  Although autonomous control of robotic manipulators has been studied for
several decades, they are not commonly used in safety-critical applications due
to lack of safety and performance guarantees - many of them concerning the
modulation of interaction forces. This paper presents a mechanical probing
strategy for estimating the environmental impedance parameters of compliant
environments, independent a manipulator's controller design, and configuration.
The parameter estimates are used in a position-based adaptive force controller
to enable control of interaction forces in compliant, stationary, and
non-stationary environments. This approach is targeted for applications where
the workspace is constrained and non-stationary, and where force control is
critical to task success. These applications include surgical tasks involving
manipulation of compliant, delicate, moving tissues. Results show fast
parameter estimation and successful force modulation that compensates for
motion.
