Impedance Control for Ankle Preparation Phase in BALANSens Platform

Ankle injuries and musculoskeletal disorders often necessitate long-term rehabilitation to restore mobility and balance. The BALANSens robotic platform, designed within the Integrated Balance Rehabilitation (I-BAR) framework, combines ankle, balance, and stepping therapies into a cohesive rehabilitation process. This paper focuses on implementing impedance control on the BALANSens platform, which regulates the dynamic interaction between human limbs and the robotic system, making it suitable for active rehabilitation exercises. Traditional impedance control methods rely on costly six-axis force sensors to measure applied torques. However, this work proposes an affordable alternative using multiple load cells placed under the foot sole. These load cells not only measure ankle joint torques but also capture foot pressure distribution data, a key factor in the later stages of rehabilitation. The paper presents the derivation of joint space impedance control for the platform, with force measurements using load cells, and evaluates the system in a real hardware environment. The results underscore the promise of this approach for active rehabilitation, offering a cost-effective solution that simultaneously enriches the scope of patient assessment data.