Mechanical Design of an Exoskeleton with Joint-Aligning Mechanism for Children with Cerebral Palsy

Effective rehabilitation treatment is crucial for children with cerebral palsy to maintain their mobility while growing up. However, conventional interventions like passive orthosis do not sufficiently relieve pathological gait in most patients. In recent years, motorized exoskeletons showed great success in the rehabilitation of stroke and paralyzed patient and they also give a promising opportunity to the treatment of cerebral palsy. However, the rapid growth rate and morphological variation among children with cerebral palsy bring a great challenge to the structure design. In this paper, the mechanical structure of an adjustable lower-limb exoskeleton is designed for children with cerebral palsy. In order to have general applicability for users with different sizes, this exoskeleton can change its frame lengths to adapt to the height of children from eight to twelve years old. Besides, for having the kinematic compatibility, it also has a joint-aligning mechanism that lets the exoskeleton's hip joint comply with the natural hip internal/external rotation. Simulation is conducted for verifying the kinematics of the exoskeleton and comparison is made between the one with/without the joint-aligning mechanism for studying its effectiveness. Results show that the extra torque due to the hip joint misalignment is eliminated.