Topology Optimization of a Robotic Manipulator Link: A SIMP-based Design, Simulation, and Trade-off Study

Abstract

Robotic manipulator links are prime candidates for topology optimization as they carry well-defined end loads, connect through discrete pin joints, and their mass directly drives actuator sizing, energy consumption, and dynamic performance. This paper presents a density-based (SIMP) topology optimization case study of a two-pin robotic link subjected to a representative end-effector load, formulated as compliance minimization under a volume-fraction constraint. The study describes the design-domain setup, boundary conditions, and finite-element-based sensitivity framework, then reports the iterative evolution of the pseudo-density field from a solid initial guess to a converged, truss-like final topology. The optimized link achieves a 58% mass reduction relative to a solid baseline while increasing specific stiffness (stiffness-to-mass ratio) by over 100%, at the cost of an 18% increase in absolute compliance and a modest 9% reduction in first natural frequency, trade-offs that remain within typical robotic-arm design margins. It further examines the mass–compliance Pareto front across a range of volume-fraction constraints, compares simulated stress distributions between the solid and optimized designs, and discusses manufacturing considerations for realizing such geometries via metal additive manufacturing (AM), including overhang angles, minimum feature size, and post-processing needs. The results reinforce topology optimization as a practical, high-leverage tool for lightweighting robotic structural components without compromising structural safety margins.