Next on the Horizon: LiDAR UAV without GPS
At the recent ILMF Conference in Denver, the high level of interest in UAVs (unmanned aerial vehicles) continued as several new systems were introduced. One of the intriguing products demonstrated at the show was an Octocopter UAV carrying a Velodyne HDL-32E LiDAR sensor weighing only about 2 pounds. Designed by XactMaps, the Octocopter is a remote controlled aircraft capable of carrying a variety of sensors, including LiDAR, video, multispectral, infrared, and thermal. It conveniently folds up and fits in a rifle case for transport.
Andy Trench, owner of XactMaps, flew the Octocopter inside the conference hall in front of a crowd while collecting real-time LiDAR data. Trench is developing software that can process low-altitude aerial LiDAR data without having GPS onboard the UAV. He describes this process as an early example of what could be a streamlined way to conduct mapping and surveying.
“The fact that I do not have GPS onboard this mapping UAV is a proof-of-concept for a smarter software approach to accomplish what has always been done with IMU and GPS,” explained Trench. “We are using the LiDAR data itself to perform the localization of the aircraft, allowing the data to be stitched together into a complete model of the subject. For more accurate large-area mapping, ground control points and onboard RTK GPS can be added to the workflow to geo-reference the data, but it shouldn’t be necessary for smaller scans and architecture. To provide RTK GPS, we have been testing a new, affordable, and very small GPS soon to hit the market.”
The Velodyne sensor technology has proven itself in road and terrain mapping and many robotic applications used in autonomous road vehicles and military vehicles. Over the past twelve years, Velodyne has concentrated on reducing the size and weight of its sensors while improving performance. The underlying software being developed by XactMaps will make it feasible for small UAV (less than 55 pounds) to carry high-performing sensors without needing additional locating equipment. It is expected that small UAV will be allowed to conduct commercial operations sooner than large UAV due to safety concerns, so size and weight is very important to the geospatial community.
The Velodyne 32e uses 32 individual lasers spread in a 40 degree vertical pattern, allowing for a more “3D” view of the environment. In contrast to a single line scanner, the subject is measured from many angles as the mobile platform passes across its surface, resulting in less shadow and a higher density of data with more of the surface being measured. Also, by flying at a lower altitude, the scanner is exposed to the sides and lower parts of a structure rather than just the roof. The maximum speed of movement and the tolerances to the frequency of the aircraft’s attitude and movements are all important factors yet to be tested. Trench’s concept requires flying at a lower altitude at a slower speed, which he believes delivers a more thorough result.
“XactMaps is approaching the problem from a different perspective by building proprietary software to create highly accurate maps from any type of sensor data without onboard GPS,” said Trench. “In some instances, GPS is extremely unreliable, and has even been proven to be subject to hacking and tricked with false information, so we are trying to reduce that risk.”
XactMaps builds custom UAV and associated software to support the broad range of sensors and applications available today. The next version of the Octocopter is being designed to carry a multi-sensor gimbal. By integrating many sensors on a single platform, more industries can make use of the emerging small UAV technology.
“I believe we are in the very early stages of innovation in this field, and I intend to remain at the bleeding edge of that progress,” said Trench. “With the recent court victory in favor of legal UAV use in the US, I’m optimistic about the future development of UAVs. If we don’t embrace this new industry, we will fall behind the rest of the world and lose an opportunity to regain our momentum as a technology leader.”
XactMaps will be in Booth #1405 at the AUVSI Unmanned Systems 2014 show in May in Orlando, where it will be prepared to discuss new aircraft designs that offer longer flight times, custom sensor mounting options, and enhanced safety features.