Trolley Dynamics Research Articles

해양크레인시스템의 수정된 2차 슬라이딩모드제어

In this paper, a super-twisting (i.e., modified 2nd-order) sliding mode control (STSMC) is proposed for sway control of an offshore container crane system (i.e., a mobile harbor system equipped with a container crane on it). The mobile harbor is used for ship-to-ship transfer of containers, where the container ship is anchored in an open sea. To load/unload the containers in an open sea, it is necessary to suppress the position error of the load caused by the wave-induced movements of the mobile harbor. In this paper, a super-twisting sliding mode controller is developed for suppressing the position error of the payload. The sliding surface is designed in such a way that the longitudinal sway of the load is incorporated within the trolley dynamics. The chattering problem is also solved by utilizing a second order sliding surface. Lyapunov function-based stability analysis is performed to prove the uniform stability of the closed-loop system. Simulation results are provided to prove the effectiveness of the proposed control law.

Fuzzy sliding mode control of container cranes

A fuzzy sliding mode control strategy for container cranes is discussed in this paper. In which, the sway motion of a payload is integrated into the trolley dynamics in a sliding surface. This scheme guarantees the asymptotic stability of the closed-loop system. Moreover, the control gain, which is the most important component, is a flexible gain and is tuned based on fuzzy laws to avoid chattering phenomena of the system. The performance of the closed-loop system has been simulated using MATLAB. In addition, to illustrate the efficiency of the proposed control law, experimental results are also provided.

Sliding-Mode Antisway Control of an Offshore Container Crane

In this paper, a sliding-mode control for an offshore container crane is discussed. The offshore container crane is used to load/unload containers between a huge container ship (called the “mother ship”) and a smaller ship (called the “mobile harbor”), on which the crane is installed. The purpose of the mobile harbor is to load/unload containers in the open sea and transport them to shallower water where they can be offloaded at existing conventional ports, thereby obviating the need for expansive and expensive new facilities. The load/unload control objective is to suppress the pendulum motion (i.e., “sway”) of the load in the presence of the wave- and wind-induced movements (heave, roll, and pitch) of the mobile harbor. A new mechanism for lateral sway control, therefore, is proposed as well. A sliding surface is designed in such a way that the longitudinal sway of the load is incorporated with the trolley dynamics. The asymptotic stability of the closed-loop system is guaranteed by a control law derived for the purpose. The proposed new mechanism can suppress lateral sway, which functionality is not possible with conventional cranes. Simulation results are provided.

Adaptive sliding mode control of container cranes

An adaptive sliding mode control scheme for container cranes is investigated in this study. A sliding surface is designed in such a way that the sway motion of the payload is incorporated into the trolley dynamics. Included in the proposed control law is a varying control gain, obtained by an adaptation law, which transitions the system into the sliding mode. The control law guarantees the asymptotic stability of the closed-loop system. To demonstrate the efficiency of the proposed algorithm, experimental results are provided.

Modelling and control of the motion of a trolley: Effect of motor dynamics on the dynamical model

This work deals with the modelling and control of the motion of a trolley. The trolley is composed from two rear wheels, each of them controlled separately by a DC-motor, and from a front castor wheel (see Figure 1). In order to obtain a set of dynamic equations of the trolley motion that include the motor dynamics, the trolley dynamics and the motor dynamics are coupled to obtain a set of third-order differential equations. Then two inverse dynamics transformations are applied successively, to enable one to use linear control for the design of guidance laws for steering the trolley.

Position and swing angle control for loads of overhead cranes

This paper presents a systematic design method of an anti-swing control law for overhead cranes. A velocity servo system for the trolley of a crane is designed based on the dynamics of the trolley and its load. The velocity servo system compensates for the effects of load swing on the trolley dynamics so that the velocity servo is independent of load swing. The velocity servo system is used for the design of a position servo system for the trolley via the loop shaping method. The position servo system and the swing dynamics of the load are then used to design an angle control system for load swing based on the root locus method. The combined position servo and the angle control systems constitute the overall control system. In the presence of low frequency disturbances, the proposed control law guarantees accurate position control for the trolley and fast damping for load swing. Furthermore, the performance of the proposed control law is independent of the mass of the load. Experimental results on a prototype crane show the effectiveness of the proposed anti-swing control law.