Comments on ‘Distributed observers design for leader-following control of multi-agent networks,  Automatica, 44: 846–850, 2008’

In this note it is pointed out that the proof of Theorem 1 of Hong, Chen and Bushnell (2008) is incorrect for the theorem as stated. A proof for a modified version of the theorem is also given11While the paper was under review, we became aware that another way to address the error in Hong, Chen and Bushnell (2008) is to simply replace 1∕k with 1∕k2 in equation (4) of that paper, as was done in Wang and Hong (2009). With such change the proof of Hong, Chen and Bushnell (2008) is valid. We now also understand that the simulations in Hong, Chen and Bushnell (2008) were carried with the corrected 1∕k2 in equation (4) of Hong, Chen and Bushnell (2008)..