Bionic soft robots offer exciting perspectives for
more flexible and safe physical interaction with the world and
humans. Unfortunately, their hardware design often prevents
analytical modeling, which in turn is a prerequisite to apply
classical automatic control approaches. On the other hand,
also modeling by means of learning is hardly feasible due to
many degrees of freedom, high-dimensional state spaces and the
softness properties like e.g. mechanical elasticity, which cause
limited repeatability and complex dynamics. Nevertheless, the
realization of basic control modes is important to leverage the
potential of soft robots for applications. We therefore propose
a hybrid approach combining classical and learning elements
for the realization of an interactive control mode for an elastic
bionic robot. It superimposes a low-gain feedback control with a
feed-forward control based on a learned simplified model of the
inverse dynamics which considers only equilibria of the robot’s
dynamics. We demonstrate on the Bionic Handling Assistant
how a respective inverse equilibrium model can be learned and
effectively exploited for quick and agile control. In a second
step, the control scheme is extended to an active compliant
control mode. It implements a kind of gravitation compensation
to allow for kinesthetic teaching of the robot based on the
implicit knowledge of gravitational and mechanical forces that
are encoded in the learned equilibrium model.We finally discuss
that this control scheme may be implemented also on other
soft robots to provide the avenue towards their applications in
general manipulation tasks.