railgun bore inspection robot

soyyam

I'm new to robotics (I've never built one from scratch).·


Well, the robot I need to build needs to fit into a 38 x 38mm bore, but then also stay centered in a 76 x 38mm bore.· The robot needs a camera (I think I've found one here: http://www.supercircuits.com/index.asp?PageAction=VIEWPROD&ProdID=4013), about 8 LEDs that should either be able to dim and brighten or just have a couple turn on and off.· Distance detection is also important, I've thought about sonar and the other option that's come up is a digital tape measure.··(Distance from the end of the bore, the·longest bore is 7 meters).· For centering I've thought about whiskers, but that would require steering and the people that I'm working with want to keep it so the robot only moves forward and back.· So, my lab partner wants to put wheels on the side that spring out, or something to that effect.· Currently, I'm in charge of buying motors and gears (I never was good at mechanical physics) since my lab partner's out of town for the week.· Basically, I'm just looking for ideas on how to possibly implement some of this and where to find parts that are small enough to fit into the bore.

Thanks

Post Edited (soyyam) : 6/9/2005 5:18:58 PM GMT

jdolecki

Where else would buy small parts at, but

http://www.smallparts.com/

Paul Baker

Ok I just wasted·a half hour looking for something I remember playing with when I was young but seems to be superceeded by a different product. It was a dry wall anchor that looked similar to·this dry wall anchor, only there were two expansion bars instead of 4 and they had pivots which permitted expansion·and contraction of the assembly. The collar near the screw head has no threads, so that tightening the screw draws the threaded right collar toward the screw head causing the wings to expand. If you were to derive an assembly that operated off this principle and placed rollers at the expansion joint, your bot would be centered since expansion is equivalent in both directions. Using springs can result in the bot not being precicly center, especially if there is any variation in the stiffness of the springs.

At the scale you are talking about, using a laser distance measure will provide the highest accuracy.

allanlane5

For those of us who are 'metrically challenged', a 38 mm bore is 1.496" in diameter -- smaller than an HO train, I think. In a 'snake' configuration (all parts lined up in a row) a BS2 would fit, with a long 'tail' of 4 AA batteries strung end-to-end. A 9-volt battery would fit as well.

They do make cameras this small. Now, motors: If there are servo motors this small, do they have enough power to be useful? Servo motors would be the easiest to interface with the BS2.

I wonder if a 'tethered' mode would be possible -- have a BS2 with some motors on a 'platform' with the camera, drag a 'tail' wire which would supply power, and return video signals to a 'parent' PC.

www.kronosrobotics.com

Built a 'rover' for inside heating ducts -- but it was much larger, I believe. Still some of his techniques might be helpful.

Post Edited (allanlane5) : 6/10/2005 4:24:11 PM GMT

Orion

Look at toggle bolts

http://www.allproducts.com/search/products/pM01030431.shtml
http://www.usahardware.com/inet/shop/item/40940/icn/20-031328/midwest_fastener/4086.htm

allanlane5

If you are really brainstorming here, an 'N' scale model train, pushing a flatcar with a camera and battery on it, might suit. Or you could purchase an 'N' scale engine, replace the wheels with some rubber wheel equivalent, and use that. Just a thought.