Lego-Like Stiffness Configuration of Planar Compliant Modules for Task-Specific Flexible Interfaces

2026-10-05

AI Summary

This study addresses the challenge of rapidly customizing stiffness in compliant mechanisms due to geometric constraints and stiffness coupling. A Lego-like stackable planar compliant module design method is proposed, establishing a unified model through a novel modular stiffness configuration framework to achieve stiffness decoupling and flexible reconfiguration. The optimization employs a genetic algorithm for module configuration search combined with sequential quadratic programming for parameter refinement. Experimental results demonstrate that simulated stiffness deviations remain below 6.5%. Furthermore, a developed compliant wrist prototype achieves approximately 15° angular compliance alongside prescribed stiffness characteristics during high-speed motion, validating the effectiveness of the proposed approach.

Abstract

Compliant mechanisms provide compact and intrinsic structural compliance for regulating physical interactions between mechanisms and environments. However, different tasks demand distinct stiffness characteristics, often requiring task-specific optimization and redesign due to limited geometric design space and inherent coupling among multiple stiffness components. This paper presents a Lego-like stiffness configuration approach using stackable planar compliant modules. Three complementary module geometries are introduced, with their stiffness characteristics further regulated through beam width, plate thickness, and module orientation. A unified stiffness model is established for quantitative analysis of individual and composed modules. Further, a two-stage optimization method is presented to achieve desired stiffness profiles, combining a genetic algorithm for configuration and sequential quadratic programming for parameter refinement. Experimental verification shows deviations below 6.5% for simulated stiffness. A flexible wrist is further developed as a representative implementation, exhibiting distinct compliant and dynamic responses under different stiffness characteristics. An optimized modular composition realizes prescribed stiffness values and maintains compliant obstacle interaction during high-speed motion at 1 m/s, with a maximum tested angular compliance of approximately $15^\circ$. The proposed framework provides a systematic approach for constructing flexible interfaces with task-specific stiffness characteristics.

Problem

• compliant mechanisms
• stiffness configuration
• task-specific stiffness
• modular design
• flexible interfaces

Innovation

• Compliant mechanisms
• Stiffness configuration
• Modular design
• Two-stage optimization
• Flexible interfaces