Two-level design for aperiodic networked control systems

Two critical issues in networked control systems are coupling of control and communication, and energy economy, especially for battery powered wireless sensor nodes. In this regard, a two-level design procedure for multiple loops with H_∞ based self-triggered control applied over the modified IEEE 802.15.4 wireless protocol is presented. Control and communication are decoupled by introducing an upper-bound on the transmission rate, and optimal usage of communication bandwidth and energy is guaranteed by modifying the wireless protocol. The presented priority-based scheduling algorithm can accommodate more systems as compared with the number of available transmission slots, while being efficient in terms of computational load and energy consumption. Simulation results show a significant reduction in energy expenditure in terms of decrease in duty cycle as compared with the periodic implementation.