Development of a tilt-positioning mechanism driven by flextensional piezoelectric actuators

Abstract

Tilt-positioning mechanisms are required in optical systems for diverse applications. Compared to electromagnetic tilt-positioning mechanisms, piezoelectric tilters are superior with regard to high positioning resolution, cost-effectiveness, and no electromagnetic interference issues. But their applications are limited by small motion ranges. To overcome this problem, a novel piezoelectric tilt-positioning mechanism is proposed and developed in this paper, aiming to achieve a large output range in compact size. Serving this purpose, flextensional piezoelectric actuators (FPAs) are employed in this mechanism and their optimal structure is pursued. The existing approach to model and analyze the structure of FPAs is not perfect, making it challenging to exactly characterize and optimize actuator performance for its applications. To address this problem, a hybrid-body model of the FPAs is developed and based on this model, a governing equation is established to exactly and comprehensively characterize their kinematic performance. This equation allows the application requirement to be readily related to the actuator design, enabling the optimization of tilter design and the actuators. Using the optimized parameters, an experimental prototype is fabricated. This specimen achieved more than 15 mrad of angular travel at a small size of 35 × 42 × 42 mm, and the error between the analytical model and the experiment was less than 5%. These results support the accuracy of the hybrid-body model and indicate that the proposed tilter is very promising for practical applications.

Analysis and Optimization of Dynamic and Static Characteristics of the Compliant-Amplifying Mechanisms

“…Figure 4 a shows the relationship between the rhombus-type compliant mechanism’s amplification ratio and the bridge arm angle when the FEM results are compared with the MSTMM results. The figure shows that the two methods have similar trends, in that the amplification ratio increases initially and subsequently decreases with increasing bridge arm angle, which is consistent with the previous description in the literature [ 52 ]. Furthermore, the relative error between the two models decreases sharply as the angle increases, before gradually stabilizing after 15 .…”

“…Through a combination of analysis and comparison, it was found that the main cause of this phenomenon is the stress concentration effect in the connection area between the bridge arm of the compliant-amplifying mechanism and the rigid body unit (see Figure 9 a), which results in uneven distribution of the deformation [ 32 , 52 ]. In addition, this error also occurs because the FEM results that are used as reference values will be affected by the quality and size of the mesh.…”

Analysis and Optimization of Dynamic and Static Characteristics of Compliant Amplifying Mechanism

“…Figure 4a shows the relationship between the rhombus-type compliant mechanism's amplification ratio and the bridge arm angle when the FEM results are compared with the MSTMM results. The figure shows that the two methods have similar trends, in that the amplification ratio increases initially and subsequently decreases with increasing bridge arm angle, which is consistent with the previous description in the literature [52]. Furthermore, the relative error between the two models decreases sharply as the angle increases, before gradually stabilizing after 15 • .…”

Digital Demodulation Using I/Q Signals and Optical Phase Control Applied to a Vibrometer

“…In addition, AV J 0 (φ P ZT ) cos(φ L1 (nT S )) and AV J 0 (φ P ZT ) cos(φ L2 (nT S )) can also be expanded in series of Bessel functions of the first kind. Thus, taking into account (28) and (29), results:…”

“…MAFPAs consist of multi-flexible structures actuated by two or more piezoceramics, and thus, can provide more than one degree of freedom. This solution allows, for example, the development of nanopositioner XY stages [28], tilt-positioning mechanisms [29], piezoelectric grippers [30] and piezoelectric motors [31]. The MAFPA devices used in this paper were designed (using the topology optimization method) and manufactured utilizing two PZT piezoceramics, and therefore actuators with two degrees of freedom were obtained.…”