Spektrum DX5e 2.4ghz / .10 Brushless motors / 30amp ESC/BEC

[ROVALTON]

Morning folks,

My father and I are working on an ROV for the specific purpose of surveying work sites no deeper than 100 feet. well... he's building it for that, I'm just obsessed with building one. He's got a long history as an Electrician, and I'm the Systems Adminisrator for an IT company. Together we've come up with something that I've been trying to find here on the forums, but have yet to see.

I'm a huge fan of K.I.S.S. so here's my design so far:

Top side:
Spektrum DX5e 5 channel 2.5ghz controller (one channel is on/off)
AR600 receiver (Spektrum)

ROV side:
4 x 11.4v 1300mah LiPo batteries
4 x Rimfire 1350kv Brushless motors w/ 40mm brass prop
4 x 30amp ESC w/ BEC (forward/reverse)
1x Panasonic BL-C111a IP Camera (wired)

ROV itself:
This is being built out of Acrylic and PVC mainly. I'm using Acrylic vacuum molding to limit the amount of water displacement so I can keep the ROV small... but not to small. Rough estimates on size... I'd say 12"x12"x8 (WxLxH)

Now I've done testing, and everything seems to work... but we all know, test environments leave out the little things. Once I get the frame build I'm sure there will be lots of tweaking. This is, afterall, our first ROV.

This design allows me to run 2x Cat5 runs to the surface, and that's it. 16x24gauge wires. 3 for each motor control, 4 for the IP camera.

If anyone has anything they can suggest, or problems they might see with this design, please speak up now... I'd hate to go any further only to find out something isn't going to work



-ROVALTON

[bikerbones1968]

Looking at your video, and If I understand your concept, your going to leave the receiver topside and send your signals on cat5 to the ESC's below? That will work but on a lot of extra wires. By using just the PPM data stream and sending it to a receiver onboard everything is controlled over a single twisted pair. Smaller tether = less weight and less drag.

There are two idea's for you to look at.

Option 1 - tether must be connected via the trainer plug ( if your radio has one ) or DSC ( Direct Servo Control ) and use the PPM data to drive a receiver that is DSC capable onboard. Option 2 - Use a coax to extend the TX signal down to the ROV. Never tried Option 2 personally. If you search the forums for RC control you will find all the information on how it's been done.

[bikerbones1968]

Here is some good info. viewtopic.php?f=15&t=370

[ROVALTON]

Definitly a good read! Thanks for the info Biker!

From what I'm understanding, this would drop my tether from two Cat5 (8pairs) to one cat5 (4 pairs).

I also don't think my DX5e has a DSC port, I'll need to check that.

I've also decided not to go with Acrylic vacuum molding, supplied are limited where I live, and finding the proper acrylic and welding agent has proved very difficult.

[bikerbones1968]

You are correct. On a single CAT5e you can send your control data down to the ROV on one pair, your video feed to the surface on another pair. The remaining conductors could be used to feed audio to the surface to monitor a leak sensor on board or sensor data etc..

A lot of the older computer radios that operated on 72MhZ came equiped with a DSC port on the Tx and the receivers were designed to link with a DSC connection. DSC was incorporated to eliminate possible interference with other fliers on the field if you were testing your servos, flaps, throtle and other controls on the ground. It actually by passes the RF portion of the radio completely. All the newer 2.4GhZ radios today do not cause interference to other operators so most do not have a "DSC port".

On another thread we got way off topic but if you read through the thread there is a little more detail on DSC setup.

viewtopic.php?f=13&p=3656#p3656

[ROVALTON]

I've been reading thread upon thread... lots of great info here, that's for sure! (sorry, keyboard is almost dead...)

One of the hurdles I'm forcing myself to live with here is the 2 pair cat5 for the video feed. I'm using an IP Camera so I can feed the video to a 10/100 wireless router at the surface. this allows clients and myself to all watch simultaniously via smart phones, big screen.. whatever is available.

I'm mounting my Transformer tablet on top of my DX5e so I can literally sit anywhere within 100 meters of the 2.4ghz receiver top side and control the ROV.

I do have a new question you may be able to answer... I've been researching waterproof RJ45 connections, the best I can come up with so far for the price and availability are the Laird ones.
http://www.balticnetworks.com/rj45-ethe ... tdoor.html

I know these are not waterproof, but I'm thinking if I harden the wire housing from inside, say... fiberglass resin, and add some sealant, do you think these would be fine down to 100 feet?

-ROVALTON

[KR2_Diving]

Hello,
I dont know what kind of budget you have in mind, but the plugs in the link below might be what you are looking for.

http://bulgin.co.uk/Products/Buccaneer/ ... ernet.html

I cant remember where I heard of these, but I know it was on this forum somewhere...

Looks to be about 40 GBP ($65) for this set up. It is IP68, and you would still have to modify the cable entry slightly... but it could be an option never the less. They seem to be readily available here in Europe.

Ryan "KR2_Diving"

[ROVALTON]

those were the original ones I was looking at... they would have been my choice for sure, but they come prefitted with specific lengths of Cat5... if the rip the existing cat5 out, and slap your own in there, I'm not sure how well it would work.

[ngkb]

Hey, guys. I have a question, how did you programme the flight controller to make the motors move. Say if I want my ROV to turn left, how do i send the PPM signals to tell the the right motor to move at constant and the left motor to slow down or stop?

Another question would be, how are you going to connect the cat5e cable to the receiver? I have 3 ESCs as I have 3 motors and requires a NTSC cable for my livefeed camera. Is 1 cat5e wire enough or ?
PS: I am new to building a ROV.

Guys, do help! Thanks!

[bikerbones1968]

Cat 5 is more than enough for conductor to drive a PPM signal to the receiver on the ROV. To get the stick inputs on your radio to do what you want for motor control its all in the radio programming menus.

For example in my JR XP6102 72MHZ FM TX using DSC this was the basic programming parameters.

I will explain it best I can. I went into the Mix menu and for MX1 selected AIL to ELE. I set AIL to -100% ELE to -100% SW was set to ALWAYS ON

Then in the mix menu for MX2 I selected ELE to AIL and set ELE +100% and AIL +100% SW was set to ALWAYS ON.

With these settings the AIL channel mimics the ELE channel so pushing the stick up, both motors will run forward, pushing the stick down both motors run in reverse.

Now MX2 being programmed exactly opposite in settings as MX1 when pushing right on the stick the left motor runs forward and right motor in reverse turning the ROV right. Stick to the left makes the right motor run forward and the left motor run in reverse turning the ROV to the left.

Another cool thing when going in a forward direction and for some reason i.e. water current is present and I am drifting to the left or right, I can feather the control either right or left slightly to apply more speed to one or the other thrusters compensating for drifting. When reversing the controls it also allow you to feather left or right with the same results. Each stick movment on any of four diagonal positions operate the motors independantly either forward or reverse.