The objective of this research activity is to analyze and model the behavior of ReWalk™ exoskeletons during SCI patients training.
Powered exoskeletons can be used by persons with complete spinal cord injury (SCI) to achieve bipedal locomotion. The training required before being able to efficiently operate these orthotics, however, is currently based on subjective assessments of the patient performance by his therapist, without any quantitative information about internal loads or assistance level.
To solve this issue, a sensor system was developed, combining traditional gait analysis systems such as ground reaction force (GRF) platforms and motion capture systems, with instrumented Lofstrand crutches, created by our team.
To each crutch three strain-gauge bridges were applied, to measure both axial and shear forces, as well as conditioning circuits with transmission modules, a tri-axial accelerometer, and a power management circuit with two batteries. Data are transmitted wirelessly via Bluetooth to a personal computer, and every care was taken to avoid interfering with the user’s gait.
An inverse dynamics analysis, on a simplified biomechanical model of the subject wearing the exoskeleton, is then used to assess both the internal forces acting on shoulders, elbows and neck of the subject, as well as the loads acting on joints. The same analysis was also used to quantify the assistance provided to the user during walking, in terms of vertical forces applied by the therapist to the exoskeleton.
These information could be used to teach orthopedic patients to correctly use these supports and minimize problems connected to their usage, making easier for SCI patients to adopt these devices, and increasing their quality of life, while reducing the costs sustained by the community.
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