Angular Displacement Sensor Research Articles

High-resolution tunnel magneto-resistive (TMR) angular displacement sensor with enhanced subdivision interpolation technique

High-resolution tunnel magneto-resistive (TMR) angular displacement sensor with enhanced subdivision interpolation technique

Research on self-calibration method of electric field time-grating angular displacement sensor based on error function phase shift

Research on self-calibration method of electric field time-grating angular displacement sensor based on error function phase shift

Microwave angular displacement sensor with wideband matching and impedance transforming

AbstractThis work proposes a microwave angular displacement sensor with wideband matching based on a wideband impedance transformer. According to the design requirement of the microstrip impedance transformer (load‐to‐source impedance of 250‐to‐50 Ω, centre frequency of 2.40 GHz) with Chebyshev frequency response, the proposed angular displacement sensor is explored for the high bandwidth sensitivity of 11.18 MHz/degree.

Error compensation analysis of time-grid angular displacement sensor

The time-grid angular displacement sensor is an advanced angular displacement measurement device widely used in various precision instruments, industrial control systems, and robotics, with high accuracy, fast response, strong anti-interference ability, and long life. In this paper, the sensing mechanism of the embedded time-grid angular displacement sensor is used to analyze the compensation effects of Harmonic error compensation, HHT-ELM Error Compensation, PSO-BP neural network error compensation, and Multi-step compensation effects of Harmonic error compensation, HHT-ELM Error Compensation, PSO-BP neural network error compensation, and Multi-step calibration method are analyzed and compared to find that the Multi-step calibration method has the best compensation effect but the compensation system is complex and suitable for places with high accuracy requirements. compensation, HHT-ELM error compensation, and Harmonic error compensation. and as the compensation effect decreases the compensation method also tends to be simpler.

Analysis of Multimode Circular Cross-Shaped Resonator With Asymmetric Via and Its Application to Microwave Angular Displacement Sensor

In this letter, the multimode circular cross-shaped resonator (MMC-CSR) with asymmetric via is proposed and analyzed. The formulation of via placement on the resonator asymmetrical to the input and output ports is given and exploited compared with the conventional symmetric formulation. An equivalent implementation structure is thus developed for angular displacement sensing, which is attributed to a circular stub that is printed on the top layer and held by a circular rotatable plate, while the remainder is printed on the fixed bottom layer. Rotating the circular stub along the asymmetric via leads to the linear variation of the transmission zero with angular displacement leveraging rotational displacement sensing with higher sensitivity and dynamic range. A prototyped sensor centered at 2 GHz with a 310 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> dynamic range in a clockwise rotation and average sensitivity of 4.03 MHz/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> and 0.083 dB/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> has been experimentally characterized.

Parasitic time-grating angular displacement sensor for precision position measurement of turntable bearing

This paper proposes a parasitic time-grating angular displacement sensor for detecting the position of the turntable bearing. The sensor is mainly composed of probe, rotor, and supporting signal circuit. The probe consists of two separated measuring units on the left and right, and each measuring unit is composed of four sensing units with iron cores, excitation windings, and induction windings arranged according to specific rules. The rotor is made of sinusoidal isometric grooves based on the bearing end cover of the original turntable bearing. The signal processing circuit is used to filter, amplify, and compare the induction signal; meantime, it can generate the excitation signal. The high-frequency clock pulse signal is used as the measurement benchmark to realize the analysis of the position information of the induction signal. The structure and working principles of the sensor are presented in detail. Through the finite element method simulation, the feasibility of sensor scheme is verified, and the theoretical resolution of the prototype sensor is estimated to be about 1.33e−5. A sensor prototype is designed for testing, and the experimental results show that its accuracy can reach −0.003611° to 0.002583° in the range of [0°, 360°] after compensating the error point-by-point through the look-up table method.

RJVS: A novel, compact and integrated rotating joint with variable stiffness

A variable stiffness joint is a key element for structural deformation, which is widely used in morphing mechanisms including mechanical arms, folding wings, etc. By adjusting the stiffness of the joint according to the external environment and/or system instruction, the motion response of the mechanical system can be controlled and its security and stability can be guaranteed. However, to develop a variable stiffness joint with small size and large bearing capacity is still challenging. Also, an accurate mathematical model and control method to describe the variable stiffness joint is very important. In this paper, a novel, compact and integrated rotating joint with variable stiffness is developed, whose rotational stiffness and motion can be real-time controlled. A new configuration of a stiffness-adjusting module with superior mechanical properties is proposed by changing the arm length of cantilever leaf springs. Then a universal mechanical model of stiffness which adapts to a wide range of deformation is proposed. The status of the stiffness-adjusting module is changed by rope driven in order to minize the structure. Angular displacement sensors and torque sensors are integrated to observe the static and dynamic performance of the joint. According to the established rotational stiffness model, the stiffness of the joint is adjusted by reverse calculation of the motor’s rotating angle. A nonlinear Proportion-Integral-Derivative method based on a Genetic Algorithm is proposed for motion control. The experimental results show that the proposed joint, with large bearing capacity and a wide range of stiffness adjustment, has integration functions of driving and sensing, and can achieve a good motion control performance.

On the use of Kalman filters for high-order mode rejection in PZT-based microscanners

This work discusses and compares two strategies for closed-loop control of quasi-static silicon mirrors for raster-scanning applications, actuated by thin films of lead–zirconate–titanate and with embedded piezoresistive angular displacement sensors. A first feedback control approach, based on piezoresistive readout of the device angular displacement through an integrated sensor, shows limitations related to high-order resonant modes of the mechanical structure. To overcome this issue, a feedback control scheme based on the use of a Kalman filter to estimate the angular displacement and velocity of the scanner is presented, achieving a maximum positioning error of 0.14∘ (1.75% of a 8∘ full-scale angular displacement), and a mean error within (0.74% peak-to-peak) over 80% of the scanned trace.

Fully Integrated Line Array Angular Displacement Sensing Chip

The angular displacement sensor is a digital angular displacement measurement device that integrates optics, mechanics, and electronics. It has important applications in communication, servo control, aerospace, and other fields. Although conventional angular displacement sensors can achieve extremely high measurement accuracy and resolution, they cannot be integrated because complex signal processing circuitry is required at the photoelectric receiver, which limits their suitability for robotics and automotive applications. The design of a fully integrated line array angular displacement-sensing chip is presented for the first time using a combination of pseudo-random and incremental code channel designs. Based on the charge redistribution principle, a fully differential 12-bit, 1 MSPS sampling rate successive approximation analog-to-digital converter (SAR ADC) is designed for quantization and subdivision of the incremental code channel output signal. The design is verified with a 0.35 μm CMOS process and the area of the overall system is 3.5 × 1.8 mm2. The fully integrated design of the detector array and readout circuit is realized for the angular displacement sensing.

An Ultracompact Angular Displacement Sensor Based on the Talbot Effect of Optical Microgratings.

Here, we report an ultracompact angular displacement sensor based on the Talbot effect of optical microgratings. Periodic Talbot interference patterns were obtained behind an upper optical grating. By putting another grating within the Talbot region, the total transmission of the two-grating structure was found to be approximatively in a linear relationship with the relative pitch angle between the two gratings, which was explained by a transversal shift of the Talbot interference patterns. The influence of the grating parameters (e.g., the grating period, the number of grating lines and the gap between the two gratings) was also studied in both a simulation and an experiment, showing a tunable sensitivity and range by simply changing the grating parameters. A sensitivity of 0.19 mV/arcsec was experimentally obtained, leading to a relative sensitivity of 0.27%/arcsec within a linear range of ±396 arcsec with the 2 μm-period optical gratings. Benefitting from tunable properties and an ultracompact structure, we believe that the proposed sensor shows great potential in applications such as aviation, navigation, robotics and manufacturing engineering.

Model of field robot manipulators and sensor for measuring angular displacement of its rotating parts

This research aims to measure and control the angular change of rotation mechanisms of (energy-saving) robotic manipulators used in agriculture to develop digital farming, energy saving, and quality product harvesting. The novelty of this research is that different processes and images are placed in a special processor for processing, and this robot processes the image according to the size of the tomato plant and tomato and tries to harvest the crop. This study presents the electromagnetic angular displacement sensor and its technical characteristics. The existing electromagnetic angular displacement sensors have been thoroughly analyzed and compared with other types of sensors. The reason for the low sensitivity of the electromagnetic angular displacement sensor has been investigated, and some technical modification to the existing sensor has been made. The magnetic circuits of the electromagnetic sensors have been analyzed. A method is proposed for expanding the range of angular measurements up to 180 degrees and increasing the sensitivity of the electromagnetic sensor without compromising the measurement accuracy. This, in turn, allows high-precision control and measurement of rotating mechanisms of all types of mechatronic systems and agricultural robots.

Smart angular displacement sensor for agricultural field robot manipulators

This study presents the electromagnetic angular displacement sensor and its technical characteristics. The existing electromagnetic angular displacement sensors have been thoroughly analyzed and compared with other types of sensors. The reason for the low sensitivity of the electromagnetic angular displacement sensor has been investigated and some technical modification to the existing sensor has been made. The magnetic circuits of the electromagnetic sensors have been analyzed. A method is proposed for expanding the range of angular measurements up to 180 degrees and increasing the sensitivity of the electromagnetic sensor without compromising the measurement accuracy. This, in turn, allows high-precision control and measurement of rotating mechanisms of all types of mechatronic systems and agricultural robots.

Angular displacement sensor for gear position detection based on the tunneling magnetoresistance effect

In the fields of robotics, machine tools and spacecraft, measurement of the gear angular position lays the foundation for closed-loop positional feedback. In this article, an angular displacement sensor based on the tunneling magnetoresistance (TMR) effect is proposed for the precise measurement of angular displacement. The developed sensor mainly consists of a TMR element, a signal conditioning circuit, a permanent magnet and some necessary assembly components. The TMR element is composed of eight magnetic tunnel junctions, which are arranged according to the dual-full bridge structure with a spatial electric angle difference of π/2. Signals containing time information and space information are obtained after the sinusoidal and cosine voltages signals are respectively connected in two bridges. The signals are processed by a signal conditioning circuit, and then the angular displacement is measured by counting the clock pulses. The structure, working principles and signal conditioning method of the sensor are presented in detail. Moreover, a sensor prototype and a conditioning circuit are designed for actual experiments, according to the measured gear with a modulus of 1 and tooth number of 240. The prototype sensor has a theoretical resolution of 0.00001°. The experimental results show that the prototype sensor has a working stability of ±0.00023° within 1 h, and its measurement accuracy is −0.0008611° to 0.001361° in the measurement range from 0° to 360°. Therefore, the proposed sensor can be applied to the highly precise measurement of angular displacement.

A Novel Compensatory Motion Detection Method Using Multiple Signals and Machine Learning

Harmful compensatory motion will seriously influence the upper limb rehabilitation effect of stroke patients. Existing compensatory motion pattern detection methods, which are mainly based on accelerometers, inertial measurement units (IMUs), and vision, have problems such as high installation requirements, calibration difficulty, object occlusion, and complex operations. To solve these problems, by analyzing the principle of compensatory motion, this paper designs a trunk restraint belt, compensation motion mode detection system that is composed of a force sensor (F-S), angular displacement sensor (AD-S), and surface electromyography (sEMG). Fifteen healthy subjects without dyskinesia completed normal motion and simulated compensatory movement modes (trunk rotation, trunk forward tilt, and scapular elevation) based on the system. Machine learning (ML) methods are used to classify three compensated motion and normal motion (NM). Among them, the support vector machine (SVM) classifier shows good classification performance for trunk forward tilt (F1-score = 0.9256), shoulder blade elevation (F1-score = 0.9190), trunk rotation (F1-score = 0.8262) and normal motion (F1-score = 0.9758). This method is a new compensation detection method with obvious advantages: it is easy to wear, and without considering the problems of calibration and target occlusion, it can not only identify the patient motion mode but also limit the large range of compensatory motion.

An ultrahigh‐sensitivity microwave angular displacement sensor with a wide dynamic range

A microwave angular displacement sensor with dynamic range up to 180° and ultrahigh sensitivity is designed and fabricated. In the proposed sensor, a stator is designed for reference and a rotatable rotor is attached to it to implement real-time measurement of the rotation angle. As the rotor is attached to the stator, a CSRR-like resonant structure would be formed, with the resonant frequency linearly changing with the angular displacement. The measurement results show that the resonant frequency of the designed angular displacement sensor increases from 2.398 to 6.348 GHz linearly as the angle varies from 0° to 180°, with an excellent sensitivity of 21.94 MHz/° achieved.

Simulation and Experimental Research on Electrical Control Anti-backlash Based on a Novel Type of Variable Tooth Thickness Involute Gear Pair

This paper presents an electrical backlash control method based on a novel variable tooth thickness involute gear pair (VTTIGP) through acceleration judgment. First, the principle, characteristics and theoretical tooth surface equation of the novel type of variable tooth thickness involute gear (VTTIG) are proposed. Compared with the traditional variable tooth thickness gear (VTTG), each transverse of the novel type of VTTIG has the same tooth root circle and the addendum circle. Therefore, there will be no interference caused by the excessive axial relative movement distance between the gear pairs when eliminating the backlash. The theoretical calculation equation of no-load transmission error (TE) and time-varying backlash for a dual-eccentric novel type of VTTIGP are deduced. Second, using the theoretical backlash equation and the eccentricities and the initial phases obtained through the experimental TE curve obtained with angular displacement sensors and the developed TE equation, the continuous backlash curve of the gear pair is obtained. Based on the RecurDyn software and its Colink control module, the co-simulation model of the novel type of VTTIGP and its backlash control system is used to explore the electrical backlash control method through acceleration judgment in the case of time-varying backlash. Finally, using angular displacement sensors and linear actuators, the experimental study on the anti-backlash control with different reversed positions under different input speeds is carried out, demonstrating that this novel electrical anti-backlash control method is effective.

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

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 ± <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$64^{\prime \prime }$ </tex-math></inline-formula> ) 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 ± <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4.4^{\prime \prime }$ </tex-math></inline-formula> ) in the range of 0°–360°.

A novel inductive angular displacement sensor based on time-grating

The paper proposes a novel inductive angular displacement sensor to measure large-diameter hollow rotating mechanical components in large science facilities. The sensor design includes a stator, a rotor with two layers of windings. The stator is fabricated according to the dimension of the rotor, which is the large-diameter hollow rotary mechanical components. Based on the principle of electromagnetic induction, the theoretical model of the proposed sensor is acquired by mathematical equations in detail. The proposed sensor design ensures integration of the large-diameter hollow rotating mechanical components with the stator, and solves the problem that the sensors cannot be coaxially installed in the closed-loop control process of large mechanical rotating parts. The performance of the sensor is evaluated by tests of the prototype sensor fabricated by printed circuit board technology, which manifests the effectiveness of the proposed sensor. The results demonstrate the value of original dynamic relative error is ±97.6″ over 0°–360° range, and the measurement error mainly includes first-order and second-order harmonic components. Therefore, the original errors are reduced by optimizing the angular displacement algorithm of the sensor, optimized results demonstrate the final relative accuracy of the sensor is ±3.5″ over the 0°–360° measurement range.

A 22-bit image encoder with optoelectronic integrated chip

This study aims to design an optoelectronic integrated chip to read absolute code information. A detector array matching the code disk was designed to better realize high-speed low-light detection. For the pseudo-random code channel, the readout circuit adopted a linear array CMOS image sensor architecture, where each pixel corresponded to an independent readout unit, making the readout signal more advantageous in terms of both reading speed and noise. For the incremental code channel, the readout circuit followed a distributed arrangement design, and a two-stage pipelined amplifier architecture was adopted to eliminate the influence of even harmonics and ensure the quality of the read signal. Finally, a high-precision angular displacement sensor test platform based on an optical continuous closed-loop was built to test the encoder prototype equipped with the chip. The results show that an angular resolution of 22 bits and a subdivision accuracy of 5.64″ have been achieved.

Development of two-redundant multi-turn absolute encoder based on small modulus reducer

In order to meet the development needs of aerospace servo technology, the angular displacement sensor, which compact structure, high reliability, and be able to adapt to harsh working environments is used for the measurement and feedback of the high speed of the servo motor output shaft. The design of a two-redundant multi-turn absolute encoder based on a single-turn absolute encoder and a precision small modulus reducer, which realizes the high speed measurement of the servo motor shaft at 8000 rpm. Product performance meets the technical indicators of similar products of HEIDENHAIN encoders, can withstand high temperature, long working life, good dynamic performance, small space and light weight. System test and simulation analysis show that the design technical scheme is effective and feasible, can meet the requirements of the servo system.