Linear Position Sensor Research Articles

FACTORS INFLUENCING THE EFFICIENCY OF MODERN ELECTRO-EROSION PROCESSING

The article describes the factors of increasing the efficiency of processing products on EDM equipment. due to the use of linear drives with high dynamic accuracy. Also, the inter-electrode gap in the processing zone, its influence on optimal energy regimes and maximum material removal was investigated in the work. The electrode is fed into the spark formation zone 5-10 times more often, the relative duration is several times longer than in machines with KGP drives. Sludge removal due to the pumping effect from rapid movements of the electrode instead of pumping. The use of linear motors, servo drives, precision linear position sensors, devices for automatic wire feeding, hole search, wire breakage prevention - will increase the productivity of wire-cutting processing by 40-100%.A comparative analysis of the performance of parts processing on equipment with the use of linear and KGP (ball-screw pairs) drives was carried out.

Laboratory study of the effect of installation parameters on the lateral behaviour of monopiles in sand

Monopiles are the predominant type of foundation used for offshore wind turbines. The increase in size of monopiles and the stricter environmental regulations in terms of underwater noise levels has motivated the development of alternatives to the conventional impact-driving method of monopile installation. One of the alternatives is the (axial) vibratory installation, which has been previously studied in field [1, 2, 4] and laboratory [3, 5] conditions. However, there is limited knowledge on the effects of vibratory installation (and how these effects differ from those caused by impact-driving) on the lateral response of monopiles.
 This extended abstract presents the results of an ongoing Join Industry Project (SIMOX – Sustainable Installation of XXL Monopiles) which aims at comparing different installation methods from the point of view of driveability, noise emissions and lateral response. The present abstract particularly focuses on the lateral response of monopiles. As a first step towards the large-scale onshore field tests to be executed in 2023, a laboratory study was conducted at the Water-Soil Flume at Deltares, in Delft (NL), which consists of a tank with 9.0 m of length, 5.5 m of width and 2.5 m of depth, with a multipurpose wagon on rails above it (Figure 1). The tank was filled with saturated Sibelco S90 sand up to a height of 2.4 m in compacted layers of 50 cm.
 The experimental programme consisted of 4 batches (batches 1, 2 and 3 with dense sand and batch 4 with medium-dense sand) in which piles of diameter D = 32 cm, embedded length L = 1.5 m and wall thickness t = 4 mm or 10 mm were installed and loaded laterally. While batch 1 focused on driveability aspects, in the other three batches 8 piles were installed (per batch) and subsequently subjected to lateral loading. The centre-to-centre distance between piles was 8D in the loading direction and 6.5D perpendicular to the loading direction. The distance between the piles and walls of the tank was 4.3D. All distances were larger than the minimum distances recommended in the literature [6]. The piles were installed with two different methods: vibratory-driven, using a hydraulic vibro-hammer APE-23 with an eccentric moment of 1.3 kg.m, and impact-driven, using a dropping weight impact-hammer HL750. For each method, selected installation parameters were varied, namely the vibratory frequency and lowering speed of the crane for
 vibrated piles, and dropping mass and fall height for the impact-driven piles. Lateral loading was applied at the pile head by means of an in-house built lateral loading device consisting of an electric motor connected to a spindle. The lateral displacements were measured by a magnetostrictive linear position sensor, independent of the lateral loading system. The loading regime consisted of an initial monotonic loading up to 25% of Hult (where Hult is defined as the load at which the pile exhibits a displacement of 0.1D at ground level – obtained from 3D FE analyses), followed by cyclic loading (1000 cycles for most piles) and a final monotonic stage up to the maximum load.
 The different combinations of lowering speeds of the crane (low, high) with the different frequencies of the vibro-hammer (low, high) led to different types of vibratory installation: crane controlled or free hanging. Under crane-controlled installation, the full weight of the pile-hammer system is sustained by the overhead crane, hence the crane load measured by a load cell oscillates around the static weight of the pile-hammer system. Under free-hanging conditions, on the other hand, the load taken by the crane is zero, meaning that the weight of the pile-hammer system is fully taken by the soil – both by shaft friction and tip resistance.
 The results in dense sand showed that the initial monotonic response of the piles is affected by the vibration mode, and not by the installation frequency or penetration speed alone. While the crane-controlled vibrated piles exhibited lateral stiffness similar (i.e. slightly lower) to the impact-driven piles, the free-hanging vibrated piles showed markedly lower lateral stiffness compared to the other piles. The softer behaviour observed for these piles could be attributed to various reasons, such as the difficulty in controlling the pile verticality during installation. For all free hanging piles, inclination was observed approximately half-way through installation, which was corrected in the final part of installation. The exact inclination during installation was not measured, which will be done in the onshore field tests. The test results showed, however, that during cyclic loading the differences in lateral stiffness decrease, i.e. the softest piles in the initial monotonic stage were the ones that exhibited the largest gain in lateral cyclic stiffness, whereas the stiffest piles in the initial loading stage were the ones with the smallest increase in stiffness during cyclic loading.

Resonator Arrays for Linear Position Sensors

A contactless position sensor based on an array of magnetically coupled resonators and an external single coil cell is discussed for both stationary and dynamic applications. The simple structure allows the sensor to be adapted to the system in which it is installed and can be used to detect the positions of objects in motion that bear an external resonator coil that does not necessitate a supply. By exploiting the unique behaviour of the array input impedance, it is possible to identify the position of the external resonator by exciting the first array cell with an external voltage source and measuring the resulting input current. The system is robust and suitable for application in harsh environments. The sensitivity of the measured input impedance to the space variation is adjustable with the definition of the array geometry and is analysed. Different configurations of the array and external resonator are considered, and the effects of various termination conditions and the resulting factor of merit after changing the coil resistance are discussed. The proposed procedure is numerically validated for an array of ten identical magnetically coupled resonators with 15 cm side lengths. Simulations carried out for a distance of up to 20 cm show that, with a quality factor lower than 100 and optimal terminations of both the array and external coil, it is possible to detect the position of the latter.

Perancangan dan Pembuatan Data Acquisition Device Sebagai Sistem Akuisisi Data untuk Kendali Mobil Formula Student

Data Acquisition Device (DAQ) is an electronic component used in formula student vehicles. To optimize the performance of the formula student vehicle and its driver, it is necessary to analyze and monitor the data acquisition system. Parameters acquired on the car include the position of the brake pedal/throttole and wheel speed.DAQ system has 5 input channels namely 3 analog input pins and 2 digital input pins, and 3 output channels, which is the controller pin, fault pin, and brake light pin. The DAQ system in this research is designed and made using Teensy 3.6, a signal conditioning circuit consisting of an RC low pass filter, voltage follower, non-inverting amplifier, and logic level shifter. DAQ system uses CANBUS to read and process sensor data. DAQ system can acquire data from the KTC Linear Motion Position sensor PZ-12-A-50P with an accuracy value of 99,91%; Hall-effect Rotary Position sensor RTY120LVNAX with an accuracy value of 99,94% for both the first and second sensors; and Proximity sensor LJ12A3-4-Z/BX with an accuracy value of 99,58% for the first sensor and 99,46% for the second sensor. DAQ is able to run controller signal processing, detect faults, and activate brake light signal according to FSAE rules.

Curving Motion Control of a Traction Rail Mover Using a Dual BLAC Motor Drive

This article presents an improved position control method of an overhang-type rail system considering a curved path. The designed system is driven by two BLAC (brushless ac) motors, and the moving position is controlled based on the signal from a simple Hall position sensor mounted on the motor without any absolute position sensors. The rail is composed of both linear and curved paths. For the linear rail, the two motors are controlled to rotate in the same speed. However, in a curved path, the two motors must have different moving distance according to the curvature. Generally, in order to determine the proper motion commands for both traction motors, the actual curvature state and position have to be detected by a potentiometer or an encoder equipped with linear position sensor, but this method significantly increases complexity and cost of the system. This article aims to solve this problem by using a low-cost semiconductor IMU (inertia measurement unit) to estimate the actual rail condition. The IMU will then estimate the heading angle variation to compensate the motion commands for the two BLAC motors without any additional external absolute sensors. As a result, a balanced and improved motion can be achieved for an arbitrary rail path. Practical experiments using an overhang-type rail traction system were performed to verify the effectiveness of the proposed control scheme. The results show the advanced control performance in both linear and curved path, and also a smooth transition between them both.

Linear position sensor using magnetically bistable microwire

A linear position sensor based on the unique functionality of the magnetically bistable glass-coated microwire is presented. Despite the magnetic nature of the sensor, it is possible to separate the external magnetic field's contribution, thus providing independence from parasitic external magnetic fields. With the presented unique approach, it is possible to transfer the linear position of the piston into the switching time and obtain high sensitivity down to 1 µm. • Linear position sensor with down to 1 µm sensitivity based on bistable magnetic microwire • Linear position measuring is temperature and external magnetic field independent • 0.19% measurement error within the temperature range 15 – 50°C

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.

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.

Distance Measurement Using mmWave Radar: Micron Accuracy at Medium Range

This work provides a proof-of-concept for a linear-position sensor using an ultrawideband (UWB) frequency-modulated continuous wave (FMCW) radar system operating at 126–182 GHz. It is the first work to show environmental compensated and calibration-free distance measurements with micron accuracy at medium range using millimeter-wave (mmWave) radar technology. We addressed hardware imperfections, parameter estimation, and the free-space path, i.e., refractive index and near-field effects. The proposed signal processing chain is robust to interference and of low computational cost. Experiments reveal a systematic error of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm 1~\mu \text{m}$ </tex-math></inline-formula> over 4.8 m (0.8–5.6 m), and a random error at a minimum of 30 nm, providing very high sensitivity.

Interaction dynamics modeling and adaptive impedance control of robotic exoskeleton for adolescent idiopathic scoliosis

Adolescent Idiopathic Scoliosis (AIS), an abnormal lateral curvature of the patient's spine with vertebral rotation, is one of the biggest problems in the orthopedic profession. Non-surgical treatments of AIS, including bracing, has the following limitations: i) sensor-less design and lack of closed-loop control on the motion and forces exerted on the torso result in no adaption to the skeletal changes during the treatment, ii) lack of interaction control may also make the brace inconvenient and insecure for the patient. In this paper, a novel robotic exoskeleton equipped with linear actuators, position, and force sensors is developed to control the motion and forces exerted on the torso. It consists of three Stewart-Gough Platforms (SGP). Robotic AIS rehabilitation is modeled by combining the dynamics formulation of each SGP with the mass-spring-damper model of the thoracic segment and utilizing the inverse dynamics problem to compute the required forces for moving the spine to the desired position. Numerical ADAMS and MATLAB simulations are used to verify the interaction dynamics formulation. In addition, impedance control is used to control the interaction instead of using position and force control separately. A Model Reference Adaptive Impedance Control (MRAIC) is also proposed to compensate for the negative effects of uncertainties existing in the interaction dynamics modeling and improve the interaction control. The performance of the MRAIC is verified and validated using numerical MATLAB simulations and real-time experiments in terms of position tracking and reference impedance model tracking.

Development of a new control rod drive mechanism design for the ISU AGN-201M reactor

The Aerojet General Nucleonics (AGN) model 201-Modified, known as the AGN-201M reactor, plays an essential role in the educational and research activities at Idaho State University (ISU). The ISU AGN-201M's original Control Rod Drive Mechanism (CRDM) has been in operation for more than fifty years with no large-scale redesigns. The CRDM is required to eject the fuel rods within one second during a SCRAM event (also known as a 'reactor trip') and adjust the control rods' insertion speed, and keeps the rod insertion sequence correct. The existing control rod drive mechanisms meet these criteria but experience a few concerns due to aging. Concerns include complex maintenance and costly repairs for old electromechanical components, rod position feedback errors, and the impediment of the plate during a SCRAM due to binding of the lead screws of the existing mechanism. During a binding event, the drive mechanism becomes locked, preventing the control rod's magnetic plate from moving in or out under the reactor's normal and emergency operating conditions. Although, the binding has no effect on the ability of the rod to exit the core during the SCRAM. To counteract the concerns and issues with the current CRDM, a new design has been proposed using newer components and a simplified design.The new design utilizes more advanced electric and mechanical components that are commercially available. The new CRDM system is divided into four main aspects: (1) control rod movement design (motor, lead screw, guide rods), (2) control rod ejection (springs, electromagnet), (3) control rod position and feedback (position transducer, microswitches), and (4) material selection and structural analysis. The new design aims to reduce the overall complexity and probability of failure to improve the reactor's overall reliability. With proper material selection and improved structural design, the new drives are lighter with little to no change in structural integrity. The new control rod drive mechanism eliminates binding scenarios by using a single lead screw and implementing additional guide rods. An advanced linear position sensor and microswitches replace the existing and aging synchro system for accurate rod position feedback resulting in better reactivity control. The new design meets the reactor's operational limits by having an average reactivity insertion of 0.065% Δk/k per second, which corresponds to a total control rod insertion time of 19.23 s, while the control rod's ejection time remains less than one second during a SCRAM event. The new design ensures the reactor's long-term viability for educational and research activities by increasing the reliability and safety of operation for years to come.

Measurement and modelling of a linear electromagnetic actuator driven camless valve train for spark ignition IC engines under full load condition

Camless engine valve train for gasoline engines particularly port injection engines offer major improvements over traditional system with fixed valve timing and lift, in terms of efficiency, maximum torque and power, and emissions. Electromagnetic driven valve actuators are very promising in this context, but there are significant control problems. The use of displacement sensor could add extra cost to the camless engine. In this work, a moving coil actuator driven valve train was designed and prototyped and a 1D single-cylinder internal combustion engine model was built to investigate the benefit of without throttle by adopting such camless valve train using Ricardo WAVE under full load operating conditions. A novel low-cost sensor named linear actuator position sensor (LAPS) based on flux linkage change on search coil was constructed in LabVIEW by using current, voltage and proximity sensors to detect the valve lift. The measurement of valve lift and current was reported to prove the feasibility of the camless valve train. The valve lift was used for the single-cylinder engine model and the simulation shows that the peak overall engine efficiency using camless valve train reaches 38.2% and the peak torque increases by 5 Nm compared conventional throttled engine under full load operating conditions. The LAPS model was validated by the experimental valve lift and the high accuracy indicates that the LAPS can be adopted for future development of camless valve train for spark ignition IC engines.

Контроль хода гидроцилиндров в гидравлических механизмах подъема установочных агрегатов

For the correct operation of hydraulic lifting mechanisms of the installation equipment of rocket and space complexes, it is necessary to ensure the synchronous movement of the rods of hydraulic power cylinders operating in parallel when performing working operations. Therefore, the urgent task is to develop synchronization systems that, along with ensuring the consistency of travel speeds, also provide the consistency of the mutual position of hydraulic cylinder rods. To solve this problem, we introduce a new approach which makes use of indirect methods for determining the working stroke of hydraulic power cylinders according to the results of measuring the angular or linear coordinates of the power elements of the mechanism. The first method is based on measuring the angular coordinates of the power elements of the lifting mechanism using angular displacement sensors - angular encoders. As for the second method, it relies on measuring the stroke of an additional link of variable length by means of magnetostrictive and cable linear position sensors. The paper briefly describes the device and the principle of operation of the sensors, and gives recommendations for the construction of measuring transducers as part of the lifting mechanism of the installation equipment. The new approach to solving the problem of controlling the stroke of hydraulic power cylinders in lifting mechanisms can be used in the development of advanced installation equipment for launch vehicles of heavy and superheavy classes.

Subdomain Model for Predicting the Performance of Linear Resolver Considering End Effect and Slotting Effect

Linear position sensors are essential parts of linear motion control systems. Among different linear sensors, linear resolvers are an appropriate choice for harsh environments. Design optimization of linear resolvers needs an accurate, but computationally fast model for their performance prediction. Slotting effect of the cores and end effect are two important phenomena that must be accurately involved in the model to ensure its reliable results. Therefore, in this paper a semi-analytical model based on subdomain modeling technique is proposed for linear resolvers. Then, according to the developed model, the induced voltages in the signal windings of the resolver are calculated and consequently, the position error of the resolver is determined. Numerical results are subsequently obtained by time stepping finite element method (TSFEM) to verify the proposed model. Finally, experimental tests on the prototype sensor are conducted to verify the success of the simulations.

Design of Linear Magnetic Position Sensor Used in Permanent Magnet Linear Machine With Consideration of Manufacturing Tolerances

This paper proposes the design of a linear magnetic position sensor (LMPS) to detect the mover position of the permanent magnet linear synchronous machines (PMLSMs). The working principle of the LMPS is based on the well-known Hall-Effect. The Hall-Effect-based design of LMPS is considered because it provides a low cost and relatively harsh environment susceptible alternative for the position detection for long track PMLSM system. The initial design was performed using 3D-finite element analysis and genetic algorithm-based deterministic optimization. Based on the initial model, four LMPS were manufactured and tested under the output constraint of peak flux density > 0.1T and total harmonic distortion < 3%. From the test results, it is concluded that the manufactured LMPS suffered significant deviation in output compared to the simulation model. These anomalies arise because of the manufacturing tolerances. To further improve the design and manufacturing process of the LMPS considering the effect of tolerance, a reliability-based robust design optimization (RBRDO) of the LMPS is proposed. The results of RBRDO confirms its usefulness for the design process of the LMPS in terms of undesired design non-compliance cost and great robustness without sacrificing the accuracy of the output signal.

Thermal Study of the Ironless Inductive Position Sensors Installed on the LHC Collimators

The safe operation of the European Organization for Nuclear Research Large Hadron Collider relies on a complex system for equipment protection. An essential part of machine protection is the collimation system since it is used to protect the equipment from beam losses. This is achieved by using two jaws to intercept the particles making up the beam halo. Since the jaws are in close proximity to the beam, they must be positioned with micrometer precision from it. An ironless inductive position sensor (I2PS) is a relatively new linear position sensor used to measure the distance of the jaws with respect to the beam. During the operation, it is noted that the position read by the I2PS could be affected by temperature variation causing position-reading errors. This paper presents an experimental study conducted on the I2PS to determine the relationship between the position read by this transducer and the ambient temperature. Furthermore, this paper aims at determining the impact of the temperature changes in the collimator body, on which the I2PS is installed, and the position read by the sensor. The results show that the uneven thermal distribution along the body of the sensor leads to high position readings error. These results also show that, depending on the moving coil position, the sensor behaves differently, and hence, it is very difficult to compensate for the effect. Finally, this paper presents the results of a possible modification tested on the same setup to reduce the thermal effects.

Experimental thermal characterisation of an ironless inductive position sensor

This article reports an experimental study performed on the ironless inductive position sensor to understand the relationship between changes in the surrounding temperature and position reading of the novel linear position sensor. The measured variation of the basic electrical components with temperature is presented and shows that the position drift of the sensor varies with the state of the sensor. The states include the moving coil position, and the frequency of operation. The results also reveal that the resistance and inductance changes happen in all the coils. Furthermore, the results show that when subjected to an even temperature change, the moving coil contributes to the highest change. In addition, uneven thermal distribution along the body of the sensor leads to high sensitivity from the sense coils. The results also indicate that the inductance change is small and leads to a small position change.

Didactic means in knowledge and practical skills shaping in the technical education processes

The article deals with the didactic and technical aspects of the information media selection and organization in educational processes in the field of operation and testing the electrical components and systems. The aim was to develop a presentation means that enable the acquisition of practical skills and understanding of the theoretical aspects of the issues under consideration. The practical part presents propositions of original stands for testing and presenting the functioning of rotational speed sensors as well as linear and angular position sensors, used in electrical and IT systems in industry and vehicles. The design, physical implementation and the possibilities of applications were described.

High-precision absolute linear position sensor based on a standard line measure

High-precision absolute linear position sensor based on a standard line measure

Electrical Metrological Characterization of Ironless Inductive Position Sensors With Long Cables

The ironless inductive position sensor (I2PS) is an air-cored, high-precision linear position sensor, which is designed to be immune from external magnetic fields and to work in radioactive environments. It can thus be used as a valid alternative to the linear variable differential transformer (LVDT), which unfortunately exhibits a position error in magnetic environments. These two sensors are used to determine the position of the European Organization for Nuclear Research Large Hadron Collider collimator’s jaws with respect to the particle beam. Because of radiation presence in CERN accelerators, the I2PS has been designed to have no on-board electronics, the raw signal has to be carried through long cable lengths, and this may lead to performance degradation. This paper focuses on the electrical metrological characterization of the I2PS with long cables. A set of experimental measurements are conducted to assess the I2PS’ sensitivity to cable capacitance change. To gain a better understanding, a comparison with a commercial off-the-shelf LVDT is presented where required. This paper also presents a novel spice simulation that models the I2PS sensor and its electronics. Furthermore, a novel countermeasure circuit is presented to rectify the effects of capacitance change.