Number Synthesis of New Prosthetic Knee Mechanisms Alinne Geronimo (B ) , Rodrigo Luis Pereira Barreto, Elias Ren˜ a Maletz, Vin´ ıcius Noal Artmann, Mˆ onica Raquel Alves, Rodrigo de Souza Vieira, and Daniel Martins Federal University of Santa Catarina, Florian´opolis, Brazil {alinne.geronimo,r.barreto,elias.maletz,vinicius.artmann, monica.alves}@posgrad.ufsc.br, {rodrigo.vieira,daniel.martins}@ufsc.br Abstract. Lower limb prostheses are used to replace amputated limbs promoting gait and controlled movements. Being a complex joint, human knee movements are difficult to reproduce. The majority of knee mech- anisms on the market are designed with four-bar mechanisms and a few still see the knee joint as a single rotation joint. This paper presents the number synthesis of mechanisms capable of reproducing knee move- ments. To do so, new kinematic chains for prosthetic knee mechanisms are explored. The number synthesis results on three loops kinematic chains capable of generating similar movements to human knee, enabling simultaneous rotation and translation movements and keeping only one degree of freedom. Keywords: Mechanisms · Prosthetic · Knee · Number synthesis 1 Introduction The knee joint system is a quite complex joint for the development of prostheses, as these devices must allow controlled movement while walking and unrestricted movements when sitting or bending the knee. Prostheses are artificial devices, such as artificial arms or legs, that are attached to or worn on a body to replace lost limbs [8]. The amputation level defines the selection criteria of prosthesis. For a thigh level amputation, a transfemoral prosthesis is used. Lower limb amputations requires prosthesis that ensures conditions for the user to be able to move safely, exerting efforts compatible with the intensity of gait with minimum discomfort. Robotic prostheses are intelligent devices, with the objective of replacing a body part using external power source or even the amputee’s own propulsion [5]. The main objectives of using a lower limb prosthesis is to promote comfortable, safe and natural walking for the user while performing most varied activities. This paper studies the potential of innovation on new mechanisms capa- ble of reproducing knee movements by analyzing kinematic chains. To do so, c  The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 M. Pucheta et al. (Eds.): MuSMe 2021, MMS 94, pp. 19–26, 2021. https://doi.org/10.1007/978-3-030-60372-4_3