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Virtual and Mixed Reality in Telerobotics A Survey

ndustrial Robotics- Programming, Simulation and Applicationsof interacting within this world The auxiliary information that can be conveyed through thevisual, haptic, or other form of display of virtual models may facilitate the user to perceiveertain taskneral VR promises to revolutionize the way human-computer interaction systemsto lead to the creation of excellent tools making executiomplex and demanding tasks more easy and intuitive for the htVirtual, Augmented and Mixed Reality technologies are nnized asbreakthroughwide spectrum of apusually via a computer interface and a computer network, is one of the fields thatbiosis (Vertu &z Coiffet, 1984)deas which have beenthan twd hmechanisms in hostile enyderwater or for other difficult or dthen of VR techniqbeexplained further in this chapter, constitute basically:(a)a generalization of theth the problem of time delay and stabilityteleoperation systems, and(b)an attempt to provide human operator assistanceachieve better transparency characteristics for the teleoperationother hand thet ofbroadlyetworking technologies, such as those related to the Internet, and the numerotevant appInternet technmutually befrom ideas developed ins In fact VRT ande fieldnis merging of technological potential can lead to a generalization of the concept oftelework, where remote control through theork of actual pbe possible

One can even think, for instance, of supervising and actively controlling aobjective must be of course to enable and ng to move from his home A major researchle manufacturingso that wideulationn finally take benefit of these technological advancesAt the rest of this chapter, we focus on analysing the theoretical foundations of this field andtheical application domains thatinvolved, by presenting somecharacteristic case studies Section 2 starts with a description of the basic principles related tovirtual and aud realityoverview of applications related tothe field of robotics In Section 3 we describe the basic concepts that govern telerobotic systemsand present a historical survey of the field Section 4, then, presents typical application scenariosof these technologies, related to the two main robotic systems categnamely robotpulators and mobile robotic vehicles, and highlights the link with the new VR-based fieldof haptics Concluding remarks and future research directions are given in Section 5

Virtual and Mixed Reality in Telerobotics: A Survey447ese features (ie providing perception,or action assistance to thehuman operatosystem within the masterntrol station and are generally ded bytrtancee kindde thedhinddofInel one could then think of a telerobte tasexecution, with active intervention only in extreme error recovery sitns All theseparadigms are generally grouped under the term supervisory telepdescribedaradigms is illustrated in Fig 3 The interaction and mergitures with the hd skthat will Ito the creation of more advanced telerobotic systems, capable to perform moremplex task such as then systems, to find the"optimumbetween robotrator control in order toin a full extent theh32 Web-Based TelerobotUntil quite recently, that is before the last five to ten years, telerobotic systems weted through dedicated fastxclusively reserved to trained specialists

The integratpidly evolving media/network technologies, especially the Internet andWide Web technologies, promises to open the door to a much wider audience, by creatingn domains Controlling a real distantInternet and performing a physical process in a(as opposed to simpleinformation processinghaving a significant impact in many aspects of both social and economic life This sectionpresents a brief survey of such web-based telerobotic systems Situating the current state-of-ising and challenging research area, is of particularly interest within theouter connectedhe Internet Remote control of these systemsstandardbrowser incorporating the human operator control interface Even though therover the Internet, issuing simple motion commands to perform elementary tasks A typicalle is the Australia's telerobot, developed at the University of Western Australia?2 It

ndustrial Robotics- Programming, Simulation and Applicationsconsists of a six-axis robot manipulator,controlled with one fixed observing cameraThe initial system, originally demonn 1994, required users to type in spatialtor either to choose from a prespecified set of target positionsclick on the image andot motion commands relative to the position of aroblem of course still remains to associate the position of theaggedD image, with the position of the robot end-effector and the other obirld ather very good example of a robotic manipulator being controllePumaPaint system(Stein, 2000), whichon-line from June 1998March 2000 Itpaintings created by the user on a virtual canvas, which was incorporated in the user interfaceards all commands to the robot so that almostime image appears on theThe system also provides visual feedback in the formperiodically updated live images from the roboesides these systems consisticontrolled throtthe Internehere is another class of web robots involving telepMost of these systems provide exclusive remote control to a single person or proffice building, controlled through the web, was Xavier(Simmons, et al, 2000) Tas soon become very popular with more than 40, 000 requests and 240 Kilometers travelledto date! The command interface of the robot provides a discrete list of destinations to sendts a task request, thist back indicating whenthe robot will most likely carry out this task If the user had registered using a correct e-mailaddress, the system will send an e-mail after completion of the requested task In addition tongthe floor the robotthery interesting application of such web-based systeolves remote control of mobing in a museum

These are called tour-guide robots (Thrun et al, 1999), like the00O), installed successfully in the Smithsonian's National Museum of American History Theseobots are operated either under excor under shared control by both real (on-site)and remote(virtual) visitors of the mtclusive web control, the user interface is implemented as one Java applet incorporating a mapand two live images, one from the robot and the other frorhervas shared control interface was on-line for g1 hours andby 2885 people The robot travelled 385 Km under sharedroL, providinginformation about 2390 exhibiThere exist many other Web robots on the net, performing a variety of tasks such as thosedescribed in( Goldberg, 2000) The NASA Space Telerobotics prehttp://ranieroacthgnasagov/teleroboticspage/realrobots,html

rtual and Mixed Reality in Telerobotics: A SurveyO Real Robots on the Web Reviewing all those web-based teleoperation systemsit is clear that the mainthe unpredictable and variable time delay formunication over the Internet which calls for theontrol or off-line teleprogramming scheme to ensure stability Most of the systemsrrently available on the web incorporate user interfaces, which implement basifunctionalities, such as enabling the user to choose from a prespecified set of tasks (e, gtarget locations) These interfaces use some combination of HTML forms or Java consoles toenter data and issue simple commands for immediate or future execution Sensory feedbackis usually limited to the display of images that are captured at the remote site, and thepresentation of some status information in text form

It is obvious that this sepaetween the actions of the human operator(user) and the response of system fed back brthe remote robot deteriorates the transparency and telepiperation system More advanced"interactive telepresence" techniques need to bemore natural, intuitive and direct, real-time interaction between the user andeb-based teleoperation systen4n Telerobotics: Application ScenariosAs already stated, vr can be usedof advanced multimodal human/ machinetechnologies, VR can be employedmediator" level between the human-operator and theremotely controlled robotic system The performance of any telerobotic system can be measuredterms of two, often contradictory, indicators:emote robot environment and theby which he can perform the remotask via the telerobot, and(b)Stability, particularly in the presence of large time delays in the bilateralommunication and control loop that can jeopardize smoothness of operation,especially when force-reflecting bilateral telerof using VR interfaces as mediators in human-robot interactive comystems would thus be twofoldturalness and intuitiveness of(i)enhancinginformation visualization via virtual andented reality displays, (iiting theof multimodal sensori-motor interfaces taking into accountof all these being, therefore, to improve transparency of the telerobotic system,acilitating the task from theaugmented reality models, and (i)byoff-line teleing scheme based on a virtual representation of the remote taskiRonmenbeing, here, to improve stability of operation and robustness forthe telerobotic system

ndustrial Robotics- Programming, Simulation and ApplicationsFig 4 TAO 2000 VR based telerobotic interface(CEA, france)es of vR-basedsystems, for the two main classes of robotic systems, namely: (a)robot manipulators, and(b)41 Robot telemanaterial), and space telerobots (long-distance telemanipulation) The French Nuclear Centre(CEAactive in the field since theleoperation history One of the most recent advances is the TAO 2000 system, a VR basedning interface, for nuclear servicing using a master-slave robot telemanipulatorem

The whole system is illustrated in Fig 4, with the graphical tele-programming interfac(left)and the master force-feedback manipulator arm(MA-23, on the right) G Hirzinger and histeam(1993)at DiR have developed a multisensory telerobot and conducted the first actual spaceby astronauts, as well as telerobotic ground control using either on-line direct teleoperation or, whattermed, a telesensor progranSince then, numerous telemanipulation systeive been developed, applying variousmethodologies adapted from the field of virtual and augmented reality, with manycale telemexamples of vR-based robot telemanipulation systems based on thet systems, and(b)a distance training(remote/ virtual laboratory) system, forobot manipulator programming using a multimodal VR-based web-enabled4On October 10th 1996, a teleoperation experiment was performed involving four robotPoitiers, Grenoble and Nantes in France, and Tsukuba in Japan) The robots weteleoperated simultaneously (in parallel) by the master control station situated in PoitierGermansearch Establishment, Wessling

rtual and Mixed Reality in Telerobotics: A Surveyfaming theeriment was the first general one of a research cooperation programme named TWEe World Experiment) linking seven research tearlonging to five countrim, the Laboratoire de robotique de Paris in France, and the mechanicalhe main challenge of this"telework exibility offeredVR technologies to ameliorate the hioperator master control interface and enhancehe capabilities of such robot teleoperation systems With four different robots controlled inkinematic dissimilarities and consshowsof the experimentaluP, with the master control interfaces, and two robots in parallel operation(one in Francepan) As can be seen in this figure, the task consisted of assembling a four-pwithin a fence on a table The operator performs the virtual puzzle assembly usingown hand and skillthe mastfeedback is local and concerns only the graphic representation of the remote task featurobot, Theor/ ve interaction parameterorkstation in order to derive robot actions(graphically represented for softwnd results visualization) and does notecove, direct operator action/ perception AThe ultimate goal of such research efforts isle that vR concepts andterraces betyhumans and robots

In the direction of ameliorating the transparency ofthe telerobot system, which constitutes a major target as has been already stated, such ahuman-robot interface must enable the hioperatto remotely perform the desired task in a natural and intuitive way, as if he was physicallyesent at the remote(slave robot)site, without feeling obstructed or constrained by thehis manual dexteritydesiredmeaning that the system must support natural skill fransfer between the humanrator and theotely controlled (slave) robotTo approach these key objectives, it is particularly important for the master teleoperationenvironment to display information to the human operator not in a static way but through amultimodal/ multisensory dynamic interaction environment VR concepts and tools play anificant role in this direction Particularly, interacting via the (active) sense of touch is ofprimary important This is termed"haptic interaction, or haptics, which isery activedevices, often termed"data-glovesforce-feedback gloves" if applicis illustrated in fig 6, where thman-operator wearing a specially designed exoskeleton device on his hand (the LRPactions performed within this vr simulation environment on the masterntrol site are transformed intoa robotmanipulator to execute, and are then transmitted to the slave robot site(s)

ndustrial Robotics- Programming, Simulation and ApplicationsFig 5 Multi-robot long-distance teleoperation experiment (adapted from( Kheddar et alThis genept according to which,ideal telerstem the huthe task instead ofthe context of the mulbot teleoperation experiment depicted above in Fig 5德irtual Task eRobot→RobThe idea here is to let the human operator concentrate hisonly on the task at hand andn both the robot control and the task The human operator is, thus,onstraints imposed by the robot mechanisms(e

g kinematical dissimilarities, etc ) Such issuese resolved by the system and are transparent to the user, giving him the opportunity to bettertask to accomplishrpret correctly the human manipulativeperformed within the masterrtual environment It must analyse these actions, extract the critical task parameters and deducein real-time, inof directperation or offline incommands that need to be sent to the slave robot for execution

Virtual and Mixed Reality in Telerobotics: A Surveycomplex decision problems, and (b)on the other hand, the capacite 2 t B ools in the control ofWe can thus conclude that the application of VR-based concepts and toorobotic telemanipulation systems, aims principally the developmentan-robot interactiverobot manipulatorsspeed andombination of sensor-based primitive tasks412 Distance Trainilator PrograSubstantial application scenarios of vR technologies can be found in the field of educationthese technologies are combidevelopment of very efficient remofe and virtual laboratory platforms, aiming to enabldistance training in a number of engindisciplines

One such appliting a platform thatany remoInternet Access toand other similar mechatronic devices and laborapecific time restrictions or even not provided atfactor is the high cost of such equipment, which makes it very difficult for mangineers Therefore, the benefits from providing a means for any-time/any-place(virtualdyor remote)experimentation, in a"lab facilities sharing context, are evident from at of view related to theleteness and quality of practical training possibilities offered to their students2D GraphicalFeedback Panelboxx posit pStatus PanelFig 7 The graphical user interface of the virtual robotic laboratory platf

Virtual and Mixed Reality in Telerobotics: A Survey2 virtual and Mixed Reality: General DescriptioDuring the last ten to fifteenVirtual Reality (VR), as a theoretical and appliednd entertainment media Howethe latter often results in an"abof this termich is probably due to the lack of a formal definition of the field In the sequel, weattempt to describe the basic principles that govern the field of VR, as well as of the moredomain of Augmented and Mixed Reality syand we give alated applicationsIn an attemtdefine whatin relationbelIne In(a)computerted, three-dimensional realistic visualization space, enabling(b) real-fimmend multimodal interaction involving multiple sensori-motor channels of thefactor here is, thus, the stimulation of huexperience to prodimpression of something that does not reallsome extent, human imaginationas a real world The three important dimensionscharacterizing VR systems, and differentiating them from typical computer simulationvironmentste a sevirtual preand realism(Burdea Coiffet, 94)Virtual Environment(VE) created via graphics is a communication medphysical and abstract components The three basic constituents of a VE are the content, thegeometry and the dynamics(Ellis, 1995)

The content consists of objects and actors The geometry isdescription of the environction,and has dimensionality, metrics (rulestablishing an ordering of the contents) and extent (range of possible values for the elements ofthe position vector) Dynamics is represented by the rules of interaction among the vE contentsdefined to be theby whiclto represent ob

jects in environment other than that frthe impressions physicallyThe threeSensors(eg head position tracker or hand shapheadphonesal purpose hardware and software(connecting thrs and effectors inch a way as to create experiences encountered by people immersed in a physicalThe heract with a veans of head and body referenced displays, the success depending on the fidelity withhich sensory information is presented to the user The environment experienced by theuser via a VE simulation is of course imaginary On the contrary, when referring to a

ndustrial Robotics- Programming, Simulation and Applicationsassist him indesired physical task Insuch teleoperation interfaces, real and simulated dataocessing to produce intermediate environments of real andThe mixture of real and virtual entities within the same environment refers to augmentedlew field that has evolved as a special category ofbed in the frobotic device etcFig 1 General structure of VR-based human/ machine2

2 Augmented Reality: Basicsmented Reality (AR)syonstitute in fact a categoryecialized vRhich have attracted significant interest during the last years due to thenumerous applications they find in various new domains While vR has as the main goal toasic principle of AR systems is to enable the user to expee simultaneouslctual (real) physicalIn other words, Arlements instead ofThe question is then: why has thfield of ARound sueinterest within theand where does the usefulness of such mixednvironments reside? The answer is that virtual environmentsdisplay various data encoding complex information related to theorld, informationthat is not directly accessible in reality and could not be perceived differently from thebeing One can say that dispthis information which ised byofirtual objects,t"amplifies" the perceptual capacity of the human being, increasing theabilities to perform complex tasks on the real worldThe application domains of AR systemsnstantly evtions, like simulation for educatiin medical (invasive or not) procedures, as well as pre-operative planning and computeraided (image-guided) operations, (b) CAD and mantfacturing processes, for instancechitectural design of a new building and "previewing" its spatial integration, training inmaintenance proceduetcry, egproduction of special effects, virtual actors etc Military applications are, unfortunately, also

rtual and Mixed Reality in Telerobotics: A Surveynot excluded In the following section, we present a short overview of VR and Arttroduction to the use of such technolrobotics, whscope of this chapterFig 2 Programming of a robot manipulator using augmented reality(AR)technion ing virtual model (3D wireframe graphics above)on real robot image (adfrom: Rastogi et al, 96)2

3 Overviewrtant domain where VR and AR technologies find many and interestingthe field of robotics and robot integrated manufacturing systems It isasserted that the use of such technologies can provide significant benefits in all theases oflufacturing procedure, from initial design to implementation and controlparticularly when these involve the integration of robotic systems As outlined previouslyVE constitutes in facttegrated hramnan-machine interaction system, VRontribute significantly in all the processes where human intervention (and human factor ingeneral) plays an important role, like for instanceharacsgn of virtual prototypes and the evaluation assessment of variecteristics (including aesthetic, ergonomic etc )and parameters related toncy of opeth the goal beingbetter exploitevaluate complex situations and solve decision problerch as task and patholving a robot maniOneusefulted appln of ar concernamming of robot manipulationtasks The basic idea resides on thef virtual modelsonment as an intermediate representation to guide and assist the robot action planningmodels, representing the robot and the planned motionthe actual task environment, enables the htoperatorion, potentially off-line, facilitating theprogramming and validation of complex robotic tasks, without the need to constantly workwith the real robot in an on-line programming scheme (with all the advantages that such an

ndustrial Robotics- Programming, Simulation and Applicationsf-line robot programming presents in practical scenarios) OfVR models must beorrectly superposed on the real world images, for such systems to be of any practicalThis is called 3Dation which constitutesthe basicblems that needs tobe tackled in any AR system, based on camera calibration techniques, and probably makingof (image- or sensor-based)3D tracking methodologies (if such a systo operate ineal-timeFig 2 presents an application example of such an AR-based programming of a robotanipulation task(Rastogireal robot which is overlaidal robotnage views assisting the human operator to better evaluate the anticiprogrammed action sequence In this case, the task consistsasping an object andperforming a"pick-and-place"operation Fig 2(a)shows the"predicted"path of the robotd using this ar interface filew with the robot manipulator having moved according to the planned operation, withboth real and virtuales being registered (ie

correctly aligned), demonstratingscheme It musthere that the additionaluse of stereoscopic images with 3d graphical models can significantly enhance the efficiencrobot programming tasks, by providing visualstem(redfalse nBased on the above concepts, virtual and augmented reality techniques have evolvedally during the last decade finding significant and interestingand practical foundations of this domain form thescope of this chapter ande thorns3 Teleroboticsstoricauman operator to perform from a distance a manipulative task, using his own hand through theintermediate mechatronic system Telemanipulation controltask, besides its fascinating character related to the notion of extending human capabilitiessome tool beyond usual space or time limitshuman intervention is indispensable to perform a task taking place in an unstructured"hostiltasks, and the complex task/path planning required for timely andmaster-slave telemanipulation systems consisted of a couple of mechanical or electromechanicaled the master contrby the human operator, and the other, called the slthe remote manipulation task) Bilateraland forceas initially ensured through a mechanical linkage and, later-on, through the useectrical links andcontrol loops In its infancy, telemanipulation technology foundications in the nuclear industry for the remote manipulation of radioactivterials in environments where human presence was hazardous Typical example is the workcomplished by Raymond Goertz at Argonne National Laboratories, USA, or byVertud the French group at the CEA(Vertut Coiffet, 84

Virtual and Mixed Reality in Telerobotics: A SurveyBilateral servo-controlled telemanipulation and industrial computer-controlled roboticere two technological fields developed originally in parallel and, in some extent,hat is gerdescribed under the term of telerobotics Robotics was initially concernedwith the development of industrial manufacturing systems perforepetitive operations in an autonomous sensor-based manner, while telemanipulation wasocusing on a different class of tasks, which should clearn the predominant presencese general technological fields,challenging and promising research field, whichms at exploiting in a full extent both human operator skd machine intelligencehin a human/ robot interaction and cooperation contextThe integration of some mobility characteristics on a remoteextended the workspace and, generally, the functionality of these syin terms of sid task limitations, and has led to the creation of neythe more broad term of teleoSuch application domains include the development ofbile telemanipulator vehicles for space operations(e g Mars Rover etc ) with typicales being the mobileqo ploration missions, Underwater remotely operated vehicles(ROVs) have also beerdescribed in (Gracanin valalong to the general field of intervention and service robotics, which focuseslevel human supervision Such systems aim mainly at substituting the human being in thetion of hazardous(eg handling of explosives), painful (eg

liftingghts, forinstance civil works), or else boring every-day tasks (eg vaning etc ) In section4 2, we will present one examsuch a mobile service robot This general field alsoomprises systems that aimsisting humans when performing delicate operationsrequiring increased precision, which is the case of the research performed in the field ofproblems encounterome existing solutions, methodological approaches and guidelines proposed in the literature, inrder to situate thestate-of-the-art of research carried out in the field of telerobotics Themajor problem and certainly the most cited one is the presence of time delays in the bilateralInication loop, which is mainly due to the distance separating the master from the slavesite, but may also be due to the procesdue to the load of thewhich is the case of the Internetusing additional difficulties inwith the problem For instance, time delayanscontinental teleoperation when a satellite link is used may exceed 1 second, while whenteleoperating a rover on the moon, round-trip time delay approaches 3 seconds The humaperator is in such cases obliged to apply a move-and-wait strategy, that is, to make smallaiting for the images(and in general, the sensory feedback) to be updated As a(seeforinstancehttproboticsiplnasAgov/groups/ry/forabriefsurv

ndustrial Robotics- Programming, Simulation and Applicationsconsequence, communication time delays cause certain degradation of the teleoperation sysperformance: but what is even more critical, their presence may jeopardize safe operation andluse dangerous instabilities especially when force-feedback is involved in a long-distanceDegradation of sensory feedback may also be due not only to the presence of time delays andlimited bandwidth, but also to noise and other sort of disturbances in the comrchannel Problems related to the quality of sensory feed back may also derive from the nature ofthe task itself, for instance when a slave robot operates in low visibility conditions (eg videoter remotely operated vehicle, whichmpletely useless or extremely difficuwhen sensory feed back isdeteriorated, due to time-delays, noise or other source of signal degradatictask-specificethodology or advanced remote control strategy has to be followed to assist the humanoperator to perform the task goals, and ensure safe and efficient operation of the systemTime-delay has long been known in classical control theory as a very challenging problem, andrious predictive control schemes have been proposed based on some a-priori knowledge of thedelay (for instance, the predictor of Smith, proposed around 1956,In the teleoperation field, more recently, some new control schemes have been proposedto cope with this probty theory(Anderson Spong, 1992)oncept of adaptive impedance(Niemeyer Slotine, 1991)All these approaches converge to thearency(defined in terms of force/trajectory trackime trade-off between these characteristics has to be achieved most of the times

all theseing the master with the slave, that isdiminish the control bandwidth of the systemteleoperator This ensures the stability (passivity) of the system, under some constraints related tothe magnitude of the time delay, but has as a counter-effect to deteriorate the transparency of theteleoperation system(for instance, the human operator does not feel the real profile of the forcegenerated at the slave site) The problem becomes evendifficult when time-delay israndomly varying, with no a-priori knowledge available on its order of magnitudeying to cope with the problem of commtbased on the use of predictive displays Graphical predictors, supplying visual cues(estimationsthe usual video feedback provided to the huma raphical model of the slave robot, oveta ae evolution of the teleoperation task, are the mostan operator This combination of both syntheticand real images(that is the display of a graphical model, directly following the movements of thehuman operator and showing what the state of the robot will be before the actual delayed videofrom the slave site) greatly facilitatperator The paradignf graphical predictive displays has been greatly adoptedwith problems related to the presence of time delays in the bilateral communication loop but alsoto perform visual feedback enhancement and assist the human operator in quickly assessing aThe integrativirtual reality techniques in teleoperateems can beartly seen as a generalization of the concept of predictive displays described above, wherethe term display may now refer not only to the visual display of simple graphical cues, but

rtual and Mixed Reality in Telerobotics: A SurveyrvItidisciplinary scientific/ technologwhich aims to enable a more naturalthe use of multimodal/multisensoryg various perceptuo-motormodalities of the hbeing(not only vision, but also haptic interaction and auditiveedback) cantion of excelled communication systems constituting the field of telerobotics Virtual environmentulations of teleoperation systems can indeed be used as predictive models performingThisthat the human operator could be provided with realistic threeimages and perform the desired teleoperation task in a natural and intuitive way(thatfor instance, by feeling the reaction forces during the execution of this virtual task modeld all that before the actual (delayed or deteriorated) realemote slave site In fact this interaction betvirtual environment(that is, the virtual task performed by the humanr)can be usedd signals that have to be sent to the slaveal telof suchintermediate virtual representationoperation task is reported in(Kheddar et alis described, as will bedetail in sectiVR-based models of teleoperation tasks can also be usedline teleprogramming schemperator performs a virtual task in a completely simulat npletely decoupled The humanin whichthe master and slave control looenvironment representing the slave site This virtual task is analyzed and the appropriatesequence of robot commands is extracted and recorded

The sequence of commaen evaluated by the human operator before its subsequent transmission to the slavecable for all kindextrous robotictype of commands that will constitute the robot programs, whichutonomy features supported by the slave roboticthebased behaviours or elementary task operations Such approaches arepecially applied in super-long-distance teleoperation systems, for instance when guidinger on the surface of a distant planet such as Mars, Ofdea of semi-autonomoustionso be applied in an on-line directto the remote robot, instead of the traditional, continuous force/position/ speed signals Inthis general framework, Hirzinger et al (1993)have proposed the use of a tele-sensor-basedalator in space Freund and Rossmann(1999have proposed a task deduction/ action planning approach(called projective virtual realityparadigm) testedpplications, fromtasks up to the control of multirobot telemanipulation systems for space applications In

ndustrial Robotics- Programming, Simulation and ApplicationsSection 412 weample of a similar telerobotic system, but with thetion being that of aVR technology and its applications in different scientific fields have known a rapid developmenuring the last five to ten years We can now say with confidence that VR has the potential toof modem man-machine interfaces, as is the casstems

It can provide the tools and techniques to establish a multimodal, naturald intuitive human-machine interaction, increasing thetelepresence for the human operatwhich constitutes the ultimate goal ofchallenging problems have to be tackled and appropriate (generalized or task-specific) solutias well as control issues and stability of human-machine active interfacestelerobotaided teleoperation schemes, developed to facilitate the task of the human operator andde assistancefollowing wg the functions of atnsory feedback provided to the human operator and helping him to betternderstand the state of the remote task execution Typical examgraphical predictive displays, described above, or some form of artificial haptianesthetic and/or tactile)feedback Other VR-based techniques include the use ofvirtual mechanisms ( oly Andriot, 1995by performing some form of decision support function, that is, by providinggestiodications concerning thetable action plan and assist themakinby interpreting the actions of the human operator and performing a function ofbstitution or cooperation, to provide active assistance for the on-line control oteleoperation task This is the case of an active intervention of the master computtypiles being a system undertakingegfreedom (dof), or ensuring that the commands issued by the human operatortisfy some constraints related to safetyHuman Control/TeleoperationFig 3 Evolution of teleoperation systems towards intervention and service telerobotics