Blending control method of lower limb exoskeleton toward tripping-free stair climbing

Tripping frequently occurs when an individual climbs the stairs with improper foot clearance. Among older adults, falling down the stairs accounts for over 10% of accidental deaths. This paper proposes an exoskeleton control method that blends human-dominant and exoskeleton-dominant control to prevent tripping. The blending controller not only allows the exoskeleton to track the pilot's movements and provide power assistance during regular walking, but also allows the exoskeleton to help the pilot avoid dangers in some cases. An online path planning method is used to generate a safe trajectory in the exoskeleton-dominant mode to help the pilot correct their running trajectory. The controller provides the pilot with adjustment spaces to adapt to sudden changes in the motion mode and enable active self-regulation. The simulations verified the effectiveness of the proposed blending method. Experiments showed that the robot should be involved in the pilot's movements when the foot clearance exceed the safety threshold to prevent tripping.