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H.P. Hovercraft
Jan 12, 2004

there's a world that we know nothing about, that we can only imagine... and that is the world of books

Slippery Tilde

Low-Pass Filter posted:

We've played with Terrastar subscriptions and can get about 20cm with motion with a single receiver and L1/L2. RTK gps can easily get under 10cm with person level movement; this is how surveyors lay out roads and stuff accurately. Still need somewhat expensive L1/L2/L5 antennas tho.

what if you're moving next to a tall building or underneath some trees how much does that affect the accuracy

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Combat Theory
Jul 16, 2017



If I remember correctly all GPS based navigation systems for mobile applications blend the GPS feed with inertial navigation for continuous tracking, but LPF is clearly the authority on the matter.

Shaggar
Apr 26, 2006



Nap Ghost

COMPAGNIE TOMMY posted:

oh yes, I see cyclists "combining" cycling with public transportation by clogging the diamond lane and preventing the bus from passing/moving faster than a bike in first gear

thats the top speed of the bus anyway cause its gotta stop in 10 feet

KOTEX GOD OF BLOOD
Jul 7, 2012



Fallen Rib

Captain Foo posted:

driving sucks rear end and i wish i didn't have to do it so much

evil_bunnY posted:

Driving outside of spirited twisty roads or a track loving blows, my dude


Combat Theory posted:

A cool and good position

iospace posted:

My dude, have you heard of bicycles and public transit? You can even combine the two!

trap sprung

CRIP EATIN BREAD
Jun 24, 2002

Hey stop worrying bout my acting bitch, and worry about your WACK ass music. In the mean time... Eat a hot bowl of Dicks! Ice T

Soiled Meat

Combat Theory posted:

If I remember correctly all GPS based navigation systems for mobile applications blend the GPS feed with inertial navigation for continuous tracking, but LPF is clearly the authority on the matter.

yeah without dead reckoning gps sucks for navigation.

hobbesmaster
Jan 28, 2008


Combat Theory posted:

If I remember correctly all GPS based navigation systems for mobile applications blend the GPS feed with inertial navigation for continuous tracking, but LPF is clearly the authority on the matter.

phones at least also use cell towers and other information. https://en.wikipedia.org/wiki/Assisted_GPS

Dixie Cretin Seaman
Jan 22, 2008

all hat and one catte


Hot Rope Guy

these ideas are too complicated just use a self-driving horse. strap it into AR blinders that show a picture of a carrot along the chosen route. give away the system for free and make a killing with subscription horse poop removal services. recycle the poop into bricks for sustainable concrete. bam ill take my VC money now

Truga
May 4, 2014


Lipstick Apathy

jet airliers use a highly complicated system of gyros, inertia tracking, magnetic compass and probably other poo poo I forgot about for navigation and they'll still drift a few dozen miles per flight, so inertial navigation would be kinda pointless for cars where the difference of 1m is the difference between road and ditch.

Shame Boy
Mar 2, 2010

THE HORROR
THE HORROR



Truga posted:

jet airliers use a highly complicated system of gyros, inertia tracking, magnetic compass and probably other poo poo I forgot about for navigation and they'll still drift a few dozen miles per flight, so inertial navigation would be kinda pointless for cars where the difference of 1m is the difference between road and ditch.

i mean airliners are also going much faster and dealing with stuff like turbulence, and the error is cumulative over distance so the difference between going 1000 miles and going 10 miles is pretty significant, but regardless putting an IMU in a car is still probably pointless

hobbesmaster
Jan 28, 2008


Shame Boy posted:

i mean airliners are also going much faster and dealing with stuff like turbulence, and the error is cumulative over distance so the difference between going 1000 miles and going 10 miles is pretty significant, but regardless putting an IMU in a car is still probably pointless

those also cost about what an entire car does

Combat Theory
Jul 16, 2017



Shame Boy posted:

i mean airliners are also going much faster and dealing with stuff like turbulence, and the error is cumulative over distance so the difference between going 1000 miles and going 10 miles is pretty significant, but regardless putting an IMU in a car is still probably pointless

I mean we gotta diffentiate a bit here. Every car with an electronic stability program already has a full 2 or 3 axis IMU on board, it's just some orders of magnitude cheaper and less accurate than what's used for long range inertial navigation. So has every Tom Tom or other windscreen Navi.

Our Uni wants to Lauch a self driving car competition next year, I'll keep an eye on it but I expect little apart of hot air from it, given that the general attitude seems to be "we have no idea about self driving cars which is good because it means we won't get gated into common thinking approaches"

I hear a little Elon fanboy fapping in the distant corner of the campus.

Combat Theory fucked around with this message at Feb 4, 2019 around 19:48

hobbesmaster
Jan 28, 2008


Combat Theory posted:

I mean we gotta diffentiate a bit here. Every car with an electronic stability program already has a full 2 or 3 axis IMU on board, it's just some orders of magnitude cheaper and less accurate than what's used for long range inertial navigation. So has every Tom Tom or other windscreen Navi.

"some" is doing a lot of work for this, a good laser ring gyro that is part of an imu system is $30k. a good automotive grade one is $5 from digikey which probably means $2 direct https://www.digikey.com/product-det...68-2-ND/5402876

Combat Theory
Jul 16, 2017



I have read about laser ring gyros and I think my abstraction ability has reached its limits for the time being.

evil_bunnY
Apr 2, 2003



Shame Boy posted:

huh ok, though i thought surveyors like, tended to stay in one place when actually taking a measurement
There's a bunch of cool poo poo you can do with drones, machine vision, local GPS station etc

Endless Mike
Aug 13, 2003

Get running
Start pumping your bunions, I'm coming
I'm the dumbest, who flamethrow your function to Funyons
Flame your crew quicker than Trump fucks his youngest
Now face the flame fuckers your fame and fate's done with


just have a fire truck drive where you want to go in front of you, duh

evil_bunnY
Apr 2, 2003



Combat Theory posted:

I have read about laser ring gyros and I think my abstraction ability has reached its limits for the time being.

hobbesmaster
Jan 28, 2008


pretty much every fancy laser measurement thing is "lasers are coherent light so you can measure minute changes to its properties and know its due to some outside factor"

so like, changes in a speckle pattern can be used to measure bloodflow or measure depth or all sorts of other stuff depending on what you build

the main problem is that you're usually looking for minute changes so that means $$$$ for the optics

PleasureKevin
Jan 2, 2011




should Musk be going on (what I assume is) some youtube meme show? is he even allowed by his sitters to do dumb stunts like this after the weed thing and every other thing?

necrotic
Aug 1, 2005
I owe my brother big time for this!

he keeps yes men around so yeah he's going to do whatever he wants.

BobHoward
Feb 13, 2012

The only thing white people deserve is a bullet to their empty skull


hobbesmaster posted:

pretty much every fancy laser measurement thing is "lasers are coherent light so you can measure minute changes to its properties and know its due to some outside factor"

so like, changes in a speckle pattern can be used to measure bloodflow or measure depth or all sorts of other stuff depending on what you build

see: fiber Bragg grating sensors. they’re really cool and can be used to measure an astonishing number of physical things you wouldn’t expect

Main Paineframe
Oct 27, 2010

just can't seem to shoo away that Schumer

PleasureKevin posted:

should Musk be going on (what I assume is) some youtube meme show? is he even allowed by his sitters to do dumb stunts like this after the weed thing and every other thing?

(he claims that) he gets to decide whether or not something gets run by his sitters, iirc

KoRMaK
Jul 31, 2012

Easter was an Inside Job


Shaggar posted:

thats the top speed of the bus anyway cause its gotta stop in 10 feet
Lol good one

Sagebrush
Feb 26, 2012





Gravy Boat 2k

Shame Boy posted:

i mean airliners are also going much faster and dealing with stuff like turbulence, and the error is cumulative over distance so the difference between going 1000 miles and going 10 miles is pretty significant, but regardless putting an IMU in a car is still probably pointless

love 2 spend 20 minutes parked in the driveway spinning up the gyros and aligning my inertial platforms every time i wanna go for a drive

Jabor
Jul 16, 2010

#1 Loser at SpaceChem

same but getting pork gyros and aligning them with my mouth

Low-Pass Filter
Aug 12, 2007


Shame Boy posted:

huh ok, though i thought surveyors like, tended to stay in one place when actually taking a measurement

Well, the RTK base station does stay in one place and has to converge for like 20-30 minutes. Then the rover (i.e. surveyor guy with rod) can move around p much all he wants. If you're trying to locate, say, all the points on a foundation, or locate a water boundary, you're going to collect a lot of points, and you're not going to occupy them for very long. You can just walk up with the rover and hit "collect," no real need to wait around.

If you're close enough to a COORS station, and are able to log raw carrier phase info, you can post process and get sub meter accuracy, but thats, uh, not very useful for a car.

The equipment for this is like 10-20k tho.

Low-Pass Filter fucked around with this message at Feb 5, 2019 around 00:58

hobbesmaster
Jan 28, 2008


Sagebrush posted:

love 2 spend 20 minutes parked in the driveway spinning up the gyros and aligning my inertial platforms every time i wanna go for a drive

remember autonomous cars will always be on and roaming the street looking for fares

Low-Pass Filter
Aug 12, 2007


H.P. Hovercraft posted:

what if you're moving next to a tall building or underneath some trees how much does that affect the accuracy

We never flew any UAV's under tree canopy or near tall buildings lol, so I can't give solid numbers. I'll ask my ex-surveyor co-worker if I can get some numbers.

Theres two components in this environment that affect the accuracy. One is Multipath, where the valid GPS signal is reflected multiple times off of surfaces (tree canopy, buildings) before arriving at the receiver. Since a receiver is calculating time of flight for the signal, this will add error. Good receivers have tricks to reject multipathed signals, and good antennas can also help lower their effect, but they're not magic.

The other is straight up blocking of reception. GPS antennas are line of sight, and if they can't see the sky they can't get solid positions. If you're in an urban canyon, you can still see some slice of sky, and if you can lock onto 4 satellites, you can still calculate position, but you'll have a poor Horizontal Dilution of Precision. Survey grade stuff will just throw out any readings with a poor PDOP or VDOP.

For like a commodity car GPS? probably take you from +/- 5 meters to +/- 30 or more, if you can even get a lock. Cell phone AGPS can help a lot in these situations.

H.P. Hovercraft
Jan 12, 2004

there's a world that we know nothing about, that we can only imagine... and that is the world of books

Slippery Tilde

Low-Pass Filter posted:

Well, the RTK base station does stay in one place and has to converge for like 20-30 minutes. Then the rover (i.e. surveyor guy with rod) can move around p much all he wants. If you're trying to locate, say, all the points on a foundation, or locate a water boundary, you're going to collect a lot of points, and you're not going to occupy them for very long.

If you're close enough to a COORS station, and are able to log raw carrier phase info, you can post process and get sub meter accuracy, but thats, uh, not very useful for a car.

The equipment for this is like 10-20k tho.

also surveyors are typically looking for elevation, not just horizontal data, which by how the system works requires more accuracy, so if you only care about your lat/long or northing/easting you can do it faster

though the last time i had to go out and shoot points the station was running some kinda lovely windows xp mobile version that i spent more time wrestling with than it actually took to just calc each point

Low-Pass Filter
Aug 12, 2007


ya total station software is realllll bad.

ol qwerty bastard
Dec 13, 2005

If you want something done, do it yourself!

Sagebrush posted:

love 2 spend 20 minutes parked in the driveway spinning up the gyros and aligning my inertial platforms every time i wanna go for a drive

i mean honestly if this process involved flicking rows of manual switches as indicator lights came on and you could hear stuff audibly spooling up i'd be totally down with it, that'd be rad

Sagebrush
Feb 26, 2012





Gravy Boat 2k

Get a pilot's license. Even the little tiny planes are gonna have at least one or two gyroscopic instruments and you can indeed hear them spinning up and down

ambient oatmeal
Jun 23, 2012



Tesla's gonna add "Hyperdrive Autopilot" where they just play the sounds of gyros spinning and relays clicking so you think you're driving the millennium falcon

hobbesmaster
Jan 28, 2008


Sagebrush posted:

Get a pilot's license. Even the little tiny planes are gonna have at least one or two gyroscopic instruments and you can indeed hear them spinning up and down

I wonder if we can get fishmech to argue a DG is a compass

Feisty-Cadaver
Jun 1, 2000
The worms crawl in,
The worms crawl out.

Muscles Boxcar

hobbesmaster posted:

I wonder if we can get fishmech to argue

yeeeeeeeeep

Captain Foo
May 11, 2004

the cyberpunk dystopia is now
you are not the runner


Clever Betty

Sagebrush posted:

Get a pilot's license.

lmfao no

President Beep
Apr 29, 2009


Grahms ah dint fell so gud!


hobbesmaster posted:

I wonder if we can get fishmech to argue a DG is a compass

your taking us down a very dark path rn.

Chris Knight
Jun 5, 2002

And I'm only saying this because I care.

There are a lot of decaffeinated brands on the market today that are just as tasty as the real thing.



Fun Shoe

Jabor posted:

same but getting pork gyros and aligning them with my mouth

year of the pig brah!

Schadenboner
Aug 15, 2011




Sagebrush
Feb 26, 2012





Gravy Boat 2k

lol le random

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Schadenboner
Aug 15, 2011



Sagebrush posted:

lol le random

But that’s not a horse and it isn’t eating broccoli?

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