Open-Loop Vibration Control of an Underwater System: Application to Refueling Machine

Shah, Umer Hameed,Hong, Keum-Shik,Choi, Sang-Hei IEEE 2017 IEEE/ASME transactions on mechatronics Vol.22 No.4

<P>This paper addresses a residual vibration control problem of the refueling machine (RM) that transports fuel rods in water to their desired locations in the nuclear reactor. A hybrid lumped-mass and distributed-parameter model of the RM is considered for investigation of the transverse vibrations (caused by trolley movement) of a fuel rod in water. Simulations and experiments reveal that the hydrodynamic force causes a large deflection of the rod in water as compared with in air, which must be suppressed to avoid damage to the rod's fissile material. A new command-shaping method for suppression of the flexible rod's residual vibrations in water is developed, which considers both a similitude law relating the maximum endpoint deflection of the rod in water to the maximum trolley velocity and a constraint on the rod's maximum endpoint deflection during its transport. The simulation and experimental results show that the proposed underwater-command-shaping method can effectively suppress the vibrations of the flexible rod operating in water.</P>

Dynamic Response of an Under-water Fuel Transfer System

Umer Hameed Shah,Mingxu Piao,Jae Young Jeon,Keum-Shik Hong 제어로봇시스템학회 2013 제어로봇시스템학회 국제학술대회 논문집 Vol.2013 No.10

This paper discusses the dynamic response of a fuel transfer system that is supposed to transport fuel rods under-water. The under-water fuel transfer system is usually utilized in the process industry and in deep sea for oil transportation from the exploration sites. In both the cases fuel transfer system is exposed to environmental disturbances which define its dynamic response and are detrimental to system’s performance. It is therefore, necessary to study the dynamic response of such a system for its desired application. This paper discusses the problem of studying the dynamic response of a fuel carrying rod that travels along a straight path from one position to another with maximum speed so that, when it reaches the desired position, there is minimal residual vibration (sway). A mathematical model is derived for the system, considering the effects of hydrodynamic forces acting on the fuel carrying rod. An experiment is also conducted to study the dynamic behavior of the rod while it travels under-water and the residual vibrations (sway) at the end point are suppressed using the input shaping technique.

Dynamic Analysis and Control of Under-water Refueling Rod Using Input Shaping Technique

Umer Hameed Shah,Mingxu Piao,Jae Young Jeon,Keum-Shik Hong 제어로봇시스템학회 2013 제어로봇시스템학회 국내학술대회 논문집 Vol.2013 No.5

Input shaping control of a nuclear power plant’s fuel transport system

Shah, Umer Hameed,Hong, Keum -Shik Springer-Verlag 2014 Nonlinear dynamics Vol.77 No.4

Residual Vibration Suppression of an Under-water Fuel Transport System

Umer Hameed Shah,Mingxu Piao,Jae Young Jeon,Keum-Shik Hong 제어로봇시스템학회 2014 제어로봇시스템학회 국제학술대회 논문집 Vol.2014 No.10

This paper discusses the residual vibration suppression problem of a nuclear fuel transport system (FTS). The FTS is supposed to transport the fuel rods under-water to the desired locations within the plant in the minimum possible time. It has been observed that the rods oscillate at the end of such brisk maneuvers causing an undesirable delay in the operation, and affecting the system’s performance in terms both of productivity and of safety. In this case, input shaping can be used to generate shaped command profiles to transport the rods to the target position with minimum residual vibrations, however, due to the under-water maneuver the process becomes damped and input shaping becomes ineffective. Recently, a modified shaped command has been proposed based on the zero vibration (ZV) shaper, which effectively suppresses the rod’s residual vibrations in the presence of the hydrodynamic forces. In this paper, the said command is experimentally investigated with variations in its structure in order to get an insight into its capability of suppressing residual vibrations effectively.

Vibration Control of a Nuclear Fuel Rod Maneuvering Under Water

Umer Hameed Shah,Mingxu Piao,Gyoung-Hahn Kim,Keum-Shik Hong 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10

This paper addresses the vibration control problem of a fuel transport system (FTS) in a nuclear power plant. The FTS transports the fuel rods in the nuclear reactor to desired locations within the fuel building. The fuel rods must be transported under water to avoid radiation leaks into the environment. It has been observed that a quick maneuver of the trolley can cause vibrations that can damage the structure of the fuel rods, due to the hydrodynamic force exerted by the surrounding fluid. In this study, a distributed parameter model of the FTS, using the extended Hamilton’s principle, is developed. The developed model is verified with experiments. A velocity command is designed, as an open-loop control, to transport the fuel rods in quick time to the target locations with minimal vibrations. The residual vibrations of the fuel rod are controlled while considering the effects of the hydrodynamic force imposed by the surrounding water. Simulation and experimental results show that the proposed velocity command transports the fuel rods to the target location quickly resulting in a significant decrease in the rod’s vibrations.

Active Vibration Control of a Flexible Rod in Water

Umer Hameed Shah,Mingxu Piao,Gyoung-Hahn Kim,Keum-Shik Hong 제어로봇시스템학회 2017 제어로봇시스템학회 국제학술대회 논문집 Vol.2017 No.10

This paper addresses the vortex-induced vibration (VIV) suppression problem of nuclear fuel rods, which are transported by a refueling machine (RM) to given reactor locations in water. First, Hamilton’s principle is used to develop the equations of coupled motions of the RM and the fuel rod. The resulting equations of the hybrid (lumped-mass RM and distributed-parameter flexible rod) system are then utilized to investigate the VIVs of the fuel rod upon the movements of the RM. Then, a boundary control scheme is developed to suppress the VIVs of the rod in the course of its transportation in water. Furthermore, Lyapunov function-based stability analyses are performed to prove the uniform ultimate boundedness of the closed-loop system, considering the influence of the nonlinear hydrodynamic force acting on the fuel rod. Finally, simulations are performed to demonstrate the effectiveness of the proposed boundary control scheme.

Active vibration control of a flexible rod moving in water: Application to nuclear refueling machines

Shah, Umer Hameed,Hong, Keum-Shik Elsevier 2018 Automatica Vol.93 No.-

<P><B>Abstract</B></P> <P>This paper addresses a simultaneous control of the positions of the bridge and trolley and the vibrations of the load of a nuclear refueling machine (RM) that transports nuclear fuel rods to given locations in the nuclear reactor. Hamilton’s principle is used to develop the equations of motion of the RM. The lateral and transverse vibrations of the fuel rods during their transportation in water are analyzed. In deriving the control law, the nonlinear hydrodynamic forces acting on the rod are considered. Then, a boundary control scheme is developed, which suppresses the lateral and transverse vibrations simultaneously in the course of the transportation of the fuel rod to the desired locations. Furthermore, Lyapunov function-based stability analyses are performed to prove the uniform ultimate boundedness of the closed loop system as well as the simultaneous control of the positions of the bridge and trolley under the influence of nonlinear hydrodynamic forces. Finally, experimental and simulation results are provided to demonstrate the effectiveness of the proposed control scheme.</P>

Dynamics and Vibrational Control of an Underwater Inverted Pendulum

Saqib Hasnain,Umer Hameed Shah,Sang-Hei Choi,Keum-Shik Hong 제어로봇시스템학회 2016 제어로봇시스템학회 국제학술대회 논문집 Vol.2016 No.10

This paper discusses the dynamics and vibrational control problem of an underwater inverted pendulum system. The system’s equations of motion are obtained by using the Lagrange equation. The vibrational control technique is applied to stabilize the inverted pendulum in water. Furthermore, stability analyses in terms of stable-unstable region for the underwater inverted pendulum system is presented. While a number of control techniques for the stabilization problem of an inverted pendulum in air by oscillating the support point have been developed, but a similar technique for the system in water has not yet been investigated. The dynamics of any system in liquid is strongly influenced by the density of the liquid and the relative velocity of the surrounding liquid. Also, it becomes a challenging task to stabilize the system in the presence of the hydrodynamic forces acting on it. Simulation results reveal that the application of the vibrational control technique newly developed in this paper can successfully stabilize the system in water under the influence of hydrodynamic forces.

Modeling and Residual Vibration Control of a Quayside Container Crane

Mingxu Piao,Umer Hameed Shah,Sang-Hei Choi,Keum-Shik Hong 제어로봇시스템학회 2016 제어로봇시스템학회 국제학술대회 논문집 Vol.2016 No.10

This paper discusses the mathematical modeling and residual vibration control problem of a quayside container crane, which is one of the automated handling equipment for containers at a seaport. The main purpose of the quayside crane is the safe loading and un-loading of the container ships in quick time. The residual vibrations of the transported containers cause operational delays and therefore must be suppressed, which can be achieved by implementing an appropriate control strategy. Generally, the control strategies are based on a simplified model of a conventional container crane (i.e., assuming a single-rope hoisting mechanism). However, in this paper, we have derived the mathematical model of the quayside crane based on the actual (i.e., multi-rope) hoisting mechanism. An open-loop control is then applied to generate shaped trolley-drive commands to transport the containers to the desired locations while suppressing their residual vibrations. Furthermore, a closed loop control is also developed to suppress the vibrations of the containers due to initial conditions and disturbances. The validity of the proposed control laws has been demonstrated by performing simulations.