Adaptive Haptic Control Interface for Safeguarding Robotic Teleoperation in Hazardous Steelmaking Environments

Steel mill is one of the most extreme and hazardous working environments due to molten iron erupted from blast furnace. Current manual labor to remove lump iron near the outlet, which is essential to prevent lump iron from scattering or blocking of molten iron, is performed by equipped human workers using a long stick tool. Thus, implementation of robotic teleoperation system is in demand to ensure the safety of workers. However, the conventional command interface is not intuitive for tool manipulation (i.e. pivoting, sweeping). Besides, haptic interface, which is used to render interaction results efficiently, still limits performance due to narrow workspace and insufficient kinesthetic feedback output compared to requirements. This paper proposes a novel haptic command interface (POstick) specified to lump iron removal task with two types (KF and VF). Both POsticks have rod-shaped end tip which is identical to actual tool already used to accelerate training. POstick-KF has large workspace and high kinesthetic feedback output satisfying requirements. Further, POstick-VF has strength with unlimited workspace at the expense of the amount of haptic information from simple vibrotactile feedback. User study to compare the performance of POsticks and conventional interface reveals that POstick-KF and VF showed superior interaction and tracking ability, respectively. Moreover, these two properties are in trade-off relationship that cannot be compatible. Finally, we proposed a seamless and automatic conversion mechanism from POstick-VF to KF, and vice versa, to cover up inherent limits of haptic devices.