Visual motion information provides a variety of clues that enable biological organisms from insects to primates to efficiently navigate in unstructured environments. We present modular mixed-signal VLSI implementations of the three most prominent spatio-temporal frequency tuned visual motion algorithms. A novel feature of these designs is the use of spike integration circuitry to implement the necessary temporal filtering. We show how such modular VLSI building blocks make it possible to build highly powerful and flexible vision systems. These three biomimetic motion algorithms are fully characterized and compared in performance. The visual motion detection models are each implemented on separate VLSI chips, but utilize a common silicon retina chip to transmit changes in contrast, and thus four separate mixed-signal VLSI designs are described. Characterization results of these sensors show that each has a saturating response to contrast to moving stimuli, and that the direction of motion of a sinusoidal grating can be detected down to less than 5 percent contrast, and over more than an order of magnitude in velocity, while retaining modest power consumption.
E. Ozalevli and C. M. Higgins, "Reconfigurable Biologically-Inspired Visual Motion Systems using Modular Neuromorphic VLSI chips," IEEE Transactions on Circuits and Systems I, 52(1), 79-92, January 2005.