Micro-energy harvesting by pptfiles


									         Micro-energy harvesting
• Testing the feasibility of
  indoor harvesting from
  routine motion in the
• A comparison of three
  energy harvesters gathering
  from linear motion produced
  by a sliding door.
• Looking at piezo elements,
  stepper motor generator and
  faraday induction.
          What is energy harvesting?


Energy harvesting (also known as Power harvesting or energy scavenging)
is the process by which energy is captured and stored. Frequently this
term is applied when speaking about small autonomous devices, like those
used in sensor networks. A variety of different sources exist for harvesting
energy, such as solar power, thermal energy, wind energy, salinity gradients
and kinetic energy.
          Piezo electric elements
• It is the inherent property of piezo electric material to
  produce an electrical potential, high voltage - low current,
  when put under strain, either deflection or compression.
• Used both micro-fiber composite (mfc) and traditional
  ceramic types.
       Stepper motor generator
• Produce power at low rotation rates
• Produces twice as much power as a dc motor
• Common and easily available
    Electro-Magnetic induction
          (Faraday’s law)
• Passing a magnetic field through a conductive coil
  produces an electrical potential.
• Utilized a commonly available “shake flash light”
  and circuit.
                    Early trials
• We initially worked on testing the feasibility of piezo
  energy harvesting to find a method of capturing the energy,
  rectifying it, storing it and measuring it.
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MFC piezo transducer
         - A woven fiber composite piezo -
           produces three times the current
           compared to a standard piezo.

         -needs to be adhered well to a
          flexible substrate for optimal output

         -produced a cater lever with a counter
          weight for optimal deflection and
          energy output
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Data Logging: processing
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Graphing with mySQL + php

- Each Harvester has an xbee radio checking the
  charge of the capacitor from its analog i/o pin and
  sends the byte value and address in an api packet to
  a base station every 60 sec.
- The base station, running processing, pulls apart
  the api packet and logs the data by address into a
  mySQL database running on a server.
- A php script grabs the analog data, converts them
  into volts and then into joules and graphs them
         Xbee transceiver communication

      base station             joules1/2/3
atid 1955                      1955
atmy 0                         1/2/3
atdl 1                         0
atir 0x32                      0xEA65
Atit 0x1                       0x1
Atd0 -                         0x2
Atd2 0x3                       0x4
Atio 0x03                      -
Atic 0x18                      -
Atia -                         0x00
                      FlashLite phone app

-Pulls the last value from the
 mySQL database via a php scipt

-graphs the three values as volts
 as related to the xbee ref

- if a cap reaches the xbee max:
  app allows the user to press a
  button that places a call to the
  asterisk server.

-acts as a testing management
           Flashlite -> Asterisk -> Processing

1. FlashLite places a call to the asterisk server asking them
   to enter the extension.

2. User enters the dial plan where text to speech introduces
   them and explains the interface.

3. A shell scipt then launches a Java file: JEAGIClient,
   which grabs the call data.

4. JAEAGIServer.java runs on the server handing data back and
   forth between asterisk and processing.

5. Processing parses the key values from the server that then
  trigger an api at command to the local xbee.
               Writing api AT commands to the xbee
//api packet to be sent out HIGH
      port.write(0x7E);      //start byte
      port.write(0x0); //MSB
      int dataLength = 4; // set this to whatever your data length is currently
      port.write(0x1 + dataLength); //LSB=data length + API id + frame id + two command bytes
      int checksum = 0;
      port.write(0x08); // send API command identifier
      checksum = checksum + 0x08;
      port.write(0x01); // send frame ID (set to 0 if no response is required)
      checksum = checksum + 0x01;

    port.write(0x49); // at command i
    checksum = checksum + 0x49;
    port.write(0x4F); // at command pin2
    checksum = checksum + 0x4F;
    port.write(0x08); //set pin high
    checksum = checksum + 0x8;

     println("Pre-checksum: " + checksum);
    checksum = 0xFF - checksum;
    println("checksum: " + checksum + " <-- this must be a single byte!");
    port.write(checksum); //checksum
    println("sending api packet to xbee!!!");
             General Conclusion

1. Indoor energy harvesting is both feasible and necessary.

2. It is also very inexpensive and readily available.

3. All indoor environments have objects in routine motion, such
   as doors opening and closing that can be converted to electrical
  Conclusion: piezo harvesting
1. Piezo harvesting was the least effective form that we tested.

2. The frequency of deflection necessary to produce a usable amount
   was not possible from installation on a door.

3. Effective Piezo transducers and costly: $160+ per

4. They produce very high voltage spikes and very low current,
   thus, a perf- board was required rather than a bread broad due the
   instantaneous rate of change.

5. Reasonable deflection was not possible from vibration so flicking
   became the preferred means results in noise.
Conclusion: stepper motor generator
1. The greatest amount of energy was attained via the motor as
   linear motion was transferred to circular.

2. Quickly 5volts was able to be stored in a . 33F cap.

3. Leakage of the cap was a problem as energy stored and released
   are both exponential.

4. Cheap and readily available, small package and no extra noise.
Conclusion: electro-magnetic

1. Great potential to produce electricity, but a door was not the
   right environment due its requirements for linear motion
   and high frequency.

2. Very cheap and easily produced.
Link to resource wiki

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