Strain Gauge Force Sensor Research Articles

Force matching: motor effects that are not reported by the actor.

We explored unintentional drifts of finger forces during force production and matching task. Based on earlier studies, we predicted that force matching with the other hand would reduce or stop the force drift in instructed fingers while uninstructed (enslaved) fingers remain unaffected. Twelve young, healthy, right-handed participants performed two types of tasks with both hands (task hand and match hand). The task hand produced constant force at 20% of MVC level with the Index and Ring fingers pressing in parallel on strain gauge force sensors. The Middle finger force wasn't instructed, and its enslaved force was recorded. Visual feedback on the total force by the instructed fingers was either present throughout the trial or only during the first 5s (no-feedback condition). The other hand matched the perceived force level of the task hand starting at either 4, 8, or 15s from the trial initiation. No feedback was ever provided for the match hand force. After the visual feedback was removed, the task hand showed a consistent drift to lower magnitudes of total force. Contrary to our prediction, over all conditions, force matching caused a brief acceleration of force drift in the task hand, which then reached a plateau. There was no effect of matching on drifts in enslaved finger force. We interpret the force drifts within the theory of control with spatial referent coordinates as consequences of drifts in the command (referent coordinate) to the antagonist muscles. This command is not adequately incorporated into force perception.

Research on measurement methods and sensor selection of rocket gas jet impact force

Based on a rocket launcher gas jet impact force measurement method, this paper designed an experiment to study the influence of different types of sensors on the test results. By comparing and analysing the data waveforms and amplitudes measured by the three sensors at different distances, the accuracy of the test results of each sensor is obtained. The test results show that, for the gas jet impact force measurement method introduced in this paper, the choice of the DYLY-107 S-type strain gauge force sensor can more accurately monitor the impact flow field and impact force amplitude.

The Cracking of Al-Mg Alloys Welded by MIG and FSW under Slow Strain Rating.

Al-Mg alloys used in the shipbuilding industry were tested. The most commonly used alloy AW 5083 and alloy AW 5059 with higher strength properties were selected. Both native materials and their joints welded by the traditional MIG arc welding method and the friction stir welding (FSW) method were tested. Both methods are approved by classification societies which allow them to be used in construction by the shipbuilding industry. The research was carried out in two stages. The first study was an "in-situ tensile test in SEM". The surfaces of the deformed specimens' changes were observed in the vacuum chamber of a Philips XL30 scanning electron microscope. During the tests, the force and elongation of the specimen were recorded. In addition, a chemical analysis of selected precipitates was performed by energy dispersive spectrometry (EDS) using the EDAX adapter. Slip lines were observed on the surface of the tested specimens, which are arranged in bands in the native material and in a disordered manner in the joints welded by MIG and FSW methods. Cracking starts mainly through decohesion at the matrix-precipitate interfaces. In the second stage of the research, slow strain rate testing (SSRT) was carried out in accordance with ISO 7539-7:2005. The tests were carried out on a specially designed test stand, where the FT-5307 strain gauge force sensor with a measuring range of 0-16 kN was used to measure the force value. The PSz 20 transducer with a measuring range of 0-20 mm was also used. The test consisted of subjecting the specimen to increasing deformation with the strain rate έ = 1.6 × 10-6 s-1 until destruction. The fracture surfaces of the SSRT specimens were subjected to fractographic analysis using a Philips XL-30 scanning electron microscope. The results of fractographic studies after the SSRT test of the native materials and their joints welded by the MIG and FSW methods indicate that the trans-crystalline cracking mechanism is dominant, characterized by ductile fracture, and cracks are initiated at the interfaces of the precipitates with the matrix. The research results show that the plastic deformation increases and micro-cracks develop and merge into a main crack, which, after reaching the critical dimension, rapidly develops, causing the destruction of the material. The fracture micrographs of the specimens of base metals and their joints welded by FSW and MIG after the SSRT test allow us to conclude that the cracking mechanism was trans-crystalline ductile.

One-shot additive manufacturing of robotic finger with embedded sensing and actuation

A main challenge in the additive manufacturing (AM) field is the possibility to create structures with embedded actuators and sensors: addressing this requirement would lead to a reduction of manual assembly tasks and product cost, pushing AM technologies into a new dimension for the fabrication of assembly-free smart objects. The main novelty of the present paper is the one shot fabrication of a 3D printed soft finger with an embedded shape memory alloy (SMA) actuator and two different 3D printed sensors (strain gauge and capacitive force sensor). 3D printed structures, fabricated with the proposed approach, can be immediately activated after their removal from the build plate, providing real-time feedback because of the embedded sensing units. Three different materials from two nozzles were extruded to fabricate the passive elements and sensing units of the proposed bioinspired robotic finger and a custom-made Cartesian pick and place robot (CPPR) was employed to integrate the SMA spring actuator into the 3D printed robotic finger during the fabrication processes. Another novelty of the present paper is the direct integration of SMA actuators during the 3D printing process. The low melting thermoplastic polycaprolactone (PCL) was extruded: its printing temperature of 70 °C is lower than the SMA austenitic start temperature, preventing the SMA activation during the manufacturing process. Two different sensors based on the piezoresistive principle and capacitive principle were studied, 3D printed and characterized, showing respectively a sensitivity ratio of change in resistance to finger bending angle to be 674.8 frac{Omega }{^circ mathrm{Angle}} and a capacitance to force ratio of 0.53 frac{mathrm{pF}}{mathrm{N}}. The proposed manufacturing approach paves the way for significant advancement of AM technologies in the field of smart structures with embedded actuators to provide real-time feedback, offering several advantages, especially in the soft robotics domain.

Novel Planar Strain Sensor Design for Capturing 3-Dimensional Fingertip Forces from Patients Affected by Hand Paralysis.

Assessment and therapy for individuals who have hand paresis requires force sensing approaches that can measure a wide range of finger forces in multiple dimensions. Here we present a novel strain-gauge force sensor with 3 degrees of freedom (DOF) designed for use in a hand assessment and rehabilitation device. The sensor features a fiberglass printed circuit board substrate to which eight strain gauges are bonded. All circuity for the sensor is routed directly through the board, which is secured to a larger rehabilitative device via an aluminum frame. After design, the sensing package was characterized for weight, capacity, and resolution requirements. Furthermore, a test sensor was calibrated in a three-axis configuration and validated in the larger spherical workspace to understand how accurate and precise the sensor is, while the sensor has slight shortcomings with validation error, it does satisfy the precision, calibration accuracy, and fine sensing requirements in orthogonal loading, and all structural specifications are met. The sensor is therefore a great candidate for sensing technology in rehabilitation devices that assess dexterity in patients with impaired hand function.

Torque measurement for researching the energy characteristics of electric vehicle drives

Purpose. Development of a torque measuring unit as part of a laboratory complex for studying the energy characteristics of electric drives for the purpose of mathematical modeling of the dynamic operating modes of an electric vehicle drive. Research methods. Physical experiment, regression analysis, interpolation. Findings. A torque measuring unit has been developed as part of a laboratory complex for studying the energy characteristics of electric vehicle drives, the design of which allows creating a torque on the shaft of the engine under study using a load and measuring it with a strain gauge force sensor. The laboratory stand together with the developed torque measuring unit corresponds to the required range and measurement accuracy. The experimental data obtained at the test bench make it possible to determine the dependence of the energy consumed by the drive on the mechanical power on the shaft of the engine under study, which makes it possible to analytically describe the drive under study and carry out mathematical modeling in the context of studying the influence of mechanical parameters on the consumed energy in dynamic modes of operation. Originality. A method for measuring torque on the motor shaft for studying the energy characteristics of electric vehicle drives has been developed. This method is based on the contact method of measurement, which uses 2 motors (loading and testing) and strain gauge force sensor and differs from others in the design that creates a moment on the shaft of the test motor.The result of processing the experimental data obtained by this method is the analytical dependence of the energy consumed by the drive on the value of the mechanical power on the shaft, the parameters of which are the angular speed and torque of the engine. The specified energy characteristic of the drive makes it possible, by means of mathematical modeling, to determine the electromechanical parameters of the drive, minimizing its energy consumption in dynamic modes of operation. Practical value. A method for measuring the moment on the motor shaft is proposed, with the help of which the dependence of the energy consumed by the drive on the mechanical power on the motor shaft is determined in an analytical form, which allows by mathematical modeling to find the electromechanical parameters of the system that increase the energy efficiency of the drive of an electric vehicle.

3D-Printed Strain-Gauge Micro Force Sensors

This paper presents the development of 3D-printed micro force sensors with micronewton sensing resolutions. Two representative 3D printing techniques, fused deposition method (FDM) and stereolithography (SLA), are utilized to establish polymeric micro sensor structures with a resolution down to 300 μm. Two types of 3D-printed strain-gauge force sensors have been designed aiming at different force measurement ranges (0-2.5 mN and 0-120 mN) with micronewton force sensing resolutions (4.3 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</sub> N and 56 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</sub> N, respectively). As a proof-of-concept demonstration, the two 3D-printed force sensors are used in custom-made mechanical characterization systems for measuring Young's moduli of polydimethylsiloxane (PDMS) samples at different crosslinking levels. The experimental technique presented here could empower rapid prototyping of high-performance force sensors utilizing consumer-level 3D printers, and will significantly boost the flexible design and customization of force-sensing systems with a variety of design requirements.

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.

Design and Development of a Novel Compliant Gripper With Integrated Position and Grasping/Interaction Force Sensing

This paper proposes a new compliant gripper with integrated position and force sensors dedicated to automated microassembly tasks. The uniqueness of the gripper is that it possesses a large gripping range with a bidirectional drive, and it is capable of detecting grasping force and environmental interaction forces in horizonal and vertical axes, respectively. This is enabled by a mechanism design based on a rotary flexure bearing. Moreover, a compliant mechanism with two-stage stiffness is designed to provide the force sensing with dual sensitivities and measuring ranges to accommodate the grasp of objects with different sizes and weights. Analytical models are derived to predict the grasping range, force sensing sensitivities, and ranges. These models are verified by conducting finite-element analysis simulations. A proof-of-concept prototype gripper is developed for experimental calibration and performance testing. Results reveal that the single set of strain-gauge force sensor is able to detect both grasping and interaction forces in an alternate manner. The dual-sensitivity, dual-range force sensor provides a solution to large-range gripper with finer and coarser force sensing in a small and large ranges, respectively .

Performance evaluation of a strain-gauge force sensor for a haptic robot-assisted catheter operating system

A robotically assisted catheterization system can obviously reduce the radiation exposure to the surgeon and lesson the fatigue caused by standing for long time in protective clothing. However, effective detection and feedback of proximal force signals is essential to the success of a surgery. This paper presents a compact, cost-effective force-sensing device based on strain gauges, for our team developed slave side, to measure the proximal force signals of the input catheter. A significant advantage is that the proposed sensing device can detect the force signals directly without any mechanical transmission, and this can increase the measurement accuracy of force information. In addition, a haptic interface based on MR fluid is designed to provide a realistic sense of operation according to the force signals from the slave side, so as to improve the safety and success of a surgery. Comparing experimental results from an insertion test and a load cell, show that the average error for force measurement is less than 0.01 N. This research provides important insights into the design of compact, ergonomic, robotic catheter manipulators for intraoperative navigation using effective tactile sensing devices.

Contactless flow measurement in liquid metal using electromagnetic time-of-flight method

Measuring flow rates of liquid metal flows is of utmost importance in industrial applications such as metal casting, in order to ensure process efficiency and product quality. A non-contact method for flow rate control is described here. The method is known as time-of-flight Lorentz force velocimetry (LFV) and determines flow rate through measurement of Lorentz force that act on magnet systems that are placed close to the flow. In this method, a vortex generator is used to generate an eddy in the flow, with two magnet systems separated by a known distance placed downstream of the vortex generator. Each of the magnet systems has a force sensor attached to them which detects the passing of the eddy through its magnetic field as a significant perturbation in the force signal. The flow rate is estimated from the time span between the perturbations in the two force signals. In this paper, time-of-flight LFV technique is demonstrated experimentally for the case of liquid metal flow in a closed rectangular duct loop that is driven by an electromagnetic pump. A liquid metal alloy of gallium (Ga), indium (In) and tin (Sn)—GaInSn—is used as the working fluid. In contrast to prior works, for the first time, three-dimensional strain gauge force sensors were used for measuring Lorentz force to investigate the effect of flow disturbances in different directions for flow measurements by the time-of-flight LFV method. A prototype time-of-flight LFV flowmeter is developed, the operation of which in laboratory conditions is characterised by different experiments.

Calculation and optimization of weight measuring sensor in motor-truck scales

The article considers the possibility of using multicriteria optimization methods for the design of elastic elements for force sensors. The calculations and studies on the example of an elastic membrane element for strain gauge force sensor were conducted.

Stochastic modeling of lift and drag dynamics under turbulent wind inflow conditions

AbstractWe present a new approach to model the complex dynamics of aerodynamic forces on an airfoil in turbulent inflow conditions. Our ansatz is based on stochastic differential equations and aims at replacing traditional look‐up table methods used in wind turbine simulation systems by the effective response dynamics of lift and drag forces. The parameters of the model are derived directly from empirical data. Measurements were taken in the closed loop wind tunnel of the University of Oldenburg for an airfoil FX 79‐W‐151A. The turbulent inflow was generated using a fractal square grid as it is possible to generate in this way wind speed fluctuations with similar statistics as observed in nature. Forces were measured using two strain gauge force sensors at two end points of the vertically installed airfoil. The modeling is performed by applying a stochastic approach on the measured data. By estimating the first two Kramers–Moyal coefficients, a first‐order stochastic differential equation called the Langevin equation is obtained. The stochastic model achieved through this approach is extended to account for oscillation effects contained in lift and drag dynamics that probably stem from unsteady aerodynamic effects. The results are optimized by applying a χ2 test on the probability density functions (PDFs) of model and measurements. With the knowledge of the Langevin equation, synthetic time series are generated. Their stationary PDFs as well as conditional PDFs show good agreement with the actual measurements. A comparison of classical averaging and the stochastic approach shows that stochastic analysis achieves additional insight into the local dynamics of lift and drag forces. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Расчет мембранного упругого элемента тензорезисторного датчика силы

Расчет мембранного упругого элемента тензорезисторного датчика силы

The influence of the undercarriage and tire inflation rating on drawbar characteristics of tractors

The aim of the measurement was to verify the drawbar characteristics of chosen tractors with different undercarriages. The tractors were of the same engine power as well as type of gearbox (PowerShift – gears full shifted while loaded). We were dealing with the wheeled tractor John Deere 8320 and crawler tractor John Deere 8320RT. The measurement was implemented in the land register of Vrbovec (Znojmo region) in an area where green peas were grown as the main product and winter wheat as the preceding crop. The measured and the counterproductive tractors were interconnected by the rope containing strain-gauge force sensors. The wheeled tractor was decelerated by the tractor crawler. The tractor crawler was decelerated by two wheeled tractors. The wheeled tractor’s stress-strain properties were also measured applying two pressure rating alternatives. Variant A presented inflation pressure of 160 kPa on the front axle and of 140 kPa on the rear axle. Variant B applied inflation pressure of 120 kPa on the front axle and of 100 kPa on the rear axle. Measured and calculated findings reveal that the tractor crawler achieved higher drawbar power and lower specific tractive consumption and traction slip than the wheeled tractor with both variants of inflation. Comparing the stress-strain characteristics of the wheeled tractor with a different tire inflation illustrates that using variant B, higher drawbar power and lower specific tractive consumption and traction slip were measured.

High accuracy volume flow rate measurement using vortex counting

A prototype device for measuring the volumetric flow-rate by counting vortices has been designed and realized. It consists of a square-section pipe in which a two-dimensional bluff body and a strain gauge force sensor are placed. These two elements are separated from each other, unlike the majority of vortex apparatus currently available. The principle is based on the generation of a separated wake behind the bluff body. The volumetric flow-rate measurement is done by counting vortices using a flat plate placed in the wake and attached to the beam sensor. By optimizing the geometrical arrangement, the search for a significant signal has shown that it was possible to get a quasi-periodic signal, within a good range of flow rates so that its performances are well deduced. The repeatability of the value of the volume of fluid passed for every vortex shed is tested for a given flow and then the accuracy of the measuring device is determined. This quantity is the constant of the device and is called the digital volume (Vp). It has the dimension of a volume and varies with the confinement of the flow and with the Reynolds number. Therefore, a dimensionless quantity is introduced, the reduced digital volume (Vr) that takes into account the average speed in the contracted section downstream of the bluff body. The reduced digital volume is found to be independent of the confinement in a significant range of Reynolds numbers, which gives the device a good accuracy.

Chin force in violin playing

Force generated between the left mandible of violinists and the chinrest of the violin was examined using a force-sensing chinrest developed in this study. A strain-gauge force sensor was built, and it was fixed between the violin's top plate and a chin cup. Fifteen professional/amateur violinists held the violin statically, played musical scales with different sound properties and sounding techniques, as well as an excerpt from a Max Bruch concerto. Peak and mean forces were evaluated for each task. In a separate experiment, lateral movement of the lower teeth due to different levels of voluntary chin force exertion was measured. Static holding forces observed were 15 and 22 N with and without the help of the left hand, respectively. Peak force increased from 16 N at soft dynamics to 20 N at strong dynamics during scales. The force further increased to 29 N with the use of vibrato technique and 35 N during shifts. Tempo and hand position did not affect the force. Playing a Bruch concerto induced a mean peak force of 52 N, ranging from 31 to 82 N among the violinists. The developed force-sensing chinrest could accurately record the generated chin force. Typical chin force to stabilize the violin during ordinary musical performance was less than 30 N, but it could momentarily exceed 50 N when technically demanding musical pieces were performed. The lateral shift of the mandible was fairly small (<0.4 mm) even with high chin-force exertion, possibly due to clenching of the molars.

Force feedback in a piezoelectric linear actuator for neurosurgery

Force feedback in robotic minimally invasive surgery allows the human operator to manipulate tissues as if his/her hands were in contact with the patient organs. A force sensor mounted on the probe raises problems with sterilization of the overall surgical tool. Also, the use of off-axis gauges introduces a moment that increases the friction force on the bearing, which can easily mask off the signal, given the small force to be measured. This work aims at designing and testing two methods for estimating the resistance to the advancement (force) experienced by a standard probe for brain biopsies within a brain-like material. The further goal is to provide a neurosurgeon using a master-slave tele-operated driver with direct feedback on the tissue mechanical characteristics. Two possible sensing methods, in-axis strain gauge force sensor and position-position error (control-based method), were implemented and tested, both aimed at device miniaturization. The analysis carried out was aimed at fulfilment of the psychophysics requirements for force detection and delay tolerance, also taking into account safety, which is directly related to the last two issues. Controller parameters definition is addressed and consideration is given to development of the device with integration of a haptic interface. Results show better performance of the control-based method (RMSE < 0.1 N), which is also best for reliability, sterilizability, and material dimensions for the application addressed. The control-based method developed for force estimation is compatible with the neurosurgical application and is also capable of measuring tissue resistance without any additional sensors. Force feedback in minimally invasive surgery allows the human operator to manipulate tissues as if his/her hands were in contact with the patient organs.

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.

2P2-K10 力センサを用いた子どものよじ登り行動センシングシステムの開発(デジタルヒューマン)

In this study, a computational model of child climbing behavior has been developed to prevent childhood injuries by changing environmental factors. This model is constructed by probabilistically modeling the relationships among product design parameters, child characteristics, and climbing behaviors based on observed behavioral data. Large scale behavioral data are needed to apply the behavior model to every day life environment. In this paper, a system for sensing child climbing behavior is developed using strain gauge force sensors installed under experimental boxes. This system simultaneously collects force sensor data and camera data during an experiment and enables to measure child climbing behaviors toward the boxes.