Linear and angular velocity control commands

**Library:**Robotics System Toolbox / Mobile Robot Algorithms

The Pure Pursuit block computes linear and angular
velocity commands for following a path using a set of waypoints and
the current pose of a differential drive robot. The block takes updated
poses to update velocity commands for the robot to follow a path along
a desired set of waypoints. Use the **Max angular velocity** and **Desired
linear velocity** parameters to update the velocities based
on the performance of the robot.

The **Lookahead distance** parameter computes
a look-ahead point on the path, which is an instantaneous local goal
for the robot. The angular velocity command is computed based on this
point. Changing **Lookahead distance** has a significant
impact on the performance of the algorithm. A higher look-ahead distance
results in a smoother trajectory for the robot, but can cause the
robot to cut corners along the path. Too low of a look-ahead distance
can result in oscillations in tracking the path, causing unstable
behavior. For more information on the pure pursuit algorithm, see Pure Pursuit Controller.