A 2-DoF Ankle Rehabilitation Platform Based on an Inclined Dual-Cylinder Mechanism
Donggeon Kim, Kira Kiefer, Luisa Veits, Laura Ulbl, Necolle Morgado-Vega, Tae-Hyoung Kim, Yeongmi Kim
Abstract
This paper presents a novel ankle rehabilitation platform based on an inclined dual-cylinder mechanism that provides 2-DoF motion through geometric coupling, without complex multi-link structures. Two cylinders sharing a 9° inclined contact surface are driven by two stepper motors, enabling simultaneous dorsiflexion/plantarflexion and inver sion/eversion of up to 18° in each axis. The platform provides both a passive mode, which follows predefined trajectories, and an active mode, which captures user intent through center-of pressure estimation using a force-sensing resistor–based insole. A Particle Swarm Optimization–tuned PD controller is used in both modes, achieving an RMS tracking error below 0.35°in experimental validation. An IMU-integrated gamification environment further demonstrates the feasibility of the platform as an interactive active training system.