Research On Positioningandanti-sway Controloftower Crane’s Multi-input Multi-output System Under Wind Load

Tower cranes are widely used in various engineering projects and have a huge market space.During tower crane construction,the hoisting weight will swing,which affects efficiency and has potential safety hazards;control tower crane rotation,luffing,and hoisting mechanisms to move separately in sequence,simple control,but low efficiency;wind load will aggravate hoisting swings,or even lose control,Must stop work,delay the construction period.At present,there are more researches on the positioning and anti-sway control of the tower crane with only luffing motion and reversing amplitude compound motion,and the wind load is not considered.This paper studies the positioning and anti-sway control of the tower crane’s strong coupling nonlinear system from the perspective of wind load and the coordinated movement of the rotation,luffing and hoisting mechanisms,so as to improve the construction efficiency of the tower crane.Specifically,the main research content of this thesis has the following parts:(1)Dynamic modeling and simulation of tower cranes with wind load.Taking the laboratory tower crane as an example,the Lagrangian method is used to establish the nonlinear dynamic model of the tower crane rotation,luffing,and lifting under wind load.It not only modifies the corresponding dynamic equations of lifting generalized coordinates in the existing literature,but also adds wind load to the generalized coordinates of hoisting swing angle and deflection angle.Then the dynamic model is solved and converted into an acceleration model,and a simulation model is built to verify the correctness of the tower crane dynamic model after modification and the necessity of adding wind load.(2)Stability analysis of tower crane’s nonlinear dynamic system.The nonlinear dynamics model of the laboratory tower crane is further transformed into a state space equation to solve the equilibrium state of the tower crane system.Lyapunov’s first method(indirect method)and Lyapunov’s second method(indirect method)are used to analyze and prove that the nonlinear system of the tower crane is stable.The input-output stability theorem is applied to analyze and prove that the nonlinear system of the tower crane is input-output stable.(3)Design of positioning and anti-sway controller for tower crane multi-input multi-output system under wind load.The partial feedback method is adopted to linearize the system,and the linear feedback positioning control law is designed.The linear approximation method is used to analyze the remaining internal zero dynamics,and the linear feedback anti-sway control law is designed.Considering the stable static wind load,the feedforward control law is designed to compensate.The tower crane is based on the feedforward partial feedback positioning and anti-sway control system,the positioning and anti-swaying efficiency is low,and the control performance of the control system becomes worse as the desired signal changes.Combining the sliding mode variable structure method to analyze the internal zero dynamics and improve the anti-sway control law.Although the control system limits the swing angle and peak deflection angle of the load to about 1°,the positioning and anti-sway efficiency is greatly reduced,and the control system is not resolved.The problem of poor adaptability to expected signal changes.Combined with the accurate feedback method to analyze the internal zero dynamics and improve the anti-sway control law,the control system improves the positioning and anti-sway efficiency by 33% or even higher,but it does not solve the problem of the control system’s deteriorating control performance as the desired signal changes.(4)Optimization of positioning and anti-sway controller for tower crane multi-input multi-output system under wind load.Combining genetic algorithm,setting multi-objective function,optimizing parameters for discrete points in the expected signal interval,and generalizing the optimization result to the entire expected signal interval by linear interpolation to obtain the functional relationship between the expected signal and the optimized parameters.This combination of genetic algorithm,Precise feedback method based on wind load feedforward partial feedback positioning anti-sway control system,which can make the tower crane work efficiently when there is wind load,and has very strong adaptability to the hoisting quality and expected signal changes.Very high application value.