GPS for acceleration timing.

[DixieTGS]

This is what i get pasting those coordinates in to google maps with the minus sign removed from the 2nd number. It looks very plausible.

 

[decrep]

That looks like poor reception. Is the Draggy close to the windscreen?

 

[vincpa]

The draggy was outside the car near the windscreen and in the middle.

Bingo DixieTGS, that's where it was.

 

[decrep]

hmm. the tracks over the skid pan look right, but the other track that looks like a left foot looks very wrong. That's the one that worries me, something there is out.
Something like that sort of error can occur when unit is first turned on and it hasn't got a proper fix. We normally turn our units on and leave them stationary several minutes before sailing. A good fix can take up to 5 mins sometimes

 

[vincpa]

Sorry guys, I'm hoping you can help me with something else. Thanks for the GPS stuff so far, but I need to somehow work out the drift angle around the track. Is this even possible?

The output file from draggy has heading which I think is the direction the car is pointing. Then using the GPS coordinates I can work out the direction the car is sliding. I'm thinking I can then get the angle the car is drifting. So if the car is drifting north but pointing NE the angle I think would be 45 degrees.

The attached file maps onto this exact lap Vid – Google Drive

 

[mg4mc]

Heading will the direction the GPS is travelling, not where the car is pointing.

 

[DixieTGS]

If you were building your own device as described by @decrep earlier in this thread it would be feasible to add with a bit of extra soldering and some programming so probably not a viable solution for most.

I did a quick search for a phone app to record the magnetometer (magnetic compass) data and gyro data available on most phones but didn't find anything - only direction of travel which you already have. Either of those values may be useful to get what you want.

Maybe suggest it to Dragy to add to their units in the future? It's a motorsports related feature and would only cost a few dollars in parts per unit.

 

[vincpa]

Yeah I might request it to be added by Draggy.

So you gave me an idea, a phone can get GPS and heading via the built in compass. Is this feasible to have an app built or is there not enough resolution?

 

[DixieTGS]

The short answer: I don't know - I have no experience of programming phones.

Longer answer: I suspect you would need the gps time, position, speed data from the dragy because I believe it's more than one set of data per second and the speed calculations especially would be far better than the phone. Then you would need gps time, compass data and / or gyro data from the phone to merge in with it.

But mostly what you need is someone who has done phone programming before who can give a more reliable answer! If you find one and use Android they might want to just modify the "basic air data" gps logger app. It's free and open source.

 

[vincpa]

Awesome, thanks for your time, much appreciated.

 

[decrep]

There are ublox chips that include compass data, but it's another 2 pins on the chip. I'd look at remote controlled aircraft sites, like drones. they make use of this data, to control position and where the camera is pointing.
I think drone software could give you what you want.

I also discovered yesterday that "carscan" can output the car's gps data, but I don't have the software to see if that includes compass bearing.
Or hang on I do, the U-Center app will replay all the data on the file. But I need to boot into a windows computer to play it. I'll have a look after I've done the dishes.
Keep your fingers crossed, this could be your answer.

BTW, we don't trust phone GPS data, they only use very small antennas, and can give strange results. Whereas the car GPS data is very good.

EDIT, but don't get your hopes up, I've just realised, as there's an extra two pins on the chip, it probably isn't a u-blox output, but goes to a second processor. I'll find out later

EDIT EDIT.
Sorry, no orientation info in the ubx file, hope you have luck with the flight controllers.

 

[vincpa]

Right now drift competitions are decided by judges, which isn't very accurate but I'll see what I can find with all the info you've given me.

Cheers

 

[decrep]

Here's webpage, with what I was talking about, if that's any use to anybody.

Beitian BN-220 GPS / BN-880 GPS & Compass — Copter documentation

ardupilot.org