Tesi sul tema "Rotary encoder"

This thesis presents the design, implementation, and experimental testing of a rotary platform and its use for encoder calibration research. So far, the experimental results have demonstrated a calibration repeatability of better than 200 nano-radians (0.04 arc-second), which is much better than the state of the art precision angular encoder error of about 1 arc-second. The major contributions of this thesis include achieving ultra-accurate encoder calibration results as well as the design of an ultra-precise rotary table and a set of high-speed electronics. Others have developed many encoder calibration techniques. This thesis aims to identify, improve, and experimentally demonstrate the accuracy limit of an encoder self-calibration method developed at UBC. The work can be categorized into the following three parts: 1) Ultra Precise Rotary Platform Design, Manufacturing, and Assembly: A precision rotary platform was designed for encoder calibration and other spindle metrology research. The rotary platform uses a precision airbearing. Two different rotary encoders are included for rotation measurement. Three displacement probes monitor the motion of a target ball to identify and compensate for rotor vibrations. The platform is driven by an ultra-low cogging torque motor for minimum velocity ripple. The setup’s versatility makes it an excellent spindle metrology research tool. 2) High-Speed Electronics for Signal Processing: Fast processing is required for encoder calibration and precise stage control. Since no commercial controller met our fast signal detection and processing requirements, a set of electronics was designed: an FPGA-based high-speed digital controller (Avalanche) and a precision analog processing board (NanoRAD). Avalanche incorporates a fast-Virtex4 FPGA chip, a novel 1.2-GHz timer, five fast ADCs, four fast DACs, Gigabit Ethernet, High-Speed USB, and DDR RAM. NanoRAD incorporates fast comparators and precision buffers for analog processing and filtering. 3) Self-Calibration Algorithm Development and Experiments: After integration of the electronics with the mechanical assembly, the encoder calibration technique was examined. The method was adapted for the new setup, the damping estimation portion of the algorithm was improved, and the whole method was tested experimentally and in simulation. The encoder accuracy has been experimentally enhanced by 25-times from 5,000 (1 arc-second) to 200 (0.04 arc-second) nano-radians.

Machines, such as gantry robots, CNC or milling machines, must be able to perform consistently over time, and any degradation in performance due to changes in speed, age or mechanical failure must be detected or predicted as early as possible. Ultimately these changes lead to positioning errors and vibrations within the machine. To maintain accuracy the machines may checked 'on-site' or they may be 'mapped' in terms of desired and actual tool-tip position. These maps can then be integrated into the controlling software or hardware to improve performance. Monitoring the machines can form part of a feedback control loop. In order to carry out machine monitoring a number of devices are available. These include interferometers, ballbars, grid encoders and accelerometers for measuring vibration levels. None of these techniques forms a complete metrology solution. Some have limited coverage of the machine bed, others are too fragile to use on a working machine, and some do not provide the level of detail required to carry out a proper assessment of the machine. Initial investigations showed that vibrations are a key parameter to be monitored when making an accurate measurement of machine performance. Vibrations can reveal wear in components indicating imminent breakdown and they can themselves cause damage to the machine. Vibrations are commonly caused by rotating mechanical components. Patented in 1992, and developed within the Intelligent Machines Group, the Incremental Motion Encoder (IME) is a novel means of monitoring the motion of rotating shafts. The IME is a development of the angular encoder which uses 3 or more read heads. One read head allows the measurement of angular change. The use of multiple read heads allows it to detect lateral, as well as angular, changes in position. It is capable of measuring the submicrometre vibrations in rotating shafts over a wide bandwidth. By attaching an IME to the end effector of a machine it is possible to monitor the complete range of vibrations that occur at the end effector. A novel metrology technique, based on the attachment of the IME to the machine head, has been developed. This technique complements the measurement of vibrations with the remote monitoring of machine position. Laser triangulation is used to constantly track the position of the IME as it moves with the machine. The angles required to perform the triangulation are measured by using a laser that rotates with the IME. The laser beam strikes photosites at the periphery of the machine's range of motion allowing their angular position to be recorded by the rotating IME. The new technique has been developed and a test rig scanning unit has been constructed for evaluation. The test rig's construction allows for the measurement of angles against background torsion al vibrations. Lateral vibrations were prevented from occurring. Results from the test rig scanning unit indicate that the IME can be used for the measurement of angles of the order of 0.006 radians, which can then used for the triangulation of the scanner's position. Small changes in the position of the scanner (O.lmm) can also be detected making the technique suitable for the tracking of crude machine position. Further, investigations have involved the addition of an external torsional vibration source to the scanning unit and it has been shown that they distort the angular measurements. Algorithms based on filtering have been developed to use the IME data to compensate for such distortions. The algorithms have been evaluated using known angular changes and show a considerable reduction in the angular errors due to vibrations (a five-fold decrease in standard deviation from just under 0.0006 radians to 0.0001 radians).

This master’s thesis deals with calibration of incremental encoders. Introduces basic principles and terms in the field of rotary encoders and its calibration. The first part describes angular displacement sensors. Especially it focuses on optoelectrical incremental encoders. It also includes market research of very high-accuracy encoders. The second part contains description of precision calibration techniques with uncertainty to the thousandth of an arc-sec level. In the last part, the development of a calibration stage is presented and consequently the error map of an encoder is obtained.

Condition based monitoring is widely used for the determination of the health of machines. The Nottingham Trent University Computing Department has developed a new system, the Incremental Motion Encoder (!ME), which is based on the time interpolation of the digital signals produced by an optical encoder. Experiments have shown that the !ME can be used as a condition based maintenance sensor as it is possible to detect rolling element defects, an unbalanced shaft and oil contamination of a bearing. The system uses a geometrically configured optical device to scan a precision encoder disc and Digital Signal Processing technology is used to interpret the signals. Previous work has demonstrated the qualitative usefulness of the 1ME. However, further work was needed to assess the accuracy of the measurements, to analyse the principles of the 1ME, to validate the performance of the existing device and to develop methods for error definition and error compensation. Testing and experimentation on the existing experimental system have been carried out by the Candidate and an understanding gained of the device. The sources of error of the 1ME have been identified, which had not been quantified previously. Measuring and compensating for the three main sources of error, read head position, eccentricity of the encoder disc and encoder abnormalities are the three major tasks of the project. Modifications to the experimental rig have been developed in order to allow these tasks to be addressed. The Candidate has developed three different types of techniques to measure the position error of the read heads. A pattern recognition method was developed and is successful for 1ME systems that use an encoder disc with significant grating line errors. A second method using Fast Fourier Transform (FFT) has been developed to exploit the fact that the difference in the phase angles, obtained using a FFT, gives the angle between the read head positions. The new experimental system is now able to obtain the angular position of the read heads by using the index grating line. The third method relies on the presence of the index grating line on the encoder disc which may not be present in all systems. Eccentricity of disc centre relative to the centre of rotation affects the correct calculation of the angular position of the encoder disc. Algorithms have been developed by the Candidate in order to compensate for this type of error. Experimental results have shown that angular position error can be corrected successfully. The Candidate has developed methods for detection of small abnormalities of the encoder disc by using a multiple averaging technique. Computational algorithms have been developed to correct the encoder disc abnormalities by using individual information from each read head, promising results have been obtained from the experimental 1ME. An 1ME device can be tailored to fulfil the desired requirements of resolution, bandwidth and accuracy. A self calibration instrument can be developed by using the previously mentioned techniques in order to self calibrate and increase the accuracy and reliability of an IME's results.

This bachelor degree project was carried out at Saab AB Service and Repair, Arboga, Sweden. The objective was to design, construct and implement a new stable and reliable method of measuring the continuous vertical displacement (height) of the military search radar PS861 mounted on a hydraulic powered elevator. The end product needs to be durable enough to be fully operational in the harsh environment of an outdoor elevator shaft and yet as accurate and precise as possible since one of its purposes is to calibrate control equipment. Previously used technique has proven not to meet any of the above mentioned properties. A prototype using a high resolution quadrature output rotary encoder has been developed, allowing a completely digital interface. This new method has been evaluated in laboratory environment where tests have been conducted regarding both reliability and validity. The tests show that the new digital system provides highly improved accuracy and precision and in addition to that, the sensor with its IP-64 classification ensures operation even in the worst conditions. The technology developed in this project is also versatile and may be used in other situations where rotational motions are to be measured. Real life tests have not yet been carried out, but future test results will determine whether the product will replace the old system or not.

Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (page 25).
This thesis project aims to help complete the fabrication of a magnetic wheel encoder for a fleet of autonomous electric vehicles that will provide shuttle service across MIT's campus. Currently no self-driving vehicles exist for such a function, especially for mobility on a college campus. In an effort to assist the system's simultaneous localization and mapping (SLAM) algorithm, this magnetic wheel encoder was designed and implemented to more accurately and directly determine the vehicle's trajectory. After mounting the magnets and sensors, an algorithm was developed to map the vehicle's path given raw magnetic field data. Though the open-loop system was not a perfect map to the actual path taken, this work provides a guideline with more than enough accuracy for the SLAM algorithm.
by Alexander Prodromos Gilbert.
S.B.

A power assisted wheelchair combines human power, which is delivered by the arms through the pushrims, with electrical motors, which are powered by a battery. Today’s electric power assisted wheelchairs use force sensors to measure the torque exerted on the pushrims by the user. The force sensors in the pushrims are rather expensive and this approach also makes the wheels a little bit clumsy. The objective with this project is to find a new, better and cheaper solution that does not use expensive force sensors in the pushrims. The new power assisted wheelchair will instead only rely on its velocity, which is measured with rotational encoders, as feedback signal and thereby the project name “Torque Sensor Free Power Assisted Wheelchair”.

The project consisted of two main parts; an extensive construction part, where an ordinary joystick controlled motorized wheelchair has been rebuild to the new power assisted wheelchair without torque sensors and a development part, where different torque sensor free controllers has been designed, simulated, programmed and tested.

The project resulted in a torque sensor free power assisted wheelchair, where the final implemented design is a proportional derivative controller, which gives a very good assisting system that is robust and insensitive to measurement noise. The proportional derivative control design gives two adjustable parameters, which can be tuned to fit a certain user; one parameter is used to adjust the amplification of the user’s force and the other one is used to change the lasting time of the propulsion influence.

Since the new assisting control system only relies on the velocity, the torque sensor free power assisted wheelchair will besides giving the user assisting power also give an assistant, which pushes the wheelchair, additional power. This is a big advantage compared to the pushrim activated one, where this benefit for the assistant is not possible.

Presented thesis analyses a function of the particular type of the nanopositioner with aim to suggest and construct an electronic device suitable for control of the nanopositioner slider. In presented material there is a description of the control signals and possibility of their generating in the respect of slider movement accuracy. The main goal of the thesis is to describe electronic units ranging from power supply, control processor unit part to end part that directly joint nanopositioner. There is also programme equipment for microcontroller and computer, communication description, movement measuring and calibration and draft for the close-up of the control loop for additional increase of the movement accuracy.

At first this thesis is dealing with the basic principles of network analyzers and afterwards goes to propose conception of a polyscope, as a special type of the scalar network analyzer, designed for magnitude frequency response measurement of two-port devices. As a result of this part of the thesis is the polyscope's block circuit diagram and also selection of key integrated circuits for sweep generator, logarithmic detector and control circuits. As the following part of the thesis is a design of the all basic analyzer's circuits resulting in their schematics diagrams and printed circuit boards, do assembly of all modules and mechanical construction of the instrument and look of the front panel. Some of the tasks is implementation of the firmware and personal computer application able to download measured data from the circuit analyzer via USB and generate chart in Microsoft Office Excel book.

Incremental angle encoders are widely used in industry as a standard sensor to measure rotational axis angular position and velocity. The best commercially available angle encoders have achieved measurement accuracy on the order of 1 arc-sec with proper installation. Higher-accuracy encoders are needed to measure rotational axis angular position and velocity in ultra-precision rotary table based manufacturing and measurement applications. One specific application is to enable the development of maskless lithography technology used for mass manufacture of next generation semiconductors. In order to achieve accuracy well below 1 arc-sec, repeatable errors in the encoder measurement need to be removed through a calibration process. Numerous high-accuracy encoder calibration techniques have been developed, but the fundamental problem of calibrating angle encoders remains unsolved; their calibration results cannot be directly applied to the manufacturing machine. Existing calibration methods involve calibrating the encoder on a specially designed angle comparator, but the calibrated error is useless after transferring the encoder back to its application axis, due to the sensitivity of error on the installation. Other calibration methods capable of calibrating the encoder on its application axis cannot determine all the encoder error harmonics. There still does not exist a calibration method to quickly calibrate an angle encoder on its application axis, providing all encoder error harmonics. In this thesis the development of a Time-measurement Dynamic Reversal (TDR) encoder calibration technique is presented and its accuracy is validated, through simulation and experiment, and shown to improve encoder accuracy to the thousandth of an arc-sec level. The accuracy of this method is analyzed in detail, and an accuracy limitation based purely on measurement repeatability identified. Through experiments performed on a custom-built precision rotary table, experimental accuracy of several thousandths of an arc-sec is validated through uncertainty analysis and spindle radial error motion comparison. A comparison with the industry standard, the Equal Division Averaged (EDA) calibration method, shows agreement within 0.01 arc-sec for error harmonics not multiple of four. Due to the missing multiple of four harmonics, the EDA method is found to be 0.3 arc-sec less accurate than the TDR method in calibrating this experimental setup.

The thesis is focused on the development of a radioamateur short-wave transceiver. The basic functions, features and parameters are described in the introduction. The bandplan and appropriate types of emission are also included in the introductory part. The frequency synthesis module is discussed in the second part of the document. Emphasis is placed on the direct digital synthesis method (DDS) using modern Analog Devices circuits. The proposed DDS module includes a high-speed clock source. The description of an intermediate frequency module with a demodulator is also placed there. The final part in devoted to the design of a transceiver control panel with a graphical display, a keyboard and a rotary encoder. The firmware for an ATmega128 microcontroller is described in detail at the end of the thesis.

Den här rapporten beskriver arbetet med en automatiserad provrörsförflyttare. Det är ett examensarbete som har gjorts på företaget Q-linea AB. En karuselliknande konstruktion med en stegmotor användes för att flytta prover mellan ett antal positioner. En mikrokontroller som hanterar styrning och sensordata har programmerats i C. LabVIEW och en USB-kamera har använts som hjälp till att göra utvärderingar och tester av systemet. Målet var att konstruera en prototyp som uppfyllde de precisionskrav och tidskrav som ställdes, vilket också uppnåddes. Rapporten beskriver arbetsgången och avslutas med rekommendationer för fortsatt arbete. Rapporten innehåller en teoridel som kan användas till hjälp för att konstruera liknande system, d.v.s. roterande positioneringstillämpningar.

This thesis describes the work of an automated sample tube mover. This is a degree project and has been done at the company Q-linea AB. A carousel similar construction with a stepper motor has been designed for the task to move samples between a numbers of positions. A microcontroller has been programmed to control the movements and handle sensor data. LabVIEW have been used together with an USB-camera in order to do evaluations and tests of the system. The goal was to design a prototype that fulfills the demanded requirements of precision and timing, which also was achieved. The thesis describes the work process and concludes with recommendations for further work.

En aquesta memòria es presenten diversos treballs relacionats amb la utilització dels sensor de flux òptic de baix cost pel desenvolupament de nous sistemes de mesura compactes i de molt baix cost. Les aplicacions plantejades permeten aprofitar tot el potencial industrial d’aquest tipus de sensors. Els sensors de flux òptic tenen la peculiaritat d’incorporar dins d’un únic encapsulat un sistema d’adquisició d’imatges i un processador digital preprogramat per a realitzar el còmput de flux òptic (optical flow) de la imatge. D’aquesta manera, aquest tipus de sensors no requereixen cap sistema processador addicional i, en alguns casos, poden funcionar sense cap altre element addicional de control. Actualment, l’èxit dels sensors de flux òptic ha facilitat la seva producció industrial massiva amb costos de fabricació molt baixos el que ha incentivat el desenvolupament de noves aplicacions en camps tan diversos com la robòtica on el cost és un element fonamental en les aplicacions destinades a un mercat de consum. En aquesta memòria es presenta, per una banda, l’anàlisi de l’estat de l’art dels sensors de flux òptic i les seves aplicacions, i per l’altra, el treball de recerca realitzat sobre l’ús d’aquest sensor per a desenvolupar un codificador rotatiu incremental, un codificador absolut, un sistema de detecció de monedes falses de 2 euros, i per a realitzar el seguiment de la pupil•la de l’ull d’una persona amb discapacitat. Els resultats obtinguts a partir de les proves experimentals realitzades amb els diferents sensors de flux òptics utilitzats als dispositius proposats han permès validar les propostes realitzades i la versatilitat del disseny del sensor.
En esta memoria se presentan diversos trabajos de investigación relacionados con la utilización de sensores de flujo óptico de bajo coste para el desarrollo de nuevos sistemas de medida compactos y de muy bajo coste. Las aplicaciones planteadas permiten aprovechar todo el potencial industrial de este tipo de sensores. Los sensores de flujo óptico tienen la particularidad de incorporar dentro de un único encapsulado un sistema de adquisición de imágenes y un procesador digital preprogramado para realizar el cómputo de flujo óptico (optical flow) de la imagen. De esta manera, este tipo de sensores no requieren ningún sistema procesador adicional y, en algunos casos, pueden funcionar sin ningún otro elemento adicional de control. Actualmente, el éxito comercial de los sensores de flujo óptico ha facilitado su producción industrial masiva con costes de fabricación muy bajos lo que ha incentivado el desarrollo de nuevas aplicaciones en campos tan diversos como la robótica donde el coste es un elemento fundamental en las aplicaciones destinadas a un mercado de consumo. En esta memoria se presenta, por un lado, el análisis del estado del arte de los sensores de flujo óptico y sus aplicaciones, y por el otro, el trabajo de investigación realizado sobre la utilización del sensor para el desarrollo de un codificador rotativo incremental, un codificador absoluto, un sistema de detección de monedas falsas de 2 euros y para realizar el seguimiento de la pupila del ojo de una persona con el fin de desarrollar un dispositivo apuntador que pueda ser de utilidad para una persona con discapacidad. Los resultados obtenidos en las pruebas experimentales realizadas con los diferentes sensores de flujo óptico utilizados en los dispositivos propuestos han permitido validar las propuestas realizadas y la versatilidad del diseño del sensor.
This work presents the research performed with optical flow sensors and the proposal of several new compact and low cost applications developed to take full advantage of the industrial potential of these sensors. Optical flow sensors include into the same chip an image acquisition system and a digital signal processor programmed to compute the optical flow of the image acquired. These sensors do not require additional post-processing and can operate without any other additional external control or processing device. Currently, the commercial success of the optical flow sensors has fostered its massive industrial production and has reduced its final cost. This characteristic, combined with the versatility of the design of the sensor, has also fostered the development of a huge range of new applications in different areas, such as robotics, where the cost is a fundamental factor that prone the development and commercialization of new consumer applications. This works presents, in one hand, a review of the state of the art of the research and development related with optical flow sensors and, in the other hand, a set of new applications proposed to take full advantage of the characteristics of the sensor. The new applications proposed are: a relative encoder, an absolute encoder, a counterfeit system for the 2€ case, and an accessibility device that tracks the pupil of the user to control pointer displacement in a computer screen. This device has been designed specifically to help people with mobility impairments in the upper extremities that cannot use the computer mouse. In all cases, the experimental results achieved with the different optical flow sensors used in the new applications proposed have validated the utility and versatility of each proposal and the utility and versatility of the design of this optical sensor.

The aim of this diploma thesis is design of rotary-linear table with side clamping plate. Rotary-linear table is applicated to the profiled guideways used linear table. The work is focused on the design of the individuals nodes and their calculations.

Master’s thesis deals with design of laboratory supply with precise voltage and current measuring. At the beginning it presents properties, advantages and disadvantages of linear and switching supplies, based on these facts it chooses a linear type of regulator. The design continues with detailed description of power and control analog and digital circuits. The thesis includes description of taking control over the supply from the front panel or through computer. The last part is devoted to measurement results and to presentation of some static and dynamic parameters of the designed supply.

This thesis provides a standardized method to measure accuracy for engine and gearbox sensors. Accuracy is defined by ISO 5725, which states that trueness and precision need to be known to provide a metric for accuracy. However, obtaining and processing the data required for this is not straight forward. In this thesis, a method is presented that consists of two main parts: data acquisition and data analysis. The data acquisition part shows how to connect all of the equipment used and how to sample and store all the raw data from the sensors. The data analysis part shows how to process that raw data into statistical data, such as trueness, repeatability and reproducibility for the sensors. Once repeatability and reproducibility are known, the total precision can be determined. Accuracy can then be obtained by using information from trueness and precision. Besides, this thesis shows that measurement error can be separated into error caused by the sensors and error caused by the measurand. This is useful information, because it can be used to assess which type of error is the greatest, whether or not it can be compensated for, and if it is economically viable to compensate for such error.  The results are then shown, where it is possible to gain information about the sensors’ performance from various graphs. Between Hall and inductive sensors, there were no superior winner, since they both have their strengths and weaknesses. The thesis ends by making recommendations on how to compensate for some of the errors, and how to improve upon the method to make it more automatic in the future.

碩士
明道大學
光電暨能源工程學系碩士班
98
This work presents a high-precision optical rotary encoder with 2000 PPR resolution. The resolution of this system can reach 0.18°. The ordinary incremental rotary encoder system is unable to find the initiation values when the signal lost such as cutover. Then the initiation procedure of measurement must be repeat again. This experiment uses the MATLAB to design a set of zero position grating on the index-grating and the grating disk to produce the zero position signal. This study also presents the error analysis of a rotary encoder. The errors can be divided into three major parts: collimation effect, pulse width error and phase error. The cycle of the code wheel is 0.02mm, the gap between code wheel and index-grating must be less than 0.2 mm, and also the alignment between code wheel and index-grating must be less than .

碩士
明道大學
光電暨能源工程學系碩士班
100
Optical encoder is required in servo motor for accurate and speedy precision control. The traditional incremental encoder is easy to be operated. However, it has disadvantages of error accumulation and initial point loss. Therefore, it is gradually replaced by absolute encoder. The absolute encoder has advantages of high accuracy of absolute position, although the early development has disadvantages of coding complexity and coding area issues as coding pattern is increased. The coding technique is definitely an important factor for minimize the encoder volume. In this research, the M-code method is used, the code use one channel pattern as position information to avoid complexity. The code is finally adopted on 10 bits, 1024 absolute position optical ruler for verification. Also, A TOSHIBA TCD1208 linear CCD is used for signal detection. Keywords ：absolute encoder、M-Code、convolution、linear CCD

碩士
國立中央大學
光電科學研究所
96
This paper employs the radiometry and non-sequential ray tracing simulation to analyze the optical properties of optical rotary encoders. Use the numerical integration solution based on radiometry and the ray tracing simulation result to do curve fitting. Then we verify our numerical integration solution and ray tracing simulation result by the experiment result. By the RMSE (root mean square) analysis, the RMSE of experimental result and simulation result is 0.00171, and the RMSE of experimental result and numerical solution is 0.00168. We also optimize the sensitivity analysis of ORE, and we find that the effect of variance of width of the code fringe p is most significant. The effect of distance between the disc and the mask d is secondary. Finally, This paper present a novel absolute addressing method for ORE, and this method also can be employed to other kings of encoder.

碩士
國立清華大學
動力機械工程學系
106
The purpose of this study is to investigate the temperature effect on system errors of a rotary magnetic encoder, such as pole-pitch error, magnetic field error, assembly error and AMR elements detecting error. An accuracy analysis in various aspects, including thermal expansion in 1mm pole-pitch, distance expansion between AMR array, and magnetic field changes due to the physical characteristics of encoder material. In consideration with the above requirement, an environmental test platform was constructed to conduct experiments and to measure system errors in the range of 10 to 75℃. Experiments were planned to check assembly errors occurring in various temperatures and verify the correctness of the mathematical model. The results indicated that the concentricity of the rotary encoder and measuring gap were relatively sensitive to this system when temperature was not in a standard condition. Finally, a relationship was established between temperature and encoder precision. It also provides advices for how to reduce the system errors of a rotary magnetic encoder in industrial applications.

碩士
國立清華大學
動力機械工程學系
104
Magnetic rotary encoders are widely used for angular positioning and velocity feedback in high precision servo systems. Hence, the sensing accuracy, repeatability and resolution of the rotary encoder are of great importance. The aim of this research is to analyze several kinds of mechanical errors that influence the accuracy and repeatability of the magnetic rotary encoder. These are roundness and concentricity of the encoder and alignment error of sensor. In addition, a higher detecting gap of the sensor may also cause inferior repeatability of encoder signal. This paper provided a mathematical model to explain how the eccentricity, also known as an alignment error, affected accuracy. We proposed a method for calculating the eccentricity via measuring the radial run-out of the encoder. An experimental study was performed to verify the correctness of the proposed mathematical model. With eccentricity calibrated, the accuracy of the rotary encoders are greatly enhanced. Also, we summed up experimental results and established the relationship between errors and the performance of magnetic rotary encoder. After doing the system error analysis of the magnetic rotary encoder, this research also set up an auto-calibration system for eccentric error based on the concept of automated optical inspection. By integrating an industrial camera and optical lens, image processing program by IMAQ vision and automatic calibrating tool, we were capable of aligning to the magnetic rotary encoder precisely.

碩士
國立中興大學
土木工程學系所
106
The groundwater level is an important factor in the analysis of slope stability safety. It is very important for field monitoring techniques data and is one of the indicators of the disaster prevention early warning system. However, the groundwater level shaft are widely distributed, making it difficult for the surveyor to work.Due to the long-term use, some groundwater level shaft need to be cleaned and evaluated by the slug test to measure the permeability coefficient. In this study, the groundwater level measurement was automated, and two sets of instruments were produced using the Raspberry Pi with a rotary encoder. One is an automatic water level monitoring ; the other is an automatic groundwater level measurement. Due to the specification of the groundwater level shaft, the pulleys and pontoons used in the instrument are more limited in design. The pulley diameter is determined befor the indoor rate test. The results show that the diameter of the 4.8 cm pulley is more suitable for stability and accuracy. Then, two sets of instruments were made with this pulley, and the field monitoring and slug test were carried out using an automatic water level monitoring; the indoor water level measurement test was performed using an automatic groundwater level measuring instrument. The field monitoring and slug test data show that the automatic water level monitoring can accurately measure the groundwater level change and estimate the permeability coefficient of the groundwater level shaft, which will help to improve the inconvenience of the previous surveyor. Through the indoor water level measurement test, the results show that the error rate of the instrument within 50 meters is ±2.5%, and the accuracy is also expected. The water level measurement is successfully automated.

碩士
國立交通大學
電控工程研究所
103
With the development of industrial precision instrument technology, the applications of servo system are more and more widespread. This study focuses on the analysis and simulation of sinusoidal optical encoder, and uses the theory of radiation and optical simulation software to analyze the output of sinusoidal optical encoder. This article proposed a method to modify the error of the optical encoder and designed a scimitar-jagged mask according to the radiation theory. The experiments results are compared with the results of optical simulation software and the results of radiation theory by using RMSE (root mean square error) error to analysis the error. Comparing the results of radiation theory with the results of ASAP simulation, the RMSE based on parallel light source is 0.000558 which is similar to the RMSE based on Lambertian light source 0.049066. The theory of radiation in this study is proved effective and the optical model is accurate.

碩士
國立高雄應用科技大學
機械與精密工程研究所
101
The purpose of this thesis is to develop a micro permanent magnet synchronous motor with optical rotary encoder. The micro motor and its optical encoder are fabricated using MEMS technologies to reduce size. The light signal is transmitted through an optical fiber so the motor structure can be packaged easily. The rotating angle, speed and direction can be detected by asymmetric light source and incremental encoder disk. Two types of micro motors, 1 mm and 1.5 mm diameter, are made by a novel fabricating process combining coil windings and electroplated housing of the stator as one integrated part. The 1 mm diameter motor has length of 3.5 mm and output shaft diameter of 0.2mm. The motor can generate output torque 71.7 nNm and reaches maximum speed up to 20,000 RPM at input current of 0.3 A. This motor has surpassed the smallest commercially available motor of 1.5 mm from Namiki company. The feasibility of the innovative optical encoder is demonstrated using an asymmetric light source and incremental encoder disk at 6 mm diameter commercial motor. The 0.64 mm and 1mm diameter incremental encoders for two micro motors have resolution of 18 CPR and 12 CPR respectively. The optical encoders are successfully integrated and tested in the micro motors. Due to large rotating runout the optical encoders can only detect angle and speed currently.

碩士
南台科技大學
電子工程系
92
A servo motor coupled with a multi-turn absolute encoder (MAE) or an integrated rotary encoder (IRE) and its drive are generally sold together. The sale raises the product price and forms the closeness of the servo control systems. Sine the interface between the encoder and the drive is not opened. The thesis presents an interface design between an AC servo motor drive and an IRE to completely integrate the whole servo control system and reduce cost. A complex programmable logic device (CPLD) is employed to reduce the complexity of the corresponding interface where the communication protocols that include Manchester coding and the cyclic redundancy check (CRC) are analyzed, and removes the restriction of closeness. The experimental results which are measured by a digital scope are given to show the consistency between outputs from CPLD and those from the commercial product. In application using the origin of IRE simplifies the disadvantage of MAE which needs multiple data bus to just one serial signal output and then reduces the electrical complexity and the possibility of disconnection. This point has an important advantage in system combination and maintenance. IRE has combined serial high-resolution encoders to the design and implementation to increase its additional values. Finally the IRE increases the academic research for companies which want to advance in this direction to have design energy by themselves so that they don’t need to depend on foreign countries.