eight ultimate challenges of human-robot communication

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EIGHT ULTIMATE CHALLENGESF HUMAN-ROBOT COMMUNICATIONThomas B. SheridanMassachusetts Institute of Technology, Cambridge, MA 02139,USA

The invitationcommunicatiorby authors. ItIn that spirit Iterm problemsincludingthe high-levelSince t lserious consideration,prosthetic armsof telemanipulahas changeslanguages ofsame is true formore preciselyIt isthemselvesoperator and themore and moreSo herecommunication.1. Extendinq

to give this keynote came with a suggestion that human-robot, he original theme of this conference, was in many cases being abandonedwas also suggested that there should be effort made to return to that theme.nave contemplated what I believe to be eight of the most challenging long-in human-robot communication. I interpret this phrase in a broad sense,comrnunication among the designers of robot systems (namely us) with respect toc.esign, programming and use of robots for humane purposes.e earliest robots of the 1940s human communication with them has been aand progress over the ensuing 50 years has been great. Control ofhas changed from crude cables to myoelectric signals and speech. Controltors for hazardous environments such as nuclear plants, space and underseafrom simple on-off control of individual joints to high-level supervisoryvarious kinds, combining both analog and symbolic communication. Theindustrial robots, which can now make movements very much faster and:han can humans.not my intent to review that progress, though it is clear that as robotsbecome more intelligent the nature of communication between the humanrobot is becoming less and less like that of using a passive hand tool andlike the relationship between two human beings.are what I consider to be my eight ultimate challenges of human-robotI may change my mind tomorrow. Others certainly have other candidates.human physical /social interactions by telepresence

T h s is the basicet al. 1989). Oneeven though thcTeleconparticipants, bu;People in differentlearning or otherAn expertmake use of hismusical instrumentA person onbillion dollarstransfer is required,biopsy or aThemass transfersite. Progressrobots with highHowever avaikblechannels such as

IEEE lnterr ational Workshop onRobot an d t uman Communication0-7803-4076-0,97/ $10.00 @ 1997 IEEE.

challenge of virtual reality and telepresence (or tele-existence, see Tachiwould like to have direct physical interactions with people and objectsse other people are located some distance away. There are many examples.?erencing technology has enabled teleconferees to see .the remotenot yet to touch them, or more particularly to touch objects in common.locations would like to engage with one another in sports, or in groupsocial interactions, in a natural way.in some skill, say surgery, or maintenance of a machine, would like toskill at a location other than where he is. A teacher of some skill, say aor a sport or surgery, would like to teach a student who is elsewhere.eazh would like to explore a planet, and society would like to save the 400or so required to send a human to Mars. Of course when actual masssuch as putting a new part into a remote machine, or bringing back aplanetary geological specimen, other means will have to be found.Pathfinder planetary probe showed that in many cases it is not necessary to doexcept locally: the spectral or other analysis can be done right at the remote

has generally been good, but there remains a long way to go. Smallbandwidth feedback are now available, e.g. the Phantom haptic robot.communication techniques for medium bandwidth communicationISDN lines do not accommodate easily to closed loop real-time control.

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Experiments in the Human-Machine Systems Lab at MIT with telesurgery havestudied means by which one person can guide the hand of a different but remote person,making use of the muscle power and control already built into the latter persons armandhand, and this requiring only communication technology.There remain fundamental problems of whether telepresence (that is, the sensationof being there) is useful as compared to high-bandwidth, high resolution seeing,forcekactile sensing, and motor dexterity. No one has ever proven that telepresence isreally necessary to get the job done, or by itself enhances performance.A new form of analysis is called for, namely an optimization of the allocation ofpresence-as some mix of telepresence and real presence-for deciding how we as humansshould allocate our attention in performing our work and conducting our lives (Sheridan,1970).

2. Human monitoringhupervision of automationAutomation in manufacturing, aviation and air traffic control, and many other aspects of lifeis now a fact, and the human operator on many fronts is being moved to the new role ofsupervisory controller (Sheridan, 1992). Such a role change, however, places newdemands on the human to become a monitor of the automation as well as a keen observerwho maintains situation awareness and is always ready to detect and diagnose incipientabnormalities, and to step in and take over control if necessary. The problem is that peoplehave been shown to be very poor monitors. This is especially true if the human is forced tobecome a passive monitor rather than an active co-participant.The phrase human-centered automation has recently become popular. Generally itis taken to be a principle of keeping the human front and center as automation technologyin one form or another grows.Unfortunately human-centered automation connotes different meanings to differentpeople. Below are listed ten alternative meanings (Sheridan, 1996), all surely somewhatidealistic. For each alternative meaning a restrictive qualification is added in parentheses,which to the writer seems necessary. When the alternative meanings of the phrase areexamined, we find the substance of human-centered automation thin, and the realpotential somewhat questionable.1. Allocate to the human the tasks best suited to the human, allocate to the automation thetasks best suited to it. (Some tasks are too simple to bother automating, while some are sodifficult no one has any idea how to program them. See further discussion on this pointbelow .)2 . Keep the human operator in the decision and control loop. (The human can handle onlycontrol tasks of bandwidth below one Hz and exhibits severe limits in sustaining attention.)3. Maintain the human operator as the final authority over the automation. (This is notalways the safest way. It very much depends on task context.)4. Make the human operators job easier, more enjoyable, or more satisfying throughfriendly automation. (Operator ease and enjoyment dont necessarily correlate withoperator responsibility and system performance.)5. Empower the human operator to the greatest extent possible extent through automation.(Operator empowerment is not the same as system performance.)6. Support trust by the human operator. (Too much trust is just as bad as not enoughtrust.)

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computer-based advice about everything he or she should want to

human error and keep response variability to thevariability enhance learning. Darwin

know.

9. Make thealways. For10. Achieveby explicitMore will be

operator a supervisor of subordinate automatic control system(s). (Maybe notsome tasks direct manual control may be best.)the best combination of human and automatic control, where best is definedsystem objectives. (Dont we wish we always had explicit system objectives!said of ths below.)

these many dilemmas? I think we will be coping with human-centeredsome time to come, though some new phrase may become fashionable.humans and computers with models of each other

Mathematicaoperation, foiand so on.model, a hylPresumably ihow the proccascertain somIn any case tkevalid mental Ivery poor memodels, partica mental motuned in to

It WO\and what hemeasured facutterancesorThe ic

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models of physical systems have proven extremely useful in systemsexample as observers or Kalman filters in control, as world models in AI,ognitive psychologists have in recent years invoked the notion of mentalothetical internal representation of how some physical process works.mental model can be used as a referent for asking logical questions aboutss would respond to various inputs. However, we lack objective means toones mental model, other than asking him or her to describe it or draw it.concept appears to be useful and gaining in popularity.erpert human operator of some automated equipment presumably has someode1 of how his equipment works. However a novice operator may have atal model. We need to assist operators in having and retaining valid mentalularly when the computeror automation system is complex. We might call itel support system, and its function would be to keep the human operatorhat the automation is now doing, feeling, thinking or planning.

Id also be useful if the computer could have a mental model of the human,or she is doing, feeling, thinlung or planning. This might be based onal expressions or other body language, or upon inferences from past verbalast behavior in operating the system.eal would be analogous to two people who know each other well, and can

4. Helping1 humans decide what they want

pick up subtle

a computer plus a robot cannot perform- nce thatExcept for one. That is the function of deciding upon goals, criteria,objects or events, in other words specifying a utility function or anMachines dont seem to have values, unless of course they arethem. Values seems to be a uniquely human quality.might assert that the humans most basic underlying values andfor example survival, and all expressions of day-to-day goalsthe basic goals-in that sense humans too are programmed.

cues from one another in order to collaborate. Husband and wife often

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In any case, the functional specification of objectives is not easy for humans. Infact when the objects and events they are to consider and evaluate are new ones, ones withwhich they have no experience, it is close to impossible for people to judge utility orrelative worth.If two alternatives are being compared and they are the same in all respects but one,the decision is relatively easy. One alternative is said to be dominated by the other. Butwhen all dominated alternatives are thrown out, one is left with a set of alternatives which,when plotted in the space of the attribute variables, form what is called a Pareto fron tier,along which there is no apriori basis for asserting that one alternative is better or worsethan another, except by reference to a utility function. Keeney and Raiffa (1976) haveexplicated a theory of decision in such circumstances. March and Simon have asserted thatin real life people do what they term satisfice: namely, they narrow their preferences to aregion on the Pareto frontier where they are satisfied, and they are not interested in furtherrefinement of their preferences.When it comes to malung decisions in attribute spaces of more than 4 dimensions itbecomes difficult even to satisfice. Here is where computers can help- by renderingalternatives in juxtaposition to one another and letting people observe the implications oftheir ordinal and cardinal ratings of relative worth (Charny and Sheridan, 1986). This is awonderful new opportunity for computer graphics and virtual reality. The market will beslow to develop, however, because decision and policy makers who make strategy fortechnology application will be slow to understand the problem.5. Allocating normal functions between human and machineThe designer of automation and robotic systems must at some point make decisions aboutwhich functions will be served (which tasks will be done) by humans and which bymachines (computers, robots). It is already quite clear that the humans functions areevolving away from direct hands-on manipulation and control and toward that ofsupervision -planning, programming the computer, monitoring the automation,diagnosing and fixing failures, and learning/generalizing from experience (Sheridan,1992). The question is whether there are objective means by which to allocate functionsbetween human and computer/robot, and indeed whether designers can aspire to some formof optimization.I am inclined to be pessimistic about optimization of function allocation, much as Iam pessimistic about optimization of any complex system for which few constraints arespecifiable in quantitative terms, and the elicitation of an objective function in thehyperspace of salient attributes staggers the imagination (as just mentioned above). (This innot the same as optimization where reality is modeled in terms of relatively few variablesand simple objective functions are assumed-sometimes because they are mathematicallytractable, such as quadratic criteria are assumed in modern control.Automation technology is changing rapidly as are societys wants and needs, andthe only way to discover what new machines can do under new circumstances is to trythem. Failures are bound to occur, but that is the only way we learn. Darwin called thisvariability due to new testing requisite variety. When coupled with the successes andfailures the whole process is called evolution. I am a believer in design evolution.This is not to say that we should not work hard at developing predictive models andbring some modicum of order to the process of function allocation. We must try, for thestakes are quite high in terms of system performance.6. Allocating authority at a time of crisisAllocating functions between humans and automation for normal, usual, expected eventsand demands may be difficult. But the problem of allocating function when events are

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d unexpected is at least as difficult, and quite different. It might bem of allocating authority between computer and human at a time ofrecedents at the extremes of decision bandwidth. In nuclear powerds be dropped between the fuel rods instantly whenability are met. There is no time to wait for humanon. This function has been made automatic, an no one disputes its

me are decisions to launch nuclear missiles, or to take otherund social and political implications. Those who have evenactions be automated have been quickly outvoted. Some amount ofamong multiple persons is absolutely called for. There is fms lots of room for weighing the human against the computer.quick decisions and take rapid actions which may bed computers can make stupid blunders out of ignorance of

the more time there is to make measurements and performsis of what has gone wrong. At the same time the longermay get and the greater the difficulty in fixing it. So therean be addressed by mathematical modeling- if the systembabilities and costs of consequences can be assigned.uations automation can be triggered to perform certainme and take off the heat of having to make a quicktion that should be explored for anticipated failures. Inell ahead of time, simulators can be used by humans tocide what to do when system state reaches the critical

dicted are the most troublesome, by definition. Itrs to invest effort in trying to anticipate classes oftected, and consider from the outset alternative roles

The phraseobserve differentover delayedend must join:lyare fighting ojdecisions ofinteracting(which can bedifferent decis.onmaking agent.Weespecially forcognitive science

Distributed

7. Controllfng the chaos of mixed initiative and distributed interactiondirtributed decision-making refers to multiple humans or artificial agents whichsubsets of the total state information, must communicate with one anotherand/or inadvertently limited bandwidth communication channels, and in theallocate common resources or take other coordinated actions. Exampleslarge fires such as forest fires, national disasters and war, and marketingmulti-national corporations. Another example is supervising multiplerobots or automatic systems where each of the latter has a different set-pointadjusted by the supervisor).decision-making gets even more complex as the various agents havecriteria, and as both humans and machines assume the role of decision-need models for understanding the behavior of distributed decision-making,Currently neither computer science nor

These are sometimes called mixed initiative systems.systems with mixed initiative.has much to offer.

For many yearswhich are able8. Maintainling peace in a world of mobile malevolent telerobots

I have been troubled by the spectre of a world filled with mobile telerobotsto wander in every street and back yard, swim in the oceans and rivers and

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streams, fly in the air, and even crawl through sewer pipes. Telerobots today are doing alof these things. There are no technological breakthroughs required, only refinements onexisting technology.Quite clearly such telerobots can and already are spying, and can easily do sabotageand more dramatic forms of destruction. That is why military organizations around theworld are developing land mobile, submersible and air- and space-borne telerobots asrapidly a they can. The laser guided missile is only one form of such device. We will seemany more in the near future.In classical engagements of force between adversaries the soldiers wore brightlycolored uniforms, rode atop horses, carried flags, and played horns and drums as theymarched into battle. It wasnt always safe, but at least such actions testified to their braveryand signaled that they were ready to sacrifice themselves for their cause. Then braverybecame compromised by survival instincts: in recent years soldiers don camouflage, rideinto battle inside steel tanks or fast-moving evasive aircraft, and perform their duties atnight or when unexpected-but they still risk their own bodies to the cause, though withsome protections.Now all that is changing. Soldiers will no longer be soldiers in the old sense, theywill be supervisory operators of telerobots, programming them and then monitoring fromafar. As the telerobots do their dirty work, the soldiers will not risk their own bodies, andin many cases will be immune from the pain and suffering that their telerobots are causing(pain and suffering signals are hard to provide in the state feedback!). Furthermore thetelerobot itself need not have a national symbol emblazoned on its side: that is non-functional. The telerobot can be anonymous, with encrypted instructions coming from itssupervisor, providing no practical way for others to trace its origins or source of control.As such telerobots become cheap they need not be in the employ of wealthynations, whom we would suppose might bear some responsibility and pride in their ownmoral standards. They can be put to work by lone or crazed terrorists.This is not a happy picture, but it is our technology, and I think together we bearsome responsibility to control it.

ReferencesCharny, L., and Sheridan, T.B. (1986). Satisficing decision-making in supervisorycontrol. Unpublished paper. Cambridge, MA: MIT, Man-Machine Systems Laboratory.Keeney, R.L., and Raiffa, H. (1976). Decisions w ith Multiple Objectives: Preferences andValue T radeofls. NY: Wiley.March, J. G., and Simon, H. A. (1958). Organizations. NY: Wiley.Sheridan, T.B. (1970). Optimum Allocation of Personal Presence, IEEE TransactionsSystems, Science and Cybernetics, Vol. SSC-6, No. 2, pp. 140-145, April.Sheridan, T.B. (1992). Telerobo tics, Autom ation and Hum an Supervisory Control.Cambridge, MA: MIT Press.Sheridan, T.B. (1996). Human-centered automation: oxymoron or common sense? Proc.ZEEE Intemational Conference on Systems, Man and Cybernetics,Vancouver, Canada.Tachi, S., Arai, H. and Maeda, T. (1989). Development of anthropomorphic tele-existence slave robot. In Proceedings of International conference on AdvancedMechatronics, May 21-24, Tokyo: 385-390.

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eight ultimate challenges of human-robot communication

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