23 resultados para Autonomous aerial vehicles

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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提出了一种基于扩展集员估计(ESMF)的多机器人协作观测方法,该方法将多机器人之间的观测数据融合过程嵌入到估计过程当中,从而减少了数据处理的过程,增强了算法的快速性。同时,这种方法在实现协作观测时只需要协作机器人传送观测信息而不是整个的估计信息,因此可以减轻多机器人系统的通信负担。除此之外,该方法在融合多机器人的观测数据过程中避免了多余的近似过程,增加了观测的准确性。最后,给出了三维环境下的仿真结果,验证了方法的可行性。

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地球形状的不规则性,各种导航传感器本身的误差,以及仪器的安装偏差等,使得AUV(自治水下机器人)在进行远距离自主航行时,自主导航的精度大大下降。针对以上问题及实际工程需要,论文对AUV自主导航的航位推算算法做了进一步研究并加以改进,以提高其自主导航精度。最后,利用2004年中国科学院沈阳自动化所水下机器人研究中心进行AUV湖试所获得的数据,对文中提出的算法进行了验证。结果表明,AUV的自主导航精度得到大大提高,可以用于修正原来的自主导航算法。

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对AUV(AutonomousUnderwaterVehicle)自主导航的航位推算算法做了进一步研究并加以改进,以提高其自主导航精度.然后,利用AUV湖试所获得的数据,对本文提出的修正算法进行了验证.结果表明, AUV的自主导航精度得到很大提高,可以用于修正原来的自主导航算法.

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水下环境的复杂性以及自身模型的不确定性,给水下机器人的控制带来很大困难。针对水下机器人的特点和控制方面所存在的问题,提出了基于预测 校正控制策略的水下机器人神经网络自适应逆控制结构及训练算法。通过在线辨识系统的前向模型,估计出系统的Jacobian矩阵,然后采用预报误差法实现控制器的自适应。同时,为了提高系统对于外扰的鲁棒性,在伪线性回归算法的基础上,在评价函数中引入微分项。理论分析和仿真结果表明,与原来的算法相比,微分项的引入改善了系统对于外扰的鲁棒性和动态性能。

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本文针对自治水下机器人AUVs(Autonomous Underwater Vehicles)水下工作环境、动力学建模和运动控制的特点。采用了一种基于Backstepping的鲁棒自适应控制方法,实现AUV水平侧移和航向控制,并利用AUV-CR02模型进行了仿真实验。仿真实验结果表明该控制方法的控制效果明显优于PID控制。特别是在有模型不确定和不确定环绕干扰时,表现出良好的鲁律性和自适应性。

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文章给出了水下机器人的定义 ,依据定义进行了分类 ,简要回顾了几类重要水下机器人的进展 ,指出了无人无缆自治水下机器人 (AUVs)是当今水下机器人研究与开发的热点 ,介绍了最近 2 0年沈阳自动化研究所与国内外有关单位合作 ,在水下机器人领域从无人有缆遥控水下机器人 (ROVs)到AUVs的研究开发工作 ,它从一个侧面反映了我国在这一领域的进展情况。

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本文介绍了我们承担研制的国家“863”计划1000m及6000m无缆水下机器人的回收系统.回收系统在4级海况下不用专用母船能够成功地回收水下机器人,依据母船、海况、水下机器人及其他具体情况,介绍了两种不同的回收方案和回收器,经海上试验证明是有效和可行的。

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Hypersonic vehicles represent future trends of military equipments and play an important role in future war. Thermal protection materials and structures, which relate to the safety of hypersonic vehicles, are one of the most key techniques in design and manufacture of hypersonic vehicles. Among these materials and structures, such as metallic temperature protection structure, the temperature ceramics and carbon/carbon composites are usually adopted in design. The recent progresses of research and application of ultra-high temperature materials in preparation, oxidation resistance, mechanical and physical characterization are summarized.

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High temperature chemical non-equilibrium phenomena have a great effect on the flow field around a reentry vehicle. A set of three dimensional Navier-Stokes equations have been solved by implicit finite volume NND scheme. Both ideal gas viscous flow and chemical non-equilibrium flow are calculated for a spherical-cone at a small angle of attack. The results of the two flows have been compared and the effect of chemical non-equilibrium has been analyzed. The effect of wall material's properties, such as catalysis and radiation were studied. The results are in good agreement with the referenced paper.

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A new idea of drag reduction and thermal protection for hypersonic vehicles is proposed based on the combination of a physical spike and lateral jets for shock-reconstruction. The spike recasts the bow shock in front of a blunt body into a conical shock, and the lateral jets work to protect the spike tip from overheating and to push the conical shock away from the blunt body when a pitching angle exists during flight. Experiments are conducted in a hypersonic wind tunnel at a nominal Mach number of 6. It is demonstrated that the shock/shock interaction on the blunt body is avoided due to injection and the peak pressure at the reattachment point is reduced by 70% under a 4A degrees attack angle.

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The rarefied gas effects on several configurations are investigated under hypersonic flow conditions using the direct simulation Mont Carlo method. It is found that the Knudsen number, the Mach number, and the angle of attack all play a mixed role in the aerodynamics of a flat plate. The ratio of lift to drag decreases as the Knudsen number increases. Studies on 3D delta wings show that the ratio of lift to drag could be increased by decreasing the wing thickness and/or by increasing the wing span. It is also found that the waveriders could produce larger ratio of lift to drag as compared with the delta wing having the same length, wing span, and cross section area.

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Intertidal macroalgae experience continual alternation of photosynthesis between aquatic state at high tide and aerial state at low tide. The comparative photosynthetic responses to inorganic carbon were investigated in the common intertidal macroalga Ulva lactuca L. along the coast of Shantou between aquatic and aerial state. The inorganic carbon dissolved in seawater at present could fully (at 10 degreesC or 20 degreesC) or nearly (at 30 degreesC) saturate the aquatic photosynthesis of U. lactuca. However, the aerial photosynthesis was limited by current ambient atmospheric CO2 level, and such a limitation was more severe at higher temperature (20degrees - 30degrees T) than at lower temperature (10 T). The carbon-saturated maximal photosynthesis of U. lactuca under aerial state was much greater than that under aquatic state at 10 degreesC and 20 degreesC, while the maximal photosynthesis under both states was similar at 30 degreesC. The aerial values of K-m (CO2) for photosynthesis were higher than the aquatic values. On the contrary, the values of apparent photosynthetic CO2 conductance under aerial state were considerably lower than that under aquatic state. It was concluded that the increase of atmospheric CO2 would enhance the primary productivity of U. lactuca through stimulating the photosynthesis under aerial state during low tide.