Constructing a cheap timing system?

[ChemicalChaos]

Hi all,

I'm helping to construct a cheap lap timing system for a formula student team car. Currently the car has an RFID tag like this on the chassis, for clocking it into and out of events:
http://www.atlasrfidstore.com/Omni_ID_Max_Rigid_RF...

The team leader has suggested using it as the basis for a lap timing system, but I am quite sceptical as I know that RFID is very short range, and doubt the tag would register on some timing gates during a high speed pass several ft away.
My current idea is a traditional hillclimb style light gate, using something like a laser pen and a detector set up to be broken by a convenient bit of the roll hoop on the car. However, I have reservations about this idea too, as I know they are hard to align and get working properly even on a costly professional system.

Has anyone else got any other ideas?

[Munter]

Depends on accuracy required.

Could you use a GPS app?
http://www.gps-laptimer.de/Home.html

[Graham]

Ibeacons maybe? They are bluetooth low energy but have a much bigger range than rfid

I assume you need to build sonething as its fs.

I might be able to donate a beacon
G

[itdontgo]

You'll need an active RFID type tag. I designed an active RFID access control system based on a PIC16F639 which will work with big enough LF aerials. Look the chip up so see what I'm on about.

Race car transponders are effectively the same design requiring a power source. Bloody expensive though; I bought a TSL MyLaps transponder yesterday for £360!

[ChemicalChaos]

Hi chaps,

Thanks for all the recommendations. A colleague and I have gone through and looked at passive RFID, active RFID, laser gates, kart transponders, and VBox/AiM/Racelogic systems.
We loved the features of the advanced GPS systems and their ability to plot g force traces, racing line comparisons etc etc. However, the cost is way out of our league! Thus, we were blown away by that mobile phone app!!! Only 20 quid for everything a VBox does and a while lot more! We are going to get a cheap android phone to install in the car and run the software on, that way we will be able to compare everyone's driving styles.
The real kicker is the app's ability to talk to OBD ports, so we can also make throttle and brake traces

[andylaurence]

Are you sure you have OBD on a Formula Student car? They're normally 450-550cc air-cooled singles or 600cc 4 bangers from motorbikes. Bikes don't tend to have OBD. My GSXR engine has a TTL serial output for the dash. Have you considered a RaceCapture/Pro? About £250 but has 3D accelerometers, yaw sensor and a variety of inputs and outputs you can use. It's got on-board scripting, so you could potentially hook it up to your paddleshift and run an automatic shifting algorithm. There's a live telemetry option too, so you can use it during the endurance to monitor car performance, not to mention posting live data, which is good for PR/media. There's a prize for the best PR/media from Racecar Engineering - last year was an afetrnoon in the MIRA wind tunnel...

[Nefarious]

ChemicalChaos said:

We were blown away by that mobile phone app!!! Only 20 quid for everything a VBox does and a while lot more! We are going to get a cheap android phone to install in the car and run the software on, that way we will be able to compare everyone's driving styles.
The real kicker is the app's ability to talk to OBD ports, so we can also make throttle and brake traces

I went down this road last year, using HLT on an iPhone. It's all fantastic in theory, but the reality is the the 1Hz sampling rate is woefully inadequate, and the resulant interpolation means that the data gathered list little more than guessing masquerading as proper measurement. Good for pub bragging, but little more.
I ended up adding a VBox Sport to the set-up (with a 20Hz sampling rate), which means you get all the fancy stuff of HLT without the inaccurancy. Comparing with the old iPhone system, some of the speed readings were 20% out!!
I'm sure you student types are a lot more savvy than me, but don't expect all the Bluetooth/OBD stuff to be plug-and-play. You will need somebody who's pretty handy on the software side of things to get that to work, and even then it can be a bit flacky.

[andylaurence]

Nefarious said:

I went down this road last year, using HLT on an iPhone. It's all fantastic in theory, but the reality is the the 1Hz sampling rate is woefully inadequate, and the resulant interpolation means that the data gathered list little more than guessing masquerading as proper measurement. Good for pub bragging, but little more.

I used to use a phone-based solution when I did AutoSolo, which is very similar to a Formula Student sprint/endurance track. With internal GPS, it's useless. You absolutely have to have an external GPS device of 5Hz or more, at which point it becomes usable at a basic level. I used to have a QStarz BT-818X 5Hz receiver, but they now do the XT, which logs at 10Hz. Of course, that's about £100, plus the £50 tablet/phone to run the software and, by that point, you're half way to getting a proper logger.

[Stevemcmaster]

Having gone through the adoption of HLT for this very reason in the past month - a couple of things I have picked up along the way:

- There is a greater range of external External Bluetooth GPS Receivers if you are using android.
- However, the HLT for Android is not as fully developed as for IOS. There is an update due at end of March that will take Android to the same level as IOS petrolhead version.
- IOS GP edition has experimental integration with Go Pro Hero 3 cameras allowing the camera to stream its video to the IOS device and be overlayed with the GPS/OBD data if you have it.

Other BT/Android GPS lap timer options is Trackmaster.

Either way, as one of the other posters said - VBox levels of functionality for £8/£12/£24 quid depending on the version + a GPS receiver if you want greater GPS accuracy.

Thanks
Steve