Sunday, December 30, 2007

Seat of the Pants

As many of you know, I'm an avid racing enthusiast and I've got a pretty good setup at home for playing PC based racing simulations. One of my particular favourites is Live for Speed (www.lfs.net).

Most of these games are now realistic enough calculate the forces acting on the car/driver and many people have developed home-brew "motion seats" allowing the player to "feel" the car in the simulation.

One company in Japan (www.frex.com/gp) offers a commercial kit for building a home motion seat. I was particularly interested in this but concluded it is over expensive with prohibitive shipping costs and production delays.

I've decided to start out on a project to build a simpler kit providing a motion seat for home racing enthusiasts here in the UK and Europe. During my research I discovered a great piece of software called X-Sim (http://www.x-sim.de/) which already contains links to Live for Speed and connects to a variety of hardware interfaces. So with X-sim and a basic design in my head I set out to build a small model prototype of a motion seat...




The video above shows my first attempt at getting motion from a crude cardboard platform (complete with Teddy that my girlfriend Lucy got me during a holiday in Gozo ;-) ). The PC interface is a Velleman K8055 USB i/o card connected to a dual h-bridge motor driver IC. The 2 servo motors are basic RC servos with the electronics removed.

Although the X-Sim software is great (I would recommend it to any diy motion builder) it has a couple of constraints that are causing the motion not to be completely accurate. Also the servos used here are relatively slow and only driven at a single speed currently.

Anyway, it works pretty well for a quick design test. Obviously being made from cardboard and paper clips it is not perfectly calibrated but as a first foray into PC controlled motion... quite exciting!