Modeling And Control Of A Zigbee Based Wireless Networked Control System

Networked Control systems (NCSs) have been attracted many attentions as a new develop-ment stage of the control theory. They are a combination of computer technology, communication technique and control theory, standing for the developing tendency of the control systems to the the networked, integrated and intellectual systems. NCSs have many advantages, such as low cost, easy installation and maintenance, information sharing, flexibility. They have been applied in many area, i.e. industrial automation, aerospace field, smart home, intelligent transportation system et al. Meanwhile, as the extension and complement of the wired networks, wireless based networked control systems also have a wide applications. However, as the introduction of the networks to the control systems, many challenging problems arise, such as, network induced delay, data loss, packet disordering and so on. And the traditional control theory can’t be applied to the NCSs, they must be reevaluated before applying to the NCSs.We study the problems of modeling and control of a Zigbee based wireless networked control systems.Firstly, we establish a wireless networked control system platform to test the communication properties of the wireless network and propose the Poisson distribution models to describe the network induced delay under the topology of one hop or multi hops. The effectiveness of the proposed models are verified by an estimation experiment.Secondly, we consider the case when data delay and data loss exist simultaneously in the wireless network. The wireless networked control system is modeled to be a switched system with time varying delays. And the stabilization and H∞control problems are solved based on the obtained model. Numerical examples illustrate the effectiveness of the proposed methods.Finally, the stabilization problem of the wireless networked control system when the con-trolled plant is unstable is considered. A switched system model is developed via augmented the system states. A controller design approach is obtained by the asynchronous dynamic system the-ory. Numerical examples illustrate the effectiveness of the proposed approach.