Research On Structure Design And Motion Characteristics Of Mechanical Differential Pipeline Robot

Pipeline robot is a special robot that can walk along the inside of the pipeline and inspect the inside of the pipeline.Because of its good pipe diameter adaptability and passability,it replaces manual maintenance and becomes the preferred tool for pipeline maintenance.However,when the pipeline robot overhauls the pipeline with complicated arrangement and multiple turns,the actual contact track length between each driving wheel of the robot and the inner wall of the pipeline is different,which leads to slippage between the driving wheel and the inner wall of the pipeline driven by the same speed,resulting in redundant wear.Therefore,it is of great significance to realize the differential function of each driving wheel of the pipeline robot.Pipeline robot has the function of differential speed,which is mainly to meet the requirements of obstacles when going straight inside the pipeline and different speeds of driving wheels when turning.In this paper,based on the functional principle of planetary gear differential,a mechanical differential pipeline robot with 90° staggered symmetry in front and back structure is designed,which is suitable for the inner diameter of small and medium-sized pipelines.The robot is divided into five functional modules,and the mechanism types of each functional module are compared and optimized to determine the specific structure and parameters.After establishing the mechanical analysis model of the support structure and calculating the overall transmission ratio of the robot,the selection of the driving motor is completed.And the 3D model of the robot is drawn by Solidworks software.Then the motion characteristics of the pipeline robot in the pipe are analyzed,including the requirements of the geometric size when passing through the bend and the division of the robot's bending stage.The contact point between the robot driving wheel and the inner wall of the pipeline is described by coordinate transformation method,and the variation law of the driving wheel speed and related influencing parameters is expounded.The obstacle-surmounting ability and influencing factors of robot in different environments are analyzed theoretically.The virtual prototype of the pipeline robot is simulated and analyzed in ADAMS software.Motion pairs are added to each part in the 3D model of the robot to create the association.The walking process of the robot under different environmental conditions is simulated and the simulation data of the robot's traction force,obstacle surpassing ability,diameter changing ability and differential speed ability are obtained successively,and the simulation data are in good agreement with the theoretical analysis.Finally,the in-pipe walking experiment of pipeline robot prototype is carried out.Before the test,the hardware connection and application of the control system are introduced.After that,the physical prototype of the robot is made and the walking test is carried out in different pipeline environments.The experimental results show that the robot can pass the horizontal,vertical and 90° elbow smoothly,and has the adaptive differential function,which meets the design requirements.