Implementation of a self-triggered control strategy over IEEE 802.15.4

• Main Author: Pantzar, Dan
• Format: Others
• Language: English
• Published: KTH, Reglerteknik 2011
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-57709

A self-triggered control strategy implementation on a IEEE 802.15.4 based network can prove to be quite difficult. In this master thesis project a study of the IEEE 802.15.4 protocol is conducted to understand what constraints it poses to an  iplementation of a self-triggered controller and the possibility to use it as a feedback link in a control process. A self-triggered control strategy recently introduced by Tiberi et al. is implemented on a wireless sensor network. An experimental test to prove that it is possible to use a self-trigger control is presented. A PI-controller is designed and used on a system where the temperature is measured with a wireless sensor located on a Mote(iv) Tmote Sky. The feedback link in the control process is over a IEEE 802.15.4 network. It is shown that a self-triggered control strategy delivers an equal control result compared to a periodic control strategy while reducing the energy consumption of the network. The results from the conducted experiments show that the hardware in use is not yet ready for the self-triggered control strategy. Even though the same control performance as a periodic controller was achieved, the hardware has some flaws. Problems with beacon adaptivity as well as computation constraints were discovered. It is concluded that for a system with low demands on precision and with a slow dynamic the self-triggered control performs well on Mote(iv) Tmote Sky units. However, a fast system with a high demand on precision is not ready for the self-triggered control implementation while using Tmote Sky platforms.