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wilsonj

Need help with undgroud rover

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Hi All,

Haven't been on this forum for a few years.

My project is a little "out there".....

I have been playing around with a small tracked vehicle with a camera and LEDs for lighting, ans sending it down rabbit holes. The results have been quite suprising and very interesting.

The vehicle is currently 130mmx130mm and 80mm high. It is also completely operated by 5 metre cable and a simple tank style control box. Currently using 8 wires to control the two motors, give power and receive video. This of course has its limitations.

What I am trying to do is reduce the cables required for control. Or find much smaller cable. I don't feel wireless is an option as its quite difficult to retrieve from 5 metres down if you get stuck!

I was hoping there would be a way of controlling the two motors via 1 cable, using a PIC?

Can anyone help with this? Or offer any thoughts?

Thankyou

Regards

Jamie Wilson

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I have been planning on doing the exact same thing! I am going to use Plantraco's Desktop Rover, and my CCD camera with LED's. I am hoping to use wireless and have strong fishing line attached to the back of the rover in case I get stuck. The only thing I don't know is how deep the wireless signal will travel through the ground. I don't want to go forty feet deep or anything crazy, but do plan on exploring woodchuck homes. They don't go deeper than four feet down, I believe. Good Luck!

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I am not sure that the complexity involved is worth the effort. Especially since you would only reduce the wire count by one conductor.

BTW, how many wires are you using now and how many functions do they control? What are the currents involved?

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Hi,

Currently I have an 8 wire arrangement. I am using stripped out wire from a couple telephone extension cables, as these were particularly light wires.

I will always need two for video, but was hoping to be able to either go to onboard batteries (llipo) with one or two wire control system or try and reduce the number another way RC??

I feel that if I could halve the number of wires, that will significantly improve the performance. The other option would be to try and get smaller wires, but that creates voltage loss problems in itself.

Not sure of current draw. I have 3 LEDs, a small 12v colour camera running off seperate power wires. Then the motors, one for each track, are run off 4.8v with two rocker switches to change polarity. There is considerable loss over the wire length though.

I can post some pictures if it will help?

I had looked at the Plantraco unit early on, but decided that it didn't offer enough traction for my needs. I settled on adapting a Dick Smith kit here in Australia. I have used double modified tracks and its virtually unstopable, but a bit larger than I would have liked.

Thanks

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My recommendation is to move the battery power sources onto the tank. Your control wires should only need to carry a tiny current to activate relays (electromechanical or Solid State) or power transistors that are inside the tank. These would be used to switch the high currents used to run the motors or other power hungry accessories.

This method will eliminate any voltage drop and will also allow the use of very small control cable. It also reduces the wire count by one or two conductors (power wires no longer needed in the control cable).

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You could send a train of pulses down a pair of wires just as normal r/c gear uses. Maybe even send it via a fibre optic cable if you can find one flexible enough.

Terry

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Hi RC-CAM,

Thanks, that sounds like the simplest way of cutting (no pun intended) down on the number of wires. But I was hoping to reduce the number even further.

Terry,

Yes yes, thats the sort of thing I had in mind. I considered fibreoptic also, but I think flexibility, availability and length would be an issue.

I did have a strange idea about taking the pulses from an IR remote, and using the IR RX, and sending the siginal electrically. Any thoughts on this?

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I was pushing the hard cabled method because it is simple and reliable. However, if you want to go with a one pair connection, or plastic fiber, then look at the remote control encoders and decoders offered by Holtek: http://www.holmate.com/fae/holmate.htm

BTW, Digikey sells these.

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How far do you go down these holes ? I have made an interface for my r/c transmitter that uses the buddy box port and converts the pulse train to light and sends it down a fibre cable that I get from Maplin in the UK. I use a laser diode from a cheap keyring pointer as it gives a good strong signal, I dont know the max length of cable it will go through but I use it up to 10 metres. The only problem may be the cable as it is a bit stiff although very strong, it would not work on a very light weight machine. With a fibre cable for control and thin co-ax for the video I think you should get fantastic range.

Terry

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Great project!

I have an ROV that is homebrew, but designed for long durations (11 hours last test) in the field.

I stumbled upon the link for this site as a link on the hack-a-day site.

I might have to pull my ROV out of mothballs now!

(Google "Probe II SG" for details on my project.)

It's clunky, but it works.

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Hi Guys,

Thanks for the replies.

Currently the control wire length is just over 8 metres (20 ft)

I did consider optic control, but I feel that as stated the cable used would just be too stiff to allow proper movement through the burrows.

I'm going to try for a 2 wire control setup for now.

My aim is to get 10-15 metres down the burrows. Only possible with much lighter wire. Although I am still going to have to watch friction on corners. This will be a problem regardless of how many wires there are.

Strider, I like your rover. Although mine is significantly smaller. You have any plans on "shrinking" it?

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Hey, Wilson. Can you post pictures of your rover? And maybe a link to where I could get one? I'm in the US so I'm not sure if I could, but I'm very interested. Thanks!

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