Model based networked control for time-varying delay and modeling error

Abstract

This paper proposes a compensation scheme for both the time varying delay and the plant model uncertainty. As well known, time delay in feedback loop does not only weaken system performance, in worst-case situations it can cause system unstable. Conventional research treated the time varying delay as uncertain perturbation; however it restricts the performance of the system. In fact, the time delay on a network is not completely uncertain. That is, it is measurable value. Therefore we propose a method to measure individual time delays and utilize them for the model-based compensator. In the model based control, the modeling error between the plant model and real plant can affect the performance and stability of the system. However, perfect modeling of the plant is very difficult; therefore we employed a robust control based compensator to avoid the instability due to uncertainty. To evaluate the performance of the proposed system, we carried out experiments on a motor control system. From the results, we verified the stability and satisfactory performance of the system with the proposed methods.