Research On Screw Drive In-pipe Robot

As one of the important modes for transportation of oil and gas resources,pipe-line has been developed for nearly a hundred years.Since the reform and opening up,China has formed oil and gas pipeline network throughout the country as well as con-nected to foreign countries,among which length of on-land pipelines reaches about 120,000 km,length of urban oil and gas pipelines is as much as 600,000 km.At pre-sent,80%of the long-distance oil and gas pipelines in China have gone into the acci-dent-prone period,high-frequency pipeline leaks and explosion accidents brought huge economic losses.Therefore,carrying out pipeline defects detection is an im-portant means to eliminate security risks and to implement complete pipeline man-agement.At present,intelligent pipe pigs are used to achieve in-pipe testing for large-diameter long-distance pipelines,while appropriate in-pipe testing equipment for small size of the city's oil and gas pipelines still lack.As the urban areas are densely populated,oil and gas pipelines are complex distributed,security risks of oil and gas pipelines may lead to catastrophic accidents.To ensure the safe operation of urban oil/gas pipelines and to avoid the occurrence of catastrophic accidents,it has great significance to carry out suitable equipment for urban oil and gas pipeline test-ing and maintenance.In this paper,a series of spiral in-pipe robots are proposed,the basic theories and key technology research of this kind of robot are also carried out.The main research work accomplished in this paper include:(1)Functions and working mechanism research of the existing in-pipe robots are carried out.The concept of spiral drive in-pipe robot is clarified and the structure of the robot is analyzed.According to the drive mode of drive wheel,principles of active and passive spiral drive in-pipe robot are discussed respectively.Drive spiral angles of the spiral drive in-pipe robot are researched,definition of the drive spiral angle is given,the relationship model of the drive spiral angles and the pipe diameter as well as structural parameters of robot model are constructed.This model is important the-oretical foundation of the pipeline robot mechanism.(2)Motion behaviors of spiral drive in-pipe robot are studied.Kinematics model of both the straight pipe and the elbow pipe of the spiral drive in-pipe robot are estab-lished.Influencing factors of the spiral drive in-pipe robot turning the elbow pipe are studied,and the theory of the variable spiral angles turning and its realization are put forwarded.The analysis shows that the in-pipe robot has a smaller internal friction and a smooth motion with variable spiral angles turning.The kinematic model of the obstacle barrier of the spiral drive in-pipe robot is established,and the obstacle of the main and passive spiral pipe robot is compared and analyzed.The study shows that the active spiral drive in-pipe robot has great obstacle performance.Conclusion of the study provides theoretical bases for the subsequent research of robot's structural de-sign and prototype development.(3)Mechanical behaviors of the spiral drive in-pipe robot are studied.Traction analysis model of the spiral drive in-pipe robot is established,and the simulation analysis of the traction characteristics of the spiral drive in-pipe robot is carried out.The correctness and validity of the traction analysis model are verified by theoretical modeling and simulation analysis,and the regulation revealing that the traction force of the spiral drive in-pipe robot varies with the helix angle change is discovered.In addition,a new type of peristaltic spiral drive in-pipe robot is developed,and speed control model of the robot is studied.Characteristic of the robot's motion changing with the sine function is proposed.Traction characteristics of the peristaltic spiral drive in-pipe robot under the sinusoidal variation rule are studied.(4)Structure design of the active spiral drive in-pipe robot is completed.Com-bined with the requirements of the motion and dynamic performance of the spiral in-pipe robot,the functional principle design and structural design of the spiral pipe robot transmission system,the support system and the control system are carried out.On the basis of the above research,based on the idea of planetary wheel drive will drive the wheel and pipeline integration constitute the planetary transmission system,to achieve the active spiral pipe robot,modular active spiral pipe robot structure is designed.Aiming at the shortcomings of the passive spiral drive in-pipe robot,such as easy skidding and poor obstacle performance,a new type of tracked spiral drive in-pipe robot is proposed and developed.Based on the principle of bionics,the movement of the peristaltic creature is simulated,and the peristaltic spiral drive in-pipe robot is put forwarded.The prototype of the peristaltic in-pipe robot is devel-oped.(5)Performance experimental study of the spiral in-pipe robot is conducted.Ac-cording to experimental purposes,experimental equipment and scheme are devised.Traction analysis model of the spiral in-pipe robot is established,regulation of the traction force of the spiral in-pipe robot varies with the helix angle change is revealed.The advantages of the active spiral drive in-pipe robot relative to the passive spiral drive in-pipe robot are demonstrated,and correctness of the spiral drive in-pipe robot traction analysis model is verified.Verifying test of the variable helix angle turning theory is conducted.The experimental results show that the applicability and effec-tiveness of the variable helix angle turning theory and the variable helix angle spiral drive in-pipe robot has good turning performance.(6)Application research of spiral drive in-pipe robot is carried out.Combined with the working characteristics and performance advantages of spiral drive in-pipe robot,the advantages of spiral in-pipe robot in pipe inspection and maintenance are put forwarded.Research focus on the spiral in-pipe robot application in pipeline,and the spiral measuring theory is proposed.The spiral measuring device is developed.Based on these work,the simulation analysis and experimental study are carried out.The results show that spiral drive in-pipe robots used for measurement of pipelines has feasibility and superiority advantages.Based on the research,traction force analysis model of the spiral in-pipe robot is established.The variable helix angle turning theory,the active spiral drive theory and the spiral measurement theory are put forwarded to form the mechanical behavior and the motion behavior analysis method of the spiral drive in-pipe robot.A series of spi-ral drive in-pipe robot prototypes are manufactured,superiority of the proposed robot in pipeline operations is demonstrated.The research results provide a new theory and method for the field of pipeline robot,and the developed pipeline robot has a favora-ble application prospect in pipeline inspection and maintenance field.