Energy Efficient Sensor Nodes Powered by Kinetic Energy Harvesters – Design for Optimum Performance

Abstract

Abstract-In an energy harvester powered wireless sensor node system, as the energy harvester is the only energy source, it is crucial to configure the microcontroller and the sensor node so that the harvested energy is used efficiently. This paper outlines modelling, performance optimisation and design exploration of the complete, complex system which includes the analogue mechanical model of a tunable kinetic microgenerator, its magnetic coupling with the electrical blocks, electrical power storage and processing parts, the digital control of the microgenerator tuning system, as well as the power consumption models of sensor node. Therefore not only the energy harvester design parameters but also the sensor node operation parameters can be optimised in order to achieve the best system performance. The power consumption models of the microcontroller and the sensor node are built based on their operation scenarios so that the parameters of the digital algorithms can be optimised to achieve the best energy efficiency. In the proposed approach, two Hardware Description Languages, VHDL-AMS and SystemC-A is used to model the system's analogue components as well as the digital control algorithms which are implemented in the microcontroller and the sensor node. Simulation and performance optimisation results are verified experimentally. In the development of the fast design exploration tool based on the response surface technique, the response surface model (RSM) is constructed by carrying out a series of simulations. The RSM is then optimised using MATLAB's optimisation toolbox and the optimisation results are presented.

Modeling Single Flexible Link Using Hardware Description Language

“…For example, in [11] VHDL-AMS is used for fault modeling of analog circuits, where part of the system required modeling in MATLAB. Also in [12], VHDL-AMS is used to design energy efficient sensor nodes optimum performance and then MATLAB optimization toolbox is used. The current HDLs are not flexible in the sense that designers cannot reuse libraries written in C++.…”

Conventional and sub-threshold operation regimes of CMOS digital circuits

“…Since the energy harvester system takes a lot of time to collect enough energy from the environment, it is reasonable that the time interval needed for data processing can last much longer than usual, up to microseconds or, even, miliseconds [4], [5].…”

“…There are several ways to generate electrical energy locally, such as making use of the kinetic energy of vibrations widely present in the environment, photovoltaic or thermoelectric effects provided there is sufficient incident light or temperature gradient, respectively. Except for vibrations, there are other kinetic energy harvesting applications where the electrical power is generated from footstrikes, knee bends and backpacks [4] [5].…”