Simultaneous Control of Multiple Degrees of Freedom in Myoelectric Hand Prostheses (SimCon)

The aim of this project is to develop a radically novel and biologically-informed control approach that enables simultaneous control of multiple joints in an upper-limb prosthesis.

The loss of any limb, particularly the hand, affects an individual's quality of life profoundly. Advanced prosthetic hands can provide a route to functional rehabilitation by allowing the amputees to undertake their daily activities and improve their chances of returning to their careers and earning their regular livelihood. Surveys on the use of artificial hands reveal that 20% of the amputees abandon their prosthesis with a key reason being that it does not provide enough function. Therefore, performance enhancement of upper-limb prostheses is a pressing need.

The on-off 1-degree of freedom control paradigm that Reinhold Reiter disclosed in a patent application in 1945 is still used widely for prosthesis control. As early as 1967, Finley showed that the on-off control does not offer enough flexibility to the user and proposed the use of pattern recognition to estimate prosthesis user's movement intention by processing electrical activity of muscles, known as the electromyogram or myoelectric signals. Today, 50 years after Finley's proposal and despite remarkable laboratory demonstrations, it has not been feasible to commercialise pattern recognition in a myoelectric prosthesis hand because 1) it is very difficult for the amputees to generate distinct activity patterns for different movement classes and 2) pattern recognition performance often deteriorates due to electrode displacement and movement of the residual limb.

In this project, we will firstly explore the extent to which muscles in the hand and forearm can learn to generate novel co-contraction patterns (aka muscle synergies) because natural synergies may be disrupted by amputation. The insight gained from this experimental work will inform design of novel algorithms to enable simultaneous control of multiple joints (degrees of freedom) movements. These algorithms can self-tune, to improve performance, as the user interacts with the prosthesis. The project will culminate in a pre-clinical trial in which four amputee subjects test the prototyped control algorithm with a prosthesis. The performance of the proposed paradigm will be compared to that of the conventional prosthesis on-off control method.

The proposed research project will produce an efficient approach for simultaneous control of multiple degrees of freedom. This offers the user much greater flexibility than current on-off or pattern recognition-based control approaches. Pilot results show that with this approach the prosthesis can respond to user's motion intention in only 100ms, which is at least three times faster than the state-of-the-art in upper-limb prostheses control. Results of this research will pave the way for future generations of "plug and play" prostheses with "ready-to-go" and "wearer-independent" features.

This project paves the way for the development of novel techniques and procedures to realise the first generation of the upper-limb hand prosthesis that offer the possibility of simultaneous control of multiple-degree of freedom. This project will have a huge impact on upper-limb prosthesis users and the society, the economy, knowledge and finally people involved in this project.

Society: Loss of the hand, and the complexities it entails, is one of the most feared conditions having a huge impact upon individuals, their families and society at large. Use of prostheses can improve the quality of life of amputees dramatically and contribute to their personal dignity, independence and more effective inclusion in the society. Advanced prostheses, for instance, those that offer simultaneous multi-joint control, are thus essential to minimise the effect of this devastating condition. In addition to the loss of function that losing a limb causes, phantom pain and psychological distress can be severe. Life-time care can be remarkably expensive. The challenge to provide effective prostheses is a recurrent feature of comments from users. It has been a key theme in national reports on prosthetic services in the UK [Chavasse report, 2014] particularly in relation to injured service personnel and survivors of major trauma. These issues are discussed regularly during meetings of the All-Party Parliamentary Limb Loss Group. Development of efficient and cost-effective upper-limb prosthetic can improve the quality of life of prosthesis users greatly and enable them to return to work.

Economy: The results of this project will cement the UK's reputation as the leading country for prosthetic design and manufacture: 3 of the 4 major manufacturers of upper- and lower-limb prosthetic limbs are UK-based. The market for advanced prostheses and bionics is growing rapidly. For example, Touch Bionics (UK) had a 23% increase in revenue in 2013. In October 2014, it was announced that Touch Bionics will enter the stock market for an estimated value of £50m. This project will provide significant know-how and novel technologies to help the UK's prosthetics industry remain competitive in a global market. Financial security of the British upper-limb prosthetics industry will help to reduce the production and R&D cost allowing the NHS to cover the cost for a larger number of amputees.

Moreover, able-bodied individuals who want advanced interfaces to better operate or interact with robots or games can also benefit from the results of this work. For instance after the release of GetMyo (Thalmic Labs), the use of muscle signals to interact with gadget has become possible for freelance programmers and application developers.

Knowledge: Understanding the flexibility and limits of the motor systems in learning new skills and their application in prosthesis control are very exciting and timely, as evident by the number recent publications in Nature on these topics. As such, the results of this project can lead to a platform to develop the next generation of truly plug and play prosthetic systems.

People: The research will provide high-quality training in the general areas of signal analysis, stochastic learning and sensorimotor control for the research associate (RA1) in this project. RA1 will gain knowledge and expertise through the process of solving challenging problems and presenting his/her work. RA1 will spend time at both Newcastle University's School of Electrical and Electronic Engineering and Institute of Neuroscience and benefit from a truly multi-disciplinary research environment. The Staff Development Unit at Newcastle University offers many training workshops, e.g. on maximising and measuring research impact. RA1 will be advised to attend all relevant workshops. At the end of the project and with such a skills the RA1 will be fully prepared to go to industry or to stay in academia to pursue an academic career.