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Makani source code released

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Re: Makani source code released

#101

Post by arbitel »

rubicon33 wrote: post #76

Incredibly ambitious project. I watched the whole documentary. I'm surprised they were 'unable to secure additional funding'. Considering how many crackpot app-of-the-month companies have gotten cash thrown at them over the last decade, you would think a company doing real engineering would be drowning in money. It's a bummer to hear that they folded. Speculation abounds, I suppose, as to why investors started (or ke…

When investors look to invest, they want a fast ROI. Engineering company likes this typically takes many years to fruition or maybe not. It's much easier to justify dumping money on these "tech" companies like WeWork, AirBnb hoping to get another facebook unicorn than putting money into real engineering company like Makani.

Re: Makani source code released

#102

Post by ntucker86 »

brandmeyer wrote: post #13
msoad wrote: post #8

Why this failed? I would love to learn more if anyone has more insider knowledge

The tether replaces one set of problems with a different set of problems. Some of the new problems had promising solutions, but others were more marginal. 1) Land use. The small props are loud, and the setbacks relative to populated areas are pretty high for tether and crash safety. Solution: offshore. Now you have two problems :) 2) The tether's weight is a factor. Its hard to build in much margin on this component…

The tether was indeed medium voltage, but the motors and controllers were not, through use of a fairly novel stacked architecture.

There were still hard problems to solve there, but ultimately the power system worked well, and out performed it's original design targets. It was not responsible for the projects demise.

Re: Makani source code released

#103

Post by desdiv »

londons_explore wrote: post #91
krisoft wrote: post #81

Earlier quoted context omitted.

The FAA (or your local alternative) might want to check your paperwork and licensing too.

While it stays tethered to the ground, I don't believe the FAA would be interested? Am I mistaken?

A tethered unmanned aircraft is still considered an aircraft by the FAA and subject to FAA regulations:

https://plane-lyspoken.foxrothschild.com/2017/12/03/tethered...

Re: Makani source code released

#104

Post by ntucker86 »

tobinfricke wrote: post #45
hlandau wrote: post #10

Any chance on board schematics, or even just some basic block diagram of the avionics hardware? It's hard to understand this firmware without having any idea what it ran on.

Ask away and I'll tell you what I can. :-) You'll find some description here (but no schematics): https://storage.googleapis.com/x-prod.appspot.com/files/Maka...

the system overview slides in... part II?

pretty sure there is a top level avionics layout in there.

Re: Makani source code released

#105

Post by tonyhb »

tobinfricke wrote: post #41
msoad wrote: post #8

Why this failed? I would love to learn more if anyone has more insider knowledge

> Why this failed? Well, I think the main TLDR is that it would require significant additional investment to reach MVP. Also- the energy sector lacks the huge margins of the tech sector. Renewables have long been subject to a boom-bust cycle driven by the prevailing price of energy. Our released technical report "The Energy Kite" is intended to help answer this question, and to explain what we would do if we had the…

Clean small scale rapid deployment power generation sounds like such a good thing for emerging countries! :sob-emoji:

But then again, so does solar. It's tough to compete when there are existing options.

Full respect to everything you and your team built!

Re: Makani source code released

#106

Post by tonyhb »

winrid wrote: post #33

Some of the code for the tools is fun to read https://github.com/google/makani/blob/c421e4497dd09c86b01725... This is not proper Java, at all. But it's what a lot of Java code looks like because it's a good choice for inexperienced devs or rushed projects.

The commenting here is actually pretty dope. I really enjoy the small notes saying _why_ the code exists:

    // because all low speed wind tunnel cases are overset and all high speed are 
    // fixed with a remesh, we only rotate in the presence of overset domains.
This is something that personally I strive to do but isn't always repeated in my team. It's important as 6 months later you struggle to remember the nuance that lead to your code being written.

Whoever this is seems to have experience with this, so I definitely wouldn't say this is an inexperienced dev.

Re: Makani source code released

#107

Post by mdorazio »

pas wrote: post #94
nikitaga wrote: post #74

Earlier quoted context omitted.

X is still X and Google is still Google. Outside of X, Google was never known for crazy moonshots. Google was always an ad platform with a search engine.

Gmail seemed kind of crazy at the time.

The only crazy part when it launched was the growing storage space aspect, which only seemed crazy because all the other mail providers were so ridiculously stingy. Email as a fantastic data gathering and ad platform made sense from day one.

Re: Makani source code released

#108

Post by sjburt »

meekrohprocess wrote: post #35
elromulous wrote: post #27

Earlier quoted context omitted.

Not entirely true. The actual autopilot (the controller + estimator) runs on an imx6. The tms570 are the sensor / actuator nodes. Edit: just to add some detail. The autopilot and aio (avionics io, i.e. the tmd570s) communicate over a ring ethernet topology.

Oh, that makes sense. It did seem like a lot for such a small processor to handle. Still, that sounds even cooler; a reference for how to set up a local network of MCUs controlled by a big processor? Awesome.

This topology is very common. Hard real-time sensor nodes feeding softer real-time big iron that does the estimation and control.

Re: Makani source code released

#109

Post by tobinfricke »

londons_explore wrote: post #91
krisoft wrote: post #81

Earlier quoted context omitted.

The FAA (or your local alternative) might want to check your paperwork and licensing too.

While it stays tethered to the ground, I don't believe the FAA would be interested? Am I mistaken?

Makani engaged early with FAA and we had a great working relationship. This enabled us to move out of China Lake (where we were using the military's restricted airspace, which didn't require FAA approval) and out into the public airspace in Hawaii. We did several test flights in close collaboration with FAA observers, developing a color scheme for the tether and a lighting system for the kite and ground station that were deemed adequately conspicuous. We also held a round-table with local pilots to get their input. Ultimately we operated under a "determination of no hazard" that classified the Makani system as an obstruction, something like a large radio tower.

Our COO gave a talk on the FAA approval process at the Airborne Wind Energy Conference (AWEC) a few years ago: https://repository.tudelft.nl/islandora/object/uuid:ea8256a2...

Re: Makani source code released

#110

Post by tobinfricke »

sleavey wrote: post #73
elromulous wrote: post #26

Former Makanite, and current abc employee here. Happy to answer questions.

What sort of control methodologies were you using for the autopilot? Classic linear negative feedback or more modern techniques? How much of the autopilot problem was novel? Could you use existing designs from other aircraft or do these tend to be kept secret?

The top-level autopilot used a nonlinear path controller, which produced position, attitude, and rate commands for an inner-loop controller that used linear feedback and gains computed using LQR and a linearized model of the system.

Because the maneuver the kite must fly is very dynamic (always turning, but not at constant rates), control with feedback alone would lead to pretty sloppy flight, since feedback requires an error to develop before the system can respond to it. Good feed-forward was crucial to flying well; from the desired flight path, wind speed/direction, and desired aerodynamic quantities (airspeed, angle of attack, and angle of sideslip), we could compute the required rates and feed-forward actuator displacements needed to execute the trajectory.

For more details, check out my paper titled "The Makani Autopilot: A Critical Retrospective", available here: https://storage.googleapis.com/x-prod.appspot.com/files/Maka...

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