Open Access Open Access  Restricted Access Subscription Access


Luc Tien Le


This paper presents a control structure for orbital servicing mission of CEASAR robotic arm developed by German Aerospace Center (DLR). In order to reduce mass the CEASAR arm is equipped with Harmonic-Drives with high ratio which unfortunately lead to high joint elasticity and high motor friction and have to be considered in controller design for successful manipulator in-orbit operations. Therefore, in this control structure, for high tracking control a cascaded position controller based on state feedback control structure with observer-based friction compensation and for safe interaction control with the environment a Cartesian impedance controller is used. The proposed control methods are very efficient and practicable. Furthermore, they are very robust with dynamic parameter uncertainties, coupling dynamics, and can simultaneously provide good results in term of the position accuracy and dynamic behavior. Simulation results validate practical efficiency of the controllers.


Impedance control, floating base robots, space robots, flexible joint robots

Full Text:



B. Schäfer, K. Landzettel, A. Albu-Schäffer, G. Hirzinger. “ROKVISS: Orbita l Testbed for Tele-Presence Experiments, Novel Robotic Components and Dynamics Models Verification”, Proc. 8th ESA Workshop on Advanced Space Technologies for Robotics and Automation (ASTRA), Noordwijk, November, 2004

B. Schäfer, B. Rebele, K. Landzettel, “ROKVISS - Space Robotics Dynamics and Control Performance Experiments at the ISS”. Proc. ACA 2004 IFAC Symposium on Automatic Control in Aerospace, St. Petersburg, pp.333-338, June 2004.

N. Hogan. “Impedance control: An approach to manipulation: Parts I, II, and III-theory, implementation, and applications”. Journal of Dynamic Systems Measurement, and Control, 107: 1-24, 1985.

Khatib. “A unified approach for motion and force control of robot manipulators: The operational space formulation”. IEEE Journal of Robotics and Automation, 3: 1115-1120, 1987.

Y. Umetami and K. Yoshida. “Resolved motion rate control of space manipulators with generalized Jacobian matrix”. IEEE Transactions on Robotics and Automation, 5(3), June 1989.

Y. Xu and T. Kanade. ”Space Robotics: Dynamics and Control”. Prentice Hall, 1992.

S. Abiko and G. Hirzinger. „Adaptive Control for a Torque Controlled Free-Floating Space Robot with Kinematic and Dynamic Model Uncertainty”. IEEE/RSJ International Conference on Intelligent Robots and Systems, 2009.

C. Ott. Cartesian impedance control of redundant and flexible-joint robots. Dissertation, Saarland University, 2005.

F. Ferraguti, C. Secchi and C. Fantuzzi. “A tank-based approach to impedance control with variable stiffness”, IEEE International Conference on Robotics and Automation, p. 4948-4953, 2013.

M. Franken, S. Stramigioli, S. Misra, C. Secchi, and A. Macchelli, “Bilateral telemanipulation with time delays: A two-layer approach combining passivity and transparency,” IEEE Trans. Robot., vol. 27, no. 4, pp. 741–756, Aug. 2011.

Franchi, C. Secchi, H. I. Son, H. H. Bülthoff, and P. R. Giordano, “Bilateral telemanipulation of groups of mobile robots with timevarying topology,” IEEE Trans. Robot., vol. 28, no. 5, pp. 1019–1033, Oct. 2012.

Albu-Schäffer, C. Ott, and G. Hirzinger. “A unified passivity- based control framework for position, torque and impedance control of flexible joint robots”. The Int. Journal of Robotics Research, pages 23–39, 2007.

L. Tian and A.A. Goldenberg. Robust adaptive control of flexible joint robots with joint torque feedback. IEEE International Conference on Robotics and Automation, pages 1229–1234, 1995.

Le-Tien, A. Albu-Schäffer, A. De Luca, G. Hirzinger. „Friction Observer and Compensation for Control of Robots with Joint Torque Measurement”. IEEE/RSJ International Conference on Intelligent Robots and Systems, 2008.


Journal of Computer Science and Cybernetics ISSN: 1813-9663

Published by Vietnam Academy of Science and Technology