  Passivity is necessary for robots to fluidly collaborate and interact with
humans physically. Nevertheless, due to the unconstrained nature of
passivity-based impedance control laws, the robot is vulnerable to infeasible
and unsafe configurations upon physical perturbations. In this paper, we
propose a novel control architecture that allows a torque-controlled robot to
guarantee safety constraints such as kinematic limits, self-collisions,
external collisions and singularities and is passive only when feasible. This
is achieved by constraining a dynamical system based impedance control law with
a relaxed hierarchical control barrier function quadratic program subject to
multiple concurrent, possibly contradicting, constraints. Joint space
constraints are formulated from efficient data-driven self- and external C^2
collision boundary functions. We theoretically prove constraint satisfaction
and show that the robot is passive when feasible. Our approach is validated in
simulation and real robot experiments on a 7DoF Franka Research 3 manipulator.
