The Design and Control of a New Lower Limb Rehabilitation Robot for Active and Active-assisted Exercises

Yılmaz C., Budaklı M. T., Bağcı F.

Euroasia Journal of Mathematics, Engineering, Natural & Medical Sciences, vol.10, no.31, pp.66-91, 2023 (Peer-Reviewed Journal)


The high position accuracy and rigidity of robots are very important in interventions to the human body. Due to its closed chain kinematic structure, parallel robots exhibit superior positioning accuracy and rigid body structure. Although these reasons lead to the preference of rehabilitation robots, the closed chain kinematic structure introduces a limited working space which restricts the robot to perform the necessary rehabilitation exercises through one joint, solely. Based on this fact, a newly constructed rehabilitation robot ensuring the same positioning accuracy of a parallel robot and also an increased working space has been utilized in this work. This rehabilitation robot represents a parallel robot as a Stewart Platform structure including a 7th linear actuator combined with a trajectory stabilizer. By means of its expanded working space, this robot system offers the possibility of rehabilitation in the ankle with plantarflexion-dorsiflexion, eversion-inversion, adduction-abduction and in the knee joint with extension-flexion ROMs. On these joints, active and active-assisted ROM rehabilitation with position-based impedance control structure have been applied. Measurements performed on two healthy volunteers revealed that the robot's standard ROM values could be brought with a maximum deviation of 1.3%, with the force or torque occurring in the “0” or reverse direction.