GLOBE: Global Topological Exploration for Large-Displacement Compliant Constant-Force Mechanism Synthesis

Abstract

Abstract. Conventional methods for synthesizing large-displacement compliant constant-force mechanisms (CCFMs) are limited by approaches that fix a single topology and apply local refinements, which restricts the displacement range and increases force variation. To address these limitations, we propose the global topological exploration (GLOBE) method, a systematic approach that investigates a mechanism’s global beam-path topology to identify topologies with enhanced performance. This topology-first approach is supported by a theoretical model that establishes a direct analytical link between global topological parameters, such as aspect ratio (AR) and number of turns (Nt), and the resulting bending compliance, which in turn determines the amplitude of the nearly zero-stiffness region. A multistart depth-first search (MS-DFS) algorithm first generates a comprehensive database of unique beam paths. These candidates then undergo high-throughput computational screening (HTCS) via nonlinear finite-element analysis (NL-FEM) to evaluate their performance against six dimensionless metrics. Experimental validation of a selected triangular topology confirmed a nondimensional displacement of 0.60. This was achieved with only a 2.69% force variation, closely matching computational predictions. The GLOBE method demonstrates that systematic exploration of global topology is essential for synthesizing large-displacement CCFMs suitable for applications in robotics, medical devices, and aerospace.