In-vitro and in-vivo evaluation of an innovative bio-inspired ankle-foot passive prosthesis

This thesis presents a comprehensive exploration of the development and evaluation of a multi-articular bioinspired powered ankle-foot prosthesis, designed with the distinctive feature of incorporating structures closely mimicked from the human biological counterpart: the B-FootUP. The first model was engineered in 2020 by the PhD P. Mistretta at University of Padova. This early prototype laid the foundation for the subsequent advancements in the prosthetic technology. In 2023, a renewed passive prototype emerged through a collaborative effort with Meccanica Marcato. This partnership led to a refined and enhanced version of the prosthesis: this resulted in a lighter and less obtrusive design, with the overarching objective to diminish the disparity between artificial and biological limbs, and focusing on enhancing mobility and quality of life for individuals with lower limb amputations. Integral to the research is the study and utilization of the sophisticated 'Walking Simulator' testbed, meticulously designed to facilitate in-vitro evaluation of the prosthetic ankle-foot. This unique testing platform replicates the complex biomechanical patterns associated with human walking, allowing for objective, repeatable, and safe assessments. It proved to successfully reproduce gait patterns consistent with those observed in individuals without limb impairments, thus validating its efficacy. The critical phase of this research involves integrating in-vitro simulations with in-vivo testing, providing a holistic understanding of the prosthetic device's performance. Utilizing motion capture technology and force platforms, kinematics and kinetics data are collected. Multiple configurations and elastic actuator stiffness values are examined through various walking and flex trials. The outcomes of these experiments reveal areas for further refinement and optimization of the prosthetic device. While it successfully replicates many aspects of natural limb movement, limitations become evident, particularly in plantarflexion during the propulsive phase due to the absence of active muscle control. Additionally, fine-tuning the spring's stiffness to better replicate the Achilles tendon and adjusting the aponeurosis stiffness are identified as essential avenues for improvement. This thesis represents a significant stride toward achieving this goal, with a commitment to ongoing research and innovation in the field of prosthetic technology.