Design and Kinematic Analysis of the Novel Almost Spherical Parallel Mechanism Active Ankle

Shivesh Kumar; Bertold Bongardt; Marc Simnofske; Frank Kirchner
In: Journal of Intelligent & Robotic Systems (JIRS), Vol. n.n. No. 1573-0409, Pages 1-23, Springer Nature, 3/2018.


The novel mechanism Active Ankle features three degrees of freedom that operate in an almost spherical manner. In comparison to spherical devices, its design offers advantages such as high stiffness, a simple and robust construction, and a good stress distribution. In the present paper, a comprehensive study of the design, analysis, and control of the Active Ankle in its almost-spherical work modality is provided. In particular, the kinematic analysis of the mechanism is conducted, solving the full inverse, the rotative inverse, and the forward kinematic problems. In addition, the manipulator's workspace is characterized and the kinematic control, that has been implemented on a prototype of Active Ankle, is presented together with experimental results that demonstrate the employability as an ankle joint in a full body exoskeleton.

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