大型天文望远镜高精度摩擦传动的研究

High precision friction drive of large telescope

提出了一种大型天文望远镜高精度摩擦传动的光学检测机构,用来检测主、从动轮旋转轴线的扭转角。并设计了相应的调整机构。利用这套机构使得主、从动轮的扭转夹角控制在30″以内。实验结果表明,在运行过程中没有出现抖动现象。传动系统长时间平稳运行的低速可达0.2″/s,运动位置精度RMS值为0.01″左右。30min内低速可达0.05″/s,位置精度RMS值为0.009″左右。正弦运动幅值30′,最大速度36″/s,最大加速度为0.18″/s2。这些指标满足了LAM OST天文望远镜的技术要求。克服了由于安装等原因导致旋转轴线之间存在扭转角,进而使得天文望远镜所跟踪的目标在视场中出现抖动,甚至严重会漂移出视场的局限,实现了外圆摩擦传动主、从动轮旋转轴线在空间平行的理想位置。

A kind of optical detecting mechanism is proposed to detect the skew angle between the axes of contact roller and wheel in high precision friction drive system adopted in large astronomical telescopes. The mechanism to adjust the skew angle is also given. With the help of these mechanisms, the skew angle between roller and wheel axes is controlled below 30″. The results of experiments show that there is no skip during the movement and the friction drive can achieve high precision at ultra slow speed. The lowest long-steady velocity of the experiment drive system is 0.2″/s with corresponding precision 0.01″(RMS), and during 30′ the lowest steady velocity is 0.05″/s with corresponding precision 0.009″(RMS). The precision of the variable velocity motion is (0.1)″(RMS) with the corresponding amplitude 30′, maximum velocity 36″/s, maximum acceleration 0.18″/s^2. All these experiment results meet the LAMOST's specifications. The problem of object image tracked by telescope stirring in the field of view, what is more, drifting off the field of view caused by skew angle between axes of contact roller and wheel is solved by these mechanisms. The axes of roller and wheel can be kept in the ideal position in friction drive system.