Research On Loader Drag Reduction Strategy Based On Electro-hydraulic Proportional Control

In the "14th Five-Year" plan,the development of social science and technology has been further promoted.As the main force of engineering machinery in today’s society,loaders’ adaptability and energy saving have gradually become the focus of research.However,in the more common loaders nowadays,the operating system is quite complicated and the driver is required to have high operating skills during the shoveling process.Due to the impact of material resistance,it will aggravate tire wear and cause waste of power in the process of shoveling,but most of researches achieve the purpose of drag reduction through complex control systems or adding multiple components to the working mechanism.Therefore,it is necessary to realize the energy-saving characteristics of the loader without increasing the existing structure.This paper takes the school-enterprise cooperation project "Loader Development"(project number: FW/RD 201640)as the research object.After analyzing and comparing a large number of domestic and foreign literatures,the article introduces the development status of loaders and summarizes the current research status of the loading electro-hydraulic proportional control system and its intelligent drag reduction control strategy.Through research,it is found that for the current loader,its bucket shape has tend to be complete,and there is less room for continued lifting.Therefore,it is necessary to change its motion trajectory to achieve the purpose of energy saving.This article analyzes the resistance changes and force conditions of the loader during operation and studies the physical characteristics of the material in the shoveling process and the formation mechanism of the compaction core and slip surface.Based on the DH coordinates,the trajectory equation of the bucket was established.A control strategy was proposed to reduce the insertion resistance by changing the motion posture of the boom when the traction force could not overcome the ground resistance.Subsequently,the accuracy of the strategy is verified through the simulation on the shoveling process of different materials by EDEM.The proposed control strategy is analyzed in detail: the resistance of the material will increase with the bucket inserting into the pile;when the maximum traction force of the loader is exceeded,the speed of the loader will rise sharply;at this time,the sensor used to detect the tire speed will output a difference signal,which is transmitted to the boom side of the hydraulic system of the working device through the controller,and the boom is driven to destroy the dense verification in the pile;finally the purpose of balancing power is achieved.The proposed control strategy is analyzed in detail and the design of the electro-hydraulic proportional control system is completed,which is also explained in detail.What’s more,the relationship between the control current of the speed sensor and the force on the piston rod of the driving cylinder is obtained through the calculation of the transfer function.The loader working device platform was built using AMESim software,which verified the feasibility of the function by applying a certain step signal to the pressure reducing valve to simulate the actual drag reduction process.An experiment plan for drag reduction insertion was designed,during which the effective performance of the drag reduction insertion was proved through the measurement of the pilot pressure at the pressure reducing valve,which provided a certain reference for the control research of the drag reduction insertion in the future.