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31.
This paper addresses the problem of simultaneous depth tracking and attitude control of an underwater towed vehicle. The system proposed uses a two-stage towing arrangement that includes a long primary cable, a gravitic depressor, and a secondary cable. The towfish motion induced by wave driven disturbances in both the vertical and horizontal planes is described using an empirical model of the depressor motion and a spring-damper model of the secondary cable. A nonlinear, Lyapunov-based, adaptive output feedback control law is designed and shown to regulate pitch, yaw, and depth tracking errors to zero. The controller is designed to operate in the presence of plant parameter uncertainty. When subjected to bounded external disturbances, the tracking errors converge to a neighbourhood of the origin that can be made arbitrarily small. In the implementation proposed, a nonlinear observer is used to estimate the linear velocities used by the controller thus dispensing with the need for costly sensor suites. The results obtained with computer simulations show that the controlled system exhibits good performance about different operating conditions when subjected to sea-wave driven disturbances and in the presence of sensor noise. The system holds promise for application in oceanographic missions that require depth tracking or bottom-following combined with precise vehicle attitude control. 相似文献
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Many underwater intervention tasks are today performed using manned submersibles or remotely operated vehicles in teleoperation mode. Autonomous underwater vehicles are mostly employed in survey applications. In fact, the low bandwidth and significant time delay inherent in acoustic subsea communications represent a considerable obstacle to remotely operate a manipulation system, making it impossible for remote controllers to react to problems in a timely manner.Nevertheless, vehicles with no physical link and with no human occupants permit intervention in dangerous areas, such as in deep ocean, under ice, in missions to retrieve hazardous objects, or in classified areas. The key element in underwater intervention performed with autonomous vehicles is autonomous manipulation. This is a challenging technology milestone, which refers to the capability of a robot system that performs intervention tasks requiring physical contacts with unstructured environments without continuous human supervision.Today, only few AUVs are equipped with manipulators. SAUVIM (Semi Autonomous Underwater Vehicle for Intervention Mission, University of Hawaii) is one of the first underwater vehicle capable of autonomous manipulation.This paper presents the solutions chosen within the development of the system in order to address the problems intrinsic to autonomous underwater manipulation. In the proposed approach, the most noticeable aspect is the increase in the level of information transferred between the system and the human supervisor.We describe one of the first trials of autonomous intervention performed by SAUVIM in the oceanic environment. To the best knowledge of the authors, no sea trials in underwater autonomous manipulation have been presented in the literature. The presented operation is an underwater recovery mission, which consists in a sequence of autonomous tasks finalized to search for the target and to securely hook a cable to it in order to bring the target to the surface. 相似文献
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????????????????????????????????????????????????????????????????????????????????????????????????????У?1??????????????????????e -1.5????????????(<20 km)?????(>20 km)?????????????;2????????????????????????????????????????1?????????????????Ч????????У???????Щ???????????ε???Ч???3???????S???????????????????????P???????С,?????????????????в???????й?? 相似文献
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以实例介绍了砖混结构楼房的控制爆破拆除技术,对楼房拆除爆破的坍塌方式、爆破参数及安全技术进行了分析和探讨。 相似文献
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Xian-Kang Zhang Zhuo-Xin Yang Yu-Chun Yang Jian Yang Jian-Li Song Ping Zhao 《地震学报(英文版)》1995,8(4):519-529
In this paper, the theory and method, obtaining the tomographic determination of three-dimensional velocity structure of the
crust by use of the joint inversion of explosion and earthquake data, are given. The velocity distribution of the crust is
regarded as a continuous function of the spatial coordinates without parametrization of the velocity model ahead, so that
the inversion solution would not be influenced by different parametrization procedures. The expressions of integration kernels,
which relates the two kinds of data sets, are also given. The authors have processed the observed data in Tangshan earthquake
region by the method proposed in this paper, and obtained the tomographic results of the middle and upper crust structures
in this region. The comparison of these results with the result obtained only by the explosion data, has also been made. 相似文献