H型倾转推进两栖机器人水下姿态自抗扰控制

针对水陆两栖机器人推力不稳和环境扰动造成的姿态不稳定问题,设计了一种新型的将轮驱动与喷水推进进行复合的可倾转复合推进装置。将该可倾转复合推进装置应用在H构型两栖机器人中,基于推力倾转角分离控制策略和自抗扰控制原理设计了姿态自稳定控制器,并在耦合自由度上采用异步调节机制。使用Simulink/ADAMS联合仿真平台进行姿态稳定仿真验证,并确定了具有较好效果的控制器参数;物理样机运行实验表明,H型两栖机器人可以完成预设运动,姿态自稳定控制器能够将该机器人水下运行时的姿态抖动抑制在5°以内。     

机器鱼在线功率检测系统设计与实现

水下仿生机器鱼由于其高效而灵活的水下运动而受到广泛关注.至今,人们对于水下机器人的研究主要集中在运动仿生以及动力学机理解释等方面,对于机器鱼的运动中的实时功率消耗研究还几乎空白.其中一个主要原因是水下机器人的功率消耗不能直接实时获得,因而提出了一个实时在线高速功率测量系统,通过该系统能够实现5000S/s的采样速率,获得精确的机器鱼在水中运动下的实时功率,从而为后期提高机器鱼游动效率的研究做基础铺垫.一系列实验证明了其对水下机器人的实时效率检测的有效性.此外,实现对机器鱼的功耗评估能够更好地为设计节能型水下航行器提供有力的指南.     

A New Control Strategy of 5-Phase PM Motor under Open-Circuited Phase Based on High Order Sliding Mode and Current References Real-Time Generation

The high quality of electrical power in high power and high reliability applications is a crucial necessity even under fault mode function. However, in these conditions, the quality of the torque is a key feature. To overcome this problem, the multiphase permanent magnet (PM) motors seems to be a very attractive choice. In order to highlight the robustness and reliability of this technology, this paper investigates the control of a five-phase PM motor under an open circuited phase fault conditions. Moreover, a High Order Sliding Mode (HOSM) controller combined to an optimal reference current generation is tested and compared to a PID controller under fault mode conditions. This original control strategy is proposed for faulted conditions. Compared to classical fault tolerant control, this strategy allows a better dynamic tracking of the non-sinusoidal reference currents and leads to a smooth torque with minimal losses even in severe fault conditions. To validate the proposed control strategy, simulation, and experimental results are presented and discussed.     

跨音压气机转子多目标气动优化设计

采用基于雷诺平均N-S方程的全三维流场模拟程序和基于多目标遗传算法的数值优化程序,对跨音压气机转子NASA Rotor37进行了优化设计。对所开发的三维N-S方程求解程序进行了实验验证,完善了多目标遗传算法与响应面方法相结合的具有全局寻优能力的优化程序,以总压比和绝热效率最大为设计目标,应用该优化方法对NASA Rotor37进行考虑中弧线和厚度分布的多目标气动优化设计。结果表明:在满足流量约束的条件下,绝热效率提高了0.7%,总压比提高了0.66%,并且优化设计时间大幅减小。     

船舶电力推进系统稳定性分析

为获得变频驱动感应电机调速系统低频振荡产生的原因,以实验室一套船舶电力推进系统为例展开研究。建立了基于小扰动的感应电机、变频器及船舶电力推进系统的数学模型,分析了死区时间对系统稳定性的影响。利用根轨迹分析方法,通过解析计算与仿真分析绘制了系统的不稳定区域。讨论了电机定子电阻和漏感变化对系统稳定区域的影响,进行了试验验证,试验结果与解析计算得到的不稳定区域吻合较好,证明所建立的船舶电力推进系统小扰动数学模型以及采用的系统稳定性分析方法是正确可行的。     

基于虚拟力法的盾构隧道施工扰动地层附加应力分析

目前针对盾构隧道掘进引起周围地层附加应力的研究较少,且既有成果一般均假定施工场地为均质土体。基于层状地基基本解,结合虚拟力法,建立了考虑分层效应的盾构隧道施工扰动地层附加应力的分析方法,重点研究了盾构施工正面附加推力、盾构与土体间掘进摩擦力引起的地层附加应力。结合上海典型分层地基工程实例,分析了盾构施工引起的附加应力分布规律,且与均质土体工况下的计算结果进行了对比研究,考察了地基分层效应对扰动地层应力场的影响。计算结果表明：盾构与土体间掘进摩擦力与正面附加推力引起的土体附加应力分布规律较为相似,靠近开挖面时附加应力衰减较快且影响范围一般较小,而远离开挖面时应力衰减明显变慢,在实际工程中要重视掘进摩擦力和正面附加推力造成的施工风险;此外,考虑分层效应与常规不考虑分层效应时的附加应力场有较大差别,在设计中应重视地基非均质性带来的影响。成果可为合理制定层状地基中盾构隧道施工对临近管道以及建筑物的保护措施提供一定的理论依据。     

Self‐Propelled Activated Carbon Janus Micromotors for Efficient Water Purification

Self‐propelled activated carbon‐based Janus particle micromotors that display efficient locomotion in environmental matrices and offer effective ‘on‐the‐fly’ removal of wide range of organic and inorganic pollutants are described. The new bubble‐propelled activated carbon Janus micromotors rely on the asymmetric deposition of a catalytic Pt patch on the surface of activated carbon microspheres. The rough surface of the activated carbon microsphere substrate results in a microporous Pt structure to provide a highly catalytic layer, which leads to an effective bubble evolution and propulsion at remarkable speeds of over 500 μm/s. Such coupling of the high adsorption capacity of carbon nanoadsorbents with the rapid movement of these catalytic Janus micromotors, along with the corresponding fluid dynamics and mixing, results in a highly efficient moving adsorption platform and a greatly accelerated water purification. The adsorption kinetics and adsorption isotherms have been investigated. The remarkable decontamination efficiency of self‐propelled activated carbon‐based Janus micromotors is illustrated towards the rapid removal of heavy metals, nitroaromatic explosives, organophosphorous nerve agents and azo‐dye compounds, indicating considerable promise for diverse environmental, defense, and public health applications.     

Magnetically Modulated Pot‐Like MnFe2O4 Micromotors: Nanoparticle Assembly Fabrication and their Capability for Direct Oil Removal

This work demonstrates a simple‐structured, low‐cost magnetically modulated micromotor of MnFe₂O₄ pot‐like hollow microparticles as well as its facile, versatile, and large‐scale growing‐bubble‐templated nanoparticle (NP) assembly fabrication approach. In this approach, the hydrophobic MnFe₂O₄@oleic acid NPs in an oil droplet of chloroform and hexane assembled into a dense NP shell layer due to the hydrophobic interactions between the NP surfaces. With the encapsulated oil continuously vaporizing into high‐pressured gas bubbles, the dense MnFe₂O₄ NP shell layer then bursts, forming an asymmetric pot‐like MnFe₂O₄ micromotor by creating a single hole in it. For the as‐developed simple pot‐like MnFe₂O₄ micromotor, the catalytically generated O₂ molecules nucleate and grow into bubbles preferentially on the inner concave surface rather than on the outer convex surface, resulting in continuous ejection of O₂ bubbles from the open hole to propel it. Dexterously integrating the high catalytic activity for H₂O₂ decomposition to produce O₂ bubbles, excellent magnetic property with the instinctive surface hydrophobicity, the MnFe₂O₄ pot‐like micromotor not only can autonomously move in water media with both velocity and direction modulated by external magnetic field but also can directly serve for environmental oil removal without any further surface modification. The results here may inspire novel practical micromotors.