ABSTRACT
The purpose of this chapter is to briefly expound on some basic notions that are useful in dealing with the subject of meso-and micro-actuators in a unitary manner. In addition, an additional and hidden purpose is pursued: to propose a coherent notation that accompanies the reader through the entire length of this monograph. Although these tasks seem apparently easy, various obstacles arise between us and our objectives. Regarding the possibility of realizing a unitary, clear, and concise synthesis, we observe that human limits and the knowledge of the author do not allow writing the last word on such a wide and complex subject. Furthermore, the author is interested in illustrating the theme emphasizing the functional characteristics of an actuator, that is, first, its ability to produce a movement and, second, its ability to generate a mechanical work. In this sense, the notions that are introduced in this chapter, except for kinematic and dynamic ones such as structural, electromagnetic, and thermal knowledge and others, are considered only to properly represent the kinematic and dynamic behavior of meso-and microactuators and to allow their description, design, or correct selection. In fact, in these types of machines, we can seldom discuss matters that are not strictly related to kinematics and dynamics because they are energy transformers, and the high degree of integration in their design involves different physical phenomena. These adjoined nonmechanical notions can only be briefly summarized because, if deeply treated, they would require a series of specialized treatises. Because of the interaction between different disciplines and with the cornerstone fields of kinematics and dynamics, the latter problem has to be faced. A simple solution can be expounding distinct notations in distinct chapters, but that does not allow acquisition of an overall view of the technical issues regarding meso-and micro-actuators; therefore, we also undertake this difficult task, avoiding an excessive discontinuity with standard nomenclatures that are widely analyzed and proposed by scientific and technical communities. Various authors have directed their research activities to the correct selection of a proper notation, and we cannot set aside the large number of works composed by many scientific societies and institutions; among different results, an interesting reference is the standard ISO 31, which represents a significant proposal on technical and scientific notations. The research teams that have been involved in interdisciplinary problems have usually achieved useful formulations; therefore, the notations proposed by developers of multiphysics analysis software can provide additional interesting references for selecting a proper notation. However, the indicated references should be considered only as sources of suggestions for our choices on
symbolism because we are driven by the necessity of adopting an approach that is suitable for properly describing the functional and design characteristics of a device from a kinematic and dynamic viewpoint and, additionally, an approach that considers interdisciplinary aspects of the proposed subject of this monograph. For this reason, the order of illustration of fundamental knowledge introduced in this chapter should be considered as a hierarchy to be respected also in the selection of a proper notation, with a penalization of the possible use of non-standard notation in non-mechanical disciplines.
