An outline of the modules used in the copy demonstration, the reasons for doing robotics, and some possible directions for further work

Winston, Patrick H.

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DRAFTVISION FLASH #9WHAT'S WHATbyPatrick H. WinstonAn outline of the modules used in the copydemonstration, the reasons for doing robotics,and some possible directions for further work.DRAFTmwzkAý t \C4ýWhat has been done and whyThere exists a system occasionally capable of more orless routine copy efforts. The system is modular andincrementally expandable. We anticipate no difficulty ingeneralizing Its ability beyond the universe of brickscurrently dealt with.We feel that the generalization of specific observationsin an experimental framework Is an important mechanism forthe advancement of theory. Similarly we feel thatImplementing abstactions frequently leads us to considerimportant detail that might otherwise be passed over by astrictly theoretical approach. Consequently we have expendedgreat effort on this project because we feel the resultingsystem is a essential tool for studying the problems InherentIn big, heterarchical systems. Understanding such systemsseems central at this moment to the continued rapiddevelopment of A. I., and therefore our system, being theonly laboratory system of its kind, is of considerableImportance. Using It allows us to experiment and confirm toa degree impossible without it.What we use and whyA basic tenet of our approach Is that a minimal system,however flimsy, Is essential to the effort. With a properlydesigned, expansion oriented system, we have a tool thatgreatly promotes the achievement of our general goals, bothfrom the point of view of experimental flexibility and fromthat of good moral. Without such a minimal system our visionlaboratory would be incomplete, like a chemistry lab withouttest tubes. Our thinking would not be as sound and ourresults would not be so convincing.To get our minimal system together, we have tried to useexisting methods insofar as possible. Our idea has been torewrite the programs of Binford, Mahabala, Guzman, andWinston In such a way that the results work well together andcan support future developement. But while tangible progresshas been our goal,.this is not to say that theoreticaladvances have been suppressed. Better ideas are to beexpected from implementation efforts of this kind. Inparticular some heterarchical structure has emerged already,some flaws in previous thinking have been exposed, a numberof new programs have been written, and some new ideas of theglobal sort are developing. In particular, Freuder's papersuggests a plausible approach to developing theoreticalfoundations for much of the region amalgamation work.The modules1. The Feature Finder. <Binford>.This module performs horizontal and vertical scans.Three scan lines are in core at any given time. Theeffort is to initiate new lines and to continuealready existing lines through the narrow banddefined by the three scan lines.2. The Drawing Drawer <Horn>.Horn's program does the difficult job of transformingBinford's kruft into a decent line drawing. Lists ofrelated feature points are generated, lines areformed from them, and vertices are concocted atintersections.3. The Bookkeeper <Winston>This module creates a PLANNER data base and doesvertex identification. It resembles Mahabala'sprogram, but it goes beyond that program by way ofcomplaining about certain highly convex regions.4. The Proposer <Freuder.>Freuder distilled what we know of the Horn-Binfordprogram's skill into a line proposer. It appears tobe very conservative and rarely proposes a line thatis not there.5. The Verifiers <Lerman,Binford, Herskovits, andGriffith>Binford and Herskovits left behind a verifier inMIDAS and LISP. Lerman has nicely improved it,debugged it, and purged the LISP part. We areexperimenting with it and will have contests betweenit and Griffith's.6. The Body Finder <Freuder>.Freuder has thoroughly reworked Guzman's ideas, withinfluence from some others, into a far moresatisfying body finder. It outperforms Guzman's SEEand is superior esthetically.7. The Structure Describer <Winston>This program embodies the SUPPORTED-BY ideas ofWinston's thesis. Many of the ideas only suggestedthere are now implemented. Its results are used bythe position locater.8. The Position Locater <Winston>This small package uses support Information togetherwith calibration results from Horn's calibrationroutine to fix the position of corners. (Thisprogram exhibits some LISP code by Horn, thought tobe a rarity.)9. The Unobscured-pickupable-Brick-Finder <Freuder>This is a conservative specialist that works togetherwith the Position Locater to establish the proper armcoordinates for grasping.10. The Skeleton Extractor <Winston>SKELETON is a program that examines bricks thoroughlyto establish their dimensions in spite of visualobstructions. It Is more general but less sure-footed than Freuder's program above, but it issimilarly charged with supplying the Position Locaterwith good points. (A small routine called FLESH byFreuder interfaces the rather big SKELETON programwith the Position Locater.11. The Copy Planner <Winston>This elementary program establishes the sequence ofgrasp and ungrasp operations adequate forconfigurations lacking annoying unstablesubstructures. Peculiarly it first imagines it istaking the structure apart and then reverses theresulting plan.12. The Free Space Finder <Freuder>This supplies the Copy Planner with a location in thestorage area called HELL, at which a spare part maytemporarily reside before use in the WORLD section ofthe UNIVERSE, which of course Is the black felt-covered table.13. The SLAVE <Silver and Horn>This MIDAS code gets the AMF arm from point A topoint B. It tries to smooth out the motion Insofar aspossible and does the opening, closing, rotating,interrupting, and other chores needed to avoid chaosand danger. Silver's code handles the motion whileHorn's does the interfacing and handles the detailsof organizing the various motions.14. The Calibrator <Horn>This goes through the hair of establishing where theeye is and supplying other routines with atransformation matrix and details of the table'sposition. A pie shaped black and white object istracked in the course of this operation.What we want to doWe want to address important Issues through specific,incremental expansion and Improvement. Being modular, oursystem encourages this. Many of the possibilities to bementioned bear on more than one global question and thecategorization below is recognized as loose. We especiallywelcome criticism and suggestions on the subject of which ofthe following deserve priority and more thought.HeterarchyCertainly the study of how a big, knowledgeable systemcan work Is a major goal. To this end we have In mindchannels that carry advice, complaint, and conjecture, aswell as those traditionally thought of as data pipes. So farour system has only a few examples of heterarchy, as ourprime purpose has been to create a full system, albeit thin.Vision flashes 7 and 8 outline our past forrays Intothis area in the /reglon criticize/line proposer/lineverifier/ complex and the /object recognizer/K jointresolver/region conglomerator/ chain. All our new additionswill contribute to this study, but It is convenient here tomention the following:> FocusFixing position by Horn's focus routine nicelycomplements the known-supporting-plane method,providing a great heterarchy situation to talk aboutand experiment with.> StereoThe work of Lerman in his master's thesis raisesinteresting questions and shows that the matchingproblem can often be avoided, given objects withtexture.> IdentificationImplementation of more of the known Ideas fordetermining object identities will provide otherheterarchy hooks.Generalists and SpecialistsIt would seem that a system that can cope with the worldmust have both special and general knowledge. For example,in region conglomeration and in dimension calculation wealready have good results blending together programs thatknow about unobscured bricks with those that have moregeneral ability. To further understand the interactionpossible using both sorts of knowledge, the following may beuseful:> Wedge SpecialistsMany of our analysis modules work on more or lessarbitrary solids that are perpendicular projections ofsome two-dimensional shape. Others, like the skeletonprogram, are specialists and are so far limited tobricks. Given a skeleton program for wedges, we willhave two specialists doing the same kind of task butin different circumstances.> DegeneraciesWe want to understand bodies seen end on. In all buttrivial cases this seems to require deduction andheterarchy as well as special purpose knowledge.> ColorAn unexplored area for us, but one with potential inview of the questions color vision psycology hasraised.Theory of ScenesWorking with a real system Inevitably raises theoreticalquestions and suggests approaches to them. Eugene Freuder'sideas as outlined In Vision Flashes 4 and 5, were favorablyInfluenced by the blend of theoretical and practical factorsIn our working environment. We are anxious to stimulate moreof this and suggest a number of possiblities:> ShadowsPapert has argued for the development of a shadowtheory and Waltz has told me of some interesting ideason this subject. For example, he notes that a simplealgorithm can often establish the position of thelight source.> Texture> Objects with Curved Surfaces> Vertex FindingLerman has an exciting set of ideas about circularscan. Rather than horizontal and vertical bandswhich we now use, we would use rings of 3 or 4circular scans. A program would attempt to shrinkthese rings onto vertexes. If lines entering aparticular ring do not converge suitably on a singlepoint, more rings would be thrown off, one for eachapparent convergence point.Environmental InteractionSimon claims in The Sciences of the Artificial that muchof what appears to be high Intelligence is a happy amalgum ofsimple organism and complex environment. While the point hemakes is certainly arguable, surely the interaction ofintelligence with the environment deserves some experimentalinvestigation and we are in a unique position to do it. Ourintention is to begin with these:> Performance MonitoringThe robot should look at what it does and resolve anyanomalies between what it sees and what it thinks ithas done. Work on this is in progress.> DisassemblyThe robot should know when it Is beaten and cannotanalyze a structure completely. Then it should removethe objects causing the confusion and go on.> ExperimentIf the robot Is not sure whether something is oneobject or two abutting, It should reach out and test.RepresentationWe must worry about data base design for heterarchicalsystems working in a changing world. There are manyquestions of data consistancy and data exchange betweenmodules to be considered. We want appropriate informationavailable and we want an uncluttered memory. We wantdescriptions that themselves are part of the solutions toproblems like that of locating object storage space.MiscellaneousA number of other issues have and will emerge inaddition to those discussed above:> FindspaceThis is the problem of finding storage space for anobject.. There are reasonable methods now for testingparticular places. Susman has some nice code for thiswaiting. But we do not yet know how to find placesthat are good to test.> ConstructionA construction program can know about counterweights,glue, scaffolds, tools and subassemblies. Fahlman isalready at work on such a program.> PLANNERAs an aside, perhaps we should also note that we arethe heaviest users of micro-PLANNER, and as such wetry to contribute to the language's furtherdevelopment by way of applause, suggestion, andcomplaint.How we want to do itOrganizationIt is time to review the organization of the visionproject and perhaps redefine its purpose and scope.The responsibility of the group's various members andthe inherent limits on the group's size and budget could beclarified.The members of the group would prefer to have a hand indecision making with respect to new personnel and equipment.PeopleMany A. I. People are interested In robotics, and it isdesirable to have at least two available styles ofinvolvement. Graduate students and random, occasionallyinterested people should contribute when moved, but it Isneither fair nor desirable to rely on them for essential workas other demands on their time take preference. In anothergroup, the sort of core robotics group, one should haveindividuals who can thrive in results mode, the atmospherebeing like that maintained in the vision group in the recentpast.We speculate that graduate students will produce newideas on the more global, abstract, unexplored questions withwhich our laboratory has negligeable experience. Paidshorter-term undergraduates, should concentrate on theseemihgly straightforward Implementations, which generallyprove tb unleash plenty of problems to be of educational andtheoretical benefit. Salaried graduate students and staffare in an ideal position to both abstract theory from resultsand realize theory as results. Consequently they should mixtheir efforts so that they not only keep close to the systemand improve it, but also bring their experience to bear onthe deeper theoretical issues that emerge and becomedifficult long term Problems.The core group needs Freuder, Lerman, Griffith, Winston,and a Horh substitute. The Intention Is to wait patientlyand be very selective in attempting to fill vacant slots.Any person should at least potentially be available forbeyond one year's time. We would like to have two or moresummer student-type employees if suitable candidates appearby way of work in 6.258 or 6.544 term papers. The extrasupervision time available in the summer permits good use ofsuch people.

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