Design and analysis of a pipeline robot with the function of differential movement

A wheel-type pipeline robot with the ability of environment self-adaptation and the function of differential movement is developed, which can regulate the speeds of driving wheels automatically by using the tri-axial differential mechanism and improve the locomotion compliance of the robot when getting across the elbow. To analyze the differential effectiveness of the robot, an exactitude pose model of the robot in elbow is established, which makes it possible to calculate position of the wheel centers and the contact points. Based on the pose model, the theoretical speed ratios of the driving wheels can be computed easily. Also the normal force generated between the driving wheel and the pipeline wall is studied, and the model of the traction force of the robot is established. Several experiments of differential and traction force are accomplished, and the test results are consistent with the theoretical analysis. So the tri-axial pipeline robot possesses outstanding ability of moving in elbow and is suitable for application in the project pipelines.