Rotary Encoder Research Articles

An effective, low-cost method to improve the movement velocity measurement of a smartphone app during the bench press exercise

Some studies have reported considerable errors in the movement velocity measurement when using the My Lift app. This study aimed to investigate whether these errors may be related to the use of a range of movement (ROM) statically measured prior to the movement (ROMMYLIFT) instead of ROM dynamically monitored. Ten young adults performed two repetitions of the bench press exercise on a Smith machine with loads that allowed two velocity conditions (above and below 0.6 m s−1). The exercises were monitored by the My Lift app, a magnet and a rotary encoder. After, 15 older adults performed the same exercise at different percentages of 1RM, monitored by the My Lift app and a magnet. The results revealed that ROM dynamically obtained by encoder (reference method) with the mean velocity above (0.497 ± 0.069 m) and below (0.450 ± 0.056 m) 0.6 m s−1 were quite different ( p < 0.05; large effect) from the ROMMYLIFT (0.385 ± 0.040 m). These errors provided highly biased and heteroscedastic mean velocity measurements (mean errors approximately 22%). The errors observed in adults were also observed in the older participants, except for loads equal to 85% of 1RM. The magnet method proved to be valid, presenting measurements very close to the encoder (mean errors approximately 1.7%; r > 0.99). In conclusion, the use of ROMMYLIFT is inadequate, as the higher the movement velocity, the higher the errors, both for young and older adults. Thus, to improve the measurement of the My Lift app, it is recommended that the magnet method be used in conjunction with the app to more accurately determine the ROM.

Improved Eccentricity Self-Detection Method Based on Least Square Algorithm for Polar Coordinate Encoder

Eccentricity error is the main error source of rotary encoder. In our previous work, a novel polar coordinate encoder has been presented for eccentricity self-detection and error compensation. In this paper, an improved eccentricity self-detection method based on least square algorithm is presented. We first establish the radial displacement equation in terms of rotary angle and eccentricity. Then, overdetermined equations can be constructed by taking sampling points into radial displacement equation, from which the optimal solution of eccentricity can be determined using least squares algorithm. Thus, angle compensation can be performed by submitting the calculated eccentricity into eccentricity error model. The proposed method offers a new strategy for automatic eccentricity self-detection and angle compensation of rotary encoder. Both simulation analysis and experimental test are performed to prove the effectiveness of the proposed method.

Assessment and Evaluation of Force–Velocity Variables in Flywheel Squats: Validity and Reliability of Force Plates, a Linear Encoder Sensor, and a Rotary Encoder Sensor

Research into flywheel (FW) resistance training and force–velocity–power (F–v–P) profiling has recently gained attention. Ground reaction force (GRF) and velocity (v) during FW squats can be predicted from shaft rotational data. Our study aimed to compare the inter-set reliability of GRF, v, and F–v–P relationship output variables calculated from force plates and linear encoder (presumed gold-standard) and rotary encoder data. Fifty participants performed two sets of FW squats at four inertias. Peak and mean concentric and eccentric GRF, v, and F–v–P outcomes from mean variables during the concentric phase of the squat were calculated. Good to excellent reliability was found for GRF and v (ICC > 0.85), regardless of the measure and the variable type. The F–v–P outcomes showed moderate to good reliability (ICC > 0.74). Inter-measure bias (p < 0.05) was found in the majority of GRF and v variables, as well as for all the calculated F–v–P outcomes (trivial to large TEs) with very large to perfect correlations for v (r 0.797–0.948), GRF (r 0.712–0.959), and, finally, F–v–P outcomes (ICC 0.737–0.943). Rotary encoder overestimated the force plates and linear encoder variables, and the differences were dependent on the level of inertia. Despite high reliability, FW device users should be aware of the discrepancy between the measures.

The MADE-Axis

Tangible controls-especially sliders and rotary knobs-have been explored in a wide range of interactive applications for desktop and immersive environments. Studies have shown that they support greater precision and provide proprioceptive benefits, such as support for eyes-free interaction. However, such controls tend to be expressly designed for specific applications. We draw inspiration from a bespoke controller for immersive data visualisation, but decompose this design into a simple, wireless, composable unit featuring two actuated sliders and a rotary encoder. Through these controller units, we explore the interaction opportunities around actuated sliders; supporting precise selection, infinite scrolling, adaptive data representations, and rich haptic feedback; all within a mode-less interaction space. We demonstrate the controllers' use for simple, ad hoc desktop interaction,before moving on to more complex, multi-dimensional interactions in VR and AR. We show that the flexibility and composability of these actuated controllers provides an emergent design space which covers the range of interactive dynamics for visual analysis. In a user study involving pairs performing collaborative visual analysis tasks in mixed-reality, our participants were able to easily compose rich visualisations, make insights and discuss their findings.

Interpretation of force profiles in mill-scale LC refining

Abstract A set of piezo electric force sensors is implemented in a 52-inch mill-scale low consistency refiner to explore the effect of varying operating conditions on bar force profiles. The sensor replaces a short length of a stator bar and measures normal and shear forces applied during the passage of each rotor bar. In previous work with this type of force sensor a rotary encoder was used to investigate force profiles for individual bar passing events (BPE) on a 16-inch laboratory-scale refiner. In the work presented here, force profiles for individual BPEs are identified based on key features in the time domain force data. The individual bar force profiles are classified as single peak events which feature one peak corresponding to the fiber compression force and as dual peak events corresponding to fiber compression force and the corner force. The bar passing events are then analysed based on their mean force profiles and their dual peak ratio in the bar passing event. Findings are compared and validated by previous work on bar force profiles. It is shown that dual peak events which are considered to represent the corner force, are present through out the whole range of refining and increase with increased refining energy. This increases the understanding of the way corner force contributes to the refining process. Furthermore, it is found that different radial positions on the stator plate are subjected to different force profiles. This is thought to be due to the difference in tangential speed and a change in the fiber and floc material properties at different radial positions.

Stirring System Design for Automatic Coffee Maker Using OMRON PLC and PID Control

The implementation of the use of PLC in this study was designed for a small scale in the process of stirring coffee drinks at a speed of 600 RPM. To get a stable speed so that the water does not overflow, a control system is needed. To get optimal results, a system design that can control the stirring speed is arranged automatically using a Programmable Logic Controller (PLC). This system is designed using a rotary encoder sensor C38S6G5-600B-G24N as a speed reader obtained from the movement of the motor, DC Motor JGA25-370 12V as an actuator or stirrer. PLC OMRON CP1E-NA20DR-A is used as a motor speed control device using the Proportional Integral Derivative (PID) algorithm to control the system according to the setpoint entered. The motor speed control system with the PID algorithm shows a system response that works well according to the researchers' expectations. The response of the system obtained is fast enough to achieve a stable speed with a small overshoot value. Thus this system was successfully designed to control the stirring process of coffee drinks automatically and produce stable stirring by giving a set point of 600 RPM at the parameter constant Proportional band is 720%; Integral time is 1.6s; and Derivative time is 0.2s with a rise time value is 1.3s; settling time is 11s; overshoot is 1.1%; and steady-state error is 0.5%.

Investigation of a dynamics-oriented engineering approach to ultraprecision machining of freeform surfaces and its implementation perspectives

In current precision and ultraprecision machining practice, the positioning and control of actuation systems, such as slideways and spindles, are heavily dependent on the use of linear or rotary encoders. However, positioning control is passive because of the lack of direct monitoring and control of the tool and workpiece positions in the dynamic machining process and also because it is assumed that the machining system is rigid and the cutting dynamics are stable. In ultraprecision machining of freeform surfaces using slow tool servo mode in particular, however, account must be taken of the machining dynamics and dynamic synchronization of the cutting tool and workpiece positioning. The important question also arises as to how ultraprecision machining systems can be designed and developed to work better in this application scenario. In this paper, an innovative dynamics-oriented engineering approach is presented for ultraprecision machining of freeform surfaces using slow tool servo mode. The approach is focused on seamless integration of multibody dynamics, cutting forces, and machining dynamics, while targeting the positioning and control of the tool–workpiece loop in the machining system. The positioning and motion control between the cutting tool and workpiece surface are further studied in the presence of interfacial interactions at the tool tip and workpiece surface. The interfacial cutting physics and dynamics are likely to be at the core of in-process monitoring applicable to ultraprecision machining systems. The approach is illustrated using a virtual machining system developed and supported with simulations and experimental trials. Furthermore, the paper provides further explorations and discussion on implementation perspectives of the approach, in combination with case studies, as well as discussing its fundamental and industrial implications.

Computer Interface for Real-Time Gait Biofeedback Using a Wearable Integrated Sensor System for Data Acquisition

Computer interfaces with visual biofeedback (BF) capabilities in robot-assisted gait training applications can help design subject-specific therapies, define tasks based on the patient's condition, and increase the training outcomes. This study presents the use of an open-source real-time computer interface as a subject-specific visual BF and monitoring tool during gait. The interface is used in combination with a low-cost Wearable integrated Sensor System for Data Acquisition (WiSSDA), which consists of a 3-D printed lower extremity exoskeleton equipped with rotary encoders and pressure-sensitive insoles that measure biometric data during the gait cycle. The system obtains the lower extremities’ joint kinematics in the sagittal plane and estimates the vertical component of the foot contact forces and the foot center of pressure. Experimental tests were performed to evaluate different gait parameters using the computer interface as visual BF to guide the subject with reference boundaries of kinematic and kinetic parameters as target trajectories. The results were used to evaluate the interface's performance for specific gait tasks. The results demonstrated the capabilities of the computer interface combined with WiSSDA for robot-assisted gait training applications using BF; providing an open-source, portable, and ambulatory device that can be used in outdoor environments. The proposed system can help bring gait rehabilitation outside the laboratory environment, eliminating the need for stationary equipment.

Analysis of Deformations and Von-Misses Stresses of the Main Shaft System in a Load Break Switch

Abstract This paper presents the study of deformations and Von-Misses stresses of the main shaft system during opening and closing operations of a rotary SF6 load break switch (LBS). The shaft consists of three axially connected parts made of steel where components are on ground potential and of plastic material, which is on high potential. The insulating shaft carries three rotating knife-blade contacts for the three phases. Static deformation of the insulating shaft is calculated by applying a defined torque between the two ends of the shaft. The results allow deducing the dynamic deformation. Maximum values of Von-Misses stresses are located at the geared connection between the plastic and the steel shaft. The rotation of the shaft system is measured synchronously by two optical rotary encoders in the front and rear sides of the LBS. The results confirm the twisting of the shaft system and provide its elastic deformation values. Travel curves obtained on both side of the LBS show different courses with respect to overtravel and rebound. Discrepancies can be explained by the deformation of the main shaft due to the acting forces, whereas manufacturing tolerances resulting in loose have a certain contribution.

Development of a real-time spalling measurement system for ball-type constant velocity joints

This study proposes a measurement system to detect spalling phenomena of ball-type constant velocity joints (CVJ). The spalling phenomena that usually occur in the inner race of a CVJ are a significant factor to the CVJ’s life, but it is very difficult to measure the spalling because the inner race is mechanically enclosed by an outer race and a cage. The developed system can not only detect the spalling but also measure the depth of adhesive wear in real time by implementing kinematics and applying force to an individual ball-type CVJ.The kinematics of a CVJ was analyzed to ensure that the measurement system operates the same as the actual CVJ. Especially, reciprocal yaw motions in the ball-type CVJ were perfectly implemented to the system. The system consists of three subsystems. The first system applies normal force to the contact points. Ball screws, spur gears attached to the motor amplify the force. The second system creates the reciprocal yaw motion with the same profiles as an actual CVJ. The third system is the measurement part, consisting of an incremental rotary encoder and a load cell. The resolution of wear depth is amplified and achieves up to 0.18°/μm.For validation, a ball-type CVJ was chosen and its spalling depth was measured. The results were verified by comparing the system measurement data with the profilometer measurement data.

AutoDock-IPS: An Automated Docking for Mobile Robot Based on Indoor Positioning System

Mobile robots are proven to be reliable in supporting the human tasks by using a computerized system that minimizes human errors. However, recharging the battery in these robots is still performed manually by the user. Therefore, to extend their lifetime, an indoor automatic docking system ‘AutoDock-IPS’ is created for mobile robot to charge its battery automatically. The automatic docking system determines the location of the docks (i.e., charging stations) so that, prototype can immediately navigate to them. Experiments were carried out to validate the docking method by utilizing a compass module as a direction sensor and a rotary encoder as a displacement indicator. These sensors are combined into a robust indoor positioning system. The results show that the prototype can find the fastest route to the docking station to perform battery charging procedure.

Calibration of rotary encoders with different interfaces by means of a dynamic goniometer

Rotary optical encoders are widely used in all areas of industry, robotics, and special equipment. The accurate measurement of their characteristics is a necessary task for their successful implementation. We attempt to find a unified approach to determining the accuracy of rotary encoders. The proposed approach is based on statistics and code reliability, which characterizes the probability that the measured code corresponds to the specified code. To determine the code reliability, one has to measure the turn angle with a goniometric device and compare the measured values with the encoder codes. The paper considers the dynamic goniometer for determining the error of absolute angle encoders, which allows for highly accurate measurements in a wide range of rotation rates. The measurement is made at certain moments of time, depending on the electrical interface of the encoder. In the case of a parallel interface, the time points are determined by the moment when the encoder code changes. This data collection allows for obtaining a general population. In the case of an encoder, with the sequential approach to reading the code, it is not possible to obtain the general population in a wide range of rotation rates. We analyze the above-mentioned case in detail and present experimental data obtained with a dynamic goniometer and the results of code reliability calculations.

A novel high resolution miniaturized capacitive rotary encoder

In this paper, design and prototyping of a novel, high resolution, and low-cost capacitive encoder were presented. Detailed analysis showed that the number of poles on the rotor should be as high as possible to keep the gain high and to reduce the non-linearity. Moreover, contrary to the common intuition, inter-electrode gap is found to have an optimum non-zero value, corresponding to a particular number of poles, in order to maximize the gain. However, increasing number of poles brings practical problems due to manufacturing limits and digital electronic frequency load. As the electronics, micro-controller based digital signal processing is used to keep the cost as low as possible. With miniaturizing the encoder geometry as a design target, the number of plates were increased to three to increase the capacitances. One prototype, which is around 3 cm in diameter could be successfully mounted to an industry oriented DC motor and tested. The tests of this miniaturized encoder showed non-linearity error of 0.12% and resolution of 0.02°. One source of the non-linearity error is the DC motor itself, and we believe that with a better setup, the error could be measured to be even better.

Arm Cycle Ergometer Electro-Mechanical System Design For Post-Stroke Medical Rehabilitation

This study was done to make the electro-mechanical arm ergometer cycle system used as post-stroke patient physiotherapy. The management system was expected to set the rotary frequency according to the therapeutic needs. To set the frequency of the rotation, the PID control with rotation sensor was used as feedback. The rotating sensor used consisted of the optocoupler and a rotary encoder. Based on the research that has been done, obtained constants of Kp = 0055, Ki and Kd = 2545 = 0.00005. Constants were selected because they were the most optimum constant trial and error method. The system is made to have a more significant percentage of error of 5%. In this study, the response time values obtained for each additional mass of the load at each frequency setting result are increased.

Improving the Angular Velocity Measured with a Low-Cost Magnetic Rotary Encoder Attached to a Brushed DC Motor by Compensating Magnet and Hall-Effect Sensor Misalignments.

This paper proposes a method to improve the angular velocity measured by a low-cost magnetic rotary encoder attached to a brushed direct current (DC) motor. The low-cost magnetic rotary encoder used in brushed DC motors use to have a small magnetic ring attached to the rotational axis and one or more fixed Hall-effect sensors next to the magnet. Then, the Hall-effect sensors provide digital pulses with a duration and frequency proportional to the angular rotational velocity of the shaft of the encoder. The drawback of this mass produced rotary encoder is that any structural misalignment between the rotating magnetic field and the Hall-effect sensors produces asymmetric pulses that reduces the precision of the estimation of the angular velocity. The hypothesis of this paper is that the information provided by this low-cost magnetic rotary encoder can be processed and improved in order to obtain an accurate and precise estimation of the angular rotational velocity. The methodology proposed has been validated in four compact motorizations obtaining a reduction in the ripple of the estimation of the angular rotational velocity of: 4.93%, 59.43%, 76.49%, and 86.75%. This improvement has the advantage that it does not add time delays and does not increases the overall cost of the rotary encoder. These results showed the real dimension of this structural misalignment problem and the great improvement in precision that can be achieved.

Design and Development of An Instrumented Knee Joint for Quantifying Ligament Displacements

Abstract Recently, robotic assistive leg exoskeletons have gained popularity because an increased number of people crave for powered devices to run faster and longer or carry heavier loads. However, these powered devices have the potential to impair knee ligaments. This work was aimed to develop an instrumented knee joint via rapid prototyping that measures the displacements of the four major knee ligaments—the anterior cruciate ligament (ACL), posterior crucial ligament (PCL), medial collateral ligament (MCL), and lateral collateral ligament (LCL)—to quantify the strain experienced by these ligaments. The knee model consists of a femur, lateral and medial menisci, and a tibia-fibula, which were printed from three dimensional (3D) imaging scans. Nonstretchable cords served as main fiber bundles of the ligaments with their desired stiffnesses provided by springs. The displacement of each cord was obtained via a rotary encoder mechanism, and the leg flexion angle was acquired via a closed-loop four-bar linkage of a diamond shape. The displacements were corroborated by published data, demonstrating the profiles of the displacement curves agreed with known results. The paper shows the feasibility of developing a subject-specific knee joint via rapid prototyping that is capable of quantifying the ligament strain via rapid prototyping.

Smart Medicine Reminder and Vending Machine

In this project a Smart Medicine Reminder and Vending Machine has been developed. Many old people have the tendency of missing the medicines or taking the medicines at wrong time. Often, they require someone to give them the medicines. Hence it is required to design a Medication Reminder Device that can help old people and many other patients to take medication on schedule. In situations like the CoVid-19 pandemic there is a physical contact between the patient and the caretakers, doctors. So, the devicedeveloped is capable of delivering medicine at prescribed time in which care-taker of the patient can store medicine in small boxes which will drop out according the time entered. Arduino IDE software platform and Arduino Mega along with RTC, servo motors, LCD, MP3 player, LED, Rotary Encoder with push button, IR sensor as hardware are used to build this project.

Crash Data Collection System

The increase in the number of fatalities in road accidents, it has become important to know the reasons for the crash and use the retrieved information for further study. The purpose of the project is to develop a crash box that can be installed for diagnosis into the vehicle. It will act as an independent system, which in case of a crash; will record speed, time of accident, and location of the vehicle, for some references. This recorded data will provide valuable information during the post-crash analysis. The device will make use of components like the ATMEGA328P, a GSM module, a rotary encoder, a NEO 6M GPS module & an EEPROM. The data obtained by the device can be used by the vehicle manufacturers to analyze the reason for the crash and to find proper solutions to prevent the same in the future.

Desain dan Implementasi Sistem Navigasi pada Automated Guided Vehicle (AGV)

This research aims to build mechanical system of Automated Guided Vehicle (AGV) and navigation system for AGV. The navigation system consists of RFID reader and rotary encoder. The testing result show that mechanical system of AGV was successfully finished. There is a mechanical problem on drive system of AGV. Each part of navigation system works well according to design. Line sensor can be used for path detection with the given threshold values. Encoder can be used to measure the speed of AGV with the maximum error accuracy less than 2 rpm. This result shows that every part of AGV is ready to run localization and navigation algorithm, even though, it needs to do some improvement on driving parts.

Development of a methodology of estimating limits of oscillations of optical system of photoelectric rotary encoders

The development of optical sensors with rotating mechanism requires estimation of oscillations limits. Although some work has been done on to linear encoders, there’s no information on such approaches related to rotary encoders. This manuscript proposes a computational approach of estimating oscillations limits of optical systems of rotary encoders. The approach is based on machine computations of waveforms modified by shifting position of one of discs, and rotates not around main axis of optical system. For estimations of oscillations during computations, one of optical discs translated against optical axis of optical system to perform occlusions, accounting differences in light distribution with oscillations presented. As the result of applying of methodology, computer program described and tested to calculate limits of hypothetical optical system, as well as its predictions were confirmed by comparison with behavior of real rotary encoder. This data was achieved with fewer computations, compared to classical calculation methods of light propagation. Developed methodology allows creating computer programs for estimating limits of oscillations within reasonable timeframe.