A Biomimetic, Self Tuning, Fully Adaptable Smart Lower Limb Prosthetics with Energy Recovery

Every year, thousands of people lose a lower limb as a result of a range of factors such as circulatory problems, complications of diabetes or trauma.
Current lower limb prostheses can be divided into three groups: i) Purely passive mechanical and requiring a significant voluntary control effort; ii) Actively controlled in which the limb performance is measured and parameters altered to improve performance; iii) Actively driven, or powered prostheses using actuators to directly input mechanical work into the limb. The latter devices do not take into consideration the dynamic interaction between the body elements and prostheses. As a result, they require large amounts of energy and have low efficiency. Therefore they are not in harmony and synergy with the human body. Hence, there is a need for a new generation of lower limb prostheses which can mimic the human muscle by combining active and passive modes.
The new generation of prostheses should have a plug and play characteristic and the limb would self tune to the current walking situation (level, slopes and stairs) to optimise the system performance to the user. During the walking cycle, the artificial limb will switch between delivering energy to the walking motion to harvesting energy during the swing phase; prolonging battery power and reducing the burden on the batteries.
The aim of this project is to design and develop a new smart lower limb prosthesis through a research programme structured around the following activities.
1) Use of body hub sensors to measure gait dynamics in real time;
2) Use of prosthesis integrated sensors interfaced with the human limb to measure reaction loads during prosthesis use;
3) Estimation of user intent and evaluation of the potential for haptic or other forms of feedback from the prosthesis to enhance its usability;
4) Optimisation of energy use through dynamic coupling and energy generation; and
5) Improvements in limb comfort associated with extended periods of wear.
The outcome of the research will be a step change towards the use of technology in relation to the human body and mobility considering human-machine dynamic interaction. The research outcomes will address a number of healthcare challenges associated with the restoration of mobility in amputees, and paves the way for a new direction in the design and development of devices to support mobility in an aging population and applications such as the rehabilitation of stroke patients. The world's third largest manufacture of prosthetics is in the UK and this research will boost the advancement of the UK position worldwide by providing enhanced opportunities for commercialisation.

This research will have a significant academic impact. New and innovative approaches to the design and control of lower limb prosthetics will enable other researchers to develop variants of the technology applicable to sectors such as upper limb prosthetics, rehabilitation and walking robots.
Maximising the impact of the research is central to the research strategy. During the project, our user group consisting of amputees, their families and care professionals will participate to ensure the quality and relevance of this work.
Academic dissemination will be achieved through publications and conferences such as ICORR and CLAWAR and presentations at annual prosthetic events.
The outcome of this work will be a fully designed and validated system ready for testing on human subjects. An evaluation of transferring the research results into other domains will be done.
However, it is recognised that the full impact will not be achieved until the system has gone through a process of clinical testing and evaluation. For this reason, by the end of year two, an application for further funding will be made for the testing and evaluation stages and to produce the device. The device will need to gain MHRA approval for a class 2 device (active device). The team has experience with this procedure through the iPAM rehabilitation robot and are aware of the timescales and lengthy documentation. Possible funding routes include:
1) A Knowledge Transfer Partnership grant (KTP) with Blatchfords;
2) NHS i4i funding - Members of the team have previously been involved in such a proposal. This second stage funding will prove the technology for use on human subjects and provide indications of the expected clinical performance. Following on from this stage either:
(i) Commercialisation of the technology would be undertaken through Blatchfords, or
(ii) Further funding would be sought for a full clinical trial.
The decision on which route to take, will be made during the second stage of the research programme, and if appropriate, applications made to ensure there are no funding gaps. The device would then be commercially released.
The potential impact of this proposal goes well beyond a single successful product. The prospective advances in predicting user intent are a radical forward step with the potential to become standard on all prosthetics, and the team will follow up advances with further technical applications to funding bodies such as EPSRC. The sensor systems used to measure body motions can be applied in other areas such as detecting differences in gait in people with, for example Alzheimer's prior to a wandering episode. Actuation systems developed in this work could be altered for use in prosthetic upper arms (we have close links with RSL steeper, a world class upper limb prosthetic company) or in ankle joints.