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Mars helicopter employs advanced control techniques to survive in-flight anomaly

210 点作者 dougmany将近 4 年前

14 条评论

njoubert将近 4 年前
I see no mention of &quot;advanced control techniques&quot;? Sounds like there is just a limit on roll&#x2F;pitch angles and a limit on distance applied. Saying &quot;advanced control techniques [for multirotors]&quot; sets an expectation for something along the lines of Tedrake&#x27;s Underactuated Control approaches: <a href="http:&#x2F;&#x2F;underactuated.mit.edu&#x2F;" rel="nofollow">http:&#x2F;&#x2F;underactuated.mit.edu&#x2F;</a>
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rsp1984将近 4 年前
Fusing video with IMU for navigation is called VIN (visual-inertial navigation) or VIO (visual-inertial odometry) and the field has made enormous progress over the last 10-15 years. It&#x27;s the same technology that the iPhone uses for all its AR features.<p>Dropped frames are one of the easiest things to handle. Yes, the visual feature tracking depends on frames of video but even cheap phone IMUs these days are good enough to dead-reckon for a second or two, especially when embedded into a sensor fusion framework, so the prediction errors resulting from a single lost frame should be very minimal and not enough to throw off the tracking.<p>That&#x27;s why I find it hard to believe that the VIN in use by the Mars Helicopter (part of a multi billion dollar program) wouldn&#x27;t be able to deal with a dropped frame. It just doesn&#x27;t add up. I suspect that the situation is much more complex than what the article suggests and that more things went wrong than just a dropped camera frame.
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kklisura将近 4 年前
Here&#x27;s a research paper that might provide more information: &quot;Vision-Based Navigation for the NASA Mars Helicopter&quot; <a href="https:&#x2F;&#x2F;sci-hub.se&#x2F;10.2514&#x2F;6.2019-1411" rel="nofollow">https:&#x2F;&#x2F;sci-hub.se&#x2F;10.2514&#x2F;6.2019-1411</a><p>&gt; This paper provides an overview of the Mars Helicopter navigation system, architecture, sensors, vision processing and state estimation algorithms.
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HALtheWise将近 4 年前
I can&#x27;t think of a polite way to say this, but as someone who professionally develops drone software, both of the software failures experienced by Ingenuity have been embarrassingly amateur at a technical level.<p>The first failure, which delayed the initial spin test, was described as a &quot;watchdog timeout&quot;, which for anyone not familiar with embedded development basically means the code crashed. We all write code that crashes, but I am having trouble thinking of an excuse to justify the fact that their code crashed before takeoff, on Mars, and they didn&#x27;t see it coming. There is nothing about sitting on the ground on Mars that shouldn&#x27;t have been tested repeatedly on earth, and testing in production is _really_ not the right way to do Aerospace development (although Boeing Starliner would beg to differ)<p>Similarly, there are a huge number of things that can and will result in dropped frames when running Linux on a Qualcomm mobile chip, and having a software stack that infers frame timing purely from the sequence number is brittle, and would definitely not have passed code review and testing where I work (I actually checked, we do have a robust solution). If I had to guess, I suspect the root cause of the dropped frame wasn&#x27;t actually anything exciting like a cosmic ray, but instead was some run-of-the-mill event that would have been caught by a couple hours of flight testing on Earth. Either way, it shouldn&#x27;t have made it to Mars.<p>I&#x27;m sure that there are a lot of great engineers working on the Ingenuity project that _don&#x27;t_ write these sorts of bugs, and am glad that theae amateur fuckups (barely) haven&#x27;t crashed the drone before it has been able to do some incredible technology demonstration work.
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ealloc将近 4 年前
The article says the problem was a dropped frame from the camera, but that just further piques my curiosity:<p>Presumably they use some kind of Kalman Filter, but those are easy to program to account for missing frames, or frames at non-discrete timepoints, perhaps even for screwy camera images if the programmer had a reasonable prior for the likelihood of it happening. Kalman Filters by design account for measurement error.
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renewiltord将近 4 年前
NASA systems appear to have the property that they are both perfectly designed when HN commenters do not understand the code and amateurishly designed when they have errors.<p>This bathtub style curve for perception of NASA design by HN commenters makes me question if the perception correlates with reality.
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isatty将近 4 年前
Terrible article - rehashed old news with a new title and even though it’s on “control.com” has no mentions of what said advanced control techniques are. Atleast it has pictures.
jsrcout将近 4 年前
Article from the Mars Helicopter chief pilot: <a href="https:&#x2F;&#x2F;mars.nasa.gov&#x2F;technology&#x2F;helicopter&#x2F;status&#x2F;305&#x2F;surviving-an-in-flight-anomaly-what-happened-on-ingenuitys-sixth-flight&#x2F;" rel="nofollow">https:&#x2F;&#x2F;mars.nasa.gov&#x2F;technology&#x2F;helicopter&#x2F;status&#x2F;305&#x2F;survi...</a>
anticristi将近 4 年前
Time to set up a GPS constellation on Mars? Somehow forgot that this navigation aid -- that we take for granted on Earth -- is missing on this other planet.
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heisenbit将近 4 年前
&gt; the inertial measurement unit (IMU) and the navigational camera. The IMU measures acceleration in three dimensions, using data from several sensors to estimate altitude, velocity, and position. Even though this system samples at 500 Hz, the error would accumulate over time, causing the helicopter to become lost quickly.<p>I understand the IMU is not an ideal input and integration over time leads to positional errors. But gyros are much better and the orientation of the drone in flight is paramount. What I wonder is what ‚advanced‘ control law allowed the drone to become unstable wrt. orientation when there was noisy positional input.
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jollybean将近 4 年前
Can anyone hint why they wouldn&#x27;t use a gyro?<p>When it&#x27;s on land, they can make the gyro reliably point &#x27;down&#x27;. Then at least during flight they know which way &#x27;down&#x27; is.<p>Would this be too fragile for Mars?
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iancarroll将近 4 年前
It’s cool to see how they compensated for the IMU inaccuracy. I bought an IMU off of Amazon once and tried to use it to measure the position of a steering wheel. This worked for one rotation, but as it mentions, it’s incredibly hard to compensate for the error margin — as you integrate more measurements, the error builds up irreconcilably to the point where it’s a useless instrument.<p>I am sure the one on the Mars helicopter had more precision though :)
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dougmany将近 4 年前
After five successful flights, the Mars Helicopter had a minor incident during its sixth voyage that was fixed using advanced control systems.
ncmncm将近 4 年前
The control system is clearly designed wrong. Navigation input should not be able to affect the closed-loop control system directly. It should affect only the calibration, incrementally. If that had been done, there would have been no flight instability, just disagreement between the IMU and navigation about how far they had flown.<p>There are certainly people involved in the project who could have explained this to them. I hope they are learning fast.
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