CompAct™ Arm

Fig. 1 – The CompAct arm.

Compliance is a fundamental requisite for any robot that needs to perform human-machine interaction or more generally to directly interact with the external world. This is because the physical elasticity of the drives’ transmission system makes the robot to be able to automatically adapt itself to the environment it is interacting with still keeping the force exchange low, which is something that cannot be achieved with traditional heavy and stiff industrial manipulators.

Although compliance can effectively make the difference, from the engineering point of view it introduces also some side effects. It typically induces underdamped dynamics which deteriorate the stability margin and the accuracy of the robot (due to the induced oscillations and static deflections) and limits the bandwidth which can be set in the controlled system. These drawbacks are tackled in mammalians, which exhibit joint compliance, by the synergetic presence in their body of both compliance and physical damping. The properties of passive compliance and damping typical of biological joints explain why e.g. humans are able to safely interact and be robust during collision due to compliance while at the same time having the potential of achieving fast, smooth yet accurate motion thanks to physical damping.

The mentioned benefits introduced by damping motivated the design and development of the CompAct™ Arm, Fig. 1, i.e. a manipulator powered by actuators with intrinsic rich skills related to the synergetic combination of passive compliance and variable physical damping. To the authors knowledge this is the first robotic systems to exhibit these combined properties. We believe that such a system is step towards the achievement of functional performance of natural systems and particularly the human in terms of motion agility, safety, without compromising dynamic performance (motion speed), precision and smoothness.

Tech transfer / Entrepreneurial initiatives

Along with R&D activities, we are currently actively involved in tech transfer to turn this technology into a product. We are now doing fundraising and looking forward to enlarge the team accordingly with a business plan that the team developed. For any further info, contact Matteo Laffranchi

Related pages

Publications

• M. Laffranchi, N. G. Tsagarakis and D.G. Caldwell,"Analysis andDevelopment of a Semiactive Damping System", DOI10.1109/TMECH.2012.2184293, IEEE Transactions on Mechatronics,2012
• L. Chen, M. Garabini, M. Laffranchi, N. Kashiri, N. G. Tsagarakis, A. Bicchi and D.G. Caldwell, "Optimal Control for Maximizing Velocity of the CompAct™ Compliant Actuator", in the Proc. of International Conference on Robotics and Automation (ICRA) 2013.
• N. Kashiri, M. Laffranchi, N. G. Tsagarakis, I. Sardellitti and D.G. Caldwell, "Dynamic Modeling and Adaptable Control of the CompAct™ Arm", in the Proc. of IEEE International Conference on Mechatronics, (ICM), 2013.
• M. Laffranchi, L. Chen, N. G. Tsagarakis and D.G. Caldwell, "The Role of Physical Damping in Compliant Actuation Systems", in the Proc. of International Conference on Intelligent Robots and Systems, (IROS), 2012.
• M. Laffranchi, N. G. Tsagarakis and D.G. Caldwell, “CompAct™ arm: a Compliant Manipulator with Intrinsic Variable Physical Damping”, in the Proc. of Robotics, Science and Systems (RSS) 2012.
• M. Laffranchi, N. G. Tsagarakis and D.G. Caldwell, “A Compact Compliant Actuator (CompAct™) with Variable Physical Damping”, in the Proc. of International Conference on Robotics and Automation (ICRA) 2011.
• M. Laffranchi, N. G. Tsagarakis and D.G. Caldwell, “A Variable Physical Damping Actuator (VPDA) for Compliant Robotic Joints”, in the Proc. of International Conference on Robotics and Automation (ICRA) 2010.

Patents

• N. G. Tsagarakis , M. Laffranchi , Bram Vanderborght and D.G. Caldwell , "Attuatore rotante elastico, particolarmente per applicazioni robotiche, e metodo per il suo controllo", Italian Patent TO2010A000257
• N. G. Tsagarakis , M. Laffranchi , Bram Vanderborght and D.G. Caldwell, "Elastic rotary actuator, particularly for robotic applications, and method for its control", United States Patent Application US 2010/0253273 A1
• N. G. Tsagarakis , M. Laffranchi , Bram Vanderborght and D.G. Caldwell, "Elastic rotary actuator, particularly for robotic applications, and method for its control", European Patent Application EU 10158648
• M. Laffranchi, N. G. Tsagarakis and D.G. Caldwell "Attuatore rotante elastico, particolarmente per applicazioni robotiche con dispositivo di smorzamento semi-attivo" Italian Patent TO2010A000360.
• M. Laffranchi, N. G. Tsagarakis and D.G. Caldwell "Elastic rotary actuator, particularly for robotic applications, provided with semi-active damping device"  International Patent PCT/IB2011/051877.