In many applications, a flexure hinge mechanism has often been used to amplify the displacement of a commercial multilayer piezoelectric actuator, in other words, piezostack because piezostacks have a limited deformation range of about 10 μms per centimeter. In this thesis, a new piezoelectric actuator using a bridge-type flexure hinge mechanism is developed and optimized. The mechanism consists of two bridge mechanisms, which are connected vertically in three-dimensional space and it has a symmetric structure which reduces negative effects due to temperature change. Because the developed hinge mechanism has three-dimensional structure, it has a high amplification ratio in a relatively small size. Generally, a simple lever rule can be used to estimate the amplification ratio of a hinge mechanism. The lever rule is very straightforward, but shows large errors in real systems, a factor of 10 in this example. Although FEM(Finite Element Method) software gives almost the same results as a real system, it requires an elaborate and time-consuming analysis procedure. In this study, the developed mechanisms are modeled by matrix methods assuming flexure hinges as 6 degree-of-freedom spring elements to show the validity of the proposed hinge mechanism. To verify the derived matrix model, displacement and frequency experiments are performed. The experimental result shows that the displacement error between the matrix model and experiments is below 10 percent when all other parts except hinges are sufficiently thick. This indicates that the deformation of the hinge in the parasitic direction should be considered for more exact estimation of the output displacement of the bridge-type hinge mechanism. To understand the general trend of the developed mechanism, the maximum efficiency, blocked force, and fundamental frequency are optimized with respect to the change of the output displacement using the developed matrix model. Experiments result show that the output displacement at 100 Volts is about 350 μms in size of 45×45×30㎣ and about 150㎛ in size of 30×30×15㎣. The developed hinge mechanism are to be used as a nano-gripper actuator which should be operated in small chamber such as SEM(Scanning Electron Microscope) chamber, so miniaturization of hinge mechanism is very important. To reduce the size of the developed hinge mechanism, geometrical nonlinear analysis and link deformation analysis are performed. When the total size of the bridge-type hinge mechanism is small compared to the deformation range of the hinge mechanism, the geometrical nonlinearity makes a considerable error in the output displacement. In this research, the incremental method based on the matrix model is developed to analyze the effect of the geometrical nonlinearity. The analysis and experiment results show that the geometrical nonlinearity error is about 10 percent of the moving range, so it should be considered in high-precision application. To analyze the link deformation problem, which is impossible using matrix model and essential for miniaturization of the mechanism, matrix displacement method is used. Analysis results shows that when the link thickness is smaller than 10 mm, the matrix model shows significant error and matrix displacement method is needed.
