Research On Bridge Bottom Crack Detection Platform Based On Tethered Flying Climbing Robot

Crack detection at the bottom of the bridge is a necessary means to detect the health status of the bridge structure and prevent major traffic accidents such as bridge collapse.Preventive maintenance of the bridge based on the test results can protect the lives and property of the people to the greatest extent.Aiming at the problems of low precision,low efficiency and lane occupation in the current bridge bottom detection technology,a tethered flying climbing robot platform for bridge bottom crack detection is designed and developed.By carrying the detection unit,it is expected to obtain efficient and global automatic detection of bridge bottom cracks.The research object of this paper is the bridge bottom crack detection platform of tethered flying-climbing robot.Through the analysis and research of the flight control technology principle of tethered aircraft,an innovative detection method of bridge bottom crack based on tethered flying-climbing robot is proposed.The key technologies such as mechanical structure,kinematics model,flight control algorithm,bridge image transmission and processing technology of the flying climbing robot are studied.The automatic acquisition device of bridge bottom crack based on FPGA is designed,and the feasibility of this paper is verified by experimental analysis.In the process of studying the bridge bottom detection robot platform,firstly,the power supply system and mechanical structure of the traditional four-rotor UAV structure are reformed,and the innovative structure of the tethered flying-climbing robot is proposed.Through the analysis of the basic flight principle of the flying-climbing robot,the coupling force between the robot body structure and the tethered cable,and the modeling of its motion process,the flight control algorithm is optimized,thereby improving the flight stability of the special-shaped aircraft.Next,the principle of motion control algorithm of position loop and attitude loop is studied in detail.The optical flow displacement and acceleration displacement are fused to realize the position estimation of the robot.The position loop double closed-loop PID control is carried out by using the estimation results to obtain the desired attitude and realize the stable and efficient control of the robot position.For the robot attitude control,the stable control of the robot attitude is realized by the double closed-loop PID control algorithm,and the antiinterference performance of the robot in the complex environment is increased.Then the optimized flight control algorithm is transplanted to the FPGA platform according to the algorithm principle,and the FPGA flight controller is constructed.Then,the optical fiber transmission and processing algorithm of FPGA high-definition image is studied,and the photoelectric Ethernet data conversion is realized by using its excellent high-speed pipeline and parallel data processing ability.After using FPGA to filter the image data and other preprocessing work,the crack area is extracted by image segmentation algorithm,and the connected domain of the binary image is processed to locate the position of the crack,which reduces the image processing pressure of the ground workstation computer.Finally,by constructing the robot prototype and designing the host computer software,the stable flight of the robot is realized after the PID parameters of the flight control are adjusted,and then the image data acquisition and transmission are completed by the optical fiber Ethernet channel,which provides support for the image processing on the software side,and verifies the feasibility and stability of the system.