Command Shaping for Sloshing Suppression of a Suspended Liquid Container

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Abdullah Alshaya ◽  
Khalid Alghanim
Keyword(s):  
Liquid Sloshing ◽  
Command Shaping ◽  
Equivalent Mechanical Model ◽  
Proposed Model ◽  
Sloshing Dynamics ◽  
Time Optimal ◽  
Free Surface Wave ◽  
Liquid Depth ◽  
Mass Spring ◽  
Input Command

Abstract The residuals of liquid free-surface wave oscillations induced by a rest-to-rest crane maneuver of a suspended liquid container are eliminated using a command-shaped profile. The dynamics of liquid sloshing are modeled using an equivalent mechanical model based on a series of mass-spring-damper systems. The proposed model considers the excited frequencies of the container swing motion and liquid sloshing modes. The objective is to design a discrete-time shaped acceleration profile with a variable command length that controls the moving crane-jib, while suppressing the sloshing modes. Simulations are conducted to illustrate the command effectiveness in eliminating liquid sloshing with a wide variation range of system and command-designing parameters; liquid depth, cable length, command duration, and the employing of higher sloshing modes in representing the sloshing dynamics. The command sensitivity of the input command to changes of the system parameters are treated as well. A refined and smooth input command based on suppressing the residuals of multimodes is also introduced. Furthermore, the command effectiveness was supported by a comparison with the time-optimal flexible-body control and multimode zero vibration input shaper.

A smooth polynomial shaped command for sloshing suppression of a suspended liquid container

2020 ◽  
pp. 014233122094930
Author(s):  
Abdullah Alshaya ◽  
Dima Almujarrab
Keyword(s):  
Vibrational Modes ◽  
Governing Equations ◽  
Equivalent Mechanical Model ◽  
Proposed Model ◽  
Sloshing Dynamics ◽  
Liquid Depth ◽  
Mass Spring ◽  
Pendulum Dynamics ◽  
Multi Mode ◽  
Sloshing Suppression

A smooth polynomial shaped command with an adjustable command time length is proposed for eliminating the residual vibrations of a multi-mode system. The ability of eliminating jerks and vibrational modes, regardless of their number, offers the most advantage of the proposed command. A numerical simulation is conducted to test the command’s effectiveness by eliminating the residual sloshing oscillations of a liquid-filled container conveyed by an overhead crane in a rest-to-rest manoeuvre. The governing equations of the liquid free-surface level are derived by modelling the sloshing dynamics by a series of mass–spring–damper harmonics. The proposed model accounts for the coupling between the pendulum dynamics and the sloshing equivalent mechanical model. The command’s robustness to the system parameters’ uncertainties, liquid depth and cable length, are investigated as well. The ability of adjusting the command length and retaining higher sloshing modes in command-designing are also outlined.

Robust multi-steps input command for liquid sloshing control

2021 ◽  
pp. 107754632110177
Author(s):  
Abdullah Alshaya ◽  
Adel Alshayji
Keyword(s):  
Liquid Sloshing ◽  
Flexible Body ◽  
Transient Vibration ◽  
Resonant Frequencies ◽  
System Parameters ◽  
Input Shaper ◽  
Body Dynamics ◽  
Time Optimal ◽  
Multi Body ◽  
Input Command

A robust input command based on multiple steps for eliminating the residual vibrations of a multimode linear system is proposed. Only the system resonant frequencies are needed to determine the step magnitudes in the shaped command. The command duration is selectable to help in designing an optimum command that compensates between the reduction in the transient vibration, the enhancement in the command robustness, and the increase in the total maneuver time. The induced transient and residual sloshing oscillations of a suspended water-filled container are suppressed using the proposed command. The dynamics of the sloshing is numerically simulated using finite element method that accommodates the interactions between the fluid, structural, and multi-body dynamics. A short move time penalty is incurred with the price of significant reduction in the liquid sloshing. The performance of the shaped command to the system parameters and the robustness to their uncertainty are investigated. An improved robust input command in the presence of uncertainties in the cable length and water depth is also introduced. The effectiveness and excellence of the proposed command is demonstrated through a comparison with multimode zero-vibration input shaper and time-optimal flexible-body control.

scholarly journals A numerical study: liquid sloshing dynamics in a tank due to uncoupled sway, heave and roll ship motions

2013 ◽  
Vol 10 (2) ◽  
pp. 119-138 ◽  
Author(s):  
Nasar Thuvanismail ◽  
Sannasiraj Sannasi ◽  
Sundar Vallam
Keyword(s):  
Numerical Study ◽  
Energy Spectra ◽  
Qualitative Assessment ◽  
Ship Motions ◽  
Theoretical Studies ◽  
Sloshing Dynamics ◽  
Tank System ◽  
Liquid Depth ◽  
Sloshing Phenomenon ◽  
Heave Motion

In order to explore the physics implicated with the sloshing phenomenon subjected to independent regular sway, heave and roll excitations of the liquid tank system, theoretical studies are carried out. Four liquid fill levels with static liquid depth, hs, to the length, l of aspect ratio (hs/l) 0.163, 0.325, 0.488 and 0.585, are considered. The energy spectra of sloshing oscillation, their qualitative assessment and the harmonics present in the sloshing oscillation are studied. Frequency –Response amplitude has also been presented. The study reveals that sway excites a particular mode of sloshing (primary harmonic) by fulfilling the resonance conditions and also excites secondary modes. However, the roll motion excites the first mode of sloshing irrespective of the excitation frequencies. The heave motion excites the particular mode which is assumed as an initial perturbation.DOI: http://dx.doi.org/10.3329/jname.v10i2.16215 

scholarly journals A New Nonlinear Active Disturbance Rejection Control for the Cable Car System to Restrain the Vibration

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Xinyan Hu ◽  
Lina Li
Keyword(s):  
Disturbance Rejection ◽  
System Model ◽  
Active Disturbance Rejection Control ◽  
Active Disturbance Rejection ◽  
The People ◽  
Disturbance Rejection Control ◽  
Proposed Model ◽  
Spring System ◽  
Linear Invariant ◽  
Mass Spring

The safety of the cable car system is very important for the lives of the people. But, it is easily affected by the environment such as the wind which causes the cable car system to have strong vibration disturbance, thus degrading the safety of the cable car system. In this paper, a new nonlinear active disturbance rejection control (ADRC) is proposed to restrain the vibration of the cable car. First, a new two-mass-spring system model is utilized to establish the cable car system model. The new translation vibration nonlinear model is derived by a linear-invariant two-mass-spring system. Then, a special nonlinear fal• is designed to restrain the vibration, and a new high-order nonlinear ADRC is presented for the cable car system. Finally, simulation results verify the feasibility and accuracy of the proposed model.

Mitigation of liquid sloshing in a rectangular tank due to slotted porous screen

2020 ◽  
Vol 234 (3) ◽  
pp. 686-698
Author(s):  
Sunny Kumar Poguluri ◽  
Il-Hyoung Cho
Keyword(s):  
Free Surface ◽  
Numerical Technique ◽  
Liquid Sloshing ◽  
Tank Wall ◽  
Air Entrapment ◽  
Jet Formation ◽  
Induced Motion ◽  
Free Surface Wave ◽  
Nonlinear Free Surface ◽  
Porous Screen

Liquid sloshing inside a tank with a slotted porous screen at the center is studied based on numerical and experimental methods. Slotted screens with three different porosities (0.0964, 0.1968 and 0.3022) for two submergence depths of 1 and 2 cm have been considered. One of the main advantages of the slotted screens is that the resonance frequency of the sloshing tank can be altered and the sloshing-induced motion/load can be suppressed by energy dissipation across the porous screen. The complexities of slotted screens equipped in a sloshing tank are accompanied by wave breaking, jet formation and liquid fragmentations which are commonly seen phenomena across the porous screen. These violent free surface behaviors in a tank are studied based on numerical simulations using the incompressible turbulent model and compared with the experiments. For the numerical sloshing tank with porous screen, free surface elevation and pressure at the tank wall are in good agreement with the experimental results. The adopted numerical technique will be able to capture the nonlinear free surface wave profile, air entrapment and jet formation across the screen in agreement with the experiments. For the fully submerged screen, the lowest resonance period shifted slightly to higher values. The sloshing tank equipped with porous screen of 0.1968 for the fully submerged screen predicted lower values of the amplification factor and pressure at the tank wall compared to other cases.

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