Session: MR-03-02 - Compliant Mechanisms (A. Midha Symposium)

Paper Number: 89903

89903 - A Neutrally Stable Quasi-Compliant Spherical Joint With a Remote Center of Rotation 

This paper presents the design of a compliant spherical joint which is neutrally stable in two DoF and has a remote center of rotation. Such a joint can be used, for example, as an exoskeleton's shoulder joint. The foundation of this paper lies in previous work that has succeeded in designing a compliant spherical joint with a remote center of rotation, but without neutral stability. The existing joint is first simulated and its energy properties are analysed and visualized in the form of an energy field. This energy field shows the energy magnitude as a function of the two rotational DoF that are to be made neutrally stable. In order to achieve neutral stability, the energy field must be constant within its range of motion. This can be achieved by the addition of a spring that has a mirrored energy field relative to the joint, such that their combined energy field would be constant within the range of motion. For better neutral stability performance, the joint is first optimized for axi-symmetry in its energy field. Thereafter, the spring is optimized such that the combined energy field of both spring and joint, is neutrally stable. Experimental verification of the simulation was achieved with a prototype for which a moment reduction of 83.69% was achieved through the addition of the spring.

Presenting Author: Just Herder TU Delft

Presenting Author Biography: Just Herder is a full professor of Interactive Mechanisms and Mechatronics, Chair of the Mechatronic System Design group and Head of Department of Precision and Microsystems Engineering at Delft University of Technology.<br/><br/>He has widely published in international peer-reviewed journals and conferences and has received several international awards. He is an ASME fellow, board member of several international conferences, associate editor of Mechanism and Machine Theory, and co-founder of Mechanical Sciences. Seven start-up companies have emerged from his research and he holds over a dozen international patents in different areas of mechanism design. He held visiting positions at Laval University, Canada, and at MIT, USA, as a Fulbright Visiting Scholar.

Authors:

Dion Hogervorst TU Delft
Giuseppe Radaelli TU Delft
Just Herder TU Delft