Powered Super Tail: A Terrain-Adaptive Wheel-legged Robotic Limb to Assist Human’s Load Carriage

摘要

Load carriage is a common demand in humans’ daily life. Long time load carriage often causes significant energy expenditure for the body and may even bring physical problems like muscle strain. Variations in terrains and ground conditions are usually inevitable in such scenarios, which disrupts humans’ gait and leads to even more energy expenditure. In this paper, a wheel-legged robotic limb, Powered Super Tail (PST) to assist human’s load carriage in varying terrains and ground conditions is proposed. The PST system mainly consists of a support rod transferring load to the ground and a pair of stepping triple wheel groups adaptable to different terrain conditions including ground barriers, stairs and rough roads. Driven by a pair of motors, uplifting support for the load and appropriate force assistance could be effectively provided by the support rod, and thus energy expenditure of human body could be reduced. The system’s performance on human body was tested. It is shown that the stepping triple wheel group could successfully traverse barriers of different heights and ascend stairs. The effect of the system on human body standing and walking on flat ground were respectively evaluated under three experimental conditions including 1) with the load only (LOAD, 16.42 kg); 2) with the powered PST (PST_ON, 27.30 kg); 3) with unpowered PST (PST_OFF, 27.30 kg). And the percentage of metabolic power consumption reduction was the metric for evaluation. Experiments demonstrate the following results: during standing, the metabolic power consumption under PST_ON is lowered by 5.42% compared to LOAD and 12.56% compared to PST_OFF; and during walking, the metabolic power consumption is lowered by 20.85% compared to LOAD and 36.58% compared to PST_OFF.