Measuring Stream Velocity with Wireless Probes

The goal of the project is develop Bluetooth technology that can communicate wirelessly with 2 or more conductivity probes to measure small stream velocity. With the readout of the probes, probe settings, and software be accessible from a tablet or smart phone.

=Problem Definition=

Background


Measuring velocity in large stream channels have use a variety of successful means from current meter to acoustic devices. However these instruments do not work well in narrow, shallow, steep stream channels. For these shallow small streams various methods have been used. The simplest method uses a tennis ball or equivalent that is timed over a set distance. Small current meter are used but sometime are only partially submerged thus do not provide reliable measurements.

We currently use two conductivity probes connect with wires to microprocessor and a laptop computer. A salt solution is added to the water and salt solution pulse measured as it passes by the two probes which are separated by a set distance (2-4 meter). We use software to read and graphically-observe the microvolts readings of the conductivity probes which is related to the salt concentration. This technique has been successful on small streams and even shallow rill flow on hillslopes.

Specifications

 * '''Stream Velocity
 * 2 L/min to approximately 4 cfs
 * '''Range of Communication
 * Approximately 6 stream widths between the probes
 * Bluetooth readings 100ft away from probes
 * '''Software
 * Peak to Peak calculations
 * Integration of curve with 5% error
 * Data exported to Excel for tablet access
 * Wireless data acquisition
 * 8 reading per second from each probe
 * At least 2 probes reading simultaneously
 * '''Additional Specifications
 * Lightweight
 * Long battery life
 * Weather proof housing
 * Withstand extreme temperatures

=Design Development= There are three main areas of design, the circuit, the app, and the housing. The probe circuit will take the measurements, and do all the calculations before sending the data to the app. The app will receive the data from the circuit and have a user interface so the data can easily be read in real time. The probe housing will hold the circuit and must be waterproof and durable.

Probe Housing
Probe Housing Parts:

=Final Design=

Circuitry
Circuit Schematics

Probe Housing
Drawing Package

Final Assembly
In the final assembly, you can see that the electronics are now attached to the cap, and can be easily inserted into the handle of the probe housing. The guard on the end of the extendable rod was also lengthened because the probes stuck out further than anticipated. The excess wire unfortunately must be wrapped on the outside of the housing because we were unable to get a reel system working in time.

=Conclusions=

Challenges
The biggest challenge that we faced in this project was designing a reel system for the wire to spool up nicely when the extendable rod gets collapsed. Our first idea was to just have the wire bunch up on itself in the excess space in the handle, but the pin got in the way so the wire just bunched up in the extendable rod and got the entire rod stuck. Our second idea was to design and 3D print a fishing reel type contraption, but we also had problems with this design. The main problem with this design was that the wire would catch on the spool and then get the reel jammed. We also had problems with the wire twisting and making it impossible to reel any further. Our main problem with designing the reel was the space constraint inside the handle and reducer, and that we were also running out of time to work on the project.

Recommendations
In future iterations of this project, here are some of the recommendations of things that we think should change or be added: Have the circuitry have its own housing inside the handle.
 * This will allow the circuitry to be even more water proof in case the handle or any of the sealant cracks
 * It would also give the circuitry its own space, and not just be in the big handle bouncing around
 * This would allow the circuitry to be much more secure to the cap, as we are just using the 9V battery snaps to hold it in which isn't secure

Add a reel system
 * We believe that adding a spring loaded reel system would fix the problems that we encountered when designing the reel
 * A spring loaded reel would also make it so the operator would never have to manually reel the wire in

Have wires be more easily attachable/detachable from the circuit board
 * In our design we have all the wires soldered directly onto the circuit board, and on several occasions the wires have broken off and needed to be resoldered on. To temporarily fix this problem hot glue was put on the wires to remove the stress from the solder points
 * Having screw locking wires would also allow you to change the configuration of the wires if you had any changed in the code, or just replace wires more easily.

=Team Members=

=Additional Documentation=

Project Schedule

| Schedule

Presentations

Snapshot 1 Design Review(Embedded video no longer works, see link below) Snapshot 2(Embedded video no longer works, see link below) Engineering Release Review Snapshot 3 Technical Presentation(Embedded video no longer works, see link below) Poster

Videos

| Snapshot 2/Design Review Video | Technical Presentation App Screen Recording

Other Documentation

| Budget | Design Validation