Multiple motors or servos are the norm for drones to achieve controllable flight, but a team from MARS LAB HKU was able to a 360° lidar scanning drone with full control on just a single motor and no additional actuators. Video after the break.
The key to controllable flight is the swashplateless propeller design that we’ve seen a few times, but it always required a second propeller to counteract self-rotation. In this case, the team was able to make that self-rotation work so that they could achieve 360° scanning with a single fixed LIDAR sensor. Self-rotation still needs to be slowed, so this was done with four stationary vanes. The single rotor also means better efficiency compared to a multi-rotor with similar propeller disk area.
The LIDAR comprises a full 50% of the drone’s weight and provides a conical FOV out to a range of 450m. All processing happens onboard the drone, with point cloud data being processed by a LIDAR-inertial odometry framework. This allows the drone to track and plan its flight path while also building a 3D map of an unknown environment. This means it would be extremely useful for indoor or underground environments where GPS or other positioning systems are not available.
All the design files and code for the drone are up on GitHub, and most of the electronic components are off-the-shelf. This means you can build your own, and the expensive lidar sensor is not required to get it flying. This seems like a great platform for further experimentation, and getting usable video from a normal camera would be an interesting challenge.
I assume I missed something – if the drone only has a single motor, how does it control its horizontal movement? Does it have more than one motor or is it doing something clever like maybe increasing thrust when it is facing the direction it wants to move in?
I think that’s kinda how this design works? If I remember prior designs using it right it modulates the power cycle of the rotors themselves to tweak the direction they’re facing using those slanted hinges. Similar to a swashplate, but just with in-cycle motor control.
Described explicitly around the 1-minute point in the video.
Just like a traditional helicopter, it controls the pitch of the props when they are on one side to cause the craft to tilt slightly and move horizontally. Normally this is done with a swashplate, but this project uses angled hinges on the props like this https://youtu.be/d80oXSCcHTk?si=R22ALcWCy4BSkMXU. When the motor torque is increased, the pitch on one prop increases and decreases on the other. By timing the motor torque perfectly, the entire craft can tilt in any direction.
https://www.youtube.com/watch?v=aEPf0QHVuMM
10 years ago this guy came with this way of controlling drones
Sounds amazing but kinda over engineered like wheel design…
My favorite version of this – if only for the assonance – (from 1989) was the “Samara Camera”, proposed as an unpowered probe modeled after spinning maple seeds. In terms of simplicity (and given modern IMU units to help re-assemble the image) it still seems like an interesting idea.
https://ntrs.nasa.gov/citations/19890000054
Hm, to get usable video out of it I’d imagine one would have to sync the drones rate of rotation to the cameras frame rate.
Could probably be fine tuned to provide a camera feed for any direction at will. Then one could sync the control inputs to the direction the feed is transmitting and make it an FPV drone.
So cool. I haven’t seen that not-a-swashplate in a while. Last I saw it wasn’t so efficient, now we’re hovering a 1.2kg bot with a single motor! I wonder how this would work with other expensive sensors like FLIR