I fly a mini-rover at work that uses a standard 72mhz airplane transmitter and works fine on cables up to at least 900'. I much prefer flying it to our other ROV (which has a fully "purpose designed" control system. The mini-rover is just plain quicker to respond, and that's what matters when you're flying in pipe with 12" or less visibility. Anyone doing their own control system should keep that in mind.
We've also got a long tunnel system that uses the same approach to go 3400' (different frequency and an RF amp). I'm in the process of replacing the control system with one that uses RS-485 on separate pair (the old system suffered from interference issues).
I have to admit to being seriously biased in favor of the mini-rover over any other ROV designs of it's time. It was the most elegant solution then and since everything is smaller now it has gobs of space inside for me to add cool stuff to it. It's precisely as large as you can make an ROV and still have 1 strong person launch and recover it.
A second advantage of the RC airplane controller is that you can put the video on the same coax (the mini-rover has splitter/combiner boxes, but I'm not sure they're necessary, heck, I'm not sure they're not just a shielded solder joint. On the mini-rover they wrap the standard receiver unit in aluminum tape (like you'd use on AC ducts). As far as I can tell the video from the camera goes straight on the coax, along with the control signals.
So the next question is how you take the forward/reverse and right/ left channels and mix them together to make the main thrusters do the right thing. You have a few options for this, the first is to get an RC Airplane controller that does it. The second is to buy a motor controller that does it like the one from roboteq (http:// www.roboteq.com) that does it. The third option is to code up micro- controller to do it. I chose to order the motor controller that does it, even though I have a micro-controller in the vehicle.
If you find a way to power the vehicle inside the vehicle (like with lithium polymer batteries) you can use off the shelf RG6 coax as the umbilical. The video and RF on coax is probably good for at least 1000 feet.
So basically, you don't need to program to build a usable ROV. Telemetry (depth, heading, battery state) would require programming, but if you put the On Screen Display generator board in the vehicle you can still use the single coax.
Maybe we should do an open source ROV.If anyone's in the SF Bay Area or Monterey we should get together and talk shop sometime.
mikeWho has a camera and a control system, but needs thrusters and a few other bits.
On Mar 14, 2005, at 11:27 AM, steve wrote:
Hi Emilei am also (slowly) building an ROV and did for a while try experimenting with an R/C system for control. i'm not sure if it does the control circuits any good but i found that if i disconnect the antenna's i could quite easily connect the tether cable directly to the antenna points and have control over at least 30m / 100'. like i said, its a bit 'heath robinson' and long term use in this way may be an issue but i only tried it for an experiment so dont really know. personally i have opted for a microcontroller option like Julian, albeit mine is a £25 kit from Velleman that gives me 10 digital outputs and sends the signal through a twisted pair to the receiver in the sub. specified max distance of this kit is 50m / 150' which is more than enough for my purposeshope that is of use to you steve -----Original Message-----From: owner-personal_submersibles@psubs.org [mailto:owner- personal_submersibles@psubs.org]On Behalf Of Julian FordSent: 14 March 2005 15:35 To: personal_submersibles@psubs.org Subject: Re: [PSUBS-MAILIST] membersearch--ROVs Hello, Emile.I built my own control box to control my ROV. I use a microcontroller inside to read the joysticks and switches, and then send down a serial message to the ROV.I also have written a software package that reads a Logitech wireless gamepad, and sends the appropriate signals to the ROV via an interface board I made (basically converts the serial signal from the laptop into RS-485 which can travel much further down a cable).So the answer in my situation is that custom software and/or custom electronics is required. I'm afraid that is not much help with respect to using an off-the- shelf RC controller...Let me know if I can be anymore help... Regards, Julian Ford ----- Original Message ----- From: Emile van Essen To: personal_submersibles@psubs.org Sent: Sunday, March 13, 2005 3:00 PM Subject: Re: [PSUBS-MAILIST] membersearch--ROVs Julian,The person from Finland who was on the list steered the ROV with the teatcher/pupil cable from a altered R/C transmitter. I was just curious how he did that; a simple way to get the signals in a ROV. I am not very good in electronics, jou do a good job in ROV electronics as I see.I am very interested in ROV's but have no clear question.Oops; I insulted somebody. It was not meant, I want to help newbe's as some of the list helped me some years ago. Well; if somebody is so easyly offended he is not suitable for the "silent service" thats clear.Regards, Emile ----- Original Message ----- From: Julian Ford To: personal_submersibles@psubs.org Sent: Sunday, March 13, 2005 3:25 AM Subject: Re: [PSUBS-MAILIST] membersearch--ROVs Hello, Emile. May I ask what your interest in ROVs is? I am also an ROV builder. I am currently negotiating the sale of my electronics package to "real" ROV manufacturers...this includesmicrocontrollers used to control camera pitch/yaw, and motors using PWM. It also has a several sensors, including digial compass, ROV pitch/ roll, pressure,temperature, etc. Anyway, if I can be of any help, please feel free to contact me. Regards, Julian Ford
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