Theoretical Design and Modeling of a Novel Composite Flexible Mechanism

To enhance the comprehensive performance of flexible motion platforms in terms of precise positioning and large displacement amplification, this paper designs and investigates a novel composite mechanism that combines a rhombic amplification mechanism with a parallelogram-based flexible structure. Based on the Euler-Bernoulli beam theory and Castiglianos second theorem, the displacement amplification ratio and stiffness analytical model of the rhombic flexible mechanism are derived, and the Lagrangian equation is employed to establish an analytical model for the natural frequency of the flexible mechanism. Additionally, an analytical stiffness model for a single parallelogram is developed. Finite element analysis is then used to simulate the dynamic performance of the mechanism, verifying the rhombic amplification ratio, overall stiffness, and natural frequency. The results indicate that the designed composite mechanism achieves a high displacement amplification ratio, with a fundamental resonance frequency reaching 652 Hz, while maintaining high positioning accuracy and stability in two-dimensional motion. This meets the demands for high-precision and long-travel applications in flexible motion platforms. The findings provide innovative design ideas for applications in micro-nano manipulation, precision positioning platforms, and flexible sensors.