Position updates faster than 1s or GPS with intertial sensor?

gork · 09-15-2003, 03:11 PM

I have noticed that many commercial navigation systems seem to update position/speed/etc with about a 1/2 second interval, while every receiver I've ever attached to my computer gives about a 1s update interval.

Does anyone know of a receiver that has a faster update frequency or does anyone know of a receiver that provides position updates based on inertial sensors when gps is not available?

MichaelG · 09-15-2003, 03:51 PM

I believe that the Garmin GPS 16A updates 5 times/sec. It is very expensive though, upper $200's. I am new to the GPS arena and doing my research now, but I expect that update time is only usefull if the software can be configured with a similar setting. I am looking at the GPS 16 (WASS, updates 1/sec) because everything I had read from users seems to indicate that it locks faster, AND can be mounted inside a trunk and still get a signal, unlike others. (My other choice would be the DeLorme Earthmate). Anyway, look for information on the Garmin GPS 16A, check their website they had info about it.

gork · 09-15-2003, 04:27 PM

Ah yes knowing about one product has now led me to several good solutions.. Unfortunately they are fairly expensive as you said, but if I can get the application that I want to get working going it won't really be that big of a deal

The Garmin GPS-16A looks like it's actually the cheapest 5Hz unit out there, beating out even some other manufacturer's 2Hz models.. Too bad it doesnt have an amplified antenna I dont think...

fluffy2097 · 09-15-2003, 05:58 PM

What application are you trying to make work with a garmin 16a?

gork · 09-15-2003, 06:06 PM

None yet.

In combination with ODB-II engine logging and a fast-updating GPS (possibly with DGPS or WAAS), I'd like to write an track trainer/logger application that logs car position, throttle position, speed, acceleration, etc. through turns. You could drive a track or an autocross event and easily spot what you did wrong on a turn. This should have some pretty neat training / driver education applications. 1Hz updates, though, are really a bit slow for this, but 5Hz looks a lot better..

Of course, it would also be nice to if it worked with some of the standard GPS apps that people here use like Destinator MapPoint, etc.. I really don't see why an application would care since they generally parse the NMEA streams and update every time they get a new position report.. The 16A output is still NMEA messages even though they are coming every 200ms instead of 1s..

fluffy2097 · 09-15-2003, 08:03 PM

The garmin GPS 16a will probably work for anything you want it to. It's output is configurable, so you can make it send whatever sentences you want it to, as often as you want it to. I've hacked my GPS 35 to work with Travroute copilot and the 16A has the same capabilities.

Alanh · 09-15-2003, 09:30 PM

gork,

The GPS-16 is supposed to be waterproof or water resistant so if the size doesn't bother you, you can put the entire thing outside if you want. Its pretty easy to work with since there isn't any coaxial RF wiring to worry about. With just power and RS-232, its easy if necessary to cut the connector off to run the wire through tight spaces and then wire it back up, or extend the length of the cable.

There are some GPS/inertial sensors out there, but as far as I know, they're all really expensive. I checked on one system that was an add-on inertial system that took a GPS input (user provided as I recall) and it was around $1500 US. Maybe there will be something cheaper in the near future as more people get interested. Of course, most people will probably want the full-blown integrated route planning & nav system whereas I want just the GPS/sensor so I can use a PC with moving-map software for when I'm out where I hope there won't ever be data for automated route planning.

UncoCow · 09-15-2003, 09:44 PM

Quote: Originally Posted by gork

None yet.

In combination with ODB-II engine logging and a fast-updating GPS (possibly with DGPS or WAAS), I'd like to write an track trainer/logger application that logs car position, throttle position, speed, acceleration, etc. through turns. You could drive a track or an autocross event and easily spot what you did wrong on a turn. This should have some pretty neat training / driver education applications. 1Hz updates, though, are really a bit slow for this, but 5Hz looks a lot better..

Of course, it would also be nice to if it worked with some of the standard GPS apps that people here use like Destinator MapPoint, etc.. I really don't see why an application would care since they generally parse the NMEA streams and update every time they get a new position report.. The 16A output is still NMEA messages even though they are coming every 200ms instead of 1s..

y don't you just use a G-Force sensor to map the turns? that's what all commercial systems i've used do, and they are very accurate... and updates instantly, you can even get the G-forces at any point on the lap....

also wouldn't having a whole computer in ur car be bad because of the weight? i guess if you're under the minimum weight...

gork · 09-16-2003, 01:17 AM

Well.. Now I just need to find a cheap Garmin 16A

Anyone know of a good source new or used?

UncoCow:
Inertia-Only systems are fine if you get frequent reference points. In-car 1/4 mile timers and whatnot are good doing this type of thing, but I really was looking for something a little bit more accurate... perhaps using GPS/WAAS for reference points and interpolating with accelerometer sensors.

Weight

I'm not doing this to drive in competition for money or anything. This is for the weekend when I go to the AutoX for fun or do a Car control clinic or something .. would be a really neat teaching car

-TheDarkEye- · 09-16-2003, 03:24 PM

Quote: Originally Posted by UncoCow

y don't you just use a G-Force sensor to map the turns? that's what all commercial systems i've used do, and they are very accurate... and updates instantly, you can even get the G-forces at any point on the lap....

also wouldn't having a whole computer in ur car be bad because of the weight? i guess if you're under the minimum weight...

im sure you mean an accelerometer? =D

Mr24play · 09-16-2003, 10:43 PM

Quote: Originally Posted by fluffy2097

The garmin GPS 16a will probably work for anything you want it to. It's output is configurable, so you can make it send whatever sentences you want it to, as often as you want it to. I've hacked my GPS 35 to work with Travroute copilot and the 16A has the same capabilities.

Mind telling us how you got the garmin to work with cp? I have a gps16

spectrumzz · 09-18-2003, 12:52 AM

Quote: Originally Posted by gork

None yet.

In combination with ODB-II engine logging and a fast-updating GPS (possibly with DGPS or WAAS), I'd like to write an track trainer/logger application that logs car position, throttle position, speed, acceleration, etc. through turns. You could drive a track or an autocross event and easily spot what you did wrong on a turn. This should have some pretty neat training / driver education applications. 1Hz updates, though, are really a bit slow for this, but 5Hz looks a lot better..

Of course, it would also be nice to if it worked with some of the standard GPS apps that people here use like Destinator MapPoint, etc.. I really don't see why an application would care since they generally parse the NMEA streams and update every time they get a new position report.. The 16A output is still NMEA messages even though they are coming every 200ms instead of 1s..

Most GPS systems are only good to 2-5 metres (such as the cheaper Garmin, the Earthmate and Deluo systems), which means that even at an update of once per second, they aren't accurate enough to plot tracks through turns. I am using custom software with my Deluo that updates every time a position comes across the wire, and while fast, the position isn't always quite right. What you are looking for is a very expensive high speed GPS unit.

krystar · 09-18-2003, 01:27 PM

what you're looking for is a military GPS unit

if you really need accuracy and speed, you might want to read up on DGPS. but that'll involve synchronization with your base unit. duno if you wanna get that fancy

wi77iam · 09-18-2003, 07:38 PM

Quote: Originally Posted by spectrumzz

Most GPS systems are only good to 2-5 metres (such as the cheaper Garmin, the Earthmate and Deluo systems), which means that even at an update of once per second, they aren't accurate enough to plot tracks through turns.

The Earthmate is WAAS-enabled. The Deluo is not. WAAS capability improves position accuracy to < 3 meters. WAAS was designed to provide precision aircraft flight guidance, so I would think it is accurate enough to plot a car going around a bend.

Zip-Lock · 09-20-2003, 12:56 AM

Maybe if you bump up the baud rate of your GPS it would help. 4800 baud is standard, so maybe 9600 baud would help.