The XoSoft project has developed a novel type of soft lower limb exoskeleton to assist people with mobility problems like muscle weakness, loss of sensory functions and spinal cord injury (SCI). “We developed a modular biomimetic exoskeleton that followed a user-centred design approach, including step-by-step production of four different prototypes,” outlines Dr Jesús Ortiz, project coordinator. Stepwise progress for Alpha, Beta 1, Beta 2 and Gamma prototypes Beta 1 was the first to use soft technologies to integrate sensing and actuation with the garment and Beta 2 represents a big step towards a complete soft system. Gamma is the crème de la crème version. This is a totally soft system comprising innovative technologies from different partners who worked together during all the phases of the project – from identification of the clinical needs to the final integration and validation of the prototype. While the soft material nature of the system has great potential in terms of gaining user acceptance, a number of technical challenges had to be overcome. “Consequently, we targeted different technical areas such as soft actuation, soft sensing and biomimetic control,” emphasises Dr Ortiz. Soft versus hard systems Different soft smart materials developed by the team permit sensing capabilities integrated directly into textiles/clothes, not possible with classical rigid systems. The use of new soft materials enables lower weight, compactness and increased comfort. Accurate monitoring of 3D absolute posture and movement in the subject is important for maintaining balance in XoSoft. “The production of a soft actuation system suitable for the XoSoft concept was a challenge from the beginning of the project,” Dr Ortiz reflects. In contrast to rigid exoskeletons, soft exoskeletons have similar degrees of freedom to a human not wearing an XoSoft exoskeleton. Different technological solutions were evaluated, and some of them did not comply with the requirements. “However, with a smart combination of technologies and actuation principles, we successfully developed an actuation system that allowed the realisation of XoSoft in a modular and scalable way.” Each prototype was tested in a laboratory setup with a detailed analysis of the potential benefits. In this setup, the Beta 1 prototype was tested with a post-stroke patient, while the Beta 2 and Gamma prototypes were tested with five subjects. In a second phase, the Beta 2 and Gamma prototypes were tested in a clinical setup with five to seven subjects. Finally, the Gamma prototype was validated in a home-simulated environment with four subjects. The variety of scenarios and patients provided invaluable feedback on the potential benefits of XoSoft. Confident steps on the way to real applications in real scenarios Availability of the three fully working prototypes (one Beta 2 prototype and two Gamma prototypes, classified as medical devices class I) will permit continuation of the testing and the collaboration between partners beyond the project. Furthermore, all the partners are willing to work together in future projects and there are plans to submit a project proposal for future EU funding and development. “This will not only improve the technical capabilities, but also focus the development towards some more realistic application in real scenarios,” sums up Dr Ortiz. Increased system sophistication will identify user motion and intention to provide the required level of assistance.
XoSoft, prototype, soft, beta, gamma, exoskeleton, modular, mobility