Energy efficient lower limb prostheses

单侧经股截肢者步态比健全步态消耗高达60%的能量。对于更高水平的截肢者，研究表明能源效率下降了80%以上。最近的研究表明，高水平截肢者在斜坡上行走时的能量消耗显着增加，这表明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的步行速度通常降低40%而加剧，这些截肢者具有相关的低活动水平，特别是在老年截肢者中。这些缺陷在双侧截肢者中甚至更大。这对截肢者的成就和生活质量产生了巨大的影响。假肢的能量储存和返回能力对于改善这种情况至关重要，但现代假肢仅在膝盖以下储存和返回大量能量，并且能量不能以受控的方式返回。例如，在站立结束时，储存的能量不可用于跖屈（蹬离）。此外，现代假肢系统不会在关节之间传递能量，这是一个失去的机会，因为例如，膝盖处的过量偏心功可以在其他关节处以受控的方式存储和使用。基于这些原因，我们相信有机会进行真正的变革性研究，从而使下肢假肢的性能发生重大变化。我们一直在进行模拟研究，以确定液压技术在下肢假肢中实现受控存储、关节间传输和能量返回的潜力。这项工作显示出很大的希望，我们已经从出版我们的结果，因为保护知识产权的可能性。尽管迄今为止的工作主要集中在经胫骨截肢者的假肢上，但这种方法在提高经股骨截肢者步态的能量效率方面具有更大的潜力。因此，在本项目中，我们将探索踝关节、膝关节和髋关节的能量储存、传递和返回;后者是为了评估截肢者通过髋关节矫形器从额外的能量储存和返回中受益的潜力。我们专注于液压设计，因为它们在假肢应用中具有独特的优势。由于液压系统通常在200至400 bar的压力下工作，因此具有非常高的功率密度，因此非常适合假肢的重要要求--整形。短期能量存储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，因为传递机制只涉及管道和流体，而不是齿轮和连杆。这对于高位截肢者来说尤其重要，如果膝关节处的过度离心功能够以受控的方式存储并用于其他关节，则他们可以受益。为了实现我们的目标，我们将建立在我们的研究在三个领域，这对应于三个主要的工作包（WP）。WP 1将开发和模拟替代概念设计。WP 2将建立一种方法来预测截肢者可能会以何种方式使他们的步态适应替代假肢。WP 3将提供步态实验室数据：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.