As our Critical Design Review (CDR) approaches, the airframe team is beginning the process of testing the mechanical components of the system. Specifically, we are looking into testing the docking joints, the carbon fiber spars, the target mounts, and the payload mount.
The docking joints will undergo testing for both performance and durability. Our objectives are to identify the amount of alignment error we can afford during docking and how much stress the docking mechanism can withstand. To get a more thorough understanding of how much alignment error we can afford, we will be taking a statistical approach to analyzing our results, meaning that we are looking for a success rate for each of our different test conditions.
Our carbon fiber spars will be treated as a cantilever beam. We will be attempting to apply a load at one end of the spar that is about the same as the max thrust exerted by one of the hexacopters.
Our objective with regards to the target mount it to figure out if it is rigid enough to ensure AprilTag detection during flight. We will try to simulate the flight conditions by using a wind-making device.
Finally, we want to test the payload mount and container to make sure that there is no significant movement during flight that could affect flight dynamics by changing the center of gravity or by inducing oscillations. We will test this by taking and comparing accelerometer readings from the payload and the payload’s container.
This week the team had a meeting with one of our alumni and discussed testings for different parts of the system and integration. He provided many useful insights regarding the degree of tests that we should perform before putting all of the components together given his expertise in this field. A lot of the discussions focused on making the tests more automated and rigorous so that we can better prepare for more unexpected situations in physical tests. The test-driven development he proposed was not only useful in our current stage of development but also for future projects.
For the incoming CDR, each team has planned a series of tests that would demonstrate the capabilities of individual systems. The controls team will show that the leader drone is able to send commands to the follower drones. The docking team will use on-board Raspberry Pi and camera to guide the drone to autonomously find and land on the target. The Comms team will demonstrate direct and multi-hop inter-drone communication ability and network performance of the OONF framework. Each team is actively designing tests and performing them to get each part of the system ready for integration.
With our Critical Design Review coming in 2 weeks' time, we'll be taking a short break from blogs. Our next one will come after the CDR on the 19th, to give us more time to focus on testing. Look out for an update the following week on how our testing and CDR presentation went!
These results are based upon work supported by the NASA Aeronautics Research Mission Directorate under award number 80NSSC20K1452. This material is based upon a proposal tentatively selected by NASA for a grant award of $10,811, subject to successful crowdfunding. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of NASA.