Papers by Keyword: Piezo Actuator

Abstract: The main objective of this investigation is to improve the tracking accuracy of a piezo-actuated positioning stage using an iterative learning control. First, to compensate for the tracking error of the piezo-actuated positioning stage that is caused by nonlinear hysteresis, the dynamics of the hysteresis is modeled using the Bouc-Wen model. The particle swarm optimization (PSO) is used to determine the parameters of the inverse-hysteresis model. Second, the design of an iterative learning control is presented. Based on the simulation, the appropriate value of the learning rate is determined. Finally, the efficacy of the approach is demonstrated to achieve high accuracy positioning via the real-time experiments. The experimental result of the piezo-actuated positioning stage is measured by the laser interferometer (HP-5529A). The experimental results show that the iterative learning control can compensate the hysteresis-caused tracking error and the positional accuracy of better than 100 nano-meter is readily achieved.

Abstract: The displacement amplification and hysteresis of parallel four-bar mechanism using piezo actuator were researched in this paper. The displacement amplification was analyzed by employing the material bending theory firstly. Theoretical and FEM analysis proved that the amplification ratio of parallel four-bar mechanism is only related to the position of driving point and the guiding arm displacement is directly proportional to the input with the certain structure. Then the Preisach model was employed to model the hysteresis of guiding arm and using the model to perform the research on the output displacement of the mechanism. Experiments proved that the analysis is correct and showed that this model can effectively improve the accurate of the guiding arm output displacement and can realize output arbitrary series displacement using the Preisach interpolation surface.

Abstract: This paper researched the displacement amplification and hysteresis of parallel four-bar amplification mechanism using piezo actuator. Firstly, the displacement amplification was analyzed by employing the material bending theory. Theory and finite element model (FEM) proved that the amplification ratio of parallel four-bar mechanism is only related to the position of driving point and the guiding beam displacement is linear with the driving point input when it is fixed. Then the Preisach model was employed to model the hysteresis of guiding beam and performed to control the output displacement of the mechanism. Experiments proved that the model can effectively improve the output displacement accurate of the guiding beam and can realize random sequence output displacement using the Preisach interpolation surface.

Abstract: The fracture of mechanically loaded ceramics is a consequence of material critical defects located either within the bulk or at the surface, resulting from the processing and/or machining and handling procedures. The size and type of these defects determine the mechanical strength of the specimens, yielding a statistically variable strength and brittle fracture which limits their use for load-bearing applications. In recent years the attempt to design bio-inspired multilayer ceramics has been proposed as an alternative choice for the design of structural components with improved fracture toughness (e.g. through energy release mechanisms such as crack branching or crack deflection) and mechanical reliability (i.e. flaw tolerant materials). This approach could be extended to complex multilayer engineering components such as piezoelectric actuators or LTCCs (consisting of an interdigitated layered structure of ceramic layers and thin metal electrodes) in order to enhance their performance functionality as well as ensuring mechanical reliability. In this work the fracture mechanisms in several structural and functional multilayer components are investigated in order to understand the role of the microstructure and layered architecture (e.g. metal-ceramic or ceramic-ceramic) on their mechanical behaviour. Design guidelines based on experiments and theoretical approaches are given aiming to enhance the reliability of multilayer components.

Abstract: The modeling and compensation of hysteresis in piezoelectrically driven systems are very important for positioning and noise and vibration reduction applications. An active vacuum clamping system for a stationary wood machining center with piezo actuators for the purpose of vibration control has been developed. This active system is intended to reduce workpiece vibrations, which are excited during machining. However, the piezo actuators have an inherent hysteresis effect between input voltage and output position of the vacuum plate. The Bouc-Wen and the Classical Preisach methods are studied in this paper to model the hysteresis curves and to compensate the hysteresis effect of the integrated piezo actuator.

Abstract: The electro-mechanical (E/M) impedance-based method is one important and effective method in damage detection. The basic concept of the impedance method is to monitor the variations in the structural mechanical impedance spectrum caused by damage in the structure. Comparing the impedance spectrum to a baseline measurement of the undamaged structure, the real part of the E/M impedance reflects the state of structural health in the local area, therefore, the structural damage can be localized, a local-area self-sensing method is implemented. In this paper, an aluminium plate mounted on an electromagnetic shaker is used to detect growing fatigue damage using the impedance method. The growing damage is documented by an increase of the indicators. For the case of a static artificial damage the concept is also demonstrated to an Airbus A320 fuselage part using 9 self-sensing elements on the stringers.