Is it possible tracking the position and the velocity of a mechanical pendulum by using a Kalman filter Simulink block? I tried it and I just got a good estimation of the angle but not the velocity which is totally wrong.

Good afternoon, I implemented an easy mathematical model of a pendulum on simulink. I implemented a Kalman filter to estimate the velocity state having as input a zero torque, the initial position set to a certain angle (pi/18) and the initial velocity set to zero. I suppose to have just a position measurement as the output of the system and the goal is to have a good estimation of the states. I expect to obtain a good estimation of the angle and the velocity but, as far as the velocity estimation is concerned, it is totally wrong. I think there is something wrong in the block diagram. The question is: it is possible to have a "good" estimation of both the state using a Kalman filter for a mechanical linear such as a Pendulum? IS it possible to obtain that result using the Kalman filter simulink block? Thanks in advance

Jacopo Riccio