Observer design via Immersion and Invariance for vision-based leader–follower formation control

The paper introduces a new vision-based range estimator for leader–follower formation control, based upon the Immersion and Invariance (I&I) methodology. The proposed reduced-order nonlinear observer is simple to implement, easy to tune and achieves global asymptotical convergence of the observation error to zero. Observability conditions for the leader–follower system are analytically derived by studying the singularity of the Extended Output Jacobian. The stability of the closed-loop system arising from the combination of the range estimator and an input-state feedback controller is proved by means of Lyapunov arguments. Simulation experiments illustrate the theory and show the effectiveness of the proposed designs.