Rotary Encoder Research Articles

An Encoding ASIC With Real‐Time Correction for Inductive Angular Sensing Systems

ABSTRACTThis article presents an application specific integrated circuit (ASIC) for inductive angular sensing systems, integrating analog‐to‐digital converters (ADCs), digital signal processing (DSP) circuits, and a RISC‐V core on‐chip. The chip, fabricated in a 0.11‐μm CMOS process, is capable of real‐time error correction and angle encoding in response to nonideal factors such as offset, nonlinearity, and noise in the system's sensing signals. This integrated encoding solution could effectively address the issues of large system volume, saving hardware resources while achieving high precision angular measurement. A rotary encoder was additionally developed, utilizing a compact printed circuit board (PCB), which integrates the proposed ASIC, sensing front‐end circuits, and inductive coils. When the on‐chip real‐time correction is enabled, the resolution of the encoder is improved from 0.3516° to 0.0054°, and the nonlinearity error in the 360° range is reduced from 0.5507° to 0.0320°. Besides, the nonlinear error has decreased by more than 90% at different rotation speeds.

Validity of Force and Power Measures from an Integrated Rotary Encoder in a HandyGym Portable Flywheel Exercise Device

Introduction: This study aimed to evaluate the validity of the HandyGym portable flywheel device with an integrated rotary encoder in measuring force and power during iso-inertial exercises compared to a traditional reference system. Methods: In total, 10 trained volunteers (3 women, 7 men; age 25.2 ± 3.8 years) performed half-squats with five different load configurations using the HandyGym device. Concurrent measurements were obtained from HandyGym’s rotary encoder and a criterion system (MuscleLab 6000 strain gauge and linear encoder). Five load configurations were tested, with 15 repetitions recorded per condition. The validity of the HandyGym measurements was assessed through mean bias, typical error of estimation (TEE), and Pearson correlation coefficients, with Bland–Altman plots used to analyze the agreement between the two systems. Results: The HandyGym showed high correlations with the reference system for both force (r = 0.76–0.90) and power (r = 0.60–0.94). However, systematic biases were observed, with the HandyGym consistently underestimating force and power at lower loads and overestimating power at higher loads. The TEE values indicated moderate to large errors, particularly in power measurements. Conclusion: The HandyGym provides valid force measurements with moderate bias, suitable for general monitoring. However, power measurements are less consistent, especially at higher loads, limiting the device’s utility for precise assessments. Adjustments or corrections may be necessary for accurate application in professional contexts.

PID PATH FOLLOWING CONTROL SYSTEM DESIGN ON UNMANNED AUTONOMOUS FORKLIFT PROTOTYPE

One of the technologies often used in material handling and material transport is forklift. Conventionally forklifts are operated by human operators. For efficiency, to improve security, safety, and occupational health and to minimize the risk of operators, forklifts can be automated. Therefore, the idea of unmanned autonomous forklift innovation was introduced. In this final project, a motion control system was designed for an unmanned autonomous forklift prototype both in simulation and hardware using PID control techniques, and the odometry system was equipped with a rotary encoder. In the simulation, the controlled variable was the distance and the manipulated variable was the force on the vehicle. Meanwhile, in the prototype, the controlled variable was distance and the manipulated variable was the motor pulse. In the simulation stage the PID control parameters were applied . with an error of 0.32% in the simulation. The PID control parameters were applied to the prototype, that is, . The distance tests were done with variation of 50 cm to 200 cm (25 cm intervals). One variation of the distance experiment was done 5 times. The average absolute error resulted was 2.36 cm.

Anterior Slope–Modifying Osteotomies Alter the Length Change Behavior of the Superficial Medial Collateral Ligament: A Biomechanical Study

Background: Increased tibial slope has been shown to lead to higher rates of anterior cruciate ligament graft failure. A slope-decreasing osteotomy can reduce in situ anterior cruciate ligament force and may mitigate this risk. However, how this procedure may affect the length change behavior of the medial ligamentous structures is unknown. Purpose/Hypothesis: The purpose of this study was to examine the effect of anterior slope–modifying osteotomies on the medial ligamentous structures. It was hypothesized that (1) decreasing the tibial slope would lead to shortening of the superficial medial collateral ligament (sMCL), (2) while the fibers of the posterior oblique ligament (POL) would be unaffected. Study Design: Descriptive laboratory study. Methods: Eight fresh-frozen cadaveric knee specimens underwent anatomic dissection to precisely identify the medial ligamentous structures. The knees were mounted in a custom-made kinematics rig with the quadriceps muscle and iliotibial tract loaded. An anterior slope–modifying osteotomy was performed and fixed using an external fixator, which allowed modification of the wedge height between −15 and +10 mm in 5-mm increments. Threads were mounted between pins positioned at the anterior, middle, and posterior parts of the tibial and femoral attachments of the sMCL and POL. For different tibial slope modifications, length changes between the tibiofemoral pin combinations were recorded using a rotary encoder as the knee was flexed between 0° and 120°. Results: All sMCL fiber regions shortened with slope reduction (P < .001) and lengthened with slope increase (P < .001), with the anterior sMCL fibers more affected than the posterior sMCL fibers. A 15-mm anterior closing-wedge high tibial osteotomy (ACWHTO) resulted in a 6.9% ± 3.0% decrease in the length of the anterior sMCL fibers compared with a 3.6% ± 2.3% decrease for the posterior sMCL fibers. A 10-mm anterior opening-wedge high tibial osteotomy (AOWHTO) increased anterior sMCL fiber length by 5.9% ± 2.3% and posterior sMCL fiber length by 1.6% ± 1.0%. The POL fibers were not significantly affected by a slope-modifying osteotomy. Conclusion: Tibial slope–modifying osteotomies changed the length change pattern of the sMCL such that an AOWHTO increased whereas an ACWHTO decreased the sMCL strain. This effect was most pronounced for the anterior fibers of the sMCL. The length change pattern of the POL remained unaffected by slope-modifying osteotomy. Clinical Relevance: Surgeons should be aware that anterior tibial slope–modifying osteotomies affect the biomechanics of the sMCL. After an extensive ACWHTO, patients may develop a medial or anteromedial instability, while an AOWHTO may overconstrain the medial compartment.

Separation of All Motion Errors in a Rotary Motor Using Dual Rotary Encoders

Separation of All Motion Errors in a Rotary Motor Using Dual Rotary Encoders

Jerk limited continuous tool path generation for flexible systems in non-cartesian coordinate systems

Inspired by computer numerical control (CNC) technology and drastic changes in the world of electronics and microcontrollers, the idea of using non-cartesian coordinate system for CNC machines became a topic of interest. Non-cartesian coordinate systems provide freedom of movement in systems with large working spaces where high dimensional accuracy is not a prime concern. Applications of such systems can be found in murals, where a painting is applied to a large wall of any arbitrary build material. In the present paper, a new design was introduced to automate the process of drawing murals on large surfaces. The proposed mechanism utilized chain and sprocket to overcome the size limitations of traditionally available x-y tables. In addition to that, the developed mechanism does not utilize the common robust structures used in the conventional CNC systems and the tool motion is created using flexible arms that are not heavily constrained. The effect of systems unwanted vibration has been eliminated using continuous trajectory and kinematic profiles. Parametric curve interpolation algorithms for trajectory planning were implemented to increase the flexibility of drawing complex curves. Parametric curves such as B-spline and non-uniform rational B-spline (NURBS) were employed to generate a jerk limited trajectory for motion control and extraction of kinematic profiles. Such trajectory constrains the jerk of the system and guarantees a smooth motion free of feed-rate fluctuations. Compared to other methods available for extracting the kinematic profiles, jerk limited method decreases the travel time and trajectory error. Ultimately, motion commands were produced by using kinematic profiles and the second order Taylor interpolator. STM32746ZG card was used as the main processor and two stepper motors controlled by a Bit Pattern interpolation algorithm were utilized to drive the proposed mechanism. The input pulses of stepper motors were stored as binary bits and transmitted to drivers in real-time. The feedback was also evaluated by two rotary encoders, placed at the end of the motors’ shafts. Encoder data were acquired and transmitted using a TCP/IP protocol to guarantee zero data loss during the transmission.

Acquired angle error correction based on variation of an angle detection signal intensity in rotary encoders

Abstract Rotary encoders are used in various machines to measure the angular position of a rotating axis. Therefore, rotary encoders are required not only to be highly accurate, but also usable in various environments. When using a rotary encoder on a machine, angle errors occur due to eccentricity between the encoder and the machine, the deformation of the scale, and the shaft runout of a rotation axis. Various methods have been adopted to reduce such angle errors. However, these methods have problems such as the large size and high cost of the rotary encoder, the necessity of additional devices for measuring, and increasing installation labor, so the environment in which they can be implemented is limited. In this study, we have proposed a method to correct the angle errors based on variation of an angle detection signal intensity in the sensor head. This method can correct the errors on machine without using multiple sensor heads or separate devices. The angle error estimated by this method is compared with that measured by the external equipment of a reference encoder. While the maximum angle error was 28.36” without correction, the residual error with correction can be reduced to 1.75” or less. From this result, the proposed method can improve the measurement accuracy of the rotary encoder already installed on the machine. Therefore, this method is an effective means for achieving both high rotational accuracy on machines and ease of correcting an error in rotary encoders to the machines.

Self-calibratable absolute modular rotary encoder: a theoretical feasibility study

Abstract This paper introduces a self-calibratable absolute modular rotary encoder based on the Equal Division Average (EDA) method, designed to significantly enhance measurement accuracy and simplify installation. The proposed design integrates multiple optical sensors into the encoder stator Printed Circuit Board (PCB), enabling precise absolute position measurement through the averaging of sensors data. This multi-sensor approach compensates for alignment and installation inaccuracies, which are common issues in conventional modular encoders. To validate the design and predict encoder behaviour prior to manufacturing, a theoretical modelling of virtual optical sensors is performed. Based on experimentally collected cross-calibration data from a real optical encoder, this modelling framework enables to estimate the efficiency of self-calibration algorithm with sufficient accuracy and optimize the design and performance of the encoder. The obtained results confirm that the proposed measurement system significantly reduces error margin, improving the reliability and precision of position feedback. The initial position deviation of several hundreds of arcseconds might be reduced and kept below 8 arcseconds by using two or more additional optical sensors, even with the 0.5 mm misalignment of the encoder stator.

Self-Calibratable Absolute Modular Rotary Encoder: Development and Experimental Research.

Advanced microfabrication technologies have revolutionized the field of reflective encoders by integrating all necessary optical components and electronics into a miniature single-chip solution. Contemporary semiconductor sensors could operate at wide tolerance ranges that make them ideal for integration into compact and lightweight modular encoder kit systems. However, in order to achieve the high accuracy of the operating encoder, precise mechanical installation is still needed. To overcome this issue and exploit the full potential of modern sensors, the self-calibratable absolute modular rotary encoder is developed. The equal division average (EDA) method by combining the angular position readings from multiple optical sensors is used to simplify the installation process and ensure the high accuracy of the system. The produced prototype encoder is experimentally tested vs. the reference encoder and the measurement deviations of using different numbers and arrangements of optical sensors are determined. The obtained results show encoder ability to handle the mounting errors and minimize the initial system deviation by more than 90%.

Design and Evaluation of an Open-Structure Rotary Magnetic Encoder for Subaqueous Environments

Design and Evaluation of an Open-Structure Rotary Magnetic Encoder for Subaqueous Environments

Dependability Assessment of a Dual-Axis Solar Tracking Prototype Using a Maintenance-Oriented Metric System

This study presents a numerical method for evaluating the maintainability of a dual-axis solar tracking system that can be deployed in residential areas for improved energy production. The purpose of this research manuscript is threefold. It targets the following objectives: (i) First, we present the construction of a self-sufficient dual-axis solar tracking system based on a low-power electronic schematic that requires only one motor driver to control the azimuth and elevation angles of the photovoltaic (PV) panel. The automated system’s main electronic equipment comprises 1 × Arduino Mega2560 microcontroller unit (MCU), 1 × TB6560 stepper driver module, 2 × stepper motors, 2 × relay modules, 1 × solar charge controller, 1 × accumulator, and 1 × voltage convertor. Additional hardware components such as photoresistors, mechanical limit switches, rotary encoders, voltage, and current sensors are also included to complete the automation cycle of the solar tracking system. (ii) Second, the Arduino Mega 2560 prototyping board is replaced by a custom-made and low-cost application-specific printed circuit board (ASPCB) based on the AVR controller. The MCU’s possible fault domain is then further defined by examining the risks of the poor manufacturing process, which can lead to stuck-at-0 (Sa0) and stuck-at-1 (Sa1) defects. Besides these issues, other challenges such as component modularity, installation accessibility, and hardware failures can affect the automated system’s serviceability. (iii) Third, we propose a novel set of maintenance-oriented metrics that combine the previously identified variables to provide a maintainability index (MI), which serves as a valuable tool for evaluating, optimizing, and maintaining complex systems such as solar tracking devices. The experimental data show that the computed MI improves the system’s maintainability and enhances repair operations, increasing uptime.

Design and Analysis of Receiver Coils with Multiple In-Series Windings for Inductive Eddy Current Angle Position Sensors Based on Coupling of Coils on Printed Circuit Boards.

We present a method for improving the amplitude and angular error of inductive position sensors, by advancing the design of receiver coil systems with multiple windings on two layers of a printed circuit board. Multiple phase-shifted windings are connected in series, resulting in an increased amplitude of the induced voltage while decreasing the angular error of the sensor. The amplitude increase for a specific number of windings can be predicted in closed form. Windings are placed electrically in series by means of a differential connection structure, without adversely affecting the signal quality while requiring a minimal amount of space in the layout. Further, we introduce a receiver coil centerline function which specifically enables dense, space-constrained designs. It allows for maximization of the number of possible coil windings while minimizing the impact on angular error. This compromise can be fine-tuned freely with a shape parameter. The application to a typical rotary encoder design for motor control applications with five periods is presented as an example and analyzed in detail by 3D finite-element simulation of 18 different variants, varying both the number of windings and the type of centerline functions. The best peak-to-peak angular error achieved in the examples is smaller than 0.1° electrically (0.02° mechanically, periodicity 5) under nominal tolerance conditions, in addition to an amplitude increase of more than 170% compared to a conventional design which exhibits more than twice the angular error. Amplitude gains of more than 270% are achieved at the expense of increased angular error.

Robotic Bartender Control Using DC and Servo Motor withThe Aid of Rectifier as Power Source

The studyfocuseson building a design and implement of robotic bartender with rectifier power source and embedded with volt-amp display to monitor supply voltage and load current. The usage of robotic bartender in the market make ease to the worker staff in food and beverage industries so that they can prepare drinks to customer in shortof time. For this paper, the design of robotic bartender is constructed using 3D printed components and use Arduino UNO as microcontroller to control input signal of rotary encoder and switches to commodore DC Motor rotation and servo motor deflection. The prototype of robotic bartender will be constructed, programmed with C language, tested with Proteus simulation software and hardware will be tested by using tachometer laboratory equipment for speed testing. Lastly the overall system is powered by rectifier with embedded volt-amp display for convenient use. Ironically the development of robotic bartender hardware is to fulfil two objectives which are to propose a new model of robotic bartender compatible with DC motor and servo motor and objective two to design and assemble rectifier circuit power supply with embedded volt-amp display meter to energize motor load

Multivariable Iterative Learning Control Design for Precision Control of Flexible Feed Drives.

Advancements in machining technology demand higher speeds and precision, necessitating improved control systems in equipment like CNC machine tools. Due to lead errors, structural vibrations, and thermal deformation, commercial CNC controllers commonly use rotary encoders in the motor side to close the position loop, aiming to prevent insufficient stability and premature wear and damage of components. This paper introduces a multivariable iterative learning control (MILC) method tailored for flexible feed drive systems, focusing on enhancing dynamic positioning accuracy. The MILC employs error data from both the motor and table sides, enhancing precision by injecting compensation commands into both the reference trajectory and control command through a norm-optimization process. This method effectively mitigates conflicts between feedback control (FBC) and traditional iterative learning control (ILC) in flexible structures, achieving smaller tracking errors in the table side. The performance and efficacy of the MILC system are experimentally validated on an industrial biaxial CNC machine tool, demonstrating its potential for precision control in modern machining equipment.

High‐Capacity Photochromic Rotary Encoder for Information Encryption and Storage

AbstractPhotochromic materials are widely used in optical data storage, data encryption, and anti‐counterfeiting because of their ability to be written, erased, and read repeatedly. However, conventional information encryption and storage capabilities based on a “matrix” pattern in a 2D plane are limited to fewer storage dimensions, making information less secure. Here, a new concept of expanding the storage dimensions is presented by manipulating the rotation angle in 2D photochromic encoding disks based on the principle of the absolute encoder. For this purpose, a novel photochromic material, NaNbO3:xEu3+ is developed, with highly efficient red emission, a large luminescence switching contrast, and antithermal quenching behavior. The designed photochromic rotary encoder made with the NaNbO3‐based material exhibits higher‐level data encryption than that of conventional encoders and unlimited storage capability. This study presents exciting opportunities for information storage and encryption using luminescent photochromic materials.

Development of undulator motion control system with redundant protections

The undulator is a key luminous component of the Shanghai high repetition rate x-ray free electron laser and extreme light facility, and the motion control system is an important part of the undulator. The main task of the motion control system is to complete the high precision adjustment of the gap and taper between the upper magnetic pole girder and lower magnetic pole girder, so as to adjust the wavelength of the radiation light. According to the development requirements of the motion control system for the U26 undulator, which is a conventional permanent magnet, this paper proposes a new motion control system with double position feedback closed-loop control, including programmable logic controller (PLC) closed-loop control based on position feedback by a linear absolute encoder (LAE) and driver closed-loop control based on position feedback by a rotary absolute encoder (RAE) of a servo motor. Multiple motion tests of the U26 undulator have shown that the repeatability accuracy of the gap is ±50 nm and the gap drive can reach 0.1 µm step size, the error of which is about ±20 nm according to the feedback of the LAE. The conclusion can be drawn that the motion step size and repeatability accuracy of the motion control system for the U26 undulator are improved by one order of magnitude on the basis of meeting all technical requirements. At the same time, motor torque protection, motor temperature protection, and redundant position protection with RAE can further improve the reliability and safety of the motion control system for the U26 undulator.

Direct threshing of paddy (Oryza sativa) ear-head with reduced straw and optimized grain throughput rate

Reduction of the straw intake is a new harvesting technique that reduces energy and input costs. In existing combine harvesters, the cutter bar of the standard header is set at an increased height, or the stripper header combine harvester is used to minimize the straw intake. The thresher was developed and tested in the year 2018 and 2019, at Indian Institute of Technology, Kharagpur, West Bengal to reduce the straw intake by direct ear head threshing of standing plants. It reduces energy consumption compared to some common existing harvesting methods. The specially designed plant guiding plates were accommodated before the threshing cylinder to achieve this. The set of two guiding plates passes over the plant’s row and converges the panicle portion of plants by bending them gradually. The rice (Oryza sativa L.) panicles were placed over the rotating cylinder and the stem portion remains in a standing posture. Thus, only 4.16% of total straw available on the plants was fed, and about 23 times straw intake was reduced. RSM-based response surface methodology was used to design the experiment. During the experiment, the grain throughput rate (GTR) was varied by changing the speed of plant feeding. To measure the cylinder speed, threshing torque, and plant feed speed the laboratory model thresher was equipped with rotary encoder, torque transducer and proximity sensors, respectively. The collected threshed mixture was analyzed to determine threshing performance. The optimized GTR and cylinder speed were 180 kg/h and 17.55 m/sec at which the threshing efficiency, total grain loss, and specific energy were 98.36%, 4.67%, and 1.1 kWh/t of grain, respectively.

Development and flight-test verification of two-dimensional rotational low-airspeed sensor for small helicopters

This paper describes the development and the verification of flight test results of a differential pressure-based, two-dimensional low-airspeed sensor designed for the navigation or disturbance detection in small helicopters. The compact and lightweight sensor is integrated with the main rotor of a small helicopter and comprises two probes at both arm ends, a differential pressure sensor, rotary encoder with one magnet and two sensors, microcomputer, a wireless data link, and battery. It measures the differential pressure between the total pressures captured by two total-pressure probes at each rotor angle, instead of using static pressure probes. Thus, the airspeed of the fuselage can be evaluated from the low speed. Flight tests were conducted employing a reference ultrasonic two-dimensional airspeed sensor for comparison. The results demonstrated that the magnitude error of the airspeed is less than 2 m/s for low-airspeed flights (<∼\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$<\\sim$$\\end{document}23 m/s) when utilizing Pitot-type probes. The error in wind angle approximated 30∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^\\circ$$\\end{document}, and the delay was less than or equal to that observed with a global navigation satellite system sensor.

Isometry of anteromedial reconstructions mimicking the deep medial collateral ligament depends on the femoral insertion.

This study aimed to investigate the length change patterns of the native deep medial collateral ligament (dMCL) and potential anteromedial reconstructions (AMs) that might be added to a reconstruction of the superficial MCL (sMCL)to better understand the control of anteromedial rotatory instability (AMRI). Insertion points of the dMCL and potential AM reconstructions were marked with pins (tibial) and eyelets (femoral) in 11 cadaveric knee specimens. Length changes between the pins and eyelets were then tested using threads in a validated kinematics rig with muscle loading of the quadriceps and iliotibial tract. Between 0° and 100° knee flexion, length change pattern of the anterior, middle and posterior part of the dMCL and simulated AM reconstructions were analysed using a rotary encoder. Isometry was tested using the total strain range (TSR). The tibiofemoral distance of the anterior dMCL part lengthened with flexion (+12.7% at 100°), whereas the posterior part slackened with flexion (-12.9% at 100°). The middle part behaved almost isometrically (maximum length: +2.8% at 100°). Depending on the femoral position within the sMCL footprint, AM reconstructions resulted in an increase in length as the knee flexed when a more centred position was used, irrespective of the tibial attachment position. Femoral positioning in the posterior aspect of the sMCL footprint exhibited <4% length change and was slightly less tight in flexion (min TSR = 3.6 ± 1.5%), irrespective of the tibial attachment position. The length change behaviour of potential AM reconstructions in a functionally intact knee is mainly influenced by the position of the femoral attachment, with different tibial attachments having a minimal effect on length change. Surgeons performing AM reconstructions to control AMRI would be advised to choose a femoral graft position in the posterior part of the native sMCL attachment to optimise graft length change behaviour. Given the high frequency of MCL injuries, sufficient restoration of AMRI is essential in isolated and combined ligamentous knee injuries. There is no level of evidence as thisstudy was an experimental laboratory study.

An optical-based measurement method for center distance between two double-hole components

PurposeIn the context of fixed-wing aircraft wing assembly, there is a need for a rapid and precise measurement technique to determine the center distance between two double-hole components. This paper aims to propose an optical-based spatial point distance measurement technique using the spatial triangulation method. The purpose of this paper is to design a specialized measurement system, specifically a spherically mounted retroreflector nest (SMR nest), equipped with two laser displacement sensors and a rotary encoder as the core to achieve accurate distance measurements between the double holes.Design/methodology/approachTo develop an efficient and accurate measurement system, the paper uses a combination of laser displacement sensors and a rotary encoder within the SMR nest. The system is designed, implemented and tested to meet the requirements of precise distance measurement. Software and hardware components have been developed and integrated for validation.FindingsThe optical-based distance measurement system achieves high precision at 0.04 mm and repeatability at 0.02 mm within a range of 412.084 mm to 1,590.591 mm. These results validate its suitability for efficient assembly processes, eliminating repetitive errors in aircraft wing assembly.Originality/valueThis paper proposes an optical-based spatial point distance measurement technique, as well as a unique design of a SMR nest and the introduction of two novel calibration techniques, all of which are validated by the developed software and hardware platform.