Haptic devices are widely used as control interfaces for robotic teleoperation, offering intuitive rendering of interactions between remote robot and environment. In particular, cutaneous feedback devices provide intrinsic stability and reduced form factor compared to kinesthetic feedback interfaces. However, the implementation of cutaneous feedback devices in industrial settings must be rigorously validated to prevent potential equipment accidents, which could lead to substantial economic losses due to unskilled robot manipulation. This paper presents a novel ungrounded haptic control interface (POstick-VF), designed specifically for high-risk steel production tasks. POstick-VF offers visuo-tactile feedback within an extensive workspace, enabling intuitive robot manipulation through its kinematic similarity with real tools ensuring safety. The performance of the developed POstick is rigorously validated and compared with conventional joystick controller through experiments conducted with an on-site hydraulic robot.

The implementation of digital twins (DTs) in industrial environments poses significant challenges, especially for tasks requiring direct physical interaction. This is critical in high-risk environments where system failures can lead to severe human and economic losses, and where even minor errors can have catastrophic consequences. Traditional robotic teleoperation systems often lack intuitive control and require extensive training, increasing the risk of malfunction and accident. This study addresses these challenges by introducing DT-based teleoperation for steel production, focusing on the hazardous lump iron removal process. We present two novel haptic interfaces: POstick-KF, offering enhanced kinesthetic feedback, and POstick-VF, providing a larger workspace with visuo-tactile feedback. These interfaces are designed to mimic real tools, ensuring intuitive control and quick operator training. A user study shows that POstick-VF significantly improves tracking accuracy for novices, while POstick-KF excels in interaction performance regardless of experience. In particular, POstick-VF improves interaction skills over time, and achieves comparable performance to POstick-KF, but with a simpler system. These interfaces have been rigorously tested to ensure robustness and are currently undergoing field testing for real-world applications. Our findings highlight the potential of these haptic devices to achieve the safety and efficiency of DT-based teleoperation within high-risk industrial environments, marking a significant advance in the field.

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.

This paper proposes a passivity-based nonlinear disturbance observer (DOB) design for a powered upper-limb robot control. The proposed DOB allows for the nonlinearities of the robot dynamics, whereas the typical DOB designs cannot. Moreover, by virtue of the passivity property, human operator and environmental interactions can be embedded in the control loop. As a DOB, the proposed approach has a disturbance observation property that makes the actual robot behave like a nominal model selected by the user. Performance analysis proposes a gain tuning rule. In experimental validation, actual powered upper-limb robot is used to perform unknown payload carrying applications.