Development of Pneumatic-Based Exoskeleton System for Ankle Dorsiflexion and Plantarflexion

Mobility impairments particularly in ankle dorsiflexion and plantarflexion can significantly affect gait rhythm and quality of life. Despite various gait rehabilitation methods available to restore mobility and independence, current assistive devices used in gait rehabilitation offer limited support and adaptability, and lack IoT interfaces for real-time monitoring, creating a gap in effective and independent rehabilitation. This study aims to develop a pneumatic-based ankle exoskeleton that addresses these issues. This exoskeleton has features including specially designed pneumatic artificial muscles (PAMs) for effective actuation of ankle dorsiflexion and plantarflexion, an ESP32 microcontroller for processing, communication and control, solenoid valves for controlled air flow into the PAMs for controlled actuation and integrated sensors such as inertial measurement unit (IMU) and force-sensitive resistors (FSRs) for precise biomechanical assessments. The exoskeleton's mechanical frame is 3D-printed with PLA making it lightweight and portable. The exoskeleton is equipped with an MPU6050 IMU for ankle angle measurements, with its accuracy proven as it has a percentage difference of 7% in its angle readings with comparison to a digital goniometer. Four FSRs on its sole enables particular gait phase detection with the application of algorithms. The IoT user interface supported by Arduino IoT Cloud enables remote monitoring and control via a mobile app, allowing therapists to track and customise rehabilitation remotely. EMG analysis showed that walking with the exoskeleton reduced average RMS EMG signal amplitudes by 45.13% ± 36.12% for MG, 6.79% ±29.70% for LG, and 22.48% ± 49.35% for TA, indicating its effectiveness in reducing muscle activity and assist in ankle dorsiflexion and plantarflexion during gait. This proof of concept demonstrates the exoskeleton's potential to enhance gait rehabilitation and improve convenience for users and therapists.