1. “Cell Packing indicator”
Final project for AE504 “Instrumentation for Agricultural and Biosystems Engineering”
“Cell Packing indicator”
Lidia Esteve Agelet & Delise Lockett
6 December 2007

2. - Learning about instrumentation and data acquisition systems
PURPOSE OF CLASS PROJECT
- Learning about instrumentation and data acquisition systems
FINDING A PROJECT…
Noticed different ways of pouring grain samples in cells
Different packing grade is proven to influence NIR spectra
Packing density influence absorption!
THE IDEA
Build a set up that allow to determine the packing level of a product cell using lights and sensors

3. SET - UP SET - UP Choosing and setting the lights
1) Must pass through the grain at different intensities : Infrared
2) Narrow wavelength range emitted and small half intensity beam angle: GaAlAs Laser Emitting Diodes (LED)
3) Wavelength not so relevant in calibrations but also commercially available
4) Not much power required
5) Small current needed – require resistances - 5V
100

4. SET - UP SET - UP SET - UP Choosing and setting the detectors
1) Must match the LED in wavelength and intensity
2) Sensitive enough to detect light intensity after 2 cm of grain
3) Signal had to be amplified twice: 2 op-amps plus resistors (Gain)
4) Amplifiers require +-15V to be enabled

5. SET - UP
Use of a “PMD” to collect the analog data from the detectors and send it to the computer through VB programming

6. SET - UP
Product to test : Soybeans
Cerea instrument sample cell

7. CALIBRATING THE SENSORS
Working with raw sensor data
Average of 1000 readings from each single sensor (6 readings/sensor/sample)
Samples:
Ground
Halves
Whole soybeans
Mixtures 50-50%
Readings also after 15 seconds shaked
GOOD PACKING: All shacked samples, ground samples. Lower limits.
BAD PACKING: Whole soybeans, wet soybeans. Upper limits.
UNKNOWN: Halves, mixtures

8. CALIBRATING THE SENSORS
From the means, we created 3 reading categories:
- Good : Below lower limits
- Bad : Above upper limits
- Unknown: The overlapping of lower-upper limits
- The combination of each category and each sensor, must provide a final result or packing level.
Total number of combinations = 27

9. THE PROGRAM

10. THE PROGRAM Advice/comments Average of 100 readings
Packing category following the logic tables
Advice/comments

11. THE PROGRAM Multiple readings option: More realistic results
3 readings each sensor
Ask to change the cell position after each reading
A solution to cover as much surface as possible without using too many LEDs and detectors
Follow the same decision table

12. Thanks CONCLUSIONS/FINAL THOUGHS
Seems too work pretty consistently if the calibration is adequate
Need to try more grains, different calibrations for different grains are expected to be needed
Could improve: Using filters/lens, LED controller, more LEDs-detectors (?)
Possibility of working with absorbance values instead of raw voltages
Unknown effect of sample composition over the readings
Unknown scattering effects and light behavior
Thanks