Collaborative control of wave glider platforms - Local Communication and Sea State Estimation

• Main Author: Fangbemi, Kossivi Agbessi
• Other Authors: Boje, Edward, Verrinder, Robyn A
• Format: Master Thesis
• Language: English
• Published: Faculty of Engineering and the Built Environment 2019
• Subjects: Wave Glider Platform; Unmanned Marine Vehicle; Low Power Wireless Communication; Probability; Southern Ocean
• Online Access: http://hdl.handle.net/11427/31411; https://open.uct.ac.za/bitstream/11427/31411/4/thesis_ebe_2019_fangbemi_kossivi_agbessi.pdf

Climate change is the focus of many oceanography and marine engineering researchers, with possible links between climate change and the carbon cycle in the Southern Ocean being considered. This type of investigation requires modern and cost-effective tools to conduct surveys and collect data from the ocean. The self-propelled unmanned surface vessel, the Liquid Robotics Wave Glider, was designed primarily as a marine research tool and offers several advantages over existing research vessels and other tools employed for data acquisition in the ocean. The main advantages are its robustness at sea, i.e. its ability to withstand extreme weather conditions, its propulsion energy source, which is the wave energy, and its customisable electronics payload. The inter-platform communication strategy of the Wave Glider inspired a few engineering questions, one of which is the focal point of this research: whether Low Power Wide Area Network (LPWAN) technology can be used to set up a local communication system enabling the collaboration of two or more Wave Gliders and reduce the cost, in terms of power and communication channels, involved in the communication with the Wave Glider platforms during missions. This research considers various LPWAN technologies available on the market and proposes LoRaWAN technology for the local communication system. LoRaWAN was selected as it presented a robust radio modulation and had growing support in the industry. In this research, a LoRa-based network of two nodes was developed, implemented and tested over the surface of the ocean. It was found that the system performs well over a distance of 1 km with both antennas having one end at the mean surface level of the sea. With the intention to increase the range of the platform and achieve a reliable and robust system, the research continued with the study of the influence of the surface waves on the proposed local communication system by exploring, firstly, the impact of seawater and, secondly, the wave height on signal transmission. The ...