Abstract
Robotic tasks featuring interaction with other bodies are increasingly
required in industrial contexts. The manipulators need to interact with
the environment in a compliant way to avoid damage, but, at the same
time, are often required to accurately track a reference force. To this
aim, interaction controllers are typically employed, but they either
need human tinkering for parameter tuning or precise modeling of the
environment the robot will interact with.
The former is a time-consuming procedure, while the latter is
necessarily affected by approximations, which often lead to failure
during the actual application. Both these aspects are problematic if it
were often necessary to change the contact environment.Current research
is concentrating on devising high-performance force controllers that are
simple to tune and quick to adapt to changing environments.
Along this line, this work proposes a novel control strategy, that we
term ORACLE (Optimized Residual
Action for interaction Control with Learned
Environments). It exploits an ensemble of neural networks to
estimate the force generated by the robot-environment interaction. This
estimate is input to an optimal residual action controller that locally
corrects the main action, output of a base force controller, which
guarantees stability.
The ORACLE strategy has been implemented and tested in the MuJoCo
dynamic simulator and in a real-case scenario, both foreseeing a Franka
Emika Panda robot used as a test platform. A reduction in terms of force
tracking error is achieved by deploying the proposed strategy, with a
short setup time.