# Wheeled robot

### Types

#### Differencial

The differencial drive robots have two parallel wheels motorized each one separately. If both the wheels are driven in the same direction and speed, the robot will go in a straight line. If both wheels are turned with equal speed in opposite directions, the robot will rotate about the central point of the axis. Otherwise, depending on the speed of rotation and its direction, the center of rotation may fall anywhere on the line defined by the two contact points of the tires. While the robot is traveling in a straight line, the center of rotation is an infinite distance from the robot. Since the direction of the robot is dependent on the rate and direction of rotation of the two driven wheels, these quantities should be sensed and controlled precisely.

1. Self-balancing: The center of gravity of the robot body is kept below the axle. It needs at least two sensors, a tilt sensor that is used to determine tilt angle and wheel encoders which keep track of the position of the platform of the robot.
2. Differentially steered: Apart of the two motorized wheels, has a additional free rotating wheel to keep the body in balance.

#### Skid steer

1. 2-by-2 powered wheels: for tank-like movement, that is to say, it will works like a tracked robot.

#### Car-like steering

This method allows the robot to turn in the same way a car does. It only needs one motor and a servo for steering.

1. 3-4 wheels - 1 motor 1 servo: Can have 3 or 4 wheels, but the way to work is the same. The motor also can track in the front wheels.

#### Multi directional robot

All the multidirectional robots have individual traction on all wheels. We have indentify two types differentiated by their kind of wheel: You can see the way that they works in the following images:

1. Omni wheels
• 3 wheels - 3 motors
• 4 wheels - 4 motors
2. Mecanum wheels