## Abstract

In this paper, we investigate the exact controllability properties of an advection-diffusion equation on a bounded domain, using time- and space-dependent velocity fields as the control parameters. This partial differential equation (PDE) is the Kolmogorov forward equation for a reflected diffusion process that models the spatiotemporal evolution of a swarm of agents. We prove that if a target probability density has bounded first-order weak derivatives and is uniformly bounded from below by a positive constant, then it can be reached in finite time using control inputs that are bounded in space and time. We then extend this controllability result to a class of advection-diffusion-reaction PDEs that corresponds to a hybrid-switching diffusion process (HSDP), in which case the reaction parameters are additionally incorporated as the control inputs. Our proof for controllability of the advection-diffusion equation is constructive and is based on linear operator semigroup theoretic arguments and spectral properties of the multiplicatively perturbed Neumann Laplacian (a(x)). For the HSDP, we first constructively prove controllability of the associated continuous-time Markov chain (CTMC) system, in which the state space is finite. Then we show that our controllability results for the advection-diffusion equation and the CTMC can be combined to establish controllability of the forward equation of the HSDP. Lastly, we provide constructive solutions to the problem of asymptotically stabilizing an HSDP to a target non-negative stationary distribution using timeindependent state feedback laws, which correspond to spatiallydependent coefficients of the associated system of PDEs.

Original language | English (US) |
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Journal | IEEE Transactions on Automatic Control |

DOIs | |

State | Accepted/In press - Jan 1 2018 |

## Keywords

- advection-diffusion-reaction PDE
- continuous-time Markov chains
- controllability
- stochastic processes
- Swarm robotics

## ASJC Scopus subject areas

- Control and Systems Engineering
- Computer Science Applications
- Electrical and Electronic Engineering