The EU FET Symbitron project gathered researchers from 5 European countries to build wearable exoskeletons to help people who have suffered a spinal cord injury to walk again. The next step is to prepare the robot to compete at the Cybathlon games in 2020 in Zurich.
One of human beings’ most interesting features is the interaction between the mind and the body, and hence the control that the brain exerts on the body and the continuous feedback received from it. Spinal cord injuries (SCI) interrupt the crucial bi-directional communication pathway between the brain and the rest of the body, and make it difficult or impossible for patients to walk.
At the moment, although scientific advances are being made, there is no way of regenerating and totally restoring a damaged spinal cord and the nerve pathways connected to it. Nonetheless, researchers in the field of assistive robotics are currently working to develop wearable devices that can compensate for lost motor functions. Over the past four years, scientists in the Symbitron project, supported by the EU FET programme, developed lower limb exoskeletons that people with SCI can use to walk again. The multidisciplinary team included mechanical, electronic and biomedical engineers, neurologists, psychologists and physical therapists.
Project researchers from 5 European countries (the Netherlands (University of Twente and Delft University of Technology), Italy (Fondazione Santa Lucia IRCCS), UK (Imperial College), Switzerland (EPFL) and Iceland (Össur), developed a versatile wearable robot adaptable for use by SCI patients with very different impairments. Their great ambition was to let patients walk autonomously, regain their mobility and independence, and overcome the psychological barriers created by their disability.
One of the main challenges to be faced was to overcome the traditional engineering design approach, which often focuses almost exclusively on technological issues and only partially takes into account the perspective and clinical needs of users. The Symbitron project put the patients at the center of the exoskeleton design paradigm, trying to tailor the technology around their body, their mind and the residual communication between them that is still possible. From the very beginning of the project, 13 patients with SCI, each one with unique clinical features related to specific spinal cord damage, were involved as part of the experimental team and considered as “test pilots” of the machine to be developed. Their precious feedback on performance and their experience of using the technology was successfully embedded in a user-centred optimisation loop, in which great attention was given to robotic adaptation and customization aspects, as these are key to ensuring that the human-machine interaction works as well as possible.
Form the hardware point of view, the exoskeletons were designed in an innovative modular format, making different robotic configurations possible: for example, to support the ankle or knee joints of patients who still have some ability to walk independently, or the entire legs of those with more severe SCI who cannot walk unaided. The control software was designed to be flexible to match. A biologically inspired control algorithm was developed to mirror muscular and reflex-like movements in the legs of the exoskeletons and to let the users control the machine and walk in a smooth, intuitive and natural way. Not only engineers and clinical experimenters, but also the “test pilot” patients, were actively involved in honing the software’s functions and its use to control the machines: their feedback was crucial.
The test pilots were involved throughout the project in several experiments to obtain neurophysiological information useful for the mechatronic design process, personal experiences needed to customize the behavior of the exoskeletons, and biomechanical data on human-robot performance to improve the hardware and software. A major project milestone was a “measurements marathon” organized at the University of Twente. Nine test pilots moved from the Italian clinical partner, Fondazione Santa Lucia IRCCS, to the Netherlands to take part to 5 full days of testing, including 11 different experiments (around 120 different tests), which involved 14 Symbitron researchers and 3 experimental setups.
The Symbitron project was successfully concluded in Rome with clinical approval of the modular exoskeleton it developed, demonstrating the possibility of improving the walking performance of the test pilots after a period of training performed in a clinical setting. The tests were proof of the feasibility of Symbitron’s unique approach. Moreover, a multi-factor psychological assessment showed that the users were not only highly motivated through the training but also very satisfied about the capacity of the exoskeleton to adapt to their personal walking and balance strategies. The Symbitron exoskeleton will be further developed in the years to come in order to compete in the Cybathlon games in 2020 in Zurich.