Improving Angle-of-View for a 1-D Sensing Application by Using a 2-D Optical Sensor in “Cylindrical” Mode

Abstract

To further develop a low-power, low-cost optical motion detector for use with traffic detection under dark and daylight conditions, we have developed and verified a procedure to use a near-sensor image processing programmable 2-D optical sensor in a “1-D mode” to achieve the effect of using a cylindrical lens, thus improving the angle-of-view (AOV), the sensitivity, and usefulness of the sensor. Using an existing <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$256\times 256$</tex-math></inline-formula> element sensor in an innovative way, the AOV was increased from 0.4 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> to 21.3 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> in the vertical direction while also improving the sensitivity. The details of the sensor hardware architecture are described in detail and pseudo-code for programming the sensor is discussed. The results were used to demonstrate the extraction of local extreme points used for time-to-impact calculations to estimate the speed of an approaching vehicle.