A Cooperative Decentralized PI Control Strategy: Discrete-time Analysis and Nonlinear Feedback*

This paper discusses an extension of a PI control strategy towards the control of a large m x m-MIMO system. This strategy is fully decentralized, it requires only the tuning of m different controllers, while we only allow for neighboring controllers to exchange error signals. This makes it a strong candidate for an implementation on a decentralized, low-power and high performance Wireless Sensor Network (WSN). The main idea is to feed locally observed control errors ('feedback') not only into the local control law, but also in a fixed proportionate way into neighboring controllers. The analysis concerns convergence to a set point. The analysis is essentially based on a conversion of the PI control law into a discrete-time gradient descent scheme. As an interesting byproduct, this analysis indicates how to deal with quantization functions and nonlinear effects in the feedback signals.