Multiple-beam optical position sensor for automotive occupant detection

摘要

An optical sensor system for measuring the approximate three-dimensional profile and position of an object. A reduced to practice embodiment of the optical sensor system has been used to measure the three-dimensional profile and position of an object within a range of 40 inches to 2 inches with high accuracy and high update rates (>1 KHz). The sensor system generates a set of optical beams using a projection lens and multiple light emitting diodes (LED) located in a back focal plane of the projection lens. The position of each LED determines the angle of a beam transmitted thereby. By turning on each LED sequentially in time, a set of beams is generated at various angles that illuminates the object to produce a set of spots on the object. The range from each LED to each of the spatially-separated illuminated spots on the object is determined by imaging the spots onto a two-dimensional transverse-effect photodiode. Signals derived from a pair of photocurrent outputs from the photodiode are processed to determine the positions of the spots on the two-dimensional transverse-effect photodiode. Computations are performed that implement optical triangulation to determine the range and approximate three-dimensional profile to the object.