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