Plantar Compensation Via Dynamic Control of Pneumatic Insoles for Flatfoot Deformity
Bin Zhang, Yan Guo, Yijun Zhang, Jingang Yi, Binrui Wang, Tao Liu, WENYANG LI, Long He
AI summary
Problem
Current orthotic devices are largely passive and fixed-shape, failing to replicate the foot’s natural lock-unlock mechanism and often causing muscle dependency in flatfoot patients.
Approach
The team developed a soft pneumatic insole with synchronized airbags and implemented a Model Predictive Control strategy to dynamically adjust arch support throughout the gait cycle.
Key results
- Improved normalized navicular height index by 0.014 in flatfoot patients
- Reduced calf muscle activity (FL, SOL, GAST) by up to 23.84% during stance phase
- Achieved reliable pneumatic pressure tracking with a 0 to 1.5 Hz operational bandwidth
- Effectively decreased posterior muscle fatigue as measured by median frequency shifts
Why it matters
This dynamic support system offers a clinically viable alternative to static orthotics, advancing wearable robotics for targeted flatfoot rehabilitation and muscle function restoration.
Abstract
Human feet are crucial for supporting body weight and adapting to complex terrains. Adult-acquired flatfoot defor- mity (AAFD) arises from congenital or acquired causes, impair- ing the foot’s ability to transition between flexible and rigid states, known as the lock-unlock mechanism during the stance and swing phases. In this study, we propose a plantar dynamic support system that utilizes pneumatic airbags, regulated through a model predictive control (MPC) strategy to minimize tracking errors. Experiments were conducted to measure kinetic parameters and electromyography signals, validating the system’s efficacy. The results showed improvements in the normalized navicular height truncated (NNHt) index and reductions in muscle activity of the fibularis longus (FL), soleus (SOL), and gastrocnemius (GAST) by 4.42%, 16.65%, and 23.84%, respectively, during the stance phase.