Mechanism Design And Analysis Of Soft Robot For Crack Detection Of Steam Turbine Blades

About 80% of the electricity in the world is generated by steam turbines.Once the steam turbine fails,it needs to be out of the cylinder for maintenance,which takes a long time and costs a lot.The internal blades of the steam turbines are densely packed and have different curvatures,which cannot be accessed by traditional rigid robots.Based on the crawling robots,in order to detect the blade cracks in the steam turbines without opening the cylinder,so as to greatly reduce the maintenance cost.The main research contents of this paper are as follows:It mainly includes wiring scheme and mechanical analysis of flat spring of drive unit,ABAQUS simulation and experimental demonstration,structural design and soft robotic kinematics solution.The details are as follows:Firstly,according to the distribution of steam turbine blades,we determine the robot’s flat body shape,and select the wire-spring drive form with two drive units connected in series,and the kinematics and mechanics of the drive unit are studied.for the flat spring of the drive module of the wall-climbing robot,In order to achieve better pitch and yaw motion,the geometric theory is used to analyze the relationship between the flat spring wiring position,the number and spacing of the wiring,and the length,width,and height of the spring.The simulation experiments were carried out in the MATLAB environment to demonstrate the better wiring scheme,the number of wires and the size of the spring to better guide the structural design.And the relationship between the deformation and displacement of the flat spring under transverse and longitudinal loads is theoretically analyzed.Based on the theoretical analysis of the drive unit,we carry out the simulation and experimental research on the drive unit.Through the ABAQUS simulation software,using the slip ring constraint,the stiffness of the flat spring with the same size is verified by simulation and the influence of different threading schemes on the flat motion deformation under the pitch and yaw motion is analyzed.Then an experimental platform was built to test the relationship between the bending angle,displacement and force change of pitch and yaw motions under different number of threading schemes.The conclusion is compared with the previous geometric method and simulation to demonstrate the accuracy and we explore the reasons for the difference,and the conclusion is guided the realization of the required movement posture and trajectory under a smaller force.The experimental results show that the number of threading has basically no effect on the yaw motion.Under the condition of satisfying the motion attitude,the less the number of threading is,the easier it is to realize the pitching motion.On the basis of drive unit theory and experimental research,we complete the overall structure design of the robot.We analyze the overall size of the steam turbine blades,the areas to be detected and the most dangerous areas,and we determine the overall size of the soft robot.Then,we select the appropriate adsorption mode,movement mode and drive mode to design the overall structure of the line-driven soft robotic.We design the pre-bent flat spring,so that the soft robotic can reach the required motion angle and motion range during the motion process,and finally we check and calculate the weak part of the rigid body.Finally,according to the motion characteristics of the line-driven robotic,we analyze the geometric kinematics of the two-stage robot,and analyze the forward and inverse kinematics between the driving space.And we analyze the range of motion of the robot’s head to provide theoretical guidance for robot motion planning and accurate control of the robot’s feet.