光纤陀螺随钻测斜仪钻进中井眼轨迹测量方法研究

为提高光纤陀螺随钻测斜仪的井眼轨迹的测量精度,采用卡尔曼滤波组合的测量方法,对井斜、方位和工具面失准角进行估计。由于姿态失准角的估计精度与其可观测性密切相关,为了提高估计精度,文章分别在匀速、匀加速和匀速转动三种钻进运动状态下,采用分段线性定常系统(PWCS)和奇异值分解(SVD)的方法分析了姿态失准角的可观测性,并分析了钻进中井斜角和转动速率对姿态失准角估计精度的影响。由仿真结果可知,匀速钻进时,方位失准角不可观测;匀加速钻进时,方位失准角可观测且在水平井中可观测性最强,随着井斜角度增大,方位角、井斜角的测量精度逐渐提高;绕轴向匀速转动钻进时,方位失准角的可观测性和估计精度均优于匀速、匀加速钻进状态;角速率由0°/s增加到5°/s时,三个姿态失准角的估计精度均增大并逐渐趋于稳定。文中提出的轴向转动钻进运动可有效提高井眼轨迹的测量精度。     

机械振动对光学系统指向精度的影响

针对机械振动对光学系统性能影响的预测问题，基于矩阵光学和机械振动学理论，建立了振动响应对光学系统性能失调和光束稳定性的分析模型，并以某光学系统为例，给出了数值仿真方法。数值结果表明，仿真模型是合理的，可用于预测评价光学平台机械结构设计的优劣。     

Uncertainty evaluation associated with versatile automated gauging influenced by process variations through design of experiments approach

Recent advances in versatile automated gauging have enabled accurate geometric tolerance assessment on the shop floor. This paper is concerned with the uncertainty evaluation associated with comparative coordinate measurement using the design of experiments (DOE) approach. It employs the Renishaw Equator which is a software-driven comparative gauge based on the traditional comparison of production parts to a reference master part. The fixturing requirement of each production part to the master part is approximately ±1 mm for a comparison process with an uncertainty of ±2 μm. Therefore, a number of experimental designs are applied with the main focus on the influence of part misalignment from rotation between master and measure coordinate frames on the comparator measurement uncertainty. Other factors considered include measurement mode mainly in scanning and touch-trigger probing (TTP) and alignment procedure used to establish the coordinate reference frame (CRF) with respect to the number of contact points used for each geometric feature measured. The measurement uncertainty analysis of the comparator technique used by the Equator gauge commences with a simple measurement task using a gauge block to evaluate the three-dimensional (3D) uncertainty of length comparative coordinate measurement influenced by an offset by tilt in one direction (two-dimensional angular misalignment). Then, a specific manufactured measurement object is employed so that the comparator measurement uncertainty can be assessed for numerous measurement tasks within a satisfactory range of the working volume of the versatile gauge. Furthermore, in the second case study, different types of part misalignment including both 2D and 3D angular misalignments are applied. The time required for managing the re-mastering process is also examined. A task specific uncertainty evaluation is completed using DOE. Also, investigating the effects of process variations that might be experienced by such a device in workshop environments. It is shown that the comparator measurement uncertainties obtained by all the experiments agree with system features under specified conditions. It is also demonstrated that when the specified conditions are exceeded, the comparator measurement uncertainty is associated with the measurement task, the measurement strategy used, the feature size, and the magnitude and direction of offset angles in relation to the reference axes of the machine. In particular, departures from the specified part fixturing requirement of Equator have a more significant effect on the uncertainty of length measurement in comparator mode and a less significant effect on the diameter measurement uncertainty for the specific Equator and test conditions.     

Robust adaptive relative position and attitude control for spacecraft autonomous proximity

This paper provides new results of the dynamical modeling and controller designing for autonomous close proximity phase during rendezvous and docking in the presence of kinematic couplings and model uncertainties. A globally defined relative motion mechanical model for close proximity operations is introduced firstly. Then, in spite of the kinematic couplings and thrust misalignment between relative rotation and relative translation, robust adaptive relative position and relative attitude controllers are designed successively. Finally, stability of the overall system is proved that the relative position and relative attitude are uniformly ultimately bounded, and the size of the ultimate bound can be regulated small enough by control system parameters. Performance of the controlled overall system is demonstrated via a representative numerical example.     

考虑啮合错位的斜齿轮复合修形优化研究

为了减少斜齿轮传动因啮合错位导致的齿面偏载、传递误差增大、啮合冲击增大,研究考虑啮合错位的斜齿轮复合修形方法,讨论修形前后不同错位量下齿面啮合性能的变化规律。该方法考虑了啮合错位对齿轮啮合性能的影响,基于斜齿轮啮合接触计算模型,以齿面载荷分布、传递误差、啮合冲击等性能指标为评价依据,进行了“螺旋角修形+齿廓鼓形修形”的复合修形。结果表明：基于多目标的“螺旋角修形+齿廓鼓形修形”复合修形能有效改善因啮合错位造成的齿向偏载,且在降低传动误差峰峰值和改善啮合冲击方面显著优于单一的螺旋角修形,能较全面地改善斜齿轮的啮合质量。     

带标准分度转台的激光角度干涉仪的不准直误差模型

为了探讨带标准分度转台的激光角度干涉仪在测量过程中的安装不准直误差对测量结果的影响,在分析回转轴转角误差测量原理的基础上,根据测量光路的几何特征变化规律,提出测量系统的不准直误差模型。研究不准直误差变化对转角误差测量结果的影响,明确了为保证最终测量结果的精度在±1″内宜采取的误差控制措施。通过与自准直仪配合高精度多面棱体方法进行比对实验,并利用不准直误差模型对测量结果进行修正后,可以将测量结果的最大差值减小为-0.52″。结果表明所建立的误差模型的正确性,在准确评估和提高测量系统的精度上有一定的推广价值。     

CO2激光器虚共焦腔凸面镜失调的实验研究

高功率激光器工作时，由于谐振腔反射镜上的光强分布不均匀，会导致镜面温度不均匀，从而造成镜面的角向偏转，致使激光器光轴发生偏转，严重影响输出光束质量，甚至造成不出光。文中主要从实验研究了CO2激光器虚共焦腔凸面镜失调对激光器输出光束质量的影响，实验结果表明，当凸面镜失调角接近于由理论计算而得的失调临界角时，输出光斑约为半个圆环，与理论分析非常符合，当凸面镜失调角达到约为失调临界角的4．5倍时，完全停止振荡。     

光栅对压缩器在刻线不平行时的色散研究

针对光栅对压缩器刻线平行性失调会对压缩器色散特性造成严重影响这一问题,对刻线不平行的光栅对压缩器的衍射特性进行了分析,推导出了脉冲光束通过光栅对的光程。数值计算了2阶、3阶和4阶色散量,以及与光栅对严格平行相比的色散差。计算了输出脉冲的垂直谱位移,并将其作为刻线夹角的函数进行了分析。结果表明,存在刻线失调时,低刻线密度的光栅具有更好的优越性。     

基于GP-SRCDKF的初始对准技术研究

随着对惯性导航系统中对准时间要求的不断提高,初始对准需要在大方位失准角条件下进行,此时需采用非线性滤波方法来实现初始对准。基于此,提出高斯过程回归平方根中心差分卡尔曼滤波算法(GP-SRCDKF)。将高斯过程回归融入到SRCDKF算法中,利用高斯过程得到系统回归模型及噪声协方差,用回归模型代替状态方程和观测方程,对相应的噪声协方差进行实时自适应调整。该算法不仅克服了扩展卡尔曼滤波滤波精度低、需要计算雅可比矩阵的不足,而且可解决传统滤波容易受系统动态模型不确定和噪声协方差不准确的限制。仿真实验结果验证了该算法的有效性和优越性。     

加速过程偏角不对中轴系横向振动特性研究

建立了非稳态油膜力作用下，偏角不对中碰摩轴系的动力学模型，通过引入轴系问的位移约束，由Lagrange方程导出了不对中轴系的振动方程，研究了加速条件下，轴系横向振动特性随加速度、偏角不对中量的变化规律．研究表明：偏角不对中的存在，增强了系统的非线性和运动耦合；偏角不对中、轴承油膜、局部碰摩等因素一起，通过自激励、参数激励和外激励等方式激起了轴系的非线性振动响应；加速工况下，偏角不对中轴系横向振动出现了新的共振特性．