Research On Anti-swing Placement Method Of Tower Crane Based On Nonlinear Coupling Control

Tower crane is a kind of nonlinear electromechanical equipment with complex underactuated characteristics,which is widely used in modern construction sites.Its dynamic model is highly nonlinear in nature and belongs to the underactuated type.In addition,the drive is far away from the payload,making the mechanism movement within the system out of synchronization.This results in large load oscillations,poor positioning accuracy,poor interference immunity and even increased safety hazards.For decades how to design a suitable controller to reduce the swing of the payload to improve the efficiency of tower crane,accurate positioning and safe production has been an important research topic for scholars at home and abroad.Traditional manual and automatic control methods are difficult to be controlled effectively,so it is necessary to design a suitable controller to achieve the above purpose.In this paper,aiming at the anti-sway placement control of underactuated tower crane during the operation process,the main research contents are as follows:(1)According to the theoretical premise required by the energy coupling method,after in-depth analysis of the problems that need to be solved urgently in the nonlinear system control of the underactuated tower crane,the basic theories of several commonly used underactuated tower cranes and the structural principles of the experimental platform are proposed.It mainly includes the D’Alembert principle and Euler-Lagrange equation in dynamic modeling,the Lagrangian method and La Salle invariance principle when designing controllers and verifying system stability.And the theoretical basis is linked to the underdriven coupled anti-swing control of tower cranes to provide the theoretical basis for the work done in the following work.(2)In response to the tower crane trajectory planning methods in terms of the unsteadiness of the load transporting process and the shock caused to the system by the control drive,this paper firstly uses D’Alembert’s principle equation to establish the dynamics model of a single pendulum type tower crane.Then after analyzing the process of the tower crane lifting the load,a non-impact sine acceleration S-shaped trajectory motion curve is designed,and it was compared with the widely used three-stage acceleration transportation trajectory planning method.The proposed trajectory planning method can achieve the anti-sway performance of the load while reducing the impact of the control driving force on the system.(3)This paper designs a control law based on energy coupling to achieve the purpose of load sway resistance for tower cranes transporting loads in three-dimensional space,compared to most existing two-dimensional planes where the analysis of load sway is not comprehensive.The Lagrange equation is used to establish a three-dimensional spatial tower crane dynamics model,and the controller is designed by using the energy coupling method in the context of the dynamics model,meanwhile the coupling between load sway and control input is enhanced by improving the energy function of the system.(4)Comprehensive consideration is given to the problem of secondary pendulum motion where the load may swing relative to the hook during actual operation,which is more complex to deal with at this point.This makes the effective suppression of the pendulum angle and the immunity of the system even worse.To address these problems,an improved design method of strong energy coupling is proposed to enhance the coupling relationship between multiple variables.The dynamic model of the secondary swing of the tower crane transporting load process is established by using Lagrange’s equation,and an error signal containing two levels of swing angle and system state information is designed.A Lyapunov scalar function is designed by improving the mechanical energy function of the system,and the stability analysis is also carried out by using La Salle’s invariance principle.The above designed control method is verified by simulation analysis through MATLAB/SIMULINK and the tower crane experimental platform.The results show that the control method studied in this paper achieves a strong coupling relationship between the state quantities of the tower crane transporting load process and reduces the impact of the control drive.Specifically,the proposed control scheme can achieve precise positioning of the rotational and translational motion process of the tower crane,effective swing angle suppression and excellent control robustness.This is of great significance for solving the tower crane load swing resistance problem and has good market application prospects.