Energy-Efficient Variable Stiffness Actuators.

IEEE Transactions on Robotics 01/2011; 27:865-875.
Source: DBLP

ABSTRACT Variable stiffness actuators realize a particular class of actuators characterized by the property that the apparent output stiffness can be changed independently of the output position. This is feasible due to the presence of internal springs and internal actuated degrees of freedom. In this work, we establish a port-based model of variable stiffness actuators and we derive an energy efficient control strategy. In particular, when the variable stiffness actuator acts on a mechanical system, the internal degrees of freedom are used to achieve the desired nominal behavior and the internal springs are used as a potential energy buffer. The release of energy from the springs, as well as the apparent output stiffness, are regulated by control of the internal degrees of freedom. Simulation results on a robotic joint illustrate the effectiveness of the control strategy during the tracking of a periodic motion in presence of disturbances.

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    ABSTRACT: Research effort in the field of variable stiffness actuators is steadily increasing, due to their wide range of possible applications and their advantages. In literature, var- ious control methods have been proposed, solving particular problems in human-robot and robot-environment interaction applications, in which the mechanical compliance introduced by variable stiffness actuators has been shown to be beneficial. In this work, we focus on achieving energy efficient actuation of robotic systems using variable stiffness actuators. In particular, we aim to exploit the energy storing properties of the internal elastic elements.


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