Grab Ship Unloader Trolley- Grab System Dynamics Modeling And Swing Control Research

The grab swing control effect of grab ship unloader is an important indicator which affects its work efficiency, while input shaping method is usually used to control swing of the grab ship unloader, and an accurate dynamics model of the trolley-grab system needs to be established in this method. However, the traditional modeling methods generally regard the grab as a mass point and neglect the change of the center of grab bucket gravity when the grab is opened and closed. In this thesis, a double pendulum dynamic model of trolley-grab system is established to study its dynamic characteristic and swing control when the grab is opened and closed. The main work and innovations are as follows :(1)The shape of grab and the change of rope length is to be considered, and a double pendulum dynamic model of trolley-grab system is established by using Lagrange equation, furthermore the double pendulum mathematics model is resolved by using the fourth-order Runge-Kutta method, then the second order iteration relationship between the swing angel and angular acceleration is obtained.(2)A three-dimensional dynamics model of the trolley-grab system is established by using ADAMS software in the thesis, and on the trolley-grab movement plane where its second order oscillation frequency is analyzed, besides the correctness of the theoretical model built in this thesis is verified; meanwhile, under the grab is opened and closed condition, the center of gravity changes is to be analyzed, the result has shown that the grab at different state(opened, closed), the change of the center of gravity has effect on its gravity.(3)An improved ZV anti-sway control method is proposed, the work efficiency and safety is considered, then the grab ship unloader planning moving path can be obtained, besides the simulation case has shown that the improved ZV control method has a good effect on swing control; By comparing the simple pendulum with the double pendulum control model in the same control parameters, found that the first-order of the double pendulum's swing is agreed with the motion of the simple pendulum.(4)The trolley-grab double pendulum swing control system simulation software is developed based on VB 6.0, and by the simulation software, not only can obtained the trolley and hoisting planning speed curve, the center of grab gravity trajectory and the second order of swing angle changing curve, but also can real-time simulation analyzed the proposed improved ZV method control effect.