Systematic Design of a 3-DOF Dual-Segment Continuum Robot for In Situ Maintenance in Nuclear Power Plants

Abstract

In situ maintenance works for nuclear power plants are highly beneficial as they can significantly reduce the current maintenance cycle and cost. However, removing absorber balls in a constrained environment through an inspection port is fairly challenging. In this article, a 3-DOF dual-segment continuum robot system is proposed which is equipped with an end-effector to remove absorber balls by pneumatic conveying. Then, according to the symmetrical layout of actuation ropes, the kinematics of the single-segment continuum robot are extended, and the kinematics equation which is universal to the continuum robot with the dual segment is summarized. In addition, some special kinematics solutions can be obtained according to opposite-bending and feeding characteristics. Finally, the functions of the device are verified by tests. The results show that the continuum robot can smoothly pass through the divider plug and reach any position at the bottom of a ball-storage tank where absorber balls are located with only two segments. In a gas environment, the efficiency of absorber ball removal can reach 58.96 kg/h with a lift of 7.5 m and 48.54 kg/h with a lift of 10 m. This result undoubtedly paves the way for the in-service maintenance of nuclear power plants.

Tendon-Driven Continuum Robots for Aerial Manipulation—A Survey of Fabrication Methods

“…The discrete links with alternating diagonally-aligned joints contribute to the overall arm having high torsional stiffness. Additionally, this design allows for a significant degree of bending at individual links, while maintaining a high load-handling capacity [39,[134][135][136][137][138][139]. Therefore, these types of manipulators are explored for applications beyond the medical field in the realm of continuum manipulators, including aeroengine repair [135], nuclear plant maintenance [136], and aerial manipulators for pick and place operations [39].…”

“…Additionally, this design allows for a significant degree of bending at individual links, while maintaining a high load-handling capacity [39,[134][135][136][137][138][139]. Therefore, these types of manipulators are explored for applications beyond the medical field in the realm of continuum manipulators, including aeroengine repair [135], nuclear plant maintenance [136], and aerial manipulators for pick and place operations [39].…”

“…Some designs choose to place the joints along the centreline of the backbone, resembling vertebrae [39,116], while others prefer to position them at the periphery or outer surface of a tubular-profiled manipulator design [134,136]. In the latter approach, the tendon guides (eyelets) are fashioned either in the form of welded guide rings radially attached to the joint supports [134,136], or as guide holes (eyelets) created on disks inserted at equal intervals throughout the manipulator. Conversely, the centreline-based joints method features radially extended flange/disk profiles around each joint, providing eyelets for routing the tendons [39,116,137].…”

“…The tubular-profiled structure offers space not only to accommodate tendons, but also flexible tools, wires, and any other necessary components that need to be taken up to the end of the manipulator without interfering with the outer environment [116,135,136,142]. These include signal/power cords for sensors, light sources, and end effector-actuators.…”

Deep CNN-Based Static Modeling of Soft Robots Utilizing Absolute Nodal Coordinate Formulation

“…Unlike traditional rigid robots, continuum robots can change their forms dynamically, which makes them adept at moving through both tight and unpredictable spaces. This versatility makes them fitting for a range of uses, from inspecting industrial pipelines [6] and aircraft engine upkeep [7] to medical procedures [3,8].…”