A super parallel vision system implemented with mixed analog and digital circuits

本研究的目的是开发一种新型的视觉系统，能够实现模拟/数字混合结构的实时图像处理。因此，我们设计并制作了由硅视网膜、模拟超大规模集成电路(VLSI)和现场可编程门阵列组成的系统。(Fpga)。硅视网膜模拟脊椎动物视网膜的持续和瞬时反应。模拟持续响应的输出具有类似Palladian-Gauss的感受场，从而对输入图像进行平滑和对比度增强。模拟瞬时响应的输出是通过减去由电阻网络平滑的连续图像而获得的。这两个通道的输出可以在室内照明下，在不超过几十毫秒的时间延迟内，从硅视网膜实时交替获得。芯片的输出是偏移抑制的模拟电压，因为晶体管特性的不可控失配借助嵌入在每个像素电路中的采样/保持电路来补偿。来自硅视网膜的模拟输出通过A/D转换器传输到FPGA，代表具有这些通道的经预处理的图像。由现场可编程门阵列完成边缘检测、目标跟踪、深度感知等数字图像计算。本文开发的并行视觉系统在机器人视觉、多媒体等领域具有广泛的工程应用前景。

The purpose of the present research is to develop a novel vision system that can carry out the real-time image processing with mixed analog/digital architecture. Accordingly, we have designed and fabricated the system consisting of a silicon retina, an analog Very Large Scale Integrated (VLSI) circuit and Field Programmable Gate Array. (FPGA). The silicon retina emulates the sustained and the transient responses found in the vertebrate retina. The output emulating sustained response possesses a Palladian-Gaussian-like receptive field and therefore carries out a smoothing and contrast-enhancement on input images. The output emulating the transient response was obtained by subtracting consecutive images that were smoothed out by the resistive network. The outputs of these two channels can be obtained alternately from the silicon retina in real time, within time delays not exceeding a few tens of ms, in indoor illumination. The outputs of the chip are offset-suppressed analog voltages since uncontrollable mismatches of transistor characteristics are compensated for with the aid of sample/hold circuits embedded in each pixel circuit. The analog outputs from the silicon retina representing the preprocessed image with these channels are transferred to the FPGA through a A/D converter. The FPGA carries out digital image computations such as edge detection, target tracking and depth perception. The parallel vision system developed in the present study is readily used in a variety of engineering applications such as the fields of robot vision and multi-media.