Co-design Of Networked Control Systems With Bandwidth Constraint And Communication Energy Limitation

With the advent of networked control systems (NCSs), multiple subsystems can achieve information sharing and coordination via wireless network. However, due to the bandwidth constraint, at each time only some subsystems can have access to the network. When a plant gains access to the network, packet dropout may happen due to the noises in the wireless channel. Increasing the transmission power of nodes can reduce the packet dropout rate. However, it will increase the system's communication energy consumption and reduce the service life of the nodes. Therefore, in order to ensure that all subsystems are simultaneously stable, the procedure of controller design implies establishing a communication scheduling policy and a power allocation scheme at the same time.This paper investigates the combined issues of bandwidth constraint, packt dropout and communication energy limitation in linear time-invariant NCSs. The object is to find a co-design algorithm of channel accessing policy, feedback controller and power allocation policy such that the control performance of system can be guaranteed with respect to the communication energy limitation. The main contents are given as below.1. The effects of random channel accessing sequences on the stability of NCSs with bandwidth constraint are taken into account from the sensor-to-controller side and controller-to-actuator side, respectively. By using the Lyapunov method and stochastic system theory, the relations among the packet successful transmission probability, the channel transform probability and the system stability are established. Then based on the obtained results, sequence-dependent and sequence-independent controllers are designed. In order to verify the effectiveness of the above method, the vehicle platoon control system is given as an application example. With the design of sequence-independent controller, the stability and H? performance of vehicle platoon can be guaranteed.2. The stability of NCSs with communication energy limitation is taken into account. By modeling the wireless channel, the relations between transmission power and packet dropout rate are established. Then based on the new channel model, two co-design algorithms of transmission power allocation and controller are proposed in the case of the static and random power allocation strategies respectively. The simulation results show that the above two algorithms can both stabilize the systems with desire control performance and satisfy the communication energy limitation.3. The effects of static and random channel accessing sequences on the stability of NCSs with bandwidth constraint and communication energy limitation are taken into account. Firstly, for the NCSs with static channel accessing sequence, a co-design algorithm of channel accessing sequence, controller design and transmission power allocation policy is proposed by using switching system theory and convex optimization method. Secondly, for the NCSs with random channel accessing sequence, a co-design algorithm of channel accessing probability, controller design and transmission power allocation policy is proposed by using stochastic system theory and Lyapunov method. The theoretical research shows that the above two algorithms can stabilize the systems with desire decay rates and complying with given energy budget.