排序方式: 共有49条查询结果,搜索用时 31 毫秒
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基于序列二次规划算法的再入轨迹优化研究 总被引:5,自引:0,他引:5
介绍了序列二次规划算法在飞行器再入轨迹优化问题中的应用.首先引入了能量替代变量对无量纲运动方程进行推导,使得运动方程和优化问题易于处理,考虑严格的过程约束和终端约束,以攻角和倾侧角为控制变量,总加热量最小为性能指标;然后通过直接配点法将最优控制问题转化为非线性规划问题,选取各节点的状态量和控制量作为优化参数;最后应用序列二次规划算法对非线性规划问题进行求解.针对多约束的再入飞行器的轨迹优化时对初值敏感的问题,提出一种参考轨迹快速规划算法,提高了优化速度.仿真结果表明提出的方法能够较快地搜索到最优轨迹,满足所有约束且落点精度高. 相似文献
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Dynamic fault tree analysis is widely used for the reliability analysis of the complex system with dynamic failure characteristics. In many circumstances, the exact value of system reliability is difficult to obtain due to absent or insufficient data for failure probabilities or failure rates of components. The traditional fuzzy operation arithmetic based on extension principle or interval theory may lead to fuzzy accumulations. Moreover, the existing fuzzy dynamic fault tree analysis methods are restricted to the case that all system components follow exponential time-to-failure distributions. To overcome these problems, a new fuzzy dynamic fault tree analysis approach based on the weakest n-dimensional t-norm arithmetic and developed sequential binary decision diagrams method is proposed to evaluate system fuzzy reliability. Compared with the existing approach, the proposed method can effectively reduce fuzzy cumulative and be applicable to any time-to-failure distribution type for system components. Finally, a case study is presented to illustrate the application and advantages of the proposed approach. 相似文献
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To avoid the numerical complexities of the battery discharge law of electric-powered rotorcrafts,this study uses the Kriging method to model the discharge characteristics of Li-Po batteries under standard conditions.A linear current compensation term and an ambient temperature compensation term based on radial basis functions are then applied to the trained Kriging model,leading to the complete discharged capacity-terminal voltage model.Using an orthogonal experimental design and a sequential method,the coefficients of the current and ambient temperature compensation terms are determined through robust optimization.An endurance calculation model for electric-powered rotorcrafts is then established,based on the battery discharge model,through numerical integration.Laboratory tests show that the maximum relative error of the proposed discharged capacity-terminal voltage model at detection points is 0.0086,and that of the rotorcraft endurance calculation model is 0.0195,thus verifying their accuracy.A flight test further demonstrates the applicability of the proposed endurance model to general electric-powered rotorcrafts. 相似文献
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为了在设计阶段提升带直二元喷管涡扇发动机的总体性能,本文开展了基于直二元喷管形面优化的涡扇发动机参数优化的研究。首先,建立了带直二元喷管的涡扇发动机模型,提出了发动机正后向排气系统红外辐射特征的计算方法,分析了直二元喷管尺寸对发动机性能参数的影响;其次,提出了基于序列二次规划算法的设计参数多目标优化方法,优化的目标包括高单位推力、低油耗和低红外辐射强度;最后,基于以上模型,利用序列二次规划算法对在设计点非加力情况下的涡扇发动机设计参数进行多目标优化。仿真结果表明:在设计点上,相较于不带直二元喷管的涡扇发动机,带直二元喷管的涡扇发动机具有更好的红外性能,并且通过算法优化后,带直二元喷管的涡扇发动机具有更好的性能参数。 相似文献
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在给定截尾试验次数的条件下,为了在理论上给出最大截尾试验次数以及从保护使用方利益的原则出发进行试验设计,基于验后概率和"小概率事件原理",在一定程度上以保护使用方利益为准则,对Bayesian序贯方差检验(BSVT)模型进行了修正,建立了修正的Bayesian序贯方差检验(MBSVT)模型,设计了继续试验区临界值的求解... 相似文献
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针对无人机系统可靠性的统计特性,分析了二项分布系统和分布单元可靠性参数评估方法,并成功应用到某型无人机系统可靠性测试中。该方法对其他类型的装备可靠性评估具有一定借鉴意义。 相似文献
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针对月面着陆器动力下降制导过程中,时变惯性加速度和重力加速度难以估计与补偿等问题,提出一种基于序列凸优化的在线制导算法。在考虑月面曲率及月球自转的着陆器动力学建模基础上,首先对模型及约束条件进行凸化,得到一个二阶锥规划(SOCP)问题;然后对经典序列凸优化进行了改进,对时变加速度剖面予以实时估计和补偿,提升了现有优化算法的性能,使着陆器在尽可能节约燃料的前提下实现高精度着陆。仿真结果表明,与经典的显式制导律相比,所提出的算法在动力下降段燃料消耗更少。由多种位置偏差下的打靶分析结果可知,所提出的算法均能满足性能指标要求;即使起始位置存在±2500 m的较大波动时,仍能以高精度的速度、位置完成动力下降制导。 相似文献