Servo motor selection criterion for mechatronic applications

Modern mechatronic applications often involve complex motions, resulting in highly dynamic motor loads. The selection of an appropriate motor is based on the characteristics of the load, besides other technical, as well as economic, considerations. However, motor characteristics, such as rotor inertia, affect the motor load, which complicates the analysis. The selection criterion presented in this paper separates the motor characteristics from the load characteristics and its graphical representation facilitates the feasibility check of a certain drive and the comparison between different systems. In addition, it yields the range of possible transmission ratios. The method is illustrated with an industrial case study     

Ten years of mechatronic research and industrial applications in Finland

A mechatronics research program was carried out in Finland from 1987 to 1990 as a joint project between industry and research centers. The program stimulated cooperation between these partners and supported the companies' own R&D projects. It also encouraged individuals in companies, together with research centers, to contemplate future possibilities in an innovative, interdisciplinary way and in teams. This resulted in new product concepts, and new collaborative applied research activities and programs with new goals. This work has been continued in several new technology programs, especially in applications of learning and intelligent systems which will be carried out from 1995 to 1998. The rapid progress of technology gives continuously new possibilities to meet the needs of customers. Soft computing with a control of nonlinearities is the new wave in making dramatic improvements in product and process performances.     

Realizations of fractional-order PID loop-shaping controller for mechatronic applications

A novel procedure for the realization of a fractional-order PID loop-shaping controller, suitable for precision control of mechatronic systems, is introduced in this work. Exploiting appropriate tools, the controller function is approximated as a whole, leading to a simple form of integer-order approximation, when compared to the case where each intermediate part of the PID transfer function is approximated. This leads to a direct implementation, composed of conventional active and passive elements. Simulation and experimental results, derived from the OrCAD PSpice simulator and a Field-Programmable Analog Array respectively, verify the efficient functionality of the proposed implementation procedure.     

Optimal design of ball-screw driven servomechanisms through an integrated mechatronic approach

This paper proposes a novel model-based mechatronic approach for the design of ball-screw driven servomechanisms. The proposed technique is aimed at selecting the optimal combination of electric motor and ball-screw which minimizes the motor torque, while ensuring the achievement of the prescribed dynamic performances of the closed loop system. Such performances, as well as feasibility constraints related to the component characteristics, are translated in the method as bounds in the lead – diameter space. In particular, feasible torque and speed are the constraints posed by the motor; screw critical speed, ball critical speed, service life, buckling load are those due to the ball-screw, while the controlled system performances are included through the inertia ratio and the bandwidth requirements. To this purpose, the ball-screw non-ideal characteristics are represented through models with different complexity and are accounted for in the design. A straightforward graphical approach is formulated to trade off between the many conflicting requirements and to prevent both overly conservative and undersized design, while ensuring problem solvability.     

Pole selection of feedforward compensators considering bounded control input of industrial mechatronic systems

A new pole selection method for feedforward compensators of mechatronic servo systems is presented in this paper. It is necessary to have the system poles located at desirable positions on the s-plane in order to realize better servoing performance. However, selection of new poles is not a straightforward problem and in most industrial mechatronic systems, it has been a mere cut-and-dry procedure. In this research, feedforward compensator poles are related to the control input, and a criterion was developed to determine the desirable poles that improve the control input within its limits. This method was developed for the second-order model and it was simulated and experiments were performed with the Performer MK3s articulated industrial robot manipulator. Some attractive results have been obtained with the new method.     

Optimal selection of ARQ parameters in QAM channels

For a quadrature amplitude modulation (QAM) communication channel with forward error correction (FEC) and automatic repeat request (ARQ), the bit error rate (BER) is estimated as a function of the channel signal‐to‐noise ratio (SNR). A method is presented for trading off the number of allowed transmissions and the level of margin (or the line ARQ gain) applied to the channel SNR. The line ARQ gain maximizing the channel throughput is shown to be a sum of the channel SNR and some function of the bit load and FEC parameters. Using this result, we formulate a fast method of determining the optimum ARQ parameters at the actual channel conditions, based on their values at some reference conditions, the latter being either stored in the modem memory or pre‐calculated prior to channel initialization. The derivations are presented both for AWGN and slowly fading channel conditions. Copyright © 2004 John Wiley & Sons, Ltd.     

Investigation of mechatronic education in South Korea

This paper presents diverse aspects of South Korean mechatronic education in an effort to provide the basis of constructing a more desirable educational system on mechatronics. For this purpose, an analysis of the curriculum of 15 universities with departments of mechatronics are presented. It can be said that, in South Korea, characteristics of mechatronic education is that independent organizations for Mechatronics are operated over 15 universities and their curriculum is evolved to adapt local industrial environments. Almost all of them are trying to meet the requirements of Accreditation Board of Engineering Education of Korea (ABEEK), which is very similar to Accreditation Board of Engineering and Technology (ABET) in the United States. Another distinguishing feature is that the National Qualification Test for Mechatronics is offered in South Korea. The problem to be solved in near future is that there are some conflicts between ABEEK requirements and National Qualification Test. The ratio of students from vocational high schools entering 4-year universities is increasing in South Korea. The same tendency can be found in Japan, and some universities are trying to offer preparation courses to provide basic knowledge on physics, mathematics and chemistry to them.     

Optimal waveform selection for tracking systems

Investigates adaptive waveform selection schemes where selection is based on overall target tracking system performance. Optimal receiver assumptions allow the inclusion of transmitted waveform specification parameters in the tracking subsystem defining equations. The authors give explicit expressions for two one-step ahead optimization problems for a single target in white Gaussian noise when the tracker is a conventional Kalman filter. These problems may be solved to yield the most improvement possible in tracking performance for each new transmitted pulse. In cases where target motion is restricted to one dimension, closed-form solutions to the local (one step ahead) waveform optimization problem have been obtained. The optimal waveform selection algorithms in the paper may be included with conventional Kalman filtering equations to form an enhanced Kalman tracker. Simulation examples are presented to illustrate the potential of the waveform selection schemes for the optimal utilization of the capabilities of modern digital waveform generators, including multiple waveform classes. The extension of the basic waveform optimization scheme to more complex tracking scenarios is also discussed     

振荡器谐振回路的参数选择

针对振荡器谐振回路参数的选择较多地依赖于经验的问题,提出了从振荡器的等效电路出发,得到了描述振荡器的非线性微分方程,通过引入随机项来描述振荡器的内部电噪声,由此建立了用于分析振荡器行为的非线性随机微分方程。并针对遗传算法对振荡器谐振回路参数的优选结果,采用10MHz的Pierce晶体振荡器,得出了实证依据。当C1和C2比较接近时,Pierce振荡电路中的相位噪声可得到更好的抑止。     

Backlash fault detection in mechatronic system

In this paper, a fault detection and isolation model based method for backlash phenomenon is presented. The aim of this contribution is to be able to detect then distinguish the undesirable backlash from the useful one inside an electromechanical test bench. The dynamic model of the real system is derived, using the bond graph approach, motivated by the multi-energy domain of such mechatronic system. The innovation interest of the use of the bond graph tool, resides in the exploitation of one language representation for modelling and monitoring the system with presence of mechanical faults. Fault indicators are deduced from the analytical model and used to detect and isolate undesirable backlash fault, including the physical system. Simulation and experimental tests are done on electromechanical test bench which consists of a DC motor carrying a mechanical load, through a reducer part containing a backlash phenomenon.     

Optimal network selection in heterogeneous wireless multimedia networks

The complementary characteristics of different wireless networks make it attractive to integrate a wide range of radio access technologies. Most of previous work on integrating heterogeneous wireless networks concentrates on network layer quality of service (QoS), such as blocking probability and utilization, as design criteria. However, from a user’s point of view, application layer QoS, such as multimedia distortion, is an important issue. In this paper, we propose an optimal distributed network selection scheme in heterogeneous wireless networks considering multimedia application layer QoS. Specifically, we formulate the integrated network as a restless bandit system. With this stochastic optimization formulation, the optimal network selection policy is indexable, meaning that the network with the lowest index should be selected. The proposed scheme can be applicable to both tight coupling and loose coupling scenarios in the integration of heterogeneous wireless networks. Simulation results are presented to illustrate the performance of the proposed scheme.     

Modeling and design methodology for mechatronic systems

The integration of mechanical systems and microelectronics opens many new possibilities for process design and automatic functions. After discussing the mutual interrelations between the design of the mechanical system and digital electronic system the different ways of integration within mechatronic systems and the resulting properties are described. The information processing can be organized in multi levels, ranging from low level control through supervision to general process management. In connection with knowledge bases and inference mechanisms, intelligent control systems result. The design of control systems for mechanical systems is described, from modeling, identification to adaptive control for nonlinear systems. This is followed by solving supervision tasks with fault diagnosis. Then design tools for mechatronic systems are considered and examples of applications are given, like adaptive control of electromagnetic and pneumatic actuators, adaptive semiactive shock absorbers for vehicle suspension, and electronic drive-chain damping.     

Optimal design and applications for quasi-phase-matching three-wave mixing

Solutions of quasi-phase-matching three-wave mixing (TWM) for a nonuniform grating structure with phase-shifted segments are derived by use of a matrix operator, for the first time to the authors' knowledge, under the small-signal approximation. Compared with iterative methods of coupled-mode equations, using these expressions can significantly shorten the calculation time, and they can be effectively applied to all-optical signal processing in TWM. The signal and pump bandwidths of wavelength conversion in difference-frequency mixing, as well as the all-optical gating bandwidth in sum-frequency mixing, are optimized with the matrix solutions. By comparison with loss-free waveguide, the propagation loss a of the waveguide decreases the conversion efficiency /spl eta/, but has little influence on the bandwidth. Numerical results show that /spl alpha/ can be ignored for nonlinear lengths L<20 mm, and the optimal bandwidth /spl Delta//spl lambda/ is sensitive to /spl eta/ and the variation in the grating period, but not to /spl alpha/.     

Optimal vector control of pumping and ventilation induction motor drives

An original speed control for centrifugal pump and fan drives with squirrel-cage induction motors that seeks the maximum energy saving is proposed. The strategy is based on minimizing the motor and converter losses at the steady state and minimizing the transient time that the motor employs in passing from one steady stage to another. The shortest transient time is achieved by applying the Pontriagin's maximum principle taking into account the parabolic load torque-speed dependence of these types of drives. Short-time transients, which take the motor from one point of maximum efficiency to another, contribute to reduce losses and to extend the application of the energy-saving concept to the drives with frequent changes of load torque and speed.     

Flying capacitor multilevel inverters and DTC motor drive applications

In this paper, the requirements imposed by a direct torque control (DTC) strategy on multilevel inverters are analyzed. A control strategy is proposed in order to fulfill those requirements when a flying-capacitor multilevel inverter is used. Simulation and practical results will confirm the performance of the proposed strategy when using the multilevel inverter to control an induction motor by the DTC principle. Also, the advantages of using a multilevel inverter with a DTC strategy are shown by simulation results.     

小波变换在运动想象脑电分类中的应用

脑机接口技术是一项不依赖人的外周神经和肌肉组织而实现人机交互通信的技术,使人类可以拥有一条不通过肌肉组织与外界交流而实现人机通信及控制的通道。在总结前人研究成果的基础上,采用了小波变换Mallat算法对实验数据进行特征提取,重点研究了时间窗的选取和利用频率范围选取有用信号的问题。通过SVM的分类结果为准确率84.2856%,精密度85.2721%和灵敏度92.0006%。     

Optimal reliable relay selection in multiuser cooperative relaying networks

In this paper, we investigate the problem of optimal reliable relay selection in multiuser cooperative wireless networks in the presence of malicious relay nodes. A general discrete time queueing model for such networks is introduced which takes into account the dynamic variations of the channel state, the dynamic malicious behaviour of relay nodes as well as stochastic arrival of data packets into the system. The model consists of a set of mobile users, one destination node and a set of relay nodes which may be either mobile or fixed. The system uses the benefit of cooperative diversity by relaying in the decode and forward mode. We assume that each user either transmits its packets directly to the destination (direct mode) or transmits them with the cooperation of a selected relay node (cooperative mode). It is assumed that a centralized network controller manages the relay selection process in the system. At each time slot, a malicious relay node in the system may behave spitefully and refuse to cooperate with a user deliberately when it is selected to cooperate with that user. A malicious relay node usually acts stochastically to hide its malicious behaviour for longer time. In such a system, at each time slot the network controller should decide whether a user has to cooperate with any relay node or not and if so, which relay node must be selected for cooperation. First, we show that the malicious behaviour of relay nodes makes the stable throughput region shrink. Then, we propose a throughput optimal secure relay selection policy that can stabilize the system for all the arrival rate vectors strictly inside the network stability region. We show that the optimal policy is equivalent to finding the maximum weighted matching in a weighted bipartite graph at each time slot. Finally, we use simulations to compare the performance of the proposed policy with that of four other sub-optimal policies in terms of average queue occupancy (or queueing delay).     

隐身目标雷达散射截面最优分布模型选择

隐身目标严重削弱雷达探测威力,研究其雷达散射截面(Radar Cross Section,RCS)分布特性有助于评估雷达对隐身目标的检测性能,这是开展反隐身技术研究的基础.文中以F-117A为例,提出一套完整的选择隐身目标RCS最优分布模型的方法,该方法由获取RCS数据,分布特性拟合,拟合优度检验三部分组成.分别采用x2分布、对数正态分布、赖斯分布和非参数法模型拟合F-117A全向RCS数据,并进行x2拟合优度检验.结果表明该方法具有可行性,并可扩展用于研究其他型号的隐身目标.     

Integrating viewpoints in the development of mechatronic products

The development of mechatronic products involves multiple stakeholders which have different viewpoints and therefore use different concepts, models and tools to deal with their concerns of interest. This paper argues that an increased emphasis needs to be placed on the relations between viewpoints to be able to deal with the evolving scope and requirements on mechatronic products. We study relations between viewpoints at the levels of people, models and tools, and present solutions that are used to formally and explicitly capture such relations. Viewpoint contracts are used to define the vocabulary, assumptions and constraints required for ensuring smooth communication between stakeholders (people level). Dependency models capture relations between product properties belonging to different viewpoints, and how such dependencies relate to predictions and decisions (model level). Tool integration models describe the relations between tools in terms of traceability, data exchange, invocation and notifications (tool level). A major contribution of this paper is a unification approach, elaborating how these solutions can be used synergetically to integrate viewpoints. An industrial robot case study is utilized to illustrate the challenges and solutions with respect to relations between viewpoints, including the unification approach.