Design a PID controller with missing packets in a networked servo-system

Abstract

Networked Control Systems (NCS) are defined as the systems in which a feedback control loop is implemented through a network. The networks employed for this task are based on a range of protocols. The data communicated through the network often face network congestions or collisions resulting in the loss of data carrying packets. This can impose a serious problem for the stability of the networked control systems. In this project, one such problem is studied, “Design of a PID controller with missing packets in a networked servo-system”. The controller under consideration is a discrete PID controller and the packets carrying error signals in a succession are considered missing. The plant is a part of an analogue servo-system. Thus, to use an analogue plant in a digital environment a digitization process is included and a networked model of the system is proposed. In the networked model of the servo-system, Ethernet is proposed as a network, so construction of Ethernet packet and reasons for its loss are given. In Simulations, the discrete PID controller and system showed undesirable characteristics, so the controller is tuned using Steepest Descent Gradient Method. To aid the quick functioning of the method, a program in C has been developed. The optimized responses with missing error packets are compared and analyzed.