# Single-Input Control of Multiple Fluid-Driven Elastic Actuators Via Interaction Between Bi-Stability and Viscosity

## TL;DR

This paper introduces a novel method for controlling multiple bi-stable elastic chambers in soft robotics using a single input flow rate, leveraging bi-stability and viscosity effects to achieve complex state transitions.

## Contribution

The work presents a new control technique that simplifies soft actuator operation by inducing irreversible state transitions through pressure lag and bi-stability, demonstrated with simulations and experiments.

## Key findings

- Successful control of up to 5 chambers with a single input.
- Transitions enabled by bi-stability and viscous pressure lag.
- Potential for minimalistic control in soft robotics applications.

## Abstract

A leading concept in soft robotics actuation, as well as in microfluidics applications such as valves in lab-on-a-chip devices, is applying pressurized flow in cavities embedded within elastic bodies. Generating complex deformation patterns typically requires control of several inputs, which greatly complicates the system's operation. In this work, we present a novel method for single-input control of a serial chain of bi-stable elastic chambers connected by thin tubes. Controlling a single flow rate at the chain's inlet, we induce an irreversible sequence of transitions that can reach any desired state combination of all bi-stable elements. Mathematical formulation and analysis of the system's dynamics reveal that these transitions are enabled thanks to bi-stability combined with pressure lag induced by viscous resistance. The results are demonstrated via numerical simulations combined with experiments for chains of up to 5 chambers, using water-diluted glycerol as the injected fluid. The proposed technique has a promising potential for development of sophisticated soft actuators with minimalistic control.