Abstract
The inherent compliant and safe structure of fluid driven continuum manipulators makes them a promising solution for various tasks. Despite their cheap production costs these robots have yet not found their way into industrial applications. This is due to the lack of precise models as well as control strategies which are both open fields of research.
A basic industrial task is to control the force the manipulator exerts at its tool center point on a given object. In this work we present a hybrid force/position controller (HFPC) for the Bionic Soft Arm (BSA). It is assumed that contact is only established at the tool center point where the contact force can be measured. Further, we show how to extend the basic HFPC approach in order to overcome model inaccuracies. Experimental results are provided for the BSA where the HFPC is incorporated into an existing structure.
Zusammenfassung
Mit ihren inhärent nachgiebigen und damit sicheren Strukturen stellen fluidgetriebene Kontinuum-Manipulatoren eine vielversprechende Lösung für verschiedenste Aufgaben dar. Trotz ihrer günstigen Herstellungskosten werden diese Roboter bis jetzt nicht für industrielle Zwecke genutzt. Der Grund dafür sind unpräzise Modelle sowie mangelhafte Regelstrategien, wobei an beidem derzeit aktiv geforscht wird.
Eine grundlegende Aufgabe in der Produktion ist die Regelung der Kraft, welche ein Manipulator an seinem Werkzeugpunkt auf ein gegebenes Objekt ausüben soll. In dieser Arbeit wird eine Lösung für den Bionic Soft Arm (BSA) vorgestellt, welche auf einer hybriden Kraft-/Positionsregelung (HFPC) basiert. Es wird angenommen, dass der Kontaktfall nur am Werkzeugpunkt auftritt, wo die anliegende Kraft gemessen werden kann. Darüber hinaus wird gezeigt, wie der grundlegende hybride Kraft-/Positionsreglungsansatz angepasst werden muss, um die gegebenen Modellunsicherheiten zu überwinden. Es werden experimentelle Ergebnisse am BSA präsentiert, wobei der vorgeschlagene Regelansatz in eine bereits existierende Struktur integriert wird.
Funding source: Deutsche Forschungsgemeinschaft
Award Identifier / Grant number: SA 847/20-1
Funding statement: The authors gratefully acknowledge funding of this work by the German Research Foundation (DFG) under grant SA 847/20-1.
About the authors
Daniel Müller received his M.Sc. degree in Engineering Cybernetics from the University of Stuttgart, Germany, in 2018. Since spring 2018, he has been a Research Assistant with the Institute for System Dynamics, University of Stuttgart, Germany. His research interests include continuum manipulators, machine learning and optimization.
Carina Veil received her B.Sc. degree in Medical Engineering from the University of Stuttgart, Germany, in 2017. She is currently a student and will receive her M.Sc. degree in Engineering Cybernetics in 2020. Since spring 2019 she has been a student assistant at the Institute for System Dynamics, University of Stuttgart, where she supports Daniel Müller in the research field of continuum manipulators.
Oliver Sawodny received the Dipl.-Ing. degree in electrical engineering from the University of Karlsruhe, Karlsruhe, Germany, in 1991, and the Ph.D. degree from the Ulm University, Ulm, Germany, in 1996. In 2002, he became a Full Professor with the Technical University of Ilmenau, Germany. Since 2005, he has been the director of the Institute for System Dynamics, University of Stuttgart, Stuttgart, Germany. His current research interests include methods of differential geometry, trajectory generation, and applications to mechatronic systems.
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