A CMOS expansion/contraction motion sensor with a retinal processing circuit for Z-motion detection applications

Abstract

A design of CMOS expansion/contraction motion sensor based on the artificial retinal sensor array and digital correlation circuitry for real-time detecting object motion and velocity in the longitudinal +Z/-Z-directions (Z-motion) is proposed. To cope with the non-uniform nature in optic field of Z-motion, we compute the correlation between one set of output of retinal sensors and the delayed output of the other set of far-end sensors at progressive increasing distances across the chip for motion and velocity detection. Sweeping the correlation delay value in one signal path of the correlator, the chip can indicate the strongest correlation when the correlation delay is tuned to match the actual velocity. Behavior-level MATLAB simulations have been performed to successfully validate the functionity of the proposed motion detection method using expanding or contracting motion images that are incurred from an out-bound or in-bound moving object at a constant Z-velocity. The proposed motion sensor consists of 1448 sensor pixels placed on thirty-two evenly spaced divergent axes with 25 correlator outputs on each axis. Z-Motion and velocity detection is performed based on the maximum likelihood (ML) detection using the 25 correlators output of all 32 axes. The chip is designed in 0.35-um CMOS technology and the core occupies approximately 5600 x 5600 mu m(2) with a fill factor of 11%.