公开(公告)号：US06470291B1

公开(公告)日：2002-10-22

申请号：US09404604

申请日：1999-09-24

申请人： Turguy Goker ,  Edward H. Patrick ,  Stanley S. Tang

发明人： Turguy Goker ,  Edward H. Patrick ,  Stanley S. Tang

IPC分类号： G11B1552

CPC分类号： G11B15/54

摘要： To provide accurate measurement of rotational velocity and an adequate bandwidth for servo control as a function of the measurement over a wide range of velocities, the present invention utilizes unique speed computation algorithms based on a combination of fine and coarse shaft velocity measurements from a tachometer. The preferred embodiments utilize control signals derived from the velocity measurements to control motor speed, for example, to provide servo control of a digital tape drive. The preferred embodiments utilize an optical encoder coupled to a reel-shaft to generate tachometer pulses as the shaft rotates. The coarse measurement may actually take two different forms for different speed ranges. In one range, this measurement involves counting the number of pulses in a sampling interval. In the other range, the coarse measurement entails counting the number of sampling intervals per detection of a tachometer pulse. The fine velocity measurement is based on detection of differences in time delays between certain ones of the tachometer pulses and the edges of one or more of the sampling intervals. The delay detections may entail counting pulses of a clock signal, which has a rate substantially higher than the sampling rate, for periods between certain tachometer pulses and the edges of one or more of the sample intervals. The fine measurements provide a correction in the speed calculation for variations in phase relationship between the sampling and the tachometer pulses.

摘要翻译： 为了提供作为在宽范围速度上的测量的函数的伺服控制的旋转速度的准确测量和足够的带宽，本发明基于来自转速计的精细和粗略轴速度测量的组合来利用独特的速度计算算法。 优选实施例利用从速度测量得到的控制信号来控制电机速度，例如提供数字磁带驱动器的伺服控制。 优选实施例利用耦合到卷轴的光学编码器来随着轴旋转而产生转速计脉冲。 对于不同的速度范围，粗略测量实际上可能采取两种不同的形式。 在一个范围内，该测量涉及对采样间隔内的脉冲数进行计数。 在另一个范围内，粗略测量需要对每个检测到转速计脉冲的采样间隔数进行计数。 精细速度测量是基于检测到某些转速计脉冲之间的时间延迟与一个或多个采样间隔的边沿之间的差异的检测。 对于在某些转速计脉冲与一个或多个采样间隔的边沿之间的周期，延迟检测可能需要对具有明显高于采样速率的速率的时钟信号的计数脉冲。 精细测量提供了在采样和转速计脉冲之间的相位关系变化的速度计算中的校正。