Unmanned Electric Shovel Based On Hybrid A-Star And SMC Trajectory Planning And Tracking Control Research

Electric shovels are the core equipment of the surface mining industry,often working in extremely hot,vibrating and dusty environments where safety and operational efficiency depend heavily on the experience of the operator.Statistics show that over 80% of accidents in the mining industry are caused by human error and over 30% are related to transport accidents.Therefore,with the advancement of mining intelligence,it is necessary to develop unmanned driving technology for electric shovels to improve the safety and efficiency of surface mining.This paper combines the Shanxi unveiling tender project " Research and Development of Unmanned Large Mining Shovel"(No20191101014)and the National Natural Science Foundation of China project " Intelligent Loading and Unloading Strategies and Multi-Objective Trajectory Planning for Unmanned Mining Electric Shovels"(No52105100)establishes the electromechanical coupling dynamics model of the electric shovel tracked chassis,and designs the driving characteristics of the electric shovel for the In this paper,a sliding-mode control-based trajectory tracking controller is designed and the control effect is verified by simulation and experiment respectively.Firstly,the significance of developing the intelligence of electric shovels and the current development status are systematically explained.The current research status in the fields of trajectory planning,trajectory tracking control and electromechanical coupling dynamics related to the autonomous travel function is summarised,and the research line and framework of this paper are established.Based on the kinematics and dynamics model of the electric shovel track chassis and the three-phase asynchronous motor model,the electromechanical coupling dynamics model of the electric shovel walking device is constructed,and the simulation verification of straight-line and curved driving is carried out.Translated with www.Deep L.com/Translator(free version)Considering the motion characteristics of the heavy-duty tracks of electric shovels,an improved hybrid A* algorithm is adopted to plan the walking path.The visual graph algorithm is used to overcome the slow search speed problem of the hybrid A* algorithm.Then,the conjugate gradient descent method and the cubic B-spline curve are used to smooth the planned path to improve its initial zigzag path.Finally,the dynamic window algorithm is used to solve the problem of multiple adjustments when reaching the target point.To verify the effectiveness of the proposed method,"Z" and complex maps are designed for simulation verification.The simulation results prove the rationality of the planning method proposed in this paper.A trajectory tracking controller based on sliding mode control is designed for the heavyduty crawler of the electric shovel according to its driving characteristics and walking characteristics.By establishing the motion equation of the crawler and designing the corresponding error variables,the sliding mode surface is designed and the appropriate approaching control law is selected for the sliding mode surface,and finally,the control laws for the speed and steering angular velocity of the electric shovel are solved.After the speed control law is designed,the kinematic model and electromechanical coupling dynamic model of the electric shovel are used for simulation verification.The results show that the proposed controller can meet the tracking requirements of the electric shovel while reducing the chattering near the sliding mode surface.To verify the practical application of the proposed methods,an electrically-driven dualtrack chassis was built based on RTK positioning equipment to simulate the electric shovel chassis.Tracking experiments on different trajectories were conducted to test the effectiveness of the proposed path planning method and sliding mode tracking controller.The working status of the motor during the tracking process was analyzed to prove the correctness of the electromechanical coupled dynamics model.In summary,this paper establishes the electromechanical coupling dynamics model of the electric shovel’s tracked chassis for the study of autonomous driving,and makes improvements to the conventional path planning algorithm so that it can meet the needs of electric shovel walking,and designs a sliding mode tracking controller to suit it,and verifies its rationality through simulation and testing.The theory and methodology presented in this paper have been tested in practice and can provide some reference for the development of unmanned driving of electric shovels.