Umer Hameed Shah

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

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 rods fissile material. A new command-shaping method for suppression of the flexible rods 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 rods 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.

Command-shaping control of quayside cranes with eight-pole reeving mechanism

This paper discusses the residual vibration control problem of an eight-pole quayside container crane. The main purpose of the quayside crane is loading and un-loading of the containers from container ships, arriving at the container terminal, quickly while ensuring the safety of the shipments (containers), the machinery, and the personnel at the port. The residual vibrations of the containers, as they are transported to the target locations within the port, cause operational delays and therefore must be suppressed. In this paper, an open-loop control is utilized in transporting the containers to the desired locations while suppressing their residual vibrations. The actual hoisting mechanism of the quayside crane is considered in developing its mathematical model and in generating the shaped trolley-drive commands. Simulations were performed to demonstrate the validity of the proposed control laws.

Vibration control of a nuclear fuel rod maneuvering under water

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 Hamiltons 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 rods vibrations.

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

Abstract 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.

Dynamics and control of an overhead shuttle transport system

This paper discusses the dynamics and control problem of an overhead shuttle transport system (STS), which is one of automated container handling equipment in the terminal at a port. The main purpose of the STS is the automated transport function of containers within the port in minimum time, which also requires high precision and safety. A major difference between the STS and a container crane is the configuration of the cables for holding the spreader. A mathematical model of the STS is developed in this paper, which results in an eight-pole system. Also, an open loop control is investigated in the way that the derived command for the overhead shuttle yields the minimum possible sway of the payload. Simulation results show that the vibration suppression capability of the STS is superior to the conventional overhead container crane, which is partially due to the cable configuration.

Modeling and control of a nuclear power plant's fuel transport system

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 in the fuel building or vice versa. The fuel rods must be transported under water to avoid radiation leaks to 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 the present study, a distributed parameter model of the FTS, using the Hamiltons 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 minimum vibrations. The residual vibrations of the fuel rod are controlled while considering the effects of the hydrodynamic force imposed by the surrounding water. Simulation results show that the proposed velocity command transports the fuel rods to the target location quickly resulting in a significant decrease in the rods vibrations.

Residual Vibration Suppression of an Under-water Fuel Transport System

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 systems 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 rods 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.

Command shaping for suppression of end-point oscillations of a circular cylinder maneuvering under-water

This paper discusses the command shaping technique for suppression of end-point oscillations (residual vibrations) of a circular cylinder transported under-water. Experimentation has been carried out to study the dynamic response of the cylinder by transporting it in still water following a straight path with a constant velocity, showing that the cylinder exhibits end-point oscillations at the target location. In this paper, the end-point oscillations have been simulated to match the experimental response, giving the information required for designing the command shaping control. Shaped velocity profiles have been generated using command shaping to transport the trolley, and it has been validated by experimentation that end-point oscillations have effectively been suppressed by using the command shaping technique.

Residual vibration control of a nuclear refueling machine

This paper addresses the vibration control problem of a nuclear refueling machine (RM) that transports fuel rods to given reactor locations in water. First, Hamiltons principle is used in developing a hybrid lumped-mass and distributed-parameter model of the RM to investigate the underwater vibrations of the fuel rods caused by the RMs movements. In deriving the control law, the hydrodynamic force acting on the rod is considered nonlinear. Then, a boundary control scheme is developed, which suppresses the transverse vibrations of the rod in the course of its transportation. Furthermore, Lyapunov-based stability analysis is performed to prove the uniform ultimate boundedness of the closed-loop system, considering the influence of nonlinear hydrodynamic forces on the fuel rod. Finally, simulated rod responses are shown to demonstrate the effectiveness of the proposed control scheme.

Modeling and residual vibration control of a quayside container crane

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.