Multimodal Gait Acquisition and Musculoskeletal Simulation for Subject-Specific Evaluation of Ankle Exosuit Cable Anchor Positioning in Cerebral Palsy

Wearable ankle exosuits require precise evaluation frameworks to optimize assistive force transmission and subject-specific configuration. This study presents a multimodal sensor-based experimental and computational framework to assess the influence of ankle exosuit cable anchor positioning on neuromuscular and energetic responses during gait in a child with spastic hemiplegic cerebral palsy. Three-dimensional kinematics were acquired using an optical motion capture system (12 infrared cameras), while ground reaction forces were recorded through instrumented force plates. Metabolic cost was experimentally measured using portable respiratory gas analysis. These sensor-derived data were integrated into a participant-scaled musculoskeletal model in OpenSim to simulate nine cable anchor configurations and quantify changes in muscle activation, force production, mechanical impulse, and metabolic power. Cable geometry altered the predicted distribution of plantar-flexor loading across configurations. Experimental measurements were not available for muscle-level outputs or for the assisted configurations; therefore, these responses were interpreted as model-derived, exploratory comparisons rather than experimentally validated physiological effects. Configurations with larger offsets from the heel-reference position tended to yield greater reductions in gastrocnemius demand, whereas configurations nearer the heel reference more effectively reduced soleus loading but increased secondary stabilizing muscle recruitment. Predicted metabolic changes across assisted configurations ranged from a $0.86\%$ reduction to a $6.28\%$ increase relative to the experimental baseline, and from a $2.66\%$ reduction to a $4.33\%$ increase relative to the simulated non-actuated condition. These differences should be interpreted as indicators of model sensitivity rather than demonstrated energetic improvements. This study demonstrates how multimodal gait sensing combined with musculoskeletal simulation provides a quantitative tool for preliminary screening of cable-driven ankle exosuit design in pathological gait.