  The topic of physical human-robot interaction received a lot of attention
from the robotics community because of many promising application domains.
However, studying physical interaction between a robot and an external agent,
like a human or another robot, without considering the dynamics of both the
systems may lead to many short-comings in fully exploiting the interaction. In
this paper, we present a coupled-dynamics formalism followed by a sound
approach in exploiting helpful interaction with a humanoid robot. In
particular, we propose the first attempt to define and exploit the human help
for the robot to accomplish a specific task. As a result, we present a
task-based partner-aware robot control techniques. The theoretical results are
validated by conducting experiments with two iCub humanoid robots involved in
physical interaction.
