| With the construction and development of modern transportation,natural gas,petrochemical and manufacturing plants,pipeline has become an indispensable means of material transportation in modern production and life.Regular inspection,maintenance and cleaning of pipeline is an important link to ensure that pipeline can transport materials normally,but it is not appropriate or impossible to use workers to detect,maintain and clean pipelines for a long time.It is more reasonable,economical,efficient and friendly to use special pipeline robots to monitor,maintain and clean pipelines.Relying on “the research and development of occupational hazard protection technology and equipment for labor-intensive industrial enterprises”(Project No.2016YFC0801700)under the State Key R&D Program.Taking the ventilation and dust removal pipes(480mm~800mm)in the polishing and grinding workshops and other labor-intensive workplaces as the object of operation,According to the requirements of explosion-proof,motion control and cleaning,a pipeline robot which can run independently in the pipeline and carry the cleaning device is developed.The main research contents are as follows:(1)On the basis of consulting and mastering a large number of relevant literature and data of pipeline robot,the characteristics of various walking and driving modes are summarized and analyzed.A two-track pipeline robot driven by pneumatic swing cylinder is proposed.The relevant tracked walking mechanism,the main structure of the robot,the circuit of pneumatic driving system and the general detection and control system are designed.(2)The basic kinematics equations of two tracked pipeline robots are established.The drag effect of towing cables in straight and elbow pipes,and the influence of pipe gradient and robot roll angle on the minimum mass adhesion and traction force required by the towing cables are studied.The dynamic mathematical model of swing cylinder controlled by high-speed on-off valve is studied.The model is composed of flow model of high-speed on-off valve,flow differential equation of swing cylinder and force balance equation of swing cylinder blade.Simcape's simulation model is built based on the theoretical model.It is concluded that the larger the duty cycle,the larger the output angular velocity of the system,and the period has no effect on the steady output angular velocity of the system.(3)The speed characteristics of pipeline robot in the process of bending are analyzed,and the differential speed regulation model of left and right caterpillar wheels is deduced.The speed regulation model is simulated and validated under Adams simulation model.The inaccurate walking control,step speed control and position control of the robot in the pipe are studied.It is concluded that the average speed of the robot can be controlled by the control signal PFM cycle,the step speed and the precise position of the robot can be controlled by the duty cycle of PWM.Fuzzy-PID control is proposed for position control,which has faster response characteristics and better steady-state accuracy than PID control.The control strategy of pipeline robot autonomous walking in pipeline is studied.The fuzzy controller of straight pipe speed regulation and the differential controller of elbow are designed.The joint simulation platform of Adams and Matlab is built,and the control effect of the controller is simulated and verified.(4)Aiming at working requirements and environmental conditions,the software and hardware of the control system of pipeline robot are designed in detail.The humancomputer interface program based on Labview and the multi-task lower computer control program based on UCOS-II real-time operating system are developed.Motion speed test,maximum traction test,climbing test and field measurement were carried out.The results show that the average forward speed of the pipeline robot can be dynamically adjusted between 0 and 19 mm/s.The maximum traction force in the straight pipe is about 195 N,and the maximum steep angle is about 15 degrees. |
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