Load distribution strategy for multi-lift system with helicopters based on power consumption and robust adaptive game control

It is of great significance to reasonably distribute the slung load to each helicopter while considering difference in power consumption, relative position and interaction comprehensively. Therefore, the load distribution strategy based on power consumption and robust adaptive game control is proposed in this paper. The study is on a “2-lead” multi-lift system of four tandem helicopters carrying a load cooperatively. First, based on the hierarchical control, the load distribution problem is divided into two parts: the calculation of expected cable force and the calculation of the anti-disturbance cable force. Then, aimed at minimizing the maximum equivalent power of helicopter, an optimization problem is set up to calculate the expected cable force. Specially, the agent power model is trained by BP neural network, the safe distance constraint between helicopters is set to 2.5 rotor diameters to reduce aerodynamic interference, and the helicopters with different performance can be considered by introducing the equivalent power factor into the objective function. Next, considering the difference and interaction between helicopters, the robust adaptive differential game control is proposed to calculate the anti-disturbance cable force. Particularly, to solve the coupled Hamiltonian equations, an adaptive solving method for value function is proposed, and its stability is proved in the sense of Lyapunov. The simulation results indicate that the proposed load distribution method based on power consumption is applicable to the entire flight trajectory even there are differences between helicopters. The game control can consider interaction between helicopters, can deal with different objective functions, and has strong robustness and small steady-state error. Based on the entire strategy, the cable force can be reasonably allocated so as to resist disturbance and improve the flight performance of the whole system.     

基于二阶滑模的永磁同步电机SVMDTC

针对永磁同步电机空间矢量直接转矩控制中存在的磁链脉动大、转速超调大和转速动态响应速度慢等问题,提出基于Supertwisting二阶滑模控制理论将转速环、磁链环和转矩上的控制器全部换成Supertwisting滑模控制器。对所提出的控制理论利用MATLAB/Simulink仿真软件进行仿真验证。仿真结果表明所提出的控制理论能够成功抑制转速超调,实现提高转速、磁链和转矩的动态响应速度、抑制转矩和磁链脉动。     

基于力矩比优化的航天员舱外活动仿真

提出了一种基于力矩比优化的航天员人体运动控制算法,该算法综合考虑了反向运动学、反向动力学以及人体工效学等因素,避免了单纯从动力学方面求解所带来的虚拟人体动画所隐含的力量冲突,提高了仿真结果的真实性和合理性。研究结果可为航天员舱外活动的设计和考察提供一定的理论指导和技术支持。     

带褶皱的等张力体航天服软关节设计与实验

面向未来行星表面探测任务,航天服的活动性能需要进一步提高。为此,应改进航天服软关节的结构形式。根据等张力体形状内部承压时不存在周向应力的理论,在该曲面周向上加入褶片结构,设计出了带褶皱的等张力体关节,使之能够沿周向弯曲或伸展。为验证关节性能,利用柔性单自由度关节测量设备,进行了多次加卸载和不同运动范围的力矩特性研究,分析了关节的几何形态、等容性以及主应力状态,并将该关节与无褶皱的等张力体关节和平褶式关节进行了比较,最后讨论了关节的优化方向。结果表明,在测试的0°~80°范围内,关节力矩较小,最大容积变化为1.6%。关节弯曲时,等张力体曲面上周向应力仍可忽略不计。首次加载与之后的加载有一定的差异,而不同的运动范围对关节活动性能无影响。与其他两种关节形式比较,带褶皱等张力体关节在几何尺寸、运动形态和活动性能上都具有一定的优势。此外,该关节可在结构和材料方面进一步优化。     

卫星490N发动机安装位置优化研究

针对490N发动机推力在卫星变轨过程中不能始终通过卫星质心,由此形成额外力矩对卫星姿态控制造成干扰的问题,文章提出了一种根据发动机推力偏斜和卫星质心位置变化情况,优化发动机安装位置的方法。此方法通过平移和旋转两种方式调整发动机的安装位置,改变推力作用点和方向,使其指向卫星质心变化范围的中心,以缩小推力相对卫星质心的偏心距,从而达到减小干扰力矩的目的。以某卫星490N发动机安装的工程实施为例,对比优化安装位置前后推力形成的干扰力矩的变化情况。结果表明:优化方法对减小干扰力矩能起到显著作用,可为工程中确定卫星变轨发动机安装位置及实施安装提供参考。     

控制力矩陀螺框架控制方法及框架转速测量方法

控制力矩陀螺是一种具有力矩放大特性的惯性执行机构,通常应用于大型航天器姿态控制。近年来,随着相关技术的发展,对基于控制力矩陀螺的中小卫星快速机动平台的需求日益迫切,这不仅需要控制力矩陀螺能够输出大力矩,而且要具有较高的力矩输出精度。本文结合工程实践,提出一种框架转速精度测量方法,以及一种采用正弦永磁同步电机,基于转子磁场定向的矢量控制方案。该框架控制方案中引入摩擦力矩观测器及其补偿算法,在控制回路中通过对摩擦力矩的补偿,可有效提高框架驱动控制系统的稳定性和动态性能。     

改善反作用轮低速性能的补偿观测器方法

基于Ｄａｈｌ摩擦模型,给出了用于卫星姿态三轴稳定控制的反作用轮低速动力学方程,就反作用轮转速过零对卫星姿态产生的扰动现象进行了分析,提出了一种利用非线性观测器估计摩擦力矩,并予以补偿的补偿观测器方法。仿真结果表明,该方法改善了反作用轮低速性能,提高了卫星姿态控制的指向精度和稳定度。     

基于数据表的载荷管理软件在轨工作自主控制设计

目前有效载荷在轨工作呈现多样化的趋势,为更好地适应这种多样化的任务,设计了一种在轨工作自主控制方案。该方案对多个型号的软件需求进行归纳整理和统筹分析,对在轨工作自主控制进行模块和功能划分,解决了多个载荷管理软件在轨工作控制需求差异化带来的多样化、定制化问题。通过引入可配置设计思路,建立数据表对载荷工作流程进行配置,解决了对特定载荷在轨工作流程的适配性问题,可实现多载荷多任务的在轨工作自主控制功能。该方法已在多个型号卫星的载荷管理器上使用,满足载荷单元工作流程多样化的要求。软件的重复使用不仅大大提高了软件设计和测试阶段的时间,缩短软件研制周期,还可以降低软件开发成本,并且提高软件整个研制阶段的可靠性。     

一种改进的观测器算法在制导中的应用

研究了导弹视线角和视线角速度可测情况下的制导信息估计问题,给出了一种改进的CB观测器(Cost-Based Observer)设计算法。基于非线性平面拦截模型,将目标机动看作一阶马尔可夫过程建立了制导信息滤波的非线性状态方程并将其化为SDC模型。针对系统能观性不足问题,提出了多状态相关系数矩阵加权组合的方案对CB观测器进行改进。并将其用于估计弹目相对距离、相对速度和目标机动加速度,利用估计的制导信息进行制导计算并与制导信息完全可测情况进行比较研究。最后,采用比例导引律进行仿真,结果表明本文所设计的观测器估计精度较高,且能满足制导性能要求。     

Design of face-hobbed spiral bevel gears with reduced maximum tooth contact pressure and transmission errors

The aim of this study is to define optimal tooth modifications, introduced by appropriately chosen head-cutter geometry and machine tool setting, to simultaneously minimize tooth contact pressure and angular displacement error of the driven gear (transmission error) of face-hobbed spiral bevel gears. As a result of these modifications, the gear pair becomes mismatched, and a point contact replaces the theoretical line contact. In the applied loaded tooth contact analysis it is assumed that the point contact under load is spreading over a surface along the whole or part of the ’’potential’’ contact line. A computer program was developed to implement the formulation provided above. By using this program the influence of tooth modifications introduced by the variation in machine tool settings and in head cutter data on load and pressure distributions, transmission errors, and fillet stresses is investigated and discussed. The correlation between the ease-off obtained by pinion tooth modifications and the corresponding tooth contact pressure distribution is investigated and the obtained results are presented.