Autonomous Scout Drone...
Drones are offering unprecedented aerial perspectives to amateurs, but their high price and often steep learning curve make them inaccessible to may hobbyist that could be aided by them.
This project is intended to develop a drone to compliment people's current interests and hobbies, while not replacing them. That requires a drone which is reliable, easy to use and can be thrown in an equipment bag, the back seat of a car or quickly tethered to a backpack without a second thought.
The concept is something that has been evolving for several years now, but was born in the high scrubby desert of Arizona as my brother and I struggled to find poorly maintained access trails to cliff and crags we wanted to climb.
Often, a day was lost back-tracking from misleading washes or game trails. However, once the climb was complete, from the top of the cliff the access trail and approach became obvious.
We needed something that ran autonomously, was simple enough to work all the time and inexpensive/tough enough that you could remain focused on something else. Looking at the available drones at the time everything that came close was expensive, needed support equipment and would require another bag or case to haul with you.
Luckily, my brother and I didn't have to wait for our idea to show up, we could leverage our aerospace engineering degrees and skills in 3D design/printing and imbedded electronics to create just the thing we needed.
Configuration & Design...
This scout drone is about having an aerial aide that is always with you. It's compact and convenient and can live its life moving from equipment bag to backseat and back again. Its co-axial rotor design greatly reduces the number of motors and speed controllers needed compared to a quad or multicopter and allows all the mechanical parts to be protected in a central, cylindrical shell.
To further reduce the volume of this drone the rotors spin on a central carbon fiber shaft, which not only provides excellent stiffness, but allows electrical wires to be routed above, below or between the rotors.
While not in flight, the rotor blades of this drone are forced to collapse along its body by torsion springs mounted in the blade's flapping hinges. Once on its mission however, the blades are pulled straight by centripetal force.
When needed, this scout drone is pulled out and a mission selected.Some commonly used missions are preprogrammed, such as a quick pop-up to record video or to orbit at a set radius/altitude around the user. Custom missions can also be created and uploaded via Bluetooth and a mobile app.
Once the mission is selected, the drone is hand launched, accelerating quickly to its predetermined altitude where it can take pictures/video or transmit a text message from a better vantage point than the user.
To descend, power is simply cut to the motors and the drone falls minimizing drift from the wind. As it falls a barometer and GPS track its decent rate and when certain conditions are met, power is restored to the rotors momentarily breaking its fall. Finally, power is once again cut to allow the rotor blades to retract and prepare for a soft impact with the ground. Once retrieved, images and flight data can be downloaded to the mobile app.
Before we could approach anything called a prototype we knew that several concepts needed to be proven out. Could a flying machine of our scale be produced on a desktop 3D printer? Would routing all our cables and wires through a central spine induce too much noise and interference? Would torsion springs in the blade's flapping hinge complicate their dynamics?
Week by week, we would answer a question only to discover two others. This was slow and agonizing progress, but eventually we ran out of questions and soon found ourselves limited by the current design. We were ready for something which closer represented our drone.
Taking what we learned from the Flying Test Stand, it was time to construct our first prototype. We incorporated the full set of sensors (9-axis IMU, GPS, Barometer, Ultrasonic Range Finder) and took a first cut at the general shape.We also needed to compress our electronics and minimize wiring.The goals were to prove outdoor flight, test the accuracy of the GPS, measure ascent rates and exceed 300ft in altitude.
While testing with the prototype continued, several more iterations of the body were constructed. The volume of the drone was reduced, parts simplified and work began on a custom PCB layout . Soon the next generation prototype will be ready for testing....
We're received a lot of interest from friends who encouraged us to blog about our work. After a few posts we have been contacted by people around the world who see a wide range of applications. In future designs we would like to get away from 3D printing and use more robust plastics or composites. The user interface would be greatly improved (currently a couple push buttons and LEDs) to include a mobile app for programing custom missions and downloading data. We would also like to experiment with an IR camera (for identifying people and animals) and add an antenna to assist in cell phone calls or to broadcast text messages while in flight.
This drone with all these features is certainly within grasp of today's technology and we are well down the road of realizing it. However, progress would be much quicker if we could devote ourselves to this program full time, therefore, we are turning to crowd funding to help us get prototypes out, speed progress and fulfill a demand that is certainly out there.
Campaign and Rewards...
We are currently working on how to structure and run the campaign with the goal of launching in the next 3 to 5 weeks. Rewards could include:
- Receiving weekly or bi-weekly progress reports
- 3D print files, materials list (bearings, gears, etc) and assembly instructions
- Receiving early prototypes
- Advanced orders on the final product
Please leave you email address if you are interested in recieving information as we continue to the launch of our crowd funding campaign. If you have questions, comments or suggestions please email us at MeringerAerospace@gmail.com