The stability of multi-robot flocking is closely related to the control model and the quality of wireless communications. In this study, we delve into the discrete-time flocking control problem for ...multi-robot systems (MRS) operating under an ad hoc network with random link failures. Specifically, we initially propose a discrete-time control model for multi-robot flocking that describes the inherent instability in the transmission of robot state information as a Bernoulli variable. Compared to existing controllers, this model requires less information exchange and is more practical for implementation in multi-robot systems. Subsequently, stability analysis is conducted for the controller, revealing that the MRS cannot achieve asymptotic flocking but can attain flocking in expectation when relevant stability conditions are satisfied. The stability conditions are deduced using the Lyapunov method, imposing constraints on the controller gains, the interaction period, and the successful transmission probability of communication links. Notably, the upper bound for the interaction period is significantly improved, thereby alleviating the communication network's burden. Simulation results verify the efficacy of the proposed control model and the reliability of the derived stability conditions.
The processing delay is incorporated into the influence function of the well-known Cucker–Smale model for self-organized systems with multiple agents. Both symmetric and non-symmetric pairwise ...influence functions are considered, and a Lyapunov functional approach is developed to establish the existence of flocking solutions for the proposed delayed Cucker–Smale model. An analytic formula is given to calculate the asymptotic flocking velocity in terms of model parameters and the variation of the position during the initial time interval.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Ratchet Effects in Active Matter Systems Reichhardt, C.J. Olson; Reichhardt, C
Annual review of condensed matter physics,
03/2017, Volume:
8, Issue:
1
Journal Article
Peer reviewed
Open access
Ratchet effects can arise for single or collectively interacting Brownian particles on an asymmetric substrate when a net dc transport is produced by an externally applied ac driving force or by ...periodically flashing the substrate. Recently, a new class of active ratchet systems that do not require the application of external driving has been realized through the use of active matter; they are self-propelled units that can be biological or nonbiological in nature. When active materials such as swimming bacteria interact with an asymmetric substrate, a net dc directed motion can arise even without external driving, opening a wealth of possibilities such as sorting, cargo transport, or micromachine construction. We review the current status of active matter ratchets for swimming bacteria, cells, active colloids, and swarming models, focusing on the role of particle-substrate interactions. We describe ratchet reversals produced by collective effects and the use of active ratchets to transport passive particles. We discuss future directions including deformable substrates or particles, the role of different swimming modes, varied particle-particle interactions, and nondissipative effects.
The authors interest in this work is to perform a precise real-time flocking of multiple unmanned aerial vehicles (UAVs). A consensus-based flocking algorithm that ensures a precise security distance ...between UAVs is proposed. By using Lyapunov theoretical analysis, the authors propose a flocking algorithm that ensures the ultimate boundedness of multiple-UAV system solutions. Moreover, this algorithm is enhanced by a distributed integral control that renders the inter-distances between UAVs more precise. Finally, experimental results are provided to prove and show the efficiency of these algorithms.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
We present a global existence theory for strong solution to the Cucker–Smale–Navier–Stokes system in a periodic domain, when initial data is sufficiently small. To model interactions between flocking ...particles and an incompressible viscous fluid, we couple the kinetic Cucker–Smale model and the incompressible Navier–Stokes system using a drag force mechanism that is responsible for the global flocking between particles and fluids. We also revisit the emergence of time-asymptotic flocking via new functionals measuring local variances of particles and fluid around their local averages and the distance between local averages velocities. We show that the particle and fluid velocities are asymptotically aligned to the common velocity, when the viscosity of the incompressible fluid is sufficiently large compared to the sup-norm of the particles' local mass density.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We deal with a sufficient framework for the finite-time flocking of an uncountable number of agents. To do this, we initially propose a continuum Cucker–Smale-type model, building upon the existing ...Cucker–Smale model designed for a finite number of agents within the continuum limit regime. Subsequently, we reduce this continuum model to a suitable dissipative structure; then we present admissible data in terms of the initial data and system parameters that allow finite-time flocking to occur.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We analyze the Cucker–Smale model under hierarchical leadership in presence of a time delay. By using a Lyapunov functional approach and some induction arguments we will prove convergence to ...consensus for every positive delay τ. We also prove a flocking estimate in the case of a free-will leader. These results seem to point out the advantage of a hierarchical structure in order to contrast time delay effects that frequently appear in real situations.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this article, we investigate leader-follower flocking for the Cucker-Smale model with lossy links and general weight functions. Here, the loss phenomenon of the control packages from the ...controller to the actuator is characterized by a Bernoulli stochastic variable and the edge weights of the interaction network are determined by a general update rule based on the distance between agents. A method based on the products of substochastic matrices is developed to analyze the flocking behavior with lossy links. By means of this method, a sufficient condition which depends on the agents' initial states, the topology structure, the successful information transmission rate and the weight function is established. Compared with the previous Cucker-Smale flocking results, which are only applicable to positive and decreasing weight functions with specific forms, our result is more general and can be applied to arbitrary positive and decreasing weight functions with nonzero lower bounds. Finally, our result is illustrated through a simulation example.
In this article, we present a new Cucker-Smale model on smooth Riemannian manifolds using the concepts of covariant derivative and parallel transport, and we also study its emergent dynamics under an ...a priori assumption on the energy functional. For Euclidean space, our proposed model coincides with the original Cucker-Smale model. As concrete examples, we consider three Riemannian manifolds: the unit 2-sphere, the unit circle, and the Poincaré half-plane, and provide explicit reductions from the proposed general model to aforementioned manifolds via explicit formulas for the covariant derivative and parallel transport.
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