SYNTHESIS OF LARGE STROKE CONSTANT TORQUE MECHANISMS VIA ITERATIVE STRUCTURAL OPTIMIZATION AND NONSYMMETRIC DESIGN FOR ENHANCED STRAIN RELIEF

Compliant constant torque mechanisms (CTMs) offer a novel approach to maintain torque levels with their nonlinear torque rotation relation in a monolithic design. Current CTM designs have limited stroke (20-70 degrees) and coefficient of variance (COV) (±%). It is hypothesized that both complex geometry and ineffective compliant members together increase computational cost and reduce strain relief capacity. In this study, an iterative optimization approach to address ineffective members in CTMs is proposed, aiming to enhance stroke range while minimizing complexity. Leveraging design methods related to strain relief from constant force mechanisms (CFMs), our methodology employs the graph method with nodal perturbation to introduce more slenderness and tortuosity efficiently into the geometry. Through iterative optimization with FEA models for CTMs achieved extended stroke ranges of 20-130 and maintained COV to about ± 2, overcoming limitations of traditional CTMs. The experimental results show %0-120 stroke ranges and around ± 3 COV. This study offers a new methodology to efficiently design CTM while overcoming certain limitations existing in current methods. Such method may further be utilized in surgical and robotics applications.