Characteristic Analysis And Research On Cableless Chain In-pipe Robot Driving Unit

By the application environment and space restrictions, workers can not directly carry out a repair and maintenance operation, and so the gas pipelines are prone to corrosion and breakage. Once the coal gas leak, lots of serious problems will appear such as the loss of life and property, the environmental pollution and so on.As a smart moving platform, in-pipe robot, which can carry sensors, NDT devices and tools for repairing and maintenance to pipelines regularly and extend pipeline service life, has a good prospect.This paper, based on analysis of the principle and the development at home and abroad of the in-pipe robot, has done a design & research job to the robot-driven unit by applying virtual prototyping simulation technology and reliability engineering theory.According to the performance index, this paper accomplished the mechanism design to the driving and detection unit. On the basis of consulting a large amount of technical data and analyzing the existing in-pipe robots, the wheel drive mode and none cable operation method were selected according to the specific environment and inspection operational requirements. Also, designed a spring-screw nut mixed preloading and adjustable mechanism, a spring buffering mechanism and a driving mechanism. Therefore, the proposed robot can have a self-adaption to the environment and avoid the rigid shock, and can be used in inspecting for pipes withΦ270mm~Φ380mm in diameter.Designed and adopted a differential-driven steering mode, which enable the robot a active steering capability. Analyzed the dynamic characteristic of the screw nut vice, and concluded a performance chart. Accomplished the pipeline constraint equation, and at the same time, researched the motion characteristics and mechanical properties of the proposed robot in pipe and analyzed a variety of moving resistance, the results show that the traction force satisfied the request.Established a three-dimensional prototype of the robot by using Pro/E and, through the interface module Mechanism/Pro, done a co-simulation to the driven unit based on Pro/E and ADAMS. According to the results, drew some curves, such as driving wheel diameter vs. robot traction, spring preload vs. robot traction and so on, and realized the optimization to the spring preload, spring stiffness coefficient and screw pitch.Analyzed and researched the driving unit reliability based on fault tree analysis theory. Constructed the system fault tree and its mathematical models,and qualitatively and quantitatively analyzed the fault tree, found out the key weak links affecting the system reliability, which provides a basis for the mechanism design and the physical prototype development.