Position System like GPS but localized

[JonB]

Originally posted by: johnpombrio
If you could, just paint the damn things a different color.
If the robot can just go in, have it carry a spray can and a solinoid to trigger the spray can.
Stick a magic marker or a sponge full of paint on the end of a stick and run it into a pipe to create a dot pattern.
If the pipes are hot, stick a marble with a high temp slow set epoxy onto the end of a stick. Stick it to the pipe. Use different colored marbles or different number of marbles.
Stick a kids sticker of a different flower shape on each of the pipes or on the sphere near the pipe.
Create vertical stripes on the ground with paint in various patterns.

No paint, no stickers, no epoxy - all of those are potential sources of chemical contamination that will promote chloride stress cracking at high temperatures and pressures. These are nuclear reactor parts - cracks are "bad."

degibson, I'll look into a sonar approach. They put those little sensors on so many car bumpers now, they must be cheap and reliable. I don't think the radiation field is strong enough to keep them from working reliably. Even so, they could change out the sensors for next to nothing.

and - this robot has no processors - it is controlled solely by a remote joystick, driven by someone watching video from onboard cameras. The composite video umbilical cables it pulls is one of the biggest drawbacks it has.

 

[JonB]

As I look at the sonar rangefinder link, I began to picture it more as a Radar map. If the Sonar rangefinder was on a vertical shaft and rotating at a known rate, the software could build an on screen map of obstacles, just like weather radar or fighter plane radar.

 

[degibson]

The rotating-sensor solution requires moving parts, of course... I tend to avoid those in my little projects because they break first. I do not doubt, however, that it would 1) work and 2) be quite cool.

 

[jagec]

Originally posted by: TuxDave
I've seen a Panera Bread wired up like that using some sonar based locationing so that the waiters can find where you sit faster. They stuck it in the coaster that you take that has a number when you order.

I was about to say that given the small scale of the place, sonic or ultrasonic-based ranging or positioning might be the way to go.

If you can't put the sonar unit in the robot itself, you could build a triangulation system similar to the GPS system with 4+ transmitters in different parts of the interior, and a computational routine in the robot that uses this info to calculate position.

Side note: about a week ago I learned that fixed-position GPS stations get down to MILLIMETER accuracy once they publish corrected satellite positions (~2 week lag time IIRC). That kind of precision on that kind of scale astonishes me.

 

[degibson]

Honestly, I'm worried about offloading any computation to the robot, because of the radiation. Soft errors are really scary -- they could cause a crash, they could cause a wrong position to be computed. Given that this little guy is going into a PWNR, I assume the consequences of a false position are high.

Honestly, I don't know enough about lingering radiation to know if it will be a problem or not. I do know that decay from random alpha particles in semiconductor packaging can yield soft errors ... and thats not in a radioactive environment.

 

[daddyo]

Funny, I know this inspection because I used to be an engineer at one of the firms that designs the robotic crawlers.

Our solution was for the operator to be very careful, but this was several years ago, so the tech wasn't necessarily there. It was a very tough inspection.

I think the INS solution has the best shot at working. Run a row, reset sensor, run a row, reset sensor.

Everything else with a transmitted signal is probably a no go.

 

[JonB]

Thanks. I've sent the recommendation about INS to the designers/owners of the equipment. Haven't heard anything yet. While I personally like the idea of a sonar sweep display, I'm not sure it would be as good.