【作者】 贾银亮；

【导师】 张焕春；

【作者基本信息】 南京航空航天大学 ， 测试技术与仪器， 2011， 博士

【摘要】 驱动彩色液晶显示器的图形生成技术是航空电子技术的一项关键技术，其核心内容包括图形的高速实时生成和图形的反走样等。国外航空座舱电子综合图形显示技术已相当成熟，上世纪90年代已大量应用。我国在机载图形综合显示系统领域曾经比较落后，近10年来加快了研究步伐，目前已经取得了一定成果。国内产品已应用在某些型号的国产飞机上，但技术与国际先进水平比还有差距。本文针对飞机座舱综合图形显示系统基本画面及其组合画面的特点，对图形生成、硬件加速技术和反走样技术展开研究，主要包括以下几方面：根据图形显示画面的特点，提出了一套基于FPGA+DSP的飞机座舱综合图形显示系统实现方案：用FPGA作为主处理器，完成图形的生成；用DSP作为协处理器，完成少量参数计算；并使用双帧存保存待显示的图形。提出并开发了原理样机，该方案能实现高分辨率、大屏幕的显示，有效的提高了飞机座舱综合图形显示系统的性能，通过在DSP提供通用函数库，大大简化了软件的开发流程。结合座舱图形显示系统画面的绘制，在分析现有的直线生成算法的基础上，针对经典的Bresenham算法一次只能生成一个像素，效率较低的缺点，提出新的改进算法。该算法通过递推运算，每次可以生成一个像素行，提高了算法效率。在此基础上，借鉴双步直线算法的思想，进一步提出多像素行直线算法，一次可以生成两个像素行，进一步提高了效率。这些算法仍保持了Bresenham算法计算简单的特点，可以由FPGA实现，提高了直线生成速度。研究了直线、圆和字符的反走样算法。提出一种新的直线反走样算法，在保证反走样效果的基础上，简化计算，提高了算法的效率。针对飞机座舱图形显示中需要绘制三像素宽直线，把新的反走样算法应用到多像素宽的直线绘制，提出了多像素宽直线反走样绘制的方法。针对现有圆的反走样生成算法计算复杂，反走样效果一般的缺点，提出了一种基于中点画圆法的整数反走样算法，通过省略高次项来简化计算，并用简单的计算修正省略带来的误差以保证精度。为了简化计算，针对64级灰度的圆弧反走样，提出了相邻像素的灰度递推方法，利用整数移位、加法和比较来实现反走样。研究并设计了基于FPGA的字符的反走样方法。设计的几种反走样算法结构简单，反走样效果较好，由于避免了浮点和除法运算，便于FPGA实现。在基于FPGA+DSP的平台上，实现了水平状态指示仪画面的生成。DSP计算直线和字符旋转后的位置，FPGA根据这些位置来生成整个画面。系统通过对称性减少了DSP的计算量；通过并行运算提高了效率；通过重画旧画面提高了消隐速度。理论分析和实际调试都证明，该方案提高了画面的生成速度，并简化了帧存的总线设计。针对全姿态指示仪画面的特点，提出了一种基于FPGA+DSP的生成方法，该方法预测地平线各像素行的像素数量，使用水平线作为扫描线进行填充，并在填充的过程中适时的计算地平线上那些作为扫描线端点的像素和边界点的坐标，简化了填充前的初始化计算，减少了帧存访问量，提高了画面的生成速度。更多还原

【Abstract】 The design of graphics generator for driving LCD is a key technology of avionic system andrun-time generation and antialiasing of graphics are main contents of it. Foreign technology ofcombined graphics display system was researched and used on aircraft from90decade last century. Inthis field, our country once dropped behind and fast grown up in last10years. Now, products in homeare used on some aircrafts, but the technology still drops behind. In this paper, according to thecharacteristics of the combined graphics display system in aircraft cockpit, graphics generation,accelerating and anti-aliasing techniques were discussed. Furthermore, some novel design methodswere researched and advanced.Researching on the graphics generation in aircraft cockpit’s combined graphics display system, anew design method for the graphics system based on FPGA and DSP was proposed and a prototypemachine was developed, according to the characteristics of the graphics. In order to improve theperformance of the system, FPGA was used as main processor to generate graphics and DSP was usedas coprocessor to count few parameters while double frame buffers were used. The system acceleratedthe graphics drawn by FPGA, and the resolution was improved. Software development waspredigested using general functions library on DSP.According to the generation of the graphics in aircraft cockpit, a new algorithm was developedfor line generating after reaching on fundamental algorithms. Canonical Bresenham algorithm canonly generate one pixel of a line each time. The new algorithm can generate pixels of a line row byrow and inherit the advantages of Bresenham algorithm without division and decimal fraction, so itsefficiency was proved to be better. Using for referent of two-step algorithm, a novel method wasproposed to gengeate two rows of a line each time. These algorithms can be realized by FPGA toincrease the speed of lines drawing.Researching on the antialiasing algorithms for line, character and circle, a new algorithm waspresent for line antialiasing using integer shift, addition and compare to find the grayscale of eachpixel, and the antialiasing speed was improved. Because the graphics in aircraft cockpit include threepixels wide lines, a new method for arbitrary wide line generation wae proposed based on the newline antialiasing algorithm. Antialiasing for circle was complex and the effect of algorithms inexistence was not satisfactory. To improve efficiency and effect, an integral algorithm was present forcircle anti-aliasing based on midpoint generating algorithm. The new algorithm found the grayscale ofeach pixel according to the distance between the center of a pixel and the circle. The algorithm abandoned the high-order epsilon and corrected the error by simple calculation. A method was built todraw a circle with64levels of grayscale by forecasting the grayscale change between neighbouringpixels using integer shift, addition and compare without floating-point and division. The algorithm forcharacter antialiasing was also researched. The new algorithms were convenient to realize onhardware. The algorithms proved to be efficiently and effective.A project was present based on FPGA for horizontal Indicator in Aircraft Cockpit. Graphics weregenerated, memory and LCD were controled by FPGA according to the positions of words and linescounted by DSP. Less calculation and time were needed by utilizing the symmetry of graphics,parallel counting and old graphics regenerating. The project was proved to be better and faster withsimply bus.Attitude Indicator in Aircraft Cockpit spends much time on generating graphics and a newalgorithm based on FPGA was present. The algorithm got the coordinate of a scanning beam point ofthe horizon and used level line to fill. The horizon and profile were counted while filling. Lesscalculation was needed before filling to generate the graphics with less memory accessing, so thegraphics of attitude Indicator were generated faster.更多还原