Repetitive tracking position control on LonWorks/IP network with time varying delay

LonWorks over IP (LonWorks/IP) network is an integrated form of LonWorks device network and IP data network. Lon Works/IP network can offer ubiquitous access to the information on the factory floor and the real-time distributed control can be made possible. Timely response is inevitable for the real-time distributed control on the factory floor. Network induced uncertain time delay deteriorates the performance and stability of the real-time distributed control system on Lon Works/IP network. Therefore, time-varying uncertain time delay needs to be compensated for, in order to guarantee the stability and to improve the performance of the networked distributed control system. In this paper a control scheme based on disturbance observer and repetitive controller for the real-time distributed control on LonWorks/IP network with time-varying delay is proposed and tested through experiment. The result of the proposed control is compared with that of internal model controller (IMC) based on Smith predictor and disturbance observer. It is shown that the proposed control scheme can improve the tracking performance of the periodic reference.