a six-component internal balance developed by Iran University of Science and Technology was calibrated using response surface methodology. According to the results, calibration rig met all design criteria. This rig provides the means by which various methods of formal experimental design techniques can be implemented. The simplicity of the rig saves time and money in the design of experiments and in balance calibration while simultaneously increasing the accuracy of these activities.