It’s been more than a few hours since our last check-in, and quite a bit has happened, actually.
First off, allow us to say that we are sorry about the absence of videos. We promised some cool footage earlier, but we’re facing some technical difficulties and haven’t had to time to get around them. As far as we’re concerned, watching the vehicle fly is one of the coolest parts about the project, and it’s a minor tragedy that you guys don’t get the chance to see that. Once we get things figured out we’ll get those out there for you guys.
Now, onto more interesting business. We have been testing all day and are at a bit of a cross-roads. Earlier in the day we embarked upon the exciting challenges of end-to-end competition testing. In doing this we also embarked upon the much less exciting and far more frustrating world of end-to-end competition problems. This is to be expected with any system, and things are still going well, but there are problems in the system that have to be addressed. Some of the problems could potentially be alleviated with new hardware and so testing has begun. We are fortunate enough to have 15 people here right now, so work has been divvied up and multiple avenues are currently being explored.
One of the things we are considering is stepping up from a 3 cell LiPo battery to a 4 cell LiPo. Doing this would increase the voltage of our system, which would in turn increase the maximum force output of our motors. The thought here is that we would have more control authority of our vehicle, and we would be able to maintain a more stable flight. One problem that we have here is that increasing the voltage of our system would actually change the calibration of our motors. Put simply, increasing voltage means that we would not know exactly what force our motors are outputting anymore. The problem is easily fixed by measuring the RPMs that the motors when given a specific command from the computer. Unfortunately, we do not have a tachometer (which is the device you would use to do this). So, the obvious fix here, is to make our own. I’m sorry if all of that sounds complicated, the take-away is that we don’t know how fast our motors are spinning, and to figure it out we had to build our own measurement device.
With a little bit of work we successfully calibrated the motors with 4 cell batteries, and made it a viable option.
Another thing that could help us is to switch to more powerful motors. We still have an air frame from last year’s competition, which is outfitted with new motors. The circuit board has changed since then, but it is a pretty straightforward process to switch to the new board. We put some of our electrical engineering wizards on the job and are about ready to fly on the old frame.
We are not completely certain that these are changes we want to make, though, so we also have to make sure that the old system is still functional. Part of this is repairing the vehicle when it crashes, which, by the way, it did earlier. This isn’t a huge deal, really just more of a minor headache. We were testing inside the test course (did you see the panorama of that by the way? It’s pretty cool), the vehicle strayed a bit to close to a wall, and we lost control. To avoid injury to ourselves and the vehicle Joe and José pulled ropes and the vehicle casually struck the table on its way down. None of our sensors were damaged, but we did crack an arm. This is a really common failure so the structures team had no problem applying the routine fix. The vehicle was reassembled and has since been flight tested (it still works!).
Our competition flights will be beginning in approximately 10 hours so it’s going to be a late night, but things are going well and we’re keeping our chins held high.
We don’t expect you all to stay up all night with us, but we’ll continue updating for all of our insomniac followers.