Authors: Zhiquan Zhang, Tianyu Li and Nadia Figueroa
Abstract: 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 C2 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.
12 сен 2024
