关于刚体角速度定义的一个注解

给出了一种角速度定义方法. 这种方法基于固连坐标系基矢量和单位矢量的导数给出,但避免使用角速度矩阵概念. 另外从刚体上速度分布的角度,用速度场旋度的方法解释角速度. 可以帮助学生从另外一个角度来理解角速度概念.     

刚体的匀角速定轴转动状态是平衡态吗?

由刚体平衡的充要条件出发,证明了一般刚体的匀角速定轴转动状态不是平衡态;刚体只有绕其对称轴或通过质心的惯量主轴的匀角速转动状态才是平衡态.     

空间运动刚体角速度的一种形式

一般空间运动刚体角速度是理论力学教学的难点和重点,传统基于欧拉转动定理和坐标转换 矩阵的角速度引出方法存在各自的不足,于是可通过有限转动矩阵直接引出角速度,保存传 统两种方法的优点,利于学生更深刻理解角速度的概念.     

一般运动刚体角速度向量引入的一种新方法

通过向量运算给出了角速度向量引入的一种较简单的方法. 利用刚体上的固连向量的导数与其自身垂直的特点,得出反映刚体整体运动特性的角速度向量,并对这样的导出方法与刚体角速度向量物理意义之间的联系进行了讨论.     

Experimental validation of internal model approach for tracking control of a MEMS micromirror without angular velocity measurement

Nonlinear Dynamics - This paper addresses the angular tracking control for an electromagnetic MEMS micromirror. The problem is formulated in the output regulation framework for output feedback...     

一种引出一般运动刚体角速度概念的新方法

在刚体一般运动的教学中,角速度是学生接受起来比较困难的一个概念,通过矢量运算引入这一概念,为角速度的教学提供了一种新的简单方法.     

Full-field bubbly flow velocity measurements using a multiframe particle tracking technique

The study is an examination of two-phase dispersed air bubble flow about a cylindrical conductor emitting a constant heat flux. The technique of Particle Image Velocimetry is utilized in order to obtain a full-field non-invasive measurement of the resulting bubbly flow velocity field. The employed approach utilizes a flow visualization technique in which the instantaneous velocity profile of a given flow field is determined by digitally recording particle or bubble images within the flow over multiple successive video frames and then conducting a completely computational analysis of the data. The use of particle tracking algorithms which perform a point-by-point matching of seed images from one frame to the next allows construction of particle or bubble pathlines and instantaneous velocity field. Results were initially obtained for a synthetically created flow field and a single phase liquid convective field seeded with flow-following tracer particles. The method was additionally extended to measurements within a gas/liquid system in which bubble rise velocities over a substantial two-dimensional flow area were determined in order to demonstrate the effectiveness of the developed digital data acquisition and analysis methodology.A version of this paper was presented at the 12th Symposium on Turbulence, University of Missouri-Rolla, 24–26 September, 1990     

一种用于无陀螺捷联惯导系统的角速度融合算法

无陀螺捷联惯导系统(GFSINS)是用加速度计的合理空间组合解算出载体的角速度。载体角速度的解算精度是GFSINS的技术关键。在分析GFSINS九加速度计配置方案的基础上,提出一种新的角速度融合算法,消除该方案解算过程中开方计算及符号判断带来的误差。该算法还明显抵消了加速度计输出中包含的常值零点偏移误差和温度漂移误差等,具有实时性好、计算量小、通用性强的优点。仿真计算表明该算法可行,并能在一定程度上提高系统解算精度。     

Simulation of angular velocity sensor measurements using telemetry data on the motion of an object

An algorithm for the formation of smooth trajectories corresponding to telemetry data on the coordinates and orientation angles of a flying object with a strapdown inertial navigation system is proposed. Another algorithm of forming the angular velocity sensor measurements corresponding to this trajectory is developed. These algorithms allow one to analyze the accuracy of various numerical methods of determining the orientation of such system using the information on motions close to the real motions with known telemetry data.     

The attitudes of constant angular velocity motions

A rotation can be represented by a tensor which in turn can be parameterized by an angle of rotation and an axis of rotation. This paper presents the first systematic study of the class of rotation tensors which possess constant angular velocities. In addition to the expected rotations featuring constant axes of rotation and constant angular rates, the existence of two other types of rotation are shown. For these rotations, the time variation of the angle and axis of rotation are coupled by an integrable dynamical system. Although the temporal behavior of the axis and angle of rotation can be complex, it also demonstrated how the rotations can be considered as motions about the angular velocity vector. One of the methods used to show this result is based on an analogue to the geometry of a circular helix. The presence of the class of rotations in rigid body dynamics and twistless helical deformations of rods is also discussed.     

角色散FP干涉测速技术应用与分析

发展了固定腔结构的角色散FP干涉测速系统,干涉仪结构紧凑,采用固定腔标准具,实现了干涉 条纹永久免调,并且条纹常数的标定非常简单。该系统可用于靶面反射光强动态变化很大的场合,在电炮驱 动Mylar膜飞片实验中,光强变化达100倍时仍然获得了很好的结果。分析了标准具厚度误差、标准具端面 不平行、干涉条纹动态展宽和扫描图像畸变等因素对系统测量精度的影响以及系统的速度和时间分辨能力。     

测试爆炸箔起爆器的飞片速度

用双灵敏度VISAR测试爆炸箔起爆器的飞片速度历史。通过对飞片表面镀膜处理，消除了爆炸箔爆炸自发光产生的干扰，增加了飞片的反射率。在爆炸箔宽360 m，厚8.4 m，加速膛直径为1.2 mm，飞片厚0.12 mm，放电回路充电电压为4.5 kV，放电周期为750 ns的条件下，飞片最大速度为4.1 km/s，飞片加速时间约为150 ns，飞片达到最大速度的飞行距离约为0.3 mm。     

全加速度计惯性测量系统角速度解算方法的优化

全加速度计惯性测量技术是利用加速度计代替原来的陀螺来解算载体的姿态和位置信息。利用十二加速度计惯性组合配置方案的冗余信息,通过积分法、开平方法和迭代法解算出三种角速度,然后依据加权平均原理将上述三种角速度信息进行数据融合并对角速度进行补偿。经过算法补偿,解决了角速度误差随时间积累而发散的问题,同时解算精度得到了大幅提高。通过实验,将由全加速度计惯性测量系统输出信息解算出的角速度值与理论角速度值进行比较。通过对比,开平方法和迭代法相对于积分法对角速度解算误差的发散均有较好的抑制效果,应用加权平均法相比其他三种方法得到的角速度精度更高,且误差不随时间发散。为该研究领域提供了较好的参考。     

Optimal control of a rigid spacecraft programmed motion without angular velocity measurements

This paper considers the problem of optimal controlling a spacecraft programmed motion without its angular velocity measurements. An optimal control law that stabilizes this programmed motion and minimizes the cost that transfers the spacecraft from arbitrary initial state to the programmed state is obtained as a function of the kinematics attitude parameters and their estimates as well as the angle of programmed rotation. The stabilizing properties of the proposed controllers are proved using Liapunov techniques. Numerical simulation study is presented.     

Estimation and elimination of eigenvalue splitting and vibration instability of ring-shaped periodic structure subjected to three-axis angular velocity components

Meccanica - Stable operation is one of the most crucial requirements for resonators in vibratory gyroscopes and ultrasonic motors, but eigenvalue splitting can deteriorate operation stability. This...     

Development of a novel flow metering system using ultrasonic velocity profile measurement

 A new flow metering system using an ultrasonic Doppler method has been developed. By this method, an instantaneous velocity profile is measured and its integral is evaluated to give flow rate. Instead of making multidimensional flow mapping to evaluate its performance, the method was assessed in laboratory experiments where single line measurements were used over the whole pipe diameter or radius to determine the flow rate. The system shows a good capability of tracking transient flows. Its accuracy was investigated using the National Institute of Standards and Technology (NIST) flow standards in Gaithersburg, MD, USA; averaged results show its deviation from NIST results to be 0.18% for Re=400 K and 0.58% for Re=2.6 M. Good repeatability and reproducibility were also confirmed. Received: 28 April 2000/Accepted: 1 November 2000 Published online: 29 November 2001     

Technical-stability conditions for the rotation of a body on a vertical elastic rod

International Applied Mechanics -