Monolithic Units: Actuation, Sensing, and Simulation for Integrated Soft Robot Design

TL;DR

This paper presents the Monolithic Unit, a unified soft robotic component integrating actuation, sensing, and simulation, enabling scalable, reproducible design and embedded sensing through a combined fabrication and optimization workflow.

Contribution

It introduces a novel monolithic design framework for soft robots that unifies actuation, sensing, and simulation in a scalable, reproducible manner.

Findings

Validated mechanical performance of optimized units

Embedded sensing preserved mechanical response

Demonstrated scalability with a two-finger gripper

Abstract

This work introduces the Monolithic Unit (MU), an actuator-lattice-sensor building block for soft robotics. The MU integrates pneumatic actuation, a compliant lattice envelope, and candidate sites for optical waveguide sensing into a single printed body. In order to study reproducibility and scalability, a parametric design framework establishes deterministic rules linking actuator chamber dimensions to lattice unit cell size. Experimental homogenization of lattice specimens provides effective material properties for finite element simulation. Within this simulation environment, sensor placement is treated as a discrete optimization problem, where a finite set of candidate waveguide paths derived from lattice nodes is evaluated by introducing local stiffening, and the configuration minimizing deviation from baseline mechanical response is selected. Optimized models are fabricated and experimentally characterized, validating the preservation of mechanical performance while enabling embedded sensing. The workflow is further extended to scaled units and a two-finger gripper, demonstrating generality of the MU concept. This approach advances monolithic soft robotic design by combining reproducible co-design rules with simulation-informed sensor integration.