Biomechanical Joint Design of Patient-Specific Rehabilitative Knee Exoskeletons for Misalignment Correction

Wearable robots, or exoskeletons, are solutions for rehabilitation and assisted motion. One of the challenges in designing a patient-specific knee exoskeleton is the complexity of the human knee joint. A single revolute joint cannot fully mimic the motion of a human knee, potentially causing misalignment between the exoskeleton and the human limbs. This human-exoskeleton misalignment then generates undesired interaction forces onto human limbs and hinders the agility of movement. This paper introduces a novel approach to designing a patient-specific biomechanical knee joint with a grooved cam. The joint design uses motion capture data of individual patients to generate cam profiles that allow for simultaneous rotational and translational motion in the designed system. Two biomechanical joints were designed for two subjects using the proposed design method. The designed cam joints were experimentally evaluated against a single-degree-of-freedom knee joint on both subjects as a proof of concept. The results demonstrate that the cam profiles were adequately generated, and the resulting joints effectively reduce misalignment compared to a single revolute joint.