The effects of shipboard steering machinery dynamics on rudder roll stabilization systems. PDF
Preview The effects of shipboard steering machinery dynamics on rudder roll stabilization systems.
NAVAL POSTGRADUATE SCHOOL Monterey California , THESIS THE EFFECTS OF SHIPBOARD STEERING MACHINERY DYNAMICS ON RUDDER ROLL STABILIZATION SYSTEMS by Michael \V. Wcndcl September 1991 Thesis Advisor Louis V. Schmidt 1259272 Approved for public release; distribution is unlimited. L'nclassified Security classification of this pr.ge REPORT DOCUMENTATION PACT. la Report Security Classification Unclassified lb Restrictive Markings 2a Sccuntv Classification Authority 3 Distribution Availability of Report b Declassification Downcradins Schedule Approved for public release; distribution is unlimited i Pcrfi rrr.in? Organization Report Numbej(s) 5 Monitonns Organization Report Number!s^ 6a Name of Performing Organization 6b Olfice Symbol 7a Name of Monitoring Organization Naval Postgraduate School (ifapplicable) 34 Naval Postgraduate School 6c Address (cir,\ state, and ZIP code) 7b Address (citv, state, and ZIPcode) Monterev, CA 93943-5000 Monterey, CA 93943-5000 Sa Name of Funding Sponsoring Organization Sb Oiiice Symbol 9 Procurement Instrument Identification Number (ifapplicable) Sc Address (city, state, and ZIP code) 10 Source of Funding Numbers Program Element No Proieci No Task No Work L'nit Accession No u Title (includesecure classification) THE EFFECTS OP SHIPBOARD STEERING MACHINERY DYNAMICS ON REDDER ROLL STABILIZATION SYSTEMS 12 Personal Author(s) Michael YV. Wendel 13a 1 ype of Report 13b Time Covered 14 Date of Report (year, month, day) 15 Page Count Master's Thesis From To September 1991 31 16 Supplementary Notation The views expressed in tliis thesis arc those of the author and do not reflect the official policy or po- sition of the Department of Defense or the U.S. Government. Cos.r.i Codes 18 Subject Terms (continue on reverse Ifnecessary andIdentify by block number) Field Group Subgroup rudder roll stabilization 19 Abstract (continue on reverse ifnecessary andidentify by block number) The surface ship rolling motion equation is modeled as a second order system, with a natural frequency of a>n = 0.4/ sec and a dimensionless damping ratio of£ = 0.08. The model is subjected to a random forcing function, winch has a Gaussian probability distribution and can be considered as "wlute noise", and placed into State-Space form. State variable feedback of roll rate is applied and the system discrctized to match digital control. Roll angle time histories are developed for a range of feedback gains and compared. Additionally, steering machinery dynamics are modeled by a first order system and time con- stants varied to determine the effects ofrudder dynamics on the feedback system. 20 Distribution/Availability ofAbstract 21 Abstract Security Classification E D unclassified/unlimited same as report DTIC users Unclassified 22a Name of Responsible Individual 22bTelephone (includeArea code) 22c Office Symbol Louis V. Schmidt (408) 646-2768 54SS 3D FORM 1473,84 MAR 83 APR edition may be used until exhausted security classification ofthis page All other editions are obsolete Unclassified Approved for public release; distribution is unlimited. The Effects of Shipboard Steering Machinery Dynamics on Rudder Roll Stabilization Systems by Michael W. Wcndcl Lieutenant, United States Navy B.S., Villanova University, 19S4 Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN MECHANICAL ENGINEERING from the NAVAL POSTGRADUATE SCHOOL September 1991 J J // • * . . 7f " Anthony J. Hca/fpy, Chairman, Department of Mechanical Engineering ABSTRACT The surface ship rolling motion equation is modeled as a second order system, with a natural frequency of con — 0.4/.sec and a dimcnsionless damping ratio of £ = 0.08. The model is subjected to a random forcing function, which has a Gaussian probability dis- tribution and can be considered as "white noise", and placed into State-Space form. State variable feedback ofroll rate is applied and the system discretized to match digital con- trol. Roll angle time histories are developed for a range offeedback gains and compared. Additionally, steering machinery dynamics are modeled by a first order system and time constants varied to determine the effects ofrudder dynamics on the feedback system. VI TABLE OF CONTENTS INTRODUCTION I. 1 VESSEL DYNAMIC MODELING II. 3 A. MODEL OF VESSEL DYNAMICS 3 STATE-SPACE EQUATION B. 5 DISCRETIZATION C. 5 FEEDBACK D. 6 RUDDER CONTROL MODEL E. 7 THE COMPLETE SYSTEM F. 9 RESULTS III. 10 A. FEEDBACK EFFECTS 11 STEERING SYSTEM EFFECTS B. 13 CONCLUSIONS AND COMMENTS IV. 19 APPENDIX THE INVERSE PROBLEM 20 LIST OF REFERENCES 21 INITIAL DISTRIBUTION LIST 22 IV
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