Surface distance determination using reflected light

摘要

A distance between a light source and a surface may be determined by emitting pulses of light from the light source and measuring an intensity of the light after the light reaches the surface. To determine a true distance, aliased distances, which are outside of a known distance segment, are disregarded. The distance segment may be defined by a modulation period of light emitted by the light source. The distance segment may be determined based on a ratio of a measured intensity of light captured during a first time interval and a second time interval, and a comparison of other types of evidence data that identifies a correct distance segment. The evidence data may include data associated with the amplitude (intensity) of the light captured, temporal variations in data, and/or analysis data collected from other surfaces that are adjacent to the surface.

主权项

1. A system to measure distances, the system comprising:
a light source to emit pulses of light, the pulses emitted at a frequency; two light sensors to detect light that is emitted from the light source and reflected off of a surface, the two light sensors including:
a first light sensor to measure an intensity of light detected during a first time interval to determine a first measured value, anda second light sensor to measure an intensity of light detected during a second time interval, equal to the first time interval, to determine a second measured value, wherein the first light sensor is off during the second time interval and the second light sensor is off during the first time interval; andone or more processors to:determine a ratio of the first measured value to the second measured value;select a distance segment from a plurality of equal distance segments defined by a distance of light travel during one cycle of the frequency, the distance segment spanning between two different distances, wherein a distance between the two light sensors and the surface is between the two different distances, the distance segment selected based at least in part on at least one of:
comparing the first measured value or the second measured value of the intensity of light to baseline light intensity data stored in reference data, the baseline light intensity data being associated with one of the plurality of equal distance segments, orcomparing a variance in at least the ratio and a second ratio to baseline variance data stored in the reference data, the baseline variance data being associated with one of the plurality of equal distance segments; anddetermine the distance between the two light sensors and the surface based at least in part on the ratio and the selected distance segment.