Caster Walker GAIT Trainer (CGT): A robotic assistive device

Stroke has become one of the leading causes of lower limb paresis. Costing the patients, a fortune for its diagnosis and prognosis. Clinical experimentations have proven that one can regain ambulation if the rehabilitation is started in the acute or sub-acute stage. Traditional mode of rehabilitation include manual therapies which are labor-intensive and time consuming. Therefore, robotic training are preferred over manual therapies. Nevertheless, there are some limitations such as devices are bulky and complex, some are not portable, others need body weight support system, and costly. To address such issues, this paper proposes development of a new Caster Walker Gait Trainer (CGT) for gait rehabilitation. CGT is an end-effector based passive device in which Stephenson III six-bar linkage has been implemented to mimic the kinematics of a healthy gait. The trainer device uses a belt-pulley system for providing motion to the linkage. The lower limb of the patient gets the drive as he/she pushes the cater walker forward or backward. The paper also proposed the optimal design of defect-free Stephenson III six-bar linkage using loop-by-loop approach. To design the linkage, an optimal problem is formulated, and tear drop ankle trajectory is desired. The optimization problem is solved using a nature-inspired algorithm and it is found that the trajectory generated by the synthesized mechanism is able to mimic the desired trajectory. Then using the notion of inverse kinematics, hip and knee trajectories are obtained from the generated ankle trajectory for validation.