Networked Control for Nonlinear Plants Subject to Updating Disorder

This paper addresses a networked control problem for nonlinear plants that are subject to several network-induced issues simultaneously, including multiple independent communication channels, time-varying transmission intervals, sensor schedule protocols, large transmission delays, and updating disorder. A new indicator, the maximum number in updating disorder, is proposed to evaluate the intensity of updating disorder. Then, to describe the complicated relationship between transmission and updating time sequences in the presence of updating disorder, some auxiliary variables are introduced which result in two new memory vectors for computing the update of measurement errors. Subsequently, after an elaborate investigation for the evolutions of the introduced variables and vectors, a new hybrid model is established for the closed-loop system. Furthermore, sufficient conditions on closed-loop stability are proposed by constructing a new function that characterizes the effects of the evolutions of measurement errors in different cases of transmission and updating. Moreover, a popular mechanism in existing studies for compensating updating disorder is reviewed. Its efficiency is evaluated after comparing the stability conditions with and without using compensation mechanisms. Finally, a practical nonlinear example of single-link robot arms is simulated to illustrate the feasibility and efficiency of the theoretical results.