Programming active cohesive granular matter with mechanically induced phase changes

Li, Shengkai; Dutta, Bahnisikha; Cannon, Sarah; Daymude, Joshua J.; Avinery, Ram; Aydın, Enes; Richa, Andréa W.; Goldman, Daniel I.; Randall, Dana

doi:10.1126/sciadv.abe8494

Cited by 33 publications

(22 citation statements)

References 56 publications

(63 reference statements)

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“…Swarm robotics (1-4) uses a multitude of simple robots, with minimal ingredients (such as self-locomotion or simple configurational change) leading, through mutual interactions (5)(6)(7), to global organization with abilities that may go beyond those of the individual particles (6)(7)(8)(9)(10)(11). Different types of robots have been proposed to achieve this goal, from motile vibrating bots and active particles with embedded locomotion to shape-changing and/or light-sensitive particles (6)(7)(8)(9)(10)12).…”

Section: Introductionmentioning

confidence: 99%

From collections of independent, mindless robots to flexible, mobile, and directional superstructures

et al. 2021

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A swarm of simple active particles confined in a flexible scaffold is a promising system to make mobile and deformable superstructures. These soft structures can perform tasks that are difficult to carry out for monolithic robots because they can infiltrate narrow spaces, smaller than their size, and move around obstacles. To achieve such tasks, the origin of the forces the superstructures develop, how they can be guided, and the effects of external environment, especially geometry and the presence of obstacles, need to be understood. Here, we report measurements of the forces developed by such superstructures, enclosing a number of mindless active rod-like robots, as well as the forces exerted by these structures to achieve a simple function, crossing a constriction. We relate these forces to the self-organization of the individual entities. Furthermore, and based on a physical understanding of what controls the mobility of these superstructures and the role of geometry in such a process, we devise a simple strategy where the environment can be designed to bias the mobility of the superstructure, giving rise to directional motion. Simple tasks—such as pulling a load, moving through an obstacle course, or cleaning up an arena—are demonstrated. Rudimentary control of the superstructures using light is also proposed. The results are of relevance to the making of robust flexible superstructures with nontrivial space exploration properties out of a swarm of simpler and cheaper robots.

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Section: Introductionmentioning

confidence: 99%

From collections of independent, mindless robots to flexible, mobile, and directional superstructures

et al. 2021

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“…Study of active systems on elastic fields and the differential geometry framework could thus function as a model system and provide tools to robotic studies ( 12 , 68 – 71 ) of a broader class of physical ( 72 , 73 ) systems. For instance, the local curvature could be used as an input in addition to other information such as vision ( 6 , 74 , 75 ) and stress sensing ( 14 , 60 , 76 ) in swarm robotics. Curvature field information could be exploited by robots with limited sensing and control, for example, in lightweight water-walking robots ( 70 , 77 ) or self-propelled microrobots ( 78 ) swarming on fluid membranes ( 79 ).…”

Section: Discussionmentioning

confidence: 99%

“…We note that such a strategy is interesting because the robots could avoid (or potentially enhance) aggregation solely via local field measurements alone. Such dynamics could be useful for future swarms of sensory-challenged robots ( 60 ) moving on highly deformable environments.…”

Section: Using Speed’s Response To Tilt To Avoid Merger Of Two Vehiclesmentioning

confidence: 99%

Field-mediated locomotor dynamics on highly deformable surfaces

Ozkan-Aydin

Small

et al. 2022

Proc. Natl. Acad. Sci. U.S.A.

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Studies of active matter—systems consisting of individuals or ensembles of internally driven and damped locomotors—are of interest to physicists studying nonequilibrium dynamics, biologists interested in individuals and swarm locomotion, and engineers designing robot controllers. While principles governing active systems on hard ground or within fluids are well studied, another class of systems exists at deformable interfaces. Such environments can display mixes of fluid-like and elastic features, leading to locomotor dynamics that are strongly influenced by the geometry of the surface, which, in itself, can be a dynamical entity. To gain insight into principles by which locomotors are influenced via a deformation field alone (and can influence other locomotors), we study robot locomotion on an elastic membrane, which we propose as a model of active systems on highly deformable interfaces. As our active agent, we use a differential driven wheeled robotic vehicle which drives straight on flat homogeneous surfaces, but reorients in response to environmental curvature. We monitor the curvature field–mediated dynamics of a single vehicle interacting with a fixed deformation as well as multiple vehicles interacting with each other via local deformations. Single vehicles display precessing orbits in centrally deformed environments, while multiple vehicles influence each other by local deformation fields. The active nature of the system facilitates a differential geometry–inspired mathematical mapping from the vehicle dynamics to those of test particles in a fictitious “spacetime,” allowing further understanding of the dynamics and how to control agent interactions to facilitate or avoid multivehicle membrane-induced cohesion.

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“…As a result, live larva aggregates do not jam like grains in a fluidization-defluidization cycle. Active granular fluids span from the scale of plant cells [31] to that of fly larvae and can be realized with centimeter-scale robots [32]. It remains an open question how these active fluids consisting of millimeter-scale or micrometer-scale constituents behave differently from traditional fluids made up of nanometer-scale molecules.…”

Section: Discussionmentioning

confidence: 99%

Air-Fluidized Aggregates of Black Soldier fly Larvae

Cassidy

Shishkov

et al. 2021

Front. Phys.

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Black soldier fly larvae are a sustainable protein source and play a vital role in the emerging food-waste recycling industry. One of the challenges of raising larvae in dense aggregations is their rise in temperature during feeding, which, if not mitigated, can become lethal to the larvae. We propose applying air-fluidization to circumvent such overheating. However, the behavior of such a system involves complex air-larva interactions and is poorly understood. In this combined experimental and numerical study, we show that the larval activity changes the behavior of the ensemble when compared to passive particles such as dead larvae. Over a cycle of increasing and then decreasing airflow, the states (pressure and height) of the live larva aggregates are single-value functions of the flow speed. In contrast, dead larva aggregates exhibit hysteresis characteristic of traditional fluidized beds, becoming more porous during the ramp down of airflow. This history-dependence for passive particles is supported by simulations that couple agent-based dynamics and computational fluid dynamics. We show that the hysteresis in height and pressure of the aggregates decreases as the activity of simulated larvae increases. To test if air fluidization can increase larval food intake, we performed feeding trials in a fluidization chamber and visualized the food consumption via x-ray imaging. Although the food mixes more rapidly in faster airflow, the consumption rate decreases. Our findings suggest that providing moderate airflow to larval aggregations may alleviate overheating of larval aggregations and evenly distribute the food without reducing feeding rates.

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Programming active cohesive granular matter with mechanically induced phase changes

Cited by 33 publications

References 56 publications

From collections of independent, mindless robots to flexible, mobile, and directional superstructures

From collections of independent, mindless robots to flexible, mobile, and directional superstructures

Field-mediated locomotor dynamics on highly deformable surfaces

Air-Fluidized Aggregates of Black Soldier fly Larvae

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