碩士 / 國立中正大學 / 機械系 / 89 / The thesis is concerned with the large amplitude roll motions and capsizing of small vessels in severe sea states. An active anti-roll tank is employed as the actuator for ship roll stabilization .The anti-capsizing fuzzy sliding mode controller designed previously is followed here, with the following factors taken into account：(1).actuator dynamics；(2).state constraint (due to the limited range for the center of gravity of the ship)；(3).input saturation (due to the limited power of the pump).With the inclusion of the actuator dynamics, the overall control system is of the 4th order. Its control lows is obtained by 3 times of backstepping procedure with 3 levels of sliding mode control. Fuzzy logic is used to estimate the uncertainty''s upper bound according to the sea states. The estimate is then used for tuning the uncertainty-related parameters in each level of the sliding mode control. An admissible set for the initial states is obtained through Lyapunov analysis. It is shown that with proper control gains and with the assumption of small uncertainty estimation error, the closed-loop ship roll dynamics will be ultimately bounded for any initial state in the admissible set. In other words, the objective of anti-capsizing can be achieved even under the state and input constraints. In addition, the admissible set is shown to include the safe region for the calm water model.
Another contribution of the thesis is a quantitative analysis for the sliding mode control. It is to study the relationship between the control parameters and the performance of the closed-loop system. This quantitative study is utilized to obtain optimal control parameters for the sliding mode control system. It is shown that the optimal parameters can yield the shortest settling time with out the problem of chattering and excessive control effort.
The theoretical analysis is confirmed by the numerical analysis of an existing fishing vessel.
| Identifer | oai:union.ndltd.org:TW/089CCU00489022 |
| Date | January 2001 |
| Creators | Woei-Ren Lo, 羅偉仁 |
| Contributors | Shyh-Leh Chen, 陳世樂 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 234 |
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