Browsing by Author "Liaw, Der-Cherng"

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A CAN-Based Design for the Control of Electric Vehicle
(2014)
Liaw, Der-Cherng
;
Yu, Cheng-Yu
;
Wu, Kuo-Chen
;
電機工程學系
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Department of Electrical and Computer Engineering
Due to the development of the advanced technologies, in the recent years, electronic devices for the communication and computer engineering have been considered to implement the so-called "X-by-Wire" scheme for steering control and braking control of the vehicles. It is known that the weight reduction of vehicle systems can decrease the power consumption when the traditional mechanical components can be replaced by electronic devices. Thus, X-by-wire system will be a trend in the automotive industry for saving energy. An event trigger design for vehicle control is proposed in this paper for vehicle control by using the protocol of Controller Area Network (CAN). The proposed design covers the development of CAN communication node, which is developed by using microprocessor chip Microchip PIC18F4585 and MCP2551 CAN transceiver. In addition, an interactive GUI-based utility program developer is also built up for user to easily develop the required function call to cope with the design specification. A wireless electric-driven control vehicle is served as a platform to verify the design of drive-by-wire and brake-by-wire operations. Experimental results demonstrate the success of the proposed design.
A design of mini actuator for compact camera without using permanent magnet
(2014-01-01)
Tsai, Ching-Lung
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Liaw, Der-Cherng
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents a design of mini actuator without using permanent magnet for auto-focus (AF) compact camera module (CCM) built on mobile phone, tablet PC and notebook. The current through the coils of electromagnets will yield magnetic force to move the moving part up and down. Comparing with conventional spring-type voice coil motor (VCM) and non-spring type VCM, the proposed actuator eliminates the concerns of rare earth supply and magnetic flux leakage which can fail the function of magnetic flux sensitive device such as e-compass. The proposed actuator also simplifies the power converter design from bipolar scheme as required by conventional non-spring type VCM to unipolar. A comprehensive electromagnetic analysis is performed by using finite element method to characterize the performance of the proposed actuator. Numerical simulations demonstrate that the magnetic flux leakage in the proposed actuator is much smaller than those by conventional design.
A Feedback Linearization Design for Compressor's Surge Control
(2008)
Liaw, Der-Cherng
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Ren, S. M.
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Chang, Shih-Tse
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電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, input-output feedback linearization scheme is employed to stabilize the instabilities of axial flow compressor, specifically, for the so-called "surge" behavior. Two types of actuators are considered for the study. One is the throttle opening, and the other is the close-coupled valve. The axial flow compressors are found to be feedback linearizable via either of the two control inputs. Overall control law is then proposed to prevent the occurrence of the surge oscillation. Numerical results are also given to demonstrate the effectiveness of the proposed designs.
A feedback linearization design for the control of vehicle's lateral dynamics
(2006)
Liaw, Der-Cherng
;
Chung, Wen-Ching
;
Song, Chau-Chung
;
Hsieh, Chien-Shu
;
電控工程研究所
In this paper, the feedback linearization scheme is applied to the control of vehicle's lateral dynamics. Based on the assumption of constant driving speed, a second-order nonlinear lateral dynamical model is adopted for controller design. It was observed in Liaw and Chung (2006) that the saddle-node bifurcation would appear in vehicle dynamics with respect to the variation of the front wheel steering angle, which might result in spin and/or system instability. Feedback linearization control laws are proposed in this paper to stabilize the vehicle's dynamics at bifurcation points. Numerical simulations for an example model demonstrate the effectiveness of the analytical results.
A Method for Finding the Routes of Mazes
(2018-01-01)
Wu, Chang-Ming
;
Liaw, Der-Cherng
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Lee, Hung-Tse
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電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, we propose a potential modified route-searching algorithm to find all feasible paths in a new place which is like an unknown maze. The maze-like place is assumed to be a region constructed by grids and each grid is supposed to have at most four directions for moving. A searching algorithm is developed to accomplish the required tasks for patrolling every path in the new place. Based on the traditional depth-first graph traversal method, we build up a local-maze coordinate system to record the visited pathway. The main results of this paper will give an experiment simulation to demonstrate the success of proposed design.
A method using an averaging technique for the analysis and evaluation of real quasi-resonant converters
(2006-06-01)
Lin, Yi-Cherng
;
Liaw, Der-Cherng
;
電控工程研究所
;
Institute of Electrical and Control Engineering
A method using an averaging technique for the analysis and evaluation of real quasi-resonant converters (QRC's) is proposed in this paper. To reduce the great difference between the real characteristics and those of ideal circuits, a modeling technique is developed by considering the effect of parasitic power losses. Then, using the averaging approach reasonably simplifies the process of solving equations to obtain the steady-state solutions of state variables. Also, an updating algorithm is constructed to take all the power losses such as core losses, which are often absent in the conventional analysis, into account to improve the accuracy of the steady-state solutions. By these efforts, the evaluation of characteristics for QRC's is realized.
A novel approach for characteristic evaluation of practical buck zero-voltage switching quasi-resonant converters
(2005)
Lin, Yi-Cherng
;
Liaw, Der-Cherng
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, we propose a modeling bases scheme to study the practical characteristics of Buck zero-voltage switching quasi-resonant converters (Buck ZVS-QRC's). Instead of assuming the unity power efficiency and/or having the ideal characteristics of all circuit components in most existing studies, a feasible model taking the equivalent intrinsic resistance of each circuit component and the voltages of inductors into account is used to describe the steady-state operation of the converter. By using the developed technique, the circuit equations can be simplified to obtain symbolic solutions. Then, an iterative algorithm is constructed for solving operating points. With the aid of the derived expressions, functions of operating point, a parametric analysis of practical behavioral characteristics is also realized. Experimental results demonstrate the effectiveness of the proposed method.
A SERVER LOAD BALANCING DESIGN FOR PEER-TO-PEER NETWORK
(2011)
Liaw, Der-Cherng
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Chiu, Cheng-Hsiang
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Yeh, Chia-Wei
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Chang, Chia-Ming
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Hsieh, Hsiao-Jen
A novel scheme is proposed for server load balancing. It is known that load balancing plays a critical role in network-based information service. Although lots of methods have been recently proposed, however, most of those schemes might not be able to make the loading of all servers evenly. Thus, server system might encounter the risk of being over-loaded and/or out of function. In this paper, we propose a distribution scheme to prevent the server from being over-loaded and save the power consumption of all server system for low loading request. It is shown in the paper that the proposed scheme can make the load distribution more efficiently without being over-loaded. Experimental results demonstrate the success of the proposed design.
A Server Load Balancing Design for Peer-To-Peer Network
(2010)
Liaw, Der-Cherng
;
Chiu, Cheng-Hsiang
;
Yeh, Chia-Wei
;
Chang, Chia-Ming
;
Hsieh, Hsiao-Jen
A novel scheme is proposed for server load balancing. It is known that load balancing plays a critical role in network-based information service. Although lots of methods have been recently proposed, however, most of those schemes might not be able to make the loading of all servers evenly. Thus, server system might encounter the risk of being over-loaded and/or out of function. In this paper, we propose a distribution scheme to prevent the server from being overloaded and save the power consumption of all server system for low loading request. It is shown in the paper that the proposed scheme can make the load distribution more efficiently without being over-loaded. Experimental results demonstrate the success of the proposed design.
A Study of Image Processing Based Object Depth Estimation
(2019-01-01)
Liaw, Der-Cherng
;
Zhao, Shao-Chun
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Hu, Yi-Ming
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電控工程研究所
;
Institute of Electrical and Control Engineering
Issue of object's depth estimation from binocular vision technique is studied in this paper. A binocular vision platform is set up to detect and estimate the object's depth. Mathematical derivation of object's depth from the two cameras of the proposed platform is re-visited to reveal the linkage between system parameters such as focal length and the estimation error. Both of simulation and experimental results are obtained for parametric analysis of estimation error. A comparison with Kinect is also given to demonstrate the superiority of the proposed design.
A Study of T-S Model-Based SMC Scheme With Application to Robot Control
(2008-11-01)
Liang, Yew-Wen
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Xu, Sheng-Dong
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Liaw, Der-Cherng
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Chen, Cheng-Chang
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電控工程研究所
In light of the remarkable benefits and numerous applications of the Takagi-Sugeno (T-S) fuzzy system modeling method and the sliding mode control (SMC) technique, this paper aims to study the design of robust controllers for a set of second-order systems using a combination of these two approaches. The combined scheme is shown to have the merits of both approaches. It alleviates not only the online computational burden by using the T-S fuzzy system model to approximate the original nonlinear one (since most of the system parameters of the T-S model can be computed offline) but also preserves the advantages of rapid response and robustness characteristic of the classic SMC schemes. Moreover, the combined scheme does not need to online compute any nonlinear term of the original dynamics, and the increase in the number of fuzzy rules does not create extra online computational burdens for the scheme. The proposed analytical results are also applied to the control of a two-link robot manipulator and compared with the results using classic SMC design. Simulation results demonstrate the benefits of the proposed scheme.
A TDMA Based Scheme for the Construction of R2R Communication Platform
(2014)
Liaw, Der-Cherng
;
Yeh, Chia-Wei
;
Lo, Sung-Ming
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電機工程學系
;
電控工程研究所
In the previous study (Liaw and Kuo, 2012), a preliminary version of the Time Division Multiple Access (TDMA)-based communication platform had been successfully tested to provide the function of wireless hopping data transmission. However, that design was only valid for the consecutive nodes which are close-by. A modified design was proposed in (Liaw, Wang and Lai, 2013) by using self-design Wireless Sensor Network (WSN) nodes to investigate the feasibility of the application in short range data communication. The effect of the packet size and distance between two consecutive nodes on the performance of remote data transmission was also studied. Instead, in this paper, we propose another scheme for time division wireless monitoring transmission protocol (TDWMTP). This design is based on IEEE 802.11a standard with the transmission method of TDMA (Time Division Multiple Access) to enhance and implement the function proposed in (Liaw, Wang and Lai, 2013). Experimental results demonstrate the success of the proposed design.
An approach to estimate domain of attraction for nonlinear control systems
(2006)
Liaw, Der-Cherng
;
Lee, Ching-Hung
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電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper we present the results of estimation of domain of attraction for nonlinear control systems. The theoretical results of [[9]] is modified and a computational methods to enlarge the domain of attraction for nonlinear control systems is proposed By the way, we have computational algorithms to estimate the attraction region for locally stable nonlinear systems in uncontrolled version. It is achieved by the construction of Lyapunov function for the nonlinear systems. Numerical results are given to demonstrate the applications.
Bifurcation Analysis of a Centrifugal Compressor
(2011)
Liaw, Der-Cherng
;
Chang, Shih-Tse
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents the local bifurcation analysis of the dynamic behavior for a centrifugal compressor. It is known that the surge phenomenon in compressor dynamics might occur at high pressure rise operation. Under such an operation, slight variation of the driving torque and/or the throttle opening might sharply reduce the compressor efficiency and even damage the system. Local bifurcation analysis of the centrifugal compressor system presented in this paper reveals the existence conditions of surge phenomenon. Bifurcation scenarios of compressor dynamics are also obtained with respect to the variation of driving torque and/or throttle opening, which provide a guide to determine the occurrence of nonlinear phenomena and reveal the stability limit for the compressor dynamics in the practical application. Numerical results demonstrate the linkage between nonlinear dynamical behavior and bifurcation phenomena.
Bifurcation analysis of boost converters with PWM IC
(2006)
Liaw, Der-Cherng
;
Song, Chau-Chung
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Zeng, Huo-Long
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電控工程研究所
;
Institute of Electrical and Control Engineering
The general boost converters designed by the commercial PWM IC are studied in,this paper. The commercial TLA94 IC is used to implement the PWM-controlled circuit. Applying the sampled-data approach, the mathematical model is constructed to analyze the nonlinear dynamics of the boost converter. The bifurcation theory is applied to study the stability and the nonlinear phenomena of the proposed model, while the system parameters of converters vary. Using the Matlab/Simulink software, the numerical simulation is performed to analyze the system behaviour and time responses merged from bifurcation points. Moreover, the bifurcation phenomena are demonstrated by implementing the experiments of the practical circuit. The understanding of nonlinear dynamics opens up new possibilities of operating regimes that can help to optimize the design of boost converters.
Common stabilizers for linear control systems in the presence of actuators outage
(2006-06-15)
Liang, Yew-Wen
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Liaw, Der-Cherng
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電控工程研究所
;
Institute of Electrical and Control Engineering
Issue concerning the existence of common stabilizers for a linear control system experiences actuators. outage are presented. The possible outage of actuators examined in this study are not restricted to a pre-specified set. By finding Common quadratic-type Lyapunov functions. we obtain sufficient conditions for the existence of common stabilizers. For cases of which all the possible failed actuators belonged to a pre-specified set. the results presented in this paper agree with those obtained by Veillette in 1995. The control gain of common stabilizer for non-nested case is explicitly derived to guarantee system stability. A simplified checking condition for the existence of common stabilizers is also obtained for the extreme case when only single actuator can normally operate. (c) 2005 Elsevier Inc. All rights reserved.
CONTINUOUS- AND DISCRETE-TIME FIXED-GAIN CONTROLLER DESIGNS FOR THE CONTROL OF VEHICLE LATERAL DYNAMICS
(2012-03-01)
Hsieh, Chien-Shu
;
Liaw, Der-Cherng
;
電機工程學系
;
Department of Electrical and Computer Engineering
In this paper, fixed-gain feedback linearization controls are presented to stabilize the vehicle lateral dynamics at bifurcation points for both continuous-time and discrete-time cases. Based on the assumption of constant driving speed, a second-order nonlinear lateral dynamics model is adopted for controller design. Via the feedback linearization scheme and the first-order Taylor series expansion, a time-invariant feedback linearization control is proposed as a fixed-gain linear version of the previously proposed nonlinear one. Furthermore, the conventional linear quadratic regulator (LQR) design is applied to facilitate the choice of the fixed-gain matrix. Refined controls to compensate the model uncertainty and their local stability analysis are provided. Extension of the continuous-time design results to discrete-time cases is also addressed. Numerical simulations for an example model demonstrate the effectiveness of the proposed continuous-time and discrete-time design results.
Control design for longitudinal flight dynamics
(2006)
Liaw, Der-Cherng
;
Chung, Wen-Ching
;
Hsieh, Chien-Shu
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, the control issues of longitudinal flight dynamics is presented. System controllability with respect to the variation of the elevator deflection angle is first discussed Stabilization controllers using washout filter-aided feedback control law is then proposed Case study for F-8 aircraft is explicitly derived for constructing a feasible set of controllers. Numerical simulations for bifurcation scenarios are also given to compare the performance of the designs.
Design of Midcourse Guidance Laws via a Combination of Fuzzy and SMC Approaches
(2010-04-01)
Chen, Chun-Hone
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Liang, Yew-Wen
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Liaw, Der-Cherng
;
Chang, Shih-Tse
;
Xu, Sheng-Dong
Issues regarding the design of midcourse guidance laws for antimissiles are addressed. The antimissile is expected to be guided to a place with a desired direction, where a ballistic missile is predicted to pass in the reverse direction, so that the target can be easily found and locked for terminal interception. The predicted location and direction of a ballistic missile may vary with time, due to information update using a trajectory prediction algorithm. To fulfill the guidance performance, the guidance laws are designed by combining the Takagi-Sugeno (T-S) fuzzy approach and the Sliding Mode Control (SMC) technique. Under the designed guidance law, it is shown that the antimissile is able to be efficiently guided to a specified location and direction, even when the existence of uncertainties and disturbances.
Design of Robustly Asymptotic Stabilizer Using a Time-Varying Sigmoid-Type SMC Scheme
(2008)
Liang, Yew-Wen
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Xu, Sheng-Dong
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Cheng, Chiz-Chung
;
Liaw, Der-Cherng
;
電控工程研究所
This study presents a class of first-order sliding mode stabilizing control laws, which preserve the advantages of rapid response and robustness from the conventional sliding mode control (SMC) schemes. The presented SMC laws are continuous everywhere so that the chaffering characteristic of the sign-type SMC laws is greatly alleviated. This scheme is also shown to be able to mend the saturation-type SMC's weakness of only achieving uniformly ultimate boundedness performance to an asymptotic stability level.