Some more information needed:
Range in G (or how long to 70MPH)?
Resolution?
Sample rate?
Size / weight limits (if its a significant proportion of total mass it will affect performance)?
Recording time (see first question)

Robert.

I was at the library today and saw an issue (within the past year) of Make magazine that used a Raspberry Pi and camera for computing object speed.  The device was stationary, outside the moving object.  (I didn’t know what “screw to the structure” referred to.)

Mike

Why the specific exclusion of GPS?

If you want cheap, it will be necessary to use GPS.

Have a look at race car/bike lap timer smartphone apps as they will do what you want. What I do not know is if they are tied to a particular circuit or have to work on the basis of a ‘lap’ (i.e. something that starts and ends in the same place.

Just some tasters:

https://www.gps-laptimer.de/products

https://www.pistonheads.com/gassing/topic.asp?h=0&f=198&t=1440523

https://vibhubithar.medium.com/collecting-vehicle-telemetry-with-pi-por-tel-device-d0d86bf08333

(https://github.com/vibhubithar/pi-por-tel)

https://www.linkedin.com/pulse/budget-race-car-data-acquisition-peter-connell

~.amazon.co.uk/Accelerometer-Logger%E3%80%91WT901SDCL-High-Precision-Magnetometer-Inclinometer/dp/B085NWVRS2

~.amazon.co.uk/Accelerometer-Inclinometer-WT901BLECL-High-Precision-Magnetometer/dp/B08SQCTN8M

Being Arduino minded makes that route attractive to me, especially as I didn’t know a cheap off-the-shelf solution existed until Michael found one!   Quite likely there are Smart Phone apps too, because all Smart Phones contain an accelerometer.

This Arduino project shows how its done.  As the program is written, the Arduino / accelerometer combo isn’t stand-alone – it copies accelerometer data to a another USB connected computer, which may not be convenient.  Depends on how big Gerry’s vehicle is.  Not difficult to write the data instead to an SD-card, if you know how, but Gerry may not have the time or interest to get into that.   I could have a go, but might take a while because I’m wading through treacle at the moment due to illness.

What do do with the data once collected may be a complication.   The simple case is horizontal acceleration in a straight line, which matches Gerry’s requirement, so shouldn’t be a problem.  Only one rate of change matters, keeping life simple.   Accelerating around a circular track is harder to compute because the X and Y accelerations have to be combined – because the vehicle is moving in two dimensions.    A model aircraft accelerating around a circle whilst climbing and diving is even worse.    Calculating the aircraft’s acceleration requires integration of acceleration data in all three dimensions, X,Y and Z. Hard work, at least for me.

Dave

The Arduino Nano 33IoT has a built-in 6-axis IMU plus Bluetooth Low Energy and WiFi, and lots of application examples.

https://store.arduino.cc/products/arduino-nano-33-iot

On 10 June 2024 at 20:34 dodmole Said:

I think if I remember correctly a BBC micro:bit does the data logging you require, nice and simple and self-contained.

This project describes such a thing, developed in Scratch.   It uses wifi to send the data to a remote laptop. This might be a gotcha, because it would be better to log to a file on an SD card and I’m not sure the micro:bit supports them.

Dave

I recall having an accelerometer based performance meter back in the early 2000’s , it was a g-tech performace meter that could measure 0-60 and 1/4 mile times, no data download and such on it though.

It appears that RC modelers have already developed a fully self contained GPS device for performance measurement which includes a phone app to study the data, as is the way these days.  linky:

https://www.skyrc.com/gsm020

edit to add they are in the region of £60