Toward the design of a new ankle prosthesis
Geometry and mechanics of the human ankle complex and ankle prosthesis design
Design and Evaluation of a Passive Ankle Prosthesis …
Series elastic actuators are very popular in rehabilitation robotics. Among other advantages, elastic elements between the actuator and the load permit to store and release energy during the task completion, such that the energy balance is improved and the motor power peak is decreased. In rhythmic tasks like walking, this reduces to design the spring stiffness such that it works at resonance.
For this aim, we propose a geometric model of a conceptual prosthesis in the sagittal plane. This model was directly inspired by the series of the SPARKy devices developed by Sugar et al.  The active movement is transmitted to the ankle via a ball screw through one spring. The constitutive geometric parameters (i.e. R1, R2, etc...), such as the springs stiffness were optimized to reduce the motor power peak with an objective function which is the maximum power peak supply by the motor.
During the early stance phase, the motor loads the spring, which is further loaded during the load acceptance phase. During the late stance phase, the spring releases its energy (giving rise to a power peak close to the one of the healthy ankle), while power provided by the motor is very small. Without the spring, the motor would have to reproduce the power profile of a healthy ankle (peak of 170W). With the spring, the peak power is only of about 60W. In sum, the maximum power peak in the motor is decreased by a factor 3 .
Starting from these previous works, we want to design an ankle controller able to adapt the prosthesis behavior to changing walking speed. Adaptive Oscillators (AOs)  are a set of differential equations able to learn any cyclic signal and to extract its caracteristic phase, frequency, amplitude and offset. Using this mathematical tool to extract the walking pace allows to fine tune sensory-motor reflexes of the neuromuscular model. Furthermore, AOs can be used as a feedforward motor command to muscle stimulation, or to anticipate swing/stance transition.
Orthotic & Prosthetic Design
 Bellman et al., Sparky3: design of an active robotic ankle prosthesis with two actuated degrees of freedom using regenerative kinetics, Biomedical Robotics and biomechatronics, pp.511-516, 2008
Transtibial amputation can alter considerably the quality of life. Passive prosthesis (without energy supply) can restore basic locomotion but lacks the ability to produce healthy-like gait support. Indeed, the ankle joint needs high power peaks to propel the whole body forward during ankle pushoff. Without this power, an increase in metabolic energy consumption might appears due to muscles and joints fatigue. A motorised ankle prosthesis is therefore necessary to restore natural gait. This project aims at designing an active artificial ankle which mimick biological functions. Its mechanical conception targets a minimization of electrical energy consumption with the use of a serie elastic actuator. Both simulations and real tests are under development to setup bio-inspired reflexes able to adapt changing walking speed.
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The Rio Tinto Sports Innovation Challenge aims to promote the development of innovative sporting equipment for people with disabilities. Focusing on the Sochi 2014 Paralympic Winter Games, an opportunity was recognised in the limited equipment available for cross-country skiing and biathlon. The project focused on designing, manufacturing and testing a prosthetic ankle joint and foot for above and below knee amputees.
The detailed kinematics were identified based on literature and video footage analysis. Various models were created to understand the different ranges of motion observed in the knee and ankle in the different skiing modes. Athlete and bilateral leg amputee David Henson, as well as former Olympic biathlete Mike Dixon were consulted to refine the specifications of the prosthesis. With the help of experts at the London Prosthetic Centre, a suitable off-the-shelf knee joint was identified.
Geometry and mechanics of the human ankle complex …
Author links open overlay panel Alberto ..
Prosthetics are commonly called artificial limbs and are used to replace ..
INBONE™ Total Ankle System - Total Ankle Institute
21/01/2017 · Ankle-Knee prosthesis with powered ankle and energy ..
By offering the first total ankle system that provides ..
The INBONE ™ Total Ankle System is a modular prosthesis ..
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