Quadrature Encoder Research Articles

Designing, Fabrication and Controlling Of Multipurpose3-DOF Robotic Arm

In the present work, we have successfully designed and developed a 3-DOF articulated Robotic Arm capable of performing typical industrial tasks such as painting or spraying, assembling and handling automobiles parts and etc., in resemblance to a human arm. The mechanical assembly is designed on SOLIDWORKS and aluminum grade 6061 -T6 is used for its fabrication in order to reduce the structure weight. We have applied inverse kinematics to determine the joint angles, equations are fed into an efficient microcontroller ATMEGA16 which performs all the calculations to determine the joint angles on the basis of given coordinates to actuate the joints through motorized control. Good accuracy was obtained with quadrature optical encoders installed in each joint to achieve the desired position and a LabVIEW based GUI is designed to provide human machine interface.

Performance of Two Space-Time-Frequency the Coding Schemes in Frequency Selective Channel

Discussion of two classic space-time-frequency coding (STFC) scheme in frequency selective channel transmission problems is given. One utilized the data order inversion and conjugation transform, which makes the quadrature data encoder can no longer be interpreted as orthogonality of channel parameter matrix. Another has data orthogonal pre-processing, which makes each symbol spreading stream uniformly to all sub-channels. The computer simulation results illustrate the theoretical analysis of the paper.

Design of Monitoring System for Linear Switched Reluctance Motor with Quadrature Encoder and Current Sensors

Design of Monitoring System for Linear Switched Reluctance Motor with Quadrature Encoder and Current Sensors

Enhancements to the JET poloidally scanning vacuum ultraviolet/visible spectrometers

Enhancements to the JET poloidally scanning spectrometers are presented, which will aid the exploitation of the recently installed ITER-like wall in JET. They include the installation of visible filter∕photomultiplier tube assemblies and spectrometers and the replacement of large rotating mirrors in the JET vacuum with small oscillating mirrors outside. The upgrade has resulted in a more robust and reliable diagnostic than before, which is described. Drifts in the mirror angle reconstructed from quadrature encoder signals are found, a reference signal being required. The use of the small scanning mirrors necessitated the inclusion of focusing mirrors to maintain throughput into the vacuum ultraviolet spectrometers. The mirror design has taken account of the extreme sensitivity of the focusing to the grazing angle of incidence, an aspect of importance in the design of grazing incidence focusing components on future machines, such as ITER. The visible system has been absolutely calibrated using an in-vessel light source.

A New State Estimator of PMSM Using Adaptive Extended Kalman Filter

This paper presents a new permanent magnet synchronous motor (PMSM) drive technique using adaptive state estimator for high-performance motion control to estimate the instantaneous speed, position and disturbance load torque. In the proposed algorithm, the model reference adaptive control (MRAC) method is incorporated to identify the variations of inertia moment, and the identified inertia is used to adapt the extended Kalman filter (EKF), which is an optimal state estimator to provide good estimation performance for the rotor speed, rotor position and disturbance torque with low precision quadrature encoder in a random noisy environment. In addition, the disturbance–rejection ability and the robustness to variations of the mechanical parameters are discussed and it is verified that the system is robust to the modeling error and system noise. Simulation and experimental results confirm the validity of the proposed estimation technique.

Design Fabrication & Real Time Vision Based Control of Gaming Board

This paper presents design, fabrication and real time vision based control of a two degree of freedom (d.o.f) robot capable of playing a carom board game. The system consists of three main components: (a) a high resolution digital camera (b) a main processing and controlling unit (c) a robot with two servo motors and striking mechanism. The camera captures the image of arena and transmits it to central processing unit. CPU processes the image and congregate useful information using adaptive histogram technique. Congregated information about the coordinates of the object is then sent to the RISC architecture based microcontroller by serial interface. Microcontroller implements inverse kinematics algorithms and PID control on motors with feedback from high resolution quadrature encoders to reach at the desired coordinates and angles. The striking unit exerts a controlled force on the striker when it is in-line with the disk and carom hole (or, pocket). The striker strikes with the disk and pots (to hit (a ball) into a pocket) it in the pocket. The objective is to develop an intelligent, cost effective and user friendly system that fulfil the idea of technology for entertainment.

Monitoring of Velocity of Manufacturing Machines Subassemblies by Means of a DAQ System

The paper deals with design of data acquisition (DAQ) systems and application of quadrature encoders in order to measure velocity of subassemblies of manufacturing machines for diagnostic purposes. Cooperation of general-purpose counter/timer boards with the quadrature encoders during measurements was discussed. Operating principles of three different measuring modes were compared. Some conclusions should be taken into account when a DAQ application has to be developed, for instance, in LabVIEW and when the needed hardware has to be selected.

Development and Implementation of a Simplified Tool Measuring System

This paper presents a simplified system for measuring geometric profiles of end mills. Firstly, a CCD camera was used to capture images of cutting tools. Then, an image acquisition card with the encoding function was adopted to convert the source of image into an USB port of a PC, and the image could be shown on a monitor. In addition, two linear scales were mounted on the X-Y table for positioning and measuring purposes. The signals of the linear scales were transmitted into a 4-axis quadrature encoder with 4-channel counter card for position monitoring. The C++ Builder was utilized for designing the user friendly human machine interface of the measuring system of tools. There is a cross line on the image of the interface to show a coordinate for the position measurement. Finally, a well-known tool measuring and inspection machine was employed for the measuring standard. This study compares the difference of the measuring results by using the machine and the proposed system. Experimental results show that the percentage of measuring error is acceptable for some geometric parameters of the square or ball nose end mills. Therefore, the results demonstrate the effectiveness of the presented approach.

Vision-Based Robotic Motion Control for Non-autonomous Environment

A visual servo control system with SOPC structure is implemented on a retrofitted Mitsubishi RV-M2 robotic system. The hardware circuit has the functions of quadrature encoder decoding, limit switch detecting, pulse width modulation (PWM) generating and CMOS image signal capturing. The software embedded in Nios II micro processor has the functions of using UART to communicate with PC, robotic inverse kinematics calculation, robotic motion control schemes, digital image processing algorithm and gobang game AI algorithm. A CMOS color image sensor is used to catch the environment time-varying change for robotic vision-based servo control. A gobang game is planned to investigate the implementation problem of the visual servo robotic motion control in non-autonomous environment. A model-free intelligent self-organizing fuzzy control (SOFC) strategy is employed to design the robotic joint controller. A vision based trajectory planning algorithm is designed to calculate the desired angular positions or trajectory of each robotic joint. The experimental results show that this visual servo control robot has reliable control actions.

Design and Implementation of a High-Performance PMLSM Drives Using DSP Chip

This paper presents a digital signal processor (DSP)-based high-performance controller for use in permanent magnet linear synchronous motor (PMLSM) drives. The PMLSM is mathematically modeled and the vector control scheme is used in the current loop of a PMLSM drive. Then, to increase the drive's performance, an adaptive fuzzy controller constructed by a fuzzy basis function and a parameter-adjustable mechanism is derived and applied to the position loop of the PMLSM drive to cope with the dynamic uncertainty and external load effect. Finally, a TMS320F2812 DSP chip produced by Texas Instruments is employed to implement the controller. The new-generation TMS320F2812 exhibits fast computation (150 MIPS) and a completely integrated motor peripheral circuit. Therefore, a fully digital controller for PMLSM drives, in which the current vector control scheme, space vector pulse width modulation generation, A/D conversion, coordinate transformation, quadrature encoder pulse detection, adaptive fuzzy controller, and point-to-point motion controller can be realized within a single DSP chip. An experimental system is established using a PMLSM, a DSP control board, an inverter, a rectifier, and other elements to verify the effectiveness of the proposed high-performance control system. Some experimental results are confirmed theoretically.

FPGA realization of adaptive speed control IC for PMSM drive

This paper presents an adaptive speed control IC for use in a PMSM (Permanent Magnet Synchronous Motor) drive based on FPGA (Field Programmable Gate Array) technology. Firstly, PMSM is mathematics modelled and the vector control scheme is introduced in the current loop of the PMSM drive. Secondly, to increase the performance of the PMSM drive, an AFC (Adaptive Fuzzy Controller) constructed by a fuzzy basis function and a parameter adjustable mechanism is derived and applied to the speed loop of a PMSM drive to cope with the effect of the system dynamic uncertainty and external load. Thirdly, a proposed adaptive speed control IC based on the FPGA is employed to realize the aforementioned current vector controller and adaptive speed controller of PMSM drive. In addition, a FSMD (Finite State Machine with a Datapath) is presented to model the overall AFC algorithm. As a result, a fully digital controller, including the AFC, the current vector scheme, SVPWM (Space Vector Pulse Width Modulation) generation, coordinate transformation and QEP (Quadrature Encoder Pulse) detection, for PMSM drive can be realized within a single FPGA chip. Finally, an experimental system is set up and some experimental results are demonstrated.

Position Sensing in Brake-By-Wire Callipers Using Resolvers

Recent designs for brake-by-wire systems use "resolvers" to provide accurate and continuous measurements for the absolute position and speed of the rotor of the electric actuators in brake callipers (permanent magnet DC motors). Resolvers are absolute-angle transducers that are integrated with estimator modules called "angle tracking observer" and together they provide position and speed measurements. Current designs for angle-tracking observers are unstable in applications with high acceleration and/or speed. In this paper, we introduce a new angle-tracking observer in which a closed-loop linear time-invariant (LTI) observer is integrated with a quadrature encoder. Finite-gain stability of the proposed design and its robustness to three different kinds of parameter variations are proven based on theorems of input-output stability in nonlinear control theory. In our experiments, we examined the performance of our observer and two other methods (a well-known LTI observer and an extended Kalman filter) to estimate the position and speed of a brake-by-wire actuator. The results show that because of the very high speed and acceleration of the actuator in this application, the LTI observer and Kalman filter cannot track the rotor position and diverge. In contrast, with a properly designed open-loop transfer function and selecting a suitable switching threshold, our proposed angle-tracking observer is stable and highly accurate in a brake-by-wire application

Adaptive online correction and interpolation of quadrature encoder signals using radial basis functions

This paper considers the development of an adaptive online approach for the correction and interpolation of quadrature encoder signals, suitable for application to precision motion control systems. It is based on the use of a two-stage double-layered radial basis function (RBF) neural network. The first RBF stage is used to adaptively correct for the imperfections in the encoder signals such as mean, phase offsets, amplitude deviation and waveform distortion. The second RBF stage serves as the inferencing machine to adaptively map the quadrature encoder signals to higher order sinusoids, thus, enabling intermediate positions to be derived. Experimental and simulation results are provided to verify the effectiveness of the RBF approach.

An Adaptive Kalman Filter with Quadrature Encoder Quantisation Compensation

An adaptive Kalman filter was designed to shape the covariance of a quadrature encoder signal to achieve better performance under measurement quantisation. Both temporal and system state measurements were used to predict the measurement noise of the encoder. Results show that the new adaptive filter produces more accurate results while requiring a lower resolution encoder than a similarly designed conventional Kalman filter intended to remove quantisation noise. An example with simulated output is presented to show the performance of the new filter.

VHDL을 이용한 향상된 기능을 가지는 모터 제어용 주변장치의 통합 설계

For the convenient use of high performance microprocessor in motor control, peripheral devices are needed for converting its control signals to compatible ones for motor drive. Customized devices are not plentiful far these purposes and their functions do not usually satisfied designers specification. The designers used to implement these functions on FPGA or CPLD using hardware description language. Then, in this case unessential programs are needed for control the peripherals. In this paper, a unified device model that links peripheral devices, including especially the pulse width modulation controller and the quadrature encoder interface device, to an interrupt controller is proposed. Advanced functions of peripherals could be achieved by this model and unessential programs can be simplified. Block diagrams and flowcharts are presented to illustrate the advanced functions. This unified device was designed using VHDL. The simulation results were presented to demonstrate the effectiveness of the proposed scheme.

New interpolation method for quadrature encoder signals

This paper presents a new interpolation method suitable for increasing the measurement resolution obtainable from quadrature encoder signals. Based on the existing sinusoidal signals, high-order sinusoids can be derived, from which binary pulses can be generated, which can be decoded using only standard servo controllers for position information. A look-up table, constructed off-line, serves as the inferencing engine for the proposed method. Imperfections in the encoder signals can be directly compensated for in the look-up table, including mean and phase offsets, amplitude difference, and waveform distortion. Simulation and experimental results are provided in this paper.