Rain Gauge Retrofit

The rain gauge retrofit entails modifying current rain gauges throughout the northwest to store data in electronic form, saving time and money for the US forest service.

Why make a conversion for rain gauges?
Currently, each rain gauge requires an individual to laboriously convert data on a piece of paper to data in programs such as excel. There are many of these gauges throughout the world, and most still rely on the older designs utilizing paper rolls. Converting the initial data collection to electronic form could save on quite a bit of man-hours, allowing the forest service to use those man-hours elsewhere.

Current methods
There are many small variations in design, but they all work on one basic premise: physical movement of an actuator arm, combined with an internal tension spring. Calibration is relatively simple: the recording paper is marked to give reference numbers regarding rainfall in fractions of an inch, and the system is balanced using various sets of weights until the actuator arm accurately reflects real rainfall amount.

Specifications
Team Rainmen Specifications

Electrical Engineering
Noise Analysis Goals:


 * Confirm a linear behavior between displacement and voltage
 * Detect any possible electrical noise/interference that may cause problems with accuracy
 * Become more familiar with a critical part of our proposed retrofit design

Results:


 * A linear behavior was observed, plotting a curve to fit data should be relatively straightforward
 * Interference was not present. There is a certain level of variation in voltage level with the potentiometer at the same displacement, but this can easily be remedied.
 * The team as a whole became more familiar with the proposed equipment.

Power Analysis Measuring Power Consumption No power saving enable constantly running and polling data. Draw = 13.3 mA

In order to meet client’s needs to last six months required mA of battery: 56 Ah!!!! That’s huge and very expensive. Something has to change.

Power saving implementation. Taking advantage of power saving features of the microprocessor. Power draw with power-saving enabled and no indicator LED: Draw= 1.4mA Using 4 AA batteries (6 Ah) Using 3 18650 li-ion cells (7.8 Ah) Approximate operational life: 192 days or 6.5 months The specifications can realistically be met
 * standard alkaline battery is 1500 mAh costs $0.50 each
 * each cell is 2600 mA costs $5.00-$10.00 each

Validating Rotary Potentiometer Having selected the rotary potentiometer to move forward with design we needed to validate its range of operation and maximize the useable range.

This graph compare the rotation used to the measurement resolution achievable. The y axis is the resolution in mm, customer specifications require under 1 mm. The x axis is degrees of ration in radians. Current set up Design Goal Exceeding customer’s specs Hoping to accomplish through gearing.
 * Resolution = 0.89 mm
 * Meeting the customer’s specs
 * Resolution = 0.3mm

This graph compare the rotation used to the measurement resolution achievable. The y axis is the resolution in mm, customer specifications require under 1 mm. The x axis is degrees of ration in radians.

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