The Unibot is a self balancing unicycle robot. This robot combines the principles of the famous wheeled inverted pendulum and inertia wheel pendulum.
A well known application of the wheeled inverted pendulum is the Segway. Take one wheel off the Segway and add an other one perpendicular to and above the remaining wheel and the Unibot is born!
The wheel on the ground is used to establish the stabilization in the y-z-plane. The wheel in the air is used to balance the robot in the x-z-plane.
It is easy to see that this system is unstable when no control is applied to it. In order to obtain a stable system, both wheels are actuated by DC motors.
The dynamics of the system is devided into two two-dimensional systems. Each system contains one wheel and one motor. For simplicity, the dynamics of both systems are considered to be decoupled.
Currently a prototye is being built. Acrylic frame parts have been manufactured by using a Lasercamm. Most drive train parts have been bougth and some other parts were made by conventional techniques like lathing.
In both planes a gyro and an accelerometer are used to measure the angles and angular velocities of the robot. Both motors have an optical encoder to measure the relative angles between wheels and body.
The Unibot
