The principle of CCTV pipe robot:

In 70s, the development of petroleum, chemical industry, natural gas and nuclear industry and the need for pipeline maintenance stimulated the research of robot in the pipeline. It is generally believed that the J. VR`ERTUT of France first launched the research on the theory and prototype of the robot inside the pipe. In 1978, he proposed the model of the wheel legged inner pipe walking mechanism. In 80s, Fukuda Toshio, Xi Bei Ying Shi, Okada Tokuji, Ma Yuki and Fukuda Ryoji of Japan made full use of the research results and modern technology of the law, the United States and other countries, and developed many kinds of inner tube robots in the structure. Natural gas was developed by Hyouk R. C. of Han Guocheng University." style="box-sizing: border-box">Pipe inspection robot MRINSPECT series. The research of robot technology in China has been over 20 years ago. The research work of Harbin Institute of Technology, the Shenyang Institute of automation, Chinese Academy of Sciences, Shanghai Jiao Tong University, Tsinghua University, Zhejiang University, Tsinghua University, China, Daqing, Petroleum Administration, Shengli Oilfield, Zhongyuan oil field and other units carried out research work in this field. For the research of pipeline robot, there are many researches on multi wheel support structure before, so that the traditional wheeled mobile robot is directly used in the detection and maintenance of circular pipes. When the wheel of a multi wheeled robot is in contact with the wall, the connection between the contact point and the wheel core is in the radial direction of the cylinder, and the direction of the wheel is parallel to the bus bar of the cylinder. This is a special case of the single wheel's upper position in the pipe surface. When the wheeled mobile robot is running in the pipeline, the position and posture of each wheel of the wheeled mobile robot in the pipeline is unpredictable due to the size of the pipe, the curve and the "T" joint. The axis direction of the wheel may not be perpendicular to the radius of the circular tube, so it is necessary to analyze the single wheel on any surface of the pipe surface to satisfy pure rolling and no sideslip. Kinematic characteristics under conditions. For the wheeled pipe robot in the actual application process, such as in the elbow and irregular pipes, the motion interference occurs. Due to the lack of driving force caused by internal friction, because of the deformation of the wall and the error of the robot itself, the robot can deviate from the correct posture, even rollover and block in the pipeline. Researchers at home and abroad mainly solve problems in terms of structure, such as differential, flexible connection, etc., but this will make the structure more complex and increase the cost.

For wheeled pipe robot, accurate kinematic model is the basis for accurate motion control. The kinematics and control theory of a single wheeled and wheeled mobile robot on the pipe surface are very few. It is necessary to set up a set of theories about the kinematics of wheeled pipe robot.
Campion et al. On the basis of previous research results, the kinematics and dynamics models of wheeled mobile robots on horizontal road surface are analyzed. Four state space models are summarized: two pose kinematics model, configuration kinematics model, pose dynamics model, and configuration dynamics model. Karl Iagnemma et al analyzed the various contact situations between wheels and the ground when the wheels and the ground were not rigid, and when the ground was irregular. However, the above model assumes that the wheel and the ground are not deformable, and the ground is a regular horizontal road surface. When a wheeled mobile robot is running in a circular tube, because the environment inside the circular tube is a three-dimensional curved surface environment, the wheeled mobile robot actually operates on a curved surface, so the above model can not be applied to the wheeled mobile robot in a circular tube.
Because wheel cleaning robot operates in three dimensional space when it runs in a circular pipe, its kinematic model is totally different from that of a wheeled mobile robot on the plane. Under the premise of geometric constraint and speed constraint, the relationship between the control input of mobile wheeled mobile robot and the change of robot posture and coordinates is analyzed, and its kinematics model is established. Recently, the research focus of wheeled pipe robot at home and abroad is mainly to improve controllability and controllability of wheeled pipe robot, and the robot develops towards the direction of autonomous operation.Although many scholars have improved the performance of robots from the aspect of structure, there is no systematic analysis of the motion control theory of wheeled mobile robots in circular tubes. Therefore, we need to design the corresponding algorithm according to the kinematics model, so that the robot can achieve stable control in the circle to meet the needs of engineering application.
For wheeled drainpipe robot, besides the structural design and material selection, the main scientific problem is to establish the kinematics model of wheeled robot in the circular pipe, and design corresponding control algorithm, so that the robot can run autonomously, and also can control its horizontal driving operation according to the gesture information, without lateral rollover and card operation. Death and driving force are not enough, so it has good controllability.
In order to establish the kinematic model of wheeled robot in a circular pipe, the following 4 problems should be solved and the corresponding motion control algorithm should be designed theoretically.
(1) the instantaneous speed of the wheel center of a single wheel in any position and position on the pipe surface. The scientific problem of the kinematic characteristics of a single wheel in the pipeline is the description of its position and position and the speed of its wheel core satisfying the condition of pure rolling and no sideslip.
(2) analyze the geometric constraints of wheeled mobile robots on the pipe surface, and deduce the relationship between 6 pose coordinates.
Wheeled robot runs in a three-dimensional cylindrical environment in the pipeline, and its pose coordinates change from the 3 dimension on the plane to the 6 dimension of the space. But because the robot has a specific geometric constraint when running in the pipeline, the 6 pose coordinates of tY are not independent of each other, so it is necessary to deduce the relationship between the 6 pose coordinates.
(3) establish the kinematic model of wheeled mobile robot on the circular pipe surface. The difficulty of deriving the kinematic model is how to establish the relationship between the control rate and the change rate of position and posture coordinates. The control input directly affects the speed of the wheel core, and the wheel center determines the speed of the robot's rigid body, so it is necessary to analyze the relationship between the rigid body of the robot and the speed of the wheel core. The essence of this problem is to deduce the relationship between instantaneous screw motion parameters and control input, and the relationship between the pose change rate of the robot and the control input.
(4) according to the kinematic model and operation requirements, the corresponding control rate is designed to keep the robot running in a horizontal direction. According to the established kinematic model, the attitude angle is taken as the state variable, and the corresponding control rate is designed through the feedback of the attitude sensor, so that the robot can run in accordance with the required attitude in the pipeline. The kinematic model is mainly used to design the control ratio and to analyze the stability of Lee Yap Andrianof's (Lyapunov) function.