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Skew control of a quay container crane
Quang Hieu Ngo,홍금식 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.12
In this paper, the skew control of the load (container) in the quay crane used in the dockside of a container terminal is investigated. The mathematical model of the 3-dimensional (3D) motions of the load is first derived. The container hooked to a spreader is suspended by four ropes in air. When the container is accelerated by the trolley or is disturbed by winds, it will make a rotational motion (trim, list, and skew) as well as a sway motion in the vertical plane. In such a case, the position of the container becomes difficult to control accurately due to the rotational motion even with the sway motion under control. This paper proposes an input shaping technique for the skew control based on the 3D dynamics of the container. The adopted skew control system uses four electric motors to vary the length of the four ropes individually. Simulation results show the effectiveness of the proposed system in controlling the skew motion.
Command Shaping for Vibration Reduction of Container Cranes
Quang Hieu Ngo,Yanghai Nan,Keum-Shik Hong 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10
A combination of command shaping and bang/off-bang control scheme for container cranes is investigated in this paper. A linear model of the system is used to design the input shaper, where the trolley acceleration is given as an input, for suppressing the payload vibration. Bang/off-bang control guarantees that the trolley reaches the goal position By utilizing an industrial servo motor and its driver, the acceleration command from input shaper is integrated to become the velocity command for the motor. The control algorithm is simulated with the nonlinear system. The robustness of the control system is also evaluated with the natural frequency has ± 10% uncertainty (rope length variation).
Orientation Control of a Crane’s Spreader
Quang Hieu Ngo,Yonggyun Yu,Eun Ho Kim,In Gwun Jang,Keum-Shik Hong 제어로봇시스템학회 2011 제어로봇시스템학회 국제학술대회 논문집 Vol.2011 No.10
In this paper, the orientation control (trim, list, and skew control) of the load (container) in the crane located in the mobile harbor (MH) is investigated based on the derived mathematical model of the four-rope crane. A container hooked to a spreader is suspended in air by four ropes. When the container is accelerated by the trolley or is disturbed by winds, it rotates (trim, list, and skew) as well as sways in the vertical plane. When this happens, the accurate positioning of the container becomes difficult because of the rotation even with the swaying under control. This paper proposes a feedback control technique for the orientation control of the container based on the dynamics of the spreader including the container. The adopted control system uses four actuators that vary the lengths of the four ropes, respectively. Experiments are performed with a 1/20 scale MH, in which four snag devices are used, instead of the ball screws as a conventional crane in practice, to vary the rope lengths.
Active Control of an Offshore Container Crane
Ngo Phong Nguyen,Quang Hieu Ngo,Quang Phuc Ha 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10
Open sea loading/unloading cargos provides a potential solution to tack the problem related with port construction, expansion and congestion. This process involves a crane attached to a mobile harbor (MH) which can dynamically handle container from a large container anchored in deep water. The control objective during the operation is to maintain the payload in the desired position in the presence of ocean waves. This paper presents a robust control strategy for trajectory tracking and sway suppression of an offshore container crane. A fuzzy sliding mode control law is proposed for that. Experimental results are provided to indicate the efficiency of the proposed control strategy.
Skew Control of a Container Crane
Quang Hieu Ngo,Keum-Shik Hong,Kyeong Han Kim,Yong Jeong Shin,Sang-Hei Choi 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10
This article describes the mathematical model of the 3-dimensional motions of a container crane used in the dockside of a container terminal. The container is suspended by four cables via a spreader. When the container is accelerated or affected by wind, the container will oscillate around horizontal axis (sway) or vertical axis (skew). And an accurate position control of the container is difficult to realize because of uncertain weight, inertial sway, and winds. This paper proposes a simple PID control of the skew motion based on the analysis of 3-dimensional dynamics of the container. This system uses four cylinders to increase and decrease forces in the individual cables so that the container can be affected by yaw torque to reduce the skew error. The simulation results show the effectiveness of the PID controller in controlling the skew motion in the presence of winds.
Application of Fuzzy Moving Sliding Surface Approach for Container Cranes
Quang Hieu Ngo,Ngo Phong Nguyen,Quoc Bao Truong,김경한 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.2
In this paper, we consider the fuzzy moving sliding surface anti-sway control problem for container cranes. We first introduce the dynamic model of container cranes. Then, we develop the coupled sliding surface which ensures the asymptotic stability of the closed-loop system. Based on the proposed sliding surface, we propose the continuous sliding mode control law which guarantees the reachability of the sliding variable to zero in finite time. Hence, the proposed controller first guarantees the finite-time convergence to the sliding surface and then achieves the stability of the closed-loop system in the predefined sliding surface. Besides, in order to obtain the effective gains for the proposed sliding variable, the fuzzy logic system is employed. To illustrate the efficiency of the proposed control law, simulation results are provided.
Adaptive control of an axially moving system
Quang Hieu Ngo,홍금식,정일효 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.11
The objective of this paper is to move a load hanging under a very long rope from one place to another and to suppress the transverse vibrations of the load at the end of movement by adaptive control. The disturbance affecting the gantry motion is estimated and is incorporated into the control law design. The control command is given as a function of the position and velocity of the trolley, the hoisting speed, the sway angle of the rope at the gantry side, and the estimated disturbance force. The Lyapunov function taking the form of the total mechanical energy of the system is adopted to ensure the uniform stability of the closed-loop system. Through experiments, the effectiveness of the proposed control law is demonstrated.
Adaptive Boundary Control of an Axially Moving String under the Effect of Boundary Disturbance
Quang Hieu Ngo,Quoc Chi Nguyen,Keum-Shik Hong 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
In this paper, an active vibration control of a tensioned axially moving string under the effect of boundary disturbance is investigated. The dynamics of the translating string are described by a non-linear partial differential equation coupled with an ordinary differential equation. Disturbance estimation at the boundary is performed. A time varying control in the form of right boundary transverse motions is proposed in stabilizing the transverse vibrations of the translating continuum. A control law based on Lyapunov method is derived. Exponential stability of the closed-loop system is verified. The effectiveness of the proposed controller is shown through simulations.
Autonomous Offshore Container Crane System Using a Fuzzy-PD Logic Controller
Ngo Phong Nguyen,Trong Nghia Phan,Quang Hieu Ngo 제어로봇시스템학회 2016 제어로봇시스템학회 국제학술대회 논문집 Vol.2016 No.10
A Fuzzy-PD control strategy for an offshore container crane is investigated in this study. The offshore crane is used to handle containers between a mega container ship (called the “mother ship”) and a smaller ship (called the “mobile harbor”), which is equipped with container crane. The concept of the mobile harbor is a floating form that has the capability of transferring cargo to the local harbor from a large ship that is anchored in a nearby sea, thereby minimizing the port congestion and also eliminating the need of expanding outwards. The control objective during the loading and unloading process is to keep the payload in the desired region in the presence of ship motions. A new control strategy which is a combination of a Fuzzy controller, PD controller and compensation mechanism, is proposed as well. A Fuzzy controller plays a main role in creating the appropriate voltage, based on the dynamics and knowledge of an experienced designer, for guarantees not only prompt suppression of load swing but also accurate control of container crane position. In addition, a classical PD controller is used to tune the value of state variables into suitable range before becoming the inputs of the fuzzification process. This control scheme guarantees the stability of the closed-loop system. Simulation and experimental results are provided to verify the effectiveness of the proposed control system for offshore container cranes.