Time Optimal Simulation Analysis Of Typical Working Conditions Of Three Arm Backhoe Hydraulic Excavator

The boom of three arm backhoe hydraulic excavator is composed of upper and lower sections and connecting oil cylinder to form a combined boom.This model can adjust the included angle between the two booms and the excavation direction of the bucket according to the working conditions.Compared with ordinary backhoe hydraulic excavator,it has the advantages of flexible operation and large excavation range.This model appeared earlier abroad,but it is rare in China,and there is little research on it.Taking this model as the research object,this paper studies the kinematics and dynamics of its working device and the time optimal control of typical working conditions.The specific contents are as follows:The D-H method is used to establish the vector equation of the change between the bucket tooth tip position and the relative position(rotation angle)of the main components,deduce the forward solution and inverse solution of the kinematic position and the functional relationship between the oil cylinder and the rotation angle,simulate the functional relationship between the oil cylinder length and the relative rotation angle,and preliminarily verify the correctness of the model.The corresponding analysis program is compiled in MATLAB to generate the excavation envelope diagram of the model,analyze the size and corresponding change law of the main operation parameters at the limit position of the connecting oil cylinder,and fit the mathematical relationship between the main operation parameters and the length of the connecting oil cylinder.Taking the variation range of each corner as the constraint condition,the operation range of 30° slope repair,leveling and foundation pit excavation is analyzed,and compared with the operation range of the same type of ordinary hydraulic excavator.The results show that the three arm hydraulic excavator has stronger adaptability under typical working conditions.The path points passing through the 30° slope repair condition are determined through the inverse solution.According to the kinematic constraints,the 4-3-3-3-4 piecewise polynomial is used for interpolation,and the PSO algorithm is used to optimize the interpolation time of each joint,so as to obtain the optimal interpolation time under the constraints,and then the position,velocity and acceleration curves of each joint are obtained.Considering that the drive of the excavator comes from the hydraulic cylinder,the obtained joint change curve is transformed into the change of the corresponding hydraulic cylinder,which provides a basis for the excavation trajectory control under specific working conditions.The Lagrange dynamic equation of the working device is established.The dynamic simulation of three typical working conditions of 30° slope repair,leveling and foundation pit excavation is carried out in ADAMS,and the force change curves of the hinge points of the upper and lower boom,bucket rod and bucket are obtained,which provides a reference basis for structural design.