Design of a crutch-exoskeleton assisted gait for reducing upper extremity loads✰

Abstract

Objective: An accurate comprehension of upper extremity (UE) loads would provide insights into gait planning for reducing the dependence on crutches/walking frames when walking with robotic exoskeletons. This paper was undertaken to identify the position of the crutch support point and the support leg and design a crutch-exoskeleton gait planning strategy to evaluate system stability and the related upper extremities kinetic characterizations. Methods: Based on the Zero moment point (ZMP) and the static stability criterion of the polygon support model, an adjustable step-length control strategy is proposed to learn how dynamic adjustment changes respond to UE biomechanics. Further-more, the forearm crutches walking test experiment of healthy group is used to verify this strategy. Results: From this experiment, we can see that the control method can display an adaptive step length according to the user's walking state and reduce the load of the upper limbs. Conclusion: The proposed crutch-exoskeleton gait planning strategy would affect the mass distribution of the human-exoskeleton system, further affect the user's upper limb comfort and the distribution of loads in the process of assisted walking. Information about the total load of crutches can help adjust the level of robot assistance, so as to avoid damage to the UE due to overuse or protracted use. Significance: This understanding of UE loads helps to improve the impact of crutches on robot assistance and prevent or minimize UE injury.