Sensitive Skin
Vladimir J.Lumelsky,Fellow,IEEE,Michael S.Shur,Fellow,IEEE,and Sigurd Wagner,Fellow,IEEE
Abstract—Sensitive skin is a large-area,flexible array of nsors with data processing capabilities,which can be ud to cover the entire surface of a machine or even a part of a human body.Depending on the skin electronics,it endows its carrier with an ability to n its surroundings via the skin’s proximity,touch,pressure,temperature,chemical/biological,or other nsors.Sensitive skin devices will make possible the u of unsupervid machines operating in unstructured,unpredictable surroundings—among people,among many obstacles,outdoors on a crowded street,undera,or on faraway planets.Sensitive skin will make machines“cautious”and thus friendly to their environment.This will allow us to build machine helpers for the disabled and elderly,bring nsing to human prosthetics,and widen the scale of machines’u in rvice industry.With their ability to produce and process massive data flow,nsitive skin devices will make yet another advance in the information revolu-tion.This paper surveys the state of the art and rearch issues that need to be resolved in order to make nsitive skin a reality. The paper is partially bad on the report of the Sensitive Skin Workshop conducted jointly by the National Science Foundation (NSF)and Defen Advanced Rearch Projects Agency(DARPA) in October19
99in Arlington,V A,of which the three co-authors were the co-chairs[1].
Index Terms—Automation,electronics,large area nsor arrays, material science,robotics,nsing,nsitive skin.
I.I NTRODUCTION
I N THE famous Russian novel Master and Margarita by
gg是什么意思 Mikhail Bulgakov,one of the characters,a high-level Moscow bureaucrat,offends the Devil.For a swift and terrible punishment,he is banished from his suit,but his suit continues to sit at his desk,signing papers,barking commands,and generally functioning in the same way as its former wearer. This talking suit evokes the image of nsing and acting cloth—a bendable,stretchable skin with intelligent processing capabilities.Prent-day electronics technology does not allow us to produce such nsitive skin.Not yet.But the needs for it are big and increasing.And the necessary tools are at hand. Several novel technologies can be ud in order to fabricate
Manuscript received September8,2000;revid February27,2001.This work was largely bad on the report of the October’99NSF-DARPA Sensi-tive Skin Workshop.All Workshop participants contribute
d to the discussions on the issues around nsitive skins,and hence,to this text.The associate editor coordinating the review of this paper and approving it for publication was Prof. Mona Zaghloul.
V.J.Lumelsky is with the Department of Mechanical Engineering and the De-partment of Computer Sciences,University of Wisconsin,Madison,WI53706 USA(e-mail:lumelsky@engr.wisc.edu).
M.S.Shur is with the Center for Integrated Electronics and Electronics Manufacturing,Renslaer Polytechnic Institute,Troy,NY12180USA (e-mail:shurm@rpi.edu).
S.Wagner is with the Department of Electrical Engineering,Princeton Uni-versity,Princeton,NJ08544-0001USA(e-mail:wagner@princeton.edu). Publisher Item Identifier S1530-437X(01)04347-0.nsitive skin,and many novel ideas have already emerged. They will allow us to fulfill our dream for machines nsitive to their surroundings and operating in unstructured environment. This paper focus on the principles,methodology,and pro-totypes of nsitive skin-like devices,and the related system in-telligence and software that are necessary to make tho devices work.As discusd below,nsitive skin reprents a new par-adigm in nsing and control.The devices will open doors to a whole class of novel enabling technologies,with a potentially very wide impact.Far-reaching applications not feasible today will be realized,ranging from medicine and biology to the ma-chine industry and defen.
Some applications that nsitive skin devices will make possible are yet hard to foree.Flexible miconductor films and flexible metal interconnects that will result from this work will allow us to develop new inexpensive consumer electronics products,new types of displays,printers,new ways to store and share information(like electronic paper and“upgradeable”books and maps).New device concepts suitable for large area flexible miconductor films will lead to new nsors that will find applications in space exploration and defen,specifically in mine detection and active camouflage.
An ability of parallel processing of massive amounts of data from millions of nsors will find applications in environmental control and power industry.The areas will be further devel-oped becau of the highly interdisciplinary nature of the work on nsitive skin,which lies at the interction of information technology,mechanical engineering,material science,biotech-nology,and micro-and nanoelectronics.
Availability of nsitive skin hardware is likely to spur theo-retical and experimental work in many other disciplines that are far removed from robotics.This stimulus is comparable to that which triggered the explosion of control theory in the1940s and 1950s,in direct respon to the challenge pod by the appear-ance of fundamentally new hardware,such as jet fighters and radars.
To exemplify the concept of nsitive skin,a prototype of a nsitive skin module is shown in Fig.1.The module
contains
detector),each of which can n objects within a narrow cone at a distance up to about20cm.One of the most powerful abilities of the nsitive skin as applied to motion control is demonstrated in Fig.2.Here a skin-equipped robot arm manipulator dances with a ballerina. She does not hesitate to turn her back to the“partner,”fully ex-pecting a“human”reaction.Since every point of the robot body has its own nsing,no artifacts such as occlusions(a typical ,for vision devices)can interfere with the nsing.
情人节英文祝福语A block-diagram of the nsitive skin interconnects is shown in Fig.3.Fig.4illustrates some of the numerous potential applica-tions of nsitive skin envisioned by archers.
1530–437X/01$10.00©2001IEEE
Fig.1.Sensitive skin module:828=64infrared nsor pairs(LED’s and detectors);the distance between neighboring pairs is25mm;surface mounting technology;Kapton substrate.(V.Lumelsky,Robotics Laboratory,University of
Wisconsin-Madison.)
Fig.2.Ballerina dancing with a robot manipulator.As with two human partners,the whole dance is pre-reheard,but their actual positions at any given moment differ from one“performance”to the other.Since the robot’s nsitive skin allows it to continuously n the ballerina,she can trust her partner enough to turn her back to it and expect a“correct,”collision free reaction.(V. Lumelsky,Robotics Laboratory,University of Wisconsin-Madison.)
Some of the issues in the nsitive skin rearch are discusd below.After a general sweep in this Introduction of the ques-tions relevant to this area,the requirements to nsitive skin are considered in Section II,followed by a tentative list of disci-plines who development is expected to be affected by avail-ability of nsitive skin devices(Section III),and by the de-scription of specific technologies relevant to nsitive skin(Sec-tions IV–VIII).Section IX concludes the paper.Further details can be found in the Sensitive Skin Workshop Report[1].
A.Machines in Unstructured Environments
Imagine we want to design a home-helper machine for -nior citizens.We want this Helper to handle a modest range of tasks—pass a glass of juice,help the person to make a few steps, go to th
e door to let in a visitor.The machine should be powerful enough to support a walking person;it should have some kine-matics—let us say,an arm manipulator—to move things around.
Assume for a moment that the desired functions do not re-quire much intelligence—the person who will u the Helper is able to make decisions on what it should do and how.As-sume also that motion dexterity,such as in the human five-finger hand,is not necessary.We are willing to accept simple func-tionality,perhaps below the sophistication of modern industrial robots.In other words,the basic components necessary for our Helper—the drive system,nsors to e the object of a task, basic kinematics,and intelligence to execute tho tasks—do already largely exist.And yet,such a machine cannot be de-signed and built today—at any cost.
Why?Becau with today’s nsor technology,most of the Helper’s body surface would be left innsitive,unable to n most of clo-by objects.Sooner or later our Helper would topple over a shoe,crush a glass,step on a cat,clasp the person’s finger.To prevent this from happening,designers would have to significantly constrain the machine’s environ-ment.They must structure the environment.For example,they would require that the arrangement of objects in the room be fixed,that no unaccounted-for pets or socks appear at the scene,and that the person always sits in the same position when requesting the Helper’s rvices.Not surprisingly,this design would be unlike
ly to succeed.
The fundamental problem here is that our Helper must work in an unstructured environment—that is,a place that cannot be modified at will and thus has to be taken as is.An apartment is a good example of an unstructured environment.In contrast, the design and redesign of a structured environment,such as a factory floor,is only a matter of cost and efficiency.Today’s ma-chine automation is almost exclusively limited to the structured environment of the factory floor.The rest of the world,with per-haps99%of all tasks that involve motion and could in principle be automated,goes unautomated.Think of the unstructured en-vironments in agriculture,construction sites,offices,hospitals, etc.The majority of tasks that are of interest to us take place in unstructured environments,to which today’s automation simply cannot be applied.
Automated moving machines can be divided into unat-tended—tho that can operate without continuous supervision by a human operator,and mi-attended,which are controlled by the operator in a remote(teleoperated)fashion.Today the u of both types of machines is limited exclusively to highly structured environments—a factory floor,a nuclear reactor, a space telescope.Such machines can operate successfully with relatively little and fairly localized nsing.However, expensive resources are ud to compensate for the machines’inability to handle their environment.Today th
e“sanitized”environment of the factory floor is designed very precily and at high cost.This is true even for the so-called universal robot arm manipulators.The automotive industry pays,say,$70000 for a painting or welding arm manipulator,and then another $200000–$300000for a specially designed work cell to hou it.Many existing machines could,in principle,be uful in an unstructured environment,if not for the fact that they would endanger people,surrounding objects,and themlves.
The same is true for remotely controlled machines.Unless the work cell is“sanitized”into a structured environment,no -rious remote operation could be undertaken.Otherwi,at some
LUMELSKY et al.:SENSITIVE SKIN
43
Fig.3.Sketch of interconnects between nsors,intelligence,and
actuators.
Fig. 4.Potential applications of nsitive skin.(Courtesy of S.Ghaem,Motorola Advanced Technology Center.)
instant the operator will overlook a small or occluded object,and an unfortunate collision will occur.And so the designers take precautions,either by “sanitizing”the environment,or by enforcing maddeningly slow operation with endless stops and checks.Much of the associated extra expen would not be nec-essary if the machines had enough nsing to cope with unpre-dictable objects around them.
B.The Way Out is All-Encompassing Sensing
We emphasize again that today’s difficulty with making moving machines operate in our midst is not in the machine’s ability to perform the task.After all,very sophisticated tasks are done on today’s automated asmbly lines.The bottleneck is in the amount and density of nsing.When moving a glass of juice in a kitchen,any point of the machine’s body,not only its hand,may hit surrounding objects.Since in an unstructured environment tho objects cannot be anticipated,all-around nsing is the only way to know about them.
高二英语课文翻译Sensing that is needed is not,however,the nsing as we know it today.Supplying our home-helper w
因为是女子下载ith a few video cameras or a few dozens of tactile or sonar nsors distributed over its body or on the surrounding walls will not be enough.Sooner or later an object will obstruct the line of view of tho discrete localized nsors,and an impending collision will go undetected.It is precily for this reason humans and animals have some kind of nsing means at every point of their bodies.In the few known exceptions,an impenetrable shell,like in tur-tles,replaces nsing.To operate in an unstructured environ-ment,every point on the surface of a moving machine must be protected by this point’s “own”local nsing .
This sounds a bit counter-intuitive:why wouldn’t vision,or lar,or sonar,or other individual sophisticated nsors suffice?Think of humans and animals.Patients with lost skin nsitivity due to diabetes or burned skin are warned by their doctors that they cannot have normal life anymore and must be extra careful for a danger of inadvertently wounding themlves.It is known that people who lo nsitivity in the lower foot skin have dif-ficulty standing and walking.Or,that vering the nerve that pass touch information to the cat’s brain caus major changes in the animal’s gait and its handling of obstacles.Surprising as it may sound,while many blind people learn to have a productive life,a person with completely lost skin nsitivity is not likely to do so.Machines operating in unstructured environments face the same difficulties.Only the concept of a whole-surrounding nsitive skin can resolve the difficulties.
All-nsitive machine bodies are not a literary allegory or a whimsical sci-fi construct.If we want to move machine automa-tion beyond the factory floor,it is a bare necessity.The need for all-encompassing nsing for machines operating in unstruc-tured environments has been shown both theoretically and ex-perimentally.We happened to stumble upon a principle that is a necessary condition for existence of a large class of technology,and the one that the natural evolution discovered a long time ago.The lack of nsitive skins is the bottleneck in today’s ma-chine automation.
C.Sensitive Skin—A Universal Paradigm
Sensitive skin systems require a fundamental turnaround in design paradigm.Today the designer adds nsors to a machine as needed,analyzing carefully how many nsors are required and in which places.There is a good reason behind this ap-proach—individual nsors and their electronic control are rel-atively expensive;adding components decreas system relia-bility.This “poor man’s”design strategy hides significant costs.Even in cas where limited nsing might work,it may be cheaper and more reliable to u the universal and often even redundant nsitive skin,rather than go to an expensive custom design.
More than one nsor type may be necessary—proximity,touch,pressure,temperature,and chemical/biological nsing are a few examples.The functionality needed is quite generic,and so a few types of skin will cover a wide spectrum of ap-plications.We know such examples:the Intel’s Pentium micro-processor has much more functional power than any of us needs,but—being mass-produced,it becomes an economically viable solution in a huge number of applications,each of which could do with much less computing power.
44IEEE SENSORS JOURNAL,VOL.1,NO.1,JUNE2001
D.Impetus for Information Technology
Sensitive skin devices will include thousands and millions of elements that generate and process tremendous amounts of information,in parallel and in real time.This will hence be a new physical basis of information technology.With the eventual ubiquity of the nsing skin on various machinery,it is likely to bring the biggest leap in information technology hardware since the introduction of computers.In fact,the sheer amounts of information continuously generated and procesd by nsi-tive skin devices will make them challenge humans as predom-inant producers and urs of information.
straightlyE.Societal Needs and Concerns
1)Unstructured Machine Automation:Sensitive skins will reduce the need for low value-added rvices by vastly ex-panding the reach of automated machinery.They will bring the kind of productivity gains to rvice industries that integrated circuits have brought to manufacturing.Machines that by virtue of their size,power,and operation of their moving parts can prent danger to the surrounding objects or be damaged by them will be able to operate safely in their environment when equipped with the nsitive skin.For example,with the help of the nsitive skin covering its body,a mi-autonomous machine helper in a nior citizen’s hou or a robot probe in a deep space experiment will be carrying out its function without jeopardizing its own safety and that of the surrounding objects. No such machinery exists today.Automation for unstructured environments can completely transform the face of machine automation in the21st Century.
a)Health industry:Sensitive skin will supplant nsing ability of the human skin in limb prosthetics and as a replace-ment of damaged human skin.It will augment human nsing in wearable clothing,by monitoring,processing and wireless transfer of information about the well-being of the person wearing nsitive skin.This will advance the post-traumatic health care,care for disabled and elderly persons,and moni-toring of military personnel on the battlefield.
b)Environment-friendly technology:For the first time in history,machines will be endowed with a capacity to be careful. By its very nature,nsitive skin will contribute in a dramatic way to the reversal of the well-known negative impact of ma-chines on our environment,across a wide spectrum of natural and man-made ttings.We often hear about the role of com-puter revolution and office automation in the growth of economy and improved efficiency,which in turn affects the quality of life.Note the difference:while unstructured machine automa-tion will have a similar effect on the economy,its u in rvice industry will have a direct impact on the quality of human life. Biology and medical science thrive to prolong human life;the unstructured machine automation will constitute a systematic effort by engineers to improve the quality of life.
英语故事作文
c)Difficulties of acceptance:As with any fundamentally new and powerful technology,nsitive skin technology may evoke adver psychological reactions,with a potential of di-minishing its impact.Today we are psychologically unprepared for automatic moving machines operating in our midst.We are not sure we need them.We are uneasy about the idea of living side by side with a powerful unattended moving machine.It is difficult to imagine that one could stand next to a powerful moving machine and trust it enough to turn one’s back to it,or expect it to step aside when passing.Do we not have more than enough invasion of machinery in our lives?To need a very new pr
oduct,one must first experience it.Recall the skepticism about the Xerographic copier(even in the parent company)when this technology was just appearing—people were still unaware of the multiplicity of needs that easy copying could satisfy.
II.R EQUIREMENTS TO S ENSITIVE S KIN D EVICES
Four groups of rearch issues must be addresd in order to develop nsitive skin:Skin Materials,Sensing Devices,Signal and Data Processing,and Applications.Consider them one by one.
A.Skin Materials
Sensitive skin material(substrate)holds embedded nsors and related signal processing hardware.It needs to be flexible enough for attaching it to the outer surfaces of machines with moving parts and flexible joints.The skin must stretch,and de-sirably shrink and wrinkle the way human skin does,or to have other compensating features.Otherwi,machine parts may be-come“expod”as they move relative to each other.For ex-ample,Kapton®material,by the Dupont Corporation,can hold electronics,can bend,but cannot stretch.Stretching is especially challenging,as it may require materials that have never been ud in printed circuits.
乔布斯情书
Wiring must keep its integrity when nsitive skin is stretched or wrinkled.This requirement calls for novel wire materials, e.g.,conductive elastomers or vesls carrying conductive liquid,or novel ways of wire design with traditional materials, such as helical,stretchable wires.
Still another possibility is miconducting textiles,a tech-nology that will find applications in wearable computing and wearable electronics.The efforts in developing such materials are now under way at veral universities and veral compa-nies,including NCSU,IBM,Phillips,BIT’s,Inc.,and Printed Transistors,Inc.
B.Sensing Devices
Sensitive skin components have to be deployed in two-dimen-sional(2-D)or even quasi-three-dimensional(3-D),layered)ar-rays of sufficiently high density.A reprentative model would be a piece of skin of
1,with nsors spread uniformly at a pitch of
1
LUMELSKY et al.:SENSITIVE SKIN45 including proximity or tactile,discrete or continuous,are
acceptable.Sensor arrays with special or unique properties are
of much interest,for example a cleanable and washable skin
for“dirty”tasks in nuclear/chemical waste site applications;
radiation-hardened skin for nuclear reactor and space appli-
南回归线英文
cations;and skins that can smell,taste,or react to ambient
light.The ability to measure distance to objects would be a
great advantage for enabling dexterous motion of the machine
equipped with the skin.
For lf-diagnosis and reliability,“lf-nsing”ability of the
skin is highly desirable;this may include nsing of contami-
nation,dust,chemical substances,temperature,radiation on its
surface,as also detection of failure of individual skin nsors
and an ability to work around failed areas.intent
No existing types of nsors are likely to satisfy all require-
ments.For example,a light nsor is fast and accurate;sonar
and capacitance nsors require less power but have poor reso-
lution.Conquently,new nsors,or new combinations of ex-
isting nsors,or new ways of packaging existing nsors may
be developed to satisfy the needs.
C.Signal/Data Processing
To produce continuous motion,the sampling rates of today’s
北京韩语学习班typical computer-controlled moving machines should be in the
range of30–50Hz.Taking50Hz as an example,within the
available20ms sampling period all skin nsors must be polled,
information from tho nsors that n objects pasd to the
machine control and analyzed,and motion commands for the
next step nt to the drive motors and executed.With possibly
millions of nsors per1m
