2,800 RPM Spin a Success, however Flight 14 Delayed to Post Conjunction
It’s been an eventful a number of Martian days, or sols, given that our last article, so we wished to supply everybody with an upgrade on where things base on Mars In our last post, we discussed that we were preparing yourself to start flying with a greater rotor speed to make up for reducing climatic density triggered by seasonal modifications onMars Increasing the rotor speed is a considerable modification to how we have actually been flying so far, so we wished to gain ground thoroughly. Step one was to carry out a high-speed spin test at 2,800 rpm on the ground and, if whatever worked out, step 2 was to carry out a short-duration flight, briefly hovering over our present place, with a 2,700 rpm rotor speed.
The high-speed spin test was finished effectively on September 15, 2021 at 23: 29 PDT, 11: 11 LMST regional Mars time (Sol 204 of the Perseverance objective). Ingenuity’s motors spun the rotors approximately 2,800 rpm, briefly held that speed, and after that spun the rotors pull back to a stop, all precisely as sequenced for the test. All other subsystems carried out perfectly. Of specific interest was identifying whether the greater rotor speeds trigger resonances (vibrations) in Ingenuity’s structure. Resonances are a typical obstacle in aerial rotorcraft and can trigger issues with noticing and control, and can likewise result in mechanical damage. Fortunately, the information from this most current high-speed spin revealed no resonances at the greater rotor rpm’s. The effective high-speed spin was an interesting accomplishment for Ingenuity and provided us the thumbs-up to continue to a test flight with a 2,700 rpm rotor speed.
Ingenuity’s Upper Swashplate Assembly: The upper swashplate of NASA’s Ingenuity Mars Helicopter manages the pitch of the upper rotor blades as they turn and is important to steady, regulated flight. The swashplate is driven by 3 little servo motors. Credit: NASA/JPL-Caltech
The test flight was arranged to occur on September 18, 2021 (Sol 206) and was expected to be a short hover flight at 16 feet (5 meters) elevation with a 2,700 rpm rotor speed. It ended up being an uneventful flight, since Ingenuity chose to not remove. Here’s what took place: Ingenuity identified an abnormality in 2 of the little flight-control servo motors (or just “servos”) throughout its automated pre-flight checkout and did precisely what it was expected to do: It canceled the flight.
Ingenuity manages its position and orientation throughout flight by changing the pitch of each of the 4 rotor blades as they spin around the mast. Blade pitch is changed through a swashplate system, which is activated by servos. Each rotor has its own individually managed swashplate, and each swashplate is activated by 3 servos, so Ingenuity has 6 servos in overall. The servo motors are much smaller sized than the motors that spin the rotors, however they do a remarkable quantity of work and are important to steady, regulated flight. Because of their urgency, Ingenuity carries out an automatic look at the servos prior to every flight. This self-test drives the 6 servos through a series of actions over their series of movement and validates that they reach their commanded positions after each action. We passionately describe the Ingenuity servo self-test as the “servo wiggle.”
The information from the anomalous pre-flight servo wiggle reveals that 2 of the upper rotor swashplate servos– servos 1 and 2– started to oscillate with an amplitude of roughly 1 degree about their commanded positions simply after the 2nd action of the series. Ingenuity’s software application identified this oscillation and quickly canceled the self-test and flight.
Our group is still checking out the abnormality. To collect more information, we had Ingenuity carry out extra servo wiggle tests throughout the previous week, with one wiggle test on September 21, 2021 (Sol 209) and one on September 23, 2021 (Sol 211). Both of the wiggle trial run effectively, so the concern isn’t totally repeatable.
One theory for what’s taking place is that moving parts in the servo transmissions and swashplate linkages are starting to reveal some wear now that Ingenuity has actually flown well over two times as lots of flights as initially prepared (13 finished versus 5 prepared). Wear in these moving parts would trigger increased clearances and increased looseness, and might discuss servo oscillation. Another theory is that the high-speed spin test left the upper rotor at a position that loads servos 1 and 2 in a special, oscillation-inducing manner in which we have not experienced prior to. We have a variety of tools readily available for resolving the abnormality and we’re positive that we’ll surpass it and back to flying once again quickly.
Our group will have a couple of weeks of time to finish our analysis since Mars will remain in solar combination up until mid-October, and we will not be uplinking any command series to Ingenuity throughout that time. Conjunction is an unique duration in which Mars moves behind the Sun (as seen from Earth), making interactions with spacecraft on Mars undependable. Ingenuity will not be entirely idle throughout this time, nevertheless; Ingenuity and Perseverance will be set up to keep each other business by interacting approximately when a week, with Ingenuity sending out standard system health info to its base station onPerseverance We will get this information on Earth when we come out of combination, and will find out how Ingenuity carries out over a prolonged duration of relative lack of exercise onMars See you on the other side of combination!
Written by Jaakko Karras, Ingenuity Mars Helicopter Deputy Operations Lead at NASA‘s Jet Propulsion Laboratory
