A Prototype of a Novel Energy Efficient Variable Stiffness Actuator

Department of Electrical Engineering, Faculty of Electrical Engineering, Mathematics and Computer Science, University of Twente, 7500 AE Enschede, The Netherlands.
Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 08/2010; 2010:3703-6. DOI: 10.1109/IEMBS.2010.5627424
Source: IEEE Xplore


In this work, we present a proof of concept of a novel variable stiffness actuator. The actuator design is based on the conceptual design proposed in earlier work, and is such that the apparent output stiffness of the actuator can be changed independently of the output position and without any energy cost. Experimental results show that the behavior of the prototype is in accordance with the theoretical results of the conceptual design, and thus show that energy efficient variable stiffness actuators can be realized.

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    • "Section II presents a port-based model of a variable stiffness actuator. Using this model, conditions for energy efficiency of such an actuator is derived as in [4]. Section III presents the working principle of an energy efficient rotational actuator. "
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    ABSTRACT: This paper presents the working principle, the design and realization of a novel rotational variable stiffness actuator, whose stiffness can be varied independently of its output angular position. This actuator is energy-efficient, meaning that the stiffness of the actuator can be varied by keeping constant the internal stored energy of the actuator. The principle of the actuator is an extension of the principle of translational energy-efficient actuator vsaUT. A prototype based on the principle has been designed, in which ball-bearings and linear slide guides have been used in order to reduce losses due to friction.
    Full-text · Article · Aug 2011 · Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference
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    ABSTRACT: Variable stiffness actuators are a particular class of actuators that is characterized by the property that the apparent output stiffness can be changed independent of the output position. To achieve this, variable stiffness actuators consist of a number of elastic elements and a number of actuated degrees of freedom, which determine how the elastic elements are perceived at the actuator output. Changing the apparent output stiffness is useful for a broad range of applications, which explains the increasing research interest in this class of actuators. In this paper, a generic, port-based model for variable stiffness actuators is presented, with which a wide variety of designs can be modeled and analyzed. From the analysis of the model, it is possible to derive kinematic properties that variable stiffness actuator designs should satisfy in order to be energy efficient. More specifically, the kinematics should be such that the apparent output stiffness can be varied without changing the potential energy that is stored in the internal elastic elements. A concept design of an energy-efficient variable stiffness actuator is presented and implemented. Simulations of the model and experiments on the realized prototype validate the design principle.
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    ABSTRACT: It is crucial to have safely physical interaction between people and machines in versatile situations. In this paper, a new and efficient actuation robotic arm, continuous-state coupled elastic actuation (CCEA), is proposed to provide human-machine systems with an intrinsically programmable stiffness capacity to shape output force corresponding to the deviation between human motions and set positions of the system. The bond graph approach is used to analyze the variable stiffness property of the CCEA system, and the backstepping controller based on bond graph is employed to control the robotic arm. Finally, some experiments about controlling the CCEA robotic arm has been conducted and shown satisfactory results.
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