I am trying to implement a compliance controller for a robot arm and stumbled upon an existing code snippet where the compliance velocity of the endeffector is calculated by:
$v_{out} = v_{in} + \frac{F}{K} - \frac{\dot{F}}{B} $
where $F$ is a 6D wrench vector, $K$ is a given stiffness with the units $\frac{N}{m/s}$ & $\frac{Nm}{rad/s}$ and $B$ is a given damping with the units $\frac{N}{m}$ & $\frac{Nm}{rad}$.
I don't understand where this equation comes from, in particular the second part. In (cartesian space) admittance control, there is e.g. the equation $\dot{x}=C \cdot F$, where C is the compliance, thus the inverse of stiffness $K$. But how to explain the second part $\frac{\dot F}{B}$? Is there any reference literature which are recommended?
Many thanks in advance!