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Prototype of robotic ankle-foot prosthesis with active damping using magnetorheological fluids

Abstract:

When an amputee walks around wearing a transtibial prosthesis that does not have adequate range of motion and cushioning, the person will have a very irregular gait. For this reason, this project is aimed at the design and implementation of an ankle and foot prosthesis, which takes advantage of technological advances, uses intelligent materials such as magnetorheological fluids (MRF) and applies computer processes to develop a prototype that guarantees a harmonious and functional gait without neglecting the aesthetic aspect; based on the study of the anatomy, biomechanics and locomotion of the lower limb, in order to provide a natural movement. A hybrid magnetorheological system was designed, equipped with a torsion limiting mechanism that emulates the movement of the ankle and foot that occurs in the sagittal plane, controlling the damping, rotation and stability, through a system that generates and controls the magnetic field that is applied to the MRF, providing greater adaptability to the patient. Tests have shown that the prosthesis meets the design requirements, as the electric actuator is positioned in such a way that the first contact with the floor is made only with the heel of the prosthesis, then the MR fluid damper absorbs the impact and finally the electric actuator gives the necessary impulse to complete the next step. The prototype is capable of replicating the angle and torsion patterns of the human ankle, for a stride speed of up to 2.8 m/s.