Robot Platform Kinematics

The robot platform mentioned here is a differential drive robotic platform. The topics that we will be handling in this post is:

• Differential Drive model
• Unicycle model (Design model)
• Relation between the two models

Differential drive model:

As we can guess from the name, a differential drive model uses two wheels to achieve the desired motion of the robot. The velocity and direction of rotation of two wheels decide the direction, linear velocity and rotational velocity of the robotic platform.

So summarization:

 

Unicycle Model:

In unicycle model we simplify the model by considering jus the following terms:

• Velocity of the platform ( Unlike Left and right wheel velocity in Differential drive model)
• Angular velocity of the platform

Relation between the two models:

The differential drive model relates the left and right wheel velocities with the robot motion and the unicycle model relates the platform velocity with the robot motion. The parameters in differential drive is something that can be controlled. The parameters mentioned in unicycle model is something that we desire to happen. As you might have observed the LHS values in both the models are same. This can be used to equate the equations in the two models. Once equated we get the relation between parameters we can control to achieve the desired motion of the platform.