dietz@SLB-DOLL.CSNET (Paul Dietz) (02/08/86)
>> Because it's hard to keep people in GEO. Teleoperator technology would >>extend easily, perhaps all the way to the moon. >As far as I can see, the only difference is in delta-vee, and robots and >teleoperators pay the same that people do. The difference is people have to be supplied with shielding, food, water, air, and have to be brought back after a while (so the delta-V isn't the same). >Granted you don't want to do much construction at 100 nm, it doesn't follow >that you want to do all or most in GEO. HEO, 200-1000 nm up, might well be >preferable. I'll buy that for things built from earth-launched materials. At what altitude will the space station be? >"I don't believe...". This argument is really about marginal cost, and neither >you nor I have the figures. The teleoperator/robot people have an advantage; >they have fixed NASA manned costs to shoot at. Paul, I will happily buy your >argument, if you can tell me, with firm numbers, what the >teleoperator-constructed Space Station will cost. Until then, you're >betting on the efficiency of an untried technology, a bet few of us would >care to make without more information. Yet we are willing to build the space station on very vague arguments for its utility. There's a double standard here. I'm really arguing plausibility. Human EVA in low orbit is very expensive: I estimate very roughly around $100,000/man-hour of useful work when and if a space station is built (I'd like to the see the NASA number). A $10 million teleoperator system will pay for itself in well under a year, even if it is ten times less efficient than a man in a space suit. Away from the station an advantage would be even greater. Let's take a crack at estimating the cost. A teleoperator on a space station will have (say): two direct drive robot arms with replacable end effectors, a carousel device for holding the effectors, several CCD TV cameras, a communications system (fiber optic or microwave), a control computer, a power supply (fuel cells, batteries or direct wiring to the station), and a frame to hold it all together and hold spare parts. Also, it would need a ground interface: computers, input devices, video and graphics displays. I see no reason why such a device couldn't be built for more than a few hundred thousand dollars (ignoring development costs). Even if space qualification multiplies that by ten it should still make sense for EVA in low orbit. Development costs are harder to estimate. To get a firm estimate of costs we need to know what the space station will be used for (one can't, after all, predict how much a factory will cost if you don't know what it's making). Given what we know about products that can be economically made in a space station, I'd say extremely inexpensive teleoperators could make them just as well as humans. >No one thinks that such machines are impossible in any physical sense. I think >that they're probably beyond current ME and CS technology. I could be wrong. >But I don't think increased demand is going to solve the problem for you; >mechanical linkages really don't have terrific economies of scale. You misunderstand. I wasn't arguing that economies of scale will make teleoperators cheap; rather, I was arguing that they hadn't been developed because it hadn't been worth anyone's while to do so for terrestrial applications. Also, I'm not arguing for extremely capable teleoperators that can fully replace humans with no loss of efficiency; rather, I want remote-controlled dumb manipulators that may not even have tactile feedback (although I'm willing to take any additional functionality that's feasible).
eugene@ames.UUCP (Eugene Miya) (02/16/86)
Paul Deitz writes: > I see no reason why such a device > couldn't be built for more than a few hundred thousand dollars (ignoring > development costs). Even if space qualification multiplies that > by ten it should still make sense for EVA in low orbit. > Development costs are harder to estimate. Well, is that is the case, why don't you form a company and build such a device? If Fortune Systems could get $110M, I'm certain you can easily raise $1M. I personally think your estimates are off by one order of magnitude, but don't let me stop you. I left the "Development costs" in there as your floater. If you build something decent, I'll point you to the door in NASA to sell such a device. I just want to do for you what Seymour Cray does for every person who comes to him with an idea to improve one of his machines: Go do it. From the Rock of Ages Home for Retired Hackers: --eugene miya NASA Ames Research Center {hplabs,ihnp4,dual,hao,decwrl,allegra}!ames!aurora!eugene eugene@ames-nas.ARPA
dave@quest.UUCP (David Messer) (02/19/86)
> You misunderstand. I wasn't arguing that economies of scale will make > teleoperators cheap; rather, I was arguing that they hadn't been > developed because it hadn't been worth anyone's while to do so > for terrestrial applications. Also, I'm not arguing for extremely > capable teleoperators that can fully replace humans with no loss > of efficiency; rather, I want remote-controlled dumb manipulators > that may not even have tactile feedback (although I'm willing to > take any additional functionality that's feasible). Teleoperators HAVE been developed for terestrial applications -- they are in use in various undersea operations. So far their capability is fairly limited although I suspect it will improve fairly rapidly over the next decade. They cost about $100,000 to $1,000,000 per unit, so I suspect it would be more like $50,000,000 for one to use in space. I think the development costs would be extreamly high however as there isn't nearly as much data on the problems of working in space as underwater; there had been hundreds of years of manned exploration of the sea before robot submersables became possible. -- David Messer UUCP: ...ihnp4!quest!dave ...ihnp4!encore!vaxine!spark!14!415!sysop FIDO: 14/415 (SYSOP)
dietz@SLB-DOLL.CSNET (Paul Dietz) (03/01/86)
It's clear from the pounding I've received that I'm being too optimistic on teleoperators. Mea culpa. The Oberg's have just written a book (whose titles escapes me) that has a chapter on space robotics and teleoperators. I don't recall all it said, but one interesting point was this: if the cost of man-hour of work in space is around $35K it makes no sense to automate a task that will be performed fewer than about 1000 times, because development cost swamps operating cost. They also quoted a report on teleoperators and robotics that said manned presence in GEO is very difficult due to shielding requirements (you would need a "submarine made of lead" according to one expert). [GEO must be in the fringes of the radiation belts?] I'm not sure I believe that 1000 times figure, but development costs are nonnegligible, especially for special purpose devices (like space station assemblers, for example). One difficulty they described with teleoperators is the operator remains in normal gravity, making it hard to overcome up/down orientation biases. Astronauts in zero gee apparently quickly adapt to the lack of a preferred orientation.
dietz@SLB-DOLL.CSNET (Paul Dietz) (03/06/86)
Aviation Week (March 3, 1986, pages 73) has an article on Canadian plans to upgrade their manipulator arm for use on the space station. According to the article, about $300 to $600 million in funding is required. The Integrated Service and Test Facility would be a shelter with a removable cover and a seven degree of freedom manipulator arm 50 - 60 feet long (three d.o.f. at the wrist, one at the elbow and three at the shoulder). A smaller robot about 20 feet long could be picked up by the larger arm. The small robot would have two arms, a coarse are with 7 d.o.f. and a fine control arm with 8 d.o.f. The large manipulator arm would not suffer from some of the control singularities of the current shuttle arm, and would be able to manipulate up to 200,000 pounds of payload (the mass of a shuttle orbiter). The shuttle arm must be lightweight and waves around when carrying heavy payloads. The Canadians want their facility to be able to undo bolts and screws and ultimately be able to remove boxes and circuit cards. According to James A. Middleton of Spar Aerospace, Ltd. this depends on designing spacecraft interfaces to make the task as simple as possible, with units mounted in the spacecraft with snap fasteners or something similar. So, it looks like teleoperators could be feasible, but will initially be part of a space station. I should have realized the space station would provide a good environment for field testing space robotics. John Redford writes: "If we want to do things farther away than our low-orbit backyard, we'll have to put people there." If speed-of-light delays are crippling humans will be needed in GEO and beyond, but they'll be advised to use remote manipulators for radiation protection. If the space station gets built it probably won't be hard to try experiments controlling the arm(s) from the ground via the TDRS satellites.