Recent Advances in Mechatronics
The word mechatronics was first coined by a senior engineer of a Japanese company; Yaskawa, in 1969, as a combination of "mecha" of mechanisms and "tronics" of electronics and the company was granted the trademark rights on the word in 1971 [1-2]. The word soon received broad acceptance in industry and, in order to allow its free use, Yaskawa elected to abandon its rights on the word in 1982 . The word has taken a wider meaning since then and is now widely being used as a technical jargon to describe a philosophy in engineering technology, more than the technology itself. For this wider concept of mechatronics, a number of definitions has been proposed in the literature, differing in the particular characteristics that the definition is intended to emphasize. The most commonly used one emphasizes synergy: Mechatronics is the synergistic integration of mechanical engineering with electronics and intelligent computer control in the design and manufacture of products and processes.
The development of mechatronics has gone through three stages. The first stage corresponds to the years around the introduction of the word. During this stage, technologies used in mechatronics systems developed rather independently of each other and individually. With the start of the eighties, a synergistic integration of different technologies started taking place, the notable example being in optoelectronics (i.e. an integration of optics and electronics). The concept of hardware/software co-design also started in these years. The third and the last stage can also be considered as the start of the mechatronics age  and starts with the early nineties. The most notable aspect of the third stage is the increased use computational intelligence in mechatronic products and systems. It is due to this development that we can now talk about Machine Intelligence Quotient (MIQ). Another important development in the third stage is the possibility of miniaturization of the components; in the form of microactuators and microsensors (i.e. micromechatronics).
Fig. 1. The architecture of a mechatronic system
A mechatronics system has two main components as shown in Fig. 1. The controlled system is the mechanical process that is in contact with the world with all of its sensors and actuators. The distinguishing features of a mechatronic system from other systems are the three sub-systems of the controlling system used for perception, knowledge representation and planning and control. The intelligence is usually embedded in the planning and control sub-system. Here, based on the information gathered from the sensors, computational intelligence methodologies are exploited to plan a course of action that will enable the controlled system to achieve the given tasks. Conventional microprocessors, artificial neural networks, fuzzy logic and probabilistic reasoning are among the tools used in the sub-system for information processing and decision making.
Fig. 2. The functional diagram of semiosis
Fig. 2. The six-box diagram of behaviour formation
More recently, still a wider concept, concept of "semiotics" has been proposed as a new paradigm of science in the 21st Century . It is defined as a theoretical field which analyzes and develops formal tools of knowledge acquisition, representation, organization, generation and enhancement, communication and utilization. The functional representation of semiotics given in Fig. 2 (taken from ), is a different (and a more descriptive) form of Fig.1 and therefore displays the interrelation between semiotics and mechatronics. The same figure, when drawn as a six box diagram given in Fig. 3 can be used to describe the behavior formation in both living creatures and mechatronic systems. In each box of Fig. 3, the same six-box diagram can be placed, indicating a multiresolutional hierarchy .
The field of mechatronics is now widely recognized in all parts of world. Various undergraduate and graduate degree programs on mechatronic engineering are being offered at different universities. Journals dedicated to the field of mechatronics are being published, dedicated conferences are being held. One such conference is the one organized in Turkey during August 14-16, 1995, with the title, "International Conference on Recent Advances in Mechatronics : ICRAM'95", under the technical co-operation of ASME (American Society of Mechanical Engineers), IEEE (Institute of Electrical and Electronics Engineers) Industrial Electronics Society, IEEE Robotics and Automation Society, IEEJ (Institute of Electrical Engineers of Japan) , IFAC (International Federation of Automatic Control), IFToMM (Int. Fed. for the Theory of Machines and Mechanisms), JSME (Japanese Society of Mechanical Engineers), RSJ (Robotics Society of Japan) and SICE (Society of Instr. and Control Engineers of Japan). It had more than 200 participants from 34 different countries. This special issue has 10 papers selected out of the papers that were presented during this conference. During the selection process, attention was focused not only on quality but also on ensuring a good coverage of the mechatronics area, both from theoretical and experimental points of view. It should be pointed out that the papers are not exactly the same as they have appeared in the proceedings of the conference  as the authors have had the opportunity to update and expand their papers.
The first paper of the issue is a tutorial type of paper on the information processing for mechatronic systems. It discusses the mutual interrelations between mechanical and electronic designs and how to integrate them within a mechatronic system. The second paper is again of a tutorial type, discussing the concept of mechatronics design and its status in the world today. The third paper is more application oriented and describes several methodologies for the design of robust digital motion controllers and some application examples are given. The fourth paper of the issue focuses on assembly processes with robotic systems and gives a survey of the problems that are encountered in such cases and the solutions proposed. The fifth paper considers large and heavy manipulators as those used in building industry, agriculture, forestry and mining. In such applications, the environment is rough and unstructured and the manipulator is required to operate autonomously or operator assisted under rapidly changing working conditions. The paper considers the modeling, simulation and control design of three different large and heavy manipulators. The following paper also considers large structures in the form of human power amplifiers and describes the technology reached in this respect at University of California, Berkeley, USA. The original paper presented in ICRAM had the title "Robotic Systems Worn by Humans".
The next two papers consider different type of mechatronic devices. The first one is on the emerging topic of piezomotors which use piezoelectric instead of electromagnetic driving mechanisms. The paper describes the operational principles, design, construction and some operating characteristics of two prototypes, one being like a harmonic gear and the other is based on a roller clutch mechanism. The second paper addresses itself to reconstruction of hearing and describes a mechatronic implant for this purpose.
The last two papers of the issue are control oriented, the first one proposes a new method for the hybrid force/position control of an industrial robot which is equipped with an internal, high bandwidth velocity controller and with a compliant end effector. The second one, which is the last paper of the issue, again proposes a new approach for the control of robotic manipulators, combining fuzzy control with sliding mode control concepts. Experimental results obtained on a direct drive robot are presented.
I would like to take this opportunity to thank all the authors of this special issue for their valuable contributions. I hope that the readers of the issue will find the papers interesting and beneficial as much as I have done. I have certainly benefited a lot during the course of editing this issue. Thanks are also due to Profs. F.C.A. Groen and T.C. Henderson, the Editors-in-Chief of the journal and Dr. Y. Campfens, the Publishing Editor, for their continual support, encouragement and patience.
Bogazici University, Istanbul, Turkey
. Japan Trade Mark Kohhoku, Class 9, Shou 46-32713, 46-32714, Jan. 1971.
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