Modular Hybrid Robots for Safe Human-Robot Interaction

The paper considers a novel modular and intrinsically safe redundant robotic system with biologically inspired actuators (pneumatic artificial muscles and rubber bellows actuators). Similarly to the biological systems, the stiffness of the internal parallel modules, representing 2 DOF joints in the serial robotic chains, is controlled by co-activation of opposing redundant actuator groups in the null-space of the module Jacobian, without influencing the actual robot position. The decoupled position/stiffness control allows the realization of variable joint stiffness according to different force-displacement relationships. The variable joint stiffness, as well as limited pneumatic muscle/bellows force ability, ensures internal system safety that is crucial for development of human-friendly robots intended for human-robot collaboration. The initial experiments with the system prototype demonstrate the capabilities of independently, simultaneously controlling both joint (Cartesian) motion and joint stiffness. The paper also presents the possible industrial applications of snake-like robots built using the new modules.

• J. Radojicic
• D. Surdilovic
• G. Schreck

• bellows actuator
• human-robot interaction
• hyper redundant robot
• pneumatic muscle.

[1] Vukobratović M., Surdilović D., Ekalo Y., Katic D., Dynamics and
Robust Control of Robot-Environment Interaction, World-Scientific,
New-Jersey, 2009.
[2] Chiaverrini S., Siciliano B., Villani L., 1999, A Survey of Robot
Interaction Control Schemes with Experimental Comparison,
IEEE/ASME Trans. on Mechatronics, Vol. 4, No. 3, 273-285.
[3] Sami Haddadin, Alin Albu-Schäffer and Gerd Hirzinger: The Role of the
Robot Mass and Velocity in Physical Human-Robot Interaction - Part I:
Unconstrained Blunt Impacts, IEEE Int. Conf. on Robotics and
Automation (ICRA 2008), Pasadena, USA, 2008.
[4] Dongjun Shin, Irene Sardeliti and Oussama Khatib:A Hybrid Actuation
Approach for Human-Friendly Robot Design, IEEE Int. Conf. on
Robotics and Automation (ICRA 2008), Pasadena, USA, 2008.
[5] Albu-Schäfer A., Eiberger O., Grebenstein M., Haddadin S., Ott C.,
Wimböck T., Wolf S. and Hirzinger G., : ÔÇ×Soft Robotics", IEEE
Robotics & Automation Magazine, September 2008, pp. 20-26.
[6] Bicchi A., Tonnieti G., "Fast and "Soft-Arm" Tactics", IEEE
Robotics&Automation Magazine, June 2004, pp.22-33.
[7] J. P. Merlet, Parallel Robots (Solid mechanics and its Applications),
2end ed., Springer-Verlag, 2006.
[8] B. Tondu, V. Boitier, P. Lopez. Natural compliance of robot-arms based
on McKibben artificial muscle actuators. In European Robotics and
Intelligent Systems Conference, pp. 783-797, Malaga, 1994.
[9] Daerden F., Conception and Realization of Pleated Pneumatic Artificial
Muscles and Their Use as Compliant Actuation Elements, PhD. Thesis,
Vrije, Universiteit Brussel, 1999.
[10] Radojicic J., Surdilovic D. and Kr├╝ger J., "Control Algorithms of
Pneumatic-Muscles Actuators in Complex Mechanical Chains", CD
Proc. III Int. Symp. on Adaptive Motion in Animals and Machines,
AMAM-2005, Sep. 2005, Ilmenau, Germany, Abs. pp 44.