Optimization Design Methods Of The Excavating Trajectory For Intelligent Electric Shovels

An Electric Shovel(ES)is one kind of large mechanical excavators and usually used in the open-pit mining to excavate the blasted material.As a core equipment in the open pit mine,the ES reflects the level of one country in the equipment manufacturing industry.Due to the huge and complex structure,the various material pile surfaces,etc.,the excavating trajectory planning for the ES becomes an intractable problem.Thereby,the traditional manual operation can hardly realize the excavation tracking to the optimal trajectory,which may lead to low efficiency,insta-bility,and high energy consumption for the ES.To address all the problems mentioned above,the intellectualization of the ES can be a good solution.In this dissertation,the WK-55 ES is selected as the research object,based on which the excavating-trajectory-related problems are studied.A dynamic excavating resistance model taking into account ES’s working character-istics is established.A collaborative design strategy synchronously dealing with ES’s structure and trajectory for the typical pile surface is proposed.To realize the automatic excavation for complex pile surfaces,a rapid online excavating trajectory planning method is established.The main research contents are as follows:1)The working characteristics of the ES is first studied.By using a dynamic modeling method for the cumulative volume of the loaded material in the dipper,the dynamic excavat-ing resistance model is established for ES’s excavating process.This dynamic model takes into account not only the loaded material gravity,the friction between the dipper walls and the ma-terial,etc.,but also the influence from the excavating speed on the material properties and the inertia force.An excavating test is also conducted and relevant results certify that the established dynamic excavating resistance can improve the accuracy by at least 14%compared with the con-ventional excavating resistance models.Then,a global sensitivity analysis is performed for the newly established excavating resistance model on relevant parameters.2)A three-dimensional finite element model of ES’s front working mechanism is estab-lished by using the analytical method.By this model,the statics and dynamics computations only take 0.75s and 4.4s,respectively.The stress distribution and the vibration obtained from the above computations can match the results of relevant references.Then,it can be concluded that the established finite element model has enough computational efficiency and accuracy,and it can lay a solid foundation for the consideration of the vibration and structure safety during the excavating trajectory design.3)To meet the requirement of the typical excavating trajectory during ES’s automatic oper-ation and deal with the interaction between ES’s structure and trajectory,a collaborative design method(Codesign)simultaneously processing both of the structure and trajectory parameters is proposed.To realize this asynchronous processing,a RBF surrogate based trajectory planning(RBF-TP)method is proposed,which transforms a timing problem to an optimization problem of a space point set.Then,based on the RBF-TP,the universal model of the Codesign for the ES is established.By comparing with the traditional sequential optimization method,the Codesign can decrease the energy consumed by per volume of the loaded material by 7.85%.A test is also conducted to verify the superiority of the Codesign method.4)To realize the automatic excavation of the intelligent ES for the complex pile surfaces,an online rapid trajectory planning(RTP)method for ES’s excavating trajectory is proposed based on the discretization ideas.By performing a case study for this online RTP method,it only takes 6.63s to complete the excavating trajectory planning,which meets the requirements of the rapidity,the high fillability and the low-energy consumption for the ES’s intelligentization.Then,numerical tests are performed for the online RTP method by dealing with the material pile with different pile angles and complex surface types.Results show that all the computing time is less than 1 Os,which reflects the computational efficiency and the high applicability of the online RTP method.