This paper presents the design of a two-degrees-of-freedom (DoFs) variable stiffness mechanism and demonstrates how its adjustable compliance can enhance the robustness of physical human–robot interaction. Compliance on the grasp handle is achieved by suspending it in between magnets in preloaded repelling configuration to act as nonlinear springs. By adjusting the air gaps between the outer magnets, the stiffness of the mechanism in each direction can be adjusted independently. Moreover, the capability of the proposed design in suppressing unintended interaction forces is evaluated in two different experiments. In the first experiment, improper admittance controller gain leads to unstable interaction, whereas in the second case, high-frequency involuntary forces are caused by the tremor.
Variable Stiffness Mechanism for Suppressing Unintended Forces in Physical Human–Robot Interaction
Contributed by the Mechanisms and Robotics Committee of ASME for publication in the JOURNAL OF MECHANISMS AND ROBOTICS. Manuscript received October 16, 2018; final manuscript received December 12, 2018; published online February 27, 2019. Assoc. Editor: Pierre M. Larochelle.
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Jujjavarapu, S. S., Memar, A. H., Karami, M. A., and Esfahani, E. T. (February 27, 2019). "Variable Stiffness Mechanism for Suppressing Unintended Forces in Physical Human–Robot Interaction." ASME. J. Mechanisms Robotics. April 2019; 11(2): 020915. https://doi.org/10.1115/1.4042295
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