| At present,the safety inspection of petrochemical plant equipment,including: fire,pipeline leakage,corrosion,etc.,mainly rely on manual completion.The detection range is wide,the labor cost is high,the all-weather detection can not be realized,and it also has certain harm to the health of workers.Therefore,this paper studies and designs a two-wheel differential drive robot with strong passing performance,which can realize automatic inspection of instruments in petrochemical plants by carrying mechanical arms.The main work of this paper is as follows:Aiming at the problem that the driving wheel of traditional wheeled mobile robot is easy to slip or even hang in the air during obstacle crossing,a multi-suspension chassis structure was proposed to improve the robot’s passability.According to the working environment of the petrochemical inspection robot,the main parameters of the robot are defined,and the driving mode,driving system and frame structure of the chassis are determined through analysis and calculation.Solidworks is used to draw the overall three-dimensional model of the robot,and Ansys is used to conduct static analysis on the suspension mechanism and frame to ensure that its structural strength meets the requirements.Modal analysis is also conducted on the frame to prevent resonance from causing damage to the vehicle body.Establish obstacle surmounting and climbing models for multi suspension chassis and traditional chassis,and theoretically analyze the passing performance of the two types of chassis.The function of three basic modules of ADAMS software,the addition of chassis motion pair and the setting of related parameters are analyzed.Based on ADAMS,dynamic simulations were conducted for climbing the steps and climbing conditions of the two types of chassis,and the maximum obstacle clearance height of the multi suspension chassis was 8.4 mm,the maximum climbing angle was14 °,the maximum obstacle clearance height of the traditional chassis was 7 mm,the maximum climbing angle was 11 °,as well as the change curves of the displacement of the center of mass of the two types of chassis,the torque of the driving wheel,and the support force during the movement,to verify the correctness of the theoretical analysis.The key technologies of mobile robots and the ROS robot operating system are analyzed.Use Solidworks to establish the URDF model of the robot,and load it in Rviz to verify the correctness of the model.Based on the analysis,establish the coordinate system model,kinematics model,laser radar ranging model,and navigation function framework of the differential drive robot.The principle of particle filter algorithm was studied,and the simulation environment was built in ROS.Gmapping algorithm based on particle filter and Amcl algorithm were used for map construction and positioning simulation.Aiming at the problems of low searching efficiency and many inflection points of traditional A* algorithm,dynamic weight coefficient is introduced to improve the searching efficiency,and Bessel curve is used to improve the smoothness of the path.The principle of DWA algorithm is studied,and a grid environment is built in Matlab to simulate A* algorithm before and after improvement and DWA algorithm.The results show that the expanded nodes of the improved A * algorithm are reduced by19%,and the smoothness is effectively improved.Build an autonomous navigation framework in ROS,and conduct path planning and obstacle avoidance simulation for unknown obstacles using the fused A* algorithm before and after improvement and DWA algorithm.Build a prototype according to the design for real vehicle experiments.The maximum obstacle crossing height of the robot in the real environment is 9mm and the maximum climbing angle is 14 °,which is tested in the actual step and slope scenarios,verifying the passing performance of the robot.Test scenarios were built to test SLAM,path planning,and unknown obstacle avoidance,verifying the effectiveness of the algorithm. |
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