光磁気記録を応用したロータリエンコーダの試作

Demands for high precision machine tools have been increased as technology advances. Such demands require higher position control to allow the machine tools to produce higher precision end products. To facilitate the position control, magnetic and optical encoders are been widely used in the machine tools. Due to its advantage in withstanding hard environment such as oil, grease and dust over an optical encoder, along with its wide applications in industrial position control, a magnetic encoder has become a desirable choice for machine tools. The objective of this study is to develop a polarity changeable magnetizer for manufacturing coding patterns in a rotary encoder which is used to monitor runout errors for rotating components in machine tools. As opposed to commonly used capacitive pulse magnetizer in which significant amount of energy is required for its electromagnets that potentially causes high energy hazard, in this study, a polarity changeable permanent magnet is proposed and investigated through parameter studies to overcome such issue with the aim placed on producing sufficient magnetization on a thin silicon steel plate to produce desirable coding patterns on the rotary encoders.

UV imprint fabrication of polymeric scales for optical rotary encoders

Optical encoders are mainly used in modern motion servo systems for high-resolution and reliable position and velocity feedback. Pseudorandom optical rotary encoders are single-track and use a serial pseudorandom binary code to measure absolute position. The realization and analysis of such a rotary encoder with advanced code scanning and error detection techniques, as well as an improved redundancy in operation, are presented. A presented serial code reading solution uses two phase-shifted code tracks and two optical encoder modules. So, the realized encoder, hybrid in nature, provides “output on demand” and more or less reliable position information using very efficient error checking. Compared to a standard absolute encoder, this encoder requires a smaller code disc, facilitates installation, has greater flexibility in operation, and is less sensitive to external influences.

Machine learning-based method for linearization and error compensation of a novel absolute rotary encoder

WITHDRAWN: Implementation dc motor as servomotor by using arduino and optical rotary encoder

Bit patterned media (BPM) is expected to enable the magnetic storage density in hard disk drives (HDDs) beyond 1 Tb/in2. BPM uses isolated magnetic islands to record the data information. However, the large volume fabrication of those patterned media disks at an affordable cost is a challenge for this new technology. A master template is the first step for patterned media fabrication. Using nano-imprint technology, the master template can be replicated to tens of thousands of pattern disks. A rotary electron beam lithography machine or plasmonic nanolithography machine is recommended to assist in the fabrication of the master template. In both systems, a high resolution encoder system for positioning in the rotary lithography machine is necessary. In this paper, a magnetic rotary encoder system is introduced. The encoder system can be operated at several thousand revolution per minute (RPM). The scale pitch is 90 nm which is one to two orders smaller than current optical encoders. The resolution is about 2.8 million counts per revolution (CPR). A flying magnetic head is used to retrieve the readback signal from the magnetic encoders. A field programmable gate array (FPGA) is implemented to finish the high speed signal processing and provide a digital format encoder signal to trigger the lithography machine at a rate of several Mega Hertz.

This study proposed a rapid prototyping fabrication method for micromotors that allowed us to develop both 1 mm and 1.5 mm diameter permanent-magnet synchronous motors (PMSMs) with an optical rotary encoder. First, an integrated electroforming method was proposed for combining stator housing and flexible print circuit (FPC) coils to ease the manufacturing and assembly of micromotor components. This is particularly useful in the production of prototypes or small volumes of units. Second, an optical encoder was used to detect the rotational angle by means of a reflective code disk, an optical fiber, and a photo-detector. The micromotor was built with a code disk and an optical fiber. The code disk was designed to match the optical fiber and was made by photolithography and sputtering. Both the 1 mm and 1.5 mm diameter motors successfully achieved a rotational speed over 20,000 RPM and due to a 50 µm diameter optical fiber core, the encoders showed a resolution of 12 and 18 pulses per revolution (PPR), respectively.

A new kind of the rotary encoder based on the magneto-optical (MO) storage is proposed. Using the MO methods, a small high-precision high-response rotary encoder can be realized. High precision is achieved by a two-stage process in which the code disk is firstly written using the direct transfer recording, and then rewritten using the corrections based on the measured errors. The systems for writing to, reading from, and evaluating the MO encoder are developed, with the optimal MO encoder reading and writing parameters determined experimentally. A trial MO encoder with a resolution of 9000 pulses/revolutions is created directly from a reference encoder, delivering an accuracy of approximately 2.8 in. The maximum resolution and response frequencies achieved are 18000 p/r and 400 kHz. After the corrected transfer recording, accuracies of 1.3 in at a resolution of 2250 p/r and 1.7 in at 9000 p/r are achieved.

Use of rotary optical encoder for firing detection in a spark ignition engine

The photoelectric rotary and angle encoder is a digital angle measuring device, which is integrated with optics, mechanics and electrics. Because of its simple structure, high resolution, and high accuracy, it has been widely used in precision measurement of angle, digital control and digital display system. With the needs of fast tracking and accurate orientation on the horizon and air targets, putting forward higher requirements on accuracy of angle measurement and resolution of photoelectric rotary and angle encoder. Influences of manufacturing, electronics segmentation, optical and mechanical structure and eccentric shaft to photoelectric encoder precision and reducing methods are introduced. Focusing on the eccentricity error, building up an error correction model to improve the resolution of angle encoder and the model was verified by test.

Several new types of absolute optical encoders of both rotary and linear function are discussed. The means for encoding are complete departures from conventional optical encoders and offer advantages of reliability, compact form, immunity to damage-induced dropouts of position information, and about an order of magnitude higher sensitivity over what is commercially available. Rotary versions have sensitivity from 0.02 arcseconds down to 0.003 arcsecond while linear models have demonstrated sensitivity of 10 nm (0.01 micrometers ) with higher sensitivities possible.

The study of thermal control in different geometry cavities (cylindrical and rectangular), to obtain high accuracy, short and long term stability responses applied to electronic instruments, is presented. Automatic dynamic electrical compensation is achieved by a feedback electronic circuit and low thermal inertia sensors. One sensor element is also employed as an actuator (heat generator) and the other as a reference sensor (resistance of manganine wire). In the rectangular cavity, the transducer (that is sensor and heater) is manufactured directly in the circuit board surface using a CAD/CAM equipment. This architecture allows a high dimensional accuracy of the sensor/actuator with a minimum track thickness, i.e., around 100 μm. In the cylindrical cavity, the transducer is manufactured using a copper wire. For this geometry, low aspect ratios were analyzed. Electronic response equations are derived and coupled to those governing the heat transfer phenomenon in cavities. After several tests, the model is compared to the experimental data. The obtained results seem to confirm the validity of the proposed idea, allowing an accurate temperature control in cavities with a self calibrating feature. At present time, we have obtained for both geometries a precision around of 0.01°C and an accuracy around of 0.1°C.

Development of a novel two-dimensional(2D) three-way(3W) fuel flow control servo valve with constant pressure difference

Nanosensors work on the "Nano" scale. "Nano" is a unit of measurement around 10- 9 m. A nanosensor is a device capable of carrying data and information about the behavior and characteristics of particles at the nanoscale level to the macroscopic level. Nanosensors can be used to detect chemical or mechanical information such as the presence of chemical species and nanoparticles or monitor physical parameters such as temperature on the nanoscale. Nanosensors are emerging as promising tools for applications in agriculture. They offer an enormous upgrade in selectivity, speed, and sensitivity compared to traditional chemical and biological methods. Nanosensors can be used for the determination of microbe and contaminants. With the advancement of science in the world and the advent of electronic equipment and the great changes that have taken place in recent decades, the need to build more accurate, smaller and more capable sensors was felt. Today, high-sensitivity sensors are used that are sensitive to small amounts of gas, heat, or radiation. Increasing the sensitivity, efficiency and accuracy of these sensors requires the discovery of new materials and tools. Nano sensors are nanometer-sized sensors that, due to their small size and nanometer size, have such high accuracy and responsiveness that they react even to the presence of several atoms of a gas. Nano sensors are inherently smaller and more sensitive than other sensors.

With the development of high spatial resolution satellites, such as IKONOS, we are able to make more use of spatial features to improve classification accuracy, especially for land-use mapping. In this paper, we compared the texture spectrum (TS) approach with 4 different schemes of gray level reduction, which are min-max linear compression (LC), gray level binning (BN), histogram equalization (HE) and piece-wise nonlinear compression (PC), on the panchromatic band of the sampled IKONOS CARTERRA imagery in terms of overall accuracy and kappa coefficient. The classification algorithm is on the basis of a frequency-based contextual approach that utilizes neighboring information within a particular window. The ranking of 5 different approaches is TS, PC, HE, BN and LC. TS achieves an overall classification accuracy of 72% at a window size of 53 while PC reaches an overall accuracy of 68% at a window size of 35 and LC reaches its highest accuracy of 65% at a window size of 29. TS approach needs a relatively larger window size to achieve higher classification accuracy while the other 4 gray level reduction approaches reach their higher accuracy at smaller window sizes. Within 9 land-use classes, a relatively large window size is more applicable to classify heterogeneous land-use types or areas having first order trend while smaller window sizes work better for more homogeneous land-use types or area with second order effect. The TS approach was found to be more capable of capturing first order trends while the other 4 approaches were more sensitive to local gray level variations thus better capturing the second order effect.