Let's Make Robots!

Everything you never wanted to know about two wheel drive.

Platform Drive Control.

This platform is driven by two wheels mounted so that the wheel axis
is just off center. There is a small caster wheel mounted in the 'rear'.

At this time there is no speed control feedback.

Maneuvers are accomplished by independent but coordinated control of
each wheel motor.

The drive motors are servos that have been hacked to continuous rotation.
The servo hack involved pulling the feedback control board and pot as
well as cutting the stop on the main gear. Thus the servos are converted

YellowBot Source Code

I have not put togethger documentation for my Bots code. The code is evolving too quickly for detailed up front documentation. I would like tos tate that a primary goal of doing this Bot was to help me learn Object Oreinted Programming, as well as get me used to programming again. it's been 20 years since I've written something more than a simple shell. python or Perl script.

Thus I will warn you this code is chocked full of redundancies and inefficiencies. Bear with me, an old dog is learning new tricks, it's just taking time :) 

IR Sensor Info

IR Sensor Info

IR distance sensor - Sharp GP2YOA21YKOF
This sensor has a range of 10cm - 80cm. Approximately 4" - 32".
The sensor outputs an analog voltage based on the object distance. The
voltage ranges from 3v for a near object to .4v for a distant object.


The IR sensor is mounted on a a servo that sits on the rotating base.
This gives both an X and Y axis movement to the IR sensor. The base
rotation will sweep the sensor back and forth, across the width of the

Yellowbot, the circuit, or I love Fritzing.

While messing with my Arduino I found the circuit diagraming program Fritzing. I really love this program, it makes docummenting breadboard circuits increadibly easy.

You can get the software from their site: fritzing.org

YellowBot, project overview.


The platform should be able to independently navigate our normal household
without getting stuck in/under something or falling down the stairwell.

This project has been down using previously purchased kits and very little
additional hardware. All of this is done using an ArduinoUno.

The platform drive system is a two wheel setup using a frewheeling cater wheel
at the rear.

The platform has been setup with a breadboard and mounting for the Arduino.

The Arduino is powered by a 9v battery.

Obstacle avoidance via IR sensor.
Using a
My goal is to create an obstacle avoiding mobile platform. I'd like to add a Raspberry Pi to supply remote communitions and some control. The platform should be … Read more