A Self-Organizing Fuzzy Controller for the Active Vibration Control of a Smart Truss Structure

Abstract

In the last two decades, the subject area of smart/intelligent materials and structures has experienced tremendous growth in terms of research and development. One reason for this activity is that it may be possible to create certain types of structures and systems capable of adapting to or correcting for changing operating conditions. The advantage of incorporating these special types of materials into the structure is that the sensing and actuating mechanism becomes part of the structure by sensing and actuating strains directly. Piezoelectric material is often suitable for this purpose. This type of material possesses direct and converse piezoelectric effects; when a mechanical force is applied to the piezoelectric material, an electric voltage or change is generated, and when an electric field is applied to the material, a mechanical force is induced. With the recent advances in piezoelectric technology, it has been shown that the piezoelectric actuators based on the converse piezoelectric effect can offer excellent potential for active vibration control techniques, especially for vibration suppression or isolation. A truss structure is one of the most commonly used structures in aerospace and civil engineering (Yan & Yam, 2002). Because it is desirable to use the minimum amount of material for construction, trusses are becoming lighter and more flexible which means they are more susceptible to vibration. Passive damping is not a preferred vibration control solution because it adds weight to the system, so it is of interest to study the active control of such a structure. A convenient way of controlling a truss structure is to incorporate a piezoelectric stack actuator into one of the truss members (Anthony & Elliot, 2005). An important feature of control system in the truss structure is the collocation between the actuator and the sensor. An actuator/sensor pair is collocated if it is physically located at the same place and energetically conjugated, such as force and displacement or velocity, or torque and angle. The properties of collocated systems are remarkable; in particular, the