| The generation of AGV has changed the traditional material transportation mode to a great extent.It has the advantages of less personnel participation,high transportation efficiency and adaptability to the future intelligent management of enterprises.The wheel drive systems,besides can have spin,arc turning function,such as can also realize about translation,oblique translation,and other functions,to achieve AGV omni-directional mobile.At present,the steering wheel has large rotary radius and small clearance from the ground,which is likely to take up large space of AGV car body and cause scratches with the ground,etc.Therefore,the development of a compact steering wheel is of great significance for promoting the improvement of automation degree of heavy-duty material transportation industry.Based on the actual operating conditions of enterprises,combined with the current development status of wheeled robot driving system,and the current research status of steering wheel technology.Through the analysis of the structure and performance of the main brands of the steering wheel in the market at present,the steering wheel drive system is determined to adopt the AC servo system to replace the cumbersome steering wheel positioning device through the steering wheel,making the overall steering wheel more compact.Using SolidWorks to complete the overall mechanical structure design of the steering wheel and the theoretical check of the transmission gear,using Hypermesh and ANSYS software to check the reduction box,the results show that the maximum stress is 137.607MPa,the maximum strain value is 0.175mm,the reduction box design meets the requirements of actual working conditions.At present,the AGV steering wheel has low clearance from the ground,which is prone to the problems of steering motor and scraping with the ground.With the advantages of high precision and good speed of the servo system,the AGV compact servo steering wheel was developed,and the parameters were compared by combining with the steering wheel of the main brands.The results show that the clearance of the steering wheel from the ground can reach 70mm,the overall height 300mm and the turning radius 225mm,which are better than the structural parameters of the similar type of steering wheel.Dual-wheel AG Vs have the problem that the steering wheel movement does not coordinate,resulting in operation interference and unable to give full play to the steering wheel drive performance.Based on the theory of rigid body plane motion and the AGV of the steering wheel arranged diagonally,the kinematics modeling is carried out as a general double steering wheel application form,and the simulation of path tracking is carried out by using ADAMS.The results show that the driving torque of the steering wheel does not exceed the peak torque of the servo system,and the maximum deviation between the simulation track and the theoretical track is 8.36mm.Within the deviation range required by working conditions,the steering wheel design meets the requirements of working conditions.Based on the AGV with rated load of 3T as the experimental platform,the experimental system of the steering wheel was built to complete the performance test experiments such as load startup,path tracking and horizontal traverse of the steering wheel prototype.The speed response and current data of the steering wheel in the experiment were collected and analyzed.The results showed that the current data in the no-load performance test of the steering wheel was stable at about 2.5a.In the test of the bearing performance of the steering wheel,the peak current at startup is about 68A,and the maintenance time is about 0.3s,and the current floating at subsequent stable operation is about 10A.In the transverse shift test,the driving current of the steering system is stable at about 6.5A.The path tracking experiment and obstacle avoidance experiment were carried out on the steering wheel AGV.The speed in the operation process could respond quickly with little motion interference,the current could be stabilized quickly and less than the rated current,and the driving ability of the steering wheel could meet the requirements of the working condition. |
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