Control of Multi-Agent Formations with Only Shape Constraints

TL;DR

This paper introduces a novel formation control approach for multi-agent systems that focuses on shape constraints without fixed scale, using nonlinear control laws to ensure exponential convergence and demonstrating improved performance with time-varying scales.

Contribution

It proposes a new shape-based formation control method that allows flexible scaling, extending from three agents to multiple agents, and applies it to sensor localization tasks.

Findings

Time-varying scale functions outperform fixed scales in formation convergence.

The control laws guarantee exponential convergence to the desired shape.

Application to bearing-only sensor-target localization demonstrates practical potential.

Abstract

This paper considers a novel problem of how to choose an appropriate geometry for a group of agents with only shape constraints but with a flexible scale. Instead of assigning the formation system with a specific geometry, here the only requirement on the desired geometry is a shape without any location, rotation and, most importantly, scale constraints. Optimal rigid transformation between two different geometries is discussed with especial focus on the scaling operation, and the cooperative performance of the system is evaluated by what we call the geometries degrees of similarity (DOS) with respect to the desired shape during the entire convergence process. The design of the scale when measuring the DOS is discussed from constant value and time-varying function perspectives respectively. Fixed structured nonlinear control laws that are functions on the scale are developed to guarantee the exponential convergence of the system to the assigned shape. Our research is originated from a three-agent formation system and is further extended to multiple (n > 3) agents by defining a triangular complement graph. Simulations demonstrate that formation system with the time-varying scale function outperforms the one with an arbitrary constant scale, and the relationship between underlying topology and the system performance is further discussed based on the simulation observations. Moveover, the control scheme is applied to bearing-only sensor-target localization to show its application potentials.