Research On Swing Control Of The Grab Ship Unloader Considering The Elasticity Of Wire Rope

Grab ship unloader is a kind of bulk cargo loading and unloading equipment which is widely used in port and dock along the sea and river.Whether the swing control of grab is effective,directly affects the actual working efficiency of ship unloader.The existing researches generally control the swing of the grab by establishing the dynamic model of the trolley-grab system and applying the input shaping method,while the hoisting wire rope usually is considered as a rigid rope in the dynamic model,ignoring the effect of elasticity.Since the accuracy of dynamic model will directly affect the effectiveness of swing control,it is necessary to establish a more accurate dynamic model to study the swing control of grab ship unloader.In this thesis,a trolley-grab system dynamic model considering the wire rope elasticity is established to study the swing control of grab,and a simulation verification is carried out based on virtual prototype technology.The main work done is as follows:(1)Considering the elasticity of wire rope,the dynamic model of trolley-grab system is established based on Lagrange equation,and compared with the existing pendulum model that does not take into account the elasticity of wire rope.In addition,the system natural frequency and damping ratio are obtained by simplifying the model.(2)The grab running path is planned by considering the working efficiency and the change of swing rope length of ship unloader,and then the swing control simulation model of trolley-grab system based on elasticity wire rope model is established by using MATLAB/Simulink.Furthermore,the classical swing control methods are simulated and analyzed in MATLAB/Simulink,and the results show that the elasticity of the rope has a certain impact on the swing angle control in case of higher control accuracy requirement.(3)An improved NZV swing control method is proposed,and the simulation results show that for the model of considering the elasticity of the wire rope the improved NZV method has a better swing control effect than the typical swing control methods,which not only can meet the grab swing angle control but also can improve the work efficiency of ship unloader.The sensitivity analysis of grab swing angle under the elasticity parameters shows that the maximum residual swing angle of grab is more sensitive to the change of wire rope diameter than the elastic modulus.(4)A virtual prototype model of grab ship unloader is established based on virtual prototype technology,in which flexible wire rope and pulley group system are created by using ADAMS/Machinery Cable module,realizing the parametric modeling of wire rope.Moreover the correctness of the theoretical mathematical model is verified by simulation.In addition,the effect of grab swing control is simulated and analyzed,which shows that the change of center of gravity caused by grab opening/closing operation should be considered in the grab swing control.