TY - THES

T1 - Networked Control Systems With Communication Delays

AU - Mattathil, Gemith

N1 - no embargo

PY - 2023

Y1 - 2023

N2 - On the internet, it can come to connection delays due to different reasons, like network congestion, distance between communicating devices and bandwidth limitations. This can lead to many inconveniences and difficulties for users communicating through the Internet. For digital control systems, it becomes challenging to manage and regulate processes in plants adequately with controllers that are connected over the internet. This thesis focuses on finding a fitting closed-loop digital controller to manage and regulate a processing plant on the internet despite the normally present delays, by first observing and evaluating internet delays by measuring these from different locations. The time measurements of the delays were measured over different distances, including cross-continental connections, and attempted to be during similar time periods through an MQTT broker. These measurements were evaluated using histograms to observe the existing delays and find correlations between the delays and the measurement parameters. An experiment including a PI controller, programmed in MATLAB had been assembled to control a second-degree plant in the form of a resistance-capacitor-loop. The communication between the controller and plant is established through the internet, which causes delays in this information exchange. Additionally there is a conversion of the communication protocols of the internet UDP and TCP during the information exchange. The missing components of the state vector were estimated with a Luenberger Observer and used in the PI controller. The error value was calculated from the return signal of the plant. It provided an indication of whether the system was operating as intended.

AB - On the internet, it can come to connection delays due to different reasons, like network congestion, distance between communicating devices and bandwidth limitations. This can lead to many inconveniences and difficulties for users communicating through the Internet. For digital control systems, it becomes challenging to manage and regulate processes in plants adequately with controllers that are connected over the internet. This thesis focuses on finding a fitting closed-loop digital controller to manage and regulate a processing plant on the internet despite the normally present delays, by first observing and evaluating internet delays by measuring these from different locations. The time measurements of the delays were measured over different distances, including cross-continental connections, and attempted to be during similar time periods through an MQTT broker. These measurements were evaluated using histograms to observe the existing delays and find correlations between the delays and the measurement parameters. An experiment including a PI controller, programmed in MATLAB had been assembled to control a second-degree plant in the form of a resistance-capacitor-loop. The communication between the controller and plant is established through the internet, which causes delays in this information exchange. Additionally there is a conversion of the communication protocols of the internet UDP and TCP during the information exchange. The missing components of the state vector were estimated with a Luenberger Observer and used in the PI controller. The error value was calculated from the return signal of the plant. It provided an indication of whether the system was operating as intended.

KW - Networked Control System

KW - Internet of Things

KW - Communication delay in System

KW - Vernetzte Regelsysteme

KW - Internet der Dinge

KW - kommunikationsbedingte totzeitsystem

U2 - 10.34901/mul.pub.2023.145

DO - 10.34901/mul.pub.2023.145

M3 - Master's Thesis

ER -