Design and Development of a Data Acquisition and Communication System for Point Absorber Tracking

Sammanfattning: The recent trend in generating energy from the waves has led to several advancements in the methods and the various research is conducted across the world, to study the behaviour of point absorbers on the waves. The point absorbers such as wave buoys are designed to move according to the waves and the generator that is mechanically coupled with the buoys, generate electricity. But these buoys can also be used for measuring important parameters like the force acting on it due to the incident waves and their movement can be tracked to study the effects on the buoy due to the incident waves.  This project, as an extension of a previous work titled ‘Design and Development of a Measurement System to Track the Motion of a Point Absorber’ by Juliana Lüer, focuses on modifying and replacing the controller data acquisition and the communication system. The main aim is to increase the stability of the system and increasing the size of data storage and range of the data transmission. This is done in 3 steps that are as follows: - The Arduino based controller is replaced with an advanced Raspberry Pi based computer called RevPi Compact. - The Secure Digital (SD) card storage is replaced with a solid-state (Universal Serial Bus) USB memory stick with a large capacity. - The Radio Frequency (RF) based data transmission is replaced with a 4G (fourth generation) internet modem. The 60 W solar panels are retained from the previous project. But the Lead-Acid battery is replaced with two Lithium Polymer (Li-Po) batteries of 768 Wh capacity each. This increases the stability of the power source and enables the buoy to stay active for a longer time even when there is no useful solar irradiance for many days. There are two force transducers (strain gauge) to measure the line force and the angular force acting on the buoy. The Ellipse2-D Inertial Measurement Unit (IMU) from SBG systems is retained from the previous experiment. This sensor can track the Altitude and Heading Reference (AHRS) data along with the Global Positioning System (GPS) data with high levels of accuracy.  All the data collected are can be tracked instantaneously due to the 4G internet communication protocol and this is enabled by TelenorTM connection and HuaweiTM 4G modem. A copy of these data is also stored in a SanDisk USB memory of 500 GB capacity. The tests are carried out under the laboratory conditions and the outputs are as expected. The whole setup is to be installed in a metallic buoy and to be tested in the Lysekil test site in the future.