Comments on “Output synchronization of nonlinear heterogeneous multi-agent systems with switching networks”: [Systems & Control Letters 125 (2019) 45-50]

Abstract In this note, an effort is put forward to make two revisions with respect to mistakes in the derivations of Khan et al. (2019). The main result of Khan et al. (2019) claimed that the Laplacian matrix L is a symmetric matrix. However, the paper only assumed that the jointly connected graph contains a spanning tree. Clearly, L is a symmetric matrix if and only if the joint graph is strongly connected. Hence, the basic Assumption needs to be revised. Also, some equations need to be modified without treating L as a symmetric matrix. This revision will affect the stability conditions of switching topologies, which leading thereby to redesign the parameters λ and μ appeared in Theorem 4.1 (Khan et al., 2019). In addition, there is a mistake when the authors designing real reference systems. The output matrix C = [ C v , 0 ] should be C = [ N C v , 0 ] , otherwise the follower systems will track a wrong trajectory pattern.