Six-component Force Sensor Research Articles

Research on Decoupling Model of Six-Component Force Sensor Based on Artificial Neural Network and Polynomial Regression.

A two-stage decoupling model based on an artificial neural network with polynomial regression is proposed for the six-component force sensor load decoupling problem in the case of multidimensional mixed loading. The six-dimensional load categorization stage model constructed in the first stage combines 63 load category label sets with a deep BP neural network. The six-dimensional load regression stage model was constructed by combining polynomial regression with a BP neural network in the second stage. Meanwhile, the six-component force sensor with a fiber Bragg grating (FBG) sensor as the sensitive element was designed, and the elastomer simulation and calibration experimental dataset was established to realize the validation of the two-stage decoupling model. The results based on the simulation data show that the accuracy of the classification stage is 93.65%. The MAPE for the force channel in the regression stage is 6.29%, and 3.24% for the moment channel. The results based on experimental data show that the accuracy of the classification stage is 87.80%. The MAPE for the force channel in the regression phase is 5.63%, and 4.82% for the moment channel.

Design and Experiment of Anti-Blocking Components for Shallow Stubble Clearing Based on Soil Bin Test

In response to the problems of excessive wheat stubble blocking the opener during corn seeding in wheat–corn double cropping areas, an active-strip stubble removal method was proposed under the premise of conservation tillage. Firstly, the effects of two conventional rotary blade structures (inward and outward) on the stubble-cleaning effect and power consumption were studied under five rotary speeds (400, 500, 600, 700, 800 rpm). The results show that when the rotary speed was 400–600 rpm, the outward structure of the rotary blade was more suitable for stubble cleaning. Then, a torque sensor and a six-component force sensor were applied to the soil bin test platform to measure the relative data of four oblique angles (0°, 15°, 22.5°, 30°) on the stubble-cleaning effect, seedbed parameters, and power consumption at three rotary speeds (400, 500, 600 rpm). The results show that the straw residue on the seedbed was effectively reduced when increasing the oblique angle and rotary speed. Moreover, the quality parameters of the seedbed were improved and the power consumption was reduced when reducing the oblique angle and rotary speed. When the rotary speed was 400–500 rpm, the difference between the vertical resistance and lateral resistance was relatively small, while the difference between the horizontal resistance was large.

Optimal design of sensor structure based on virtual calibration test

The design of wheel six-component force sensor includes elastic body, strain gauges distribution scheme, signal acquisition and processing and so on. In this paper, the virtual calibration test is used to optimize the structure of the sensor elastic body. According to the structure and principle of the self-developed six component force sensor calibration test-bed, a set of calibration device is designed for the sensor. The stress distribution and strain output of the elastic body are obtained by finite element method. The optimization of elastic body is carried out from the requirements of material strength and coupling rate of output signal. Finally, the sensor elastic body structure which meets the strength requirements and has low coupling rate is obtained.

A heavy load tire six-component force sensor

This paper presents research on design and calibration of a heavy load tire six-component force (including three forces and three moments) sensor. Differ from common tire six-component force sensor, it is designed mainly for truck tire and aircraft tire test. With a four-column structure in its elastic body, size thinning in the middle of every column is designed to get a higher sensitivity in Fy channel. Before fabricating, the ‘virtual calibration’ is carried out, which proves that the design scheme of strain gauge position and elastic body matches well with each other. For there is low crosstalk between every two output channels. The calibration experiment results are not entirely the same as that in ‘virtual calibration’, for factors such as material heat treatment, machining accuracy and the quality of pasting strain gauges increase crosstalks. With decoupling calculation, a high-accuracy heavy load tire six-component force sensor is still obtained.

Study of the Difference between Single and Multi-component Calibration Results of Tire Six-component Force Sensor

The paper studies the difference between single and multi-component calibration results of tire six-component force sensor. In accordance with the measuring principle of strain gauge, the different formulas of single calibration and multi-component calibration for one strain gauge are deduced. Taking the resistance strain tire six-component force sensor with four column structure as an example, some certain channel output shows a larger error between single and multi-component calibration results, which is the integrated result of structure and measuring bridge. Because of the difference between the two results, single calibration is not better than multi-component calibration when calibrating a sensor working under multi-component force conditions. The simulation experiments of virtual single and multi-component calibrations are conducted based on Hypermesh and Abaqus. Thus, the above conclusions are confirmed by simulation results. In accordance with the verification above, a more reasonable method for tire six-component force sensor calibration is proposed in this paper.

Experimental study of a ducted contra-rotating lift fan for vertical/short takeoff and landing unmanned aerial vehicle application

This study explores the aerodynamic characteristics of a ducted contra-rotating lift fan for vertical/short takeoff and landing application by means of force, pressure, and flow field measurements. The effect of rotating frequency and contra-locomotion on the force generation was examined using a miniature six-component force sensor. Additionally, for the sake of considering the ground effect, the flow field at the exit was investigated using high-response pressure measurement. Results revealed that the lift shows a quadratic generation trend on increasing the r/min where the inherent unsteady flow contradicts the conventional quasi-steady model of propeller. The contra-rotating mechanism can significantly augment the lift while still being lower than double single rotors. The unsteadiness of the contra-rotating rotors is quite obvious where two high-pressure regions are revealed and rotate. When the lift fan approaches the ground, the lift will be augmented significantly due to the surplus of the wake jet.

A 3-D printed redundant six-component force sensor with eight parallel limbs

In this paper, the design, manufacture and calibration test of a 3-D printed parallel six-component force sensor are presented. Aiming at improving the measuring performances and downsizing the outline of six-component force sensor, a novel redundant parallel six-component force sensor with spoke structure combining parallel mechanisms with flexible mechanisms is proposed. The mathematical model of the proposed sensor is established by screw theory which reveals the force mapping relationship. Considering the structure particularity, three-dimensional printing technology is innovatively applied to manufacture six-component force sensor prototype and main details regarding manufacture are described. Calibration tests for the sensor prototype are also carried out. Based on the data recorded in experiments, the calibration matrix is obtained and its performances such as non-linearity, repeatability and hysteresis are analyzed, which show good results in six-component force measurement.

Experimental Investigation of Aerodynamics of Flapping-Wing Micro-Air-Vehicle by Force and Flow-Field Measurements

This study explores the aerodynamic characteristics of a flapping-wing micro aerial vehicle (MAV) in hovering configuration by means of force and flowfield measurements. The effects of flapping frequency and wing geometry on force generation were examined using a miniature six-component force sensor. Additional high-speed imaging allowed identification of the notable different deformation characteristics of the flexible wings under vacuum condition in comparison to their behavior in air, illustrating the relevance of aeroelastic effects. Flow visualization around the flapping wing by means of planar particle image velocimetry (PIV) measurements revealed the formation, development, and shedding of the vortical structures by the wings during flapping motion, with particular emphasis on the clap-and-fling phase. Further stereoscopic PIV measurements performed in the wake showed a momentum surplus wake induced by the clap-and-fling, indicative of thrust generation. The vortical structures in the wake formed during instroke and outstroke were characterized using a three-dimensional wake reconstruction from the planar measurements.

Fault-tolerant parallel six-component force sensor

During some key force measuring tasks in the harsh environment such as aerospace, national defense, deep-sea exploration, higher working reliability is required. The design concept of fault-tolerance is proposed in the design of parallel six-component force sensor. Two kinds of fault-tolerant parallel structure force sensor without pre-stressing platform and two kinds of fault-tolerant and fully pre-stressed parallel structure force sensor using modified spherical pairs, together with another three kinds of wheel-spoke fault-tolerant force sensor are proposed. Compared with traditional Stewart platform-based sensor, the structural characteristics of the sensors are analyzed. The complete mathematic models including the models before and after signal fault are established by using theory of screw and the relations between stiffness and force distribution. The unified mathematic model is suitable for all the fault-tolerant six-component force sensor with different structures proposed in this paper. Calibration study of a sensor prototype without fault and with signal fault is carried out and non-linear errors are analyzed. The research of the paper provides not only theoretical basis and practical significance for the study on high reliable six-component force sensor, but also a new applied orientation for the redundant parallel mechanism.

Design of Six-Component Force Sensor Used in Suspension KC Testrig

A six-component force sensor used in suspension K&C testrig is designed in this paper. Such suspension K & C testrig six-component force sensor can realize six-component force from the principle, avoiding the complex software decoupling. The direct output of six-component force sensor are also taken into account in practice ‘partial pressure’ problem, so it has more extensive practical application significance.

Research on Axis Piezoelectric Six-Component Force/Moment Sensor Clamp Device

The six-component force measurement and real-time force feedback is not only the basis of multi-equipment coordination of operational control and the force comply with the control, but also to develop the technical basis of the overloaded operators, equipment and other heavy equipment. This article designed a fastening device based on the swelling principle of surface friction, for the six-component force sensor with parallel axis rigid connection. Analysis the six-component force sensor measurement principle, study the blessing device dynamometer performance of six-component force sensor. Use the finite element software for modeling and simulation analysis of the structure. Design of the loading experiments, the experiments show that the fastening technology based on the principle of swelling of the surface friction, to solve the six-component force sensor axis fixed and force transmission, interference of swelling structure to the sensor calibration is relatively small, both achieve effective clamping, but also improves the transfer efficiency of the power flow. With good positioning, highly repetitive assembly and disassembly, convenient adjusting device, etc.

Measurement Theory and Experimental Study of Fault-Tolerant Fully Pre-Stressed Parallel Six-Component Force Sensor

To meet the high reliability requirement under complicated environment and overcome the disadvantages of parallel structure six-component force sensor with traditional spherical pairs, the design concepts of fault-tolerance and fully prestressing are proposed to the design of parallel six-component force sensor. A kind of fault-tolerant and fully prestressed parallel structure force sensor using modified spherical pairs is proposed. The structural characteristics of the sensors are analyzed in comparison with traditional Stewart platform-based sensor. The complete mathematic model including the models with and without signal fault is established using screw theory and considering the relations of stiffness and force distribution. The mathematical expression to obtain the lower bound of prestressed force is determined. The static calibration experimental study of a sensor prototype is carried out, and the experimental results prove the superiority of the structure and the correctness of theoretical analysis. Besides, a fault diagnosis method is proposed and verified with a tracking task, which provides a basis for the applied research of the fault-tolerant sensor.

Structural Optimization Design of Parallel Piezoelectric Six-Component Force Sensor

This paper describes structural optimization design of parallel piezoelectric six-component force sensor. Structure, measuring principle, and load sharing principle are introduced. The influences on load sharing effect of each component of sensor’s structure are researched. Main parameters to influence load sharing effect are obtained, and analyzed by finite element method (FEM). It is clear that the analysis results of FEM are well correspond with the theoretical analysis results. Experiment is designed to verify analysis results. The trend is in consistent with FEM analysis.The paper provides reference basis for design of parallel piezoelectric six-component force sensor.

Age effects on rotational hand action

We investigated age-related differences in finger coordination during rotational hand actions. Two hypotheses based on earlier studies were tested: higher safety margins and lower synergy indices were expected in the elderly. Young and elderly subjects held a handle instrumented with five six-component force sensors and performed discrete accurate pronation and supination movements. The weight of the system was counterbalanced with another load. Indices of synergies stabilizing salient performance variables, such as total normal force, total tangential force, moments produced by these forces, and total moment of force were computed at two levels of a hypothetical control hierarchy, at the virtual finger-thumb level and at the individual finger level. At each level, synergy indices reflected the normalized difference between the sum of the variances of elemental variables and variance of their combined output, both computed at comparable phases over repetitive trials. The elderly group performed the task slower and showed lower safety margins for the thumb during the rotation phase. Overall, the synergy indices were not lower in the elderly group. In several cases, these indices were significantly higher in the elderly than in the younger participants. Hence, both main hypotheses have been falsified. We interpret the unexpectedly low safety margins in the elderly as resulting from several factors such as increased force variability, impaired feed-forward control, and the fact that there was no danger of dropping the object. Our results suggest that in some natural tasks, such as the one used in this study, healthy elderly persons show no impairment, as compared to younger persons, in their ability to organize digits into synergies stabilizing salient performance variables.

Bionic Integration of the Spherical Parallel Shoulder Joint with the Six-Component Force Sensor

Based on the bionics principle, this paper proposed the idea of bionic design of the spherical parallel shoulder joint integrated with the six-component force sensor. The static analysis of the 3-RRS mechanism, which can be taken as a prototype mechanism of shoulder joint of humanoid robot, was carried out. And the relationship figures between the forces and torques acted on each component and the pose of the mechanism were obtained. The measurement of the external load and driving torques, which was employed to judge operability of arm to the target object under arbitrary pose, was realized by introducing resistance measurement method in the mechanism. The bionic integration of the shoulder joint with six-component force sensor made arm has some functions such as to avoid overload and singular area voluntarily, and realize self-protection. The contents of this paper lay a foundation of compliant control of humanoid robot arm and have important significance and value in engineering.

Design of a compact six-component force and moment sensor for aerodynamic testing

The measurement of steady and fluctuating forces acting on a body in a flow is one of the main tasks in wind-tunnel experiments. Usually, a multi-component strain gauge force and moment sensor (also known as balance) is used to generate signals which are processed by means of an adequate instrumentation. To design a wind-tunnel balance, the specifications of the load ranges and the available space (for the placement of the balance inside or outside the model) are required. The main challenge is to conceive the elastic element of the sensor as a monolithic part with a relative simple geometry and to identify the adequate placement of strain gauges to maximize the measuring sensitivities and to diminish the inter-influence of the components. This paper describes the design of a six-component force/moment sensor which is compact, has high measuring sensitivities, and can be used either as internal or as external balance in the aerodynamic testing.

Task-oriented Design of the Parallel Six-component Force Sensor

Currently,the performance of the parallel six-component force sensor is mostly evaluated by the isotropy.However,in practice,the sensor is used to perform a certain task which is not necessarily to be isotropic.Therefore,task-oriented structural design of a sensor has important significance to the practical application of the six-component force sensor.The static mathematic model is built by using the screw theory.Based on the task ellipsoid which is proposed from the grasping planning,the task model,which is divided into the force ellipsoid and the torque ellipsoid,is built.The relationship between the sensor and the task is studied.Then the analytical expression is deduced.The mathematic description of task-oriented performance evaluation is proposed.The six-component force sensor based on the Stewart platform which is used to perform the task of the inserted pin and the exploration is studied respectively,and the relationship between the task model and the structural parameters of the sensor is obtained.The research results are useful for the practical application of the six-component force sensor.

Development and Calibration of a Hyperstatic Six-component Force/Torque Sensor

The six-component force/torque sensor has become one kind of the most important sensors with the ability of measuring all the external forces and torques. A novel hyperstatic six-component force/torque sensor based on the Stewart platform structure,which can be used for the force measurement of the robot wrist,is proposed,and its structural optimal design,finite element analysis and calibration experimentation is presented. The characteristic of the sensor structure is analyzed in comparison with the traditional Stewart platform-based sensor. The mathematical expression of the sensor's force mapping matrix is introduced. The condition number and generalized amplifying coefficient defined by singular values of force Jacobian matrix are used to evaluate the performances of isotropy and sensitivity of the sensor respectively. The optimal design of the sensor structure is performed with the objective of achieving high measurement sensitivity and good isotropy. The sensor prototype is fabricated,and the static and dynamic characteristics of the sensor are analyzed with finite element analysis software package ANSYS. The calibration device is manufactured,and the data acquisition and processing system is developed. The theoretical and experimental study of the static calibration of the sensor prototype is carried out. The results of simulation analysis and calibration experimentation prove the feasibility of the hyperstatic sensor structure,and the contents of this paper possess theoretical significance and engineering value for the further research and practical application of the six-component force sensor.

Performance analysis and comprehensive index optimization of a new configuration of Stewart six-component force sensor

This paper proposes a new configuration of six-component force/torque sensor based on Stewart platform, and discusses the performance analysis and comprehensive index optimization of the six-component force sensor. Based on the classical Stewart platform-based force sensor, a modified sensor structure is proposed, and their statics mathematical models are built by using the screw theory. The condition number and generalized amplifying coefficient defined by singular values of force Jacobian matrix are used to evaluate the performance of sensor, such as isotropy, sensitivity, stiffness, etc. The effect of spherical joint frictional moment on the sensor is established by using the related force mapping matrix. With the combination of the defined performance indices, the comprehensive index optimization of the structural parameters of the modified Stewart six-component force sensor is achieved by using the indices atlases and genetic algorithm. The research results of the paper are useful for the design and further research of the six-component force sensor.

Joystick control with reflection of the motion execution

A joystick with reflection of the motion execution is described. The joystick maintains specification of the motion along six degrees of freedom from a six-component force sensor and reflection of the motion execution with the help of a mobile platform, which is touched by the hand. The operator perceives the data on motion execution through the hand skin, becoming aware of the value of the deviation of the platform from the initial position. The distinction of the joystick design from the existing devices of six-component control with force reflection consists in the fact that the devices for specification and reflection of the motion are not kinematically connected. Because of this, the platform motion practically does not affect the operation of the task part of the joystick, which allows one to repeat even small deviations in a given motion.