Converting spatially encoded sensory information to motor signals using analog VLSI circuits

A collective computational architecture and real-time, analog VLSI implementation for localizing and tracking a stimulus in a sensory image are developed. This architecture is presented as a layered two-dimensional computationalframework which generates signals to autonomously control a mechanical system that tracks the stimulus. The framework is a schematic representation of the described computation. The input to the framework is a spatially encoded sensory image and the outputs are a set of pulse trains that are used to control a robotic motor system. The analog VLSI implementation is based upon circuits that provide a real-time, small-size, low-power implementation technology for this and other sensorimotor applications. The circuits perform the desired computation entirely in parallel on a single VLSI chip. The layer-to-layer communications occur via arrays of currents which are modified at each level in the framework and then communicated to the subsequent layer. The outputs generated by the circuit are a set of pulse-encoded signals sufficient to antagonistically control DC actuators. A system implementation and resulting data are also presented. The system combines a visual imaging array, computational circuitry, and a mechanical plant, which, through negative feedback, moves the imager to hold a stimulus (a bright spot on a darker background) stationary in the sensory field.