Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!uwm.edu!lll-winken!sun-barr!newstop!sun!cyber.Eng.Sun.COM!barts From: barts@cyber.Eng.Sun.COM (Bart Smaalders) Newsgroups: comp.robotics Subject: High Accuracy manipulators (was Re: Robots in our Future?) Message-ID: <141582@sun.Eng.Sun.COM> Date: 30 Aug 90 16:52:36 GMT References: <1990Aug28.234809.15660@portia.Stanford.EDU> <1990Aug30.014817.8794@portia.Stanford.EDU> Sender: news@sun.Eng.Sun.COM Lines: 46 In-reply-to: boehlke@sunrise.stanford.edu's message of 30 Aug 90 01:48:17 GMT In article <1990Aug30.014817.8794@portia.Stanford.EDU> boehlke@sunrise.stanford.edu (Dan Boehlke) writes: I see the next breakthrough in robotics being the introduction of very high accuracy manipulators-- say an order of magnitude (or more) better than any systems of the 80's. There are plenty of potential products that simply cannot be assembled today anywhere outside of a laboratory. Very high accuracy manipulators are very difficult to design using today's technologies if they are to be of any general use. The best (gp commercial) figures I remember from the 80's are approx. .001" repeatabilty for a _light duty_ electronic assembly robot (working envelope ~ 1 cubic foot). Building a manipulator _accurate_ (not just repeatable) to .0001" with a similar envelope would probably imply: a. All major joints must be linear slides. Rotary motion is ruled out if arms are of interesting lengths, since accuracy and stiffness requirements go through the roof as arm length increases. In addition, kinematic errors due to inaccurate knowledge of zero position are difficult to reduce at these accuracy levels. b. Temperature controlled environment and workpieces is a must. Any sources of heat in the arm itself must also be cooled, or made constant in effect. A motor mounted in an arm will cause measurable deflections as the motor heats up and warms the surrounding structure. c. The tooling (end effectors, part fixturing, etc) costs will be very high. The assembly cell should be mounted on a isolated granite slab. d. Frequent recalibration and verification would be a must - this would be a rather delicate device. A interesting starting point for such a manipulator would be to look at Coordinate Measuring Machines and the technology used to build them. - Bart barts@Eng.Sun.Com -- ---------------------------------------------------------------------------------- Bart Smaalders Sun Micro Inc | This space available barts@cyber.sun.com |