Abstract
<title>Abstract</title> <p>Industrial robotic manipulators face a persistent trade-off between structural mass, stiffness, and positioning precision. Conventional designs rely on solid metallic links that achieve high rigidity at the expense of increased inertia, which limits dynamic performance and energy efficiency. This study proposes a novel robotic arm architecture that integrates bio-inspired morphology, topology-optimized lattice structures, and adaptive variable-stiffness joints within an AI-assisted generative design framework. The proposed architecture draws structural principles from the elephant trunk and human forearm, combining a segmented continuum-inspired outer profile with rigid precision bearing interfaces at each joint. Internal lattice reinforcement employs triply periodic minimal surface (TPMS) gyroid unit cells with spatially graded relative density, determined through homogenization-based multiscale optimization. Variable-stiffness joints utilize discrete layer-jamming mechanisms integrated at each articulation interface, enabling stiffness modulation ratios exceeding 17:1 under applied clamp pressures up to 3 MPa. A diffusion-model-based AI design framework generates candidate topology distributions, which are subsequently verified through solid isotropic material with penalization (SIMP) compliance minimization and nonlinear finite element analysis. Numerical simulations demonstrate that the proposed architecture achieves a mass reduction of approximately 41% relative to a solid baseline while maintaining maximum von Mises stress below 280 MPa and end-effector deflection below 0.05 mm under a 25 kg payload. Modal analysis reveals a first natural frequency of 42.6 Hz in the high-stiffness configuration, compared with 18.3 Hz in the compliant state. The variable-stiffness capability allows the arm to operate in a high-compliance mode during approach trajectories and transition to a high-rigidity state for precision positioning, reducing settling time by an estimated 37%. Manufacturing feasibility is evaluated through selective laser melting (SLM) process simulation for Ti-6Al-4V lattice links, with design-for-additive-manufacturing constraints applied to overhang angles, minimum strut diameters, and support structure generation. Performance benchmarks against the FANUC M-20iD/25, Universal Robots UR10e, and ABB IRB 6700 confirm that the proposed architecture remains competitive in payload capacity and repeatability while offering superior mass-specific stiffness. The findings establish a validated design methodology for next-generation industrial manipulators that combine biological design principles with computational structural optimization and adaptive stiffness control.</p>