Expanding Foam as the Material for Fabrication, Prototyping and Experimental Assessment of Low-Cost Soft Robots With Embedded Sensing

Abstract

Fabricating robots from soft materials imposes major constraints on the integration and compatibility of embedded sensing, transmission, and actuation systems. Various soft materials present different challenges, but also new opportunities, for novel fabrication techniques, integrated soft sensors, and embedded actuators. For instance, extensive research on silicone elastomers has led to the development of soft sensors based on closed channels filled with liquid metal conductors, as well as corresponding fluidic actuators by pressurizing cavities within the body. In this paper, we present a novel approach to soft robot fabrication using soft expanding foam as the base material. While recent research points to elastic foams as a means to reduce material, manufacturing costs, and robot mass, they have not been explored much in the literature. This paper presents fabrication and prototyping techniques for developing low cost, custom-shaped soft robots from expanding polyurethane foam. We describe how to integrate user-defined routing points for transmission and actuation through cable-driven electrical actuation systems directly into the foam. Furthermore, we explore novel fabrication and prototyping techniques in order to build and integrate soft sensors into the foam substrate, which we demonstrate on soft robots varying in design complexity from a soft gripper to a soft "puppy".

Real2Sim

“…While we choose a markerbased approach due to its ease of use and availability, the theory presented so far would equally apply to motion data reconstructed from any other capture system, as long as an objective function on the simulation state can be written in terms of the collected data. One interesting material with recent applications in soft robotics [Somm et al 2019] is flexible polyurethane foam. In general this material is relatively cheap and easy to work with.…”

“…Finally, we show an application of our method to soft robotics design in Figure 1. We first fabricate a soft robot prototype from type-III foam using the technique described by [Somm et al 2019]. Then we capture short motion samples for this particular specimen and estimate material parameters for homogeneous Neohookean elasticity and Newtonian viscosity for a reasonably coarse mesh.…”

Underwater Soft Robot Modeling and Control With Differentiable Simulation

“…Starfish is fabricated by creating an inverse mould into which silicone foam (SomaFoam 25, SmoothOn) is cast. Silicone foam, a material widely used for soft robotic fabrication [32], has been chosen as it allows for rapid fabrication, shows elastic properties, and has natural buoyancy. The "muscle fibers" or tendons can then be routed into the soft structure along the bottom of each of the legs of Starfish.…”

Soft Robotics: A Review of Recent Developments of Pneumatic Soft Actuators

“…There is also a control system known as a Proportional-Integral-Derivative (PID) controller, which is a control loop mechanism that utilizes feedback to keep a constant variable. Due to the fact that the PID controller only impacts one variable other control methods have been tested [59] A PID can be part of the control system, but there needs to be more hardware that effectively communicates to the servo motors or solenoids that activate the open or closed loops [60,61].…”