Kinematic evaluation of mobile robotic platforms for overground gait neurorehabilitation

Gait assistive devices offer a great solution to the walking re-education which reduce patients theoretical limit by aiding the anatomical joints to be in line with the rehabilitation session. Overground gait training, which is differs significantly from body-weight supported treadmill training in many aspects, essentially consists of a mobile robotic base to support the subject securely (usually with overhead harness) while its motion and orientation is controlled seamlessly to facilitate subjects free movement. In this study, efforts have been made for evaluation of both holonomic and nonholonomic drives, the outcome of which may constitute the primarily results to the effective approach in designing a robotic platform for the mobile rehabilitation robot. The sets of kinematic equations are derived using typical geometries of two different drives. The results indicate that omnidirectional mecanum wheel platform is capable for more sophisticated discipline. Although the differential drive platform happens to be more simple and easy to construct, but it is less desirable as it has limited number of motions applicable to the system. The omnidirectional robot consisting of mecanum wheels, which is classified as holonomic is potentially the best solution in terms of its capability to move in arbitrary direction without concerning the changing of wheel's direction.