A Low-Power Visual-Horizon Estimation Chip

Recent successes in the construction of micro aerial vehicles (< 15 cm) have highlighted the lack of real-time sensors for flight control. This paper describes a low-power real-time visual-horizon sensor for stabilizing the pitch and roll of miniature aircraft in moderate-to-high-altitude flight. This prototype sensor uses a 12 times 12 photoreceptor array to find a best-fit horizon line based on image intensity. The sensor includes a "confidence-level" output for signaling poor sensing conditions and can scan out the image. The chip was fabricated in a commercially available 0.5- mum CMOS process and operates on less than 2.5 mW with a 5-V power supply.