Sensors


#1

Are there any plans to add sensors to the electronics package? Interesting sensors (listed by difficulty of implementation) might include:

  1. Depth
  2. Heading
  3. Orientation/Position (accelerometer/IMU)
  4. SONAR

-Ben


#2

Ben, I was wondering the same question.

I'm a rookie when it comes to Arduino programming, but I do some RC FPV (First Person Video) flying and I have a great avionics package from Eagle Tree Systems. The systems is fairly simple and inexpensive, relatively of course. The data logger and OSD (On Screen Display) get info from various plugin sensors, GPS, engine RPM, TEMP Sensors, Airspeed and Altitude, and display it over the video image. It can't be too hard to ditch the GPS and substitute a compass module, and I bet the altimeter module could be reworked for depth. Position and orientation is another module that exist already so that shouldn't be too hard, although I don't know how the data is derived so perhaps it will be more difficult that I make it sound. SONAR is out of my league but that would be very cool.

I think with just a bit of work we could get Depth, Speed, Heading, Water Temp and Battery info (Amps/Volts) info directly displayed over the video feed.


http://www.eagletreesystems.com/OSD/OSD-Pro.htm


#3

Hello Ben and Ryan,

I'm also interested in adding some type of data logger. This project is very much akin to model rocketry aside from the medium being different. Some boards already used in rocketry could possibly be repurposed to our own uses. Slight reconfiguration might be required for depth vs altitude. They are already used to having minimal payload weight and small packages. Telemetry would have to be wired instead of wireless such as seen in RC planes and boats however.

Worth investigating.

-Claude


#4

I suspect that data logging will not be a problem - the Beaglebone can probably record data if we wish, or the topside computer (which will be probably be receiving telemetry data anyhow) can do it.

-Ben


#5

SENSORS is the most important part of the ROV

> System status (battery level, motor condition/speed, signal levels etc)

> Image - camera sensor (i.e camera) (already done)

> Pressure sensor (can be used for depth as well..)

> Gyroscope / accelerometer

> Positioning sensor (NOT ONLY DEPTH!) (distance, oriantation, depth) using new - ideas...(beacon etc)

> Temperature/salinity/ph/conductivity/turbidity

> Sound sensor (underwater)


#6

I definitely think all of this is needed. But I think we as a community should build and experiment with those stuff.

The way I see a possible way this project could grow is if the founders and core team (Eric, David and Bran) focus on building the platform itself, the mechanics and the infrastructure for communicating with the surface.

I think this is already a big job for them.

On top of that we (the community) can extend it to include sensors, build a fly-by-wire controller, and all fancy stuff.

Personally I'm a software developer, with a bit of knowledge of open HW and electronics, but lacking a lot in hydrodynamics and 3D printing and mechanics design. So this is also the way I'd like to work.

Simone


#7

I'm currently building my own ROV and planning on using the following sensors:

Pressure sensor - This one handles almost 300m and also have the possibility to measure the water temp

IMU - This small board have both compass, gyro and accelerometer to give all info thats needed to calculate position, speed and heading.


#8

If anybody knows sailors, ask them about nautical navigation. We could use some of the same instruments boats use to navigate or take measurements.


#9

I am planning on using the chrobotics.com UM6-LT sensor. It has 3axis digital compass, 3 axis accelerometer, and 3 axis gyro all with built-in sensor fusion using an extended Kalman filter. There are two main issues for this solution: First the digital compass being in close proximity to the motors will be a problem and therefore, I am looking to install it furthest away from the motors on the ROV. Second is the cost at about $150.

However, there are some inexpensive boards that may do the same trick for between $26 and $65. I don't know how accurate they are but you can see them on Hobbyking's website: http://www.hobbyking.com/hobbyking/store/__26588__MultiWii_PRO_Flig... for a model with GPS (to answer the question of how to locate the ROV when a tether disconnects), and http://www.hobbyking.com/hobbyking/store/__27033__MultiWii_328P_Fli... without GPS. If you don't want the compass there is a unit for $26 here: http://www.hobbyking.com/hobbyking/store/__27109__MultiWii_Lite_V1_... .


#10

Hello everybody,

I'm just entering the world of ROV (after fixed wing UAV runned on ArduPilot Mega). I'm planning to use this as IMU: https://code.google.com/p/ardu-imu/wiki/IntroductionPage

I'll keep you updated as the project evolves

Have a great day

Kind Regards

Wanderer


#11

https://www.sparkfun.com/products/7915
I found a compass modual that is comparable with the on board computer. Now unfortunately I am not very good at writing code


#12

Yes! Please keep us posted. I'm particularly interested to see how you mount it. There are a lot of possibilities, but creating a separate sensor housing that lives on the payload area seems like the best decision for the long term. Maybe short wave radio back to the main electronics housing?

Keep us posted!


#13

I believe the OSTC mk2 dive computer use this sensor:

http://www.meas-spec.com/product/t_product.aspx?id=5035

(temp and pressure)


#14

A simple (but useful) addition is a temperature sensor. They can be pretty cheap - even an old Lego Mindstorms two-wire probe could be hacked to work with the Cape.

http://www.ebay.com/sch/i.html?_sacat=0&_from=R40&rt=nc&_nkw=lego+temperature

If you plan ahead, you could even pot the probe through the e-chassis end cap.


#15

Don’t know about interfacing, but the price is right (free!)

http://www.st.com/internet/com/ordering/samples.jsp

Stmicro discovery evaluation board
http://www.st.com/internet/com/press_release/p3323.jsp