I am reading the following research paper regarding Trajectory tracking of mobile robots.
There are two things at the start of the paper that i do not understand.
1) The author derives equation(14) as the state space model of the system in which he considers the error as the state. Can anyone please elaborate on why he is using the error as the state space model of the system and not the Vx, Vy, and w(Omega, angular speed) of the robot.
2) Why does the author linearize the system around the reference trajectory?