Remote operated vehicle

Hi All

I am developing a remote operated vehicle for a customer, its a tunnel inspection machine so wireless is out of the question. The standard systems seem to be limited to 500m of cable because of transmitting the video signal, my customer has asked for 1km with an option of going to 2km. I thought I would make eveything on the machine communicate using ethernet and replace the multistrand copper standard cable with two core optic fibre (plus a few spares). Then I can use a standard IP camera with built in pan and tilt, the controls can be operated using OPC servers on the machine and an OPC client on a controlling PC. I realise the fibre may be a weak point but I have a fall back position of ethernet to dsl converters over copper.

What do you think, work like a dream, or tears before bedtime?

Bryan

I'm no expert in this area, but my 1st impression given the distance would be to dive into the books on fiber optics. But I think you biggest problem with a cable connection is going to be with the mechanics of cable delivery and takeup between the operator and the remote unit. How do you handle 2000 meters of cable? Do you unwind it at the entry and try to drag it out with the remote? Or is the remote going to be large enough to carry the entire cable and play it out and take it up on the remote? Either way, what if it gets tangled?

Ok so given the cable problems, maybe you want to take another look at a wireless solution. What's the actual tunnel configuration? Is it a streight 2KM shot? Does the tunnel twist & turn? How large dia is the tunnel? What is the wall lining, (Steel pipe, concrete etc)? Are there other access points? Can your remote drop off two or three repeaters along the path?

1) What's the factor(s) that eliminates wireless off the bat?

Even if you have to have a repeater, wireless still offers enormous benefits over reeling out and reeling in fiber or cable. If your access point were in the middle of the tunnel, you halve the max distance to the vehicle.

If I understand what the sales guy told me, some industrial ethernet radios now have two antennas, which can auto switch between each other; I'm thinking two antennas: on the access poitn: directional to the right and directional to the left. On the vehicle, directional forward, directional to the rear.

2) OPC ? The OPC I've done is, by comparison to video, small amounts of industrial data. 300-400 points of industrial data is only a couple scan lines of video data. Have you tried video over OPC? I don't know whether it works or not, just asking.

Dan

I would contact Data-Linc and run it by them. I would try the wireless solution. With directional antennas, I think the results would surprise you. Data-linc.com They are good about letting you use their equipment for 30 day trials.

Hi All

Thanks for the thoughts so far.

What's the actual tunnel configuration? Is it a streight 2KM shot? Does the tunnel twist & turn? How large dia is the tunnel? What is the wall lining, (Steel pipe, concrete etc)? Are there other access points? Can your remote drop off two or three repeaters along the path?

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The tunnel twists and turns with a diameter down to 18 inch and the walls are generaaly rock or concrete. With the small tunnels I would limit them to 1km and do a mixture of dragging the cable to begin with and laying after that. Because Fibre cable is faily small diameter (8mm) I can get away with a 0.5M cable reel on the machine. If the cable gets tangled then there is some expensive digging to do, anyone got a big shovel? Having said that the savings from being able to 2km runs is considerable, the only time a tangle could be a major headache is if the failure happens under a river or other obstacle.

1) What's the factor(s) that eliminates wireless off the bat?

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Wet gound, on another job I tried getting a signal from just 1 meter below ground and got nothing, big aerials, amplifiers, repeaters, nothing worked. Water is nearly as good as steel for stopping wireless.

2) OPC ? The OPC I've done is, by comparison to video, small amounts of industrial data. 300-400 points of industrial data is only a couple scan lines of video data. Have you tried video over OPC? I don't know whether it works or not, just asking.

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Sorry, I didn't describe that bit well enough, the OPC is just for machine and camera control (pan/tilt). The Camera would be one like Axis make, it transmits over standard ethernet.

DANW - The OPC is one of my concerns, from your experince is it up to running an ROV, do the instructions get through quickly?

Bryan

I would contact Hirschmann and opt for the bat wireless system. It is a little bit more expensive than conventional stuff but i use it on two shuttle cars moving across a factory floor in a linear fixed motion. The setup is automatic and the quality of the product is excellent. You will need to contact your local routeco rep. I dealt both with routeco and Adam Pryke of Hirschmann and they will also commission the system free of charge.

Alternatively this guy is a diamond and will help you immensely, let him know Ryan from Rockware has passed his details on if you contact him. www.netdot3.co.uk his name is john french (a network specialist) and this is his company.

Just a thought

Is this running off batteries or do you have to drag a power cord? You could look at a power line type network. Just put a filter on each end and send data along with the power.

http://www.powerlinecommunications.net/index.html

BryanG said:

Wet gound, on another job I tried getting a signal from just 1 meter below ground and got nothing, big aerials, amplifiers, repeaters, nothing worked. Water is nearly as good as steel for stopping wireless.

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Water is known to kill 2.4Ghz really well, and 900 MHz is negatively affected. I understand your reluctance.

BryanG said:

DANW - The OPC is one of my concerns, from your experince is it up to running an ROV, do the instructions get through quickly?

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My experience has been SCADA/DAQ with 1 second updates. Fast throughput was not an expectation. I really don't have the experience to give you a yes or no.

Dan

Could the robot drop repeaters on its way in and and collect them on its way back? Or maybe a couple of small repeater robots to follow along and stop as needed?


Just a thought

Marc

Hi All

ChalresM - The existing units drag the power cord but it causes me two problems, the weight of the cable and the voltdrop over 2km. In an ideal world I would use Fuel Cells instead of batteries but fuel cells aren't good enough yet. I like the powerline system I use Homeplug at home, if only they would get X10 working over Homeplug everything would have an IP address and everything would be automated.

Marc - Love the idea of lots of little bots. I originally wondered about making the inspection system fully automatic but then I saw a programme on TV, the 'Great Challenge', or some name like that, where they had to make robotic vehicles navigate themselves across the desert. The number of sensor and processing power made me think again. Though I don't have to deal with cliffs and going off road, I do have to deal with side tunnels, rockfalls and flooding.

Another concern in the system is that the operator will be staring at the screen for over a hour. I can manage about 10 mins before I get a dots in front of the eyes, 'Tunnel Vision'. So another question is can I train a machine vision system to spot cracks and faults in the walls?

Thanks

Bryan

Bryan,

What are the tunnels used for?

Mike

You know I'm not going to answer that question. There is some money to be made from this job and others on the same project and other projects around the world and I want it to be me that makes the money?


Regards

Bryan

Bryan,

I was just trying to figure out if it was a utility tunnel (with cables & wires etc.), or water/sewage. 18" dia x 2km with no intermeideate accesses seems pretty unusual. The web abounds with ROVs for tunnel inspection. It appears the most of the long range ROVs use teathers. But the smaller the tunnel dia, the less range the ROV has to spool out & in the teather, simply because the ROV needs the power& space to carey & or drag the teather. It seems that your ROV might require two spools, one on the ROV & one at the entry point. When the ROV gets out so far that it cant pull the weight of cable from the spool at the entry point, to further extend it's range the ROV would then play out the spool on the ROV. Either way I would say that you need to go with a theather, and if theres a failure the theather could be used to retreave the ROV.

I was thinking along the same line a few years back:
An ROV to do exploration of caves. The idea being to have a laser range finder that recorded Alt/Az at various points on it's travel.

A multi strand coax and use VLF radio. VLF will penetrate earth up to a point.

I don't have the data now.

Rod (old tail-gate caver)

Kalatel company makes a video camera controler P T Z using 1 twisted pair The root of the system is missing pulse