Discussion on: ''Integral Sliding Mode Control for a Class of Uncertain Switched Nonlinear Systems''

The paper by Liana, Zhao, and Dimirovskid shows one of the latest advances in switched systems by incorporating sliding mode control with a nonlinear integral switching surface. It is worthwhile comparing two types of switching mechanisms employed in this work. The first type is the system structural switching with an average dwell time. Hence, the switching frequency should be finite, and the stable structures should dominate the system response. The second type is the controller structural switching around a pre-specified switching surface. In theory, the switching frequency of the SMC should be infinite so that the sliding motion can be guaranteed. On the other hand, the SMC can switch among unstable structures to yield a stable sliding mode. In the paper, only the stabilization problem is addressed. The extension to tracking problems is a non-trivial issue. Finally, it would be helpful to provide illustrative examples that have both stable and unstable structures, as this point is the focus of the paper.