My daughter has been in and out of the chair for a few months while recovering from simultaneous injuries to BOTH ankles
- Ouch, I hope she makes a good recovery.
will get some technical advice from long term chair users. For some of them, this will be the first time they have ever been asked for advice.
As a non-user I admit I was a bit sceptical about the signaling options but the point was to ask so if that is the feedback go for it.
The GPS idea is a bit advanced because of the display requirements if you go down the mapping route, but speed distance etc. would be feasible.
Sail: You are right, that would be cool, but not really an Arduino project.
It was a wild idea, and you did ask for ideas. It might not be totally daft though and maybe not totally outside the limits of an Arduino. In fact I may just have devised a new paralympic sport. Imagine a sand yacht where the sail is motor controlled.
Here is a link to bicycles with sails, I know we are stretching the topic of your post but you may find it of interest.
The Dutch seem to have been the first to put sails on bikeshttp://www.whike.com/en/pagina/25/about-the-whike