| The integration of sensor and actuator is essential demand of MEMS and smart materials and structures. Two integration patterns are summarized which are structural integration and functional integration. Functional integration can be termed as self-sensing actuator (SSA), in which a single element simultaneously functions as a sensor and an actuator. SSA has advantages in decreasing system volume and weight, saving space, true collocation and increasing stability.This paper studies the SSA made by simplex uniform material. This kind of SSA is a contribution to composite smart materials and structures and MEMS in sensor and actuator integration. The work includes the theory study and the application study.Piezoelectric and magnetostrictive materials are two typical bilateral materials that can be made into SSAs. Up to now the study on these two kinds of SSAs is mainly limited on the application and improvement of bridge-circuit based approach. This paper attempts to describe the theoretical model of SSA. Based on the theory of bilateral electromechanical transducer, SSA is modeled by transfer matrixes of bilateral transducers. This model can not only describe the electromechanical energy conversion laws of SSA, but also give a perfect explanation of existing bridge circuit based SSA approach and observer based SSA approach. After investigating the characteristic of the transfer matrixes of SSA, this paper predicts two possible SSA approaches of space-sharing and time-sharing, which will be most important to the design and further study of SSA if validated.Self-sensing actuator is firstly actuator and then sensor. Because the output of piezoelectric actuator has close relation to mechanical and electric boundary condition, this paper analyzes the relations between boundary condition and piezoelectric equation as well as hysteresis. The output force and displacement versus voltage of bimorph with inner thick electrode are derived, which provide the design basis for SSA under arbitrary boundary condition.Besides, this paper studies the bridge based and observer based self-sensing approaches and their applications. There are different application fields due to different decoupling approaches.Bridge based piezoelectric SSA adopts voltage driving. The current proportional to the strain rate can be drawn from driving voltage through a bridge circuit, so in most cases, the SSA realized by this method is suitable for dynamic application. A piezoelectric SSA is implemented basing on a strain rate bridge circuit in order to control the vibration of cantilever beam. Instrumentation amplifier and low-pass filter are designed to deal with the sensed weak signal. A simple controller consisting of high voltage amplifier 3583, proportional adjustment and phase lag compensation is designed in view of the bridge is slightly unbalanced. The experimental results show that bridge based SSA not only can be a vibration detector but also has good performance in vibration control of beam.Observer based SSA can act as not only actuator but also displacement sensor and forceHIsensor. The key issue is to get both voltage and charge of piezoelectric element, and then design strain and stress observer according to piezoelectric equations. Aiming the application at self-sensing piezoelectric gripper, driving method, hysteresis compensation and observer design are studied. The Generalized Maxwell Slip model is adopted to describe voltage versus charge relation and some modifications are made in order to fix model parameters using Least Mean Square. The model error and model predicting error are proved to be within 2.5%. After comparing the advantages and disadvantages of voltage driving and charge driving, the author proposes a programmable compound circuit to meet the demand of static application, which can voltage-drive piezoelectric actuator and get the resulting charge concurrently, and is a hardware platform for the observer based SSA approach. Based on the compound circuit, the driving voltage and charge of piezoelectric bimorph...
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