Continuum Differential Mechanisms and Their Applications in Gripper Designs

Differential mechanisms possess various forms and are applied in a wide spectrum of mechanical systems. This paper proposes to categorize differential mechanisms into kinematic differential mechanisms (KDMs) and continuum differential mechanisms (CDMs), and also introduces two CDMs. The working principle, structures, constructions, and kinetostatic analyses of the proposed planar and the spatial CDMs are elaborated upon. The planar CDM is compared with two widely used differential mechanisms made from pulleys and linkages to show its effectiveness using a simple construction. The spatial CDM could resolve one input into three outputs in a way different from two serially connected planar differential mechanisms. As demonstrated in experimentation, the spatial CDM could allow more isotropic distribution of the three outputs. The categorization, analyses, and applications of the CDMs might not only extend the IFToMM terminology on differential mechanisms, but also inspire more CDM designs with distinct responses and properties for adaptive mechanical systems.