Different scheduling techniques using robust control for network control systems

Abstract

The idea of this Research is to reduce network induced time delay in network controlled system (NCS) and to determine the best network. Main matters in NCS are robust, nonlinear processes and time-varying. Camera based traceability system is considered as NCS with sensors and actuators designed for storing data for traceability. In this research work camera-based barcode traceability is taken as a model for network control system. The main challenge in this system is network induced delay, which is reduced by scheduling technique and by selecting suitable network for PID control with modified Earliest Deadline First (EDF) scheduling is determined among CAN, Ethernet, Switched Ethernet, TDMA and FDMA. EDF scheduling algorithm is modified and used for the control change with the operating conditions depending on the requirements to control the camera bar code traceability system simulated using PID. CAN and Ethernet have the minimum of 1ms network induced time delay when compared with Switched Ethernet, TDMA and FDMA under overload condition. The proposed IMC based EDF Scheduled controller utilization is estimated as U = 0.12 and the integral of absolute error (IAE) value of the proposed IMC based EDF Scheduled controller is 0.00354 is employed to measure the quality of control (QoC) of each control loop value. PID controller is developed by combining both gain scheduling and IMC method to reduce the time delay effort in camera bar code traceability system. The main idea in our research is robust PID controller, whenever there is a change in the data traffic in the network, the PID controller will switch its parameters from one set to another one to recompense for the change in the time delays in the system. The derivation and simulation of the proposed controller structure and the controller switching parameters under different traffic conditions assessed when the NCS has time-varying delays. The control performance of the PID controllers designed for fixed time delay and that for random time delays are compared