This is an idea I wanted to try for a while. Basically, it uses one servo to drive the main wheel and a connected (90 degree) servo to turn that servo for steering. The concept of my "big wheel" "trike" works quite nicely. I am using a Digilant uC32 in "pure" Arduino C/C++ code mode to control the bot. Of all the ways to program a robot, this still remains one of the easiest. Special features include a pot on an analog input to control the PING))) ultrasonic rangefinder "trigger" distance. At that point the robot looks around and finds another route. There is also code to help the robot get out of situations in which it gets "trapped" between objects. It works most of the time and the robot seldom gets itself "stuck". Metal parts and other items? From other kits (some of which look like they came right out of an "Erector Set"! :-) (Screws, nuts, paper tape, and double-sided foam tape hold the entire bot together.) It only took a day and was definitely a "fun build".
An interesting 3 wheel bot.
- Actuators / output devices: 2 servos (one continuous rotation and one standard)
- Control method: autonomous
- CPU: Digilant uC32 (Arduino compatible)
- Operating system: MPIDE
- Power source: 6 Rechargeable AA cells
- Programming language: C/C++
- Sensors / input devices: PING))) sonar
- Target environment: indoor flat surfaces
This is a companion discussion topic for the original entry at https://community.robotshop.com/robots/show/3-wheeler-using-2-servos
Good to see you get back to us Will.
Your build looks interesting. I would ask for video, but, I bet that is asking a lot. 
Always impressed with your constant dabbling in different uC architectures.
Added 2 old Easter bunny ears…
Same robot, really new “ohhh so cute!” looks!
Now I need to add a simple “clap” detector using a ectret mic and a amp/dc converter into one of the A to D’s.(Just so the bot changes direction when it hears a loud clapping sound). Neat idea? Have to figure that one out…
To Maxhirez about the electret circuit…
So far, no success, but I think I have a bad electret from a discarded tape recorder I took apart. So far I tried a very simple one transistor amplifier I saw on a website (sorry, but I didn’t bookmark the address) and then discovered the electret itself was probably bad. I think I have to keep the ADC input to no more than 3.3V because I am using a uC32 for my controller, so that can be another fun problem… I experimented a bit, and tried a simple (2 x 2N3904) Darlington style amplifier but still no joy. Got to get a new electret… Lots of diagrams use a “386” IC audio amp for the electret amplifier, but they draw more current than I am willing to use. I have this neat little “flex” type stress sensor I want to use with a small deflecting weight too. If it senses a “above normal” deflection I can perform some action (maybe a nice “reverse” in that case???) I think the flex sensor came with a “Arduino getting started kit”, but I am not sure about that. It is maybe 2 inches long and it (wired in series with a big resistor to 3.3V gives out a very nice ADC change when it is bent. Not unlike an accelerometer I believe (I could be wrong. That happens more and more when you get old like me. LOL) Case in point: I did but that “Official” Arduino robot and I couldn’t recommend it for an individual purchase… A school, possibly yes.
Always impressed with your constant dabbling in different uC architectures.