| Pipes are widely used in drainage,natural gas transportation and other industrial fields.After a period of time,pipelines are easily corroded to produce cracks and other defects.In order to ensure the safe transport of pipelines,it is necessary to regularly detect and maintain pipelines.As the manual detection method is inefficient and labor intensity,the method of detecting defects in the inner surface of the pipeline by using the pipeline robot has become the mainstream method.Images of the damaged area in the pipeline are collected by the camera that the robot carries.Analysis and identification of pipeline images are implemented based on image processing technology.The mechanical structure and motion control of pipeline robot,the method of pipeline crack detection were studied.The main contents are as follows:The mechanical structure of the pipe inspection robot is designed,including the walking mechanism,the pipe diameter adapting mechanism,the lifting mechanism,the PTZ rotating and pitching mechanism,etc.The virtual prototype model of the pipeline robot is simulated by using ADAMS software.The DC motor is used to drive the track wheel.The adjustment mechanism is designed to adjust the angle between the two track wheels,so that the pipe robot can work in pipes with diameters ranging from 400 mm to 800 mm.A stepper motor is used to control the motion of the lifting mechanism,so that the PTZ can be adjusted within a certain range of height and accurately positioned.A stepper motor and a steering gear are used to respectively control the rotating and pitching motion of the PTZ,so that the camera can record the situation within the pipe in all directions.The virtual prototype model of the pipeline robot is builded by utilizing CATIA software,and it is imported into ADAMS software.The virtual prototype simulation model of the pipeline robot is established by adding restraint and setting the driving parameter,and it is simulated by using ADAMS software.The simulation results show that the pipeline robot can meet the design requirements.A control system of the pipeline robot based on ARM chip STM32F103ZET6 is designed.The hardware circuit of the control system mainly includes power circuit,motor drive circuit and so on.The motion control program of the walking mechanism,the lifting mechanism,the PTZ rotating and pitching mechanism is written by using Keil uVison4 software.The interface of control system is written in the environment of Microsoft Visual Studio 2010.The host computer is used to send control instructions to the microcontroller through the bus communication system.The microcontroller is used to receive instructions to control the movement of the robot,the motion of the lifting mechanism,the rotating and pitching motion of the PTZ,etc.A user-friendly image processing system for pipeline crack detecting is developed based on open computer vision library.A novel method for pipeline crack detecting based on image processing technology is proposed,which realizes the identification of pipeline cracks and the extraction of parameters such as areas and lengths of cracks.With the advantages of simple operation and strong interaction,the image processing system can select and enlarge the crack area of the image,easy to the analysis and processing of the image.Firstly,median filter is used to remove the noise of gray image.The morphological gradient algorithm is also applied to edge detection.Then,the binary image is obtained by applying Otsu algorithm to select the threshold of image segmentation adaptively.Hough transformation is adopted to detect the straight line.Finally,the filled image is obtained by applying morphological method further for the binary image.The skeleton of crack is obtained by applying the refinement algorithm for the filled image.The area and length of the crack are obtained by counting the number of pixels.The experimental results show that the method of pipeline crack detection proposed in this paper is feasible and effective. |
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