Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!asuvax!noao!arizona!tucson!bill From: bill@tucson.sie.arizona.edu (Bill Ganoe) Newsgroups: comp.robotics Subject: Re: CM Ambler Rover Summary: How small is small Message-ID: <73@tucson.sie.arizona.edu> Date: 28 Jun 90 21:25:56 GMT References: <95816@philabs.Philips.Com> <8485@jpl-devvax.JPL.NASA.GOV> Distribution: na Organization: U of Arizona SIE Dept., Tucson Lines: 64 In article , pkenny@ADS.COM (Patrick Kenny) writes: > In article <72@tucson.sie.arizona.edu> bill@tucson.sie.arizona.edu (Bill Ganoe) writes: > > . > > Certainly there are tasks that little machines can't handle, but they > >still might prove very valuable for reconnoitering the area around > >a landing site. Each mini-rover could carry one, or a few, sensor(s), > >and a swarm of "insects" can certainly provide mission robustness that > >we just couldn't afford with a big "stomper" that tried to be all > >things to all people. Conceivably, they could even be used to collect > >material for sample return missions, although individual samples would > >be smaller than a stomper might be able to handle. > > What would you consider to be a small machine? > Something 6 feet long and 3 feet high is not very small. > If it was any smaller I don't think it would be very useful, > it would have a hard time climbing over rocks and sand. > Most of the room would be taken up with drive mechanics and > computer hardware. This is if you consider it to be a stand alone > machine. > A good idea would be to use robots that act as long range > sensors for the large robot. They would attach to the underside > of the large robot, it would pick them up and store them. > They would only have to be about 2 feet long and would be in > constant contact, by radio, with the large machine. So they don't > just wander away. If the large robot saw an object with it's > camera, which would be about 12 feet in the air I presume. > It could dispatch a small droid to investigate and relay pictures > or get a sample of the object. This way the large robot could > stay on it's course without running here and there and getting into > possible danger. > I think every machine has it's place. Size is not well defined here, and I suspect that it may stay sort of flexible for a while yet. I would consider "6 feet long and 3 feet high" to be "not very small" either. Brooks has mentioned things like "3-kilogram Mars rovers", but I don't remember exact linear dimensions for the rovers that his group at MIT is currently working with. (It's definitely less than 6' x 3' though.) While something smaller might have trouble climbing over large rocks, I don't see that it should have much trouble with sand (at least relatively normal sand). The approach that Brooks is taking is to have the mini-rovers back off (or pick themselves up) and try again if they run into trouble getting over some obstacle. There might be a problem with sufficiently large solar cell arrays on very small rovers, but mini-rovers will certainly have lower power requirements than their much larger cousins. Your proposal for mini-rovers to support the mission of a larger "stomper" seems quite useful, and, perhaps, more realistic in the near term, but dependence on one (maybe a few) large rovers (and probably one launch vehicle) makes the overall mission less robust. But that is still pretty superficial. I generally agree with you that every machine has it's place. The summary to my posting said "small is beautiful -- maybe", and I noted that the issue wasn't so much big vs. little, but the perception that NASA has always seemed to go for the big "stomper" approach to space missions. -- What? Me speak for my | William H. Ganoe bill@tucson.sie.arizona.edu employer? | Systems & Industrial Engr. Dept, Univ. of Arizona | Tucson, AZ 85721; USA