光纤陀螺数字闭环控制系统模型实验研究

数字闭环光纤陀螺的动态性能受控制系统设计的影响.根据光纤陀螺数字闭环检测过程,建立了控制系统的数学模型.为在全频带内对模型进行验证,提出了基于Faraday效应的光纤陀螺频率响应测试方法,对该测试方法与角振动台测试方法的等效性进行了分析.设计了频率响应测试系统,测试范围大于50 kHz,波形失真小于0.1%.实测了采用一阶积分控制算法的数字闭环光纤陀螺频率响应.实验结果表明模型误差小于8%.     

The phenomenon of weight-reduction of a spinning wheel

An investigation has been conducted into the controversial phenomenon of weight-reduction of spinning wheels. When subjected to forced precession and controlled lifting, a spinning wheel does indeed lose 8% of its weight, as measured by a load-cell. That is, some of the gravitational potential energy acquired during lifting is supplied by the horizontal input force causing the enhanced precession. Consequently, the averaged vertical lifting force is less than Mg. The explanation for this phenomenon follows directly from the requirement of energy conservation throughout the process.     

On the relation of Thomas rotation and angular velocity of reference frames

In the extensive literature dealing with the relativistic phenomenon of Thomas rotation several methods have been developed for calculating the Thomas rotation angle of a gyroscope along a circular world line. One of the most appealing concepts, introduced in Rindler and Perlick (Gen Rel Grav 22:1067, 1990), is to consider a rotating reference frame co-moving with the gyroscope, and relate the precession of the gyroscope to the angular velocity of the reference frame. A recent paper (Herrera and di Prisco in Found Phys Lett 15:373, 2002), however, applies this principle to three different co-moving rotating reference frames and arrives at three different Thomas rotation angles. The reason for this apparent paradox is that the principle of Rindler and Perlick (Gen Rel Grav 22:1067, 1990) is used for a situation to which it does not apply. In this paper we rigorously examine the theoretical background and limitations of applicability of the principle of Rindler and Perlick (Gen Rel Grav 22:1067, 1990). Along the way we also establish some general properties of rotating reference frames, which may be of independent interest.