It is easy :-)) ... There are several instrumets made by producers of 2.4 GHz r/c equipments capable of doing this. An example could be Jeti production which can consists of current and GPS sensors which could be connected either to some device showing data like Jetibox profi or even to receiver which can send data wireless to Jetibox profi in real time which either show data on place in your hands or you can analyze on PC in specialized program which can eve show trajectory on map :- )))

http://www.jetimodel.cz/data_downloads/101/mui_en_v20.pdf
http://www.jetimodel.cz/data_products/downloads/204/navod_mgps_en.pdf
http://www.jetimodel.cz/data_downloads/106/jetibox-profi-en-web.pdf

Hello Igor,
Thank you very much indeed for pointing my friend in the right direction. The Jeti equipement sounds ideal for the project. and being a mass produced item will not break the bank! I figured that someone on the forum would have sorted out the problem . So no need to reinvent the wheel. When I was working some 10 years ago, I did indeed use a simple datalogger programme, so such things must be very commonplace and that would just about tie up the whole project.
Expense isn't too much of a barrier, as research funds and technicians are available to do the nitty gritty! My friend doesn't have much practical experience and I was "recruited" so that he could ask the right questions and suggest ways of setting up the experimental kit. Basically he didn't want to appear to be technologically challenged!
The whole point of the exercise is to provide data to help in planning new infrastructure, whilst taking account of the needs to make things easier for  invalids. My sincere thanks for your help.

Andrew.

Andrew, that eagletree logger which Dean wrote reminded me one important thing which your friend must understand or check or solve. If you compare Jeti stuff and Eagle tree stuff, you will see the way where modern R/C stuff goes. Since we have 2.4GHz technology, both receiver and sender are almost idenical devices, because communication is duplex. Transmitter sends commands to recever, and receiver send other data back. That other data could also current to motor or gps coordinations. It means that currently all sensors in model does not have memory, they simply send data back to ground. It means memory for data is typically on ground, not in model, and it little bit changes situation, because the device with memory is the Jetibox profi in case of Jeti stuff - means the displaying unit collects data (which can, but not needs to be physically connected if you use receiver - because the box has also receiver), which you can later download to computer.

On opposite side Egletree with roots in pre-2.4GHz age has memory on board. So displaying unit is is only simple display.

I am writing this difference because of 2 things - it can have some practical issues (what the user on chair sees on display if any, and how to transfer data to PC)
and the second - your friend must check memory capacity of those devices, because both are primary designed for shorter time like few flights, not day or more. Some devices have even compression which can improve logging time when chair does not move etc.

And one small note on end - in the case that memory is too small and values are stored in longer time intervals, it is good to check if capacity is really measured and stored, or calculated from voltage and current - this can give erratic data.

I'm not sure that doing this with RC hardware is the best approach, particularly if he's not already familiar with it, and if the trips are going to be long (does the already-mentioned equipment work for a 6-hour "flight" through London?).

You can get GPS receivers that have serial outputs.

You can get multimeters (to measure current) that have serial outputs.  (Or hardware from National Instruments, which may be better or may be worse).

You can get usefully small tablet PCs that don't need much space or power.

If you have technicians with software ability, you can log the incoming data from GPS and multimeters along with timestamps, then put everything together as needed.  Presumably he wants a track plus current consumption -- that can be done easily.

There's lots of ways to skin this particular cat; which way is best depends a lot on what his budget is, what his accuracy requirements are, what sort of talent he has available, and how many he's making (the approach to making a one-off is way different than for a batch of 100, which is way different again from a batch of 10,000).

Hello Gentlemen,
I had a long talk with my friend last night. John Schoon is currently working at Southampton University UK, after a long spell at North Eastern University in Boston, where he was a Professor in Traffic Management. He has now decided to concentrate on the interaction of pedestrians with traffic(!) and more recently in the problems experienced by the disabled. So that is the background. He has some funding for the project and backup in terms of technicians to implement the programme.
He was delighted at the thought of having a self contained unit aboard the wheelchair with a 2.4GHz radio system to relay data to a fixed station. The range of operations would not be too great as to preclude a limited range data link. The ability to use relatively cheap R/C items would mean he could get up and running relatively quickly and get some initial data. Long term, maybe a system that is self contained on the wheelchair would be a better bet. The R/C system could be up and running quickly and would pinpoint areas that need concentrating on.
He is also interested in measuring the problems that manual wheelchair users have (The type of chair that uses handpower to drive them). There are torquemeters that are used in bicycles that record the power going into the driven rear wheels. My son is a cyclist and he is looking into that aspect!
So a whole range of disciplines are being used for this programme! I am delighted that electric C/L has made an extremely useful contribution. Makes a big change from the sterile debate of IC versus electric and FAR more useful! Thanks again to everyone that contributed and to Dean Pappas for allowing a non control line topic to be discussed on my favourite forum!

Andrew.

Hello All,
Just an update on the invalid chair theme. After some thought, my friend John Schoon has decided to go for the Eagletree system of data logging. It is simple and has enough memory for the type of trial that we need to conduct. I shall be doing the installation and we hope to have the project up and running in the next few weeks.
My thanks to everyone that has responded on this topic. It certainly helped to get up to speed. John has been tidying up his last experimental work and now we have the decks cleared to get this project up and running.

Thanks again,

Andrew.

Thanks Dean,
I will report back when we have some results. The whole object of the exercise is to design new developments and areas with an eye to minimum work for those people who use arm powered wheelchairs as well as people being pushed in wheelchairs. John is a traffic expert and when he was looking at pedestrian crossings he realised that not all pedestrians are equal! His researches started to take a new turn to the benefit of all disabled folk. Ian Rustle (Rustler) has already offered me a self propelled wheelchair and I took him up on his kind offer!!!! So I have a vested interest in this.

Best regards,

Andrew.