Adaptive Control System for Ankle Orthosis T-Flex

Cerebrovascular disease (stroke) is the third cause of mortality in Colombia, and this index has been rising in last years. Stroke can result, as one of its events, in a total or partial loss of gait and, in several cases, this type of consequence is susceptible to rehabilitation. T-Flex is an ankle orthosis based on bioinspired tendons of variable stiffness, which is used to help and rehabilitate patients with gait disturbances. Its function is to provide specialized assistance during the different phases of the walk. Systems such as T-Flex require a control mechanism that allows to adjust the type and level of assistance according to the performance of the movement in each of these phases. In this paper, we propose to implement an adaptive control system for T-Flex that actively assists dorsiflexion and plantar flexion of the foot during gait phases. The proposed control system makes the ankle to follow a pre-defined trajectory using clinical tests, adjusting the controller parameters based on the performance evaluation of the previous step and the reference trajectory, to update the orthosis assistance. This approach allows the conditions of the ankle/orthosis system, and the specific parameters of each patient, don't to drastically affect the correct operation of the orthosis, and optimal support can be achieved for patients with gait disorders.