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`PROVISIONAL APPLICATION FOR PATENT COVER SHEET
`co'° ==o
`This is a request for filing a PROVISIONAL APPLICATION FOR PATENT under 37 CFR 1 53(c)
`
`l l
`
`Given Name (first and middle [if any])
`
`Family Name or Surname
`
`Residence
`ICitv and either State or Foreian Country}
`
`INVENTOR(S}
`
`Joseph L.
`
`Jones
`
`Acton, MA
`
`D Additional inventors are being named on the _
`TITLE OF THE INVENTION 1280 characters max\
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`separately numbered sheets attached hereto
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`Multi-Mode Coverage for an Autonomous Robot
`D Customer Number I
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`
`Twin City Office Center, Suite 6
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`22 McGrath Highway
`
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`USA
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`MA
`617.629.0055
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`Applicant claims small entity status. See 37 CFR 1.27.
`A check or money order is enclosed to cover the filing fees
`
`I 501806
`
`I
`
`Respectfully submitt/,A
`l / .'
`TYPED or PRINTED NAME Glen D. Weinstein
`
`SIGNATURE
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`//J~/(___
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`Date \6112.1011
`REGISTRATION NO.
`(If appropnate)
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`IROBOT 2004
`Shenzhen Zhiyi Technology v. iRobot
`IPR2017-02061
`
`

`

`r
`
`In the United States Patent and Trademark Office
`
`Mailed: June 12, 2001
`
`Box Provisional Patent Application
`Assistant Commissioner for Patents
`Washington, District of Columbia 20231
`
`Title:
`Inventor:
`Assignee:
`Filing Date:
`
`MULTI-MODE COVERAGE FOR AN AUTONOMOUS ROBOT
`Joseph L. Jones
`iRobot Corporation
`June 12, 2001
`
`Sir:
`
`Please file the following enclosed Provisional Patent Application (PPA) papers listed below
`under 37 C.F.R. § 1.53(b)(2).
`
`1.
`2.
`3.
`4.
`5.
`6.
`7.
`
`Provisional Application for Patent Cover Sheet (1 page)
`Specification (22 pages)
`Drawings (9 pages, informal)
`Small Entity Statement (1 page)
`Fee Transmittal (2 Copies)
`Return Receipt Postcard Addressed to Assignee
`Declaration of Mailing by "EXPRESS MAIL"
`
`Very respectfully,
`
`eeinstein
`
`Reg. No. 43,981
`
`Express Mail Label # EK518595065US
`Date of Deposit: June 12, 2001
`
`2
`
`

`

`PTO/SB/17 (11-00)
`Approved for use through 10/31/2002. OMB 0651-0032
`U.S Patent and Trademark Office; U.S. DEPARTMENT OF COMMERCE
`I Inner th<> p~n°rwnrk R<>rluction Ar.t nf 1995 no oersons are reauired to r>cnond to a r.o/IP.r.trnn of inform~tinn unlocc it disnl<>"c ~ v~liri OMB r.ontrol number.
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`Complete if Known
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`FEE TRANSMITTAL
`for FY 2001
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`Patent fees are subject to annual revision.
`
`Aoolication Number
`
`Filing Date
`
`First Named Inventor
`
`Examiner Name
`
`Group Art Unit
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`\...TOTAL AMOUNT OF PAYMENT
`
`I($) 75_00
`
`Attorney Docket No.
`
`DP-5
`
`METHOD OF PAYMENT
`
`The Commissioner is hereby authorized to charge
`J:71
`1. i!'.'.'..J
`indicated fees and credit any overpayments to:
`I
`~~di
`501806
`Account
`Number
`Deposit ~I===============:::::!!
`iRobot Corporation
`
`Account
`Name
`
`.
`
`.
`
`.
`
`Charge Any Addrtronal Fee Requrred
`Under 37 CFR 1.16 and 1 17
`Applicant clarms small entrty status
`See 37 CFR 1.27
`
`Payment Enclosed:
`
`Check D Credit card D Money
`
`Order
`
`2. D
`D
`
`FEE CALCULATION
`1. BASIC FILING FEE
`Large Entity Small Entity
`Fee Fee Fee Fee
`Fee Description
`Code ($) Code ($)
`101 710
`201 355 Utility filing fee
`206 160 Design filing fee
`207 245 Plant filing fee
`208 355 Reissue filing fee
`
`106 320
`107 490
`108 710
`
`114 150
`
`214
`
`75 Provisional filing fee
`
`D Other
`
`Fee Paid
`
`SUBTOTAL (1) I($) 75.00
`
`FEE CALCULATION (continued)
`3. ADDITIONAL FEES
`Large
`Small
`Entity
`Entity
`Fee Fee
`Fee
`Fee
`Code ($) Code ($)
`
`· t"
`F D
`ee escnp ion
`
`105 130 205
`
`65 Surcharge - late filing fee or oath
`
`127
`
`50
`
`227
`
`25 Surcharge - late provisional filing fee or
`cover sheet
`
`139 130
`
`139 130 Non-English specrfication
`
`Fee Paid
`
`147 2,520
`
`112 920*
`
`113 1,840*
`
`115 110
`116 390
`117 890
`
`215
`55
`216 195
`217 445
`
`147 2,520 For filing a request for ex parte reexaminatror
`112 920* Requesting publication of SIR prior to
`Examiner actron
`113 1,840* Requesting publication of SIR after
`Examiner actron
`Extension for reply within first month
`
`Extension for reply within second month
`Extension for reply w1thrn third month
`
`118 1,390
`
`218 695
`
`Extension for reply within fourth month
`
`128 1,890
`
`228 945
`
`Extension for reply within fifth month
`
`119 310
`
`219 155
`
`Notice of Appeal
`
`120 310
`
`220 155
`
`121 270
`138 1,510
`
`221 135
`138 1,510
`
`Filing a brief in support of an appeal
`Request for oral hearing
`Petition to institute a public use proceeding
`
`240
`
`2. EXTRA CLAIM FEES
`
`Total Claims
`Independent
`Claims
`Multiple Dependent
`
`Fee from
`Extra Claims ~ Fee Paid
`C=:J -20·· = ~ x L___J =I
`I
`D
`-3·· = C=:J x i==:J =I
`I
`c::=J=l
`I
`
`Large Entity Small Entity
`Fee Fee Fee Fee
`Code($) Code ($)
`103
`18
`203
`9
`
`Fee Description
`
`Claims in excess of 20
`
`140 110
`
`55
`
`Petition to revive - unavoidable
`
`141 1,240
`142 1,240
`143 440
`
`241 620
`242 620
`243 220
`
`144 600
`
`122 130
`
`244 300
`122 130
`
`Petition to revive - unintentional
`Utility issue fee (or reissue)
`Design issue fee
`Plant issue fee
`
`Petitions to the Commissioner
`
`123
`
`50
`
`123
`
`50
`
`Processing fee under 37 CFR 1. 17( q)
`
`126 180
`
`126 180
`
`Submission of Information Disclosure Stmt
`
`581
`
`40
`
`581
`
`40
`
`Recording each patent assignment per
`property (times number of properties)
`
`102
`
`80
`
`202 40
`
`Independent claims in excess of 3
`
`146 710
`
`246 355
`
`104 270
`
`204 135
`
`Multiple dependent claim, if not paid
`
`109
`
`80
`
`209 40
`
`110
`
`18
`
`210
`
`9
`
`•• Reissue independent claims
`over original patent
`
`.. Reissue claims in excess of 20
`and over original patent
`
`SUBTOTAL (2)
`
`*"or number previously paid, if greater; For Reissues, see above
`
`SUBMITTED BY
`
`Name (Pnnt/Type)
`
`Signature
`
`Glen D. Weinstein
`
`149 710
`
`249 355
`
`Filing a submission after final rejection
`(37 CFR § 1 129(a))
`For each additional invention to be
`examined (37 CFR § 1.129(b))
`
`179 710 279 355 Request for Continued Examination (RCE)
`
`169 900 169 900 Request for expedited examination
`of a design appl1cat1on
`Other fee (specify) -----·-----------------------------;==----======l
`I
`SUBTOTAL (3) le$)
`
`*Reduced by Basic Filing Fee Paid
`
`43,981
`
`Complete (If app/1cable)
`
`Telephone t{i r 6U 00 '.fT
`
`Date
`
`NING: Information on this form may become public. Credit card information should not
`be included on this form. Provide credit card information and authorization on PT0-2038.
`Burden Hour Statement: This form is estimated to take 0.2 hours to complete Time will vary depending upon the needs of the individual case Any comments on
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`20231. DO NOT SEND FEES OR COMPLETED FORMS TO THIS ADDRESS SEND TO: Assrstant Commissioner for Patents, Washington, DC 20231.
`
`3
`
`

`

`In the United States Patent and Trademark Office
`
`Box Provisional Patent Application
`Assistant Commissioner for Patents
`Washington, District of Columbia 20231
`
`Title:
`Inventor:
`Assignee:
`Filing Date:
`
`Multi-Mode Coverage for an Autonomous Robot
`Joseph L. Jones
`iRobot Corporation
`June 12, 2001
`
`DECLARATION OF MAILING BY "EXPRESS MAIL"
`
`Glen D. Weinstein declares as follows:
`
`1. I reside at 675 Grove Street, Newton, MA 02462, and am an employee of iRobot
`Corporation, Twin City Office Center, Suite 6, 22 McGrath Highway, Somerville,
`MA 02143.
`
`2. On June 12, 2001, I deposited in the mail, "Express Mail Post Office to Addressee"
`service of the United States Postal Service the contents of the envelope for which
`"Express Mail" receipt No. EK518595065US was issued addressed to: Box
`Provisional Application, Assistant Commissioner for Patents, Washington, D.C.,
`20231.
`
`3. I hereby declare that all statements made herein of my own knowledge are true and
`that all statements made on information and belief are believed to be true; and further
`that these statements were made with the knowledge that willful false statements and
`the like so made are punishable by fine or imprisonment, or both, under Section 1001
`of Title 18 of the United States Code and that such willful false statements may
`jeopardize the validity of the above-identified application or any patents issued
`thereon.
`
`Very respectfully,
`
`?ti
`
`Glen D. Weinstein
`Reg. No. 43,981
`
`Express Mail Label # EK518595065US
`Date of Deposit: June 12, 2001
`
`4
`
`

`

`Patent Application of
`
`Joseph L. Jones
`
`for
`
`MULTI-MODE COVERAGE FORAN AUTONOMOUS ROBOT
`
`5
`
`This application is entitled to the benefit of United States Provisional Application
`
`Ser. No. 60/237,255 filed October 2, 2000.
`
`FIELD OF THE INVENTION
`
`10
`
`This invention relates generally to autonomous vehicles or robots, and more
`
`specifically to methods and mobile robotic devices for covering a specific area as might
`
`be required of, or used as, robotic cleaners or lawn mowers.
`
`DESCRIPTION OF PRIOR ART
`
`15
`
`For purposes of this description, examples will focus on the problems faced in the
`
`prior art as related to robotic cleaning (~, dusting, buffing, sweeping, scrubbing, dry
`
`mopping or vacuuming). The claimed invention, however, is limited only by the claims
`
`themselves, and one of skill in the art will recognize the myriad of uses for the present
`
`invention beyond indoor, domestic cleaning.
`
`20
`
`Robotic engineers have long worked on developing an effective method of
`
`autonomous cleaning. By way of introduction, the performance of cleaning robots should
`
`concentrate on three measures of success: coverage, cleaning rate and perceived
`
`effectiveness. Coverage is the percentage of the available space visited by the robot
`
`DP-5
`Filed June 12, 2001
`
`1
`
`5
`
`

`

`during a fixed cleaning time, and ideally, a robot cleaner would provide 100 percent
`
`coverage given an infinite run time. Unfortunately, designs in the prior art often leave
`
`portions of the area uncovered regardless of the amount of time the device is allowed to
`
`complete its tasks. Failure to achieve complete coverage can result from mechanical
`
`5
`
`limitations - ~, the size and shape of the robot may prevent it from reaching certain
`
`areas. Failure to achieve complete coverage can also result from an inadequate coverage
`
`algorithm. The coverage algorithm is the set of instructions used by the robot to control
`
`its movement. For the purposes of the present invention, coverage is discussed as a
`
`percentage of the available area visited by the robot during a finite cleaning time. Due to
`
`10 mechanical and/or algorithmic limitations, certain areas within the available space may
`
`be systematically neglected. Such systematic neglect is a significant limitation in the
`
`prior art.
`
`A second measure of a cleaning robot's performance is the cleaning rate given in
`
`units of area cleaned per unit time. Cleaning rate refers to the rate at which the area of
`
`15
`
`cleaned floor increases. Coverage rate refers to the rate at which the robot covers the
`
`floor regardless of whether the floor was previously clean or dirty. If the velocity of the
`
`robot is v and the width of the robot's cleaning mechanism is w then the robot's coverage
`
`rate is simply wv.
`
`20
`
`A robot that moves in a purely randomly fashion in a closed environment has a
`
`cleaning rate that decreases relative to the robot's coverage rate as a function of time.
`
`This is because the longer the robot operates the more likely it is to revisit already
`
`cleaned areas. The optimal design has a cleaning rate equivalent to the coverage rate, thus
`
`minimizing unnecessary repeated cleanings of the same spot. In other words, the ratio of
`2
`
`DP-5
`Filed June 12, 2001
`
`6
`
`

`

`cleaning rate to coverage rate is a measure of efficiency and an optimal cleaning rate
`
`would mean coverage of the greatest percentage of the designated area with the minimum
`
`number of cumulative or redundant passes over an area already cleaned.
`
`A third metric of cleaning robot performance is the perceived effectiveness of the
`
`5
`
`robot. This measure is ignored in the prior art. Deliberate movement and certain
`
`patterned movement is favored as users will perceive a robot that contains deliberate
`
`movement as more effective.
`
`While coverage, cleaning rate and perceived effectiveness are the performance
`
`criteria discussed herein, the preferred embodiment of the present invention also takes
`
`10
`
`into account the ease of use in rooms of a variety of shapes and sizes (containing a
`
`variety of unknown obstacles) and the cost of the robotic components. Other design
`
`criteria may also influence the design, for example the need for collision and appropriate
`
`response to other hazards.
`
`As described in detail in Jones, Flynn & Seiger, Mobile Robots: Inspiration to
`
`15
`
`Implementation second edition, 1999, AK Peters, Ltd., and elsewhere, numerous
`
`attempts have been made to build vacuuming and cleaning robots. Each of these robots
`
`has faced a similar challenge: how to efficiently cover the designated area given limited
`
`energy reserves.
`
`We refer to maximally efficient cleaning, where the cleaning rate equals the coverage
`
`20
`
`rate, as deterministic cleaning. As shown in FIG. OA, a robot following a deterministic
`
`path moves in such a way as to completely cover the area while avoiding all redundant
`
`cleaning. Deterministic cleaning requires that the robot know both where it is and where
`
`it has been; this in turn requires a positioning system. Such a positioning system (a
`
`DP-5
`Filed June 12, 2001
`
`3
`
`7
`
`

`

`positioning system suitably accurate to enable deterministic cleaning might rely on
`
`scanning laser rangers, ultrasonic transducers, carrier phase differential GPS, or other
`
`method) can be prohibitively expensive and involve user set-up specific to the particular
`
`room geometries. Also, methods that rely on global positioning are typically
`
`5
`
`incapacitated by the failure of any part of the positioning system.
`
`One example of using highly sophisticated (and expensive) sensor technologies to
`
`create deterministic cleaning is the RoboScrub device built by Denning Mobile Robotics
`
`and Windsor Industries, which used sonar, infrared detectors, bump sensors and high-
`
`precision laser navigation. RoboScrub's navigation system required attaching large bar
`
`10
`
`code targets at various positions in the room. The requirement that RoboScrub be able to
`
`see at least four targets simultaneously was a significant operational problem.
`
`RoboScrub, therefore, was limited to cleaning large open areas.
`
`Another example, RoboKent, a robot built by the Kent Corporation, follows a
`
`global positioning strategy similar to RobotScrub. RoboKent dispenses with
`
`15
`
`RobotScrub's more expensive laser positioning system but having done so RoboKent
`
`must restrict itself only to areas with a simple rectangular geometry, e.g. long hallways.
`
`In these more constrained regions position correction by sonar ranging measurements is
`
`sufficient.
`
`Because of the limitations and difficulties of deterministic cleaning, some robots
`
`20
`
`have relied on pseudo-deterministic schemes. One method of providing pseudo-
`
`deterministic cleaning is an autonomous navigation method known as dead reckoning.
`
`Dead reckoning consists of measuring the precise rotation of each robot drive wheel
`
`(using for example optical shaft encoders). The robot can then calculate its expected
`
`DP-5
`Filed June 12, 2001
`
`4
`
`8
`
`

`

`position in the environment given a known starting point and orientation. One problem
`
`with this technique is wheel slippage. If slippage occurs, the encoder on that wheel
`
`registers a wheel rotation even though that wheel is not driving the robot relative to the
`
`ground. As shown in FIG. OB, as the robot navigates about the room these drive wheel
`
`5
`
`slippage errors accumulate making this type of system unreliable for runs of any
`
`substantial duration. The result of reliance on dead reckoning is intractable systematic
`
`neglect; in other words, areas of the floor are not cleaned.
`
`One example of a pseudo-deterministic a system is the Cye robot from Probotics,
`
`Inc. Cye depends exclusively on dead reckoning and therefore takes heroic measures to
`
`10 maximize the performance of its dead reckoning system. Cye must begin at a user-
`
`installed physical registration spot in a known location where the robot fixes its position
`
`and orientation. Cye then keeps track of position as it moves away from that spot. As
`
`Cye moves uncertainty in its position and orientation increase. Cye must make certain to
`
`return a calibration spot before this error grows so large that it will be unlikely to locate a
`
`15
`
`calibration spot. If a calibration spot is moved or blocked or if excessive wheel slippage
`
`occurs then Cye can become lost (possibly without realizing that it is lost). Thus Cye is
`
`suitable for use only in relatively small benign environments.
`
`20
`
`Another approach to robotic cleaning is purely random motion. As shown in FIG.
`
`OC, in a typical room without obstacles, a random movement algorithm will provide
`
`acceptable coverage given significant cleaning time. Compared to a robot with a
`
`deterministic algorithm, a random cleaning robot must operate for a longer time to
`
`achieve good coverage. To have high confidence that the random-motion robot has
`5
`
`DP-5
`Filed June I 2, 200 I
`
`9
`
`

`

`cleaned 98% of an obstacle-free room we must allow the random motion robot to run
`
`approximately five times as long as a deterministic robot with the same cleaning
`
`mechanism moving at the same speed.
`
`The coverage limitations of a random algorithm can be seen in FIG. OD.
`
`5 Obstacles in the room can create the effect of segmenting the room into a series of
`
`chambers. The coverage over time of a random algorithm robot in such a room is
`
`analogous to the time density of gas released in one chamber of a confined volume.
`
`Initially, the density of gas is highest in the chamber where it is released and lowest in
`
`more distant chambers. Similarly the robot is most likely to thoroughly clean the
`
`10
`
`chamber where it starts, rather than more distant chambers, early in the process. Given
`
`enough time a gas reaches equilibrium with equal density in all chambers. Likewise
`
`given time, the robot would clean all chambers thoroughly. The limitations of practical
`
`power supplies, however, usually guarantee that the robot will have insufficient time to
`
`clean all areas of a space cluttered with obstacles. We refer to this phenomenon as the
`
`15
`
`robot diffusion problem.
`
`As discussed, the commercially available prior art has not been able to produce an
`
`effective coverage algorithm for an area of unknown geometry. As noted above, the prior
`
`art either has relied on sophisticated systems of markers or beacons or has limited the
`
`utility of the robot to rooms with simple rectangular geometries. Attempts to use pseudo-
`
`20
`
`deterministic control algorithms can leave areas of the space systematically neglected.
`
`OBJECTS AND ADV ANT AGES
`
`[TO BE MODELED AFTER FINAL CLAIMS]
`
`DP-5
`Filed June 12, 2001
`
`6
`
`10
`
`

`

`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 - Overview of Robot's basic components (incl. Optional section device)
`
`FIG. 2-Diagram showing orientation of control system
`
`FIG. 3 - schematic of operational modes
`
`5
`
`FIG. 4 - diagram of spot cleaning movement
`
`FIG. 5 - spot cleaning algorithm of proffered embodiment
`
`FIG. 6 -- diagram of edge cleaning movement
`
`FIG. 7 - edge following algorithm of preferred embodiment
`
`FIG. 8 - diagram of room cleaning movement
`
`10
`
`FIG. 9 - room cleaning algorithm of preferred embodiment
`
`FIG 10 graph movement example of single and dual modes
`
`FIG. 11 graph movement of the preferred embodiment
`
`DESCRIPTION OF INVENTION
`
`In the present invention, a mobile robot is designed to provide maximum
`
`15
`
`coverage at an effective cleaning rate in a room of unknown geometry. In addition, the
`
`perceived effectiveness of the robot is enhanced by the inclusion of patterned or
`
`deliberate motion.
`
`While the physical structures of mobile robots are known in the art, the
`
`components of the preferred embodiment of the present invention is described herein.
`
`20
`
`The preferred embodiment of the present invention is a substantially circular robotic
`
`sweeper containing certain features. As shown in FIG. 1, for example, the mobile robot
`
`10 of the preferred embodiment includes a chassis 11 supporting mechanical and
`
`electrical components. These components include various sensors, including two bump
`
`DP-5
`Filed June 12, 2001
`
`7
`
`11
`
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`sensors 12 & 13 located in the forward portion of the robot, four cliff sensors 14 located
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`on the robot shell 15, and a wall following sensor 16 mounted on the robot shell 15. In
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`other embodiments, as few as one sensor may be used in the robot. One of skill in the art
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`will recognize that the sensor(s) may be of a variety of types including sonar, tactile,
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`electromagnetic, etc. Because of cost restraints, the preferred embodiment of the present
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`invention uses bump (tactile) sensors and reflective IR proximity sensors for the cliff
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`sensors 14 and the wall-following sensor 16.
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`The preferred embodiment of the robot also contains two wheels 20, motors 21
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`for driving the wheels independently, an inexpensive low-end microcontroller 22, and a
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`10
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`rechargeable battery 23 or other power source known in the art. These components are
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`well known in the art and are not discussed herein. The robotic cleaning device 10
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`further includes a cleaning head 30. The cleaning head might contain a vacuum cleaner,
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`various brushes, sponges, mops, electrostatic cloths or a combination of various cleaning
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`elements.
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`15
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`As mentioned above, the preferred embodiment of the robotic cleaning device 10
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`comprises an outer shell 15 defining a dominant side, non-dominant side, and a front
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`portion of the robot 10. The dominant side of the robot is the side that is kept near or in
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`contact with an object when the robot cleans the area adjacent to that object. In the
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`preferred embodiment, as shown in FIG. 1, the dominant side of the robot 10 is the right-
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`hand side relative to the primary direction of travel, although in other embodiments the
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`dominant side may be the left-hand side. The primary direction of travel is as shown in
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`FIG .1 by arrow 40.
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`In the preferred embodiment, two bump sensors 12 & 13 are located forward of
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`the wheels 20 relative to the direction of forward movement, shown by arrow 40. One
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`bump sensor 13 is located on the dominant side of the robot 10 and the other bump sensor
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`12 is located on the non-dominant side of the robot 10. When both of these bump sensors
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`12 & 13 are activated simultaneously, the robot 10 recognizes an obstacle in the front
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`position. In other embodiments, more or fewer individual bump sensors can be used.
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`Likewise, any number of bump sensors can be used to divide the device into any number
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`of radial segments. While in the preferred embodiment the bump sensors 12 & 13 are IR
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`break beam sensors activated by contact between the robot 10 and an obstacle. Other
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`types of sensors can be used.
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`The preferred embodiment also contains a wall-following or wall-detecting sensor
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`16 mounted on the dominant side of the robot 10. In the preferred embodiment, the wall
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`following sensor is an IR sensor composed of an emitter and detector pair collimated so
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`that a finite volume of intersection occurs at the expected position of the wall. This focus
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`point is approximately three inches ahead of the drive wheel in the direction of robot
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`forward motion. The radial range or wall detection is about 0.75 inches.
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`The preferred embodiment also contains any number of IR cliff sensors 14 that
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`prevent the device from tumbling over stairs or other vertical drops. These cliff sensors
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`are of a construction similar to that of the wall following sensor but directed to observe
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`the floor rather than a wall.
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`Other embodiments may use other known sensors or combinations of sensors.
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`For purposes of understanding the movement of the robotic device, FIG. 2 shows
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`the orientation of the robot 10 centered about the x and y axes in a coordinate plane; this
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`coordinate system is attached to the robot. The directional movement of the robot 10 can
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`be understood to be the radius at which the robot 10 will move. In order to rapidly tum
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`away from the wall I 00, the robot 10 should set a positive, small value of r (r3 in FIG.2);
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`in order to rapidly tum toward the wall, the robot should set a negative, small value of r
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`(r1 in FIG.2). On the other hand, to make slight turns, the robot should set larger absolute
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`values for r positive values to move left (i.e. away from the wall, r4 in FIG.2) and
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`negative values to move right (i.e. toward the wall, (r2 in FIG.2). This coordinate scheme
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`is used in the examples of control discussed below. The microcontroller 22 controlling
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`differential speed at which the individual wheel motors 21 are run, determines the turning
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`radius.
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`FIG. 3 shows a simple block representation of the various operational modes of
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`the cleaning device. In the preferred embodiment, and by way of example only,
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`operational modes may include spot cleaning (where the user designates a specific region
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`for cleaning), edge cleaning, and room cleaning. Each operational mode comprises
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`complex combinations of internal behaviors. These complexities, however, are hidden
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`from the user. In one embodiment, the user can select the particular operational mode by
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`using an input element, for example, a selector switch or push button. In other preferred
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`embodiments, as described below, the robot is able to autonomously cycle through the
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`operational modes.
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`FIGS. 4-11 show the details of each of the preferred operational modes.
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`Spot Cleaning
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`Spot cleaning allows the user to clean an isolated dirty area. The user places the
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`robot 10 on the floor near the center of the area that requires cleaning and selects the
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`spot-cleaning operational mode. The robot then moves in such a way that the immediate
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`area within, for example, a defined radius, is brought into contact with the cleaning head
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`30 or side brush [ADD SIDE BRUSH ON DRAWING] of the robot.
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`One method of achieving spot cleaning is a control algorithm providing outward
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`spiral movement, as shown in FIG. 4A. In general, spiral movement is generated by
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`increasing the turning radius as a function of time. In the preferred embodiment, the
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`robot 10 begins its spiral in a counter-clockwise direction, marked in FIG. 4A by
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`10 movement line 45, in order to keep the dominant side on the outward, leading-edge of the
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`spiral. In another embodiment, shown in FIG. 4B, spiral movement of the robot 10 is
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`generated inward such that the radius of the turns continues to decrease. The inward
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`spiral is shown as movement line 45 in FIG. 4B. It is not necessary, however, to keep the
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`dominant side of the robot on the outside during spiral motion.
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`The method of spot cleaning used in the preferred embodiment - outward
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`spiraling- is set forth in FIG.5. Once the spiraling is initiated (step 201) and the value of
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`r is set at its minimum, positive value (which will produce the tightest possible
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`counterclockwise tum), the spiraling behavior recalculates the value ofr as a function of
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`? , where ? represents the angular turning since the initiation of the spiraling behavior
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`20
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`(step 210). By using the equation r =a?, where a is a constant coefficient, the tightness or
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`desired overlap of the spiral can controlled. The value of a can be chosen by the equation
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`a= f p; where dis the distance between two spirals. For effective cleaning, a value ford
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`should be chosen that is less than the width of the cleaning mechanism 30. In the
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`preferred embodiment, a value of d is selected that is two-thirds of the width of the
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`cleaning head 30.
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`In spiral mode, various actions can be taken when an obstacle is encountered. For
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`example, the robot could (a) seek to avoid the obstacle and continue the spiral in the
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`counter-clockwise direction, (b) seek to avoid the obstacle and continue the spiral in the
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`opposite direction (e.g. changing from counter-clockwise to clockwise), or ( c) change
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`operational modes. Continuing the spiral in the opposite direction is known as reflective
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`spiraling and is represented in FIG. 4C, where the robot 10 reverses its movement path 45
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`when it comes into contact with obstacle 101. In the preferred embodiment, as detailed
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`in step 220, the robot 10 exits spot cleaning mode upon the first obstacle encountered by
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`a bump sensor 12 or 13.
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`Wall Following/Edge Cleaning
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`Edge cleaning allows the user to clean only the edges of a room or the edges of
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`objects within a room. The user places the robot 10 on the floor near an edge to be
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`cleaned and selects the edge-cleaning operational mode. The robot 10 then moves in
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`such a way that it follows the edge and cleans all areas brought into contact with the
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`cleaning head 30 of the robot.
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`The movement of the robot 10 in a room 110 is shown in FIG. 6. In FIG. 6A, the
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`robot 10 is placed along with wall 100, with the robot's dominant side next to the wall.
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`The robot then runs along the wall indefinitely following movement path 46. Similarly,
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`in FIG. 6B, the robot 10 is placed in the proximity of an obstacle 101. The robot then
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`follows the edge of the obstacle 110 indefinitely following movement path 47.
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`DP-5
`Filed June 12, 2001
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`In the preferred embodiment, in the wall-following mode, the robot uses the wall-
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`following sensor 16 to position itself a set distance from the wall. The robot then
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`proceeds to travel along the perimeter of the wall. As shown in FIGS. 6A & 6B, in the
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`preferred embodiment, the robot 10 is not able to distinguish between a wall 100 and
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`another solid obstacle 101.
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`The method used in the preferred embodiment for following the wall is detailed in
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`FIG. 7 and provides a smooth wall following operation even with a one-bit sensor. (Here
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`the one