A soft unmanned underwater vehicle with augmented thrust capability

The components which could make Soft Unmanned Underwater Vehicles a winning technology for a range of marine operations are addressed: these include vortex-enhanced thrust, added mass recovery and high degree of compliance of the vehicle. Based on these design criteria and recent advancement in soft-bodied, pulsed-jet thrusters, a new underwater vehicle is developed and tested

Cephalopod-inspired soft robots: design criteria and modelling frameworks

Cephalopods (i.e. octopuses and squids) are taken as a source of inspiration for the development of a new kind of underwater soft robot. These cephalopod-inspired, soft-bodied vehicles entail a hollow, elastic shell capable of performing a routine of recursive ingestion and expulsion of discrete slugs of fluids via the actual inflation and deflation of the elastic chamber. This routine allows the vehicle to propel itself in water in a very similar fashion to that of cephalopods. This mode of pulsed jetting enabled by the actual body shape variations can ideally benefit from the positive feedback provided by impulse-rich discontinuous jet formation and added mass recovery. This work is complemented by extensive modelling efforts which are meant to aid in the process of mechanical design optimization as well as providing an advanced tool for biomechanical studies of living cephalopods

Forward speed control of a pulsed-jet soft-bodied underwater vehicle

This paper reports on the development of the control for a new class of soft underwater vehicles. These vehicles exploit their soft-bodied nature to produce thrust by cyclically ingesting and expelling ambient fluid. A forward speed control based on the linearised dynamics of the robot is design. The control succeeds at dealing with the discontinuous thrust by accounting for the shape-change driven actuation

Evolving soft locomotion in aquatic and terrestrial environments: effects of material properties and environmental transitions

Designing soft robots poses considerable challenges: automated design approaches may be particularly appealing in this field, as they promise to optimize complex multi-material machines with very little or no human intervention. Evolutionary soft robotics is concerned with the application of optimization algorithms inspired by natural evolution in order to let soft robots (both morphologies and controllers) spontaneously evolve within physically-realistic simulated environments, figuring out how to satisfy a set of objectives defined by human designers. In this paper a powerful evolutionary system is put in place in order to perform a broad investigation on the free-form evolution of walking and swimming soft robots in different environments. Three sets of experiments are reported, tackling different aspects of the evolution of soft locomotion. The first two sets explore the effects of different material properties on the evolution of terrestrial and aquatic soft locomotion: particularly, we show how different materials lead to the evolution of different morphologies, behaviors, and energy-performance tradeoffs. It is found that within our simplified physics world stiffer robots evolve more sophisticated and effective gaits and morphologies on land, while softer ones tend to perform better in water. The third set of experiments starts investigating the effect and potential benefits of major environmental transitions (land - water) during evolution. Results provide interesting morphological exaptation phenomena, and point out a potential asymmetry between land-water and water-land transitions: while the first type of transition appears to be detrimental, the second one seems to have some beneficial effects.Comment: 37 pages, 22 figures, currently under review (journal

PoseiDRONE: design of a soft-bodied ROV with crawling, swimming and manipulation ability

The design concept and development of a multi-purpose, underwater robot is presented. The final robot consists of a continuum composed for 80% of its volume of rubber-like materials and it combines locomotion (i.e. crawling and swimming) and manipulation capabilities. A first prototype of the robot is illustrated based on the integration of existing prototypes

Model Predictive Wave Disturbance Rejection for Underwater Soft Robotic Manipulators

Inspired by the octopus and other animals living in water, soft robots should naturally lend themselves to underwater operations, as supported by encouraging validations in deep water scenarios. This work deals with equipping soft arms with the intelligence necessary to move precisely in wave-dominated environments, such as shallow waters where marine renewable devices are located. This scenario is substantially more challenging than calm deep water since, at low operational depths, hydrodynamic wave disturbances can represent a significant impediment. We propose a control strategy based on Nonlinear Model Predictive Control that can account for wave disturbances explicitly, optimising control actions by considering an estimate of oncoming hydrodynamic loads. The proposed strategy is validated through a set of tasks covering set-point regulation, trajectory tracking and mechanical failure compensation, all under a broad range of varying significant wave heights and peak spectral periods. The proposed control methodology displays positional error reductions as large as 84% with respect to a baseline controller, proving the effectiveness of the method. These initial findings present a first step in the development and deployment of soft manipulators for performing tasks in hazardous water environments.Comment: To be presented at RoboSoft 2024, San Dieg

PoseiDRONE: design of a soft-bodied ROV with crawling, swimming and manipulation ability

The design concept and development of a multi-purpose, underwater robot is presented. The final robot consists of a continuum composed for 80% of its volume of rubber-like materials and it combines locomotion (i.e. crawling and swimming) and manipulation capabilities. A first prototype of the robot is illustrated based on the integration of existing prototypes