WIRELESS SENSOR BY TUNABLE ENERGY
HARVESTERS
PRESENTED BY RAMYA
MAGESH
INTRODUCTION HDL approach for modeling a wireless
sensor node system powered by tunable harvester.
Tunable energy harvesters can adjust its
own resonant frequency by mechanical method.
MODELING APPROACH
For modeling this concept we need the following parameters
Mechanical Magnetic Geometric Analog circuit components.
Component Behavior modeled Model abstraction level
Microgenerator Interactions between mechanical, magnetic and Nonlinear differential equations
electrical domains with component geometry
Accelerometer Analog input acceleration converted to output Ordinary algebra equations and
measurement and energy consumption model equivalent variable resistance
Tuning actuator Digital input drive signal converted to output Ordinary algebra equations and
analog tuning force and energy consumption model equivalent variable resistance
Power processing Nonlinear analog circuits Nonlinear differential equations
Tuning controller Digital control algorithms and energy SystemC digital processes and
consumption model dependent on operation equivalent variable resistance
Sensor nodeEnergy consumption model dependent on operation Equivalent variable resistance
WIRELESS SENSOR NODE The wireless sensor node system consist
of 1)Micro generator-provides the
vibration input. 2)Power processing-converts
vibration into electrical energy and stored in capacitor.
3)Tuning controller-controls frequency tuning of micro generator.
4)Sensor Node-Samples the supply voltage.
5)Temperature sensor-Transmit these data to a receiver.
TUNABLE MICRO GENERATOR
The micro generator is based on cantilever structure.
Tuning mechanism changes stiffness of the cantilever that change resonant frequency.
The frequency of micro generator is equal to frequency of ambient vibration.
m(d^2)z(t) + c dz(t) + kz(t) (dt^2) dt This equation ensures the accuracy of the
model.
ENERGY-AWARE SENSOR NODE The sensor node monitors
environmental temperature and capacitor voltage.
Once activated it transmits the temperature and voltage value via radio link.
To characterize energy consumption model of sensor node, its current draw was measured.
TUNING CONTROL The timer wakes the tuning controller
periodically checks for energy storage.
If energy present-its tuning control will detect the ambient vibration frequency.
If energy not present- tuning control goes to sleep and wait for next timer.
HDL IMPLEMENTATION
This system incorporates both analog and digital components.
ANALOG COMPONENTS: Analog and mixed signal is used to build the
analog models. Non-linear differential and algebric eqns.
Energy budget is essential.DIGITAL COMPONENTS: Algorithms are prepared for i.)Tuning control process. ii.)To get data. iii.)Movement of actuator.
SIMULATION RESULTS Experimental measurement carried on
this system and compared with this result.
The energy is generated and consumed.
Once tuned, the generator is able to begin charging the capacitor.
The relative error may occurs, even though this process is successfully simulated.
CONCLUSION Wireless sensor networks are fast
developing.
Wireless sensor system by tunable energy harvester have attracted research interest.
This is first HDL-based modeling approach.
JUDGES AND STUDENTS