Team Members John Henderson Curt LaBarge Greg Pearson Yixin Qiao Client/Advisor Steve Holland (ISU Canoe and Kayak Club)

Design and build a low-cost stream depth gauge The gauge should be: – Self contained – Robust in the environment – Low maintenance – Low power – Capable of transmitting measurements wirelessly

Iowa flow levels change dramatically Current gauging strategies are inadequate – High Maintenance – At threat of cancelation – Cover a limited amount of streams and rivers Canoers and Kayakers need easy access to flow data to accurately plan trips Some waterways are currently not monitored Photo Credits: ISU Canoe and Kayak Club

Expensive – $5,000/yr to maintain Complex Design – Stilling basin – Two story structure – Under ground pipes – Electronic recorder Typical USGS Gauge Design Photo Credit: USGS

Total Price of Materials < $500 Measurement Accuracy: 1inch Operating Temp: -5°C to 70°C Survivable Temp: -40°C to 70°C Daily data transmission Power save during winter

Our design must withstand the following: High Winds Ice Floods Rain Snow Photo Credits last slide

Any object placed directly in body of water must withstand the following conditions: Ice formationsOther Floating debris Photo Credits last slide

Low maintenance cost Long battery life – Minimum: 1 yr Rugged design

Possible Choices: – Ultrasonic range sensor – Float System – Water Pressure Sensor – Air Pressure Sensor Absolute Differential

List of Choices: – Ultrasonic range sensor – Basic Float System – Moving parts easily break! – Water Pressure Sensor - Too expensive ! – Air Pressure Sensor Absolute – Not as simple as differential option Differential

Ultrasonic Pros: Long range (26ft) Withstands extreme temperatures Accurate to 1cm Cons: Complicated installation Difficult sensor placement Vulnerable to floating debris Relatively expensive ~ $100 Objects could get lodged under sensor, causing incorrect measurement Differential Air Pressure Pros: Inexpensive Withstands extreme temperatures Accurate to 1 inch Can be installed under water Cons: Under water tubing is needed to connect sensor to rest of the system Could lose accuracy due to air leakage Shorter range ~9 feet

Best option: Differential Air Pressure Sensor Why? – The sensor costs 1/10 th of the ultrasonic sensor – Can be placed underwater instead of above it – Could be buried under sand Sand can be used to protect the sensor – Leaves the team with more installation options and configurations

AIR Water level is proportional to air pressure inside cylinder As water depth over cylinder increases, so does air pressure Housing and tubing buried under a sand bank for added protection against floating debris Tube to Pressure Sensor

Microcontroller Cell Module Pressure Sensor Power Bus Charging Circuit Voltage Regulator Battery Air Water Voltage Regulator Solar Cell

The team will use the ATMega128 Why – Past experience – Can talk directly to cell modem through UART State machine style in our programming – will greatly help out in our debugging phase

Pros: – Easy to use – Commands given through UART Cons: – Poor signal strength We will choose a testing location based off of this – Prepaid Billing The more we test, the more we pay

Cell Module will “text” the ISU Canoe and Kayak Club with measurements – Measurements will occur once per day Microcontroller will: – Take pressure sensor reading – Convert pressure reading into water depth – Send data to cell module for transmission through UART

Determines the success of our project – Must be designed to keep system powered for an entire year – All components should contain as low leakage current as possible Foreseen issues we are currently dealing with – Snow build up on solar cell – Battery failure due to cold weather – Strict power budget

Power Circuit will consist of – 5 Watt solar cell – 2 6V Lead Acid Batteries Charging circuit – 3 Voltage regulators will be used to keep Microcontroller and Cell Module’s input voltage constant

System Power On Consumption: Telit GM862-GPS Wireless Modem: Voltage: 3.8 V Current: 200 Ma Atmel ATMega128 Microcontroller: Voltage: 2.7 – 5.5 V Current: 20 mA Freescale MPX2050 Pressure Sensor: Voltage: 16 V Current: 6 mA National LM284X Voltage Regulator: Power on: Vshutdown = 2.3 V Quiescent Current = 1.85 mA Leakage Current =.5 uA System Standby Power Consumption: National LM284X Voltage Regulators: Quiescent current = 40 uA Leakage Current =.5 uA ATMega128 Microcontroller: 10 – 15 uA

Extensive research on: – Possible Environmental Conditions – Different options for measuring water height – Power Requirements We have purchased the following: – Microcontroller – Pressure Sensor – Cell Module – Under-water tubing – AT&T SIM Card – Solar Cells and Battery

Test individual components such as: – Cell Module – Microcontroller Waiting for Evaluation board – Pressure Sensor Designing power system – Choosing components based off of 5Watt power budget

Test Power System Components Construct Under Water Housing component Program microcontroller and cell module Put system together Create working prototype by spring thaw Upon Spring Thaw: – We will field test our prototype in a local stream

Our team will test the following: – Accuracy of water height measurement – Air leakage in under water housing unit and tube – Power Management Can solar cell keep system charged up for a year? – Wireless signals – Max and Min operating temperatures – Overall ruggedness of system Will the system hold up to extreme weather conditions such as rain, snow, hail, wind?

Microcontroller and Cell Module have arrived Power Components have been ordered Under water housing has been designed and will be built in the coming weeks Software implementation has been researched and test code is currently under development

The team is working hard to complete a working prototype by spring thaw – This goal has been set by our advisor who has stressed this goal since day one – Field testing our system is vital and will be used to point out any weaknesses our system might have that controlled testing could not.

Brief Summary Stream depth gauge Components – Pressure sensor – Microcontroller – Cell Module – Power Circuitry Major Tasks – Implement code – Build prototype by spring thaw ? ? ? ? ? ?

“High Winds” “Rain" “Floods” “Snow” “Ice” “Ice Formations” “Other Floating Debris” All other images were taken from Microsoft Office Clip Art