规则波浪对水下航行体出水姿态参数的影响

基于边界元方法建立了水下航行体出水姿态计算模型，包括各控制方程及边界条件，采用截平面方法对航行体出水模型进行了简化处理，并将所得结果和实验数据进行比对，发现二者符合良好，验证了数值模型的有效性。运用边界元法研究了规则波浪参数（波高、浪向、周期、相位）对出水姿态的影响。研究结果表明，波高影响波浪力幅值大小，对出水姿态参数有着直接的影响，波高越大对出水姿态参数的影响越大；浪向、初相位和周期主要影响流体质点的运动方向，改变波浪附加惯性力，影响波浪力对出水姿态参数的作用效果；受到出水相位的影响，出水俯仰角和俯仰角速度呈余弦变化规律；随着周期的增大，周期对航行体出水姿态参数的影响逐渐减小，此时，相同波高下出水姿态参数只受到出水相位的影响。     

基于INS/前视声纳组合的输水隧洞AUV巡检定位方法

当潜航器(AUV)进行输水隧洞巡检时,多普勒测速仪(DVL)声波会对前视声纳图像产生干扰,针对这一问题提出了一种从AUV上卸载DVL,直接从前视声纳图像中提取栽体速度,而后和惯性测量单元(IMU)进行组合导航的方法.该方法根据前视声纳成像原理,建立起每相邻两帧声纳图像间载体的相对位移与配对特征点的图像坐标之间的联系,针对水底为局部平坦区域的情况,对特征点仰角进行了估算.通过惯导速度约束和随机抽样一致(RANSAC)算法,剔除误差较大的配对点,然后利用提取出的载体速度作为观测量进行卡尔曼滤波.经实际数据测试,惯性导航系统(INS)/前视声纳组合的总体性能和INS/DVL组合非常接近,以输水隧洞内的接缝线作为定位基准,INS/前视声纳组合导航在沿隧洞方向上的最大相对定位误差小于行程的1％.     

Hardware qualification for scientific ballooning missions

The European Stratospheric Balloon Observatory (ESBO) initiative aims at simplifying the access to stratospheric balloon missions. We plan to provide platforms and support with instrument design in order to support scientists. During the design process, the inevitable question of qualification for the harsh flight conditions arises. Unfortunately, there is no existing standard for qualification of stratospheric ballooning hardware. Thus, we developed a qualification procedure for use within ESBO and similar projects.In this paper, we present our analysis of the environmental conditions in the stratosphere. While conditions at typical balloon float altitudes are similar to the space environment, there are also some relevant differences. For example, the thermal environment is dominated by radiation and thermal conduction, but the remaining atmosphere still supports a certain amount of convection. The remaining atmospheric pressure in the stratosphere also leads to reduced arcing distances. Vibrational loads are far less than for space missions, but quasi-static or shock loads may occur. The criticality of radiation increases with mission duration.Based on the environmental conditions, we present the qualification procedures for ESBO, which are based on the European Cooperation for Space Standardization (ECSS) standards for space systems. Overtesting against too high requirements leads to overengineering, driving mission cost and mitigating the advantages of balloons over space missions. Therefore, we modified the ECSS standards to fit typical scientific ballooning missions over several days at altitudes up to 40 km. Furthermore, we analyzed design rules for space systems with regard to their relevance for scientific ballooning, including material and component selection. We present the experience from the hardware qualification process for the ESBO prototype STUDIO (Stratospheric UV Demonstrator of an Imaging Observatory). Even though boundary conditions are different for each individual mission, we aimed for a broader approach: We investigated more general requirements for scientific ballooning missions to support future flights.