arXiv subjects

Rodrigo Saavedra

Publications and source records attributed to Rodrigo Saavedra.

4 recordsLinked to original sources

arXiv2024

Directed Swarm Assembly due to Mixed Misaligned Perception-Dependent Motility

A mixture of particles with perception-dependent motility and opposite misaligned visual perception shows to spontaneously self-organize into a self-propelling bean-shaped cluster. The two species initially rotate in opposite directions, which together with the steric interactions, makes them segregate into two main counter-rotating domains forming a cohesive and persistently propelling single cluster. Mixtures of particles with misaligned perception and discontinuous motility are therefore a promising pathway for the design of programmable active matter.

cond-mat.soft↗

arXiv2024

A Surveillance Game between a Differential Drive Robot and an Omnidirectional Agent: The Case of a Faster Evader

A fundamental task in mobile robotics is to keep an agent under surveillance using an autonomous robotic platform equipped with a sensing device. Using differential game theory, we study a particular setup of the previous problem. A Differential Drive Robot (DDR) equipped with a bounded range sensor wants to keep surveillance of an Omnidirectional Agent (OA). The goal of the DDR is to maintain the OA inside its detection region for as much time as possible, while the OA, having the opposite goal, wants to leave the regions as soon as possible. We formulate the problem as a zero-sum differential game, and we compute the time-optimal motion strategies of the players to achieve their goals. We focus on the case where the OA is faster than the DDR. Given the OA's speed advantage, a winning strategy for the OA is always moving radially outwards to the DDR's position. However, this work shows that even though the previous strategy could be optimal in some cases, more complex motion strategies emerge based on the players' speed ratio. In particular, we exhibit that four classes of singular surfaces may appear in this game: Dispersal, Transition, Universal, and Focal surfaces. Each one of those surfaces implies a particular motion strategy for the players.

cs.RO↗

arXiv2024

Self-trapping of active particles with non-reciprocal interactions in disordered media

We study systems of active particles, whose perception is constrained by a vision cone, that are attracted to other particles and repelled from static obstacles. We report a novel self-trapping mechanism: active particles with non-reciprocal attraction form particle chains, which eventually become closed loops that shrink around one or many obstacles. These closed loops act as effective aggregation centers. Long-lived, self-organized closed loops require to enclose obstacles to exist. Furthermore, we find that closed loops that initially exhibit local polar order, transition to a nematic state as they absorb more particles. The unveiled mechanism corresponds to a pinning behavior that strongly hinders particle diffusion. In short, closed loops dominate the large-scale properties of active systems with non-reciprocal attraction in disordered media.

cond-mat.stat-mech↗

arXiv2024

Swirling due to misaligned perception-dependent motility

A system of particles with motility variable in terms of a vision-type of perception is here investigated by a combination of Langevin dynamics simulations in two-dimensional systems and an analytical approach based on conservation law principles. Persistent swirling with predetermined direction is here induced by differentiating the self-propulsion direction and the perception cone axis. Clusters can have a fluid-like center with a rotating outer layer, or display a solid-like rotation driven by the outer layer activity. Discontinuous motility with misaligned perception might therefore serve as a powerful self-organization strategy in micro-robots.

cond-mat.soft↗