Hey blog readers!
This week was one of the best yet – testing. With many weeks of work done on the vehicle by the highly skilled Sentry team, Sentry is almost ready to exit its overhaul period and get back to sea. The last step in the overhaul, as is traditionally the last step in any engineering implementation, is testing. Sentry can be tested in a number of ways, but for this testing period it was privy to all of them.
First was deck testing, which is exactly what it sounds like. Out of water, the general functionality of Sentry is tested. This includes engaging thrusters, moving servos, checking battery diagnostics, flashing strobes, beeping acoustic transmitters, and more. This is the first all-vehicle check to ensure that things are working after the extensive take-apart of the vehicle. During this iteration of testing, the team discovered some issues with the response time of the multibeam’s transmitting transducer, or its TX unit. We troubleshooted by changing the TX unit (a heavy–40lb–ceramic red rectangle that houses the necessary components and is bolted to the bottom of the vehicle) out for a spare. To do this, we didn’t actually change anything about the vehicle–a technician simply propped up the spare unit on a wooden block, so that the cable which connected the TX to the rest of the vehicle could reach the spare instead. This is an important bit of experienced/insider knowledge, because often the problem isn’t where you “think” it is, and if you were to actually switch out the whole TX unit and then discover it wasn’t the problem, you would have wasted at least an hour and a lot of nerves! It was discovered that the spare didn’t work either–so likely the issue wasn’t the spare, but really another component. Because the multibeam is a non-critical sensor, although a very important one, the team decided to defer the issue until well testing when more data could be gathered which would help troubleshoot the cause of the issue.
After deck testing–numerous times–comes well testing. Well testing is a lot more explanatory than I initially thought–it is essentially, sticking the robot in a well, and seeing how it does in water. This serves the same purpose as deck testing, as well as checking that all parts have been sealed properly (to prevent leaking of oil, which is annoying at surface but fatal under pressure) and the ability to actually gather data from the sensors and check that they are truly operating properly. Because most of the sensors rely upon acoustic data, and some even rely upon flushing ocean water through themselves, it is important that they are submerged to really understand how they are functioning.
That’s all for this week–hope you enjoyed! I sure did :).
Write you later,
Steph