An Engineering Method for Comparing Selectively Compliant Joints in Robotic Structures

Abstract

Large displacement compliant joints can substitute traditional kinematic pairs in robotic articulated structures for increasing ease-of-assembly, robustness, and safety. Nonetheless, besides their limited motion capabilities, compliant joints might be subjected to undesired spatial deformations which can deteriorate the system stability and performance whenever a low number of control inputs is available. In all these cases, it is convenient to select/design joint morphologies which enable a selectively compliant behavior, i.e., a low stiffness along a single desired direction. Within this context, this paper outlines an engineering method for quantifying the joint's selective compliance by means of local and global performance indices. The approach is validated by comparing two beam-like flexures whose analytic solution is known from the literature. Finally, two joint morphologies, previously employed in the fabrication of robotic/prosthetic hands, are critically compared on the basis of the proposed criteria

Conceptual design and virtual prototyping of a wearable upper limb exoskeleton for assisted operations

“…For instance, Fig. 6c shows a possible configuration of compliant balancer, namely a flexible beam whose shape is to be optimized in order to match a specific, pre-defined, force-deflection behavior (F b = F b (θ )) in the angular range of interest [69][70][71].…”

Compliant Cross-Axis Joints: A Tailoring Displacement Range Approach via Lattice Flexures and Machine Learning

“…Additionally, other works where the main objective was the development of optimal robotic members are also reported in the literature. For example, a three-degrees-of-freedom robotic arm with compliant fingers [12], the design of a compliant finger for a 3D endoskeleton with soft matter [13], the development of an engineering method for quantifying the CJ compliance of robotic hands [14], and the design of soft monolithic robotic fingers for prosthetic hands [5]. In the field of MEMSs, CJs have been widely used and tested, resulting in progress for medical devices and precision engineering applications.…”

Toward unibody robotic structures with integrated functions using multimaterial additive manufacturing: Case study of an MRI-compatible interventional device

“…Several works about analysis tools and methods exist for the synthesis or improvement of a compliant joint. The analysis of the joint compliance matrix is an efficient way to assess the existence of undesired parasitic motions [9], [10]. For a revolute joint, one issue is the comparison of translational and rotational compliances.…”

“…For a revolute joint, one issue is the comparison of translational and rotational compliances. Normalization techniques [9] have been proposed to solve this issue. After such a normalization, one efficient approach for joint design is parametric analysis with design charts to determine the impact of joint design parameters [10].…”