Conference Paper

Prototype design and realization of an innovative energy efficient transfemoral prosthesis

Fac. of Electr. Eng., Math. & Comput. Sci., Univ. of Twente, Enschede, Netherlands
DOI: 10.1109/BIOROB.2010.5626778 Conference: Biomedical Robotics and Biomechatronics (BioRob), 2010 3rd IEEE RAS and EMBS International Conference on
Source: OAI

ABSTRACT In this paper, we present the prototype realization of the conceptual design of a fully-passive transfemoral prosthesis. The working principle has been inspired by the power flow in human gait so to achieve an energy efficient device. The main goal of this paper is to validate the concept by implementing in a real prototype. The prototype, in scale 1 : 2 with respect to the average dimensions of an adult human, is based on two storage elements, which are responsible for the energetic coupling between the knee and ankle joints during the swing phase and for the energy storage during the stance phase. The design parameters of the prototype are determined according to the human body and the energetic characteristics of the gait. The construction of the prototype is explained in details together with a test setup that has been built to evaluate the prototype.

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    ABSTRACT: In this study, we present the principle design of a fully-passive transfemoral prosthesis for normal walking, inspired by the power flow in human natural gait. The working principle of the mechanism is based on three parts, which are responsible of the energetic coupling between the knee and ankle joints. The design parameters of the prosthesis have been determined according to the energy absorption intervals of the natural human gait. Simulation results show that significant amount of energy can be stored to deliver for ankle push-off generation. The CAD representation of the prototype that is under tests is also presented.
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    ABSTRACT: This paper investigates the feasibility of generating a natural looking walking gait during the swing phase for a transfemoral prosthetic leg. This prosthesis has a powered knee joint and a passive ankle joint, and is designed to be differentially flat. The diffeomorphism between the physical space and the flat output space provides a mathematical framework to solve the challenging trajectory attainment problem. The proposed methodology is demonstrated by both simulation and experiments.
    Robotics and Automation (ICRA), 2013 IEEE International Conference on; 01/2013
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    ABSTRACT: Despite tremendous improvements in recent years, lower-limb prostheses are still inferior to their biological counterparts. Most powered knee joints use impedance control, but it is unknown which impedance profiles are needed to replicate physiological behavior. Recently, we have developed a method to quantify such profiles from conventional gait data. Based on this method, we derive stiffness requirements for knee prostheses, and we propose an actuation concept where physical actuator stiffness changes in function of joint angle. The idea is to express stiffness and moment requirements as functions of angle, and then to combine a Series Elastic Actuator (SEA) with an optimized nonlinear transmission and parallel springs to reproduce the profiles. By considering the angle-dependent stiffness requirement, the upper bound for the impedance in zero-force control could be reduced by a factor of two. We realize this ANGle-dependent ELAstic Actuator (ANGELAA) in a leg, with rubber cords as series elastic elements. Hysteresis in the rubber is accounted for, and knee moment is estimated with a mean error of 0.7 Nm. The nonlinear parallel elasticity creates equilibria near 0deg as well as 90deg knee flexion, frequent postures in daily life. Experimental evaluation in a test setup shows force control bandwidth around 5-9 Hz, and a pilot experiment with an amputee subject shows the feasibility of the approach. While weight and power consumption are not optimized in this prototype, the incorporated mechatronic principles may pave the way for cheaper and lighter actuators in artificial legs and in other applications where stiffness requirements depend on kinematic configuration.
    IEEE/ASME Transactions on Mechatronics 08/2014; · 3.14 Impact Factor

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