The impact of control delay upon the performance of a DC-motor control: Comparison of a centralized vs. a network-based approach

An important aspect when dealing with computer control systems is the impact of control delay upon the performance of the controlled item. Such control delay may be a consequence of the computer controlled implementation or, for the case of a network based control system, can be the consequence of the use of a communication network to interconnect sensors and actuators with the controller. Basically, control applications require a predictable delay between measurement and actuation, with small variability, i.e., small jitter. In this paper we present some simulation results concerning the impact of a varying control delay upon the performance of a DC-motor, both for a centralized computer-controlled setup and for a network based control system. The results for the centralized setup were also experimentally confirmed. For the network-based setup it was used the h-BEB real-time communication protocol. The evaluated scenarios were simulated using the TrueTime simulator that is based in MATLAB/Simulink. The experimental tests were developed in LabVIEW, where the controller task was executed as a software routine. The tests consisted in the variation of the sampling period and control delay to determinate the steady region of the system.