AssistOn-Gait: An overground gait trainer with an active pelvis-hip exoskeleton

We propose AssistOn-Gait, a robot-assisted gait and balance trainer, for restoration and improvement of gait and balance of patients with disabilities affecting their lower extremities. In addition to overground gait and balance training, pelvis-hip exercises aimed to correct compensatory movements arising from abnormal gait patterns can be delivered with AssistOn-Gait, extending the type of therapies that can be administered using lower extremity exoskeletons. AssistOn-Gait consists of an active, self-aligning pelvis-hip exoskeleton supported by a series elastic holonomic mobile platform. The series elastic mobile platform enables compensation of the robot dynamics for transparent operation, while also allowing patients to start/stop motion, vary their speed, sidestep to maintain balance and turn to change walking direction. The pelvis-hip exoskeleton can independently actuate 6 degrees of freedom: the hip rotations in the sagittal plane, the pelvic rotation in the transverse plane, the pelvic tilt in the coronal plane, the lateral and the vertical pelvic displacements. Thanks to its backdriveable design, automatically adjusting the center of rotation of its joint axes, the self-aligning exoskeleton enables an ideal match between the hip rotation axes and the device axes, and can do so while allowing for the natural pelvic movements during walking. This feature not only guarantees ergonomy but also extends the usable range of motion of the hip joints.