Design and Stiffness Evaluation of a Compliant Joint with Parallel Architecture Realizing an Approximately Spherical Motion

Abstract

This paper introduces the design of a fully-compliant Spherical Joint (SJ), obtained by the in-parallel connection of two identical open chains each composed of three equal circular flexible beams, having coincident centers of curvature and mutually orthogonal axes of minimum rotational stiffness. Thanks to its particular topology, the SJ provides a fully isotropic behavior, the two chains being placed in space so as to be symmetric with respect to the beams' center of curvature. At first, the overall system compliance matrix is derived by means of an analytical procedure, in order to obtain a parametric formulation of the SJ behavior within the small deflection range. Then, after finite element validation of the analytical model, an optimization study of the beam geometry is developed, with the aim of maximizing the ratio between the SJ primary to secondary compliance factors. At last, the potential advantages and drawbacks of the proposed design are discussed by numerically evaluating the joint performance in terms of parasitic motions within the large deflection range (namely, when large external loads are applied to the envisaged center of spherical motion).

Numerical simulation and statistical analysis of a cascaded flexure hinge for use in a cryogenic working environment

“…In contrast to cohesive joints with only one area of concentrated flexibility or with multi-unit flexible coupling mechanisms, the structural and dimensional synthesis of complex flexure pivots has not yet been discussed in detail. The literature mainly describes constructions with concentrated cross-section reductions in rectangular or circular contours, as well as the effect of these contours on the achievable range of motion [5][6][7][8][9][10][11][12][13][14][15][16][17]. There is also work on the geometric design of complex swivel joints on the basis of interlinked tape spring joints [18], which allow large angular deflections.…”

Towards Robust and Effective Passive Compliance Design of End-Effectors for Robotic Train Fluid Servicing

“…The pioneering work in manufacturing PiH assembly [16,17] discusses compliant wrists with RCC, accommodating certain misaligned shaft-bearing (PiH) insertions. Compliance in other robotics, actuators, joints [18,19], or manipulators [20,21], absorb unexpected crashes and improve safety. Compliant and soft grippers adapt to a range of object shapes or provide gripping despite misalignments [22][23][24].…”

“…Beyond these specific issues with the PiH problem, we have noticed another more general pattern across the literature on passive compliance devices [16][17][18][19][20][21][22][23][24][25][26][27][28]. The structure of papers follows a common approach where, due to a specific problem, a compliant mechanism is synthesised, modelled, and analysed to showcase its performance for the intended task.…”