Distributed Consensus for Multiple Lagrangian Systems with Parametric Uncertainties and External Disturbances Under Directed Graphs

TL;DR

This paper develops distributed consensus algorithms for multiple Lagrangian systems with uncertainties and disturbances under directed graphs, ensuring leaderless consensus through adaptive, robust, and model reference strategies, even with switching topologies.

Contribution

It introduces novel adaptive and robust control algorithms for leaderless consensus in uncertain Lagrangian systems under directed graphs, including switching topologies and without velocity measurements.

Findings

Achieves weighted average consensus depending on topology and initial conditions.

Proposes algorithms that do not require velocity measurements of neighbors.

Validates effectiveness through numerical simulations.

Abstract

In this paper, we study the leaderless consensus problem for multiple Lagrangian systems in the presence of parametric uncertainties and external disturbances under directed graphs. For achieving asymptotic behavior, a robust continuous term with adaptive varying gains is added to alleviate the effects of the external disturbances with unknown bounds. In the case of a fixed directed graph, by introducing an integrate term in the auxiliary variable design, the final consensus equilibrium can be explicitly derived. We show that the agents achieve weighted average consensus, where the final equilibrium is dependent on three factors, namely, the interactive topology, the initial positions of the agents, and the control gains of the proposed control algorithm. In the case of switching directed graphs, a model reference adaptive consensus based algorithm is proposed such that the agents achieve leaderless consensus if the infinite sequence of switching graphs is uniformly jointly connected. Motivated by the fact that the relative velocity information is difficult to obtain accurately, we further propose a leaderless consensus algorithm with gain adaptation for multiple Lagrangian systems without using neighbors' velocity information. We also propose a model reference adaptive consensus based algorithm without using neighbors' velocity information for switching directed graphs. The proposed algorithms are distributed in the sense of using local information from its neighbors and using no comment control gains. Numerical simulations are performed to show the effectiveness of the proposed algorithms.