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A new method for the design of network-based control systems, together with mathematical tools for closedloop stability assessment, is proposed. In order to preserve the closed-loop stability under random network time delays, the variable selective control (VSC) methodology is introduced, which combines the idea of variable sampling control with the packetbased control methodologies. In the proposed method, eventdriven sensors are employed, which sample the plant output just after a new control input signal is received by the actuator. The advantages are as follows: 1) the latest actual sampling period becomes equal to the most recent time delay, which is known by direct measurement; 2) better estimation of the actual plant states can be performed in the predictive controller; 3) less frequent and shorter packets need to be transferred through the network; and 4) the stability analysis becomes simpler and does not depend on variable-size matrices. In order to deal with packet dropout issue, a simple, yet effective, algorithm is adopted in the controller, where packet losses are considered as variable time delays. In light of this formulation, the networked control system can be considered as a switched linear system and, therefore, previously existing theoretical results are adopted for stability analysis of the VSC method. Simulation studies on a well-known benchmark problem demonstrate the effectiveness of the proposed method.Index Terms-Network-based control system, networked control system, packet-based control, variable sampling period, variable selective control (VSC).

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