# Observer-Based Distributed Leader-Follower Tracking Control: A New Perspective and Results

## TL;DR

This paper introduces a novel observer-based framework for leader-follower tracking in multi-agent systems, enabling followers to estimate leader inputs locally, improving tracking performance especially when velocities are unmeasured.

## Contribution

It proposes a new input-observer-based approach for distributed leader-follower tracking, extending to second-order cases and unmeasured velocities, with rigorous convergence analysis.

## Key findings

- Effective input estimation improves tracking accuracy.
- Framework applicable to first- and second-order systems.
- Simulation confirms robustness and advantages over existing methods.

## Abstract

Leader-follower tracking control design has received significant attention in recent years due to its important and wide applications. Considering a multi-agent system composed of a leader and multiple followers, this paper proposes and investigates a new perspective into this problem: can we enable a follower to estimate the leader's driving input and leverage this idea to develop new observer-based tracking control approaches? With this motivation, we develop an input-observer-based leader-follower tracking control framework, which features distributed input observers that allow a follower to locally estimate the leader's input toward enhancing tracking control. This work first studies the first-order tracking problem. It then extends to the more sophisticated case of second-order tracking and considers a challenging situation when the leader's and followers' velocities are not measured. The proposed approaches exhibit interesting and useful advantages as revealed by a comparison with the literature. Convergence properties of the proposed approaches are rigorously analyzed. Simulation results further illustrate the efficacy of the proposed perspective, framework and approaches.