A Bidirectional Human-Machine Control Interface Based on Virtual Fixtures for Safe Teleoperation of Hyper-Redundant Robots

Abstract

In confined and hazardous environments where human access is severely limited, hyper-redundant manipulators play a crucial role in preserving operator safety and mitigating operational risks. Their numerous degrees of freedom and compact design make them particularly well-suited in the context of nuclear fusion reactors, whose distinct geometry, restricted spaces and heavy loads to be handled, pose unique challenges that conventional manipulators struggle to overcome. This paper proposes a bidirectional control interface for the teleoperation of hyper-redundant robots, with an application to the inspection and maintenance of magnetic fusion reactors. The proposed strategy provides the operator with an intuitive interface and optimises the robot configuration while reducing unnecessary moments of its bulky parts, which may impact the overall system performance and operation safety. It includes two control modes: position and velocity control, which can be selected based on the operator’s preferences. Additionally, the strategy integrates Virtual Fixtures (VFs) in both master and slave control to provide haptic feedback and prevent the slave robot from reaching singular configurations, joint and torque limits, or colliding with the environment. Tests were performed on the DTT Hyper-Redundant Manipulator which was teleoperated through a haptic device by 9 volunteers. The achieved results demonstrated that using VFs allows the robot teleoperation more efficiently and effectively, keeping it within the joint position and torque safety ranges and far from forbidden regions of the environment, while concurrently reducing the movement of the bulky parts.

Keywords

• Bilateral teleoperation
• human-machine interface
• hyper-redundant manipulators
• nuclear fusion
• remote handling
• virtual fixtures