| In response to the call of the State Council's Guidance on Promoting the Construction of Urban Underground Comprehensive Pipe Gallery,underground comprehensive pipe galleries have been vigorously built in many metropolis.Due to the compact interior space and massive cross-sections in the pipe galleries,the operation and maintenance problems have become increasingly prominent.Typically,the underground comprehensive pipe galleries are monitored by a combination of fixed monitoring equipment and manual inspections.However,the problems are that poor maneuverability of fixed monitoring equipment,low labor productivity and high-risk inspections cannot meet the actual needs of comprehensive pipe galleries in smart cities.Therefore,according to the features of underground comprehensive pipe gallery,an omnidirectional system of patrol vehicles is researched in this thesis,which is significant to monitor comprehensive pipe gallery without blind area.Firstly,the structural characteristics of current omnidirectional patrol vehicles are summarized in this thesis,and a new omnidirectional steering system based on in-wheel motors is proposed,including steering transmission mechanism,steering switching devices,in-wheel motors and related control section.In this system,one steering motor drives four in-wheel motors to rotate.The steering system can realize four-wheel steering,omnidirectional steering and lateral movement.The transmission parameters of main parts are determined by driving requirements and mechanical structure analysis.Secondly,kinematics and dynamics analysis of the omnidirectional vehicle is carried out,and the models and parameters of two kinds of motors are determined.According to the steering motion modes and structural characteristics,the speed and torque distribution principles of the patrol vehicle in two steering modes are deduced.Based on the Adams simulation platform,the motion relationships between the angle output of the steering motor and the wheel deflection are analyzed.Design parameters of steering motor are obtained from simulation data.The design parameters of in-wheel motors are calculated according to the force characteristics of patrol vehicle.Then,the control strategy of the omnidirectional steering system is established based on its kinematics analysis.The control rules of two steering modes are designed according to the control requirement and the speed regulation characteristics of hub motor.Then an adaptive double closed-loop fuzzy PI control scheme is selected.Finally,simulation analysis is carried out on virtual models and a semi-physical model.The four-wheel in-wheel motor differential steering model based on adaptive fuzzy control system is established by Simulink simulation platform.The rotational speed response curves and four-wheel linkage response curves are obtained.And the actual control response results of the rear wheels are obtained through the semi-physical simulation. |
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