| Because of its advantages of high efficiency,rapidity and cleanliness,palletizing robot has been widely used in the production line of industrial manufacturing.It is an important equipment to achieve the automation of modern manufacturing industry.For the production line of aluminium ingot continuous casting,the reliability and stability of the palletizing robot have a great impact on the production efficiency and economic benefits of the whole production line.The vibration of the manipulator,as the key component of the palletizing robot,will seriously affect the stable operation of the whole machine,and even cause the fracture of the manipulator.Therefore,the analysis of the dynamic characteristics of the palletizing robot under high speed and heavy load is helpful for the optimization of the palletizing robot structure and the design of the controller.And it has a great significance to enhance its stability and working speed.The main research contents and results are as follows:(1)The overall structure and the position relationship of the high-speed and heavy-load palletizing robot are studied.Wittenburg's graph theory analysis method is used to analyze the structure and force transformation of the multi-links palletizing robot.The relationship between the motion and the force(force moment)of each joint is obtained by the tree diagram of the palletizing robot.Then,the D-H parameter method is used to establish the position relationship of each joint of the palletizing robot.The pose of the terminal point in the base coordinate are obtained by the operation of the homogeneous transformation matrix.The results show that the motion of the terminal point meets the requirements of the workspace.(2)The dynamic characteristics of the palletizing robot under high speed and heavy load is studied.According to the high-speed and heavy-load working conditions of MPL300 palletizing robot,the basic dynamic parameters graph of the palletizing robot are given.The dynamic model of the palletizing robot with flexible joints under load is established using Hamilton's principle.Afterwards,its mass matrix,stiffness matrix and Coriolis acceleration matrix are deduced.The motion equation is solved by the fifth order Runge-Kutta method,and the motion parameters(displacement,velocity and acceleration)in a working period are obtained,and the results show that the influence of inertia force on joint which caused by joint flexibility can not be neglected,and the vibration mainly concentrates on the joint of the small arm,and even causes the joint of the small arm to bear a certain cyclic load(inertia force).(3)The joint vibration characteristics of the palletizing robot under high speed and heavy load are studied.Aiming at the joint vibration of the palletizing robot under high speedand heavy load,the frequency response and time-frequency characteristics of each joint vibration are obtained by Fourier transform based on the displacement parameters of joint deformation.The joint vibration characteristics of the key parts of the palletizing robot are analyzed.The results show that the vibration occurs at the moment of started,stopped and the direction of motion changed.(4)The dynamic characteristics of the palletizing robot are simulated.According to the real working conditions of palletizing robot,the simulation environment is determined and the virtual prototype of the palletizing robot is established by ADAMS.The driving function of palletizing robot is obtained by ADAMS.The dynamic response characteristics of the palletizing robot are simulated to verify the rationality of the design of the palletizing robot.(5)The dynamic characteristics of key parts of palletizing robot are studied.Based on the acceleration parameters of the small arm joints of the palletizing robot,the dynamic stresses of each section of the arm are calculated,and the fracture causes of the arm are analyzed.The results show that the alternating cycling of tension and compression stresses is the main factor for the fracture of the arm. |
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