大口径顶置火炮输弹机动力学研究

为解决大口径顶置火炮弹药自动装填系统的关键技术问题,提出了大口径顶置火炮输弹机各工作阶段的力学模型和动力学方程,并通过输弹速度与时间的计算分析,得到了3种输弹方式的输弹速度与时间关系曲线,其结果对大口径顶置火炮供输弹系统的研究具有较大参考价值。     

Adaptive control of track tension estimation using radial basis function neural network

Track tension is a major factor influencing the reliability of a track. In order to reduce the risk of track peel-off, it is necessary to keep track tension constant. However, it is difficult to measure the dynamic tension during off-road operation. Based on the analysis of the relation and external forces depending on free body diagrams of the idler, idler arm, road wheel and road arm, a theoretical estimation model of track tension is built. Comparing estimation results with multibody dynamics simulation results, the rationality of track tension monitor is validated. By the aid of this monitor, a track tension control system is designed, which includes a self-tuning proportional-integral-derivative (PID) controller based on radial basis function neural network, an electro-hydraulic servo system and an idler arm. The tightness of track can be adjusted by turning the idler arm. Simulation results of the vehicle starting process indicate that the controller can reach different expected tensions quickly and accurately. Compared with a traditional PID controller, the proposed controller has a stronger anti-disturbance ability by amending control pa-rameters online.     

Simulation on the dynamic stability derivatives of battle-structure-damaged aircrafts

Accurately evaluating the aerodynamic performance of a battle-structure-damaged aircraft is essential to enable the pilot to optimize the flight control strategy. Based on CFD and rigid dynamic mesh techniques, a numerical method is developed to calculate the longitudinal and longitudinal-lateral coupling forces and moments with small amplitude sinusoidal pitch oscillation, and the corresponding dynamic de-rivatives of two fragment-structure-damaged and two continuous-rod-damaged models modified from the SACCON UAV. The results indicate that, at the reference point set in this paper, additional positive damping is generated in fragment-damaged configurations; thus, the absolute values of the negative pitch dynamic derivative increase. The missing wingtip induces negative pitch damping on the aircraft and decreases the value of the pitch dynamic derivative. The missing middle wing causes a noticeable increase in the absolute value of the pitch dynamic derivative;the missing parts on the right wing cause the aircraft to roll to the right side in the dynamic process, and the pitch-roll coupling cross dynamic derivatives are positive. Moreover, the values of these derivatives increase as the damaged area on the right wing increases, and an optimal case with the smallest cross dynamic derivative can be found to help improve the survivability of damaged aircraft.     

基于SD的科研项目管理动态仿真初探

为解决管理中的动态、非线性等复杂性问题,将系统动力学方法引进到科研项目管理中,依据系统动力学原理,对科研项目管理系统进行因果关系分析并建立了流图模型.实例仿真结果表明:系统动力学方法为科研项目管理的正确决策提供了科学依据.     

Boltzmann 方程求解方法综述

本文论述了Ｂｏｌｔｚｍａｎｎ方程的求解方法，在分析了各类求解方法的优缺点之后指出目前Ｍｏｎｔｅ－Ｃａｒｌｏ直接模拟方法是解决稀薄气体动力学问题的最佳方法。     

冗余并联机构的PD控制

采用并联机构的简化树动力学模型 (reducedtreemodel) ,给出了冗余并联结构的动力学方程和基于PD控制策略的控制方法。为了消除冗余并联机构固有的内作用力 ,给出了一种基于静态力平衡的控制方法。最后 ,利用一个 2自由度的冗余平面并联机构作为控制实例 ,实验结果表明了控制方法的正确性     

基于零动态设计原理的刚体姿态控制

采用四元数,古典的Rodrigues参数和修改的Rodrigues参数来描述刚体旋转运动.基于微分几何中的零动态设计原理,首先构造一个输出映射,使系统具有相对阶{1,…,1}且零动态渐近稳定.然后求出一类反馈控制器,使得系统部分线性化为一指数稳定的线性方程.仿真结果表明,所求控制器能使闭环系统稳定.     

零动态设计方法在鱼雷纵向运动控制中的应用

鱼雷纵向运动方程是非线性微分方程 ,非线性系统近似线性化建模方法有着不可忽视的局限性 .非线性系统的精确线性化设计方法由于其复杂性而限制了它的应用 .将零动态设计方法应用于鱼雷纵向系统 ,为解决鱼雷非线性控制系统稳定设计提供了新的途径 .     

遗传算法在动力学优化中的应用

根据动力学优化设计问题的特点,并利用复合形法对一般遗传算法进行了改进,在此基础上提出了一种新的动力学优化设计方法。数值分析结果表明,该方法结果正确,算法简洁。     

高超声速流动计算中LU-SGS隐式算法的应用研究

在高超声速条件下,对原始LU-SGS格式及其改进方法的收敛速度做了深入地比较分析,目的是进一步更好地将LU-SGS算法用于工程上复杂外形的计算模拟当中。二维圆柱,三维钝锥及空天飞机算例的结果表明：(i)对于高超声速粘性流动的计算,粘性项应进行隐式处理;(ii)BLU-SGS方法给出的内迭代方式的收敛性优于DP-LUR方法所给出的内迭代方式;(iii)LU-SGS算法中雅克比系数矩阵的计算方式对计算量及收敛性影响较大,若采用精确的矩阵形式则在流动无分离情况下能取得快速收敛的效果,而在含有流动分离的情况因受稳定性的影响精确的矩阵形式的收敛表现不及对角近似形式。