Energy efficient lower limb prostheses

单侧经股截肢者的步态比健全的步态多消耗60%的能量。研究表明，对于截肢率较高的截肢者，能效会下降80%以上。最近有研究表明，高位截肢者在斜坡上行走时的能量消耗显著增加，这表明对水平行走的研究可能低估了问题的严重程度。高能量消耗的负面影响因经股截肢者步行速度降低通常40%而相关的低活动水平而加剧，特别是在老年截肢者。这些赤字在双侧截肢者中甚至更大。这对截肢者的能力和他们的生活质量产生了巨大的影响。假体的能量存储和返回能力对于改善这种情况至关重要，然而现代假体只存储和返回膝盖以下的大量能量，并且能量不是以受控的方式返回的。例如，在站立结束时，储存的能量不适用于足底屈曲(推离)。此外，现代假肢系统不会在关节之间传递能量，这是一个错失的机会，因为例如，膝盖上多余的偏心功可以被储存起来，并以受控的方式在其他关节使用。出于这些原因，我们相信有机会进行真正的变革性研究，从而导致假肢性能的逐步变化。我们一直在进行模拟研究，以建立液压技术的潜力，以实现双腿假肢的受控储存、关节之间的转移和能量的返回。这项工作显示出巨大的前景，我们没有公布我们的结果，因为有可能保护知识产权。虽然到目前为止，这项工作主要集中在胫骨截肢者的假体上，但这种方法在提高股骨截肢者步态的能量效率方面具有更大的潜力。因此，在这个项目中，我们将探索踝关节、膝关节和髋关节之间能量的储存、传递和返回；后者是为了评估截肢者从一些额外的能量存储中受益并通过髋关节矫形器返回的潜力。我们专注于水力设计，因为它们在假体应用中具有独特的优势。由于它们通常在200到400巴的压力下工作，液压系统具有非常高的功率密度，因此非常适合微型化，这是假肢的重要要求。短期储能是液压蓄能器非常适合的另一个重要要求。最后，液压驱动非常适合在关节之间传递能量，因为传递机构只涉及管道和流体，而不涉及齿轮和连杆。这对更高水平的截肢者尤其重要，如果膝盖上多余的偏心功能够被储存起来，并以受控的方式在其他关节使用，他们可能会受益。为了实现我们的目标，我们将在三个领域进行研究，这三个领域与三个主要工作包(WPS)相对应。WP1将开发和模拟替代概念设计。WP2将建立一种预测截肢者可能调整步态以适应替代假体的方法。WP3将提供步态实验室数据，用于：验证步态预测方法；并为概念设计提供信息。

Unilateral trans-femoral amputee gait consumes up to 60% more energy than able-bodied gait. For higher level amputees, research suggests that energy efficiency drops by well over 80%. Recently it has been shown that energy consumption in high level amputees increases significantly when walking on slopes, suggesting studies in level walking may underestimate the extent of the problem. The negative effects of high energy consumption are compounded by reductions in walking speed of typically 40% for trans-femoral amputees with associated low activity levels, particularly in elderly amputees. These deficits are even greater in bilateral amputees. This has a tremendous impact on what amputees can achieve and the consequences for their quality of life.The energy storage and return capabilities of prostheses are crucial to improving the situation and yet modern prostheses only store and return significant energy below the knee, and energy is not returned in a controlled manner. For example, stored energy is not available for plantar-flexion (push-off) at the end of stance. Furthermore, modern prosthetic systems don't transfer energy between joints, which is a lost opportunity as, for example, the excess of eccentric work at the knee could be stored and used in a controlled manner at other joints. For these reasons, we believe there is an opportunity for truly transformative research leading to a step change in the performance of lower limb prostheses.We have been undertaking simulation studies to establish the potential for hydraulic technology to enable controlled storage, transfer between joints, and return of energy in lower limb prostheses. This work is showing great promise and we have held back from publishing our results because of the possibility of protecting the intellectual property rights. Although the work to date has focussed on prostheses for trans-tibial amputees, this approach has even greater potential for improving the energy efficiency of trans-femoral amputee gait. Therefore, in this project, we will explore storage, transfer between joints, and return of energy involving ankle, knee and hip; the latter being to evaluate the potential for amputees to benefit from some additional energy storage and return via a hip orthosis.We are focussing on hydraulic designs because of their unique advantages for the prosthetics application. Because they typically operate at pressures of 200 to 400 bar, hydraulic systems have very high power densities and are therefore well suited to miniaturisation, an important requirement in prosthetics. Short term energy storage is another important requirement for which hydraulic accumulators are well suited. Finally, hydraulic actuation is ideally suited for transferring energy between joints because the transfer mechanism involves only pipes and fluid, rather than gears and linkages. This is of particular importance for higher level amputees who could benefit if the excess of eccentric work at the knee could be stored and used in a controlled manner at other joints. To achieve our objectives we will build on our research in three areas, which correspond to the three main work packages (WPs). WP1 will develop and simulate alternative concept designs. WP2 will establish a methodology for predicting the ways in which amputees might adapt their gait to alternative prosthesis. WP3 will provide gait laboratory data for: validating the gait prediction methodology; and informing the concept designs.