We present three di#erent architectures that make use of analog VLSI velocity sensors for detecting the focus of expansion, time to contact and motion discontinuities respectively. For each of the architectures proposed we describe the functionality of their component modules and their principles of operation. Data measurements obtainedfrom the VLSI chips developed demonstrate their correct performance and their limits of operation. 1: Introduction Analog velocity sensor circuits have been thoroughly investigated in the past years #19,2,1,7,4,17,5#. Nonetheless, researchers were unable to obtain a device that would simultaneously be compact, robust to background brightness level, insensitivetostimulus contrast and have a wide, unambiguous, range of speed selectivity. Recently novel velocity sensors that are sensitive to low contrast stimuli, independentofcontrast #for intermediate and high contrast values#, selectivetoover 3 orders of magnitude of velocityandover 2 orders of magnitu...

A partial review of neuromorphic vision sensors that are suitable for use in autonomous systems is presented. Interfaces are being developed to multiplex the high-dimensional output signals of arrays of such sensors and to communicate them in standard formats to o#-chip devices for higher-level processing, actuation, storage and display. Alternatively, on-chip processing stages may be implemented to extract sparse image parameters, thereby obviating the need for multiplexing. Autonomous robots are used to test neuromorphic vision chips in real-world environments and to explore the possibilities of data fusion from di#erent sensing modalities. Examples of autonomous mobile systems that use neuromorphic vision chips for line tracking and optical flow matching are described. Keywords: vision, motion, optical flow, focal-plane array, retina, neuromorphic, analog VLSI, tracking 1. INTRODUCTION Neuromorphic vision sensors and preprocessors are increasingly being used to implement the firs...

A robust, integrative algorithm is presented for computing the position of the focus of expansion or axis of rotation (the singular point) in optical flow fields such as those generated by self-motion. Measurements are shown of a fully parallel CMOS analog VLSI motion sensor array which computes the direction of local motion (sign of optical flow) at each pixel and can directly implement this algorithm. The flow field singular point is computed in real time with a power consumption of less than 2 mW . Computation of the singular point for more general flow fields requires measures of field expansion and rotation, which it is shown can also be computed in real-time hardware, again using only the sign of the optical flow field. These measures, along with the location of the singular point, provide robust real-time self-motion information for the visual guidance of a moving platform such as a robot. 1 INTRODUCTION Visually guided navigation of autonomous vehicles requires robust measures...

. We introduce several different focal plane analog VLSI motion sensors developed in the past. We show how their pixel-parallel architecture can be used to extract low-dimensional information from a higher dimensional data set. As an example we present an algorithm and corresponding experiments to compute the focus of expansion, focus of contraction and the axis of rotation from natural visual input. A fully integrated system for real-time computation of these quantities is proposed as well. In computer simulations it is shown that the direction of motion vector field is best suited to perform the algorithm even at high noise levels. 1 Analog VLSI Motion Sensors In the past the computer vision communityhas invested much effort into developing motion detection algorithms; for a critical review see [BFB94]. Implementing these algorithms in real-time systems proved challenging for computational reasons. Additionally it has been realized that a motion vector field is useful mainly as star...

We present di#erent compact analog VLSI motion sensors that compute the 1-D velocity of optical stimuli over a large range and are suitable for integration in focal plane arrays.Theyhavebeen extensively tested and optimized for robust performance under varying light conditions. Since their output signals are only weakly dependent on contrast, they directly extract optical #ow data from an image. Focal plane arrays of such sensors areparticularly interesting for application in single-chip systems that perform navigation tasks for moving robots or vehicles, where light weight, low power consumption, and real-time processing are crucial. Several monolithic motion-processing systems based on such velocity sensors have been built and tested. We describehere three chips, designed for the determination of the focus of expansion, the estimation of the time to contact, and the detection of motion discontinuities respectively. The #rst two systems have been speci#cally designed for vehicle navig...