This robot only has three wheels, but they are very special. They are called Omni wheels and can move in two directions.
Top View
This shows the top of the robot with all the control computers. The blue board is the “brain” and the red board drives the wheel motors.
Side View
This photo shows the whole robot with its three wheels. The base is metal but upper deck is plastic that I cut and built to hold the electronics.
The Magic Wheels
These are the Omni wheels. They rotate as usual but have rollers on the edge of the wheel. This means that the wheels can move sideways easily.
Here is a link to more descriptions. https://en.wikipedia.org/wiki/Mecanum_wheel
I will add a video of the robot moving as soon as I have worked out how to move a robot with three wheels! The maths is very complicated and uses vectors. But the Reverse Kinetics needed to ensure the robot reaches a destination is even more complicated.
But this is too complicated to start your journey into the wonderful world of robots. So we will start with small Lego based robots. We will return to this robot later.