2. 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.
3. For modeling this concept we need the
following parameters
Mechanical
Magnetic
Geometric
Analog circuit components.
4. 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 node
Energy consumption model dependent on
operation Equivalent variable resistance
5. 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.
6.
7. 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.
8.
9. 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.
10. 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.
11. 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.
12. 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.
13. Wireless sensor networks are fast developing.
Wireless sensor system by tunable energy
harvester have attracted research interest.
This is first HDL-based modeling approach.
