Calibration Of Force Sensor Research Articles

Research on Calibration Method of Six Dimensional Force Sensor at the End of Robot

A six-axis force sensor calibration method for industrial robots is proposed to meet the demand for precise force measurement of end effectors in industrial robots. Firstly, establish a sensor data relationship calculation model, and based on this, focus on considering the interference caused by sensor "zero drift"; Then, the least squares method is used to determine the inclination angle between the robot's end effector and the installation of the six-axis force sensor, the gravity of the end effector, and the coordinate parameters of the center of gravity. Finally, a CR5 robotic arm experimental platform was built to verify the feasibility of the algorithm. The experiment showed that the calibrated sensor maintained a stable force value of 0N without external force, verifying the accuracy of the calibration algorithm.

Calibration of force sensor

The paper deals with the issue of calibration of an analogue force sensor with a voltage output. For measurement, the force sensor uses a deformation member with a tensometric bridge and a measuring amplifier. This measuring chain must be used for force measurement, but the measurement uncertainty of this measuring chain is not known. Force sensors are planned for use in intelligent traumatological external fixation systems.

Open-source tribometer with high repeatability: Development and performance assessment

A novel conception of Arduino-based open-source tribo-testing system with high repeatability, low-cost, and easy-redeveloped initiative capabilities was demonstrated. The mechanical platform design, electrical circuit design, control and data acquisition, software interface, and force sensor calibration are described and discussed in detail. A complete set of the open-source tribometer development plan is revealed. Representative tribological tests were performed to evaluate the performance and generality of the developed open-source tribometer. Results of the tests show that the intraclass correlation coefficients (ICC) of diamond-like carbon (DLC) film, Polytetrafluoroethylene (PTFE), high-entropy alloys (HEAs) film, and silicon (Si) wafer are 0.99941, 0.99932, 0.99918, and 0.994847, respectively, which demonstrates high repeatability and reliability in the three parallel tests using the developed open-source tribometer. Beyond the fundamental interest in this pin-on-disc type tribo-testing system, several open-source options for different types of friction contact and environments are also explored to show that the customized Arduino-based open-source tribometer can lead to further insight into the tribological phenomena based on the real-life service condition, thus being suitable not only for tribological evaluation but also for elucidating underlying mechanisms.

A novel one-dimensional force sensor calibration method to improve the contact force solution accuracy for legged robot

• This method can be carried out on LHDS without disassembling the force sensor. • This method can avoid the irregular variation of calibration coefficient. • This method can simply compensate for the influence of dynamics. Abstract In this paper, aiming at the phenomenon that the calibration coefficient deviation of the one-dimensional force sensor will lead to the deviation in measuring force, a novel method is proposed to recalibrate the one-dimensional force sensors of each joint directly on the leg hydraulic driving system (LHDS) of legged robot. This method has two main contributions. One is that it not only can be carried out directly on LHDS without disassembling the force sensor but also can avoid the irregular variation of calibration coefficient caused by the installation preloading force, friction, mechanical clearance, and other factors. The other is that the method can simply compensate for the influence of dynamics in the calibration process and avoid the complicated mathematical calculation. Under eight working conditions, the experimental results show that the proposed calibration method can decrease the foot end contact force deviation rate more than 20% in the whole cycle. The novel calibration method proposed in this paper can be extended to any leg structure equipped with the same kind of one-dimensional force sensor. It has practical value in engineering.

Model-Based Research on Deviation in Dynamic Force Sensor Calibration Process

For dynamic force calibration, it is essential to accurately determine the force applied to a force sensor. The dynamic force calibration device at Changcheng Institute of Metrology and Measurement uses a laser interferometer to measure the impact force of a falling mass. However, due to the base vibration and inertia forces, the force calculated through the hammer acceleration measured by the laser interferometer and the force measured by the sensor are different. This difference can be observed in calibration experiments by comparing the signals obtained by the laser interferometer and the calibrated force sensor. To correct the deviation and explain this difference, three models are proposed and analyzed in this study. The three models were designed using different degrees of freedom according to different dynamical hypotheses. A lnear fitting approach was used to identify the model parameters. To verify the model and parameters, a simulation model was obtained, and it was calculated using SIMULINK. Subsequently, the simulation model was compared to the experimental data. The results in this study show that the three-degree-of-freedom model can accurately reflect the dynamic behavior of the calibration device. Therefore, the measured reference force can be corrected to obtain the force measured using the force sensor through a quantitative model of this kind, and this correction can improve the dynamic force sensor calibration process.

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.

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.

УСТРОЙСТВА ДЛЯ ЭКСПЕРИМЕНТАЛЬНОГО ОПРЕДЕЛЕНИЯ НАГРУЖЕННОСТИ РАБОЧИХ ОРГАНОВ МТА МЕТОДОМ ТЕНЗОМЕТРИРОВАНИЯ

The efficiency of a field fleet unit is largely determined by the characteristics of the traction resistance of an agricultural machine, which are of a probabilistic nature and require experimental determination. The disadvantage of the known devices that provide measurements during the volumetric dynamometry of the working bodies of tillage machines and implements is the complexity of the design and a significant measurement error. To increase the accuracy of measurements of the dynamic loading of the working bodies of tillage machines, it is necessary to improve the measuring instruments that ensure the reduction of the error. The experimental determination of the loading of the working bodies requires the use of force sensors acting on the working bodies in different planes. Force transducers are mainly manufactured using strain gages, which are glued directly to parts with various cross-sections. To determine the efforts in the rods of the hydraulic linkage system of agricultural tractors use strain gauge fingers, which are cylinders with strain gages glued to them. It is shown that at equal distances l1 and l2 of the location of the sensors, the resulting signal does not depend on the l0 distance of force application on the axis of the finger. Typically, the calibration of force sensors is carried out on additional devices one by one under conditions as close as possible to real ones. The best calibration results will be when all sensors (strain gauge fingers) are installed in their original places and all sensors are calibrated at once. To do this, the intermediate plate is fixed with the help of tension fingers on the hydraulic tractor levers. Eyebolts are installed on the plate, to which a known force Р is applied three times and readings are taken from each of the strain gauge fingers. By solving the resulting system of equations, for example, using the Gauss method in the MathCad environment, all the calibration coefficients are simultaneously found. Additionally, a device is proposed, the kinematic diagram of which allows the use of a single measuring device, which simplifies the technology of measuring the force on the working body and increases its accuracy.

Neural Network Enhanced Robot Tool Identification and Calibration for Bilateral Teleoperation

In teleoperated surgery, the transmission of force feedback from the remote environment to the surgeon at the local site requires the availability of reliable force information in the system. In general, a force sensor is mounted between the slave end-effector and the tool for measuring the interaction forces generated at the remote sites. Such as the acquired force value includes not only the interaction force but also the tool gravity. This paper presents a neural network (NN) enhanced robot tool identification and calibration for bilateral teleoperation. The goal of this experimental study is to implement and validate two different techniques for tool gravity identification using Curve Fitting (CF) and Artificial Neural Networks (ANNs), separately. After tool identification, calibration of multi-axis force sensor based on Singular Value Decomposition (SVD) approach is introduced for alignment of the forces acquired from the force sensor and acquired from the robot. Finally, a bilateral teleoperation experiment is demonstrated using a serial robot (LWR4+, KUKA, Germany) and a haptic manipulator (SIGMA 7, Force Dimension, Switzerland). Results demonstrated that the calibration of the force sensor after identifying tool gravity component by using ANN shows promising performance than using CF. Additionally, the transparency of the system was demonstrated using the force and position tracking between the master and slave manipulators.

A novel testing system for biomechanical evaluation of the bone or bone fixator

PurposeBiomechanical properties of bones and fixators are important. The aim of this study was to develop a new device to simulate the real mechanical environment and to evaluate biomechanical properties of the bone with a fixation device, including the static force and the fatigue characters.Design/methodology/approachIn this paper, the device is mainly composed of three parts: pull-pressure transmission system, bending force applying system and torsion applying system, which can successfully simulate the pre-introduced pull-pressure force, bending force and torsion force, respectively. To prove the feasibility of the design, theoretical analysis is used. It is concluded from the simulated result that this scheme of design can successfully satisfy the request of the evaluation.FindingsFinally, on the basis of the force sensor calibration, the static force experiment and fatigue experiment are carried out using the tibia of the sheep as the specimen. It is concluded from the result that the relationship between the micro displacement and the applied axial force is nearly linear. Under the condition of 1 Hz in frequency, 500 N in loading force and 18,000 reciprocating cycles, the bone fixator can still be in good condition, which proves the feasibility of the design.Originality/valueBiomechanical properties of bones and fixators are studied by researchers. However, few simulate a real force environment and combine forces in different directions. So a novel system is designed and fabricated to evaluate the biomechanical properties of the bones and fixators. Results of the experiments show that this new system is reliable and stable, which can support the biomechanical study and clinical treatment.

Prospective Evaluation of Innovative Force Assessing Firmware in Simulation to Improve the Technical Competence of Surgical Trainees.

Suturing is an integral part of all surgeries. In minimal access surgery, the force exerted is based only on visual perception (tautness of the thread and degree of tissue deformation). An unbalanced suture force can cause tissue rupture or cut-through resulting in avoidable morbidity and mortality. There is a need to find ways of improving surgical dexterity and finesse without adversely affecting patient outcomes. We aimed to calculate the knot-tying force in minimal access pancreatic surgery (MAPS) performed by experienced surgeons (ES) and use this information to develop a surgical suturing model to train the surgical trainees. We have developed a firmware for force sensor calibration and post-data analysis, using which we aimed to compare the differences in forces applied by a trainee as compared to ES. Our technology showed that, as compared to the ES, the trainee's (TS) knot was unbalanced with significant differences in force applied per knot for each of the knots (P < 0.01). The shape of the Force curve for each suture was also different for the TS as compared to the ES. After using the training tool, the forces applied by the TS and the Force curve for the whole suture were similar to those of the ES. Our firmware promises to be an excellent training tool for organ anastomosis. Considering the complexity and likely complications of MAPS, it is a sine qua non that the surgeon be highly experienced and skilled. Surgical simulation is attractive because it avoids the use of patients for skills practice and provides relevant technical training for trainees before they can safely operate on humans.

The Design of a Multi-Functional Force Loading Device

As a mechanical component, sensor can detect spatial information. Sensor technology has been widely used in national defense, aerospace, industrial inspection and automated production areas and so on. However, the sensor calibration device cannot meet the demand of the development of the sensor. In this paper, a multi-functional force loading device, which is of good technical performance, reliable operation, wide measurement range and simple measurement method, and a six-dimensional force sensor calibration method are described.

Micro Friction Experimental Study Based on Parallel Cantilever

In this paper, the law of micro-friction in meso-scale is studied, one optical testing method of micro friction based on the structure of parallel cantilever is given and the testing system is designed, the composition of test system, testing method, the design of force sensor, the testing method and the calibration of force sensor are introduced. The force sensor is calibrated and the deformation of sensor is measured by light reflection. Then the micro friction is obtained by analyzing data. The results of experiment show the resolution of specification of micro friction testing is 10μN, which could meet the demands of micro friction testing with short stroke and high resolution and realize the precise test of micro friction, and the same time it has been analysed which load is unstable during testing.

Precision Force Measurement Using the Levitation Mass Method (LMM)

This paper reviewed the present status and the future prospects of a method for precision mass and force measurement based on levitation mass method (LMM). The LMM has been proposed and improved by the author The mass which levitated using a pneumatic linear bearing in LMM is used to producte a inertial force which used as the reference force applied to the objects under test, such as to force sensor calibration, material and structure test. The inertial force is calibrated only from Doppler shift frequency. The stability of laser’s wavelength has improved in the LMM. The futhure work and the method to improve the precision have described.

A Systematic Design Procedure to Minimize a Performance Index for Robot Force Sensors

This paper presents a systematic procedure for the structural design of a robot force sensor. The structural design is important since the force sensor detects forces and moments through the measurement of strains at specific points of the sensor body. The process of the measurement of force and moment is firstly analyzed from the viewpoint of structural behavior and then a performance index of the force sensor is introduced. It is demonstrated that the minimization of this index (the condition number of the strain compliance matrix) yields an optimal design in the sense that the static measurement error is minimized. It is proposed that the finite element be used for the evaluation of this index in the design process to search for the sensor dimensions that yield the minimum index. This way of proceeding eliminates the need of building intermediate prototypes. A systematic procedure for force sensor calibration is also presented. As an example, a force sensor of the Maltese cross bar type is constructed, and analyzed numerically and experimentally. The agreement between both sets of results corroborates the proposed design sequence.