Rotary Encoder Research Articles

Wire Extensometer Based on Optical Encoder for Translational Landslide Measurement

A landslide is a natural disaster mostly accompanied by heavy rains, earthquakes, or volcanic eruptions. Due to its significant incurred losses, several studies have been conducted to develop a landslide monitoring system. In this report, we built and implemented optical-based wire-extensometers to measure and monitor a translational landslide in a prone area. This extensometer was built of an optical rotary encoder (whose shaft bonded to a spiral spring and sling rope) interfaced to a low-cost microcontroller as a principal component and subsequently linked to a GSM-based wireless network. The working principle of the employed sensor described in this paperwork is to count optical pulse signal and convert it into a length unit. This sensor can provide much better signal stability and show high resolution for a wide-range measurement than voltage- or current-based sensors. The specification of the engaged optical encoder provides 2000 pulses per rotation, leading to a length resolution of 0.011 ± 0.0083 mm with a speed limit of about 36 mm/s. Furthermore, the wire extensometer was examined in a remote place near a double-track train road to assess its performance in an actual field. A solar cell system was applied as its main power supply. An example of transmitted data shows a land shift from 12 mm to 150 mm, which is mainly triggered by high rainwater infiltration. This result demonstrates that the developed extensometer is deserved to be promoted for landslide monitoring in the geological research-work area.

Eccentric overload differences between loads and training variables on flywheel training.

There is considerable debate about the existence of a real eccentric overload in flywheel exercises. This study aimed to analyse the differences in concentric: eccentric mechanical output ratios between different loads and variables in the flywheel squat exercise. Twenty physically active men (22.9 ± 2.2 years, height: 1.8 ± 0.1 m, weight: 79.6 ± 8.2 kg) performed a loading test using five moments of inertia. Angular speed was measured using a rotary encoder, while the vertical force was measured using force plates. For each variable (angular speed, angular acceleration, power, vertical force, and torque), mean and peak values were calculated for concentric and eccentric phases to allow comparisons across the loads. We tested the possible differences in Load × Phase (concentric and eccentric) and Load × Variable. The level of significance was established as p < 0.05. A significant Load × Phase interaction was found in mean angular speed, peak vertical force, peak angular acceleration, peak power and peak torque. Higher eccentric overload values were observed with speed-derived variables (angular speed, angular acceleration and power). In conclusion, speed-derived peak variables and lower loads are more likely to show an eccentric overload and can be used to monitor responses to flywheel training.

A Kinematically Constrained Kalman Filter for Sensor Fusion in a Wearable Origami Robot

AbstractSensing for wearable robots is an ongoing challenge, especially given the recent trend of soft and compliant robots. Recently, a wearable origami exoshell has been designed to sense the user’s torso motion and provide mobility assistance. The materials of the exoshell contribute to a lightweight design with compliant joints, which are ideal characteristics for a wearable device. Common sensors are not ideal for the exoshell as they compromise these design characteristics. Rotary encoders are often rigid metal devices that add considerable weight and compromise the flexibility of the joints. Inertial measurement unit sensors are affected by environments with variable electromagnetic fields and therefore not ideal for wearable applications. Hall effect sensors and gyroscopes are utilized as alternative compatible sensors, which introduce their own set of challenges: noisy measurements and drift due to sensor bias. To mitigate this, we designed the Kinematically Constrained Kalman filter for sensor fusion of gyroscopes and Hall effect sensors, with the goal of estimating the human’s torso and robot joint angles. We augmented the states to consider bias related to the torso angle in order to compensate for drift. The forward kinematics of the robot is incorporated into the Kalman filter as state constraints to address the unobservability of the torso angle and its related bias. The proposed algorithm improved the estimation performance of the torso angle and its bias, compared to the individual sensors and the standard Kalman filter, as demonstrated through bench tests and experiments with a human user.

An Inexpensive Wiegand-Sensor-Based Rotary Encoder Without Rotating Magnets for Use in Electrical Drives

An Inexpensive Wiegand-Sensor-Based Rotary Encoder Without Rotating Magnets for Use in Electrical Drives

Prototyping of an indoor mobile mapping system

The paper deals with prototyping a kinematic measurement system for digitizing indoor environments of buildings. The scanning system itself consists of several sensors for localization (inertial measurement unit, rotary encoders and a stereo camera), while its main part is a Velodyne lidar. The procedure of data processing is performed by an algorithm for simultaneous localization and mapping (SLAM). The paper describes the hardware of the measurement system. Part of the contribution is the proposal of a series of tests evaluating the quality of the prototype of the mobile mapping system. The tests verify the accuracy of length measurement, the accuracy of the determination of the inclination of the measuring system, and the accuracy of the lidar position determination.

Absolute Two-Tracked Optical Rotary Encoders Based on Vernier Method

Driving synchronous machines requires early and accurate knowledge of the absolute position of the rotor; current solutions based on resolvers, sin–cos, or absolute encoders are complex, bulky, and costly. Hence, in this work two variants of absolute rotary encoder based on the Vernier method are analyzed. One, already discussed in the literature, displays the Vernier scale across the whole circumference (full-Vernier), and the other shows half Vernier traces over the entire perimeter (half-Vernier), which is an original feature. Both the implementations are characterized by only two tracks and as many sensors: the proposed conditioning algorithms provide the absolute angular position as a function of the time delays between the wave edges generated by the two traces, thus being of easy implementation on low-cost microcontroller units (MCUs). The Vernier encoders are also compared with the state-of-the-art absolute and relative solutions, i.e., incremental, binary, and Gray-code encoders. Experimental tests are carried out to assess the accuracy of the proposed sensors. The investigation shows that: 1) the full-Vernier cannot provide, in practice, a reliable estimate of the direction of rotation and of the actual angular sector without resorting to a third sensor; 2) the half-Vernier produces a trusty measurement of the absolute angle and velocity; and 3) can give a reliable position result with less than 30° shaft turn, but it can suffer from marginal performance degradation at low velocities in conjunction with high accelerations. Compared with the Gray encoder, the half-Vernier provides a simpler and more compact hardware for a given resolution, similar to that of an incremental encoder, at the expense of a small accuracy reduction at low speed.

Cavitation detection based on instantaneous angular speed

The study and detection of cavitation in hydraulic turbo-machinery has gained recently particular attention from both manufacturers and end users, due to the damage caused on machines’ surfaces that may result in costly sudden shutdowns. The traditional cavitation detection approaches exploit the noise and vibration signals that sense the vapor bubble implosion pressure waves, while advanced demodulation techniques are used in order to locate the resonances excited from these waves. This work aims to investigate an alternative methodology, where detection is achieved by processing the speed signal of rotary encoders. The motivation is that, contrary to microphones and accelerometers, the encoder is mounted directly on the shaft, where the rotor is connected and thus, is in direct contact with the cavitation waves. More specifically, in this study a centrifugal pump is tested under healthy and cavitating conditions, while an incremental encoder is rigidly installed on the pump’s shaft. The encoderâ–™s signal is processed in order to accurately estimate the raw speed signal. In addition, the order spectrum is used so as to extract the diagnostic indicators based on integer order amplitudes. From the results it can be concluded that particular components can give useful insights allowing the detection of both heavy and light intensity cavities.

Reduction of motion axis by sensitivity calibration of sensor in shape measurement instrument using normal vector tracing.

High-precision free-form surface mirrors are required for synchrotron radiation facilities in the scientific field and semiconductor lithography systems in the industrial field. Previously, we developed a nano-profiler with the goal of achieving a measurement accuracy of 30nm. The nano-profiler scanned and measured the slope angle of the surface to be measured with laser light and calculated the shape from the angle information. By driving the optical head and surface to be measured with four rotation axes and one translation axis, the surface could be scanned while keeping the optical path length constant. Although the rotation axis was controlled by a high-precision rotary encoder, pitching and yawing errors occurred in the translation axis. In this study, we attempt to eliminate the error of pitching and yawing from the conventional measurement operation of four axes of rotation and one axis of translation to the drive of only four axes of rotation. If the translation drive is eliminated, the optical path length will not be constant, and the sensitivity of the light-receiving element will change. Therefore, we propose a new method to calibrate the sensitivity of the receiving element and perform a comparative measurement with the conventional measurement method. Comparing the measured shapes obtained by both measurement results, it was found that the shapes had a maximum peak to valley difference of 6.2nm. Thus, the proposed novel measurement method allows a significant reduction in pitching and yawing errors.

Microcontroller-based Low-cost Seed Metering Module Retrofit on Cultivator

Planting is one of critical operations in agriculture. Ground wheel drives conventional metering mechanism, and results in improper placement of seeds because of skidding and vibration of the ground wheel. Electronically equipped seed metering system in the planter have potential to reduces losses associated with friction and wheel slippage. In this study, a retrofit type microcontroller based low-cost seed metering module was developed for commonly available cultivator. Basically, it can be called as mechatronics due to combination of both electronics and mechanical components. Seed metering plate’scell size was designed based on physical properties of black and green gram seeds. The microcontroller controlled motor's speed through Pulse Width Modulation (PWM) based on a signal obtained from a rotary encoder mounted on ground wheel. Under laboratory test, the developed module with a cell size of 5.5 mm found highest quality of feed index of 90 % for green gram and 86 % for black gram when operated at speed of 1.56 km/h. Average plant to plant distance was observed to be 6.73 cm, 6.55 cm for green and black gram during field evaluation. These observed spacing were close to desired spacing (6.28 cm) which intended in the precision metering mechanism. A unit's cost is approximately INR 2000. It facilitates sowing of pulse crop’s seeds without investing extra cost on purchasing separate planter required for it. This retrofit type proposed module will make cultivator as a precision planter suitable for sowing different crops at a very low cost.

Experimental Determination of Blade Tip Rub Forces in a Multiblade System

Abstract As improved efficiency goals require ever smaller gaps between rotating turbomachinery blade tips and stationary outer casings, it becomes more important to understand the physics of what happens when a blade tip rubs against the casing. A key piece of information to be determined is the force exerted on the blade tip during the rub event. This paper presents a method of extracting the blade tip rub forces from experiments conducted at The Ohio State University Gas Turbine Laboratory. To identify the forces during the rub, three multi-axis load cells are mounted behind a segment of the casing to measure the forces exerted on the casing during the rub event. Recovering blade tip forcing from this load cell data requires creating an appropriate model that can relate the measured data at the load cells to the high-speed rotating blade loads. The continuous, repeated nature of the rubs in the experiment makes this a challenge. This paper discusses the creation and performance of a state-space realization model developed from stationary ping test data that is used to address these challenges. The model is augmented with information on the angular position of the blades from a rotary encoder and information on the angular span of the rub, which increases with rub depth. Challenges and solutions related to finding tangential frequency responses, simultaneous blade rubs, and irregularities in the experimental data are also discussed. This paper aims to summarize the process and effectiveness of this approach for finding blade tip forces, as well as lessons learned along the way.

Real-Time Human Activity Recognition with IMU and Encoder Sensors in Wearable Exoskeleton Robot via Deep Learning Networks.

Wearable exoskeleton robots have become a promising technology for supporting human motions in multiple tasks. Activity recognition in real-time provides useful information to enhance the robot's control assistance for daily tasks. This work implements a real-time activity recognition system based on the activity signals of an inertial measurement unit (IMU) and a pair of rotary encoders integrated into the exoskeleton robot. Five deep learning models have been trained and evaluated for activity recognition. As a result, a subset of optimized deep learning models was transferred to an edge device for real-time evaluation in a continuous action environment using eight common human tasks: stand, bend, crouch, walk, sit-down, sit-up, and ascend and descend stairs. These eight robot wearer's activities are recognized with an average accuracy of 97.35% in real-time tests, with an inference time under 10 ms and an overall latency of 0.506 s per recognition using the selected edge device.

Monitoring River Sediment by Optimizing Arduino Capabilities Controlled by the PID Algorithm

Sediment causes serious water problems, including flooding, water pollution, and other issues related to water sediment. The data found that 82% of the 550 rivers in Indonesia were polluted and in critical condition. Hence, river maintenance is essential, especially for monitoring the existence of river sediment. This research makes a device to monitor sediment in the river and measure its volume. The device consists of a small boat in which an Arduino Mega 2560 RS microcontroller was an Arduino Mega 2560 RS microcontroller which will control sensors, motors, and a rotary encoder in monitoring and measuring sediment. This paper explained how Arduino could move the boat looking for sediment, detect sediment with infrared sensors, raise and lower the sensor by adjusting the motor in front and behind the boat and finally calculate the volume of sediment. The electronic circuits, block diagrams, and programs used are described in detail in this paper and discuss sensor accuracy and accuracy of measurement results. The result is the device can detect the sediment, measure the height of the sediment, trace the sediment to measure its length, and then rotate to measure the width of the sediment. All movements are carried out by utilizing the capabilities of Arduino. The PID algorithm can precisely determine the initial position of the sensors. It can detect sediment accurately. The measurement results show that the device can work well with a relatively small error.

In Situ Measured Tooth Flank Wear of Plastic Gears under Spectrum Loading

The wear behaviour of PBT-steel gear sets under temporarily changed load has been investigated using an in situ gear test rig developed at the LKT. The in situ test method is based on analysing the timing differences between the index pulses of rotary encoders on the input and output shaft of the test rig. The loading torque was varied between two levels and compared to the permanently applied equivalent average load in terms of the resulting tooth flank wear. Moreover, the number of load changes has been varied to analyse the influence of load changes on the gear wear. The results show that the applied load spectrum determines the resulting tooth flank wear even if the average applied load is the same. Moreover, it could be shown that the sequence of the applied load, i.e., the load history, plays an important role, since the applied load and the duration of the applied load within the run-in-stage disproportionately affect the wear behaviour over time.

Control system for a variable period undulator prototype

The magnetic structure of the proposed variable period undulator consists of cylindrical magnets. Each magnet can be rotated by a small stepper motor, in order to adjust the magnetic field and form an arbitrarily shaped magnetic field profile on-axis. Meanwhile, a short prototype exists, equipped with a scalable control system to drive a large amount of stepper motors. This paper describes details of the control system implementation, results of the tests on different rotary encoder concepts for a magnet positioning feedback, and first magnetic measurements of the variable period undulator prototype.

A novel anthropomorphic breathing phantom with a pneumatic MR-safe actuator for tissue deformation studies during MRI and radiotherapy

A novel MR-safe anthropomorphic torso phantom with an MR-conditional pneumatic respiration system and inflatable lungs for tissue deformation studies is proposed. The phantom consists of a pair of lungs made from sponges encased in flexible polyurethane. The lung phantom also contains a set of silicone tubes of various diameters to mimic the larger vasculature and airways of the lungs. The lungs are surrounded by a plastic ribcage and immersed in a gelatine hydrogel within a flexible polyurethane skin. A plastic pneumatic pump system was constructed to inflate and deflate the lungs. A fibre optic rotary encoder was constructed to determine the volume of displaced air in the lungs. The pneumatic pump and rotary encoder were constructed of plastic materials to allow placement within the bore of the MR scanner with minimal interaction with the magnetic field. Breath-gated scans and rapid imaging scans (2.5 s per image) were taken of the phantom in the stationary state and during inflation/deflation, and with Cartesian and BLADE k-space sampling. It was found that BLADE shows the least motion artifacts during breathing. This phantom and respiration system shows potential for quality assurance of MRI incorporating breathing corrections and for radiotherapy applications in tracking a moving target.

Intelligent Fault Detection in Hall-Effect Rotary Encoders for Industry 4.0 Applications

Sensors are the foundational components of any smart machine system and are invaluable in all modern technologies. Consequently, faults and errors in sensors can have a significant negative impact on the setup. Intelligent, lightweight, and accurate fault diagnosis and mitigation lie at the crux of modern industries. This study aimed to conceptualize a germane solution in the domain of fault detection, focusing on Hall-effect rotary encoders. Position monitoring through rotary encoders is essential to the safety and seamless functioning of industrial equipment such as lifts and hoists, and commercial systems such as automobiles. This work used multi-strategy learners to accurately diagnose quadrature and offset faults in Hall-effect rotary encoders. The obtained dataset was then run through a lightweight ensemble classifier to train a robust fault detection model. The complete mechanism was simulated through interconnected models simulated in a MATLAB Simulink™ environment. In real time, the developed fault detection algorithm was embedded in an FPGA controller and tested with a 1 kW PMSM drive system. The resulting system is computationally inexpensive and achieves an accuracy of 95.8%, making it a feasible solution for industrial implementation.

Low-Cost Prototype Multidiameter Measurement for Vertical Cylinder Tank

The vertical cylinder tank can serve as a measuring tool and as a storage device. When the vertical cylinder tank is used as a measuring instrument, it needs to be calibrated. In this process, measuring the diameter of the vertical cylinder tank is the most important step. The diameter of the tank is divided into several parts, the first part is referred to as a reference, where the results of the reference measurement will be used in the measurement of other parts. To conduct this measurement, a prototype consisting of two sensors, namely, laser distance and rotary encoder, is build. The prototype was tested using five variations in standard tube diameters measured using a steel ruler. The results of this test produce an average correction of +0.17 mm with an error of 0.59%. Furthermore, the prototype is used to measure the diameter of the vertical cylinder tank, which is compared with the certificate of the results of tank measurements using a theodolite. Testing the prototype with a vertical cylindrical tank produces a correction of +8.73 mm with an error of 0.03%. This error value is within the error limit according to the OIML International Recommendation of R-071 for vertical tanks.

EXPERIMENTAL IN HEAD TRACKING CONTROL OF A FOUR OMNI WHEELED MOBILE ROBOT SYSTEM

This article describes an experimental investigation into the head tracking and control of a four-wheeled Omni-Robot. This study described the control scheme of the omnidirectional mobile robot. Additionally, the kinematics of the mobile robot is presented., A mobile robot with four Omni wheels was also developed on real hardware to verify the controller architecture design. The robot system is modeled and then implemented with the Arduino Microcontroller. This robot has two rotary encoders for running on the x-axis and y-axis, respectively. The gyro sensor (MPU-6050) is placed in the robot's middle and tracks data obtained by yaw angle. MATLAB Simulink was used to find the PD controller based on manual adjustment. The control architecture was deployed to complete and run the experiment on the mobile robot to evaluate the outcomes. The experiment results show the robot's motion control improvement in various scenarios.

Towards Interpretable Camera and LiDAR Data Fusion for Autonomous Ground Vehicles Localisation.

Recent deep learning frameworks draw strong research interest in application of ego-motion estimation as they demonstrate a superior result compared to geometric approaches. However, due to the lack of multimodal datasets, most of these studies primarily focused on single-sensor-based estimation. To overcome this challenge, we collect a unique multimodal dataset named LboroAV2 using multiple sensors, including camera, light detecting and ranging (LiDAR), ultrasound, e-compass and rotary encoder. We also propose an end-to-end deep learning architecture for fusion of RGB images and LiDAR laser scan data for odometry application. The proposed method contains a convolutional encoder, a compressed representation and a recurrent neural network. Besides feature extraction and outlier rejection, the convolutional encoder produces a compressed representation, which is used to visualise the network’s learning process and to pass useful sequential information. The recurrent neural network uses this compressed sequential data to learn the relationship between consecutive time steps. We use the Loughborough autonomous vehicle (LboroAV2) and the Karlsruhe Institute of Technology and Toyota Institute (KITTI) Visual Odometry (VO) datasets to experiment and evaluate our results. In addition to visualising the network’s learning process, our approach provides superior results compared to other similar methods. The code for the proposed architecture is released in GitHub and accessible publicly.

Design and Experiment of Sweet Potato Up-Film Transplanting Device with a Boat-Bottom Posture

Aimed at solving the problem of the incidence of large film-breaking holes in the current sweet potato boat-bottom-shaped transplant, a boat-bottom-shaped up-film transplanting device was designed. Starting from the agronomic requirements of sweet potato up-film transplanting with a boat-bottom posture, an arc-shaped gripping mechanism was designed. In order to avoid further tearing and breaking the film hole during the movement of the clamping mechanism under the membrane, a transposition mechanism and a positioning cam were designed to jointly control the movement of the clamping mechanism. In order to ensure the stability of the transplanting plant spacing during the operation of the machine, a rotary encoder was used to collect the forward speed of the machine and adjust the speed of the power shaft in real time. Field experiments were carried out in order to verify the reliability and stability of the operation of the above-mentioned design mechanism. In the field test, the advance speed was used as the test factor, and the test indexes included three indexes of the seedlings after transplanting and three indexes of the film holes. The test results showed that the qualified rate of node depth in the middle of the seedling (QRNDMS) is between 95.67% and 86.79%, the qualified rate of root depth at the base of the seedlings (QRRDS) is between 94.00% and 90.11%, and the qualified rate of seedling length into the soil (QRSLS) is between 97.89% and 91.67%. The film hole spacing is between 240.33 mm and 245.32 mm, the film hole length is between 37.01 mm and 42.10 mm, and the film hole length variation rate is between 1.05% and 7.48%. This study can serve as a reference for up-film transplantation, particularly for boat-bottom-shaped up-film transplantation devices.