  In Human-Robot Collaboration, the robot operates in a highly dynamic
environment. Thus, it is pivotal to guarantee the robust stability of the
system during the interaction but also a high flexibility of the robot behavior
in order to ensure safety and reactivity to the variable conditions of the
collaborative scenario. In this paper we propose a control architecture capable
of maximizing the flexibility of the robot while guaranteeing a stable behavior
when physically interacting with the environment. This is achieved by combining
an energy tank based variable admittance architecture with control barrier
functions. The proposed architecture is experimentally validated on a
collaborative robot.
