Cylinder Balancer

Barrel Bot Diagram

Diagram

This project is both a robotics project and an experiment comparing the effectiveness of several different control theory algorithms. My idea is a robot that will balance on a cylinder that is turned on its side as illustrated in the diagram on right.

So far I’ve made the physical structure of the cart, and a circuit board containing the motor controller and sensors.

The project uses both an accelerometer and a gyro for orientation data and a wheel encoder to get accurate velocity data.  Eventually, it will be possible to control the robot remotely by adjusting the target velocity.

I hope to investigate several different controllers including at least PID and Fuzzy Logic.  If possible, I will also try to make these controllers self adaptive so that they can tune themselves.

Related Posts

Much more information about the individual components is available in these posts

Display

Display Board Design (Click for .pdf).

Simulation

An applet that simulates this system is accessible here:  http://keegan.webhop.net/applets/cynbot_sim

The yellow circle is the cart. Currently, the controller is not simulated so the position of the mouse relative to the center of the screen is the PWM value sent to the simulated motor. As you can see, it’s almost impossible to balance the cart on top of the cylinder manually even though the moment of inertia of the cylinder is set to a relatively high value. The cart falling off the cylinder isn’t simulated either so it’s as if the cart sticks to the surface of the cylinder.

Here are some pictures:

Side View

Motor Controller and Sensor Board

Motors and gearbox

Drawing

Original drawings a made for the robot

Controller Diagram for the Robot. It's essentially a nested PID.

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