Mechanical Characterization of Compliant Cellular Robots. Part II: Active Strain

TL;DR

This paper uses finite element analysis to explore the active strain behavior of MACRO mesh structures, revealing how topology and actuator orientation influence deformation and actuation effort in compliant cellular robots.

Contribution

It provides a detailed FEA-based analysis of active strain characteristics in MACRO meshes, highlighting the effects of topology and actuator configuration on deformation and effort.

Findings

Actuation modes can induce size-independent deformation.

A subset of actuation modes spans the deformation range.

Actuation effort correlates with mesh nodal connectivity.

Abstract

Modular Active Cell Robots (MACROs) is a design approach in which a large number of linear actuators and passive compliant joints are assembled to create an active structure with a repeating unit cell. Such a mesh-like robotic structure can be actuated to achieve large deformation and shape-change. In this two-part paper, we use Finite Element Analysis (FEA) to model the deformation behavior of different MACRO mesh topologies and evaluate their passive and active mechanical characteristics. In part 1, we presented the passive stiffness characteristics of different MACRO meshes. Now, in this part 2 of the paper, we investigate the active strain characteristics of planar MACRO meshes. Using FEA, we quantify and compare the strains generated for the specific choice of MACRO mesh topology and further for the specific choice of actuators actuated in that particular mesh. We simulate a series of actuation modes that are based on the angular orientation of the actuators within the mesh and show that such actuation modes result in deformation that is independent of the size of the mesh. We also show that there exists a subset of such actuation modes that spans the range of deformation behavior. Finally, we compare the actuation effort required to actuate different MACRO meshes and show that the actuation effort is related to the nodal connectivity of the mesh.