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LabsHumanoids & Human Centred MechatronicsProjects ■ Chobin Jumping Robot

Compliant Actuation - Chobin Jumping Robot



The MACCEPA (Mechanically Adjustable Compliance and Controllable Equilibrium Position Actuator) is an electric actuator of which the compliance and equilibrium position are fully independently controllable and both are set by a dedicated servomotor. This actuator has been developed by the Vrije Universiteit Brussel (VUB). In collaboration with the VUB, IIT has developed an improvement of the actuator where the torque-angle curve and consequently the stiffness-angle curve can be modified by choosing an appropriate shape of a profile disk, which replaces the lever arm of the former design. The actuator has a large joint angle, torque and stiffness range and these properties can be made beneficial for safe human robot interaction and the construction of energy efficient walking, hopping and running robots.

Working principle of the novel MACCEPA 2.0. Above: Out of equilibrium position (generating torque)

equilibrium-position-no-torque changed-pretension
equilibrium position (not generating torque) Changed pretension

Comparison of torque-angle curve of MACCEPA 1.0 (thin line) and MACCEPA 2.0 (bold line) at different pretensions P.
Comparison of stiffness-angle curve of MACCEPA 1.0 (thin line) and MACCEPA 2.0 (bold line) at different pretensions P.


The ability to store and release energy is shown by simulations on a 1DOF hopping robot. Its hopping height is much higher compared to a configuration in which the same motor is used in a traditional stiff setup. The stiffness of the actuator has a stiffening characteristic so the leg stiffness resembles more a linear stiffness as found in humans. By controlling the equilibrium position and pretension different hopping heights and frequencies are obtained. Currently the hopping robot Chobino is under construction to validate these simulations.

Last Updated on Monday, 16 April 2012 13:41


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