# Physical Models¶

Physical Models define the translation from a velocity and curvature into wheel velocities. This additional limit is imposed to prevent conditions where the robot’s linear velocity is within the velocity constraint but one of its wheels would need to exceed the velocity constraint to match the curvature at the point. The generated wheel velocities can also be used as a feedforward value in the control loop for following the path.

## Tank Drive Model¶

The TankModel defines a Tank Drive model according to the unicycle model. This model translates the linear velocity and curvature at the point into two values: a velocity for the left side of the robot and a velocity for the right side. These velocities are used when constraining the robot’s linear velocity. Additionally, the acceleration of each wheel is accounted for using the robot’s linear acceleration and the curvature at the point. This additional constraint on the acceleration is applied during the motion profile phase of the path generation.