Showing papers on "Inductive sensor published in 2022"

Research on the Time Drift Stability of Differential Inductive Displacement Sensors with Frequency Output

Abstract: An edge displacement sensor is one of the key technologies for building large segmented mirror astronomical optical telescopes. A digital interface is one novel approach for sensor technologies, digital transformation and the Internet of Things (IoT) in particular. Frequency output sensors and inductance-to-digital converter (LDC) demonstrated significant advantages in comparison with conventional sensors with analog-to-digital converter (ADC) interfaces. In order for the differential inductive frequency output displacement (DIFOD) sensor to meet the high-stability requirements of segmented mirror astronomical telescopes, it is important to understand the factors for time drift of the sensor. This paper focuses on the investigation of key factors of sensor structure and material, signal conditioning and interface, and fixtures for time drift to permanently installed applications. First, the measurement principle and probe structural characteristics of the sensor are analyzed. Then, two kinds of signal conditioning and digitalization methods using resonance circuits and LDC chips are implemented and compared. Finally, the time drift stability experiments are performed on the sensors with different signal conditioning methods and fixtures under controlled temperature. Experimental results show that the magnetic shield ring effectively improves the sensitivity and quality factor of the sensors, the time drift stability of the sensor using the signal conditioning based on resonance circuits is better than that of the sensors using LDC chips, and the root mean square (RMS) of the sensor time drift meets the requirement of 0.01 μm/24 h. This study will help further development of high-stability of frequency output sensors and IoT-based systems for scaled-up applications in the future.

Design Optimization of PCB-Based Rotary-Inductive Position Sensors

Abstract: This paper introduces a novel methodology to optimize the design of a ratiometric rotary inductive position sensor (IPS) fabricated in printed circuit board (PCB) technology. The optimization aims at reducing the linearity error of the sensor and amplitude mismatch between the voltages on the two receiving (RX) coils. Distinct from other optimization techniques proposed in the literature, the sensor footprint and the target geometry are considered as a non-modifiable input. This is motivated by the fact that, for sensor replacement purposes, the target has to fit a predefined space. For this reason, the original optimization technique proposed in this paper modifies the shape of the RX coils to reproduce theoretical coil voltages as much as possible. The optimized RX shape was obtained by means of a non-linear least-square solver, whereas the electromagnetic simulation of the sensor is performed with an original surface integral method, which are orders of magnitude faster than commercial software based on finite elements. Comparisons between simulations and measurements performed on different prototypes of an absolute rotary sensor show the effectiveness of the optimization tool. The optimized sensors exhibit a linearity error below 0.1% of the full scale (FS) without any signal calibration or post-processing manipulation.

Co-advise: Cross Inductive Bias Distillation

Abstract: The inductive bias of vision transformers is more relaxed that cannot work well with insufficient data. Knowledge distillation is thus introduced to assist the training of transformers. Unlike previous works, where merely heavy convolution-based teachers are provided, in this paper, we delve into the influence of models inductive biases in knowledge distillation (e.g., convolution and involution). Our key observation is that the teacher accuracy is not the dominant reason for the student accuracy, but the teacher inductive bias is more important. We demonstrate that lightweight teachers with different architectural inductive biases can be used to co-advise the student transformer with outstanding performances. The rationale behind is that models designed with different inductive biases tend to focus on diverse patterns, and teachers with different inductive biases attain various knowledge despite being trained on the same dataset. The diverse knowledge provides a more precise and comprehensive description of the data and compounds and boosts the performance of the student during distillation. Furthermore, we propose a token inductive bias alignment to align the inductive bias of the token with its target teacher model. With only lightweight teachers provided and using this cross inductive bias distillation method, our vision transformers (termed as CiT) outperform all previous vision transformers (ViT) of the same architecture on ImageNet. Moreover, our small size model CiT-SAK further achieves 82.7% Top-1 accuracy on ImageNet without modifying the attention module of the ViT. Code is available at https://github.com/OliverRensu/co-advise.

Hybrid Magnetic–Inductive Angular Sensor with 360° Range and Stray-Field Immunity

Abstract: Magnetic and inductive sensors are the dominant technologies in angular position sensing for automotive applications. This paper introduces a new angular sensor: a hybrid concept combining the magnetic Hall and inductive principles. A magnetic Hall transducer provides an accurate angle from 0° to 180°, whereas an inductive transducer provides a coarse angle from 0° to 360°. For this novel concept, a hybrid target with a magnetic and inductive signature is also needed. Using the two principles at the same time enables superior performances, in terms of range, compactness and robustness, that are not possible when used separately. We realized and characterized a prototype. The prototype achieves a 360° range, has a high accuracy and is robust against mechanical misalignments, stray fields and stray metals. The measurement results demonstrate that the two sensing principles are completely independent, thereby opening the doors for hybrid optimum magnetic–inductive designs beyond the usual trade-offs (range vs. resolution, size vs. robustness to misalignment).

A Spring-Based Inductive Sensor for Soft and Flexible Robots

Abstract: The development of flexible and soft robots generates new needs in terms of instrumentation, as large encountered deformations require highly stretchable strain sensors. In this regard, we contribute to the adoption of inductive sensors by providing tools to model and exploit them and showing their relevance experimentally. First, strain estimation based on voltage measurement is proposed. Compared to direct inductance evaluation, the principle is easier to implement and opens the possibility to optimize the measurement performances by tuning the circuit components and interrogation frequency. The possibility of performing a single sensor calibration independently via the elongation mode during strain sensing is outlined. A detailed characterization is then performed, which shows that the sensor produces a low hysteresis of 0.1%, a precision in the order of 0.14%, and an accuracy of 0.9%. Finally, two proofs of concept are proposed: 1) the integration with a pneumatic artificial muscle (PAM) that demonstrates the added value of the sensor for a model-free precise control of a soft system and 2) the closed-loop control of a flexible bending manipulator using the inductive sensor. The performance in the closed-loop control is demonstrated, with a sensing element that is easy to integrate mechanically, strengthening its potential to be used as a structural element as well.

Development of inductive sensors for a robotic interface based on noninvasive tongue control

Abstract: Tongue based robotic interfaces have shown the potential to control assistive robotic devices developed for individuals with severe disabilities due to spinal cord injury. However, current tongue-robotic interfaces require invasive methods such as piercing to attach an activation unit (AU) to the tongue. A noninvasive tongue interface concept, which used a frame integrated AU instead of a tongue attached AU, was previously proposed. However, there is a need for the development of compact one-piece sensor printed circuit boards (PCBs) to enable activation of all inductive sensors. In this study, we developed and tested four designs of compact one-piece sensor PCBs incorporating inductive sensors for the design of a noninvasive tongue-robotic interface. We measured electrical parameters of the developed sensors to detect activation and compared them with a sensor of the current version of the inductive tongue-computer interface (ITCI) by moving AUs with different contact surfaces at the surface of the sensors. Results showed that, the newly developed inductive sensors had higher and wider activation than the sensor of ITCI and the AU with a flat contact surface had 3.5 - 4 times higher activation than the AU with a spherical contact surface. A higher sensor activation can result in a higher signal to noise ratio and thus a higher AU tracking resolution.

Research on the Influence of Coil LC Parallel Resonance on Detection Effect of Inductive Wear Debris Sensor

Abstract: The coil structure of the inductive wear debris sensor plays a significant role in the effect of wear debris detection. According to the characteristics of LC parallel resonance, the capacitor and coil are connected in parallel to make sensor coils in the LC parallel resonance state, which is beneficial to improve the ability to detect wear particles. In this paper, the mathematical model of output-induced electromotance of the detection coil is established to analyze the influence of the structure on the detection sensitivity and enhance the sensor’s current rate of change to the disturbance magnetic field, which is essential to resist noise interference. Based on the coherent demodulation principle, the AD630 lock-in amplifier is applied to the test platform to amplify and identify weak signals. In addition, experiments are designed to test the output signals of debris under the condition of different original output voltages of the sensor with a parallel structure. Meanwhile, the near-resonance state of the detection coil with LC parallel circuit is tested by output signal information. Results show that the sensor detection sensitivity will be effectively improved with the LC parallel coil structure. For the sensor structure parameters designed in this paper, the optimal raw output amplification voltage for abrasive particle detection is 4.49 V. The detection performance of ferromagnetic particles and non-ferromagnetic particles is tested under this condition, realizing the detection ability of 103.33 μm ferromagnetic abrasive particles and 320.74 μm non-ferromagnetic abrasive particles.

Investigation of PCB-based Inductive Sensors Orientation for Corona Partial Discharge Detection

Abstract: This paper presents an experimental investigation of two different printed circuit board (PCB) inductive sensors, with meander and non-spiral shapes, to assess their capabilities and best orientation for corona partial discharge (PD) detection. First, simulations with the Ansys HFSS software are performed in order to evaluate the equivalent electrical circuit of the two sensors and their 2d radiation patterns. The meander sensors presented a resonant frequency of 600 MHz, while it was around 1.1 GHz for the non-spiral. The 2d radiation pattern showed that better sensitivity is achieved when the inductive sensor is oriented 90 degrees with respect to the PD source. Experimental tests showed a peak-to-peak voltage of the PD signal detected by both sensors of around 14 mV when the orientation was 90 degrees with a main frequency around 35 MHz. The peak-to-peak voltage dropped to about 5.4 mV and 6.9 mV for the meander and the non-spiral sensors, respectively, with a main frequency of about 33.5 MHz, when the orientation was 0 degrees. The obtained PRPD patterns and the PD signal shapes were quite similar to those provided by a High-Frequency Current Transformer (HFCT) commercial sensor.

Addendum: Multiaxial resonant MEMS force sensor (2018 J. Micromech. Microeng. 28 105002)

Abstract: In this letter we present an MEMS Sensor to measure displacement in at least two directions. The sensor device is a resonant, Lorentz force driven and cross-shaped sensing structure whereas the measurement signal equals the change of the resonance frequency induced by the deformation of the sensor-frame. This device is a pre-study to implement the sensor in a two-dimensional micro manipulation system for which the team uses a micro system analyzer to detect the resonance frequencies of the different vibration modes. The sensor-frame deformation between 0.1 and 2 µm is generated by four piezo actuators. With this setup, the sensor achieves a sensitivity of up to 20 nm Hz−1. The device is fabricated from a 100 mm SOI wafer with standard CMOS processes and has two Pt1000 elements integrated on the device layer to compensate any effects caused by thermal extension of the structure or temperature induced changes of material parameters.

A Linear Eddy Current Speed Sensor for Speed Measurement of Conductive Objects

Abstract: This article presents the novel structure of an eddy current sensor for linear speed measurements. The sensor has one excitation coil and two pairs of antiserially connected pick-up coils, which are located inside and outside the excitation coil. The design and modeling of the sensor are considered with an air core and with a magnetic yoke (core) to compare their performances in terms of sensitivity and nonlinearity error. The experiments and the analysis are performed at different excitation frequencies and speeds. A novel three-dimensional analytical method is developed and utilized for parametric analysis and for the design of this sensor. The simulation results are compared with measurements up to 16.7 m/s (60 km/h). The achieved nonlinearity error is as low as 0.3%.

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

Abstract: 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.

A Novel Inductive Angular Displacement Sensor With Multi-Probe Symmetrical Structure

Abstract: This articledevelops a novel probe-type inductive angular displacement sensor based on time-grating, which is suitable for large-diameter hollow rotary table position detection of the heavy-duty machine tools. It abandons the traditional sensor precise marking lines in spatial domain, and integrates the tested mechanical component with the sensor, which realizes the angular displacement measurement directly. The sensor is divided into three parts: 1) a permalloy probe, which is adopted the simple structure to reduce the assembly errors; 2) a 45-steel rotor, which is a standard spur gear in a heavy-duty machine tool rotary table transmission system; 3) three groups of copper coils, which include sinusoidal coils, cosine coils and inductive coils. The theoretical model of angular displacement measurement is derived by means of mathematical equation in detail. Then the feasibility of the sensor structure is verified by finite element simulation. After that, a sensor prototype is built and tested in the laboratory, showing that the sensor has an original error of ±0.018° (approximately ± $64^{\prime \prime }$ ) over a full 360° range. The error analysis found that the systematic error is the main component. As a result, the mechanical structure and angular displacement algorithm of the sensor are optimized, which can significantly reduce the original errors of the sensor. After optimization, the final accuracy of the sensor is within ±0.0012° (approximately ± $4.4^{\prime \prime }$ ) in the range of 0°–360°.

Influence of structural parameters on the static performance of self-inductive radial displacement sensor

Abstract: The self-inductive displacement sensor has been widely used in active magnetic bearing systems for its excellent performance. However, there is a lack of studies on this sensor’s output characteristics according to the voltages directly from the coils, not from the processing circuit. Therefore, it needs to be further studied to improve the sensor theory and provide technical guidance for the sensor design. This paper analyzed the sensor’s working principle and designed some radial sensors with different nominal air gaps and coil turns. Then the effects of the nominal air gap and coil turns on the sensor coil’s output voltage and sensitivity were studied through the finite element simulation and experiments. According to the results, the number of coil turns could hardly affect the sensor’s static output voltage and sensitivity. The sensor sensitivity in the linear measurement range is proportional to the reciprocal of the nominal air gap length, but it is much less than the theoretical value. The results of this paper provide a valuable reference for the theoretical analysis and structural design of the self-inductive displacement sensor.

Research on the influence of inductive wear particle sensor coils on debris detection

Abstract: The debris detection characteristics of the inductive wear monitoring are researched by the method of combining theoretical research and simulation analysis in this paper. The mathematical model of the change in inductance is established based on the change in the coil magnetic field by the abrasive particles. By the COMSOL simulation software, the physical model of the three-coil wear monitoring is established, and the influence of the coil structure parameters on the output induced electromotance is compared and analyzed, resulting in the optimization of the coil parameters. For metal particles with different properties and sizes, the changes in the induced electromotance during the process of passing through the coil are analyzed, obtaining the mapping relationship between each particle size and the output induced electromotance. The simulation results show that the output voltage corresponding to the particles is related to the coil structure parameters, and the larger the particle size, the larger the output voltage. Finally, through experiments, the designed sensor coil structure has been proved to have a better detection effect on metal particles, realizing the detection of ferromagnetic abrasive particles above 100 µm and non-ferromagnetic abrasive particles above 200 µm.

Influence of Dimensions on Detection Sensitivity of Position Detection Sensor for Railway Vehicle

Abstract: One of the technologies for detecting the position of railway vehicles is a sensor that obtains the position information by detecting a metallic marker laid on the track and an electromagnetic induction coil mounted on a railway vehicle. The maximum distance between the marker and the coil is 250 mm. One of the methods to improve the detection sensitivity is to increase the size of the excitation coil or to increase the excitation frequency. However, these methods have the problem of limiting the installation area and radiating electromagnetic waves to other equipment. Therefore, under the condition that the size and frequency of the excitation coil are constant, we evaluate the effect of the size of the coil and the metallic marker on the detection sensitivity and proposed a method to improve the detection sensitivity of the position detection sensor for railway vehicle.

An Eddy-Current-Based Angle Sensor With a Minimally Modified Shaft as a Sensing Element

Abstract: Eddy current sensors are an attractive choice due to their high resolution, reliability, and durability in harsh environments while being able to measure in a non-contact manner. This paper presents a novel design to realize a thin eddy current-based angle sensor. It is realized by converting the shaft, whose rotation angle is to be measured, into the sensing element. The modification to the shaft is minimal; a small surface groove is introduced without affecting the mechanical strength. The stationary part of the sensor consists of two layers of flexible square-planar coils. Depending on the angular position of the shaft, the inductances of the planar coils get modified. These are measured using a specially designed circuitry, optimized for this sensor. The output for the entire circle range (360∘) is derived from the inductance values of each coil using a successive approximation algorithm developed for this purpose. Finite element analysis was employed to design the sensor and analyze the axial/radial misalignment of the rotor. A sensor prototype was built and tested. The output showed a resolution of 0.1∘ and the worst-case linearity error of 0.9%. The prototype sensor dimensions are designed to fit in a standard steering column. The proposed sensor is thin, easy to manufacture at low cost, tolerant to axial vibration by design, and has a 360∘ sensing range.

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

Abstract: 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.

MHz range frequency based sensor for Magnetic Particle Detection

Abstract: <p>Design of rapid technique for magnetic particles detection based on inductive sensing is described in this paper. A fabricated 3D coil, oscillating at few MHz range frequencies, is used as a sensing element with its associated electronics for inductance measurements. Phase locked loop is used for sensor stability and accuracy in the detection system. The induced magnetic field, due to the presence of magnetic particles on the coil, alter the coil inductance and accordingly the output frequency signal. Different concentration and number of magnetic beads (µm to nm sizes) were tested with the sensor while oscillating at two different resonance frequencies and the results were compared together. </p>

Smart Bin for Waste Management

Abstract: Abstract: The aim and object of this project is to prepare a Smart Bin for the collection of Metal and non metal so that they can be easily separated. What this project will do is, Separate the metal and non metal from the waste. Metal will be detected by the help of Proximity Inductive sensor and will be separated as metal by the help of servo motor.

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

Abstract: 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.

Inductive XY calibration method for multi-material fused filament fabrication 3D printers

Abstract: In this work an optical and inductive calibration procedures for calibrating multi-material fused filament fabrication 3D printers in the x and y directions is presented. The inductive calibration is based on the principle that the inductance of a detection coil placed on the print bed changes when the (metallic) extrusion nozzle passes it. This calibration method shows a repeatability of up to 2 µm. To determine the accuracy of this calibration method, another calibration method is proposed that directly measures the position of the deposited material. During this alternative process, a calibration structure is printed on an A4-format sheet of paper using every tool. The paper is subsequently scanned using a digital scanner, and the resulting image is analyzed using an image-processing script. Using this method as a reference, it was determined that the inductive method has an accuracy of approximately 45 µm. For applications where this accuracy is sufficient, the inductive method provides a fast solution that requires little to no user interaction. For more demanding applications, the optical calibration might be the better choice, since it is more time-consuming but yields a more accurate solution. It is expected that the accurate calibration of tool offsets will reduce both the chance of poor adhesion between materials and the mixing of filaments due to local over- and under-extrusion at material interfaces.

Simulation and measurements of a rotary inductive position sensor

Abstract: In this work a method for the fast simulation of a rotary inductive position sensor with the Surface Integral Method in order to predict the non linearity error of the sensor is provided. Experimental analysis shows the effectiveness of the method and the effect of the rotation speed on the receivers.

Study on the Effect of Eddy Current for Inductive Angle Sensor with Resonant Structure

Abstract: Planar inductive position sensor based on PCB has the advantage of low cost and reducing the error caused by winding manufacturing. For inductive sensor with resonant structure, the undesired eddy current caused by conductive shell influences the amplitude and carrier phase of output signals when the sensor is integrated in the motor. This change affects signal demodulation feasibility of the sensor and reduces the signal-to-noise ratio. For this problem, the influence of ferromagnetic materials and eddy current is here discussed. A modified coupling model of multiple coils considering eddy current is proposed to describe a system with modulation characteristics, and the corresponding equivalent circuit equations are established. A prototype is manufactured to verify the performance of the proposed design, and the ferrite is used to suppresses the coupling between the sensor and metallic environment. According to the experimental results, the sensor signal demodulation is achieved properly, and the linear angle estimation realized at a uniform speed.

Design and Development of Inductive Sensor Mini Trainer Based on Arduino

Abstract: Sensor and Transducer is one of the subjects that must be followed by students of the Automotive Engineering Department, Faculty of Engineering, Padang State University, which weighs 2 credits. In accordance with the RPS for the Sensor and Transducer Course, there are several types of sensors that are the subject of study, one of which is an inductive sensor. Inductive sensor applications are applied in the automotive world such as Crankshaft Position Sensor (CKP), Camshaft Position Sensor (CMP), Vilocity Sensor. To make it easier to understand each sensor applied in the automotive world, students are required to master the basic concepts of the inductive sensor. One of the ways to increase student competence in the field of inductive sensors is the use of teaching aids during the learning process. Inductive sensor learning media in the Laboratory at the Automotive Engineering Department still uses analog processors, to support the development of digital technology today, so the authors provide an alternative by making teaching aids in the form of an Arduino-based Inductive Sensor Mini Trainer. This study uses the Research and Development (R&D) method which consists of Define, Design, Development, and Desseminate. The assembled inductive sensor mini trainer was tested for accuracy, and repeatibility test as well as feasibility test from media experts and users. The results of the research on the product trials carried out, obtained an accuracy level of 96.21%, the sensor output has linearity, the repeatibility test is obtained with an average of 0.1%. The level of product feasibility from Media Experts, is 94.68% and 96.23% from Respondents. So it can be concluded that the Inductive Sensor Mini Trainer is very suitable to be used as a learning medium.

Inductive debris detection using common-mode rejection

Abstract: Debris feature is one of the important indicators that reflects the condition of mechanical wear. Timely and efficient debris detection has great significance for mechanical health management and fault diagnosis. However, under the actual working process, the inductive debris detector is susceptible to electromagnetic variations and mechanical vibration, which limits its detection sensitivity. This paper proposes an inductive debris detector using common-mode rejection to suppress the above interferences. First, a general model is established and the noise rejection principle is discussed based on common-mode rejection. Then, an inductive abrasive debris detector is designed based on the model. Finally, the performance of the sensor in standby state and working state is tested. The experimental results show that the detector using common mode rejection can effectively suppress external interference without weakening the detection signal and has great application potential.