A Co-Simulation Platform For Closed-Loop Evaluation Of Human-Exoskeleton Control Strategies

Effective control of lower-limb exoskeletons depends on a comprehensive understanding of both human biomechanics and robotic actuation. We present a modular co-simulation framework that couples a physics-based exoskeleton model in Simscape with a musculoskeletal human model in OpenSim. The system supports bidirectional, stepwise interaction: joint angles from the exoskeleton model are sent to OpenSim, which returns corresponding interaction torques for use in the next simulation step. This closed-loop coupling enables the evaluation of assistive control strategies in a physiologically meaningful environment prior to hardware deployment. To demonstrate the framework's utility, we implement the adaptive Central Pattern Generator (CPG) strategy previously established in the literature as a representative case study. The results verify that the co-simulation environment successfully captures the intended closed-loop behavior, such as torque-dependent gait modulation and perturbation recovery. This confirms the platform's efficacy as a versatile tool for testing and refining human-exoskeleton interaction strategies before experimental trials.