Inductive Sensor Research Articles

Design and Characterization of Three-Axis High-Range Inductive Tactile Force Sensor Utilizing Magnetorheological Elastomer for Robotic Surgical Applications

This article presents a three-axis inductive tactile force sensor utilizing a magnetorheological elastomer (MRE) marker for inducing inductance change in square-shaped coils, in response to an input force. The sensor consists of copper coils on a printed circuit board (PCB) and a patterned elastomer layer between the marker and coils. The proposed configuration of the coils reduces the mechanical crosstalk between the applied three-axis forces, thus decoupling the force axes. Finite-element method (FEM)-based analyses are carried out to optimize the sensing gap between the coils and the marker. To observe the effect of the elastomer material on the sensor performance, two types of silicone rubbers, Ecoflex-30 and RTV-528, are used to make the patterned elastomer and the marker. The sensor with Ecoflex-30 elastomer can measure forces up to 25 N in normal and 2.5 N in shear directions, whereas the sensor with RTV-528 elastomer has a higher force range of up to 30 N for normal and 6 N for shear directions but has a lower sensitivity. A resolution of 12.71, 7.96, and 6.61 mN is achieved with Ecoflex-30, whereas for RTV-528, the force resolution is 76.52, 11.7, and 23.98 mN for normal, shear, and angular shear directions, respectively. The hysteresis error for the proposed sensors is 7.2% and 5.3% for Ecoflex-30 and RTV-528 elastomers, respectively. The proposed inductive tactile force sensor can be used in a wide range of robotic surgical applications for sensing multidirectional forces with better resolution and low hysteresis error.

Simplifying Capacitive Sensor Readout Using a New Direct Interface Circuit

Direct interface circuits (DICs) are efficient for reading resistive, capacitive, or inductive sensors in a digital format. The simplest DICs consist of just a few passive elements that connect a digital processor (DP) to a sensor. When reading capacitive sensors, one or several calibration capacitors and/or several charging and discharging cycles are needed to make the estimation, and the result usually requires complex arithmetic operations. This article presents a new type of capacitive DIC that is simple in terms of hardware, needing only two resistors of known value and the DP in order to make the capacitance estimation. In addition, the reading method requires a single sensor charging and discharging cycle, which reduces acquisition time and power consumption. Two time measurements are taken during the discharge, which, through a linear transformation of their subtraction (using two constants stored in the DP), give the value of the capacitance. These arithmetic operations are easily implemented on any DP and consume fewer resources than the divisions required on other capacitive DICs. The design has been tested for a wide range of capacitances (from 100 pF to 561 nF), including the value of several capacitive sensors. The average relative error for the entire range is 0.41%, the linearity errors are below 0.3%, and the minimum signal-to-noise ratio (SNR) value is 64 dB.

Analiza merenja fizičkih veličina kod balističkih ispitivanja primenom različitih tipova senzora

Measurements of recoil and counter-recoil movement in weapons are essential in order to optimize ballistic performances, to ensure safety during firing, to improve the accuracy and the effectiveness of the weapon during its life cycle and to guide design and development work. From this, the present work focuses on contact-based measurements of the counter-recoil movement of the D30J 122 mm howitzer using two inductive sensors, namely, displacement sensor and acceleration sensor. The measurements from the displacement sensor were used to calculate the velocity and acceleration of the counter-recoil by derivation and those of the acceleration sensors were used to calculate the velocity and displacement of the counter-recoil by integration. The comparison between the measured and calculated results obtained from the two sensors shows a very good similarity in form of variation and in values, which validates the applied experimental approach in this work and confirms the accuracy of both measurement methods.

High-Sensitivity Signal Processing Circuit Integrated Coil Antenna Sensor Toward Measurements of the Water Fraction in the Oil–Water Two-Phase Flow

The measurement of water fraction in the oil-water two-phase flow is important for the processing control of oil production. In this paper, a coil antenna based high-sensitivity inductive sensor is proposed to measure the water fraction in the oil-water two-phase flow in real time. It employs a wire-wound coil antenna, an associated signal processing circuit, and a sensor fixture to support and hold them. The change of water fraction in the flow causes the change in equivalent inductance of the coil antenna. By adding external capacitors to the coil antenna, a parallel inductance-capacitance resonant circuit is formed, and it efficiently converts the inductance change to the voltage change, which improves the measurement sensitivity. The specified signal processing circuit picks up the voltage change, realizes the AC/DC signal conversion, and amplifies DC small signals. Then the measurement theory is analyzed, and the transduction model of coil inductance change to voltage output is given. To verify the proposed inductive sensor, a prototype is fabricated, and a measurement platform is built in which the generated oil-water flow has a water fraction ranging from 0 to 100%. Experimental results show that the proposed inductive sensor can measure the water fraction in real time with a measurement resolution of 1% and a measurement standard deviation of less than 1.2%.

Real Time Automation and Ratio Control Using PLC & SCADA in Industry 4.0

Industrial Control Systems (ICS) and SCADA (Supervisory Control and Data Acquisition) systems play a critical role in the management and regulation of critical infrastructure. SCADA systems brings us closer to the real-time application world. All process and equipment control capability is typically provided by a Distributed Control System (DCS) in industries such as power stations, agricultural systems, chemical and water treatment plants. Instead of control through DCS, this paper proposes a SCADA and PLC (Programmable Logic Controller) system to control the ratio control division and the assembly line division inside the chemical plant. A specific design and implementation method for development of SCADA/PLC based real time ratio control and automated assembly line system in a chemical plant is introduced. The assembly line division is further divided into sorting stage, filling stage and the auxiliary stage, which includes the capping unit, labelling unit and then the storage. In the ratio control division, we have defined the levels inside the mixer and ratio of the raw materials through human machine interface (HMI) panel. The ratio of raw materials is kept constant on the basis of flow rates of wild stream and manipulated stream. There is a flexibility in defining new levels and the ratios of the raw materials inside the mixer. But here we taken the predefined levels (low, medium, high) and ratios (3:4, 2:1, 2:5). Control valves are used for regulating the flow of the compositions. In the assembly line division, the containers are sorted on the basis of size and type of material used i.e., big sized metallic containers and small sized non-metallic containers by inductive and capacitive proximity sensors. All the processes are facilitated with laser beam type or reflective type sensors on the conveyor system. Building a highly stable and dependable PLC/SCADA system instead of Distributed Control System is required to achieve automatic management and control of chemical industry processes to reduce waste manpower and physical resources, as well as to improve worker safety.

High-frequency models of inductive sensors for recording of partial discharges in the insulation of electrical equipment

High-frequency models of inductive sensors for recording of partial discharges in the insulation of electrical equipment

Hand Gesture Recognition Pad Using an Array of Inductive Sensors

Gesture recognition is a field of study within human-computer interaction technology and is used in an increasing number of applications. So far, the systems designed for gesture recognition have been able to sense multiple static and dynamic gestures. However, they suffer from some limitations. This study introduces a novel sensing pad system consisting of an array of inductive sensors which can recognize and differentiate specific static hand gestures through machine learning algorithms. It is designed to be a non-contact apparatus where the gestures made by a user can be perceived by the system. It uses five coils, one for each finger, and can sense the fingers that are unfolded while making a particular gesture. Ten volunteer users participated in this study. Ten gestures, numbers 1-10 of the American Sign Language are chosen to be tested upon, 10 times each for every user. The responses from the sensing coils were measured via a data acquisition board and sent to the PC for processing. A total of 1000 responses were recorded and processed using machine learning algorithms which provided an accuracy of 98.7% using 5-fold cross-validation (5F-CV) and 97.3% using leave-one-subject-out CV (LOSO-CV) proving that the system can successfully distinguish hand gestures instantly.

Study on the Three-Axis Sensory Inductive Sensor for Pedestrian Analysis of Diabetes Patients

Study on the Three-Axis Sensory Inductive Sensor for Pedestrian Analysis of Diabetes Patients

Индукционный метод локализации фронта кристаллизации

The paper describes the development and testing of an inductive sensor designed for determining the position of the solidification front of electricallyconductive melts. The operation of the sensor is based on the eddy current transducer principle. We compared induction and ultrasonic methods of localizing the solidification front of a gallium alloy on a model problem of directional solidification of liquid metal in a flat vertical layer. The principles of the induction method are described, its ap-plicability is shown, the measurement error has been found.

An Enhanced Inductance-to-Digital Converter for Single-Element and Differential-Type Inductive Sensors With Automatic Offset Eliminator

An Enhanced Inductance-to-Digital Converter for Single-Element and Differential-Type Inductive Sensors With Automatic Offset Eliminator

PCB-Based Planar Inductive Loops for Partial Discharges Detection in Power Cables

Partial discharge (PD) diagnosis tests, including detecting, locating, and identifying, are used to trace defects or faults and assess the degree of aging in order to monitor the insulation condition of medium- and high-voltage power cables. In this context, an experimental evaluation of three different printed circuit board (PCB)-based inductive sensor topologies, with spiral, non-spiral, and meander shapes, is performed. The aim is to assess their capabilities for PD detection along a transmission power cable. First, simulation and experimental characterization are carried out to determine the equivalent electrical circuit and the quality factor of the three sensors. PD activity was studied in the lab on a 10-m-long defective MVAC cable. The three PCB-based sensors were tested in three different positions: directly on the defective cable (P1), at a separation distance of 10 cm to 3 m (P2), and on the ground line (P3). For the three positions, all sensors' outputs present a damped sine wave signal with similar frequencies and durations. Experimental results showed that the best sensitivity was given by the non-spiral inductor, with a peak voltage of around 500 mV in P1, 428 mV in P2, and 45 mV in P3, while the meander sensor had the lowest values, which were approximately 80 mV in P1. The frequency spectrum bandwidth of all sensors was between 10 MHz and 45 MHz. The high sensitivity of the non-spiral inductor could be associated with its interesting properties in terms of quality factor and SFR, which are due to its very low resistivity. To benchmark the performance of the designed three-loop sensors, a comparison with a commercial high-frequency current transformer (HFCT) is also made.

ISO26262-Compliant Inductive Long-Stroke Linear-Position Sensors as an Alternative to Hall-Based Sensors for Automotive Applications.

To ensure safety, vehicle companies require position sensors that maintain accuracy and avoid target loss even in harsh automotive environments. Most vehicle position sensors are Hall-based, but even improved gradiometric 3D Hall sensors using the arctangent operation are vulnerable to external magnetic fields (EXMFs) and encounter difficulty at long-stroke (LS) positions. An ISO26262-compliant inductive position sensor (IPS) employing a 3.5 MHz-induced magnetic field source (much higher in frequency than vehicle-environment EXMFs) is proposed in this study as an alternative. To meet the safety goal, a threshold LS distance of 12 mm was set. Then the IPS was compared to existing Hall-based sensors. The B field of the existing 3D sensor was weak at LS and the airgap between sensor face and magnet target caused a large error in accuracy, whereas the IPS was not affected by LS. Because of its high excitation frequency, the IPS was also largely unaffected by EXMFs, as was demonstrated by ISO11452-8 and 0.1 T immunity tests. The proposed IPS outperformed existing 3D Hall sensors, achieving stable accuracy within ±0.85% for different airgaps (1.5-2.5 mm) and proving robust to magnetic and LS effects.

Customized Design of Inductive Sensor for an Early Detection of Cracks in Indian Rail Transport

The objective of this paper is to provide a solution to a serious issue in today’s world of transportation through railways. The practice to examine the flaws which leads to serious effects in rail track is rail inspection. Among the world countries, Indian railways are the fourth-longest, but when it comes to reliability and safety it lags to provide world standard. As a result, if the track is damaged, it leads to severe loss of valuable human lives and property. This derailment in tracks is caused due to cracks in the rails. Therefore, an early crack detection and protection system is required to save the lives. This paper proposes a customized design of an inductive transducer and crack detection system on railroad tracks to avoid the train accidents. Existing method uses the manpower to identify the cracks and this involves human errors. So, the drawbacks in the existing method can be reduced by the automatic system. Customized inductive sensor is designed and developed using ANSYS. A scaled down model of a cart is fabricated and the inductive sensor is assembled at beneath surface of the cart. The track is acting as a part of the magnetic core for the inductive sensor and voltage is induced in the sensor. The sensor voltage is calibrated to distinguish the magnitude of voltage from the normal to crack.

Parasitic Capacitance Associated With Inductive Sensors Used in MIT Imaging

Magnetic induction tomography (MIT) has recently been accomplished using a single inductive sensor, but under the assumption that it behaves as an ideal inductor. When performing a scan with a sensing coil that typically consists of a collection of concentric circular printed circuit board (PCB) copper traces connected in series, small amounts of parasitic capacitance arise that contribute to measured tank circuit loss. Results of this work quantify the magnitude of parasitic capacitance and associated losses. For current inductive sensors, capacitance-related loss is shown to diminish considerably when the coil is positioned more than ~2 cm from a target boundary. Recognizing that single-coil MIT scans generally position the coil within 2 cm of a target boundary, a correction is proposed, which enables a more accurate measurement of true inductive loss. Previously published scan data over agarose phantoms are then reexamined to show the negative impact on imaging fidelity that results when capacitance-related losses are ignored. Image comparisons are made using full 3-D image reconstruction, demonstrating that failure to compensate for parasitic capacitance loss can degrade image fidelity.

Aspects of Foreign Object Detection in a Wireless Charging System for Electric Vehicles Using Passive Inductive Sensors

If the energy transfer for charging the traction battery of an electric vehicle takes place wirelessly and with inductive components, the active area of the charging system must be monitored for safety reasons for the presence or intrusion of metallic objects that do not belong to the charging system. In the past, different concepts for such monitoring have been described. In this paper, passive inductive sensors are used and characterized based on practical measurements. With this type of sensor, the detectability of metallic foreign objects is very closely related to the characteristics of the magnetic field of the charging system. By optimizing the geometry of the sensor coils, the authors show how foreign object detection can be improved even in areas with low excitation of the foreign objects and the sensor coils by the magnetic field. For this purpose, a charging system, with which charging powers of up to 10 kW have been realized in the past, and standardized test objects are used. Furthermore, the thermal behavior of the metallic test objects was documented, which in some cases heated up to about 300 °C and above in a few minutes in the magnetic field of the charging system. The results show the capability of passive inductive sensors to detect metallic foreign objects. Based on the measurements shown here, the next step will be to simulate the charging system and the foreign object detection in order to establish the basis for a virtual development and validation of such systems.

Realtime Filtering of Waste Separate Equipment in Irrigation Channels

There are still many people who are not aware of disposing of waste in its place, including littering, one of which is in irrigation canals which can clog the channels and the many types of waste that can be found. To reduce waste in irrigation canals, an automatic waste separator was made. This automatic waste separator aims to transport waste in irrigation canals using two stages of conveyors, namely conveyor 1 for conveying lines from under water and conveyor 2 for waste separation lines, after which the waste is separated. according to the category, namely by using an inductive proximity sensor for Metal Waste and will be separated by using a servo motor, for non-metallic waste will be allowed to run on conveyor 2 then the waste is put into a trash can which can be monitored by ultrasonic sensors to see the height of the contents of the bin the trash. Monitoring this garbage separator uses the NodeMCU ESP 8266 WIFI as a connector with the BLYNK application to see whether the contents of the trash can are full or not by the cleaning officer on duty then the full trash can will be replaced with an empty trash can with monitoring control via BLYNK.

Structure and operating algorithms of the system for monitoring of the shaft’s axial dis-placement in combined journal-and-thrust bearing of the turbo-pump unit of liquid-propellant rocket engine NK-33

The problem of early wear diagnostics of the combined journal-and-thrust bearing of the turbo-pump unit of the liquid-propellant rocket engine NK-33 is considered. The main purpose of the diagnostics is to identify the initial stage of the bearings intensive wear. This allows to detect timely the catastrophic destruction of the unit and to prevent the development of emergency destruction of the power plant in general. The significant limitation of the appropriate diagnostic methods was the strict requirements of the inadmissibility of any changes on the number and dimensions of the sensors used in the product body while the existing functions of the turbopump rotor rotation speed monitoring should remain unchanged. The authors proposed a solution based on the replacement of the inductive RPM sensors that are currently used in the turbopump unit parameter monitoring systems with single-coil eddy current sensors with sensitive elements in the form of a conductor segment. This approach made it possible to monitor the axial displacement of the shaft in the combined journal-and-thrust bearing associated with the wear of the assembly and to keep the function of the measuring of the turbopump shaft rotational speed unchanged. The article provides a brief description of the implemented approach to early diagnosis of the condition of the bearing assembly of the NK-33 turbopump unit based on the measurement of the axial displacement of the shaft in the bearing. The technical solutions that implement the approach are based on the use of original single-coil eddy current sensors of a special design with shifted sensing elements, the non-standard converters of their output signals in combination with standard analog-to-digital converters (external modules of the Russian-made L-Card E14-440 ADC) and a PC that provides the control of the data aquisition, processing and visualization. A structural and functional scheme of the control system and its generalized operation algorithm are proposed.

Study and Design of Ratiometric Inductive Position Sensors Using Area-of- Overlap Functions

This article presents a theoretical study of an absolute, ratiometric inductive position sensor (IPS) based on eddy currents. The aim is to describe the working principle of the sensor, having as key components a transmitting coil, the receiving coils, and the conductive target, by introducing area-of-overlap functions. We show that each target–receiver pair needs the adoption of a different reconstruction formula for the identification of the target position, whereas in the literature the usual inverse tangent function is applied for every possible pair. Then, we seek the target–receiver pair that maximizes the amplitude of the induced voltages on the receivers. The results show that to achieve the maximum value of the induced voltages, the best choice is to have a rectangular target and rectangular receivers. To verify the theory, a simulation and optimization method has been applied to the rectangular receiver coils on two rotary IPS realized with printed circuit board (PCB) technology. Measurements performed on the prototypes have shown an increment of the induced voltage of more than 57% with respect to the commonly used sinusoidal receivers. However, a linearity error of 1.5%FS is obtained by using the inverse tangent reconstruction formula. When using the formula provided by the theory, the linearity error becomes 0.6%FS for the nonoptimized prototype and below 0.15%FS for the optimized one.

Research on a Wireless Temperature Measuring Device Using Inductive Power

With the advancement of urban construction, more and more distribution network lines are changed from overhead lines to cable lines. Currently, the distribution network cable connection generally adopts the European or American cable elbow. If the temperature changes inside the cable elbow can be monitored in time, it will help to find the hidden fault of the cable elbow in time and improve the safe operation level of the power grid. In this paper, the online temperature measurement device of distribution network cable is discussed and researched, and a contact-type inductive wireless temperature measurement sensor suitable for the elbow joint of distribution network cable is designed. The sensor not only can accurately measure temperature, but also has the characteristics of a convenient communication network, safe and reliable information, and strong insulation ability, which is suitable for large-scale promotion and application.

Design and Validation of a Variable Reluctance Differential Solenoid Transducer With an Ironless Stator

This article presents the design methodology, simulation results, and experimental results of a novel variable reluctance differential solenoid transducer (VRDST). The new ironless-stator VRDST (ISVRDST) is designed to mitigate the practical challenges inherent in the VRDST while maintaining its beneficial features compared to other linear inductive differential position sensors. The ISVRDST uses an air stator to reduce cost and increase compactness. FEA and Simulink simulations are used to predict the performance of the ISVRDST and a proof-of-concept prototype is designed to experimentally validate the simulation results. Like the VRDST, the ISVRDST is designed to utilize a complementary filter to fuse a low-speed position measurement with a high-speed velocity measurement, resulting in a single wide-bandwidth position measurement. The experimental results of the prototype ISVRDST prove that it is capable of robustly performing and fusing the two measurements utilized by the VRDST. In addition, the analytically predicted error of the fused measurement is found to be less than 1% different than the actual error relative to a high-precision laser vibrometer. When compared to the VRDST, the ISVRDST prototype is found to have a stroke-to-length ratio that is nearly four times greater and a cost that is over 100 times lower.