Lost the wings/fins but got ears


#1

I decided to move the motors to the outside of the OpenROV 241 this week. So I removed the wing/fins I printed last week and drew up some motor housings in Autodesk Inventor and printed 2 of them on Wed. night, this took 21 hours on my old 3D printer. On Sat. I attached them and moved the motors and props. This morning I went down to the lake for a test spin.

I have a lot more drag now (read that as much slower) but I am able to control the unit better. It almost drives in a straight line and my diving going forward is gone. I need to do more testing. Now that I have them made and attached I can see things that could be improved. They need to be a little longer and the sides that attach to ROV metal housing could be full of holes to make them lighter. Do you think adding a funnel shape to the output side of the props would give me more thrust or be worth while? It would be easy to draw funnels, 3D print and then attach them.

I am still running Brian's code for the gyro, which is really great. You can watch the compass turn as the unit turns. I moved the electronics for the gyro to the tube you see on the top of the ROV. Now I can tell if I get water in it. The plastic box I used last week was big and leaked. I like the tube much better.

It was a great day to go to the lake and everything worked.

1227-OpenROV_Dev_Horizontal_Motor_Mountv2dwg.pdf (176 KB) 1229-openrovinwater.jpg (214 KB)

#2

John,

Thanks for this great post!

Could you share the stl version of your file? I'd be glad to test the ears!

btw, I noticed the go pro holder... Where did you get it? Could you share the stl file as well?

Kind regards,

Benoit


#3

I have attached the motor housing stl file. I think it could be improved before printing more. It should be a little longer. My props are flush with the edge. I can make changes to the cad file if we can come up with a better idea?. Maybe it should have holes in the housing so you could add nozzles on the output side? Or a adjustable flap to direct the output?

The other 2 things I have 3D printed and on the OpenROV are the battery tube holders and the GoPro camera mount. Both of these can be found on thingiverse.com web site. The battery tube holders are very useful because they make it easy to remove the batteries when you disassemble the unit.

1239-openrovfrontwithears.jpg (193 KB) 1240-3dprintingmrtmount1.jpg (118 KB)

#4

John,

Thanks a lot for sharing the ears. I am eager to receive my mendel max to print them! :)

In the mean time I'll use our fablab and I'll keep you posted.

What kind of filament are you using?

Don't you have issues with water?

Regarding the batteries holder, I am using regular plumbing holder we can find in shops here:

http://openrov.com/forum/topics/battery-holders

I'll check on thingverse.com.

Kind regards,

Benoit


#5

Hi John,

Great post, really interesting read.

Would it be possible to send me some information on the heading/gyro/compass system?

All the best,

Phil


#6

I am using Brian Adams code which supports Pololu Minimuv-9 v2 gyro, accelerator and compass.

I have included a couple of screen shots. notice the gryo compass across the bottom of the USB camera picture. On the right you can scroll the data window and you can see roll, pitch, yaw, my depth and my W-temperature. I turned the OpenROV on each picture so you get an idea of what it looks like. I mounted the little board in an orange tube on top of the OpenROV and ran 4 wires up to it (power, ground, clock, and data or the I2C bus). I have a metal frame and it did not work in the electronics tube.

John

1235-OpenCockpitp1.JPG (251 KB) 1236-openrovsetup.jpg (190 KB) 1237-OpenCockpitp2.JPG (243 KB)

#7

I am using Stratasys P400 ABS model FDM part number 300-20000 filament.

The part is solid (not worried about leaking) and other discussions in this form have talked about 3D printed items absorbing water and ways to fix them. All I did was print and paint it. Today I made changes to the motor mount to make it lighter and a little longer. See attached.

John

1233-OpenROV_Dev_Horizontal_Motor_Mountv3b.pdf (139 KB) 1234-OpenROV_Dev_Horizontal_Motor_Mountv3a.pdf (119 KB)

#8

Love the Cockpit and very anxious to get this in my ROV as soon as they become available. Does the current Image have this already coded in or did you have to add the code to the BB, same for the Arduino? I also noticed you put the motors on the side, did this give a better backward thrust. I am considering changing my motors for the same ones used in the OpenROV to reduce the current on the ESC's, mine currently are 22amp motors and the esc's are only 18amp but I am uncertain if smaller motor will provide enough thrust. I am also thinking about getting the 25amp esc's as I have one that looks like it has an issue on the reverse thinking that the higher current motor that I am using may have damaged it.


#9

You need to update both the BB firmware and the cape firmware. You can buy the gyro board from Pololu, that is what I did. It is easy to wire up. see attached. I all so added some code to the cape board for my pressure sensor and temperature sensor.

I don't know about backward thrust but it did help with diving going forward and surfacing going backward.

John

1230-gyrobarebd.jpg (170 KB) 1231-gyrobdintube.jpg (123 KB)

#10

Hi,

thanks for sharing it. I guess there is an issue with the unit since the viewer shows me a 8mm item...

What is your base unit? Could you export it in mm?

Regards,

Benoit


#11

I got the same Pololu sensor but for some reason I'm having issues with the Arduino code that supports it (https://github.com/OpenROV/openrov-software/issues/133). Are you running the latest version with just the module enabled in the settings (HAS_POLOLU_MINIMUV)?

Also how did you wire the sensor to the cape?

Thank you!


#12

Hi John,

I've found the gyro board from Pololu, the wiring for it looks straight forward. How have you mounted the gyro board, in a separate waterproof casing?

In terms, of the arduino code provide by Brian Adams, is this added to the OPENROV image file that's uploaded onto the SD card?

Phil


#13

I had a tube laying around and I glued it to a little board to fit in the tube. Where I poked the holes in the end cap for the 4 wires I used epoxy to seal it.

You can still pull the end out with the board.

You need to use the latest code. I am now using the latest image which makes it a lot easier. So yes you need to update the SD card and the cape firmware.

For wiring I pulled ground and 5 volts off the cape on J1. For the clock and data for the I2C bus I used the connector at P4. Pin 1 is the clock (scl) and Pin 2 is data (sda).

In the cape firmware I enabled just the MINIMUV changing the 0 to a 1,

#define HAS_POLOLU_MINIMUV (1)

in the setting.H module.


#14

Magic!

Thanks John :)


#15

Can you please let me know if you manage to get the cape code working? I'm having trouble running it.


#16

Mine works and I have done several dives with it. I have sent in a couple of videos that show it working but they did not post them. As I said above the latest image released works. You need to enable Minimuv, compile the code, and then send the new file to the cape board. The only problem I had, was at first I mounted it in the electronics tube and the reading didn't change. On my bench all apart it worked. So I mounted the sensor on top on the OpenROV and it worked. Hope you figure out your problem.


#17

Thank you John! I've managed to get it to work, I was having a wiring issue and the details you've provided helped a lot.


#18

John,

Thanks again for sharing the design. See how I could re-use it to build OpenDyP v0.1

Regards,

Benoit