<p>For an image-based tracking loop system of tip-tilt mirror, the traditional control methodologies mainly include a single-position loop or two-position loop. The most effective method for enhancing tracking performance is to increase control gain for a high bandwidth. However, the image sensor sampling rate and time delay engendered by data processing restricts the bandwidth. Therefore, a position-rate control method is proposed to improve the performance of a tip-tilt mirror control system. The angular rate of tip-tilt mirror is calculated from the angular position measured by the linear encoder. The open-loop rate transfer function of tip-tilt mirror features differential in the low-frequency domain because the original tip-tilt control system is zero-type. When the inner rate feedback loop is implemented, an integrator is introduced into the original position loop. A PI (proportional-integral) controller can stabilize the position loop such that two integrators are in the tracking loop, so the low-frequency performance can be improved compared to the original control method. The experimental results coincide with the theoretical analysis and then verify the correctness of the presented theories.</p>
To meet the demand of complicated ATP system to control in real time and smoothly, this paper selects fiber channel as the data transmission mode. It designs a star-shaped electrical platform which can combine data acquisition, processing, transmission, and exchange in one. Also by using Rocket I/O GTX transceiver embedded in Xilinx Virtex-6 FPGA as the physical layer, it implements real-time data transmission and exchange basing on 24 fiber channels to support up to 128 custom serial protocols. The main points of electrical platform design are presented in this paper. Furthermore, the method of FPGA implementation and major configuration parameters of Rocket I/O GTX transceiver are discussed in detail. Also the experimental results of hardware debugging in ISE environment show that the 24 fiber channel transmission is stable and right when the system reference clock is 250MHz, single-channel line rate is 2.5Gb/s. The use of fiber channel has improved data transmission efficiency and reliability between the units of ATP system. Also hardware debugging workload is significantly reduced by universal configurable software design.