I have a Simulink model that has a standard Simulink block that determines the Jacobian for a given Rigid Body Tree model. The Rigid Body Tree model is a built in model of the Franka Emika Panda robot and is loaded into the workspace using:
panda_matlab = loadrobot("frankaEmikaPanda").
The input to the block consists of the robots configuration (config), which is determined by the joint angles $q$. In this case all the joint angles are $0$. This means that the robot is in an upright position and joints 3 and 5 depend linearly on joint 1 Which means that columns 1, 3 and 5 of the Jacobian should be identical. This is indeed the case, However the Jacobian also has one row of zeros. I do not understand where this row of zeros come from.
I also used my own, simplified Panda model with fewer links. In the same upright position with, the same linearly dependent links. The jacobian matrix of this model is shown below. This also has a row of zeros in the Jacobian.
What is causing the jacobian to have this row of zeros?
Thanks in advance.