The Base Chassis

OK.  So, I've decided to build a vehicle that can drive itself around a building using only onboard sensors to guide it.  I don't really have time to build the mechanical parts from scratch, so I decided to do what many other AVC contestants have done, which is to start with a RC car, or truck of some sort, strip it down to the essentials and then add back only what I need.  Not having a lot of experience with RC cars, I went down to my local model shop, picked a few brains behind the counter and finally settled on a 1/10-scale RC Short Course Truck called a Torment that's made by ECX.

The basic design of the truck is fairly simple.  There a brushed DC motor controlled by a device called an ESC (electronic speed control) and steering servo.  Both are controlled by series of pulses that normally come from an RC receiver.  If you want to know more about how this works, see this page.  My plan is to replace the receiver in the truck with a computer that can control the ESC and the steering servo by using an onboard computer to mimic the signal pulses that normally come from the RC receiver.  This is actually fairly easy to do with an Arduino and, in fact, there is already a wealth of example code on how to do this on the Arduino home site.  But, more about this in a future post.

Next, I removed the plastic body of the car and attached a flat piece of foam core board on top using the same plastic protrusions used to affix the molded plastic truck body.  This gives me a nice surface where I can use tape and/or velcro to attach the circuits that are going to drive the car around.  The image above shows some early test circuits mounted on the foam board, but I'll go into how the electronics work in future posts.

Next: Steering to a Heading