High-efficiency inspecting method for mobile robots based on task planning for heat transfer tubes in a steam generator

Many heat transfer tubes are distributed on the tube plates of a steam generator that requires periodic inspection by robots.Existing inspection robots are usually involved in issues:Robots with manipulators need complicated installation due to their fixed base;tube mobile robots suffer from low running efficiency because of their structural restricts.Since there are thousands of tubes to be checked,task planning is essential to guarantee the precise,orderly,and efficient inspection process.Most in-service robots check the task tubes using row-by-row and column-bycolumn planning.This leads to unnecessary inspections,resulting in a long shutdown and affecting the regular operation of a nuclear power plant.Therefore,this paper introduces the structure and control system of a dexterous robot and proposes a task planning method.This method proceeds into three steps:task allocation,base position search,and sequence planning.To allocate the task regions,this method calculates the tool work matrix and proposes a criterion to evaluate a sub-region.And then all tasks contained in the sub-region are considered globally to search the base positions.Lastly,we apply an improved ant colony algorithm for base sequence planning and determine the inspection orders according to the planned path.We validated the optimized algorithm by conducting task planning experiments using our robot on a tube sheet.The results show that the proposed method can accomplish full task coverage with few repetitive or redundant inspections and it increases the efficiency by 33.31% compared to the traditional planning algorithms.

Experimental Study on Frog-inspired Swimming Robot Based on Articulated Pneumatic Soft Actuator

This paper presents a frog-inspired swimming robot based on articulated pneumatic soft actuator.To realize the miniaturization of the robot and enhance its environmental adaptability,combined with the advantages and characteristics of soft materials,an articulated pneumatic soft actuator is designed based on analysis of a frog's propulsion characteristics.A structural model is established to analyse the mechanical properties of the soft actuator.With the goal of making full use of the driving torque of the actuator and enhancing the propulsion efficiency of the robot,the motion trajectories of each joint of the robot are planned.Based on the trajectory planning,the control strategy of the soft actuator is determined to realize the frog-like swimming of the robot.The torso size after assembly is 0.175 m×0.100 m×0.060 m,which realizes the miniaturization of the frog-inspired robot.During the movement of the robot,the torso moves stably and flexibly,and can realize continuous linear and turning movements.The rationality of the structure and trajectory planning are verified by prototype experiments.

Chaotic CPG Based Locomotion Control for Modular Self-reconfigurable Robot

The most important feature of Modular Self-reconfigurable Robot （MSRR） is the adaption to complex environments and changeable tasks. A critical difficulty is that the operator should regulate a large number of control parameters of modules. In this paper, a novel locomotion control model based on chaotic Central Pattern Generator （CPG） is proposed. The chaotic CPG could produce various rhythm signals or chaotic signal only by changing one parameter. Utilizing this characteristic, a unified control model capable of switching variable locomotion patterns or generating chaotic motion for modular self-reconfigurable robot is presented. This model makes MSRR exhibit environmental adaptability. The efficiency of the control model is verified through simulation and experiment of UBot MSRR platform.