Control of Prosthetic Hands: Challenges and emerging avenues
This edited book brings together research from laboratories across the world, in order to offer a global perspective on advances in prosthetic hand control. State-of-the-art control of prosthetics in the laboratory and clinical spaces are presented and the challenges discussed, and the effect of user training on control of prosthetics to evaluate the translational efficacy and value for the end-user is highlighted. The book begins with a chapter introducing the fundamental principles, engineering challenges and control solutions for prosthetic hands. Further chapters address methods to design bespoke sockets, magnetomyography, implantable technologies for closed-loop control of prostheses, direct neural control of prostheses via nerve implants as well as user-prosthesis co-adaptation, and two chapters on prosthetics for children. The book concludes with a chapter by Dr Nazarpour on the future of myoelectric prosthetics control, with particular focus on the successful translation of research advances into real clinical gains. The book is essential reading for anyone involved in research or undertaking advanced courses in prosthetic design and control. It provides an in-depth exploration of this rewarding topic, by exploring technologies with the potential to improve the quality of life of upper-limb prosthetic users.
Inspec keywords: dexterous manipulators; biomagnetism; surgery; closed loop systems; paediatrics; grippers; prosthetics; electromyography
Other keywords: nerve implants; direct neural control; surgery; child prosthetics; user-prosthesis coadaptation; clinical evaluation methods; amputee residual limb pain management; soft grippers; bespoke socket design; prosthetic hand control; implantable technologies; magnetomyography; myoelectric prosthetics control; closed-loop control; transradial upper limb prosthesis
Subjects: Monographs, and collections; Biomagnetism; General electrical engineering topics; Biomagnetic signals; Bioelectric signals; Prosthetics and other practical applications; General and management topics; Manipulators; Patient care and treatment; Prosthetic and orthotic control systems; Prosthetics and orthotics; Electrodiagnostics and other electrical measurement techniques
- Book DOI: 10.1049/PBHE022E
- Chapter DOI: 10.1049/PBHE022E
- ISBN: 9781785619847
- e-ISBN: 9781785619854
- Page count: 233
- Format: PDF
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Front Matter
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1 Control of prosthetic hands
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We provide a review of the various methods for the control of active prosthetic hands. We introduce various conventional and contemporary approaches and lay the foundation of more advanced techniques that could achieve the holy grail of prosthesis control, that is, the continuous control of individual digits and wrist joints. Topics discussed include clinical aspects; bespoke sockets and clinical outcome measures; methods that enable interfacing directly with the nerves and muscles; surgical techniques; artificial intelligence and machine learning; user-prosthesis co-adaptation; children prosthetics; and 3D-printed prosthesis.
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2 Methods to design bespoke sockets
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The socket is an integral and important part of the prosthetic limb, providing link between body and technology. The quality of this connection must be considered as we strive towards embodiment of the prosthetic limb. The purpose of the socket is not just to provide a container for the residual limb but to provide a vessel where biomechanical forces can be transmitted from the body to the prosthetic componentry in the most energy -efficient manner while protecting the underlying tissues. The residual limb consists of bone surrounded by an envelope of soft tissues, including muscles which may no longer have insertion points. As the bone is able to move within the envelope of soft tissues, poor transmission of force and discomfort within the prosthesis can occur. Stabilising tissues to minimise bone movement within the socket is considered one of the primary goals in designing and constructing a well-fitting socket
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3 Methods for clinical evaluation
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This chapter begins with an introduction to the challenges of measurement in upper limb prosthetics. This is followed by an overview of the traditional approaches to evaluation and their strengths and weaknesses. By traditional approaches, we mean tests involving observation of a participant performing a structured activity or reporting on their everyday experiences and behaviours through questionnaires. These approaches generally involve little, if any, instrumentation and are still widely used. In the next section, we report on the evaluation tools which have emerged from studies of human motor control; these include observation of the kinematics during the performance of tasks and measures which may reflect attentional demands, such as gaze behaviours and brain activity. As the so-called conventional methods and the human-motor-control-based methods either observe behaviours over a short period of time or ask people to accurately recall and report on their behaviours, both have inherent limitations. Finally, we report on methods which can be used to capture, in detail, the everyday upper limb behaviours of people in the real world and discuss the opportunities such real-world approaches open up around data analysis at scale.
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4 Magnetomyography
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Signals produced by skeletal muscle can be utilised for monitoring and treatment of different movement and neurological disorders. The study of muscle function through measurement of biomagnetic signals is called magnetomyography (MMG). However, the level of biomagnetic signals is extremely small and developing highly sensitive sensors to detect them is outstandingly challenging. Current technologies for detection of such weak biomagnetic signals are bulky, costly and hospital-based. The research findings are yet to develop miniaturised, sensitive and low-cost MMG sensors. This chapter describes the state-of-the-art magnetic sensing technologies that have the potential to realise a low profile and possibly implantable MMG sensor.
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5 Implantable technologies for closed-loop control of prosthesis
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In this chapter, we will give an overview of the human nervous system, state-of-the-art neural interfaces and their application in upper limb amputees and paralyzed patients and how they can improve the quality of life.
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6 Direct neural control of prostheses via nerve implants
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The primary goal of direct neural control is to provide a seamless interface to the body's own control and feedback systems. In the case of an upper limb amputation, such an interface would ideally enable a direct mapping of motor commands and sensory feedback to and from a prosthesis and the undamaged portion of the nervous system. In theory, this interface could be constructed in such a way that control of the prosthesis was transparent to the user, feeling as close as possible to the original limb. This idealised paradigm would require no training or learning on the part of the user or the prosthesis. To provide this level of natural control, an interface is required between the peripheral nervous system (PNS) and the prosthesis. In practice, of course, no such ideal interface exists. However, recent developments in electrode design, biocompatible materials and signal processing are paving the way for the emergence of superior interfaces in the future.
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7 Surgical considerations for advanced prosthetic control and residual limb pain management in amputees
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Amputations are typically more common in the lower limb due to diabetes and vascular disease than the upper limb, where the leading aetiology is trauma, although this does vary between developed and developing countries [1,2]. In both situations, traditional surgical teaching has focused on leaving enough soft tissue to cover the residual bone for comfortable prosthetic fitting [3]. Involved nerves are usually cut under tension, so that the nerve stump becomes buried under muscular soft tissue to prevent painful neuromas at the amputation site itself, which will prevent comfortable socket fitting. However, with advances in secondary surgical procedures following amputation, new evidence is suggesting that nerve transfers may prevent resulting pain symptoms.
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8 User-prosthesis coadaptation
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The system has to have a robust behavior against the different disturbances the user will face during the time they are using the prosthesis. The electrodes will not be always placed in the same location, the EMG patterns will change for the same movement depending on the arm position, fatigue or other external conditions will affect the system. The prosthesis cannot have an erratic behavior depending on external states unavoidable for the user. Thus, an optimal system should be usable in almost all common conditions with a high performance and not only in controlled environments. At the same time, the easy use of the prosthesis is also important. Tedious training protocols and complicated control structures, in order to achieve a robust performance, are not a solution and will lead to rejection. The use of a prosthesis has to be intuitive and natural, and for this a clear communication between the two agents is essential. Here the training paradigms play a key role and researchers will have to give them the attention proportional to their high relevance in the final outcome. For this, it is essential that the training procedures are clear for the user so the learned model is consistent. Coadaptive models are potential candidates to achieve these requisites. So the model is shaped by the user's learning and therefore by their comprehension of the system. These models will be then more logical for the own user and adapted to their way of understanding the control, increasing the final usability.
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9 Child prosthetics – a perspective
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This chapter summarises conversations between researchers working in healthcare and academia linked through membership of the Starworks Network, a UK National Institute for Health Research initiative to accelerate the translation of child prosthetics research into daily use. Specifically, it aims to unpack challenges identified by the network and critically analyse the current 'state of the art' in relevant upper limb myoelectric prostheses areas, informed by multiple perspectives. Each section outlines an area of emerging influence over the past decade which is likely to remain influential over the next. It begins with a brief introduction to the Starworks Network and concludes with recommendations from the authors
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10 Design and development of transradial upper limb prosthesis for children with soft-grippers
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This work presents a myoelectric device for toddlers that can be produced at a low cost while maintaining high grasp performance levels. To achieve this, cable-driven soft-grippers have been integrated into the design, with the intention of improving the grasp contact surface. The soft-grippers also aim to provide a more even distribution of the grasp force, mimicking the grip force distribution of a human hand. The device has been named SIMPA : Soft-grasp Infant Myoelectric Prosthetic Arm.
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11 The future of myoelectric prosthetics control
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In this chapter, I will review these three factors. However, one must acknowledge that there are many other factors that fall outside the remit of this book. For example, the overall cost of the device, including the industrial research and development, manufacturing and testing, standardisation, marketing and commercial costs is one such factor. Together, these factors increase the ultimate price. Different local -level or national -level governmental policies and those by the insurance companies can also affect the affordability of the device.
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Back Matter
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