Friday, September 18, 2009

Overhead course pole design

Here's an sketch for an idea for making a wiiCane course with an overhead string of LED lights that will allow us to track position along a course and also to observe cane arc and veering. The best part about this is that it is mostly parts from IKEO, so it will be very inexpensive to set up a course. The picture shows a pole with a video screen and a plywood box mounted to it. At a point 8' above the floor, there's a fitting on the pole that is used to hold each of the three cables in tension. A cable comes out of the middle of the pole to supply electric and control to the lights.

1 comment:

zeveland said...

Promising design overall, but I have to throw out a few words of caution.

First, it's going to be very difficult (and potentially unsafe) to use three-wire cable as the tension cable. Standard three-wire cable won't be rated for the (I'm guessing) > 50 lbs. of tension that will be needed. Even with jacketed cable, the tension on the solder or connection points to each board will be much weaker.

Instead, I'd suggest a single steel cable as the tension element with the lights hanging from that cable and connected to each other with a slack three-conductor cable similarly suspended from the steel cable.

Second, it's not clear from the drawing how the individual nodes terminate to the three-wire cable, but whatever approach is used will need to be electrically robust. Steven and I discussed a system like the one used by some low-voltage halogen light systems where the individual lights have contacts that rest on two electrified cables. That works fine for two cables but trying the same with three cables will lead to all sorts of intermittent connection problems.

I've got more experience than I'd like with simply hanging electronics from three conductors. The problems that result when one contact "lifts" are very difficult to debug. I'd suggest instead that all termination be done with either a solder joint or a suitable connector.