天问一号高分辨率相机反熔丝FPGA软件系统设计

Design of Tianwen-1 high-resolution camera anti-fuse FPGA software system

天问一号执行的任务属于深空探测任务,其上高分辨率相机主控单元工作时间较长,为了提高主控FPGA的抗单粒子效应及可靠性,选用反熔丝FPGA进行软件系统设计。其中,主控FPGA管理的调焦单元、时间码守时校时等功能为安全关键项目。为提高软件的健壮性,主控FPGA根据调焦机构的光机结构,设计基于加减速曲线的二细分控制方法,在满足调焦速度的前提下,避开机构共振频率,实现步进电机驱动调焦机构平稳的运转;同时,天问一号环绕器在环火段位置时,高分相机需要执行拍摄任务,拍摄指令为延时指令,对时间有较高要求,在此基础上主控FPGA设计时间码守时校时功能,确保高分相机在任务段精确执行拍摄任务。实验结果表明:调焦机构速度爬升时间为112.2 ms;时间守时的精度为1.25 s。实现了调焦单元的平稳运行和可靠的守时系统。

In the context of deep-space exploration,such as the Tianwen-1 mission,reliability over a long working time is an essential requirement for the main control unit of the high-resolution camera. To improve the anti-single event effect and reliability of the master FPGA,an anti-fuse FPGA is used for the software system design. Functions such as focusing unit control,time code punctuality,and time correction,managed by the master FPGA,are safety-critical items. To improve the robustness of the software,the main control FPGA design employs a two-division control method based on the acceleration and deceleration curve for the optical-mechanical structure of the focusing mechanism. A stepper motor driver is used to match the focusing speed and avoid the resonance frequency of the mechanism,for the focusing mechanism to run smoothly;at the same time,when the Tianwen-1 surround is in the ring fire section,the high-resolution camera needs to perform shooting tasks by following delayed commands,creating a requirement for highly accurate timing. Thus,the master control FPGA design must ensure time code punctuality and timing function such that the high-resolution camera accurately executes the shooting task. The experimental results show that the movement time of the focusing mechanism is 112. 2 ms and the accuracy of time keeping is 1. 25 s. The design satisfies the requirements of a stable operation of the focusing unit and reliable timing.