Giacomo Casadei

Robust output synchronization of a network of heterogeneous nonlinear agents via nonlinear regulation theory

In this paper, we consider the output synchronization problem for a network of heterogeneous diffusively-coupled nonlinear agents. Specifically, we show how the (non-identical) agents can be controlled in such a way that their outputs asymptotically track the output of a prescribed nonlinear exosystem. The problem is solved in two steps. In the first step, the problem of achieving consensus among (identical) nonlinear reference generators is addressed. In this respect, it is shown how the techniques recently developed to solve the consensus problem among linear agents can be extended to agents modeled by nonlinear d-dimensional differential equations, under the assumption that the communication graph is connected. In the second step, the theory of nonlinear output regulation is applied in a decentralized control mode, to force the output of each agent of the network to robustly track the (synchronized) output of a local reference model.

An open-source architecture for control and coordination of a swarm of micro-quadrotors

This work presents the design of an open-source control architecture specifically tailored to the rapid development and testing of control and coordination algorithms on micro quadrotors. The proposed design extends an existing open-source and open-hardware quadrotor project, i.e., the Crazyflie nano quadrotor, by adding the guidance, navigation and control layers required to accomplish autonomous flight. The control layer, in particular, is based on a cascade control algorithm able to globally stabilize the position and the attitude of the vehicle. The global property guaranteed by the algorithm allows the quadrotors to perform aggressive maneuvers. The guidance layer is designed to coordinate simultaneously multiple vehicles by generating suitable reference trajectories. Experiments demonstrate the effectiveness of the proposed design.

About synchronization of homogeneous nonlinear agents over switching networks

In this paper, we consider the problem of achieving consensus in a homogeneous network of nonlinear agents. The network topology switches within a finite set of connected topologies that persist on a certain interval of time possibly of zero length. Under this condition we prove that, if the rule underlying the switching of the topologies fulfills an average dwell-time, then consensus is achieved. The idea that is pursued in the paper to prove the result is to study the networked system as an hybrid inclusion and to adopt Lyapunov arguments proposed in the literature about hybrid nonlinear systems.

Synchronization of nonlinear oscillators over networks with dynamic links

In this paper we investigate the problem of synchronization of homogeneous nonlinear oscillators coupled by dynamic links. The output of the nonlinear oscillators is the input to the dynamic links, while the output of these dynamic links is the quantity available to the distributed controllers at the nodes to impose synchronization of the network. In particular, inspired by the practical case of nonlinear oscillators connected over an electrical network, we extend a theoretical framework proposed to deal with the synchronization of nonlinear oscillators to the case of networks with dynamic links and guarantee that synchronization is achieved.

Internal model-based control for loitering maneuvers of UAVs

In this paper we present a modular control architecture for unmanned aerial vehicles. Given a stabilizing control law, we aim to improve the performances of the vehicle by means of an internal model regulator. To simplify the design procedure, which especially in the nonlinear case might be fairly complicated, we show how it is possible to compose the separate control modules (stabilization and internal model) in an easy and reliable structure. The proposed technique will be tested on the loitering benchmark: in other words, the UAV is required to follow a target and perform a dynamic trajectory around it.

Quadrotors motion coordination using consensus principle

In this paper we investigate the problem of motion coordination of a class of multi-agent robotic systems. By means of consensus theory, we implement a decentralized control scheme which relies on the exchange of information between agents in order to obtain a coordinated motion trajectory. The key feature of this approach relies in the fact that consensus is applied to a set of exosystems (one for each agent), which can be thought of as local reference generators. By tracking the generated coordinated reference the desired formation and trajectory is achieved.

Space vector-based modeling and control of a modular multilevel converter in HVDC applications

Modular multilevel converter (MMC) is an emerging multilevel topology for high-voltage applications that has been developed in recent years. In this paper, the modeling and the control of MMCs are restated in terms of space vectors, which may allow a deeper understanding of the converter behavior. As a result, a control scheme for three-phase MMCs based on the previous theoretical analysis is presented. Numerical simulations are used to test its feasibility.