Robustness of networked control systems with multiple actuator-links and bounded packet dropouts

This paper presents an MPC based controller and network protocol co-design strategy for networked control systems with multiple controller-actuator links. These links are closed via unreliable data-like network which allows access to only one actuator node at each time instant. The concept of nonlinear gains is used to show that in the case of uniform boundedness of the number of consecutive packet dropouts, nonlinear gain ℓ2 stability can be ensured via appropriate choice of design parameters. Numerical simulations illustrate the potential of the proposed strategy.</p

Packetized MPC with dynamic scheduling constraints and bounded packet dropouts

We study a Networked Control System architecture which uses a communication network in the controller-actuator links. The network is affected by packet dropouts and allows access to only one plant input node at each time instant. This limits control performance significantly. To mitigate these limitations we propose a control and network protocol co-design method. Succinctly, the underlying features of the proposed method are as follows: a sequence of predicted optimal control values over a finite horizon, for an optimally chosen input node, is obtained using Model Predictive Control ideas; the <i>entire</i> resulting sequence is sent to the chosen input node; a smart actuator is used to store the predictions received and apply them accordingly. We show that if the number of consecutive packet dropouts is uniformly bounded, then partial nonlinear gain ℓ₂ stability and also a more traditional linear gain ℓ₂ stability can be ensured via appropriate choice of design parameters and the right assumptions. Whilst our results apply to general nonlinear discrete-time multiple input plants affected by exogenous disturbances, for a disturbance-free case we prove that Global Asymptotic Stability follows from our main result. Moreover, we show that by imposing stronger assumptions, Input-to-State Stability is achievable as well. Finally we demonstrate the potential of the proposed method via simulations

Robust stability of a class of Networked Control Systems

Networked Control Systems (NCSs) affected with packet dropouts and scheduling are considered. The undesirable effects of packet dropouts and scheduling, such as instability or deteriorated performance, are addressed by application of a protocol and controller co-design method. The used method exploits Model Predictive Control (MPC) framework and the flexible NCS architecture which allows for distributed computation. Uniform Global Asymptotic Stability (UGAS) is established by assuming a finite bound on the number of consecutive packet dropouts and appropriate modifications to often adopted MPC stability-related assumptions. Two approaches that demonstrate UGAS are provided. The proof of one approach consists of finding an appropriate Lyapunov candidate function, while the other uses a cascade stability idea