Control Strategies of Multichannel Functional Electrical Stimulation for Foot Drop Rehabilitation: A Review

This review systematically examines recent advances in the treatment of foot drop, with a particular focus on the integrated application of Functional Electrical Stimulation (FES) in intelligent rehabilitation. In recent years, FES has been widely applied in gait rehabilitation for patients with stroke, multiple sclerosis, and spinal cord injury by electrically stimulating target muscle groups to assist ankle dorsiflexion recovery. Compared to conventional single-channel systems, multi-channel FES (MFES) employs electrode arrays to synchronously regulate synergistic muscles across the hip, knee, and ankle joints (e.g., tibialis anterior, peroneus longus), combined with advanced control strategies that significantly improve walking speed (by 20%–90%) and muscle synergy similarity. This review systematically analyzes three mainstream control strategies in MFES systems—timing control, adaptive control, and iterative learning control (ILC)—exploring their mechanisms, application scenarios, and limitations. Building on this, we propose a hybrid control architecture integrating all three strategies via modular design: (1) a timing control module to maintain basic gait rhythm; (2) an adaptive module for rapid responses to individual differences (<50 ms); and (3) an iterative module to optimize long-term control using historical data (reducing hardware cost by 25%). This architecture effectively enhances the generalizability and control precision of MFES systems in complex rehabilitation scenarios. Future research may incorporate brain signal decoding techniques or develop few-shot adaptive algorithms based on meta-learning, advancing FES toward neuroplasticity-oriented precision rehabilitation.