1. AX22 Introduction
1.1 What is the AX22?
The AX22 is a comprehensive data logging system that can be installed in minutes. The AX22 can be used to either carry out measurements on the car (for example acceleration times, braking distances or lap timing) and view the results on its screen, or log data to compact flash and carry out a more complete analysis on a computer.
Installing the AX22 couldn't be much simpler, it is normally mounted on the windscreen using the "Cullman" suction mount, and adjusted so it is approximately level. Power comes from either the cigar lighter or another 12v source. Finally, the magnetic mount GPS antenna should be mounted on the car's exterior - and you are ready to go!
The AX22 is built in a sturdy aluminium housing with a large suction cup, it uses the latest in high accuracy GPS and silicon accelerometers to give excellent measurement accuracy.
1.2 Who is the AX22 designed for?
Because the AX22 is so quick and simple to install and use in different vehicles, the AX22 is ideal for:
- car enthusiasts who want to know more about their cars and improve their driving,
- race driving instructors
- car testing professionals
- accident reconstruction engineers
- magazines who road test cars
- Track day testing with on board lap timing (where allowed)
1.3 What does it do?
Principally, the AX22 stores very accurate vehicle speed and acceleration data on to a memory card for detailed analysis on a computer. This data is also processed internally to give:
- Measurements between two speed, including time taken and distance travelled. Ideal for brake testing or 0-60mph sprint testing
- Measurements over a fixed distance, giving the time taken and speed at the end of the run
- Acceleration over a fixed quarter of a mile
- Lap and sector timing live on the screen, including comparisons with best lap and sector
- Accurate power at the wheels measurements
- Bar graph displays of current g-forces
- Real-time GPS data
During each of these tests, the data is stored at 100Hz on to a compact flash memory card, so the data can be further analysed using the Analysis software package.
1.4 Why use GPS?
One of the key features of the AX22 is its built in high accuracy GPS system - this gives the AX22 advantages over other data loggers in two key areas - greatly improved track maps and far more accurate speed data.
Conventional data loggers require a "closed circuit" to enable them to calculate the track map; the shape of the track is estimated from a combination of the lateral acceleration and speed. This works adequately in some situations but it becomes increasingly inaccurate for long tracks and impossible for open circuits, motorbikes or boats. In contrast, the GPS will produce high accuracy track maps in almost any situation.
While speed is probably the most important parameter that anyone wants to measure using the data logging system, it is also the most inaccurate in a "conventional" system. The normal way to measure speed is to simply attach a pickup to a wheel to detect how fast it is rotating - but the rolling circumference of a tyre changes by 4% just with wear and temperature. Even worse, the error increases significantly under race conditions where the tyre is under loaded - typically the tyre slips by about 20% under hard braking going into a corner. Measuring speed using GPS is now common practice in high-end systems - under typical conditions speed error is well under 1%!
“Please note: The AX22 is not compatible with the VIDEO4”