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Static friction parameter issue

Hello everyone,

i have modeled a real joint that I am using in Gazebo and I am currently trying to set up the parameters (damping, static friction). I let the real link fall from an initial angle only under the effect of gravity and tried to match the response of the model. I achieved that, with parameters close to those I would have imagined (damping = 0.005, static friction coefficient = 0.64). The real and the simulated link stop at the same angle (non-zero, because of the friction and the damping) and fall for the same amount of time.

The problem appears when I use the ROS pid controller. When I give a setpoint to the simulated link, its response is very strange (I have attached a picture). X axis depicts time in seconds and Y is the joint angle. image description

If I change the static friction coefficient the only thing that changes is the settling time and not the steady state error, which strikes me as weird, as in the case of the free fall this parameter defined where the leg would stop. If i set it to zero the response is realistic but the steady state error is smaller than the real one (that is the reason I used the static friction in the first place).

If anyone could assist me I would greatly appreciate it. If I have not expressed myself clearly or any further clarification or information is required please do tell me.

Thank you all in advance.