In this study, a novel enhanced anti-swing control method is proposed for underactuated overhead crane systems, which shows superior anti-swing control performance than most existing control methods. In particular, to increase the anti-swing control performance of overhead crane systems, an improved damping anti-swing signal is investigated based on a swing-related storage function. Subsequently, based on the anti-swing signal, a constructive Lyapunov function candidate is introduced and a new non-linear anti-swing control method is proposed straightforwardly, and the equilibrium point of the overall closed-loop system is proven to be asymptotically stable by Lyapunov techniques and LaSalle's invariance theorem. Some experimental results are provided to demonstrate the feasibility and effectiveness of the proposed control method. In addition, to illustrate the superior control performance of the proposed method, a comparison study between the designed control method and the existing control methods is provided as well.
IntroductionIn real-world applications, most of the existing systems are nonlinear systems. The control of non-linear systems has attracted a great deal of research interest in recent years. Owing to widely applications, many practical non-linear control methods have been reported in the literature [1][2][3][4][5][6][7][8][9][10][11][12][13]. As a typical underactuated nonlinear system one should recall the overhead crane, which is extensively utilised through out the world in thousands of shipping yards, nuclear power and waste storage facilities, and other industrial sites for material transportation. For underactuated overhead crane systems, the control objectives include transferring the load to the desired position quickly, stopping the trolley at the desired position precisely, and suppressing payload swing efficiently during the transportation. However, it is difficult to achieve the control objectives simultaneously because rapid movement of the trolley always accompanies the load swing. For this reason, it is usually challenging, if not completely impossible, to achieve these objectives at the same time. So far, to improve the effectiveness of underactuated overhead crane systems, many effective control approaches have been proposed in the literature. In particular, one representative openloop control approach is input shaping, which is applied in real time by convolving the desired step input reference signal with a series of chosen impulses to suppress the payload swing during the transportation process [14][15][16][17]. The key of input shaping technique is the requirement of priori known with respect to the system model knowledge. Therefore this technique is sensitive to system natural frequencies and damping ratios; moreover, variations of the suspended cable length during the transportation bring about some serious residual oscillations at the destination. Hence, to improve the robust performance of input shaping technique against the suspended rope length variations, many robust sha...