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An offshore vessel with a dynamic positioning system (DP system) needs fast response to produce thrust to counteract the environmental forces acting on it for the purpose of maintaining its position and heading as close as possible to the working position. Therefore, quick and effective modulation of the thrust is the problem to determine the thrust and the rotation angle of the thruster devices of the ship. This paper presents an effective optimum control for a thruster system, using the sequential quadratic method to achieve economical and effective modulation of the thrust and the direction of the thruster. An optimum control study of a 2280 tons DP coring vessel with five rotary azimuth thruster marine positioning is studied in detail, which can quickly and exactly estimate the thrusts and angles of direction of all the thrusters. The results can provide a valuable thruster system for a dynamically positioned vessel. 相似文献
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Unmanned Underwater Vehicles (UUVs) are increasingly being used in advanced applications that require them to operate in tandem with human divers and around underwater infrastructure and other vehicles. These applications require precise control of the UUVs which is challenging due to the non-linear and time varying nature of the hydrodynamic forces, presence of external disturbances, uncertainties and unexpected changes that can occur within the UUV’s operating environment. Adaptive control has been identified as a promising solution to achieve desired control within such dynamic environments. Nevertheless, adaptive control in its basic form, such as Model Reference Adaptive Control (MRAC) has a trade-off between the adaptation rate and transient performance. Even though, higher adaptation rates produce better performance they can lead to instabilities and actuator fatigue due to high frequency oscillations in the control signal. Command Governor Adaptive Control (CGAC) is a possible solution to achieve better transient performance at low adaptation rates. In this study CGAC has been experimentally validated for depth control of a UUV, which is a unique challenge due to the unavailability of full state measurement and a greater thrust requirement. These in turn leads to additional noise from state estimation, time-delays from input noise filters, higher energy expenditure and susceptibility to saturation. Experimental results show that CGAC is more robust against noise and time-delays and has lower energy expenditure and thruster saturation. In addition, CGAC offers better tracking, disturbance rejection and tolerance to partial thruster failure compared to the MRAC. 相似文献
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As an extremely significant tool, autonomous underwater vehicles (AUVs) obtain corresponding development which is widely used in the oceanographic survey, military applications and ocean investigation. However, it is rather hard to fulfill missions about ocean exploration in suspended status or at slow speeds for traditional AUVs, due to the effect of the control surfaces trends to decline or even invalid completely in this condition. To overcome the limitation mentioned above, a torpedo-shaped AUV with vectored thrust ducted propeller is presented in this paper, in which the vector thruster is designed based on a 3SPS-S parallel manipulator. The 3SPS-S parallel manipulator, which has merits of compact structure, high reliability, high precision and fast response, is employed for thrust vectoring control mechanism. Additionally, the kinematics and dynamics model of the thrust-vectoring mechanism is constructed, and the MATLAB simulation results show the designed vectored thruster have great application superiority and potential for AUV. Finally, a control scheme of the vectored thruster is designed after considering the case study. The main idea of this paper lies in describing a novel design of the vectored thruster AUV based on 3SPS-S parallel manipulator, which can complete the mission at zero or slow forward speeds. 相似文献
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以FLUENT6.1软件为工具,利用湍流k-ε模型,求解二维稳态可压缩N-S方程,模拟了微喷管内的超音速流动,分析了喷管喉部结构不对称对喷管流场与喷管出口推力的影响。这种喉部结构不对称由于喉部上下顶点在x方向上偏离一定距离所造成。数值计算结果表明,喷管喉部上下顶点在流体流动方向的不对称,将导致喷管内部流体流场不平衡性,诱导喷管内部产生康达效应,使得喷管出口的x方向推力减小,y方向产生了多余的推力。 相似文献
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针对自治水下机器人(Autonomous underwater vehicle,AUV)推力器布置和控制仿真的困难性及以往电机仿真难以进行的缺点,提出1种进行多推力器运动仿真的方法,该方法建立的模型克服了推力器推力控制系统不能与电机结合的问题,能较好地反映推力器布置和电机的响应情况,可为AUV的运动控制、布置设计及控制系统开发等提供验证模型.针对流线型AUV CRanger-2的推力器布置情况,在对其建立推力器模型的基础上,利用模型对设定推力下的推力器控制进行仿真.仿真结果表明:该方法能够有效地模拟推力器布置既定情况下的电机运动与推力控制,可为水下机器人控制策略优化提供仿真平台. 相似文献
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Flapping wings located beneath or to the side of the hull of the ship are investigated as unsteady thrusters, augmenting ship propulsion in waves. The main arrangement consists of horizontal wing(s) in vertical oscillatory motion which is induced by ship heave and pitch, while rotation about the wing pivot axis is actively controlled. In this work we investigate the energy extraction by the system operating in irregular wave conditions and its performance concerning direct conversion to propulsive thrust. More specifically, we consider operation of the flapping foil in waves characterised by a spectrum, corresponding to specific sea state, taking into account the coupling between the hull and the flapping foil dynamics. The effect of the wavy free surface is accounted for through the satisfaction of the corresponding boundary conditions and the consideration of the wave velocity on the formation of the incident flow. Numerical results concerning thrust and power coefficients are presented, indicating that significant thrust can be produced under general operating conditions. The present work can be exploited for the design and optimum control of such systems extracting energy from sea waves for augmenting marine propulsion in rough seas, with simultaneous reduction of ship responses offering also dynamic stabilisation. 相似文献
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本文提出了安装有槽道螺旋桨的潜器的速升率计算方法。因为航速对槽道桨发出的推力和力矩大小具有很大的影响，所以在速升率计算公式中应当引入对力臂的修正项。数值计算表明，计入该项修正能显著改善装有槽道桨潜器速升率的预报值。 相似文献
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