Research On Multi-coupling Behaviour And Trajectory Control Technology Of Electric Shovel Autonomous Walking

Mining is an important part of the national economy,and open-pit mining accounts for a large proportion of the entire mining industry.The large-scale electric shovel is the main mining equipment for stripping and digging ore in open-pit mines.The poor working environment and long work hours of operators make the accident rate of electric shovels relatively high.Among them,the accidents related to walking devices account for about 1/3,it can be seen that the walking device has an important influence on the reliability of the driving performance of a large-scale electric shovel.With the continuous improvement of the intelligent level of mineral equipment,the unmanned electric shovel has become a new solution.Here,autonomous walking is a key function of the unmanned electric shovel,multicoupling behaviour exists in the process of autonomous walking,which mainly includes electromechanical coupling,coupling of discrete medium system and multi-body dynamics system,and coupling of trajectory tracking control and electromechanical characteristics.However,the level of intelligence of large-scale electric shovels in our country is backward,and most of the core technologies are still monopolized by foreign countries.Therefore,improving the intelligence level of large-scale electric shovel walking device is of great significance to the research and development of my country’s large-scale electric shovel.First,the kinematics and dynamics characteristics are analysed based on the typical operating conditions of the electric shovel,combining with the asynchronous motor dynamic model,the electromechanical coupling dynamics model under the typical operating conditions of the electric shovel is established.The corresponding electromechanical characteristics under typical working conditions are analysed through the MATLAB/Simulink,the variation of the current,voltage,load torque of the asynchronous motor and the crawler running velocity is obtained,and the regenerative braking steering occurs when the electric shovel is turning.Meanwhile,to obtain the coupling behaviour of the track and the sand-gravel pavement,the coupling method of discrete element method and multi-body dynamics is used to explore the influence of the pre-tension force,the road-wheel spacing,the sprocket speed,and the grouser height on the ground pressure distribution,power,tractive force,and track tension,the significance of the influencing factors and interactions on the driving performance of the tracked chassis is further analysed.On this basis,the crawler chassis driving performance prediction model is established based on the Kriging method,and the interactive response of the crawler chassis driving performance is analysed through the response surface analysis method.Finally,the performance of the tracked chassis is optimized based on the genetic algorithm,and the optimization results and optimization effects are analysed and verified.Furthermore,combining the operating characteristics and structural characteristics of the electric shovel,an A-RRT* path planning method suitable for electric shovel walking is proposed,and its path planning effect is analysed.The results show that this method can effectively eliminate the sharp turning phenomenon in the planned path;Secondly,an inversion sliding mode trajectory tracking method based on Lyapunov is designed.And to consider the influence of electromechanical coupling characteristics,sag,and slip on the trajectory tracking performance,the trajectory tracking performance of the electric shovel is analysed and preliminarily verified by the fusion method of the dynamic model of the asynchronous motor and the virtual prototype of the electric shovel.At the same time,the slip rate of the crawlers on both sides is studied,and it is found that when the crawler running velocity is high,the skid phenomenon is obvious,and the slip phenomenon is more obvious with a low crawler speed.Furthermore,the electromechanical parameters of the track on the inner side of the steering show obvious fluctuation characteristics.On this basis,the established trajectory tracking method and path planning method are integrated to track different planned trajectories.The results show that the electric shovel can effectively track the trajectory,and there are no sharp turns and frequent turns during the tracking process.Finally,an electric shovel trajectory tracking system is constructed based on Real-Time Kinematic positioning technology,and the corresponding trajectory tracking experiments are carried out on different driving trajectories to verify the actual application effect of the established inversion sliding mode trajectory tracking method and trajectory tracking system,and the corresponding variation of electromechanical parameters and the working status of the crawler asynchronous motors on both sides during different trajectory tracking processes is analysed.It is found that the regenerative braking steering phenomenon occurs when the electric shovel is turning,the load and the power consumption of the outer asynchronous motor are relatively large,and the inner asynchronous motor appears in the generator working state,which is consistent with the theoretical analysis result.In summary,the electromechanical coupling dynamics model for the electric shovel is established.The coupling behaviour between the track and the ground during the travelling of the electric shovel is analysed.A path planning algorithm and a trajectory tracking method suitable for large-scale electric shovel are constructed,their effectiveness is verified and the corresponding electromechanical performance is analysed through numerical simulation and experiments.The research work of this paper can provide a reference for the improvement of the intelligent level of driving performance of large-scale electric shovel in my country.