I ask the robotics specialists for help as I am a little confused.
I have two subsystems which are shown in the picture below:
One of them is a system of stable and controlled differential equations of motion for robot.
Second is a block that implements a Forward Kinematic $f(\theta)$ from a signal entering its input.
$\theta,\Phi,\phi$ - position of drives, positions of end-effector from dynamic model and Forward Kinematic data, $u(t)$ - control signal.
I came across this article and a diagram from it.
Task: choose the structure of the mathematical model in such a way that $\phi=\Phi$. In the above diagram, I am confused by the fact that a block of direct kinematics is used to estimate the angular position of the robot, and, generally speaking, this mechanical coordinate should be available through the equations of motion.