Energy efficient designs for in-situ charging of contactless embedded sensor nodes
The development, production and installations of IoT nodes increases further. These devices, equipped with sensors, ensure a better monitored environment. In the design, energy consumption is greatly reduced. Various techniques such as the reduction of data transfer, placing the MCU in sleep,…. are applied. The autonomy of this devices amounts usually a number of months or years. The battery will drain over time. Empty batteries can be prevented by implementing an energy harvesting system. Harvesting energy does not work in all places, such as in dark windless environments and can greatly increase the cost of the IoT modules. Therefore, there is a need for a system to recharge the nodes batteries. A movable power bank can offer a solution. Batteries from IoT nodes located in houses or cities can be recharged with a robot or drone. In the domestic environment, a robot, similar to a robot vacuum cleaner, can drive to different places to charge all kinds of devices. Think for example of lamps, Christmas lights,… . Hereby, power cables in houses can be avoided or reduced. In this PhD, the efficiency to charge such nodes is being investigated. The robot's choices will take into account the grid energy, the time of day, the priority of the IoT nodes, … . The robot itself can be equipped with an energy harvesting system to further increase efficiency. For example solar energy through windows can be transferred to devices. Another element in this context is the data transfer via a WPT (Wireless Power Transfer) link. IoT nodes in cities sometimes collect a huge amount of data. It is not possible to forward all this data with LPWANs. Local processing is recommended and only the results are forwarded. Assume that over time the battery of an IoT node is charged by a robot / drone. At such times, the robot is available to receive or transmit a large amount of data via the (WPT) link. For example, IoT nodes where audio samples are collected to record noise nuisance in a certain neighbourhood. On the other hand, a software update could be performed, since this is usually not possible with the LPWANs. To realize such a system, there is a need for a WPT link where both large amounts of energy and large amounts of data have to be exchanged.