Simulation Framework to Estimate Musculoskeletal Effects of Disruptive Design Changes in Human–Machine Systems

Assistive human–machine systems such as exoskeletons can reduce muscular effort and joint loading, but their effectiveness depends on design and control choices, such as the timing and shape of actuation forces. While many variants are conceivable, evaluating them experimentally typically requires prototypes and subject studies, which is time- and resource-intensive. A systematic, resource-efficient method is needed to compare candidate design/control variants early with respect to user strain. We present an OpenSim-based simulation framework to estimate musculoskeletal effects (e.g., muscle activations and joint moments) of disruptive design/control changes by combining experimentally measured motion and external loads with parameterized technical-system inputs for inverse dynamics and static optimization. The framework is discussed against three criteria: (1) suitability to study design/control changes systematically, (2) suitability to study design/control changes early and resource-efficiently, and (3) plausibility of predicted biomechanical trends. For that, we demonstrate the workflow on ankle exoskeleton–assisted gait and vary the actuation force magnitude. ... mehrThe simulations enable qualitative trend analysis (e.g., higher actuation forces reduce plantarflexor activation), supporting rapid control variant ranking and early-stage assessment. Quantitative accuracy is limited by prescribed kinematics/ground-reaction forces and other modeling assumptions. Nevertheless, the framework provides fast screening and optimization of design and control parameters with insight into muscle and joint loading.