Boomerang 60 mid-air launch development and Hex HereFlow optical flow testing

By | August 15, 2019

This week we moved from the Hobbyking Bixler 2 as a launch platform for our HolyBro QAV250 Quadcopter onto a bigger platform, a Boomerang 60. The Boomerang is a conventional ‘pull’ configuration training aircraft, compared to the ‘pusher’ electric-glider configuration of the Bixler. We made this transition because we think the Boomerang is more representative of the type of airframe we will use for the support aircraft in the 2020 Medical Rescue UAV Challenge. We learned a lot in this short and unsuccessful mission! We had underestimated the effect that  the propeller in front of the QuadCopter would have, as you can see clearly from the video. Back to the drawing board for the mounting system!

We also tested the new Hex HereFlow combined optical flow and LIDAR unit over CAN on another of our HolyBro QAV250 QuadCopters. In the 2020 Medical Rescue UAV Challenge we intend to drop the QuadCopter near Joe’s shed then navigate it into the shed to achieve video and audio communications with Joe. To do that we need to be able to navigate the QuadCopter precisely from outside the shed into and then inside the shed. We found that the LIDAR struggled to maintain accurate height in the bright Australian sunshine, which  is likely to be a problem in the challenge. We found that the combined sensors of the HereFlow worked quite well in the shade outside. As you can see from the video, the QuadCopter maintained a decent 1 metre circle in reasonable wind without GPS data, but maintenance of the set altitude was still a little erratic. The performance in the shed was better again, as you can see on the video. Our test validated the manufacturer’s known limitation that the LIDAR doesn’t work over two metres altitude. Our tests indicated that it has limitations in high illumination levels too, but we didn’t do enough testing or have a light meter to properly quantify this. Overall the HereFlow seems like a promising tool but we need to augment it with a better LIDAR rangefinder. We’re planning to use a Lighware LW20, so watch this space!