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This paper focuses on active wire tension control of motor winding machines.An ILSMC scheme for wire tension control is developed.A disturbance observer is used to implement sensorless wire tension control.The estimated wire speed is exploited in designing the tension control scheme.The stability and convergence proof of the proposed approach is provided. One of the most crucial factors that affects the winding quality in an automatic motor winding process is the regulation of wire tension. Most commercial automatic motor winding machines use passive devices such as a dancer arm or a hysteresis brake to adjust the wire tension. However, as the winding speed increases, these passive devices may not be able to react quickly enough to maintain constant wire tension and may cause the enameled wire to tremble. In order to cope with the aforementioned problems, this paper conducts an in-depth study on active wire tension control of automatic motor winding machines. In particular, an iterative learning sliding mode control scheme for wire tension control is developed in this paper, while a disturbance observer is employed to estimate the wire tension for the implementation of sensorless wire tension control. Moreover, due to the fact that the motion of the unwind roll is affected by the motion of the enameled wire, the estimated wire speed information is exploited in the design of the tension control scheme to lessen the lag phenomenon. Results of the winding experiments verify the effectiveness of the proposed wire tension control scheme.

This paper focuses on the design and analysis of the single-phase Low-Frequency Active Power Factor Correction (LFAPFC) circuit. The LFAPFC circuit has several attractive features such as low electromagnetic interference, low switching frequency and ease of implementation when compared with the High-Frequency Active Power Factor Correction circuit. Moreover, its performance is much better than that of the Passive Power Factor Correction circuit. However, few of the previous studies focus on determining the values of major parameters of the LFAPFC circuit and their corresponding performance. To conduct an in-depth study on the LFAPFC circuit, this paper proposes a systematic design method based on analyzing the characteristics of a symmetric trapezoidal current waveform. Using the proposed method, output performance indices such as total harmonics distortion and power factor of the LFAPFC circuit can be estimated. In addition, the relationship among the output performance, inductance and conduction parameters of the power switch is derived and investigated. Using the proposed method, designers can determine suitable values of conduction parameters and inductance for specific applications. Computer simulations and real experiments are carried out to verify the effectiveness of the proposed method.

One of the commonly used approaches to avoid the short circuit of power devices for pulse-width-modulation (PWM) inverters is to add dead-time into the control signals. The drawback of this approach is that severe distortion in phase currents and output voltages may occur. This paper proposes an adaptive-linear-neuron based nonlinearity compensation strategy to cope with the disturbance voltage caused by dead-time effects. In particular, by minimizing the feedback d-axis current error, the amplitude of disturbance compensation voltage V dead is self-tuned using the least mean square algorithm. The dead-time compensation method developed in this paper does not need any information about electric parameters and phase current polarity. Moreover, the proposed approach is also free of complex mathematical computations and additional hardware. Experimental results indicate that the proposed dead-time compensation approach is feasible.

Due to issues such as limited space, it is difficult if it is not impossible to employ a position sensor in the drive control of high-speed micro PMSMs. In order to alleviate this problem, this paper analyzes and implements a simple and robust position sensorless field-oriented control method of high-speed micro PMSMs based on the sliding-mode observer. In particular, the angular position and velocity of the rotor of the high-speed micro PMSM are estimated using the sliding-mode observer. This observer is able to accurately estimate rotor position in the low speed region and guarantee fast convergence of the observer in the high speed region. The proposed position sensorless control method is suitable for electric dental handpiece motor drives where a wide speed range operation is essential. The proposed sensorless FOC method is implemented using a cost-effective 16-bit microcontroller and tested in a prototype electric dental handpiece motor. Several experiments are performed to verify the effectiveness of the proposed method.

This paper proposes a recurrent fuzzy cerebellar model articulation controller (RFCMAC) for a dual-axis micromotion stage powered by piezoelectric actuators. The proposed RFCMAC employs an adjustable input space quantization method with a learning rate capable of self-tuning. The proposed RFCMAC is aimed at dealing with the adverse effects due to unknown hysteresis nonlinearity, modeling uncertainty, and external disturbance that are commonly found in the piezoelectric actuator systems. The proposed RFCMAC mainly focuses on overcoming the drawbacks of the conventional CMAC control scheme when used to control a piezoelectric actuator system. In particular, the adjustable input space quantization method uses a simple repartitioning decision function to determine an appropriate input space quantization. In addition, the self-tuning law for the learning rate of the proposed RFCMAC is derived based on the discrete-time Lyapunov function so that convergence and faster learning can be guaranteed. Finally, in order to validate the effectiveness of the proposed control methodology, several contour-following experiments were conducted on a dual-axis piezoelectric actuated micromotion stage. Experimental results show that the proposed control scheme is feasible, and its performance is superior to that of the conventional CMAC control scheme.

In many industry applications, industrial manipulators are frequently used to perform repetitive missions such as pick-and-place tasks for packing and placing objects. In general, the position information is essential when performing pick-and-place tasks. One way to obtain position information is to exploit computer vision techniques to retrieve 3D position information of objects through object images. Therefore, the relationship between object images and 3D positions of objects, and the relationship between object poses and object grasping methods are important research topics deserving more investigations. As a result, this paper focuses on research topics related to vision based object grasping of industrial manipulators, including object pose estimation, hand-eye calibration and coordinate transformation. In this paper, an eye-to-hand stereo camera system is used to retrieve object's 3D position information that is needed in pick-and-place tasks performed by an industrial manipulator. Experimental results indicate that an industrial manipulator equipped with the developed vision system can successfully perform automatic pick-and-place tasks.

Contour following motions are commonly seen in industrial manufacturing, in which the quality of manufacturing/product closely depends on the accuracy of contour following motions. In general, contour following accuracy will be affected by factors such as dynamics incompatibility among different axes and external disturbances. In order to cope with this problem, this paper proposes a new motion control scheme that consists of a well-known cross-coupled controller (CCC) and an adaptive disturbance compensator (ADC). In particular, the proposed motion control scheme is mainly used to suppress external disturbance and also cope with the problems of modeling uncertainty and dynamics incompatibility among different axes. Moreover, in order to further enhance the effectiveness of the proposed motion control scheme, the parameter-based contour error estimation algorithm is employed in this paper to provide accurate contour error information to the cross-coupled controller. Several contour following experiments conducted on a two-axis motion stage are used to assess the effectiveness of the proposed control scheme.

The motion accuracy and performance of piezoelectric actuators (PEA) are hampered by their inherent hysteresis nonlinearity and time-varying parameters. In order to overcome these drawbacks, an integrated motion control scheme is developed in this paper. In the proposed controller scheme, for each axis of the micro motion stage, a fuzzy CMAC feedforward controller combined with a conventional proportional-integral (PI) feedback controller and a critic-based learning mechanism (FCMAC-CLM) is used to improve the tracking performance and deal with the adverse effects due to hysteresis nonlinearity and external disturbance. In addition, one of the most important issues in the contour following tasks performed by a dual-axis micro motion stage is the contour error reduction. In order to improve the contouring accuracy, a fuzzy CMAC that is capable of real-time learning and self-adjusting is exploited to develop a fuzzy CMAC cross-coupled controller (FCMAC-CCC). Several experiments have been conducted to evaluate the tracking performance and contour accuracy of the proposed approach.

One of the key issues regarding multi-axis contour following tasks in modern high-precision machining applications is how to effectively reduce contour error. Generally, among existing approaches, the Cross-Coupled Control (CCC) structure is widely used in multi-axis contour following tasks to improve contouring accuracy. However, when a servomechanism is operated in reverse or low-speed motions, the inherent friction force and external disturbance effects will degrade the CCC performance. Therefore, to cope with the aforementioned problems, this paper exploits the Karnopp friction model-based compensator and the Virtual Plant Disturbance Compensator (VPDC) to improve tracking performance as well as contouring accuracy. Moreover, an integrated motion control scheme is also developed to further improve contouring performance. The proposed scheme consists of two position loop controllers with velocity command feedforward, a modified CCC, two friction force compensators, and two disturbance compensators. To evaluate the performance of the proposed approach, several free-form contour following experiments have been conducted on an X-Y table driven by two linear motors. Experimental results verify that the proposed approach can significantly enhance contouring performance for free-form contour following tasks.

In this paper, an adaptive disturbance compensation (ADC) scheme for the speed control of a servomechanism is proposed. The idea of the proposed ADC is to adaptively adjust the compensator gains so that the output of the actual plant after compensation will faithfully follow the output of the nominal model. The major benefits of the ADC are twofold — disturbance/uncertainties attenuation and load torque estimation. The stability of the proposed ADC is verified by Lyapunov stability analysis. In addition, an integrated motion control structure consisting of the proposed ADC, a feedback controller and a friction compensator is developed to deal with the contour following problem. In this paper, the friction compensator designed based on the LuGre friction model is used to effectively reduce the large contouring error that often occurs when there is a reverse motion. Two experiments have been conducted to verify the effectiveness of the proposed approach. The test bench of the load torque estimation experiment consists of a servo motor and a hysteresis dynamometer, while the contour following experiment is conducted on an X–Y table. Experimental results show that the proposed approach exhibits satisfactory performance.

Automatic optical fiber alignment is the key to reducing the cost of the packaging process for the manufacturing of fiber-optic devices. This paper develops a vision-based active optical fiber alignment technique for coarse positioning using a piezoactuated moving platform that is controlled to reduce the alignment difference to within a certain degree. To overcome the adverse effect of the delay time between the motion control system and the vision system, the methodology based on the multirate control scheme is presented. Experimental results verify the effectiveness of the proposed approach.

The cross-coupled control (CCC) is considered to be the most popular approach to reducing contouring error for biaxial contour following tasks. Using the CCC concept as a starting point, this paper will then develop the position error compensator (PEC) approach to reduce contour error. The main advantage of the proposed approach is that it can simultaneously improve tracking and contouring performances by compensating position errors in advance. Moreover, to further reduce the contour error, an integrated motion control scheme consisting of the proposed PEC, a modified version of CCC, and a fuzzy-logic-based feedrate regulator is employed. Several free form contour following experiments have been conducted. Experimental results demonstrate that the proposed approach can significantly reduce the contouring error for biaxial contour following tasks.

In contrast to hybrid electric cars (HECs), the issues concerning cost, volume, and reliability are even more rigorous when developing hybrid electric scooters (HESs). Therefore, the drive topology and control strategy used in HEC cannot be applied to HES directly. This paper presents a single-stage bidirectional dc/ac converter based on a general full-bridge inverter. The converter is designed for a low-voltage brushless dc motor/alternator (BLDCM/A) used in HESs, in which the additional bulky inductor and power switches are eliminated in the proposed design. In order to increase the reliability of the commutation process, a cost-effective sensorless control scheme for the motor and alternator commutation is developed. The commutation signals are extracted directly from the average terminal voltages, in which the motor neutral voltage, multistage analog Alters, analog-to-digital converters, and the complex digital phase-shift (delay) circuits are eliminated. In addition, instead of using the complex flux- weakening control technique, the winding-changeover technique is exploited to extend the range of the operating speed. With attractive features, such as low cost and ease of implementation, the proposed approach is particularly suitable for electric bikes, electric scooters, HESs, etc. Theoretical analysis and several experiments are conducted to justify the effectiveness of the proposed method.

This paper presents the analysis, design, and implementation of a high performance and cost effective sensorless control scheme for the extensively used brushless dc motors. In an effort to decrease cost and increase ease of implementation, the commutation signals are obtained without the motor neutral voltage, multistage analog filters, A/D converters, or the complex digital phase shift (delay) circuits which are indispensable in the conventional sensorless control algorithms. In the proposed method, instead of detecting the zero crossing point of the nonexcited motor back electromagnetic force (EMF) or the average motor terminal to neutral voltage, the commutation signals are extracted directly from the specific average line to line voltages with simple RC circuits and comparators. In contrast to conventional methods, the neutral voltage is not needed; therefore, the commutation signals are insensitive to the common mode noise. Moreover, the complex phase shift circuit can be eliminated. As a result, the proposed control algorithm can be easily interfaced with the cost effective commercial Hall effect sensor based commutation integrated circuits. Due to its inherent low cost, the proposed control algorithm is particularly suitable for cost sensitive products such as air purifiers, air blowers, cooling fans, and related home appliances. Theoretical analysis and experiments are conducted over a wide operating speed range and different back EMF waveforms to justify the effectiveness of the proposed method

An iterative error compensation approach is proposed in this article to improve the accuracies of high speed, computer-controlled machining processes. It is well known that the high-speed computer-numerically-controlled (CNC) machines are extremely useful in terms of manufacturing mass-produced parts. The proposed method uses an iterative learning technique that adopts the servo commands and cutting error experienced in previous maneuvers as references to current compensative actions. Moreover, non-repetitive disturbances and nonlinear dynamics of the cutting processes, and servo systems of the CNC machine that greatly affect the convergence of the learning-control systems were also studied in this research. State feedback and output feedback techniques were adopted in the proposed controller design. In addition to the stability analysis, a 1 degree-of-freedom servo positioning system is constructed to evaluate the performance of our proposed learning control approach. Both the simulation and experimental results verify the effectiveness of our approach.

For most of the virtual reality system, one of the major aims is to provide a vivid interaction platform between the human operators and the haptic devices. Through the user interface, a skilful operator can control the haptic devices to accomplish relatively complicated jobs in real-time. Generally, the main components of a virtual reality system include dynamic simulations, haptic devices and the user interface, which is composed of virtual environments and visual equipment. This study focuses on developing a virtual tennis entertainment system with haptic behaviour. A parallel-type robot and a serial-type robot are employed as the haptic device handlers in this study, in which they are controlled directly by the operator's arm through the user interface. The operator can sense the change in virtual environment provided by dynamic simulations. In addition, the human operator can ‘see’ the change of environment during operation in real-time through the screen. A virtual spring model and a virtual damper model were constructed to simulate the process of tennis playing in this study. Experimental results verify the feasibility of the proposed virtual tennis entertainment system.

Motion controllers play a pivotal role in the development of high-performance CNC machines. Precision motion control is achieved with a control structure employing S-curve motion planning on the velocity command before interpolation, command feedforward and friction feedforward compensation. To evaluate the performance of the proposed control scheme, a servomechanism is controlled to track a circular curve in the form of nonuniform rational B-splines, where the desired motion information such as velocity and acceleration are also provided. Experimental results indicate that the proposed motion-control structure exhibits a better performance, when compared with conventional motion-control schemes.

Due to the fact that the cutting occurs around the cutter contact (CC) point, the efficiency and quality of CNC machining can be improved significantly if the CC velocity along the surface is kept costant. Conventional approaches to machining mainly maintain a constant cutter location (CL) velocity, so that the CC velocity along the surface is often not constant and usually results in non-uniform machining and unsatisfactory quality. To overcome this difficulty, this paper presents a novel NURBS surface interpolator that is capable of real-time generation of CL motion command for ball-end milling of NURBS surfaces and maintaining a constant CC velocity along the CC path and its intervals. For performance evaluation, a three-axis servomechanism driven by three servomotors is controlled to track segments represented by NURBS surfaces. Experimental results verify the effectiveness of the proposed method.

This study explores the feasibility of variable feedrate parametric interpolators for real-time motion command generation using a digital signal processor (DSP). Most of the existing parametric interpolators are developed for a constant federate due to the computational complexity. However in certain applications, in order reduce the deterioration in accuracy of machining, feedrate commands should be performed in advance to overcome excessive acceleration/deceleration of CNC machines. The aim of this study is to develop a real-time parametric interpolator with variable federate where acceleration/deceleration planning on the feedrate command is performed before the interpolation takes place. This approach that would provide new capabilities for advanced CAD/CAM systems, can compensate for the path command error caused by the acceleration/deceleration after interpolation. To justify the performance of the real-time control interpolator, an X-Y table driven by two servomotors is controlled to track a parametric curve represented in non-uniform rational B-Spline (NURBS) form.

In order to automatically identify the electrical parameters of PMSMs, rather than measure the parameters using instruments such as RLC meters, this paper proposes an approach in which the testing voltage is injected into the motor from the drive. Based on the analysis of equivalent circuits of the PMSMs as well as the phase voltage and phase current information recorded from standstill to sensorless control operation, the RLS method is employed to estimate the values of electrical parameters of the PMSMs. Moreover, the automatic motor parameter identification algorithm developed in this paper is also integrated into the open loop startup procedure of the sensorless control drive. Consequently, the proposed automatic motor parameter identification method has attractive features such as fast identification and being highly convenient. In addition, both the proposed automatic motor parameter identification method and the sensorless control drive developed in this paper are implemented using a low-cost 16-bit microcontroller. Two commercial surface-type and interior-type PMSMs are used in the experiments to assess the performance of the proposed approach. Experimental results verify the effectiveness of the proposed automatic motor parameter identification method.

Conventional motor winding machines use a passive device such as a dancer arm or hysteresis brake to adjust the tension of the wire. However, when the winding speed increases, the passive device may not be able to react quickly enough so that a sudden change in the tension will likely cause the enameled wire to vibrate. Consequently, the motor winding quality will be affected. In order to cope with this difficulty, instead of using a passive device, this paper proposes an active tension control scheme, in which the wire tension measured by a load cell is used as the feedback signal of the tension control loop. Moreover, feedforward control and iterative learning control are integrated into the proposed tension control scheme to improve system response and suppress the periodic disturbance arising from the winding process. Several motor winding experiments have been conducted to assess the performance of the proposed approach.

Due to attractive features such as low cost and highly robust, the demand for Switched Reluctance Motors has reached an all-time high. However, the torque ripple caused by the inherent double salient structure of SRMs leads to speed ripple as well. In order to cope with the aforementioned torque/speed ripple problem, many studies rely on sophisticated control techniques. However, in most of the previous studies the powerful Digital-Signal-Processor is used to realize these sophisticated control schemes since their complicated structures require massive computing power. The fact that the DSP-based solution is not cost effective results in a conflict with the original benefits of SRMs. To cope with the aforementioned problems, this paper employs a variable gain PI-type controller to suppress the torque ripples of SRMs. In order to have a cost effective solution, all the motor drive algorithms and control schemes are implemented using a low cost microcontroller in this paper. Experimental results show that the torque ripple has been significantly reduced so as to verify the effectiveness of the proposed control approach.

In manufacturing processes, human error and abnormal operation often result in excessive loads on the servomechanisms. To prevent the abnormal load from damaging the work piece or tool, it is important to find a means to detect the abnormal load so that an appropriate response can be performed. To estimate the load on the servomechanism, two types of torque observer structures are presented in this study. Based on the information obtained from the torque observer, criteria are proposed to determine whether the servomechanism is under the abnormal load, while the Wavelet analysis is employed to enhance the ability of abnormal load detection. Experimental results indicate that the presented observer structures are able to estimate the external torque accurately. In addition, the structure combined with Wavelet analysis is capable of identifying abnormal load events in servomechanisms.

This paper explores the bifurcation behavior of a buck-boost converter. Unlike the previous research, the nonlinearity of the MOSFET and the diode are taken into account when modeling the dynamic equations of the converter. In the simulation, bifurcation points are computed and compared with the ones calculated with the piecewise-linear model and the software SIMPLIS. The simulation results reveal that our model best represents the true behavior of the converter. Moreover, engineers can predict more precisely the occurrence of instability with this model.

Power assisting devices can be found in many different applications, most notably, exercise/fitness equipment, rehabilitation of spinal cord injury or stroke patients, limb muscle enhancement of workers, and bionic limbs of amputee patient. Since the power assisting device has a direct contact with the human user, in addition to providing suitable amount of assisting force, the highest priority in the design of power assisting devices is to ensure the safety of the human user. In order to fulfill such a requirement, in this paper an impedance controller and a passive velocity controller are combined to provide moderate amount of assisting force and also ensure the safety of the user simultaneously. Moreover, a torque observer is used to estimate the torque generated by the user's muscle rather than using a force sensor to measure the contact force between the user and the power assisting device. Experimental results verify the effectiveness of the observer-based impedance controller and the passive velocity controller.

The ability to sustain a smooth-running practice is very important in dentistry. Because of this reason, Electric handpieces driven by permanent magnetic synchronous motors (PMSMs) have been increasingly applied in dentistry and have replaced air-driven ones due to their high efficiency and ability to sustain constant speed while operating. Additionally, they produce little noise compared to the high pitched whine of their air-driven counterparts. As is well known, the rotor position is the necessary information for driving a PMSM. Unfortunately, a dental handpiece requires repeated heat sterilization that will break down the Hall sensors, and further, lacks the space to install an incremental encoder. Therefore, sensorless speed control of a PMSM is the key technology for an electric dental handpiece. In this paper, a sliding mode observer is used to implement an electric dental handpiece. Moreover, a prototype of the electric handpiece system has been designed and built. Experimental results are presented to verify the feasibility.

In high-precision manufacturing, the paramount issue is to diminish contour error regarding multi-axis contour following tasks. In particular, machining problems such as large contouring errors will likely occur in a complex shape machining task due to the inherent friction force and/or external disturbances. Among the possible solutions to dealing with this difficulty, the Cross-Coupled Controller (CCC) is arguably the most commonly used approach for contouring accuracy improvement in multi-axis contouring control systems. Therefore, to attain satisfactory contouring accuracy, this paper exploits the CCC approach for control of free-form contour following tasks in biaxial motion control systems. Additionally, a Fuzzy Logic-based Disturbance Compensator (FLDC) is presented to enhance tracking performance as well as contouring accuracy. Moreover, an integrated motion control structure consisting of a modified version of CCC and two proposed FLDCs is further developed in this paper to improve contouring performance. Several experiments on free-form contour following tasks have been performed on an X-Y table driven by two linear motors. Experimental results validate the feasibility of the proposed approach.

In this paper, a cost effective single stage bidirectional DC/AC converter is designed and implemented using a general full-bridge inverter without any additional power switches or bulky passive components. According to different driving conditions, three switching strategies are developed and analyzed. These switching strategies, which are named after the operating number of the power switches, are called the single-switch, two-switches and three-switches control strategies. Different performance indexes such as boost ratio, maximum voltage conversion ratio, braking torque, etc., are proposed and compared among different switching strategies. Theoretical analysis and experimental results have revealed that the cruising distance, braking torque, and reliability can be improved effectively using a variable braking control strategy according to the driving conditions. Since the additional power switches, passive components and costly position sensors are not required, the proposed method is particularly suitable for various light electric vehicles.

Due to its attractive features such as high power density, long duration, high efficiency, the Brushless DC Motor (BLDCM) has gradually replaced the conventional brush DC motor and has been widely used in home appliances, office equipments, industrial applications and vehicles, etc. This paper proposes an intellectual property design of functions needed to implement a BLDCM drive, including the algorithms for commutation and control. The developed IP is verified by an Altera FPGA Board. In addition, the IP developed in this paper can be implemented as an Application Specific Integrated Circuit (ASIC) or embedded in SoC IC as a motor drive module. It is cost effective and requires shorter development time compared with the conventional microcontroller drive.

Most modern commercial electric scooters are still equipped with the DC brush motor. This type of motor has mechanical structures such as permanent magnet, brush, and commutator. Therefore, it has attractive features, e.g., large start-up torque and easy to control. However, this kind of mechanical commutation often leads to drawbacks such as low power density, low reliability, and poor heat dissipation. In contrast, the Permanent Magnet Brushless Motors (PMBLMs) have advantages such as high efficiency and maintenance free, etc. Hence, the PMBLMs have great potential in becoming the actuators for electric scooters. In this paper, the performance of the PMBLMs with trapezoidal and sinusoidal back-emf waveforms driven by square wave commutation and sinusoidal commutation is investigated. To reduce the cost, low-resolution Hall sensors are used to implement sinusoidal commutation.

Generally, friction/disturbance compensation is an important issue in high-precision motion control applications. In particular, when the system under control undergoes low-speed or reversal motions, the friction force and external disturbances will degrade motion accuracy. Therefore, to achieve satisfactory motion performance, it is necessary to simultaneously compensate for the friction force and external disturbances. In this paper, an integrated motion control scheme consists of a PI-type feedback controller, a friction compensator based on the LuGre model, and a Virtual Plant Disturbance Compensator (VPDC) is developed. In particular, the VPDC is proposed to replace the PI-type Closed-loop Torque Observer (PICTO) since the latter may provide inaccurate information when used in disturbance compensation. Several experiments on load torque estimation and speed control are conducted in order to evaluate the performance of the proposed approach. Experimental results demonstrate the effectiveness of the proposed approach.

This paper presents a novel two-stage electronic ballast for metal-halide (MH) lamps. The front stage is a single-switch boost and buck-boost integrated converter. The post stage is a half-bridge inverter driving the MH lamps with low-frequency square-wave current. The operating principle of the proposed topology is discussed. Also, constant power control is realized using the methodology employed for peak inductor current control. Finally, a laboratory prototype of a 70W electronic ballast for MH lamp operated with universal input voltage is implemented to verify the feasibility.

In this paper, a vision-based optical fiber alignment motion stage powered by Piezo-Actuator (PEA) is developed. However, the tracking performance of PEA is limited due to its inherent hysteretic nonlinearity and time varying parameters. In order to cope with this problem, a novel feedforward inverse hysteresis model based on B-spline approximation is adopted to eliminate the adverse effects due to hysteresis. In addition, a fuzzy logic controller is designed to reduce the error caused by noise and modeling inaccuracy. Moreover, the idea of multi-rate control is exploited to deal with the vision latency problem. The feasibility of the proposed control scheme is verified under a variety of reference inputs. Experimental results show that the proposed approach exhibits satisfactory performance.

Optical fiber communication has become mainstream in wired communication due to its low attenuation, low cost, and high bandwidth. However, optical fiber is light and thin, which makes the coupling procedure between fibers and optoelectronic components very complex and difficult. To maintain high transmission quality, it is imperative to develop a high-precision alignment technique for optical fiber fabrication. In this paper, a vision-based optical fiber alignment stage powered by a piezo-actuator (PEA) is proposed. The tracking performance of PEA is limited due to its inherent hysteretic nonlinearity and time varying parameters. In order to cope with this problem, a feedforward compensator based on a cerebellar model articulation controller (CMAC) combined with a PI feedback controller is developed to eliminate the effects of hysteresis. Multi-rate control is used to deal with the vision latency problem. Experimental results show that the proposed approach shows satisfactory performance.

Automatic optical fiber alignment is the key to reduce the cost of the packaging process for the manufacture of fiber-optic devices. This study develops a vision-based active optical fiber alignment technique using a piezo-actuated moving platform which is controlled to reduce the alignment difference to a certain degree. In the proposed approach, the centroid of the optical fibers to be aligned can be determined from the captured image so that the line equations for the optical fibers as well as the alignment differences can be obtained. To overcome the adverse effect from the delay time between the motion control system and vision system, the methodology based on the multirate control scheme is presented. Experimental results verify the effectiveness of the proposed approach.

In order to improve the efficiency of the conventional home appliances, brushless DC motors with variable speed controller have been extensively applied to various home appliances, such as air-conditioners, refrigerators, washing machines, etc. However, existing literatures concerning power factor correction (PFC) for home appliances are limited. In this paper, a practical approach is proposed to deal with problems such as harmonic distortion and poor power factor so that the great demand of PFC in variable speed home appliances can be satisfied. A high power factor and low current harmonic distortion PFC circuit is developed based on the idea of low switching frequency asymmetric pulse width modulation (Asy-PWM). Compared with the well-known high frequency active PFC circuits, high switching loss and heavy EMI filters can be eliminated. Theoretical analysis, computer simulation, and experimental results all have demonstrated the effectiveness of the proposed method.

This study focuses on the development of a vision- based treadmill system that is actuated by a permanent magnet synchronous motor (PMSM). The PMSM employed in our design is free of commutation spikes and maintenance, so that it can replace the DC motor that is often adopted in the conventional treadmill system. Moreover, to achieve a smooth low speed operation, the sinusoidal Back EMF and the SPWM are exploited to achieve sinusoidal commutation for the PMSM. In addition, two kinds of running modes - active and passive, are developed in this paper. In the active running mode, the running speed of the treadmill is set up by the user through a human-machine interface, while in the passive running mode the user can determine the magnitude of the retard force and running speed by himself/herself. To build a user friendly environment, a virtual touch panel is projected onto a screen/wall through a projector, and a vision-based motion detection algorithm is used to determine which button of the virtual touch panel is pressed by the user. In this way, without actually touching the panel, the user can operate the treadmill while running/jogging, so that greatly enhancing the convenience.

In this paper, a single-phase DC/AC inverter for uninterruptible power supply using moving sliding manifold (MSM) sinusoidal tracking control is proposed. The characteristic of the MSM over the conventional sliding manifold is capable of ensuring the sliding mode proceeds from an arbitrary initial state and thus achieves the robustness against system uncertainties. The inverter tracking performances of steady-state and transient responses can be improved due to speedup-reaching the sliding manifold. A 60 Hz 400 W prototype is built with MSM control scheme based on dSPACE DSP by sensing the output voltage for the closed-loop feedback. The experimental results show that low total harmonic distortion (THD) output voltages under resistive load or even under rectifier-RC load and fast transient response subject to step change in load are obtained. Design procedures, computer simulations, and experimental results are provided to demonstrate the performance of the MSM controlled inverter.

A high performance bidirectional DC/AC converter is required for low emission and high efficiency propulsion systems, such as electric vehicles (EVs) and hybrid electric vehicles (HEVs). In order to increase the reliability of the drive system, this paper presents the design, analysis, and implementation of a cost effective sensorless control scheme for the extensively used brushless DC motors and alternators. Taking into consideration cost and ease of implementation, the commutation signals are obtained without the motor neutral voltage, multistage analog filters, A/D converters, and the complex digital phase shift (delay) circuit which are indispensable in the conventional sensorless control algorithms. In the proposed approach, instead of detecting the zero crossing point of the non-excited phase back EMF to the neutral voltage, the commutation signals are extracted directly from the specific average line to line voltages with simple RC circuits and comparators. As a result, the proposed control algorithm can be easily implemented with the low cost CPLDs or 8-bit micro-controllers. Because of the inherent low cost property, the proposed control algorithm is particularly suitable for cost sensitive products such as electric bikes, electric scooters, hybrid electric scooters, home appliances, automotive components, etc. Theoretical analysis and experimental results show that the proposed control algorithm exhibits satisfactory performance over a wide operation range in both motor and alternator operations.

The v-belt linked pulley based continuously variable transmission (CVT) has been adopted extensively in internal combustion engine scooters (ICES) and zero emission scooters (ZES), in which CVT is used to increase the starting torque and also extend the speed operation range of the engines or motors. However, because of the inherent frictional mechanism, the efficiency of general CVT is relatively low (40%~70%), it is highly dependent on driving conditions. In this paper, instead of using the low efficiency mechanical transmission mechanism or the complex flux weakening control technique, a new winding changeover technique is proposed to increase the low speed starting torque and also extend the high speed operation range for small to midsized electric or hybrid electric drives without increasing the rated size of the power switches, or decreasing the system efficiency/reliability. By eliminating the large friction loss of the CVT and the extra copper loss accompanied with flux weakening operations, the driving performance of the ZES can be improved significantly with the proposed techniques. The additional cost required to implement the proposed approach is the inexpensive electromagnetic contactors. Consequently, the proposed approach is very suitable for most cost sensitive ZES drives. Experimental results have demonstrated that the proposed approach exhibits superior performance when compared with the conventional solutions

This paper presents the design, analysis, and implementation of a high performance and cost effective sensorless control scheme for the extensively used brushless DC motors (BLDCMs). Taking into consideration cost and ease of implementation, the commutation signals are obtained without the motor neutral voltage, multistage analog filters, A/D converter, and the complex digital phase shift (delay) circuit which are indispensable in the conventional sensorless control algorithms. Instead of detecting the zero crossing point of the non-excited phase back EMF to the neutral voltage, the commutation signals are extracted directly from the specific average terminal voltages with simple RC circuits and comparators in this study. Since the neutral voltage is not needed, the extracted commutation signal is insensitive to the common mode noise, hence the low speed performance is superior to the conventional methods. Moreover, the complex phase shift circuit has been eliminated. As a result, the control algorithm can be easily interfaced with the cost effective commercial Hall effect sensor based commutation ICs. Because of the inherent low cost property, the proposed algorithm is particularly suitable for cost sensitive products such as air purifiers, air blowers, cooling fans, and related home appliances. Theoretical analysis and experimental results show that the proposed control algorithm exhibits superior performance over a wide operation range when compared with the conventional solutions

A prototype vision-guided mobile robot that can be used in the golf practice field to pick up golf balls is developed in this study. Based on the bird-view image provided by the CCD camera mounted on top of the golf practice field, the relative positions and directions between the golf ball and the mobile robot can be determined. The obtained position and direction information are then sent to the control computer so that appropriate motion commands can be issued to the mobile robot wirelessly. Upon receiving the motion commands, a control/drive circuit developed in our lab is used to drive the mobile robot to execute the golf ball collecting task. Experimental results indicate that the developed vision-guided mobile robot exhibits a satisfactory performance.

A multi-purpose real-time visual tracking system that can be used in different scenarios has been designed and implemented in this study. This real-time visual tracking system can be operated in two modes - "static tracking" and "dynamic tracking". When operated in the static tracking mode, a modified adaptive background subtraction method is used to detect the moving object. In contrast, when operated in the dynamic tracking mode, a region-based matching approach is used to estimate the motion of the moving target and the servo control unit would be activated to control the camera motion so that the moving target's image is kept in the center of the monitoring screen. Several experiments such as "traffic monitoring", "marine creature detection", and "intruder detection/tracking" were conducted to evaluate the system's performance. Experimental results indicate that the performance of the developed real-time visual tracking system is satisfactory.

Dynamic biped walking is a difficult control problem. The design involves that of the controller as well as the gait. A typical design procedure involves tedious analysis, careful planning, and testing. The procedure is time consuming and the analysis is often based on some linearized model. Selection of control parameters and nominal trajectory determines the quality of control and in typical designs, some or all of the parameters are selected intuitively. The result is often not the best. If some special goal (such as to walk as fast as possible) is desirable, the design may become even harder. While the analytical approach is not easy, one possible alternative is to obtain the optimal or near-optimal design through parameter search. This study explores this approach. The design of the biped controller and gait is formulated as a parameter search problem, and a genetic algorithm is applied to help obtain the optimal design. Designs to achieve different goals, such as being able to walk on an inclined surface, walk at a high speed, or walk with a specified step size have been evolved with the use of the genetic algorithm. Simulation results show that the genetic algorithm (GA) is capable of finding good solutions. © 1997 John Wiley & Sons, Inc.

In contour following applications, contour error reduction is a subject of much concern. In order to attenuate the influence of modelling uncertainty and external disturbance so that satisfactory contouring accuracy can be achieved, this article develops an integrated motion control scheme that consists of a pre-defined velocity field, a velocity field controller and the proposed Adaptive Virtual Plant Disturbance Compensation (AVPDC) scheme. First, a velocity field is constructed for a free-form curve and its associated controller is also developed. Moreover, to improve the contouring accuracy, this article proposes an AVPDC to compensate for the uncertainties because of the inaccurate modelling and external disturbances. The main advantage of the proposed AVPDC is that the compensator gains can be adaptively adjusted according to the current state error. Subsequently, in order to investigate the stability of the proposed AVPDC, a Lyapunov-based analysis is performed. Finally, a free-form contour following experiment is conducted to verify the effectiveness of the proposed approach. Experimental results show that the proposed approach exhibits satisfactory performance.

A high-performance bidirectional DC/AC power converter is required in low emission and high-efficiency propulsion systems such as electric vehicles and hybrid electric vehicles. A general six-switch full-bridge inverter topology with a high efficient interior permanent magnet alternator is adopted to explore the constant-voltage, constant-current and pulsating-current charging processes. In addition, useful information such as maximum conversion ratio, average armature current, armature current ripple and output voltage ripple are derived based on the equivalent circuit model where the armature resistance of the alternator and the conduction resistance of the power switch are considered. A 32 bit digital signal processor, TI 2812, is used to implement the switching strategies and the control algorithms. Experimental results indicate that the performance of the proposed control strategy is satisfactory for all of the popular charging strategies employed. Compared with the traditional claw pole alternator, the proposed strategy exhibits a significant improvement in output efficiency.

V-belt-linked continuously variable transmissions (CVTs) find extensive use in both internal-combustion-engined and electric scooters. The CVTs are used to increase the starting torque and also extend the range of the operating speed of the vehicles. Unfortunately, the efficiency of a CVT is relatively low due to friction effects and the alternative techniques based on flux weakening control are both complex and costly to implement. To circumvent these problems a multispeed winding is designed that is able to increase the starting torque at low speeds and extend the constant-power speed ratio for small and midsized brushless DC motors. Moreover, in order to increase the reliability of the drive system, a cost-effective sensorless control algorithm is developed. The commutation signals can be directly extracted from the average terminal voltages of the motor using simple RC circuits and comparators. This means that the sensorless commutation can be implemented by simply using low-cost CPLDs or microcontrollers. The proposed approach is particularly suitable for application to cost-sensitive electric vehicles such as wheel chairs, bikes and scooters and also hybrid electric scooters. A theoretical analysis of the pattern is performed and various experiments are conducted to evaluate the effectiveness of the proposed method

Due to attractive features including a high reliability, low maintenance, and a low cost, stepping motors with an open-loop drive have found wide application in motion control systems. However, the performance of a stepping motor that is under open-loop control deteriorates when either the frequency of the input pulse train is increased or an external load is unexpectedly added. A high-performance, cost-effective direct-drive position-control system with an ironless linear permanent-magnet synchronous motor (ILPMSM) is proposed to overcome these difficulties. Instead of using a multi-loop cascaded-feedback control structure, the position is controlled by regulating the orientation and magnitude of the excited space current vector of the moving coil of the ILPMSM. Also, the effect of the dead time on the positioning accuracy is investigated and a cost-effective position-error compensation approach in the d-q plane is introduced. Compared with general hybrid stepping motors several advantages are observed when using the proposed control strategy, including: (i) the resolution of the stepping increment and the holding force are software programmable; and (ii) limited losing steps can be automatically eliminated during the travelling process. A high-performance digital signal processor is used to implement the proposed control algorithm. Experimental results verify that the proposed approach exhibits a satisfactory performance.