Forward Dynamics Compliance Control (FDCC): A new approach to cartesian compliance for robotic manipulators

Abstract

Compliant end effectors in robotics are an important prerequisite for the field of object manipulation and environment interactions. However, current manipulators are usually stiff position-controlled systems, generating the need to add compliance. In this work, we present Forward Dynamics Compliance Control (FDCC), a new threefold control concept that realizes Cartesian compliance through combining Admittance, Impedance and Force Control into one control strategy. We close the control loop only through a force-torque sensor, allowing a system independent and decoupled configuration of the end effector compliance. As a key component in FDCC, we leverage forward dynamics simulations of a virtual model to directly map Cartesian inputs to joint control commands, leading to excellent stability in singularities. Experiments on three different robotic manipulators verify the key advantages of this approach.