Data Logging- Anyone With Experience/electronic Knowledge?

[altezzaclub]

I'd like to record a few things like suspension travel in the rally car but have no idea about how to go about it. I could rig up a mechanical system to get maximum compression over a rally stage, but would really like something to record 10 or 15minutes worth of movement.

 

Then it will be G-forces, steering input, pedal movement.. I can see this will never stop!

 

So, if anyone has any ideas on how you record data, store it and display it later I'd like to know. Farmspec of course, I could go and spend a couple of hundred thousand dollars and buy the commercial packages, but I'm sure ingenuity can do it.

 

My kickoff point would be an infra-red distance meter from a robot shop, so it produces a signal of distance, but then what do I do with the signal??

 

http://www.robotgear.com.au/Product.aspx/Details/271-Sharp-IR-Distance-Sensor-GP2Y0A21YK0F-GP2D12-10-80cm

[It's_AUDM_Yo]

Not sure how far your going with this but you could do a setup like in drift bible pretty easy.

Skip too like 19mins

[snot35]

I've thought about this too, but it's way down the list when there isn't a motor in the car that will be logged. I'm thinking along the lines of an arduino and some linear transducers. The transducers need an amp though, you need to get 0-5v range into an arduino, but most of them have analog inputs.

 

Something like an arduino uno has 6 analogue inputs and the knock offs can be had for about $20. There's heaps of tutorials for these things out there, plus plug in boards for SD, g sensors etc, great for datalogging.

 

Something like this: http://www.ebay.com....984.m1423.l2649

 

Could be useful, but for car suspension range you'd need to run two in series.

 

Another thing I was thinking of was using normal pots and something like RC aircraft turning lightweight swing arms attached to the pots so that the fragile stuff could be mounted in the boot/inside the car/under the bonnet, rather than attached to struts etc. where there would be quick death on a rally/khana car.

 

Of course, there's a bit of work in such a project :)

Edited June 7, 2013 by snot35

[altezzaclub]

I can see there is years of work in it! I checked a couple of parts shops, Jaycar, auto electrician, performance shop and none of them had any idea about data-logging at all.

 

Then I went to the library and spent half an hour in the electronics section learning how little I know. I can see that I need a way to measure movement, I was thinking of the infrared distance sensor, but the transducer would do as well. We aren't interested in the whole range, just the compression really.

 

Then that data needs to be recorded, so the sensor must talk to some motherboard that can remember it onto a phone chip or camera card, so we can take it out later and read it on a computer. The data also neeeds to be clocked somehow so we can arrange it against a start time.

 

We will borrow someone's sports camera and run that at the same time so we can see the road and simultaneously see what it does to the suspension.

 

That is the basic model, the next would be to add pedal movement and steering, with a G-meter. The ultimate chassis logging would be directional readings from GPS, so we can tie it all together and see how we can improve understeer/oversteer, traction, handling under braking etc without touching the motor.

[snot35]

There's a huge amount in it. The electronics required is reasonably basic as most if it's made to be modular and easy to start, but it's a huge topic and off the shelf setups are pretty expensive.

 

This is useful: http://farnorthracing.com/datalogging.html

[coln72]

Not so much data logging but I was running against a team that was running car to pit telemetry. Showed track location, speed, battery power (was electric), motor temp. Etc. big jealous! Had our marking off the fuel tank in 500 ml increments and guessing w mch we had used look average

[altezzaclub]

This is useful: http://farnorthracin...atalogging.html

 

haha- that's where it started! I linked that up to someone on here for their handling ideas, and was vaguely reading through his datalogging ideas. That crystallised some thinking I'd been doing about watching the suspension travel with a webcam and I realised there is a lot of data you can gather.

 

So, the logger is around $1000-$2000 for basic stuff, and the sensors might add another $1000. You'd need to make some money back off it somehow. I'll keep at it.

[coln72]

This may be of interest http://www.picaxe.com/docs/axe110.pdf

[philbey]

You could use a megasquirt unit to datalog a bunch of sensors if you wanted.

 

Suspension travel is a cool project, you could use linear potentiometers easily enough but you're probably looking at 200 bucks for a decent one last time I looked. Farnell and RS Components have them.

[snot35]

Yeah, about that last time I looked too. Some of the tech edge widebands have some data logging channels. Could kill two birds with one stone :) None of it is plug and play though. That seems to cost.

[altezzaclub]

$14 for a Sharp infra-red proximity sensor, so a pair of those on the cage above the back axle facing down. Drill a couple of holes in the floor and clamp a bit of #8 wire to the diff, one on each side, up through the holes and put an aluminium foil piedish on each wire. As the wires go up and down with the diff, the sensors record how far away they are.

 

https://www.sparkfun.com/products/242

 

Probably run them under the front mudguards if we can find somewhere safe for them, so they can measure off the front tyre or we'll fit a reflector to the strut. One Arduino board can handle those 4, then another board for G-meter, brake pedal, steering and throttle... and the wife's new camcorder for in-car video..

 

Ah, sounds so easy!! You're right, its not plug & play unless you put up several thousand bucks!

[coln72]

But where's the fun in "plug and play".......

 

[snot35]

I wonder how well those sensors handle dirt and debris breaking the beam and some pretty intense vibrations though.

[altezzaclub]

I know- That's why I figured I'd start with the rear axle and mount them inside the car. Hopefully my Mkll roof vent will keep the inside clean.

 

The ones like a yoyo could be fitted to the front turrets and mounted inside the engine bay with a hole through the turret to a attachment on the strut. As the strut goes up and down the wire goes in and out of the yoyo and gets measured.

[luk3333]

You can buy these: http://www.ebay.com.au/itm/ATMEGA328P-PU-with-Arduino-BOOTLOADER-Socket-16MHz-crystal-Kit-/320949081653?pt=LH_DefaultDomain_15&hash=item4aba0e5635&_uhb=1

and make your own arduino for half the price. Also you could get more than 4 Analog inputs on each arduino by using the PWM digital inputs. They have 256 marks of resolution (not sure of the correct term) compared to the 1024 that the analog inputs have, but 256 would be more than enough for monitoring a few cm's of travel such as a pedal.

 

I'm not sure what you had planned for video capture and storage but you could "hack" the camcorder so that the arduino starts filming when you start the datalogger and stops when you stop it. Then you graph your travel against time and and use the graph as a reference as you watch the video. eg, see the car go over a large bump at 1.26, refer to graph at 1.26 to see how the suspension behaves.