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yoyo运动的实时轨迹生成

计算机工程与应用 2010年第10期46卷 23-27页

作者：袁德虎金惠良上海交通大学机械与动力工程学院SMC技术中心上海200240 上海航天控制工程研究所上海200233

基于NTG(Nonlinear Trajectory Generation)软件包提出了一种机器人yoyo运动实时最优轨迹生成的通用方法,即数值解法,该方法也可以应用于其他类似周期性动态系统的轨迹规划问题。对于这类系统的实时最优控制来说,一个最为关键的问题就... 详细信息

基于NTG(Nonlinear Trajectory Generation)软件包提出了一种机器人yoyo运动实时最优轨迹生成的通用方法,即数值解法,该方法也可以应用于其他类似周期性动态系统的轨迹规划问题。对于这类系统的实时最优控制来说,一个最为关键的问题就是如何实现快速求解最优轨迹,以满足实时性要求。而传统的数值求解方法都很费时。通过把最优问题映射一个较低维的空间进行求解,并且利用多线程编程技术,大大减少了计算所用的时间。仿真结果显示所求得的数值解与解析解完全相同,这也验证了该方法的正确性。单循环yoyo仿真的计算时间为10ms左右,这表明该方法完全可以应用于实时控制。

关键词： yoyo运动最优控制实时轨迹生成

基于遗传算法的挠性航天器大角度机动的变结构控制

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上海航天 2005年第1期22卷 15-18页

作者：周连文周军李卫华西北工业大学航天学院

为改善带挠性梁航天器大角度机动的变结构控制精度,在建立挠性系统动力学模型的基础上,基于喷气飞轮执行机构工作模式,设计了简单易行的滑模变结构控制策略,并采用遗传算法(GA)优化了滑动平面和边界层厚度。仿真结果表明,优化后的控制... 详细信息

为改善带挠性梁航天器大角度机动的变结构控制精度,在建立挠性系统动力学模型的基础上,基于喷气飞轮执行机构工作模式,设计了简单易行的滑模变结构控制策略,并采用遗传算法(GA)优化了滑动平面和边界层厚度。仿真结果表明,优化后的控制器能对航天器的大角度机动进行有效控制。

关键词：挠性航天器大角度机动变结构控制遗传算法振动抑制

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充液航天器液体晃动等效力学模型的建立

上海航天 2003年第4期20卷 1-5页

作者：李英波冯正进上海航天控制工程研究所上海200233 上海交通大学上海200030

在考虑液体表面张力影响液体晃动求解的基础上 ,利用动力学方程等价准则 ,建立了三轴定向充液卫星在二维平动和二维摆动扰动作用下的空间摆等效力学模型 ,并对两种情况下等效摆的主要参数进行了计算和比较。结果表明 ,考虑表面张力时。

关键词：液体晃动等效力学模型液体表面张力航天器空间摆

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卫星惯性姿态敏感器技术

上海航天 2003年第5期20卷 33-37页

作者：刘付成刘汝滨国防科技大学航天与材料工程学院湖南长沙410073 上海航天控制工程研究所上海200233

介绍了卫星惯性姿态敏感器(IAS)的工作原理,分析了惯性姿态敏感器设计及关键技术。通过比较各种惯性姿态敏感器的优缺点,分析了卫星惯性姿态敏感器的发展历程,探讨了卫星用惯性姿态敏感器的发展方向。

关键词：卫星惯性姿态敏感器惯性测量装置液浮陀螺工作原理

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基于GPS的低轨伴飞卫星自主导航轨道确定

上海航天 2010年第2期27卷 38-45页

作者：杨文博李英波施常勇周曜上海航天控制工程研究所上海200233 中智上海经济技术合作公司上海200030

对基于EKF算法的相对导航滤波器和基于全球卫星定位系统(GPS)伪距测量的伴飞星定轨进行了研究。用几何法与相对动力学方法联合获得目标星轨道信息,给出了伴飞卫星伪距测量定位的模型。仿真结果表明:该定轨方法可用于低轨卫星实时定位导... 详细信息

对基于EKF算法的相对导航滤波器和基于全球卫星定位系统(GPS)伪距测量的伴飞星定轨进行了研究。用几何法与相对动力学方法联合获得目标星轨道信息,给出了伴飞卫星伪距测量定位的模型。仿真结果表明:该定轨方法可用于低轨卫星实时定位导航,定轨精度较高。

关键词：伴飞星自主导航全球卫星定位系统扩展Kalman滤波伪距定轨

Response of Cytoskeleton of Murine Osteoblast Cultures to Two-step Freezing

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Acta Biochimica et Biophysica Sinica 2005年第12期37卷 814-818页

作者： Bao-Lin LIU~1 John McGRATH~21 institute of Cryobiology,University of shanghai for Science and Technology,shanghai 200093,china 2 Department of aerospace and Mechanical engineering,University of Ariona,Tucson 85721,USA institute of Cryobiology University of Shanghai for Science and TechnologyShanghai 200093 China Department of aerospace and Mechanical engineering University of ArizonaTucson 85721 USA

Understanding the ultrastructural response of cells to the freezing process is important fordesigning cryopreservation strategies for cells and *** cellular structures of attached cells are targetsof cryopreservation-induced *** fluorescence staining was used to assess the status of theactin filaments (F-actin) of murine osteoblasts attached to hydroxyapatite discs and plastic coverslips for atwo-step freezing *** F-actin of dead cells was depolymerized and distorted in the freezing *** that of live cells had little *** results suggest that the cytoskeleton may support the robustnessof cells during *** present study helps to investigate the damage mechanism of attachedcells during the freezing process.

关键词： cytoskeleton osteoblast actin filament two-step freezing

Study of control effects of vortex generators on a supercritical wing

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Science china(Technological Sciences) 2010年第8期53卷 2038-2048页

作者： HUANG JingBo 1 ,XIAO ZhiXiang 1 ,FU Song 1 &ZHANG Miao 2 1 School of aerospace engineering,Tsinghua University,Beijing 100084,china 2 shanghai Aircraft Design and Research institute of COMAC,shanghai 200232,china School of aerospace engineering Tsinghua University shanghai Aircraft Design and Research institute of COMAC

Flows around vortex generators(VGs),which serve as one of the important flow control methods,are investigated by solving Reynolds-averaged Navier-Stokes(RANS)*** influences on the main flow of VGs are intended to ***, the flow around a single VG on a flat plane is computed to validate the schemes and to acquire basic knowledge of this kind of ***,transonic flow past a standard model,named by ONERA-M6 wing,is predicted to investigate the flow features of shockwave/boundary-layer interactions(SWBLI).Thirdly,the effects of a row of VGs mounted about 25%local chord on a supercritical wing are analyzed in transonic condition with strong ***,VGs are mounted more upwind(about 3.5%local chord)to explore the effects at low speed and high incidence *** numerical results show that seven VGs can effectively suppress the separations behind the strong SWBLI and decrease spanwise flow and wing-tip vortex in transonic *** also can decrease the large scope of separation over the wing at low speed with high angle of attack.

关键词： supercritical wing vortex generator(VG) shockwave/boundary-layer interactions(SWBLI)

Time-varying sliding mode control for a class of uncertain MIMO nonlinear system subject to control input constraint

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Science china(Information Sciences) 2010年第1期53卷 89-100页

作者： JIN YongQiang1,2, LIU XiangDong1, QIU Wei2 & HOU ChaoZhen1 1Department of Automatic control, Beijing institute of Technology, Beijing 100081, china 2aerospace System engineering shanghai, shanghai 201108, china Department of Automatic control Beijing Institute of Technology Beijing China aerospace System engineering shanghai Shanghai China

To solve the regulator problem of a class of uncertain MIMO nonlinear systems subject to control input constraint, three types of time-varying sliding mode control laws are proposed. The sliding surfaces pass the initial value of the system at the initial time, and are shifted/rotated towards the predetermined ones. The controller parameters are optimized by genetic algorithm (GA). Lyapunov method is adopted to prove the stability and robustness to the parameter uncertainties and external disturbance. By mean of time-varying sliding mode control law, the reaching phase in the conventional sliding mode control is eliminated, and the system is guaranteed to have robustness from the very beginning. Taking the control of two-link manipulator and attitude tracking of rigid spacecraft as two examples, we illustrate the features of the time-varying sliding mode control. The simulation results show the validity of the control law to a class of uncertain MIMO systems. Better robustness against the uncertainties and external disturbance could be achieved by time-varying sliding mode control without violating the constraint on control input.

关键词： time-varying sliding surface sliding mode control MIMO nonlinear system uncertain control input constraints

Nonlinear constitutive law for ferroelectric/ferroelastic material and its finite element realization

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Science china(Physics,Mechanics & Astronomy) 2007年第1期50卷 70-86页

作者： LI YaoChen Department of aerospace engineering and Applied Mechanics,Tongji University,shanghai 200092,china Department of aerospace engineering and Applied Mechanics Tongji University Shanghai 200092 China

The hysteresis phenomena of ferroelectric/ferroelastic material in polarization procedure are investigated. Some assumptions are presented based on the published experimental data. The electrical yielding criterion, mechanical yielding criterion and isotropic hardening model are established. The flow theory in incremental forms in polarization procedure is presented. The nonlinear constitutive law for electrical-mechanical coupling is proposed phenomenologically. Finally, the nonlinear constitutive law expressed in a form of matrices and vectors, which is immediately associated with finite element analysis, is formulated. In the example problem of a rectangular specimen subjected to a uniaxial electric field, the procedure from virgin state to fully polarized state is simulated. Afterward, a uniaxial compressive loading is applied to depolarizing the specimen. Results are in agreement with the experimental data.

关键词： ferroelectric/ferroelastic material constitutive law nonlinear finite element method.