Effects of Hull and Control Surface Roughness on Ship Maneuvering

2020 ◽  
pp. 1-10
Author(s):  
John C. Daidola
Keyword(s):  
Surface Roughness ◽  
Equations Of Motion ◽  
Control Surface ◽  
Ship Maneuvering ◽  
Single Screw ◽  
Operation And Maintenance ◽  
Hydrodynamic Derivatives ◽  
Turning Maneuver ◽  
And Control ◽  
Surface Vessel

The effects of hull roughness on ship maneuvering characteristics are investigated. The hydrodynamic derivatives in the equations of motion for surface vessel maneuvering are modified to incorporate roughness of the hull and rudder. Vessel lifetime roughness profiles are postulated based on construction, coatings, operation, and maintenance for a vessel life of 25 years. These are then applied to the turning maneuver for single screw cargo ships with block coefficients from .60 to .80. The implications for naval missions are discussed.

scholarly journals Fuzzy x- and s Control Charts: A Data-Adaptability and Human-Acceptance Approach

Complexity ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-17 ◽  
Author(s):  
Ming-Hung Shu ◽  
Dinh-Chien Dang ◽  
Thanh-Lam Nguyen ◽  
Bi-Min Hsu ◽  
Ngoc-Son Phan
Keyword(s):  
Surface Roughness ◽  
Control Charts ◽  
Fuzzy Numbers ◽  
Control Surface ◽  
Process Conditions ◽  
Fuzzy Data ◽  
Size Condition ◽  
Resolution Identity ◽  
And Control ◽  
Control Limits

For sequentially monitoring and controlling average and variability of an online manufacturing process, x¯ and s control charts are widely utilized tools, whose constructions require the data to be real (precise) numbers. However, many quality characteristics in practice, such as surface roughness of optical lenses, have been long recorded as fuzzy data, in which the traditional x¯ and s charts have manifested some inaccessibility. Therefore, for well accommodating this fuzzy-data domain, this paper integrates fuzzy set theories to establish the fuzzy charts under a general variable-sample-size condition. First, the resolution-identity principle is exerted to erect the sample-statistics’ and control-limits’ fuzzy numbers (SSFNs and CLFNs), where the sample fuzzy data are unified and aggregated through statistical and nonlinear-programming manipulations. Then, the fuzzy-number ranking approach based on left and right integral index is brought to differentiate magnitude of fuzzy numbers and compare SSFNs and CLFNs pairwise. Thirdly, the fuzzy-logic alike reasoning is enacted to categorize process conditions with intermittent classifications between in control and out of control. Finally, a realistic example to control surface roughness on the turning process in producing optical lenses is illustrated to demonstrate their data-adaptability and human-acceptance of those integrated methodologies under fuzzy-data environments.

scholarly journals Diagonally dominant backstepping autopilot for aircraft with unknown actuator failures and severe winds

2014 ◽  
Vol 118 (1207) ◽  
pp. 1009-1038 ◽  
Author(s):  
S. Ismail ◽  
A. A. Pashilkar ◽  
R. Ayyagari ◽  
N. Sundararajan
Keyword(s):  
Dynamic Models ◽  
Controller Design ◽  
Design Method ◽  
Equations Of Motion ◽  
Control Surface ◽  
Actuator Failures ◽  
Time Scale Separation ◽  
Diagonally Dominant ◽  
Trajectory Following ◽  
And Control

Abstract A novel formulation of the flight dynamic equations is presented that permits a rapid solution for the design of trajectory following autopilots for nonlinear aircraft dynamic models. A robust autopilot control structure is developed based on the combination of the good features of the nonlinear dynamic inversion (NDI) method, integrator backstepping method, time scale separation and control allocation methods. The aircraft equations of motion are formulated in suitable variables so that the matrices involved in the block backstepping control design method are diagonally dominant. This allows us to use a linear controller structure for a trajectory following autopilot for the nonlinear aircraft model using the well known loop by loop controller design approach. The resulting autopilot for the fixed-wing rigid-body aircraft with a cascaded structure is referred to as the diagonally dominant backstepping (DDBS) controller. The method is illustrated here for an aircraft auto-landing problem under unknown actuator failures and severe winds. The requirement of state and control surface limiting is also addressed in the context of the design of the DDBS controller.

Submarine Maneuvering Simulations of ONR Body 1

2007 ◽  
Author(s):  
Ganesh Venkatesan ◽  
William Clark
Keyword(s):  
Degrees Of Freedom ◽  
Stokes Equations ◽  
Equations Of Motion ◽  
Solution Procedure ◽  
Control Surface ◽  
Computational Domain ◽  
Instantaneous Position ◽  
Sliding Interfaces ◽  
And Control ◽  
Maneuvering Simulations

The application of computational fluid dynamics method to the submarine maneuvering simulations of ONR Body 1 is presented. ONR Body 1 is an unclassified submarine radio controlled model with propeller and control surfaces. Unsteady Reynolds-averaged Naviers-Stokes equations of fluid flow is coupled to the six degrees-of-freedom equations of motion of a rigid body via user coding to predict the instantaneous position and body orientation. Propeller and control surface motions are accounted for by using the moving mesh feature integrated into the solution procedure which allows sliding interfaces between different mesh blocks of the computational domain (for propeller rotation), as well as mesh distortion (for control surface deflection). This offers the flexibility of using a single computational grid for the entire simulation period. The maneuvers simulated include a constant depth and heading run as well as a horizontal overshoot maneuver using conditions consistent with the experiment. Predicted results show favorable agreement with experimental measurements.

Determination of Bore Grinding Machine Parameters to Reduce Cycle Time

2014 ◽  
Vol 974 ◽  
pp. 413-417
Author(s):  
Salakjitt Buddhachakara ◽  
Wipawee Tharmmaphornphilas
Keyword(s):  
Surface Roughness ◽  
Cycle Time ◽  
Control Surface ◽  
Fine Grinding ◽  
Starting Position ◽  
Grinding Machine ◽  
And Control ◽  
Central Composite ◽  
New Machine

This paper applies a central composite design (CCD) to determine proper machine parameters to reduce the cycle time of a bore grinding process. There are 6 machine parameters, which are rough grinding 2 starting position, fine grinding starting position, speed of rough grinding 1, speed of rough grinding 2, speed of rough grinding 3 and speed of fine grinding and 2 types of responses, which are cycle time and surface roughness considered in this study. A half CCD is used to find the optimal machine setup parameters. The experiment shows that new machine conditions can reduce cycle time from 2.98 second per piece to 2.76 second per piece and control surface roughness within specification of 1.0 um. After implementing the new machine conditions in the real setting, we found that the average actual cycle time is 2.76 second per piece with roughness of 0.841 um.

Ship-Bank Interaction of a Large Tanker and Related Control Problems

2013 ◽  
Author(s):  
Philipp Mucha ◽  
Ould el Moctar
Keyword(s):  
Control Theory ◽  
Vertical Wall ◽  
Planar Motion ◽  
Navier Stokes ◽  
Linear Quadratic ◽  
Ship Maneuvering ◽  
Motion Mechanism ◽  
Hydrodynamic Derivatives ◽  
Planar Motion Mechanism ◽  
And Control

The objective of this work is to establish a synthesis between modern methodology in the field of ship maneuvering and control theory using the example of hydrodynamic ship-bank interactions for a large tanker. Evolving technologies have paved the way for developing increasingly sophisticated modeling techniques to study ship flows. These tecnologies have made it possible to resemble Planar Motion Mechanism (PMM) tests in numerical simulations using Reynolds-averaged Navier-Stokes (RANS) equations. These advances give way for the numerical determination of hydrodynamic derivatives as present in the maneuvering equations. This methodology is adopted in the present investigation to obtain these coefficients for various separation distances to a vertical wall. Likewise, control theory has experienced vital progress enabling engineers to apply elaborate control policies in their systems. Special attention has been payed to the distinct discipline of optimal control theory and the family of Linear Quadratic (LQ) regulators. Among the popular class of conventional Proportional-Integral-Derivative (PID) controllers rather heuristic design procedures are applied; appealing to the practitioners but might not be suitable for special applications. The work presented investigates the suitablity of deriving hydrod-namic properties by means of Virtual Planar Motion Mechanism (VPMM) tests for the KVLCC2 tanker travelling at various distances to a vertical wall of infinite depth. In subsequent maneuvering simulations the performance of the introduced controllers is discussed.

Force Based Model for Automated Surface Roughness Prediction in Slot Milling

2001 ◽  
Author(s):  
A. Sarhan ◽  
A. A. Nasr ◽  
R. M. El-Zahry
Keyword(s):  
Surface Roughness ◽  
Tool Wear ◽  
Cutting Force ◽  
Control Surface ◽  
Percentage Error ◽  
Depth Of Cut ◽  
Monitoring And Control ◽  
Slot Milling ◽  
On Line ◽  
And Control

Abstract Study was carried out to analyze the dynamic cutting signals of slot-milling process, in order to design automated on-line tool and surface roughness monitoring strategies, based on indices extracted from these signals, to automatically monitor and control surface roughness in slot milling. Especially designed and manufactured sensitive strain gage dynamometer was used to measure slot-milling radial and tangential forces during milling cycle. The dynamometer was calibrated in static and dynamic ranges. The effect of flank wear width on the magnitude of the cutting force harmonics was constructed as function of axial depth of cut, feed rate per tooth, specific cutting pressure of work material and instantaneous angle of rotation. The results were plotted at various cutting conditions in time and frequency domains. The tool wear was measured in an off-line manner using the tool maker’s microscope and interrelationships of cutting force harmonics and tool wear magnitude were constructed and were used in the computer simulation. Surface roughness was measured using surface meter (Surtronic 3+) with a portable printer. The cutting force signal harmonics were used to establish the proposed force based model to predict the surface roughness of the workpiece machined in slot-milling and examining this system by another experimental tests to define the reliability of the system and to define the percentage error of the system model. Hence, an index named as surface index (S.I) is extracted from ratio between first force amplitude at first significant frequency and first surface amplitude at the same frequency, to predict the surface roughness of the workpiece machined in slot-milling. This is to be employed in automated on-line quality management (monitoring and control) strategy.

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