基于运动轨迹分量的行人徘徊行为检测研究

针对传统的目标徘徊检测方法在实时性和准确性等方面的不足,本文提出了一种基于目标轨迹分量曲线的行人徘徊检测算法。首先采用帧差法的背景模板建模方法来建立初始背景。然后用改进的结合背景差分的三帧差分法检测前景目标,通过Mean-shift算法对前景目标进行跟踪。最后将得到的运动轨迹做正交分解,根据根据轨迹的X,Y轴分量曲线来对徘徊行为进行识别。实验表明,该方法能够对几种典型的徘徊行为进行实时、精确判断,同时可以检测出其他复杂的徘徊行为,有较好的实时性和准确率。     

The Aurora Project

The new opportunities for simulation and representation that computer modelling affords designers has been well charted. Jason Kelly Johnson and Nataly Gattegno of Future Cities Lab, however, are combining these new potentials with dynamic mapping and modelling methods derived from modern cartography. The most familiar of these tools is Google Earth, which provides a unique new bird's-eye view of the earth's surface. Other geographical softwares also combine to enable the manipulation of real-time, open-source, user-generated data as never before. Copyright © 2010 John Wiley & Sons, Ltd.     

桨叶附着涡环量分布的迭代算法

结合升力线理论和叶素理论给出了一种桨叶附着涡环量分布的迭代算法，并用此算法计算了悬停状态下模型旋翼桨叶的附着涡环量分布，计算结果与实验数据吻合较好，且收敛较快，证明了该方法的有效性。     

悬停回转试飞方法在直升机超短波天线方向图测试中的应用

借鉴飞机天线方向图地面自由空间测试场测试方法,利用直升机空中悬停特性进行天线方向图测试,以达到节省试飞架次的目的.分析了如何进行直升机悬停位置的选择以及直升机到测试点的距离和垂直高度的计算,总结了直升机超短波天线方向图测试中的定点悬停试飞驾驶技术.该试验方法在飞行试验中得到了验证,与传统试飞方法进行对比,工作效率提高2倍.     

Thruster fault-tolerant control of a hovering AUV with four horizontal and two vertical thrusters

This paper deals with the motion control of a hovering autonomous underwater vehicle (AUV) with four horizontal and two vertical thrusters, when one or more thrusters are completely malfunctioned. Three thruster fault cases are considered: one horizontal thruster is faulty; two horizontal thrusters are faulty; and one vertical thruster is faulty. Through a series of simulations and an experiment, it is validated that the AUV can track a planned path in a 3-D space with minimally three thrusters (two are horizontal ones); however, some cases require the changes of the vehicle’s preferred direction of motion and its movement manner. Additionally, when the number of active horizontal thrusters is less than the required degree-of-freedom, a continuous state feedback control law does not exist due to the non-holonomic constraint. This paper highlights that the hovering AUV can overcome the non-holonomic constraint if using the feature that their translational and rotational motions can be controlled independently.     

基于金字塔光流法的无人机室内定点悬停设计

针对GPS定位系统建筑物内信号弱,小型无人机很难在室内实现定点悬停.本文提出了一种利用计算机视觉融合惯性导航的组合控制方案.在光流估计上,采用金字塔LK光流算法,提高特征点跟踪精度.在速度融合上,采用卡尔曼+互补混合融合方案,提高飞行速度的准确性.在飞行控制上,采用高度、姿态串级闭环控制方案,光流作为姿态估计的补偿值,...     

基于LQR的直升机悬停控制律设计与仿真

建立了某型直升机数学模型,并将该模型分解为纵向模型和横侧向模型两部分,提出了悬停控制律应该达到的稳态指标;以该型直升机为被控对象,采用输出反馈线性二次型调节器(LQR)技术设计了由纵向控制律和横侧向控制律组成的悬停控制律,使得直升机能取得满意的悬停性能指标;以该型直升机模型、执行器模型以及设计的悬停控制器构成全数字闭环仿真系统进行控制律仿真验证;仿真结果表明,文中设计的悬停控制律正确有效,能够较好地实现直升机的悬停功能,另外,由于该悬停控制律是基于输出反馈的,在工程上也比较容易实现。     

Development of hovering control system for an underwater vehicle to perform core internal inspections

In this paper, a hovering control system for an underwater vehicle is proposed to support core internal inspections. The system adopted a localization part and a thruster control part. The former utilizes a map-matching method, referring cross-sectional shape data cut from a three-dimensional computer aided design (CAD) and structural shapes measured by a laser range system for horizontal positioning. A pressure sensor provides vertical positioning. The latter utilizes the thrust vector control, or reference thrust vectors are converted to each propeller thrust based on the vehicle's geometric structure. Experiments to evaluate performance of the proposed system were implemented at a mock-up of the reactor bottom part. As a result, it was confirmed that the position was detected with an accuracy of 48 mm, and for a flow velocity of 200 mm/s, it was verified that the vehicle hovered within 77 mm of a target point. Therefore, core internal inspections can be stably carried out even where there is external force caused by water convection flow.     

空间相对悬停轨道闭环控制方法研究

空间相对悬停轨道在空间操作中具有重要的作用。提出了一种相对圆轨道目标星任意位置的悬停闭环控制方法,并基于李雅普诺夫方法设计了反馈系数,解决了由于Hill方程线性化误差导致开环控制难以保持悬停效果的问题。实验结果表明,在服务星上增施加少量的额外燃料,可以实现服务星相对目标星长时间、高精度、稳定的悬停,并通过数值仿真验证了该方法的有效性。     

旋翼模型悬停状态桨尖涡特性

直升机旋翼桨尖涡特性研究是直升机旋翼气动特性研究的关键要素,为提高对旋翼悬停状态桨尖涡特性的认识以及准确掌握其流动机理,利用Bo-105旋翼模型在Φ5 m立式风洞开口试验段进行了桨尖马赫数相似情况下的悬停试验,并采用TR-PIV流场测量系统对旋翼悬停状态下不同总距时的流场进行了精细化测量,得到了该副旋翼32帧/圈的详细流场图像,并运用更为合理的涡核中心判定、涡核流动数据提取以及涡核模型拟合方法对试验结果进行了精细化处理与分析,进一步揭示了旋翼模型悬停状态下桨尖涡的演化发展过程.研究表明:高速PIV设备能准确捕捉旋翼悬停状态下的流场运动特征,有助于旋翼流场的精细化研究;采用涡量加权平均的方法来计算涡核中心位置可以消除涡核中心平移速度的影响,进而更加准确地定位涡核中心;采用环量分析的方法可以更加可靠地确定涡核尺寸和最大诱导速度,且分析结果显示随涡龄角的增加,涡核半径缓慢增大、涡核最大诱导速度缓慢减小;在桨尖涡发展演化过程中,不同发展阶段具有不同的涡核模型n参数.