Robotics and Machine Perception 13.2 October 2004

ROBOTICS AND MACHINE PERCEPTION 13.2 OCTOBER 2004

OCTOBER 2004 ROBOTICS AND VOL. 13, NO. 2 MACHINE PERCEPTION

Biorobotic study of Norway rats in individuals and groups

Norway rat pups provide an excellent system for and aggregate in huddles with other pups. Rat pups SPIE International the biorobotic study of embodied, environmentally- also exhibit a negative phototaxis, locomoting Technical Group embedded, sensorimotor-based intelligence. They away from light sources visible behind their eye- Newsletter are sufficiently simple, have a protracted develop- lids. This taxis is observed for a period prior to the mental period, and exhibit interesting behavior at opening of their eyes. Rat pups’ extended sensory both individual and group levels. As altricial mam- development allows us to sequentially implement mals, Norway rat pups have underdeveloped senses touch sensors, primitive light sensors, and full- and poorly-coordinated sensorimotor systems. They blown visual sensors, building the corresponding Calendar—See page 10 are born deaf and blind, remaining so for the first control systems step-by-step. two weeks of life, and have very limited use of ol- Although pups aggregate into groups from birth, Technical Group Registration factory cues, relying primarily on tactile sensors. data modeling has shown that seven-day-old pup Form—See page 11 Individually, rat pups embody a host of taxes, or activity is independent of other pups, while ten- environmental orientations. The most salient of these day-old pups’ behaviors are coupled.1 One ques- is thigmotaxis, an orientation toward objects, which tion, then, is what gives rise to these inter-pup de- causes rat pups to follow walls, ‘snoop’ in corners, pendencies. We are currently entertaining two hy- NEWSLETTER NOW Continues on page 9. AVAILABLE ON-LINE Technical Group members are being offered the option of receiving the Robotics and Machine Perception Newsletter electronically. An e-mail is being sent to all group members with advice of the web location for this issue, and asking members to choose between the electronic and printed version for future issues. If you are a member and have not yet received this message, then SPIE does not have your correct e-mail address. To receive future issues electronically, please send your e-mail address to: [email protected] with the word Robotics in the subject line of the message and the words electronic version in the body of the message. If you prefer to receive the newsletter in the printed format, but want to send your correct e-mail address for our database, include the words print version preferred Figure 1. Comparison of rat and robot highlighting similar morphology. in the body of your message.

SPIE International Technical Group Newsletter 1 ROBOTICS AND MACHINE PERCEPTION 13.2 OCTOBER 2004

Editorial

Welcome to this, the second issue of the R&MP newsletter for 2004.

The articles in this issue cover a range of Both draw strongly on sets of low-level to the patient. The interaction in both cases topics and applications in robotics and ma- behaviours to formulate models of coop- is also via the Interent, which is also the chine perception. Learning, for example, eration. Bouloubasis et al. also emphasise medium for the online robot arena de- is a continuing theme in robotics and arti- the concept of modularity as a basis for scribed by McElligott et al.. In the latter ficial intelligence. It is represented here in systems design and reconfigurability, and case, however, the focus is on education the article by Santos, who describes efforts its realisation in the emerging area of net- and invoking the participation of school aimed at formulating theories relating ut- worked robotics. children and general members of the pub- terances to perceptual (visual) observa- Human-robot interaction is a third lic, whereas the first two articles focus on tions. The overall goal is to build machines theme in this issue, represented in the ar- the experienced professional. capable of learning tasks by observation ticles by De Gersem et al., Carignan et There are many issues that cross these of humans. al., and McElligott et al.. different articles and underpin important Cooperation is another continuing theme The first two focus on very different ap- research areas in robotics and machine per- in robotics. It is represented here in the ar- plications in medicine. De Gersem et al ception. We encourage you to read the articles by Bouloubasis et al. and May et al.. describe methods for enhancing haptic ticles and pursue the references for further The two articles offer contrasting themes feedback in order to afford the discrimi- details. in cooperative robotics; the first takes an nation of tissues based on stiffness. engineering perspective, focusing on de- Carignan et al., on the other hand, describe Gerard McKee signing robot systems for cooperation, methods for assessing the physical con- Technical Group Chair whereas the second takes a more science- dition of a patient and for performing re- The University of Reading, UK oriented perspective, focusing on mimick- habilitation tasks remotely. Both applica- E-mail: [email protected] ing cooperative behaviour observed in rats. tions offer clear benefits to the doctor and

Contributing to the Robotics and Machine Perception Newsletter

News, events, and articles If there are things you'd like to see us cover in the newsletter, please let our Technical Editor, Sunny Bains {[email protected]}, know by the deadline indicated on the right. Before submitting Upcoming deadlines an article, please check out our full submission guidelines at: 24 November 2004: Special http://www.sunnybains.com/newslet.html issue proposals. Special issues 10 December 2004: Ideas for Proposals for topical issues are welcomed and should include: articles you'd like to write (or • A brief summary of the proposed topic; read). • The reason why it is of current interest; 4 March 2004: Calendar • A brief resumé of the proposed guest editor. items for the 12 months starting April 2005. Special issue proposals should be submitted (by the deadline) to Sunny Bains and will be reviewed by the Technical Group Chair.

2 SPIE International Technical Group Newsletter ROBOTICS AND MACHINE PERCEPTION 13.2 OCTOBER 2004

Robotic rehabilitation over the internet

Robots have been explored as possible that patient’s computer connects to a rehabilitation aids in laboratory settings server on their therapist’s computer. for well over a decade. These investi- User Datagram Protocol (UDP) en- gations have recently expanded into the abled communication speeds of up to field of ‘teletherapy’ whereby a clini- 100 16-byte datasets per second. A vir- cian can interact with patients in remote tual object generator (VOG) calculates locations. However, time-delays en- the motion of the object resulting from countered in force feedback between the force inputs from the patient and remotely-located rehabilitation devices the therapist.4 An artificial time delay can cause instability in the system, and (T1 in Figure 3) is introduced between have so far prevented widespread ap- the VOG process and the local control- plication over the internet. ler to maintain symmetry in communi- The ISIS Center at Georgetown Uni- cation between the VOG and the two versity Medical Center has recently robots. assembled a robot rehabilitation To date, we have successfully con- testbed consisting of a pair of ducted the virtual beam task between 1 InMotion2 robots connected over the Figure 1. A researcher engages in a game of air hockey on an Georgetown University and Interactive internet (see Figure 1). The specific InMotion2 robot. Motion Technology in Cambridge, aims of our research are twofold: to Massachusetts. Internet delays of up to enable a clinician to assess the physi- 110ms were observed which caused cal condition of a patient’s arm using metrics the other side feels, it thus encouraging a co- borderline stability without compensation. The such as strength, dexterity, range of motion, and operative strategy to lift. wave-variable controller was found to be ro- spasticity; and to help a clinician perform co- Time-delay compensation is key to avoid- bust to variations in time delay, and perfor- operative rehabilitative tasks with a patient using instabilities in force-feedback interaction mance degraded only gradually with increasing a virtual environment intended to simulate over a distance. In our research, the wave-vari- ing delay. The degradation manifests itself as active daily living (ADL) tasks. able method emerged as the most natural ap- a higher perceived inertia at the handle which An example of a cooperative rehabilitation proach for manipulating virtual objects over the was still quite manageable even with artifi- task is depicted in Figure 2. The patient and internet.3 Instead of sending force commands cially-induced delays of over 1s. therapist ‘pick up’ opposite ends of a virtual directly, an impedance ‘wave’ command is is- We are currently testing even larger time beam by grasping the handle at the end of the sued by the master and then subsequently re- delays and examining the incorporation of robot or ‘master’ arm.2 The mass parameters flected by the virtual object or ‘slave’. How sensed force into the wave-variable methodol- of the object such as mass, length, and inertia much of the wave is reflected depends upon ogy to produce higher-bandwidth feedback to can be adjusted to correspond to real-life ob- the impedance of the virtual object: a compli- the clinician. In addition, a head-mounted dis- jects using a graphical user interface (GUI) on ant object will not reflect the incoming wave play and tracker are being integrated into the the robot’s computer. As the object is being as greatly as a rigid wall. system to allow for more realistic simulations ‘lifted’, the side that is lower will begin to feel The robots are controlled by computers run- using three-dimensional visualization. Coordi- more of the weight, thus stimulating the par- ning RT-Linux and connected to the internet nation of the haptic and visual feedback in the ticipants to maintain the beam in a horizontal as illustrated in Figure 3. When controlling a simulator is an area of ongoing research. position. Also, if one side tugs on the object, patient’s robot directly, a client application on Continues on page 10.

Figure 2. A virtual beam task realized with two robot handles coincident Figure 3. System architecture for implementing a cooperative internet with the ends of the beam. task.

SPIE International Technical Group Newsletter 3 ROBOTICS AND MACHINE PERCEPTION 13.2 OCTOBER 2004

Systems design for working rovers

A current theme in the exploration of Mars using robotics systems is the construction of habi- tats for maintaining a robotic and eventual human presence.1 A key aspect of this task is the transport of extended payloads using a set of cooperating robots. The work presented in this article is part of ongoing research in the Active Robotics Laboratory (ARL) at the University of Reading to explore networked robotics concepts for the coordination and control of multi- robot systems1,2 for such tasks. The networked robotics approach assumes the presence of a set of resources distributed across the robot platforms. These resources can Figure 1. The Active Robotics Laboratory rovers. be recruited in different architectural configurations to create, across the platforms, a set of There are a total of 17 sensor signals avail- networked robotics agents. A single robotic able on each unit, giving information about the agent may draw from a number of physically- status of the load (i.e. the amount of slide of Figure 2. The rover manipulator. decoupled robot platforms. This provides the the load within the gripper mechanism as well possibility of configuring the multiple robot as the angle of the load with respect to the rover approach sequence in which the rover will ap- systems into a single robotic entity when close body), the position of the joints and the wrist, proach and align itself with the load. When the inter-robot coupling and coordination is re- the stress imposed upon the fingers by the load, approach sequence is initiated, each of the quired. For example, the dual-robot transpor- the relative motion of the base, and the relative modules will enter its own version of that se- tation task incorporates requirements for vari- position of each of the rovers with respect to quence. During the approach, the modules will ous levels of coupling and coordination:3 the each other. Many of the switches had to be cus- collectively use the information obtained by the approach to the pick-up point can be relatively tom made in order to fit the application. sensors to judge whether a particular state in autonomous whereas grasping requires coor- The information obtained from the sensory their respective sequence has been reached and, dination and traversal requires both coupling systems is fed to a small network of three if so, to move to the next state until the ap- and coordination. microcontrollers. A design goal is modularity, proach sequence is completed. In some cases The design of the ARL Rovers shown in Fig- so if there are cases where certain sensory in- behaviors will be utilized by a sequence. There ure 1 has been customized to integrate the re- formation is needed by, say, two controllers, is minimal communication between the mod- quirements for the complete task and hence has they are both connected to the particular sen- ules and no guidance from the high-level con- a number of constraints it needs to satisfy. It is sor. Each of the modules runs almost indepen- troller. The system is set up in a way such that strongly influenced by the traversal constraints, dently and there is minimum communication each module will recognize its current state and specifically the requirement to traverse over between them. This facilitates the addition of act accordingly. uneven terrain, as well as by the fact that the modules. The communication between the The low-level controller has been tested suc- rovers trajectory cannot be perfect. As a result, modules is accomplished through a serial in- cessfully and the next stage of the work is to the load has six degrees of freedom (DOF) with terface with the high-level controller acting as integrate the sequences under the guidance of respect to the grippers. The manipulator sys- a bridge. The controllers will use the sensory the high-level controller. This stage will include tems and the two mobile bases must be able to signals to not only perform the basic control the introduction of visual guidance for the task. accommodate this ‘deflection’ and also achieve but also to form behaviors and respond in the the desired motion. way that each situation demands. A number of Antonios Bouloubasis and Gerard McKee At present, only two agents have been con- reflexive behaviors have been developed to The University of Reading, UK structed. Each comprises a mobile base, a ma- support the dual transportation task. For in- E-mail: [email protected] nipulator, and a stereo camera system. The low- stance the Grasp Behavior (GB), once enabled, level controller is built around the PIC16F873 will automatically open the fingers if exces- References microcontroller and the on-board high-level con- sive stress is detected. The behaviors can sup- 1. P. S. Schenker, T. L. Huntsberger, P. Pirjanian, and G. T. McKee, Robotic autonomy for space: closely troller will be a MINI-ITX board equipped with press basic control functions: for example if coordinated control of networked robots, Proc. i- a wireless modem. The mechanical design of the the command ‘close gripper’ is given whilst SAIRAS-’01, Montreal, Canada, June 18-21, 2001. rovers incorporates a rocker-bogie mobility sys- the GB is enabled, and if the fingers open be- 2. A. K. Bouloubasis, G. T. McKee, and P. S. tem with a passive suspension mechanism. The cause there is excessive stress in the gripper, Schenker, A Behavior-Based Manipulator for Multi-Robot Transport Tasks, Proc. IEEE Int’l motorized six-wheeled drive uses its two rear the fingers will continue to open until the stress Conf. on Robotics and Automation (ICRA), pp. wheels—via servomechanisms—for steering. levels become acceptable or the behavior is 2287-2292, 2003. The manipulators consist of three major compo- disabled. 3. A. Trebi-Ollennu, H. Das Nayer, H. Aghazarian, A. nents: a two-DOF arm, a passive but compliant First in the hierarchy of the low-level con- Ganino, P. Pirjanian, B. Kennedy, T. L. Huntsberger, and P. Schenker, Mars Rover Pair one-DOF wrist, and an active gripper mecha- troller are ‘sequences’ and each sequence is di- Cooperatively Transporting a Long Payload, Proc. nism (see Figure 2). Apart from the motors and vided into ‘states’. Once it is in a particular se- IEEE Int’l Conf. on Robotics and Automation the gearboxes, all the components were hand- quence, the robot will execute actions in series (ICRA), pp. 3136-3141, 2002. crafted. in order to achieve a goal. An example is the

4 SPIE International Technical Group Newsletter ROBOTICS AND MACHINE PERCEPTION 13.2 OCTOBER 2004

Looking for logic in perceptual observations

In his seminal work1 Bertrand Russell suggests used as input data for Progol. sure. In fact, I believe that the capacity of ab- that the discovery of what is really given in per- In particular, our interests in this research stracting general truth from simple data is es- ceptual data is a process full of difficulty. We are twofold. The first aim of this project was sential if any system is to solve new problems have taken this issue seriously in AI by applying the autonomous learning of perceptual catego- and to overcome obstacles not seen before. a knowledge discovery tool to build theories from ries from continuous data, grounding them into perceptual observation. In particular, this article meaningful (symbolic) theories. The second Conclusion introduces some of the research we are conduct- (but no less important) aim is the autonomous The final aim of the project summarized above ing on autonomous-learning rules of behavior discovery of simple mathematical rules from is to build a machine capable of learning (and from audio-visual observation. the perceptual observation of games. We shall further executing) human tasks by observing In our framework, classification models of consider these goals in turn. people accomplishing them. The preliminary perceptual objects are learned (in an unsuper- results of this research suggest that the combi- vised way) using statistical methods that en- Grounding symbols to the world nation of statistical methods with inductive able a symbolic description of observed scenes In the current guise of this project, symbolic logic programming applied to the task of learn- to be created. Sequences of such descriptions data provided by the audio and vision systems ing behavior by observation is a promising are fed into an off-the-shelf inductive logic pro- are input to the knowledge discovery engine route towards our final goal. gramming (ILP) system, called Progol,2 whose as atomic formulae. Within these formulae, Chris Needham, Derek Magee, Anthony task is, in this context, to construct theories symbols for utterances are arguments of predi- Cohn, and David Hogg are all active partici- about the perceptual observations. The theo- cates representing actions in the world whereas pants in the development of the project de- ries thus constructed are further used by an symbols for visual objects compose atomic scribed above. Thanks to Brandon Bennett and automatic agent to interpret its environment and statements representing the state of the world. Aphrodite Galata for discussions and sugges- to act according to the protocols learned. Both statements are time-stamped with the time tions. In its current implementation, our system is point relative to when they were recorded. A capable of learning the rules of simple table-top relation successor connects two subsequent Paulo Santos games (and how to use them) from the observa- time-points. The task here is to use Progol to CogVis Group tion of people engaged in playing them. Our ba- discover the relationship between the utterances School of Computing sic motivating hypothesis for assuming game- produced by one of the players, and the ob- University of Leeds, UK playing scenarios is that these can provide both jects played on the table. Therefore, we are in- http://www.computingleeds.ac.uk/ rich domains—allowing multiple concepts to be terested in the autonomous learning of the con- E-mail: [email protected] learned—and domains with gradually-increas- nection of audio and visual objects within a ing complexity, so that concepts can be learned particular context. References Some preliminary results of this research, 1. B. Russell, Our Knowledge of the External incrementally. Moreover, it has been largely ar- World, The Open Court Publishing Company, gued that games provide interesting ways of presented in Reference 3, show that the system 1914. Reprinted in 2000 by Routledge. modelling any social interaction.3 could learn accurate descriptions of simple 2. S. Muggleton, Inverse entailment and Progol, New The experimental setting used in this re- table-top games. Generation Computing, Special issue on Inductive Logic Programming, 13 (3-4), pp. 245- search is composed of two video cameras, one Learning simple axioms from observation 286, 1995. observing a table-top where a game is taking 3. S. P. H. Heap and Y. Varoufakis, Game Theory: a place, and another pointed at one of the play- We next submitted the system to the challenge critical introduction, Routledge, 1995. ers. This player will also have a microphone of finding the transitivity, reflexivity, and sym- 4. D. Magee, C. J. Needham, P. Santos, A. G. Cohn, and D. C. Hogg, Autonomous learning for a recording utterances that he produces when metry axioms from the observation of games without assuming any preconceived notion of cognitive agent using continuous models and playing the game. The purpose of the second inductive logic programming from audio-visual camera is to capture the facial movements of number or any pseudo definition of ordering. input, Proc. AAAI Workshop on Anchoring the player, whose voice is being recorded, so This research is described in References 5 and Symbols to Sensor Data, 2004. 5. P. Santos, D. Magee, and A. Cohn, Looking for that a synthetic agent can reproduce them in 6, where these axioms are obtained from noisy data with the help of a new ensemble algorithm logic in vision, Proc. 11th Workshop on similar situations. A schematic of the system Automated Reasoning, pp. 61-62, Leeds, 2004. is shown in Figure 1. that combines the results of multiple Progol 6. P. Santos, D. Magee, A. Cohn, and D. Hogg, The vision system consists of a spatio-tem- processes by means of a ranking method. Combining multiple answers for learning mathematical structures from visual observation, poral attention mechanism and an object clas- It is worth pointing out that the discovery of simple mathematical axioms from observation, Proc. European Conf. on Artificial Intelligence sifier. Classes obtained from vision data are (ECAI-04), Valencia, Spain, 2004, to appear. used to provide a symbolic description of states without assuming any explicit background of the objects observed on the table top. This is knowledge, was not set for pure intellectual plea-

Figure 1. A schematic of the experimental set-up that allows machine-learning of game rules through observation.

SPIE International Technical Group Newsletter 5 ROBOTICS AND MACHINE PERCEPTION 13.2 OCTOBER 2004

A Mars Station online robot arena

An online robot system offers visitors to a website the oppor- tunity to control a real robot that is normally located in a university laboratory, perhaps set up as part of a student project. A video stream deliv- ered to the user’s browser is normally the means by which the user can watch what is happening in the remote environment. Over recent years, online robot systems have both moved out of the labora- Figure 1. Students learning about the design of the tory, into museums for ex- University of Reading Mars Station arena during the launch ample, or they have remained of the UK Mars Stations Network. Figure 2. The painted surrounds add depth to the arena in the laboratory but encapsu- landscape. lated within specially-constructed arenas. It is benches that were put together side- also now possible to distinguish two types of ways: the top surfaces were lifted away, online robot system: open systems that are pri- and the adjacent upper-longitudinal sec- marily for public consumption, and closed sys- tions of the two benches were then re- tems that are used for recurring educational in- moved to create a rectangular bay for struction. Open systems are particularly challeng- the terrain. The bay structure is clearly ing since the designers often want to encourage illustrated in Figure 1. continuing and repeated participation on the part The actual Mars terrain was con- of visitors. These systems may also have an edu- structed on a removable wooden base cational value, seeking the public understand- to allow easy maintenance and the op- ing of science. tion of swapping in alternative terrain A notable case in point is the ongoing USA models. Sections of wire mesh were and European missions to Mars.1,2 What better bent into shape and pinned to the base use of an online robot system than to give the to create the undulations used to reflect general public some sense of the wonder and the chaotic terrain of Eos Chaos. The awe that the professional scientists participat- wire mesh surface thus created was then ing on these missions are experiencing? This covered with about five layers of paper has been the goal of The Planetary Society Mars mache and painted with four layers of Station concept, comprising a robotic rover that thick ‘rustic red’ house paint. Sand was school children and general members of the added prior to the final coat in order to public can drive about an arena that models a generate a more realistic surface. Rocks location on the surface of Mars.3 We recently were later added to the landscape. The built such an arena in the Active Robotics Labo- walls of the arena were made out of ratory at the University of Reading as part of a 3mm plywood and were painted by an project to set up a number of Mars Stations in art student with a Martian backdrop in the UK. The project was funded by the UK’s order to provide a horizon and an im- Particle Physics and Astronomy Research pression of depth (Figure 2). Council (PPARC) under its Public Understand- One of the main problems when set- ing of Science Small Awards Scheme. This ar- ting up an online robot arena is supply- Figure 3. The hoist mechanism allows the tether to track the ticle describes the construction of the arena and ing power to the robot so that it can be rover. some novel techniques we used to maintain a permanently live. A wire tether is nor- tether to the rover as it moved about the ter- mally used for mobile robots. The presence of as to control two dc motors that drive the hoist rain. The construction is in one sense simple, the tether, however, creates an interesting chal- in the X-Y plane. Figure 3 shows the hoist but nevertheless very effective in creating a vi- lenge; specifically how to make sure that the mechanism in profile. Whenever the rover sually-appealing terrain for visitors to explore. rover can traverse the entire arena without get- movement causes one or more of the switches The Mars Station arena, or ‘diorama’, mod- ting tangled up. A cable running from a point to close, the hoist moves to maintain a position els a specific geographic location on Mars. We well above the arena normally suffices, how- approximately above it. Additional stop chose to model the Mars location known as ever our arena used an alternative method based switches mounted to the arena frame prevent ‘Eos Chaos’. This is a ‘chaotic’ terrain, mean- on a simple passive-control mechanism. The the hoist hitting either end of the arena. An ing that it comprises a rugged unstructured tether is mounted from a hoist that can move additional weight, specifically a spare battery landscape with steep escarpments and gullies. in the X-Y plane above the arena. It passes pack, was mounted on the LEGO rovers (de- The basic frame for the arena was constructed through a simple ball mechanism that rests on signed and constructed by co-author Ashley from the metal under frames of two laboratory a set of four switches. These are arranged such Green) in order to compensate for the weight

6 SPIE International Technical Group Newsletter ROBOTICS AND MACHINE PERCEPTION 13.2 OCTOBER 2004

of the tether. Full construction plans for this Richard T McElligott, Gerard T McKee, References rover design are available online.4 and Ashley Green* 1. The NASA Mars Exploration Rovers: http://www.jpl.nasa.gov/missions/mer/ The University of Reading Mars Station was The University of Reading, UK 2. The European Space Agency Mars Express the focal point for the launch of the UK Mars *The Open University, UK Mission: Station network during the UK’s National Sci- E-mail: [email protected] http://www.esa.int/SPECIALS/Mars_Express/ ence Week. Since its launch, the arena has re- 3. The Planetary Society: http://www.planetary.org 4. Rover design used in the University of Reading quired only minor maintenance and receives a Mars Station: http://www.redrovergoestomars.org/ 5 regular stream of visitors each week. rovers/green/rockyA.html 5. The University of Reading Mars Station: http://www.redrover.reading.ac.uk

Biorobotic study of Norway rats in individuals and groups Continued from cover. potheses: that they are a function of differ- tion, and yields striking pup-like behavior. ential sensorimotor integration abilities, or Finally, a third class consists of a set of that they are rooted in the thermoregulatory neural-network architectures. As an initial benefits provided by huddling. We believe step, we’ve developed a two-layer, fully- that these dependencies mark the emergence distributed neural network employing a re- of social behavior, which is further devel- inforcement learning algorithm. The input oped later in life. Thus, Norway rat pups layer represents the 14 sensors, and the out- may also provide important insights into put layer the entire behavioral repertoire. group robotics. The learning algorithm adjusts input-out- Robots were designed to capture the es- Figure 2. Lateral view of robot. put weightings based on time between sen- sential properties of the rat pups: they are sor contacts, again encouraging thigmot- long, with a somewhat-pointed head that axis. With these architectures, action selec- rounds out at the nose, and have the same tion is left wholly unspecified, and sen- length to width ratio as rat pups (approxi- sorimotor contingencies develop over time, mately 3:1), where the head constitutes 1/3 rather than being predetermined. We antici- of the length. An aluminum skirt with 14 pate that all of the above architectures will micro/limit (touch) switches epoxied to yield novel results and provoke interesting brass strips allows for a 360° sensory range. new ideas, making important contributions Sensor cluster density is substantially higher to robotics and biology alike. For more in- at the nose, mimicking a rat’s sensory mon- formation on our study, please refer to Ref- tage. Since rat pups’ front legs are under- erence 2 and 3. developed and aid only in steering, they Figure 3. Similar configurations of rats and probabilistically- This work is supported by the United primarily use their back legs for locomo- controlled robots. States National Science Foundation under tion. Accordingly, the robots are equipped Grant Number ITR-0218927. using rear-driven wheels with differential drive on a single chassis. Four identical robots have been completed to date, and four more are un- aging, priority queuing, and random selection. Christopher May, Jonathan Tran, Jeffrey der construction. Currently, a subsequent gen- These separate routines provide for compari- Schank, and Sanjay Joshi eration is in the planning stages, which would sons of sensorimotor integration strategies. In Department of Mechanical and Aeronautical have more sophisticated touch sensors, ther- the absence of an active sensor, the robot ran- Engineering mal detectors, and more mechanical degrees domly chooses an action from its behavioral University of California at Davis, CA of freedom. repertoire. This turns out to have a tremendous E-mail: [email protected] We are currently developing three classes of advantage over the standard approach, where control system, with a number of variants of some default movement is selected. References 1. J. C. Schank and J. R. Alberts, The developmental each. All attempt to derive the scope of behav- A second class comprises a suite of probabi- emergence of coupled activity as cooperative iors above using sensorimotor contingencies listic architectures. These are much like the re- aggregation in rat pups, Proc. of the Royal alone. The first class is a reactive architecture active ones, with the exception that each sen- Society of London B 267, p. 2307, 2000. that employs condition-action rules linking sor is more weakly tied to its associated action. 2. S. Joshi and J. Schank, Of rats and robots: a new biorobotics study of norway rat pups, Proc. of the each sensor to a particular movement. The That is, a given sensor activation will trigger a 2nd Int’l Workshop on the Mathematics and angle of movement is roughly commensurate given behavior with some probability less than Algorithms of Social Insects, p. 57, 2003. with the sensor’s angle to the prime meridian, one, where the remaining probability is dynami- 3. S. Joshi, J. Schank, N. Giannini, L. Hargreaves, thereby encouraging thigmotaxis. Multiple sen- cally allocated to the rest of the behavioral op- and R. Bish, Development of autonomous robotics technology for the study of rat pups, IEEE Int’l sor activations are handled differently in sepa- tions. This routine takes a step toward Conf. on Robotics and Automation (ICRA), p. rate architectures, including behavioral aver- decoupling artificially-imposed action selec- 2860, 2004.

SPIE International Technical Group Newsletter 7 ROBOTICS AND MACHINE PERCEPTION 13.2 OCTOBER 2004

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8 SPIE International Technical Group Newsletter ROBOTICS AND MACHINE PERCEPTION 13.2 OCTOBER 2004

Enhanced haptic sensitivity in surgical telemanipulation Robotic rehabilitation Continued from page 12. over the internet implementation of enhanced sensitivity in the or in an infected zone. And, as surgeons are Continued from page 3. desired stiffness range. able to feel better, safety will increase. This project is being supported by the U.S. Figure 2 shows some experimental results, Medical Research and Material Command un- where an elastic rubber band was stretched us- Gudrun De Gersem, Jos Vander Sloten, der Grant #DAMD17-99-1-9022. ing a one-dimensional teleoperation system. and Hendrik Van Brussel The position-force curve shows a changing Department of Mechanical Engineering Craig Carignan, A. Pontus Olsson*, and slope, corresponding to a changing local stiff- Divisions PMA and BMGO Jonathan Tang† ness. Thereby, two major areas can be assigned. Katholieke Universiteit Leuven, Belgium Imaging Science and Information Systems At first, when the band is only slightly E-mail: (ISIS) Center stretched, a stiffness of about 220N/m is de- [email protected] Department of Radiology tected. Further stretched, the stiffness drops to Georgetown University Medical Center about 170N/m. The haptic device used shows References 1. R. Kumar, T. M. Goradia, A. C. Barnes, P. Jensen, Washington, DC, USA clear Coulomb friction, which adds damping, L. L. Whitcomb, D. Stoianovici, L. M. Auer, and E-mail: {crc32, †jt96}@georgetown.edu, but does not alter the local stiffness character- R. H. Taylor, Performance of Robotic Augmenta- *[email protected] istics. The fact that the slopes of the curves in tion in Microsurgery-Scale Motions, Springer- http://www.visualization.georgetown.edu/ the two areas differ more at the master side than Verlag Lecture Notes in Computer Science 1679, pp. 1108-1115, 1999. inmotion2.htm at the environment, shows how the stiffness dif- 2. S. E. Salcudean, S. Ku, and G. Bell, Performance ference between the two areas is ‘blown up’. Measurement in Scaled Teleoperation for References In fact, the difference is such that the areas eas- Microsurgery, Springer-Verlag Lecture Notes in 1. H. I. Krebs, N. Hogan, W. Hening, S. Adamovich, ily can be distinguished. This enhancement of Computer Science 1205, pp. 789-798, 1997. and H. Poizner, Procedural motor learning in discriminability between tissues could enable 3. G. De Gersem, H. Van Brussel, and F. Tendick, A parkinsons disease, Experimental Brain new optimisation function for force feedback in Research (141), p 425-437, 2001. surgeons to more securely define tumor bound- teleoperation, Proc. Int’l Conf. on Computer 2. C. R. Carignan and A. P. Olsson, Cooperative aries, and have a higher confidence on whether Assisted Radiology and Surgery (CARS), p. Control of Virtual Objects over the Internet using crucial structures in the neighborhood are clean 1354, 2003. Force-Reflecting Master Arms, Proc. IEEE Int’l Conf. on Robotics and Automation, pp. 1221- 1226, 2004. 3. G. Niemeyer and J. -J. Slotine, Towards force reflecting teleoperation over the internet, Proc. IEEE Int’l Conf. on Robotics and Automation, pp. 1909-1915, 1998. 4. I. Goncharenko, M. Svinin, S. Matsumoto, S. Hosoe, and Y.Kanou, Design and implementation of rehabilitation haptic simulators, Proc. Int’l Workshop on Virtual Rehabilitation, pp. 33-39, 2003.

Figure 2. Experimental results on the interaction with a rubber band: the environment (grey), and the positions and forces at the interface to the human operator (black). The slope of the position-force curves denotes the local stiffness.

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SPIE International Technical Group Newsletter 11 ROBOTICS AND MACHINE PERCEPTION 13.2 OCTOBER 2004

Enhanced haptic sensitivity in surgical telemanipulation

Robot-assisted minimally-inva- the tissue because the vein or sive surgery is a recent driving artery denotes a stiffer object field for research on haptic embedded in the soft fat. feedback within telemanipula- Also to define the boundaries tion. In minimally-invasive sur- of e.g. tumorous tissue within gery (MIS), long-shafted robot healthy tissue, stiffness dis- tools are inserted into the patient crimination is most impor- through small incisions, thereby tant. reducing trauma and recovery These examples, given by time. The use of a robot helps experienced surgeons, all can the surgeon to overcome tradi- be related to one requirement tional MIS drawbacks such as for a telesurgical system: the reduced dexterity and the non- human operator should be trivial hand-eye coordination able to discriminate between problem. In bilateral telemani- the stiffness of different (soft) pulation, the human operator tissues as well as within open manipulates a haptic interface surgery. through which the movements According to Weber, stiff- of the surgical robot holding the ness discrimination follows a tools can be controlled. The in- relative law.3 Only a slight terface offers the operator visual difference is necessary for and haptic information about the differentiating soft tissues, remote surgical scene. while more stiff objects need Traditionally, the perfor- to differ by a much greater mance of a telemanipulation amount in order to be distin- system is judged by its stabil- guishable by a human. This ity, its tracking behavior, and relative law suggests that, in the obtained transparency. In Figure 1. Block schematic for a one-dimensional teleoperation system with enhanced order to ameliorate discrimi- addition to these system capa- haptic sensitivity. The slave is under position control, and follows the master, with a native abilities through the bilities, we are interested in en- motion-scaling factor α if desired. At the haptic interface, adaptive impedance control is system by a factor σ, environ- hancing the haptic perceptual ment stiffness k should be implemented, using information about the environment stiffness ke and an offset force f0 e capabilities of the surgeon obtained by real-time estimation. transmitted to the operator in through the medical telerobot. an exponential relationship: σ This would allow the surgeon kt= K ke , with K being a con- to better discriminate between tissues than by Scaling techniques allow absolute human stant scaling factor. Naturally, this exponen- bare hand or direct manipulation. thresholds to be overcome: smaller forces can tial relationship cannot be obtained by using be perceived than with the bare hand, and mi- standard linear techniques. Absolute and relative sensitivity crometer-scale motions can be performed ac- The benefits of scaled telemanipulation for sur- curately. However, humans also have differ- Telemanipulation control for enhanced gical applications are clear. The robot can ex- ential thresholds. Even within the range where sensitivity tend human capabilities by allowing greater the human proprioceptive system is very sen- An extended Kalman filter estimates the en- spatial resolution in microsurgical tasks, reduc- sitive, a certain difference in stimuli needs to countered stiffness in real time. The control ing tremor, and significantly increasing pick be present in order for the human to be able to gains of the impedance controller of the haptic 1 and place accuracy. A study by Salcudean et distinguish between the two. interface are adapted to the online estimation 2 al. shows that using scaled-force feedback Within surgical procedures, surgeons specifi- of the environment stiffness (see Figure 1). yields better force-tracking behavior combined cally use their haptic senses to decide on a va- Mathematical manipulation allows for the with significantly less fatigue and a higher con- riety of problems. An artery or vein that is hid- fidence level. den beneath fat e.g., can be located by probing Continues on page 10.

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