  Series elastic actuators (SEAs) are growingly important in physical
human-robot interaction (HRI) due to their inherent safety and compliance.
Cable-driven SEAs also allow flexible installation and remote torque
transmission, etc. However, there are still challenges for the impedance
control of cable-driven SEAs, such as the reduced bandwidth caused by the
elastic component, and the performance balance between reference tracking and
robustness. In this paper, a velocity sourced cable-driven SEA has been set up.
Then, a stabilizing 2 degrees of freedom (2-DOF) control approach was designed
to separately pursue the goals of robustness and torque tracking. Further, the
impedance control structure for human-robot interaction was designed and
implemented with a torque compensator. Both simulation and practical
experiments have validated the efficacy of the 2-DOF method for the control of
cable-driven SEAs.
