What to do when you've got better data?

[poppopbangbang]

I've just had a letter through from the local police informing me that one of our cars has been recorded by a civilian volunteer speed awareness group exceeding the posted speed limit, specifically 39mph in a 30mph zone. No action to be taken but it will be recorded potentialy for future use.

The car is a development vehicle and as such has a pretty extensive telemetry and data suite onboard, the bits which are important with regards the above being:

- Twin redundant 20hz GPS recievers
- None contacting optical speed over ground sensor
- Redundant wheel speed sensors, diff speed sensor and gearbox input shaft speed sensor
- TPMS which is accurate enough to account for the differences in rolling radius of the tyre due to thermal changes.

And it logs all that in a time stamped form with position data. From that I can see that car in question was on that road on that day and the maximum speed it achieved was 28.7mph as an average from all four wheel speed sensors, this figure is backed up by the ratio calculation based on diff speed and again by the calculation based on gearbox input shaft speed. The GPS agree with it to +/- 0.05mph.

I really want to write back, present our data and request that the do gooders involved are trained properly and evidence of this is provided to avoid future incorrect recordings. Or shall I just screw their letter up and chuck it in the bin?

[poppopbangbang]

balls-out said:

WOW - I would have guessed these are TINY. So what sort of difference do thermal changes make - sounds like something I HAVE to know - Surely such knowledge will impressed my friends.... (err not that I have many of course - I wonder why).

Depends mainly on the tyres construction but what you see from the increase in pressure as the tyre heats is an increase in rolling radius. On a run flat (low profile, mega stiff sidewall) its almost none existent, on an F1 tyre its massive. With accurate enough wheel speed information and gearbox input shaft speed information you can plot what difference is present across a tyre pressure/temperature range. For super accurate tyre temp we'll use three IR pyros in the arch and an ambient air temperature sensor inside the wheel.

[poppopbangbang]

I'll write them a letter this afternoon :-)

[poppopbangbang]

andycaca said:

something to do with keeping old F1 cars alive and running i think, based on previous posts in the F1 forum (and my dodgy memory)

That's one part of the business, the other is that we use the same technology, skill set, procedures and experience to assist OEM manufacturers with development of new products, road cars, race cars etc. Essentially if you have enough people and kit of sufficent quality and ability to run a few year old F1 car you're quite useful for many other motorsport/performance road car things as well. Hence we get involved in a lot of proto/dev/test stuff.

[poppopbangbang]

So, ignoring the somewhat OTT escalation on this thread, just to keep you all informed I've arranged a meeting with the Chief Inspector of our local area to have a chat regarding this and some other matters. I'll report back on what the repsonse is - I thought this was a much better way of doing it than simply banging a letter our which could potentially be seen as having a bit of a whinge, or the value of the data in it ignored by the admin department.

To be clear I'm not going at this with an eye for causing trouble or giving them a hard time. I really do think there is a serious issue here with the methods employed especially if this data is being recorded and kept!

Will keep you all informed.