Leader-Follower Formation Tracking Control of Mobile Robots: A Visual Observer-Based Approach

Abstract

This brief addresses the leader-follower formation tracking control problem of nonholonomic mobile robots. The topology of the sensor network is described by a directed spanning tree. Notably, the position-denied case, where the positions of the mobile robots in the global reference frame are unknown, is considered. The unavailability of the positions of the mobile robots makes the formation tracking error not directly accessible. A visual observer is developed to estimate the relative formation tracking error. This observer is designed based on the feedback from odometry, a monocular camera, and an attitude and heading reference system (AHRS). Then, a dynamic visual controller, consisting of the observer and a velocity controller, is proposed. It is proved that the equilibrium of the augmented closed-loop multirobot system is asymptotically stable for any initial states of the robots. Finally, an experiment conducted on multiple mobile-wheeled robots illustrates the effectiveness.