DIY 360 Degree SODAR Device

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Introduction: DIY 360 Degree SODAR Device

First off, why did we decide to call this thing SODAR? SOnic Detection and Ranging, or SODAR, is a lot like SONAR and RADAR. However, we don't feel comfortable calling it SONAR because we have no desire to use it for navigation and we aren't under water. Also, it's definitely not RADAR as we are using ultrasonic pulses, not radio waves to find objects. 

With the technicalities out of the way, here are the project's objectives:
 1) To create a freely rotatable SODAR system that can continuously detect objects
 2) To create a UI that displays objects similarly to radar
 3) To make it as portable as possible

To accomplish objective #1, we need a way to prevent wires from tangling while the motor spins. There are two ways that we thought would be relatively easily implementable. The first method would be to use two Arduinos and transceivers for a wireless transmission of data from the spinning platform to the computer for display. The other method would be to use something similar to a rotating electrical connection (REC), where the electrical connection would be maintained using a conductive liquid at the intersection. 

While it seems to go against objective #3, we decided to go with the rotating electrical connection idea. This is mostly because we didn't know if it'd work and wanted to try something new. On top of this, commercial slip rings are upwards of 20 dollars (price found by ellisgl) and we wanted to see how hard it would be to make a reliable REC. In our project, we are using a vinegar-salt solution as an electrical conductive liquid because it is functional and inexpensive.

Future Work Suggestion:

Use wireless transceivers so the project can be placed in one area and send data to the laptop in another area.

Collaborator:

Electrical circuit designer/builder extraordinaire: intensePancake

Step 1: Get Materials

Non-electrical materials:

1) PVC couplings - 2", 3", and 4" diameter
2) PVC Bushing - 1"X3/4"
3) Household Goop adhesive (water-proof)
4) Gorilla glue adhesive
5) Elmer's glue adhesive
6) 12" x 12" commercial vinyl tile
7) 6" diameter cylindrical styrofoam
8) Balsa wood: 1/2"x1/2"x36", and 3/8"x3/8"x36"
9) Fun tack
10) Coupler (we used a pen body)
11) Extra cardboard (from packaging, etc)
12) Clear tape
13) White vinegar
14) NaCl
15) 3/4" Dowel

Electrical materials:

1) Arduino Uno board
2) Parallax PING))) Ultrasonic Distance Sensor
3) Stepper motor
4) SN754410 H-Bridge motor driver
5) LM7805 5V voltage regulator
6) 100μF electrolytic capacitor (1)
7) 100nF capacitor (1)
8) Perforated board (1)
9) 9V batteries (2)
10) 9V battery connectors (2)
11) alligator clips (2)
12) connection wire
13) soldering iron and solder
14) solderless breadboard

PVC sidenote: We bought 4 PVC pieces thinking we would need 3 spaces for liquid electrical conductors (ground, power, signal), but we found that our vinegar-salt solution couldn't transfer 5V to the sensor, so we only ended up using two sections and put a 9V on the spinning platform.

Step 2: Cutting and Drilling

We are writing these instructions the same way we made the SODAR but this is a reminder that we only ended up needing 3 PVC pieces.

PVC editing:

Using a miter box, saw the PVC so that all 4 PVC pieces are the same height. In our scenario, that would be approximately 1 & 3/8" in. Afterwards, level the PVC bases with coarse grain sand paper so that it would be flush against the tile.

Tile editing:

Cut a 6" x 6" piece off to use as a base for the PVC. From the center of the piece, mark the outer edges of the 4 PVC pieces with a compass. Then drill a central hole atleast 5/16" and three holes for the wires at 1/16" (one hole per section).

Step 3: Gluing: PVC to Base & Balsa to Styrofoam

Secure the PVC

With the goop, glue wires with stripped ends into the 1/16" holes that were drilled into the tile. Glue these so that about an inch of exposed copper is above the tile and at least a foot of sheathed wire protrude below. Afterwards, apply an even, thick layer of Household Goop on the bottom of the PVC pieces and secure them to the 6" x 6" tile. Use the outlines drawn in the previous step for proper placement. Make sure that each wire is only in its own section (to prevent shorts in the circuit) and that there are no gaps in the glue that liquids could pass through (and short the circuit). Let the goop dry as described in the instructions. 

Secure the styrofoam

Find the center of the styrofoam with a ruler and poke a hole through the middle with a pin. This pin will act as a guide for centering the coupler. In our scenario, we dug through our pens searching for a pen body that fit somewhat snugly to the stepper motor shaft. Once the coupler is centered on the styrofoam, secure 4 6" pieces of 3/8" x 3/8" balsa wood around the coupler with Gorilla Glue. Do not glue the coupler into the center yet. The balsa wood design is shown in the picture.

Note: You may want to clamp the balsa wood down or put something flat and heavy on top of it to prevent the Gorilla Glue from expanding in such a way that the balsa wood is not level. Also, since you will be putting the coupler into the center of this later, be careful not to use too much Gorilla Glue or risk filling the center piece when it expands.

Warning: There are a good amount of strong adhesives out there that will eat through styrofoam (think napalm-like reaction). We first tried adhesion with the household goop and, needless to say, we had to go buy a new 6" styrofoam piece.

Step 4: Test for Water-Tight Seal

Fill the sections with water, looking for any leaks. If you want to, you can fill all three and then put a drop of food coloring in each looking for cross bleeding. In our scenario, we did this step after Step 5, but a leak would be much less damaging if found before that step so we recommend doing the test at this point.

Step 5: Add Lower Platform

With the upper platform flipped so the tile is on top, place the stepper motor shaft into the center hole. Cut eight 3" long 3/4" diameter dowel pieces as spacers between the upper and lower platforms. Using Goop, glue four of the pieces so that the motor is stabilized. Glue the other four farther away from the center so that the weight is more evenly displaced. Glue a second 6" x 6" piece of the tile to the bottom of this and let it dry. It is best to have the motor securely flat against the bottom tile.  However, if you don't want glue on the motor (like us), and lift it, you run the risk of having to put small spacers to level is after everything dries (like us). The picture shows the piece after this step with the uncut coupler (a pen with fun tack).

Note: An alternative to this step would be to not have the innermost PVC piece (since only three are needed), and instead have the motor up, level with the PVC on the initial tile base.

Step 6: Binding Bottom to Top

Cut the coupler:

Measure the length of coupler (pen) that you want to use, including a gap between the PVC and balsa wood. In our project, the gap was 1/2". 

Binding the pieces:

Add Gorilla Glue to the center of the styrofoam, between the 4 balsa wood pieces. Place the styrofoam upside down so the balsa wood is facing up and put spacers between the balsa wood and PVC (we used 3" x 1/2" x 1/2" balsa wood pieces). After securing the coupler to the stepper motor shaft, place it on top of the styrofoam. The weight of this piece will prevent the expansion of the Gorilla Glue from tilting the styrofoam relative to the coupler.

Step 7: Downloading Code

Arduino, Processing, and Our Code

To control the SODAR device, the Arduino must be correctly programmed, and the computer must communicate with it through the serial port. We have written Arduino code and Processing code to do just that, and it's all available at our GitHub repository.

Stepper library

In order to get the required angular functionality from the stepper motor, we have made some custom additions to the Arduino stepper library. The updated library supports all of the same functions as the default stepper library. It is included in the libraries/Stepper directory in our repository. Just find the libraries/Stepper directory that Arduino uses and replace it with the new one.

NewPing library

For smooth operation, we also implemented interrupt-based PING sensor code using the NewPing library, available for download here. Download this and place it in the libraries directory of your Arduino sketchbook.

Note: The Arduino code must be uploaded to the board before running the Processing UI because the UI takes control of the serial port.

Step 8: Controlling the Stepper Motor

An Arduino Uno was used to control the stepper motor. Follow the schematic to connect the Arduino to the motor driver, and the driver to the stepper. The motor can be driven by a 9 volt battery, and our current measurements show us that battery life is about 1.5 hours of continuous use.

The "GND" and "PING))) Signal" wires are the same wires that were glued through holes in the tile in Step 3. These are for communication between the Arduino and the PING sensor. For an easy connection, put alligator clips on these wires, and use them to finish the connection. Now, one end of these wires should be in the vinegar-salt solution chamber, and the other end should have an alligator clip on it.

After building this circuit, you should be able to control the motor with the Arduino Stepper library.

Step 9: Connecting the PING))) Sensor

Building the circuit

Follow the schematic to build the PING Sensor power supply circuit. Solder it together on a perforated board for stability. This circuit will go on top of the rotating platform, and will supply a constant 5 volts to the sensor. The capacitors are there to stabilize the input and output and minimize electrical noise.

The two wires that lead into the circuit, "GND" and "PING))) Signal", must be long enough to make it through the styrofoam and into the salt-vinegar solution below. For us, they needed to be about 7 inches long. When in doubt, though, it's always better to cut them long and adjust them later.

Mounting the board

Once this circuit is completed, place it on top of the styrofoam platform. You may need to angle the sensor upward so that it doesn't only see the platform. We secured the circuit board to the styrofoam with extra pieces of wire that we stuck into the styrofoam. These weren't electrically connected to anything. We also made a 9V battery holder from a piece of cardboard and clear tape, and glued it to the styrofoam with normal Elmer's glue to keep it there.

Step 10: Final Construction

Vinegar-salt solution

Add salt into about one cup of white vinegar, stirring constantly, until the solution is saturated (no more salt will dissolve). This liquid can conduct electricity. Pour it into the PVC chambers to an acceptable height. There needs to be enough to touch both wires in each chamber as it spins. There should be no leakage, especially after testing in Step 4.

We noticed that when a current was running, many bubbles formed at the wire in the vinegar-salt solution due to hydrolysis reactions.

Note: When pouring the solution into the chambers, the rotating platform should probably not be attached.

Reattaching the platform

If your coupler is a pen (like ours) or a similarly shaped object, there is likely a gap between the inner walls of the coupler and the motor shaft. To alleviate this problem, we used fun tack to secure the coupler. To do this, put some fun tack into the bottom end of the coupler before placing it back on the motor shaft. Slowly push the coupler onto the motor shaft, possibly holding it with needle-nose pliers, until there is about a 1/2" gap between the PVC and the balsa wood.

Connecting through the vinegar-salt solution

In Step 9, we made the signal wire and ground wire coming out of the PING sensor circuit long. Guide those wires through the styrofoam into their respective chambers so the exposed ends are in the vinegar-salt solution. The integrity of this connection must be maintained throughout rotation of the platform, so make sure enough wire is touching the solution.

Step 11: Final Product

Four Little Things

1) Connect the Arduino to your computer through a USB cable.
2) Program the board with the Arduino code from our GitHub repository.
3) Connect both 9V batteries to the battery holders.
4) Start the Processing code.

You are now running a portable SODAR device capable of detecting objects up to 300cm away in any direction. Congratulations!

Arduino Contest

Finalist in the
Arduino Contest

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Participated in the
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1 Person Made This Project!

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107 Comments

0
burstolava
burstolava

Reply 13 days ago

Great to hear! There are a few changes you'd have to work out to the hardware and software since you're working with a sensor with..what is it 6 wires? That sensor may be compatible with the NewPing library, but I'm not sure and can't easily find a source to confirm if it can on Google. Obviously the slip ring would also need more compartments to account for all those wires, you may want to consider buying a slip ring instead of trying to make so many compartments (e.g. https://www.adafruit.com/product/736?gclid=Cj0KCQiAvP6ABhCjARIsAH37rbRBHsAFi12Yi4_AoEbBhpVmssGU6gDJn4I3NnrCoJnM6e27Ols35eUaAmWGEALw_wcB) . Sorry I can't be of more help, but if you do figure it out, please post back with what you did to make it work.

0
mukulmagotra98
mukulmagotra98

Question 1 year ago

hii i am using the same kind of project can u tell me what all changes do i have to make to make it a wireless system so that entangling of wires is not an issue ... i was thinking is it possible to use a bluetooth module hc05 for that purpose i am using a arduino uno , uln2003 driver , 28 byj stepper motor (5 wires), ultrasonic sensor hcsr04, please help me out in all the changes required for the arduino ide and processing 3

0
burstolava
burstolava

Answer 1 year ago

Hey, the PVC slip ring that we built in this project is to avoid tangling the wires as you rotate the sensor. No need for a Bluetooth module unless you want the whole apparatus to be separate from the computer that you are displaying from. I’ve explained how to use the HC-SR04 sensor in another comment below if you would like to look at how to use that instead of a PING sensor.

What are the five wires on your stepper motor each labeled as / how are they different from our stepper motor?

0
mukulmagotra98
mukulmagotra98

Reply 1 year ago

i want the whole apparatus to be separated from the computer ...that a requirement of mine ..tell me how can i do that

0
burstolava
burstolava

Reply 1 year ago

I have not done it, but I assume that because we are already using the serial library to accomplish communication that you may only have to connect the bluetooth to the Arduino, and maybe change a little of the processing code to use the correct communications for the bluetooth (e.g. 'arduino =newSerial(this, Serial.list()[0], 9600);' would have to be something else). I don't think you would have to change anything for the Arduino code if you hook up the bluetooth module correctly, but you may. Good luck with this!

0
mukulmagotra98
mukulmagotra98

Reply 1 year ago

can u tell me of someone who can tell me what to change, i also think so that only the start of the code needs to be changed but in what that i dont know . That serial data needs to be communicated via a bluetooth so that it goes to standalone type ..can u suggest me someone who can do so.
thank u regards

0
John135
John135

5 years ago on Introduction

Hi..

Is there anyway to use HC-SR04 sensor instead of ping? I can't seem to find it in my country and importing it costs around 65$

1
burstolava
burstolava

Reply 5 years ago on Introduction

There would be some changes to the project you would have to make because the HC-SR04 looks to be a 4 pin sensor instead of 3 pin. But the NewPing library supports the HC-SR04, so you should be able to use it.

0
fdrlalo96
fdrlalo96

Reply 1 year ago

Hola, como debo de manejar los pines, por separado?

0
burstolava
burstolava

Reply 1 year ago

If you are talking about the HC-SR04 4-pin setup, I think I have a simple way for you to get it to work. In the project, we had 3 chambers for liquid-connections, but had to put the battery on the top because not enough power would transfer through the liquid interface. So we only used 2/3 chambers with the PING sensor. But you could use all three chambers for the 3/4 pins in the HC-SR04, and put the battery on the top of the system, like we did. You would have to only slightly modify the code to get this to work.

0
burstolava
burstolava

Reply 1 year ago

If you're talking about the serial.ino + sodar.ino files, you have to open them both in a single Arduino sketch to upload both to the Arduino.

0
erguro
erguro

2 years ago

Dear Burstolava

I know there is a long time from the last post, I´m trying to build this awesome project, It seems Arduino and hardware are working properly but when I play UI at processing radar is stopped I mean the green part is stopped in the right side of the window 90 degrees with no motion I write start but stills same

I checked that Arduino is sending data, stteper motor is running and I can hear those small clicks from the SRF05 ultrasonic transducer so seems everthing it´s ok

Could you give me some advices ?

Thanks in advance

Best regards

window_processing.jpg
0
fdrlalo96
fdrlalo96

Reply 1 year ago

Hola tienes la librería paso a paso modificada es que no la he podido descargar, te lo agradecería mucho.

0
burstolava
burstolava

Reply 1 year ago

The modified Stepper library is in the GitHub repository. It is in the folder titled libraries/Stepper.

0
burstolava
burstolava

Reply 2 years ago

The green part moves based on the angle that the Arduino specifically states through the serial communication to the computer. Maybe the Arduino serial port is not defined correctly by the UI? Have you tried changing the line in the UI.pde file "arduino =newSerial(this, Serial.list()[0], 9600);"? To change it to Serial.list()[1]....

0
erguro
erguro

Reply 2 years ago

Finally I solved, it was an Issue with the serial port

0
DalaisL
DalaisL

Question 2 years ago

1.Hola me dejo Asombrado y me inspire para un proyecto en mi clase no tengo experiencia alta en arduino pero mira mi problema es este

1 como la conecto e forma inalambrica

2 como añado un parlante de 8ohm 1w que pite diferentes tonos a medida que hacerca el objetivo

me puedes decir si hay que cambiar algo en código

Felicitaciones y sigue así tienes muy buenos proyectos

por favor rapido

0
burstolava
burstolava

Answer 2 years ago

We did not implement wireless connectivity in this project. That was a suggestion for making the project even better than it is now. Unfortunately, the only way that I can think of how to add the speaker as you describe in #2, I think you would have to connect it to the Arduino and modify the code for this specific purpose.

0
p3rikitu
p3rikitu

3 years ago

Hi dear, i am doing a school work based on your project. The main differences between my project and yours is that my stepper motor will step 360 degrees to one direction and 360 degrees to the other in order to avoid all the construction that you build. I think i've managed to solve this issue but there's another problem. The sensor i'm using is a HC-SR04 which has a trigger and echo line. I'm a begginer in programming and I don't really know how I could change my program in order to make it work. Could you tell me which are the main parts i should modify in the arduino code related with the HC-SR04 and also I would like to know if something should be changed in the processing code. As I said i just modified the motor and the sensor and my last request is that i just would like to know if there would appear any more problems. By the way, it doesn't currently work, when i play the processing code, it goes crazy.