Sensing on UAVs for mapping and obstacle avoidance
Structured light approaches utilize a laser to project features, which are then captured with a camera. By knowing the disparity between the laser emitter and the camera, the system can triangulate to find the range. Four, 185 degree field-of-view cameras provide overlapping views over nearly the whole unit sphere. The cameras are separated from each other to provide parallax. A near-infrared laser projection unit sends light out into the environment, which is reflected and viewed by the cameras. The laser projection system will create vertical lines, while the cameras will be displaced from each other horizontally. This relative shift of the lines, as viewed by different cameras, enables the lines to be triangulated in 3D space. At each point in time, a vertical stripe of the world will be triangulated. Over time, the laser line will be rotated over all yaw angles to provide full a 360 degree range.
1. A low-light environment obstacle avoidance-enabled UAV, comprising:
a plurality of fisheye cameras displaced from each other horizontally, each camera comprising a wide-angle compound lens;
a plurality of near-infrared laser projection line scanners displaced to simultaneously project a plurality of vertical laser lines in an environment surrounding the UAV, thereby generating vertical line light pattern projections, each laser projection line scanner comprising a solid-state laser diode and an aspheric collimation lens coupled in front of a laser emitter and that splits a laser beam emitted from the emitter into upward and downward vertical line portions;
a UAV rotation mechanism operable to alter a yaw orientation of the plurality of near-infrared laser projection line scanners; and
a microprocessor in communication with the plurality of fisheye cameras, the plurality of near-infrared laser projection line scanners, and the UAV rotation mechanism, the microprocessor being configured to:
(i) operate the UAV rotation mechanism to alter a first yaw orientation of the plurality of near-infrared laser projection line scanners at a first point in time to a second yaw orientation of the plurality of near-infrared laser projection line scanners at a second point in time,
(ii) process images captured by the plurality of fisheye cameras to: (a) triangulate, at the first point in time and based on first identified locations of first vertical line light pattern projections from the near-infrared laser projection line scanners a first plurality of point locations in a 3-D space comprising the environment surrounding the UAV, and
(b) triangulate, at the second point in time and based on second identified locations of second vertical line light pattern projections from the near-infrared laser projection line scanners a second plurality of point locations in the 3-D space comprising the environment surrounding the UAV, thereby defining a point cloud, and
(iii) conduct, based on the point cloud, an obstacle avoidance navigation of the UAV.
2. The low-light environment obstacle avoidance-enabled UAV of claim 1 , wherein the downward vertical line portion of the laser beam creates a laser line that extends from horizontal to negative 80 degrees pitch.
3. The low-light environment obstacle avoidance-enabled UAV of claim 1 , wherein the upward vertical line portion of the laser beam creates a laser line that extends from horizontal to positive 80 degrees pitch.
4. The low-light environment obstacle avoidance-enabled UAV of claim 1 , wherein each camera comprises a spectral filter.
5. The low-light environment obstacle avoidance-enabled UAV of claim 1 , wherein each camera comprises an optical bandpass filter.
6. The low-light environment obstacle avoidance-enabled UAV of claim 1 , wherein the vertical laser lines are projected along a vertical sensor plane and wherein the vertical sensor plane is aligned with a direction of travel of the UAV.