Methods and systems for obstacle detection using structured light

An obstacle detector for a mobile robot, the detector comprising:

• at least one light source configured to project light in a path of the robot wherein light projected in the path of the robot has structure, and
• wherein the light source is pulsed in a determined sequence;
• a visual sensor for capturing a plurality of images comprising reflections of the projected light, wherein at least a portion of the plurality of images are captured by the visual sensor while the robot is in motion;
• a processing unit for detecting reflections, wherein the processing unit is configured to:
• generate at least two difference images from a first plurality of image pairs, a given image pair in the first plurality of images pairs comprising a first image captured with the at least one light source on and a second image captured with the at least one light source off;
• and
• mathematically generate at least one filtered image to suppress movement artifacts, based at least in part on at least two difference images generated from respective pairs of images captured by the visual sensor;
• compare pixels of the at least one filtered image to a threshold value to detect reflections from the light source;
• a tilt sensor, included in the robot, configured to sense a tilt of the robot caused by a floor surface over which wheels of the robot are traversing;
• wherein the tilt sensor included in the robot is configured to determine an orientation of the robot with respect to at least the floor surface the wheels of robot are traversing;
• and
• an obstacle detection unit configured to detect an object in the filtered image and determine whether the object is an obstacle or is the surface the robot is traversing based on the detected reflections from the at least one filtered image, wherein the obstacle detection unit is configured to apply tilt compensation with respect to one or more images, comprising one or more images of reflected light, based at least in part on information from the tilt sensor to facilitate determination as to whether the object is an obstacle or is the surface the robot is traversing.