Dynamics of the mobile robotic balance trainer: Study of the pentagonal closed chain properties in relation with balance tasks

Balance and gait rehabilitation are the lesser progressed fields in robot aided rehabilitation, mostly due to the complexity of the involved tasks. One of the main problems is the impossibility for most patients to autonomously practice balance and gait rehabilitation safely, especially in the early fundamental stage of recovery. A solution to this limitation of the therapies is to realize a robotic device able to independently support the patient and guarantee the patient´s safety during Activities of Daily Living (ADLs) without interfering with the patient´s motion when support is not needed. In this paper, we propose the design of a pentagonal closed chain theoretically proven to overcome the limitation of the current technologies, which is not able to transparently follow and support the patient during the initialization of gait. The results obtained showed not only that the proposed pentagonal closed chain is able to be transparent to the patient during the initialization of the gait task, but also presents passive dynamical properties that help to support the patient during trajectories which lead him close to his margins of stability.