Electro Gyro-Cator | Hacker News Reader

Electro Gyro-Cator

en.wikipedia.org

101 pointsgumby57 comments

Another early inertial navigation system for cars was the Etak Navigator, which was originally released in 1985. The idea for the device was conceived onboard Nolan Bushnell's racing yacht in a conversation between Nolan and his navigator, Stan Honey. Stan, who was also an accomplished engineer, went on to found Etak with Nolan's financial backing. You can see the device in Chevy Chase's car early on in the 1991 film Nothing But Trouble.

1. https://www.fastcompany.com/3047828/who-needs-gps-the-forgot...

Worked on early auto navigation systems at Motorola in the early-90s, using differential wheel sensor data from the ABS system for dead-reckoning interpolation between fixes from the original SA-active GPS before the full constellation was deployed. This was a hard problem to solve with the technology of that era, and impossible at an economically viable price point. Our map database was on an original Red Book single-speed CD qualified for automotive temperature range. It took minutes to plan a route.

Sometimes the technology just isn't ready.

This has to be the closest to a joke-name that a real product has. I read "Electro Gyrocator" but I hear "Turbo Encabulator"

And the UI has that beautifully complex vibe that's the opposite of flat. Every atom of it is very touchy-feely.

More importantly, every component is differently touchy feely, so that it can be easily used by touch alone.

...without forcing the user to look at what is touching to know what is touching and in which state it is (kinaesthetic communication)

Looks like it had a base plate of pre-famulated amulite surmounted by a malleable logarithmic casing...I can see why it was so expensive!

Gotta get that side-fumbling under control!

Wasn't there another turn-by-turn system of similar vintage which worked similarly and was surprisingly accurate, because it used turns as checkpoints to null the error and reset where it was?

I want to say it was an American system.

There was an older system that used a cassette tape which told you to make a turn when the odometer reached a certain distance: https://jalopnik.com/this-cassette-tape-based-navigation-sys...

Do you mean this?: https://arstechnica.com/cars/2020/01/turn-by-turntables-how-...

It showed up on HN some time ago.

Maybe Etak? https://www.fastcompany.com/3047828/who-needs-gps-the-forgot...

Bingo

Electro Gyro-Cator (1981) - https://news.ycombinator.com/item?id=10614058 - Nov 2015 (6 comments)

A video showing the device in action: https://www.youtube.com/watch?v=hOqig8rixOU

Wow. I imagine there was quite a bit of drift.

Probably not, as it was only optioned to the Accord and Vigor, which are FWD vehicles.

http://instantrimshot.com/

Even with data from all four wheels the system as it is described cannot prevent drift altogether. Wheel diameter is variable depending on many factors, tires can lose grip on the road, and also the earth is not perfectly flat. There would be other sources of inaccuracies, but basically in any real-world situation you need some kind of absolute position source to get drift-free location data. The trick is that it can be very noisy and low bandwidth if you integrate it with other sources of data like and IMU.

The comment you replied to was an attempt at a joke

I know explaining a joke ruins it but I failed to understand it so far.

They are intentionally misinterpreting "drift" as the driving technique (often associated with RWD vehicles) rather than the intended meaning.

"Drift" is another term for understeer which is when the rear-end of the car loses traction in a turn. It tends to be easier to induce (accidentally or on purpose) in a rear-wheel-drive car.

I should note that my ~2005 MY Ford Focus would absolutely understeer if you enter a turn too fast without applying power.

Are you lifting right before you start to turn in? That'll do it, because lifting off the throttle abruptly will shift weight to the front, which will unweight the rear; and sometimes that little weight transfer is all it takes to break the back end out a bit. (Used to do this regularly in a Taurus that I had the pleasure of driving for a few months.)

Yeah, the first gen focus is pretty easy to induce lift-off oversteer in. The rear end weighs nothing and the suspension sits strangely high.

> Lift-off oversteer

was on the tip of my tongue. Thank you!

Oversteer is when the rear end loses traction. Understeer is when the front end loses traction.

holy shit I wrote it exactly backwards. I didn't have my coffee this morning.

This thread just keeps drifting further and further away from the original topic.

The device is described as using a gyroscope to measure movement, so it would be independent of wheel diameter and grip. Gyroscopes still drift, so occasional calibration against an absolute position source is still required.

The device uses a gyroscope to determine direction. But a gyroscope is unable to measure distance travelled. So this device also attaches to the transmission to determine distance.

> A special servo gear was also attached to the transmission housing to feed information to the Gyro-Cator to help maintain position, map speed and distance traveled.

You could compensate for drift if you use a map as a constraint on the position.

Well, I thought it was funny.

Handbrake!!!

Don't change the subject; we are talking about cars, not video encoding!

You can drift with anything that has wheels, or even, tracks, somebody did that.

And drifting with FWD german family car is one of my favorite activities.

Yep - 3.5% of distance traveled (i.e. drive 1 km and you'd have 35 meters of drift)

That's not that bad, specially for solo driving where you cannot use a regular road map (remember those?).

Let me guess: you didn't ever solo drive for work. You can certainly use a paper map while driving. When it gets too distracting to safely drive then you are lost and should stop and use the paper map more thoroughly to find out where you are.

Source: I intentionally tried to be a parcel delivery driver without a GPS-based navigation and only with regular road map and printed out rough plan of the route. Not to mention that for most of my long driving trips I used to simply print out the itinerary from RAC RoutePlanner and ignore the navigation (it is a shame that this service apparently does not exist anymore).

Not bad.

When you consider a city block is about 100m, you could drive 3km before being off by a street so as to miss your turn.

On the highway it’s even better- if exits are 5km apart, you can drive 142km before being so far off you might miss your exit

That is surprisingly close to what I used as a good-enough error in fallback route estimator in our TSP/VRP solver. I came up with that essentially by curve-fitting great-circle WGS84 distances and really traveled distances between my favorite pubs and it seems to work (bear in mind that it is the last fallback and there is A* on map data and ML-ish thing before that)

Everything is fractal/self-similar

Yes. I found this paper which measured the errors of the system: https://apps.dtic.mil/sti/pdfs/ADA138283.pdf

They performed two kind of measurements. On a bench they measured the drift of the helium-flow gyroscope in itself, and then they took the whole system to drive test loops and measured the errors in eastings and northings.

Quite a thorough job in fact, but I guess that is what you get if you ask a rocket scientist to evaluate a new-fangled vehicle navigation tool.

...this place is so weird, I love it so much.

Like if there was going to be one place where a random comment links to an actual Defense Technical Information Center technical report evaluating the system, it's here.

Then you may find even more happiness on Reddit where you can find specialists about everything

I'll bet HNers have a collection of fascinating subreddits.

HN is better - it's broader and there's usually amazing takes in the comments (amazing good, not YouTube "amazingly WTF" style comments)

Thanks for the link to the paper, this was an insane amount of work.

It doesn't say in the article, but I'm pretty sure you drop in a slide with the map on it, and then you move the pointer to your current location. So you reset the drift every time you use it.

Depends on the qualities of the gyros. My step-dad flew 707's between NY and London, and INS on those used the same kind of system (obviously more pro version) - one of the reasons it was no longer necessary to carry a navigator in the cockpit.

IIRC some pre-GPS cold-war era spy-planes used an INS that was corrected for error with an analog-computer celestial navigation system.

Meanwhile my 2022 smartphone sometimes decides it's going the opposite way down the road because its dash mount is pointed at the driver instead of straight at the back seat.

Or decides that after an hour of travel on the highway, at highway speeds, my car shifted 15 meters to the side and I'm actrually doing double the speed limit on the frontage road. No, wait, I'm on the highway. Oh nope my bad, actually on the frontage road.

So true. Oh wait, I took that exit. No wait I didn't. No wait, I'm back on the entrance ramp!

I'm pretty sure a lot of military submarines use inertial navigation.

I think a lot of military craft do. I know for certain a lot of jets do, and I think tanks do as well. Unsure outside of that.

It's also being used in aerospace & naval navigation. Interestingly, the more advanced systems use fibre-optic gyroscopes, see https://en.wikipedia.org/wiki/Fibre-optic_gyroscope.

Northtrop Grumman manufactures those, for example.

That seems really the only option; but how do they account for currents? Or do they match the sensor data with the engine output to correct for this?

Interesting thought experiment. I'm gonna say currents don't affect the accuracy of either a gyro or an accelerometer.

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