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

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

#61

Post by dieortin »

x86_64Ubuntu wrote: post #60
fermuch wrote: post #53

Earlier quoted context omitted.

It might be related to the hostility of the environment. The chips aren't radiation proof, so it is expected to have some bit flops due to radiation.

Why on earth wouldn't they use rad-proofed chips on a planet closer to the sun, with virtually no atmosphere compared to earth?

Because it’s a vital part of the mission, using off the shelf components in Mars...

Of course they use rad-proofed chips in the rover. But using a newer Qualcomm processor instead of an ancient chip was a big part of the idea.

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

#62

Post by craftinator »

usepgp wrote: post #43
ghaff wrote: post #36

Earlier quoted context omitted.

>(I think I'm supposed to bang rocks together to make fire, right?) Won't work very well unless you have flint specifically :-) Even if you know the techniques, starting fire without any manufactured tools or manufactured tools to make the devices is really really hard.

Its possible to just spin a dry stick against another dry stick with your hands. takes < 5 minutes to get a fire going.

I'd invite you to watch the show Alone, where many survival experts have had to give up in the first day or two because they opted not to bring a fire steel and don't want to freeze.

You're right that it's possible, but how long it takes, and whether or not you can do it, are dependent on skill and environment. Wrong kind of wood? Screwed. Been raining for a day? Screwed. Sometimes this can be overcome, but you have to know what you're doing, and it can still take hours to generate enough heat to dry the wood until it's possible to friction combust it. Try it sometime, just bring a lighter with you.

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

#63

Post by dieortin »

iancarroll wrote: post #4

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. I am sure the one on the Mars hel…

I might be wrong, but I think the data from the accelerometers would be enough to know the position of the steering wheel without any accumulating error. Of course, the gyro data can be incorporated to improve the system.

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

#64

Post by [deleted] »

caconym_ wrote: post #42
baybal2 wrote: post #34

Earlier quoted context omitted.

> Sensor fusion that incorporates visual information is outside of the typical classical controls sphere and is likely considered part of an advanced controls segment of the devices firmware as opposed to the bog standard deterministic controls algorithm. Not so advanced as very correctly pointed out by https://news.ycombinator.com/item?id=27554949 Motor-attitude control loop cannot, and should not be "fused" with na…

Do any of these commenters have experience designing small "helicopter" "drone" avionics systems using off-the-shelf hardware, as in Ingenuity? For instance, you mention "aerospace grade" inertial sensors, yet Ingenuity apparently uses COTS components in that role^[1]. There are smart people on HN, but unless they have actual professional experience designing similar vehicles, I'm inclined to give the JPL folks the b…

[deleted]

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

#65

Post by ghaff »

craftinator wrote: post #62
usepgp wrote: post #43

Earlier quoted context omitted.

Its possible to just spin a dry stick against another dry stick with your hands. takes < 5 minutes to get a fire going.

I'd invite you to watch the show Alone, where many survival experts have had to give up in the first day or two because they opted not to bring a fire steel and don't want to freeze. You're right that it's possible, but how long it takes, and whether or not you can do it, are dependent on skill and environment. Wrong kind of wood? Screwed. Been raining for a day? Screwed. Sometimes this can be overcome, but you have…

A fire steel is probably the simplest low-tech way to start a fire. You still need some expertise like finding a mouse nest or other flammable material even if it's been reasonably dry.

But friction methods are tough, even if you have a well-made spindle and fireboard--which of course require tools. You're not easily creating those without tools to make those tools. And, even then, it's not super easy especially in a non-optimum environment.

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

#66

Post by AnimalMuppet »

x86_64Ubuntu wrote: post #60
fermuch wrote: post #53

Earlier quoted context omitted.

It might be related to the hostility of the environment. The chips aren't radiation proof, so it is expected to have some bit flops due to radiation.

Why on earth wouldn't they use rad-proofed chips on a planet closer to the sun, with virtually no atmosphere compared to earth?

Um, it's not closer to the sun...

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

#67

Post by creatornator »

the8472 wrote: post #21
anvandare wrote: post #6

Earlier quoted context omitted.

Pretty sure SpaceX's first deliveries to Mars (orbit) will include just that. I think they could probably use Starlink satellites without much modification (most important one I can think of would be more panels to cope with the reduced solar irradiance)? The GPS constellation has 32 satellites. A GPS satellite weighs ~2000kg. Starship should get 100-150 tons to Mars - the math checks out! (Disclosure: I got all my r…

> satellites without much modification (most important one I can think of would be more panels to cope with the reduced solar irradiance)? atomic clocks

This got me interested so I brushed off my notes from grad school--GPS predecessors like the US Navy's Timation first used quartz oscillators, then graduated to atomic clocks in orbit. However, even now ground station atomic clocks issue periodic time corrections to satellites in orbit. Since we can get accurate time of flight to Mars, I imagine satellites without atomic clocks could be used, albeit with less stable pseudo-range estimates. This could be overcome by using more satellites, giving more favorable pseudo-range variances.

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

#68

Post by mikepurvis »

ehsankia wrote: post #56
ncmncm wrote: post #55

Earlier quoted context omitted.

It means that the people who know most about closed-loop vehicle control were not involved in the design of the copter. Such fragility is a really elementary design mistake any experienced engineer would not make. Certainly the vehicle that delivered the lander would not suffer from the same mistake. My interpretion is that the copter, as an inessential system component, was seen as an opportunity for junior people t…

The article makes it sound like after the missed frame, every subsequent frame had the wrong timestamp and was processed wrong, so it sounds like more of a bug. If the subsequent timestamps had the right timestamps, and the calculation was based on delta timestamps, then it would basically basically interpolate over the missing frame and then recover. The fact that every subsequent frame was assumed to be 33ms in the…

And that being a system boundary thing, it’s easy to imagine it as an integration issue, where the controls side maybe assumed it would get a dummy frame or something.

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

#69

Post by latchkey »

HALtheWise wrote: post #49

I can'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. The first failure, which delayed the initial spin test, was described as a "watchdog timeout", which for anyone not familiar with embedded development basically means the code crashed. We all write code that…

It is sad that Skydio wasn't more involved with helping in the creation of Ingenuity.

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

#70

Post by squarefoot »

JoeAltmaier wrote: post #13
anticristi wrote: post #3

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.

GPS doesn't have to be satellites. It can simply be beacons on the ground. Often used terrestrially to get a few more decimal points on a fix.

They could use UWB positioning systems. Accuracy is still not the best, but power consumption is very low and range more than adequate for a small base camp like the landing area. Solar power alone should be enough to power each beacon during Mars' daytime.

https://www.firaconsortium.org/discover/how-uwb-works

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