基于模糊控制的水下自航行器着陆策略分析

由于所携带能源总量的限制,目前水下自航行器(Autonomous underwater vehicle,AUV)不能满足长时间海洋环境测量的要求.为了有效地减少能耗,解决AUV工作时间短的问题,提出一种具有变浮力系统、能够着陆坐底的小型AUV.该AUV通过着陆坐底实现定点测量,可以利用有限的能源实现长时间的海洋环境监测.基于此,对AUV的着陆策略进行研究.在对注水自由下沉着陆策略进行分析的基础上,分析水舱注水量与着陆速度、着陆时间以及着陆俯仰角的关系.最终选择控制注水着陆策略作为AUV的水下着陆方案,并基于模糊控制设计着陆控制器.该方法根据AUV距离海底的高度和俯仰角通过模糊推理来控制AUV水舱的注水量,可以使AUV以较短的时间着陆于海底,同时又将着陆速度和着陆俯仰角控制在很小的范围内,满足了AUV安全着陆的要求.仿真和水域试验结果证明了采用该着陆策略的可行性.     

基于零力矩点理论的腿式着陆器着陆稳定性研究

为得出腿式着陆器着陆稳定性判据及提高其着陆稳定性的方法,给出腿式着陆器的结构原理,结合腿式着陆器的结构特点,基于零力矩点(Zero moment point,ZMP)理论研究腿式着陆器着陆过程的稳定性及其相关理论,给出基于ZMP的腿式着陆器着陆稳定性分析流程,为腿式着陆器着陆稳定性研究提供参考。为验证所提出基于零力矩点理论的腿式着陆器着陆稳定性研究方法的正确性,以哈尔滨工业大学研制的四腿桁架式月球着陆器样机为例,结合所提出的腿式着陆器着陆稳定性研究方法,给出四腿桁架式月球着陆器样机的支撑多边形与ZMP的关系图,并得到了该样机在着陆过程中的ZMP及支撑多边形的计算公式,最后给出通过判断着陆器的ZMP是否位于其支撑多边形内部来判断腿式着陆器是否稳定的方法。     

欠驱动AUV水平面轨迹跟踪的反步控制研究

针对欠驱动AUV水平面轨迹跟踪响应速度慢、系统抖振严重、运动轨迹与期望轨迹误差大的问题,对AUV经典的运动形式即水平面轨迹跟踪的运动特点进行了研究,分析了AUV水平面的运动规律。通过将地面误差变量转换为船体坐标变量的方法,建立了AUV水平面的误差方程,基于反步控制算法设计了欠驱动AUV水平面轨迹跟踪反步控制器,利用Lyapunov稳定性理论分析了整个闭环控制系统的稳定性。通过Matlab软件的数值仿真对所设计的控制器的有效性进行了验证。同时,利用设计的反步控制器在无外界干扰条件下对AUV轨迹跟踪进行了仿真,用以验证轨迹跟踪算法的稳定性。实验结果表明:AUV的运动控制轨迹能够与期望曲线重合,水平面运动轨迹的误差在可控范围,并且各个指标都趋于稳定。     

基于Lyapunov指数法的四旋翼飞行器运动稳定性分析

针对"四旋翼飞行器在相对复杂的近地空间,容易受到气流扰动,而出现抖动和失控等运动稳定性"问题。采用Lyapunov指数法对四旋翼飞行器运动稳定性开展研究:首先,利用欧拉-庞卡莱方程建立此飞行器的动力学模型,进而分析得到系统结构参数与稳定性之间的量化关系;其次,利用Lyapunov指数分析法进行稳定性分析。先进行Lyapunov指数计算,并对影响Lyapunov指数的主要参数进行分析,计算飞行器在起飞和着陆阶段对应姿态的Lyapunov指数谱,结果得到起飞阶段的稳定性比着陆阶段的稳定性好。最后,针对四旋翼飞行器在着陆阶段稳定性较差的情况,通过改变旋翼与机体中心距L的数值,可以提高其运动稳定性能。     

测量型深水AUV垂直面运动稳定性设计

测量型自主水下航行器(AUV)垂直面运动稳定性对于其顺利完成长时间深海作业、保证航行效率和安全性至关重要。以天津大学研制的用于海底地形地貌测量的深水AUV为应用对象,根据古尔维茨判别法推导了其垂直面运动稳定性衡准表达式,通过数值模拟水池试验获得了稳定性衡准判别式所需的水动力导数,分析了不同水动力外形因素(主体外形和尾翼布局形式)对其运动稳定性的影响。结果表明,具有较大纵中剖面投影面积的水动力外形的AUV,以及拥有X尾翼布局的AUV具有更好的垂直面运动稳定性。     

垂直降落运载器着陆动力学建模与稳定性分析

目前,垂直起降运载器的可重复使用是大量节约空间进入成本的直接有效方式。如若运载器在整个着陆过程中维持未倾翻状态直至安全着陆,则意味着实现了运载器的成功回收。在垂直起降可重复使用运载器着陆过程中,利用着陆装置吸收冲击能量以协助运载器实现稳定是其最终环节,此过程对运载器能否安全着陆有重要影响。针对支腿式运载器着陆装置,在传统多体动力学分析基础上,引入含摩擦单点碰撞模型以模拟足地碰撞引起的动力学不连续过程,建立典型着陆模式下运载器各着陆状态动力学方程,构建腿式着陆装置运载器完整着陆过程有限状态机。通过数值仿真计算,对运载器着陆结果进行参数化区间划分,获得稳定着陆的参数组合,可为后续运载器着陆控制提供策略参考和技术支撑。     

AUV模块化建模的一种方法

针对AUV(自主式水下航行器)的建模提出了一种新的方法.该方法对组成AUV的各个部分进行的模块化建模,当AUV在改变或更换一些部件配置以满足不同的任务需求时,只需对更改模块进行必要的计算,其他未变动的模块数据可以重复使用,从而快速方便的得到新模型.该方法的准确性通过仿真结果与其他已知模型进行比较验证.     

涵道式无人飞行器的动力学建模与运动稳定性分析

涵道式无人飞行器在起飞/着陆过程中,由于近地空间复杂气流等扰动的作用,极易产生钟摆振动、精度降低、失控坠落等运动失稳现象。针对求解动力学方程或Lyapunov直接法分析系统运动稳定性存在着方程难以求解及Lyapunov函数难以构建等问题,通过Lyapunov指数方法建立了飞行器结构参数与系统运动稳定性之间的量化关系,为指导系统的机械结构设计及控制系统优化,提高其系统的可靠性和稳定性提供参考。该方法与Lyapunov直接法相比,具有可构建性、计算过程简单等特点。     

AUV轻外壳形体选型研究

轻外壳形体研究是水下自治式航行器(AUV)结构设计的一个主要方面,出于各自的原因如功能需要、容纳空间等,轻外壳形体结构形式多种多样。介绍了AUV轻外壳形体选型研究现状及考虑的主要因素,通过对Odyssey系列产品的分析,提出了一种能悬停的小型珊瑚鱼型水下自治式航行器(AUV)。     

无人自治水下航行器外形及推进系统优化设计

无人自治水下航行器(AUV)的航程直接影响了其执行水下调查任务的能力,提高航程的关键在于减小其外形阻力及提高推进系统效率。根据航行器Myring外形的曲线方程及阻力求解公式,通过程序编写对不同外形参数下AUV的阻力进行迭代求解,获得了优化的低阻力外形;并根据AUV周围的流场结构,利用升力线理论设计了适用于无人自治水下航行器的高效率螺旋桨叶型。最后提出与螺旋桨相匹配电机的选择方案,以保证整个推进系统的效率最优。通过理论分析计算与工程实践相结合的方式,为中、小型大航程Myring外形AUV的阻力预报、艇型及推进系统设计提供了参考。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Fifth International Summer School on Screw-Theory Based Methods in Robotics

正3-11 September,2014University of Bologna,Bologna,Italy www.summerscrews.org summerscrews2014.ing.unibo.it SUMMER 20SCREWS 14In 2014,our screw-theory school comes to the world's oldest university.In early September,Summer Screws'14 will gather six experts in the application of screw theory in robotics and up to 40 participants at the University of Bologna,Bologna,Italy.The school will teach attendees how to apply existing methods and empower them to develop new ones in their own research.The basic theoretical notions will be introduced in a rigorous manner,emphasizing examples,applications,and exercises.Scholarships are available.     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

INDUSTRIAL ENGINEERING AND VISUALISATION-A PRODUCT DEVELOPMENT PERSPECTIVE

Taking the actual project of teaching and researching process for example, the relationship between the industrial engineering and product development is discussed. And use the novel visualization technology to support the industrial engineering and product development. How to use the new computer modeling and simulating technologies to support the product development and industrial engineering, is introduced especially. The support includes both domestic products and industrial systems. The visualization and computer technologies take a very important role in some system or multi-direction modeling, those technologies mentioned above can help the industrial engineers study the effect of design on the whole life circle, including the producing steps. So the engineers can avoid making the wrong decision which may cause bad effects on the whole industrial engineering.