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

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.