`INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`WO 00/38026
`
`(51) International Patent Classification 7 :
`GOSD 1/02
`
`(11) International Publication Number:
`
`Al
`
`(43) International Publication Date:
`
`29 June 2000 (29.06.00)
`
`WORLD INTELLECTUAL PROPERTY ORGANIZATION
`International Bureau
`
`(21) International Application Number:
`
`PCT/GB99/04090
`
`(22) International Filing Date:
`
`6 December 1999 (06.12.99)
`
`(30) Priority Data:
`9827758.5
`
`18 December 1998 (18.12.98) GB
`
`(71) Applicant (for all designated States except US): NOTETRY
`LIMITED [GB/GB]; Kingsmead Mill, Little Somerford,
`Wiltshire SN15 5JN (GB).
`
`(72) Inventors; and
`(75) Inventors/Applicants (for US only): BISSET, David, Lindsey
`[GB/GB]; 4 Chandler Way, Chippenham, Wiltshire SN15
`3YG (GB). CLARK, Alan, Gerard [GB/GB]; 3 Grange
`Cottages, Grange Lane, Malmesbury, Wiltshire SN16 OEP
`(GB).
`
`(74) Agents: SMITH, Gillian, Ruth et al.; Dyson Research Limited,
`P.O. Box 2080, Malmesbury, Wiltshire SN16 OSW (GB).
`
`(81) Designated States: AE, AL, AM, AT, AU, AZ, BA, BB, BG,
`BR, BY, CA, CH, CN, CR, CU, CZ, DE, DK, DM, EE,
`ES, Fl, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP,
`KE,KG,KP,KR,KZ,LC,LK,LR,LS,LT,LU,LV,MA,
`MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU,
`SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, TZ, UA, UG,
`US, UZ, VN, YU, ZA, ZW, ARIPO patent (GH, GM, KE,
`LS, MW, SD, SL, SZ, TZ, UG, ZW), Eurasian patent (AM,
`AZ, BY, KG, KZ, MD, RU, TJ, TM), European patent (AT,
`BE, CH, CY, DE, DK, ES, Fl, FR, GB, GR, IE, IT, LU,
`MC, NL, PT, SE), OAPI patent (BF, BJ, CF, CG, CI, CM,
`GA, GN, GW, ML, MR, NE, SN, TD, TG).
`
`Published
`With international search report.
`
`(54) Title: SENSORS ARRANGEMENT
`
`(57) Abstract
`
`An autonomous vehicle (100), such as
`a robotic cleaning device, comprises wheels
`(104) for supporting the vehicle and for
`allowing the vehicle to traverse a surface.
`Downward looking wheel sensors (274, 276)
`are provided for sensing the presence of a
`surface in front of the wheels and a further
`sensor (272) is provided at or near a leading
`edge of the vehicle for sensing the presence
`of a surface beneath the leading edge of
`the vehicle. The vehicle is arranged so
`that movement of the vehicle is possible if
`the leading edge sensor (272) detects the
`absence of a surface beneath the leading
`edge of the vehicle providing the wheel
`sensors (274, 276) indicate the presence
`of a surface adjacent the wheel. When
`the leading edge sensor (272) detects the
`absence of a surface beneath the leading
`edge of the vehicle, the vehicle performs an
`edge following routine.
`
`~320
`r---------------····--·------------·---------'----·----------,
`LEFT
`WHEEL
`D/LOOKER
`
`I
`I
`I
`I
`I
`
`DECISION
`CIRCUIT
`
`RIGHT
`WHEEL
`D/LOOKER
`
`276
`t ..... ---------
`
`--- ...... -...... .,
`
`MOTOR
`DRIVER
`HARDWARE
`
`I
`I
`I
`I
`
`:
`
`I
`I
`I
`I
`I
`I
`I
`
`:
`
`I
`I
`I
`I
`I
`I
`I
`
`0
`
`.--.........
`
`I
`I
`
`306
`
`CONTROL
`SOFTWARE
`
`305
`
`1
`
`Shenzhen Zhiyi 1010
`
`
`
`FOR THE PURPOSES OF INFORMATION ONLY
`
`Codes used to identify States party to the PCT on the front pages of pamphlets publishing international applications under the PCT.
`
`AL
`AM
`AT
`AU
`AZ
`BA
`BB
`BE
`BF
`BG
`BJ
`BR
`BY
`CA
`CF
`CG
`CH
`CI
`CM
`CN
`cu
`CZ
`DE
`DK
`EE
`
`Albania
`Annenia
`Austria
`Australia
`Azerbaijan
`Bosnia and Herzegovina
`Barbados
`Belgium
`Burkina Faso
`Bulgaria
`Benin
`Brazil
`Belarus
`Canada
`Central African Republic
`Congo
`Swit1.erland
`Ci'.\te d'Ivoire
`Cameroon
`China
`Cuba
`Czech Republic
`Germany
`Denmark
`Estonia
`
`ES
`FI
`FR
`GA
`GB
`GE
`GH
`GN
`GR
`HU
`IE
`IL
`IS
`IT
`JP
`KE
`KG
`KP
`
`KR
`KZ
`LC
`LI
`LK
`LR
`
`Spain
`Finland
`France
`Gabon
`United Kingdom
`Georgia
`Ghana
`Guinea
`Greece
`Hungary
`Ireland
`Israel
`Iceland
`Italy
`Japan
`Kenya
`Kyrgyzstan
`Democratic People's
`Republic of Korea
`Republic of Korea
`Kazakstan
`Saint Lucia
`Liechtenstein
`Sri Lanka
`Liberia
`
`LS
`LT
`LU
`LV
`MC
`MD
`MG
`MK
`
`ML
`MN
`MR
`MW
`MX
`NE
`NL
`NO
`NZ
`PL
`PT
`RO
`RU
`SD
`SE
`SG
`
`Lesotho
`Lithuania
`Luxembourg
`Latvia
`Monaco
`Republic of Moldova
`Madagascar
`The fonner Yugoslav
`Republic of Macedonia
`Mali
`Mongolia
`Mauritania
`Malawi
`Mexico
`Niger
`Netherlands
`Norway
`New Zealand
`Poland
`Portugal
`Romania
`Russian Federation
`Sudan
`Sweden
`Singapore
`
`SI
`SK
`SN
`sz
`TD
`TG
`TJ
`TM
`TR
`TT
`UA
`UG
`us
`uz
`VN
`YU
`zw
`
`Slovenia
`Slovakia
`Senegal
`Swaziland
`Chad
`Togo
`Tajikistan
`Turkmenistan
`Turkey
`Trinidad and Tobago
`Ukraine
`Uganda
`United States of America
`Uzbekistan
`Viet Nam
`Yugoslavia
`Zimbabwe
`
`2
`
`
`
`WO 00/38026
`
`PCT/GB99/04090
`
`1
`
`Sensors Arrangement
`
`The invention relates to an arrangement of sensors for an autonomous vehicle,
`
`particularly but not exclusively for an autonomous vacuum cleaner.
`
`5
`
`An autonomous vehicle generally has a plurality of sensors for detecting obstacles in the
`
`path of the vehicle to prevent collision or accidents. While some autonomous vehicles
`
`can cope with undulating surfaces, they usually need to avoid any areas where there is a
`
`significant change in height, such as stairs where there is a danger that the machine can
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`10
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`become stuck or fall, causing damage to the vehicle and to others. It is know to provide
`
`an autonomous vehicle with sensors that monitor the presence of a surface; these are
`
`often called "downlooking" or "drop-off' sensors.
`
`A robotic cleaning device described in Patent Application WO 93/03399 has drop-off
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`15
`
`sensors at a forward edge of the cleaning device and is arranged to stop the drive motors
`
`when one of the drop-off sensors senses the absence of a surface beneath the cleaning
`
`device.
`
`Safety regulations require that downlooking sensors should cause the vehicle to stop
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`20 whenever the sensors detect the absence of a surface. This places severe constraints on
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`flexibility of controlling the vehicle near to any places where there is a significant
`
`change in height. The present invention seeks to provide more flexibility in operating
`
`an autonomous vehicle under these conditions.
`
`25 According to a first aspect of the invention, there is provided an autonomous vehicle
`
`comprising wheels for supporting the vehicle and for allowing the vehicle to traverse a
`
`surface, wherein downward looking wheel sensors are provided for sensing the presence
`
`of a surface in front of the wheels and a further sensor is provided at or near a leading
`
`edge of the vehicle for sensing the presence of a surface beneath the leading edge of the
`
`30
`
`vehicle.
`
`3
`
`
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`WO 00/38026
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`PCT/GB99/04090 _
`
`2
`
`Preferably the vehicle is arranged so that movement of the vehicle is permitted when the
`
`leading edge sensor detects the absence of a surf ace beneath the leading edge of the
`
`vehicle providing the wheel sensors indicate the presence of a surface adjacent the
`
`wheel. This allows more flexibility in controlling movement of the cleaning device.
`
`s
`
`Preferably, the vehicle is arranged to operate so that when the leading edge sensor
`
`detects the absence of a surf ace beneath the leading edge of the vehicle, the vehicle
`
`performs an edge following routine. The edge following routine can be a zig-zag
`
`movement along the edge, or it can use a further downlooking sensor which senses the
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`10
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`presence of a surface adjacent a side edge of the vehicle.
`
`Further aspects of the invention provide a method of operating an autonomous vehicle,
`
`software for performing a method of controlling operation of an autonomous vehicle
`
`and a control apparatus for controlling operation of an autonomous vehicle.
`
`lS
`
`An embodiment of the present invention will now be described, by way of example
`
`only, with reference to the accompanying drawings, wherein:
`
`Figure 1 is a perspective view of an autonomous vehicle, specifically a vacuum cleaner,
`
`20
`
`according to an embodiment of the invention;
`Figure 2 is a front view of the autonomous vehicle of Figure 1;
`
`Figure 3 is a rear view of the autonomous vehicle of Figure 1;
`
`Figures 4a and 4b are side views, taken from the right and left sides respectively, of the
`
`autonomous vehicle of Figure 1;
`
`25
`
`Figures Sa and Sb are underneath and plan views respectively of the autonomous
`
`vehicle of Figure 1;
`
`Figure 6 is a schematic view illustrating the positioning of infra-red sensors on the
`
`autonomous vehicle of Figure 1;
`
`Figure 7 is a schematic view illustrating the grouping of infra-red sensors on the
`
`30
`
`autonomous vehicle of Figure 1;
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`4
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`
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`WO 00/38026
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`PCT/GB99/04090
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`3
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`Figure 8 is a schematic view illustrating the positioning of ultra-sonic sensors on the
`
`autonomous vehicle of Figure 1; and
`
`Figure 9 is a schematic view illustrating the positioning of further infra-red sensors on
`
`the autonomous vehicle of Figure 1;
`
`5
`
`Figure 10 shows the form of a downlooking sensor;
`
`Figure 11 schematically shows how the downlooking sensors are used by the control
`
`system for the vehicle;
`
`Figure 12 shows a control system for the cleaner;
`
`Figure 13 shows one example of a sideways downlooking sensor;
`
`10
`
`Figures 14 and 15 show two ways in which the cleaner can operate when the cleaner
`
`reaches an edge of a surface that it is cleaning; and
`
`Figure 16 is a flow diagram of a method for operating the cleaner.
`
`15
`
`The embodiment illustrated takes the form of an autonomous vacuum cleaner. The
`
`vacuum cleaner 100 shown in the said drawings has a supporting chassis 102 which is
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`generally circular in shape and is supported on two driven wheels 104 and a castor
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`wheel 106. The chassis 102 is preferably manufactured from high-strength moulded
`
`plastics material, such as ABS, but can equally be made from metal such as aluminium
`
`20
`
`or steel. The chassis 102 provides support for the components of the cleaner 100 which
`
`will be described below. The driven wheels 104 are arranged at either end of a diameter
`
`of the chassis 102, the diameter lying perpendicular to the longitudinal axis of the
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`cleaner 100. Each driven wheel 104 is moulded from a high-strength plastics material
`
`and carries a comparatively soft, ridged band around its circumference to enhance the
`
`25
`
`grip of the wheel 104 when the cleaner 100 is traversing a smooth floor. The soft,
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`ridged band also enhances the ability of the wheels 104 to mount and climb over small
`
`obstacles. The driven wheels 104 are mounted independently of one another via support
`
`bearings (not shown) and each driven wheel 104 is connected directly to a motor 105
`
`which is capable of driving the respective wheel 104 in either a forward direction or a
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`30
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`reverse direction. By driving both wheels 104 forward at the same speed, the cleaner
`
`100 can be driven in a forward direction. By driving both wheels 104 in a reverse
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`5
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`
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`WO 00/38026
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`PCT/GB99/04090
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`4
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`direction at the same speed, the cleaner 100 can be driven in a backward direction. By
`
`driving the wheels 104 in opposite directions, the cleaner 100 can be made to rotate
`
`about its own central axis so as to effect a turning manoeuvre. The aforementioned
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`method of driving a vehicle is well known and will not therefore be described any
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`5
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`further here.
`
`The castor wheel 106 is significantly smaller in diameter than the driven wheels 104 as
`
`can be seen from, for example, Figures 4a and 4b. The castor wheel 106 is not driven
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`and merely serves to support the chassis 102 at the rear of the cleaner 100. The location
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`10
`
`of the castor wheel 106 at the trailing edge of the chassis 102, and the fact that the
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`castor wheel 106 is swivellingly mounted on the chassis by means of a swivel joint 110,
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`allows the castor wheel 106 to trail behind the cleaner 100 in a manner which does not
`
`hinder the manoeuvrability of the cleaner 100 whilst it is being driven by way of the
`
`driven wheels 104. The castor wheel 106 can be made from a moulded plastics material
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`15
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`or can be formed from another synthetic material such as Nylon.
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`Mounted on the underside of the chassis 102 is a cleaner head 122 which includes a
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`suction opening 124 facing the surface on which the cleaner 100 is supported. The
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`suction opening 124 is essentially rectangular and extends across the majority of the
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`20 width of the cleaner head 122. A brush bar 125 is rotatably mounted in the suction
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`opening 124 and a motor (not shown) is mounted on the upper surface of the cleaner
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`head 122 for driving the brush bar 125 by way of a drive belt (not shown) extending
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`between a shaft of the motor and the brush bar 125. The cleaner head 122 is mounted
`
`on the chassis 102 in such a way that the cleaner head 122 is able to float on the surface
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`25
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`to be cleaned. This is achieved in this embodiment in that the cleaner head 122 is
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`pivotally connected to an arm (not shown) which in tum is pivotally connected to the
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`underside of the chassis 102. The double articulation of the connection between the
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`cleaner head 122 and the chassis 102 allows the cleaner head to move freely in a vertical
`
`direction with respect to the chassis 102. This enables the cleaner head to climb over
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`30
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`small obstacles such as books, magazines, rug edges, etc. Obstacles of up to
`
`approximately 25mm
`
`in height can be traversed in this way. A flexible or telescopic
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`6
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`
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`WO 00/38026
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`PCT/GB99/04090 _
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`5
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`conduit is located between a rear portion of the cleaner head 122 and an inlet port
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`located in the chassis 102.
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`As can be seen from Figures 5a and 5b, the cleaner head 122 is asymmetrically
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`5 mounted on the chassis 102 so that one side of the cleaner head 122 protrudes beyond
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`the general circumference of the chassis 102. This allows the cleaner 100 to clean up to
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`the edge of a room on the side of the cleaner 100 on which the cleaner head 122
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`protrudes.
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`10
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`The chassis 102 carries a plurality of sensors which are designed and arranged to detect
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`obstacles in the path of the cleaner 100 and its proximity to, for example, a wall or other
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`boundary such as a piece of furniture. The sensors comprise several ultra-sonic sensors
`
`and several infra-red sensors. The array of sensors will be described in more detail
`
`below. Control software, comprising navigation controls and steering devices for
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`15
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`navigating and manoeuvring the cleaner 100 around a defined area in order to clean the
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`carpet or other surface within the area, is housed within a housing 142 located beneath a
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`control panel 144 or elsewhere within the cleaner 100. The specific design of the
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`control software does not form part of the present invention. In the manner of known
`
`autonomous vehicles, the control software is able to receive the outputs of the sensors
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`20
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`and to drive the motors 105 so that obstacles are avoided whilst following a path
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`specified by algorithms appropriate to the nature of the vehicle. Any appropriate
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`software can be used in this way to navigate the cleaner 100 around a room to be
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`cleaned.
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`25
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`The vacuum cleaner 100 also includes a motor and fan unit 150 supported on the chassis
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`102 for drawing dirty air into the vacuum cleaner 100 via the suction opening 124 in the
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`cleaner head 122. The chassis 102 also carries a cyclonic separator 152 for separating
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`dirt and dust from the air drawn into the cleaner 100. The inlet port which
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`communicates with the rear portion of the cleaner head 122 via the conduit mentioned
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`30
`
`above forms the inlet to the cyclonic separator 152. The cyclonic separator, which
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`7
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`
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`WO 00/38026
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`PCT/GB99/04090 _
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`6
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`preferably comprises two cyclones in series, need not be described any further here,
`
`being known technology and described adequately elsewhere.
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`The cyclonic separator 152 is releasable from the chassis 102 in order to allow emptying
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`5
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`of the cyclonic separator 152. A hooked catch (not shown) is provided by means of
`
`which the cyclonic separator 152 is held in position when the cleaner 100 is in use.
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`When the hooked catch is released (by manual pressing of a button 134 located in the
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`control panel 144), the cyclonic separator 152 can be lifted away from the chassis 102
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`by means of gripper portions 170. The cyclonic separator 152 can then be emptied.
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`10
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`Two battery packs 160 are located on the chassis 102 on either side of the cyclonic
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`separator 152. The battery packs 160 are identical and are spaced from the central axis
`
`of the vacuum cleaner 100 by a significant distance, say between 50 and 150 mm.
`
`15
`
`The vacuum cleaner 100 described above operates in the following manner. In order for
`
`the cleaner 100 to traverse the area to be cleaned, the wheels 104 are driven by the
`
`motors 105 which, in turn, are powered by the batteries 160. The direction of
`
`movement of the cleaner 100
`
`is determined by
`
`the control software which
`
`communicates with the sensors which are designed to detect any obstacles in the path of
`
`20
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`the cleaner 100 so as to navigate the cleaner 100 around the area to be cleaned. The
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`normal forward direction of the cleaner 100 is such that the cleaner head 122 trails
`
`behind the driven wheels 104. The battery packs 160 also power the motor and fan unit
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`150 which draws air into the cleaner 100 via the cleaner head 122 and passes it to the
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`cyclonic separator 152 where the dirt and dust is separated from the airflow. The
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`25
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`battery packs 160 are also used to power the motor which drives the brush bar 125
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`which, in turn assists with pick-up, particularly on carpets. The air which exits the
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`cyclonic separator 152 is passed across the motor and fan unit 150 by appropriate
`
`ducting, as is common in many appliances, including vacuum cleaners.
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`30
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`The sensor array forming part of the vacuum cleaner 100 will now be described in more
`
`detail. The array comprises a plurality of ultra-sonic sensors and a plurality of infra-red
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`8
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`
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`WO 00/38026
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`PCT /GB99/04090
`
`7
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`sensors. The majority of the sensors are located in a forward surface 180 of the vacuum
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`cleaner 100. The forward surface 180 is substantially semi-circular in plan view, as can
`
`be seen from Figures Sa and 5b. However, further sensors are located at the uppermost
`
`extremity of the cleaner 100, at the rear of the cleaner 100, immediately over the brush
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`5
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`bar 122, and on the underside of the cleaner 100. Details are given below.
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`Three ultra-sonic sensors 202, 204 and 206, each consisting of an ultra-sonic emitter
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`and an ultra-sonic receiver, are positioned in the forward surface 180. A first of the said
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`ultra-sonic sensors 202, comprising an emitter 202a and a receiver 202b, is directed in a
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`10
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`forward direction so that the emitted signals are transmitted in the normal forward
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`direction of travel of the cleaner 100. A second ultra-sonic sensor 204, comprising an
`
`emitter 204a and a receiver 204b, is directed such that the emitted signals are
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`transmitted outwardly to the left of the cleaner 100 in a direction which is perpendicular
`
`to the direction of transmission by the ultra-sonic sensor 202. A third ultra-sonic sensor
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`15
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`206, comprising an emitter 206a and a receiver 206b, is directed such that the emitted
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`signals are transmitted outwardly to the right of the cleaner 100 in a direction which is
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`perpendicular to the direction of transmission by the ultra-sonic sensor 202 and opposite
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`to the direction of transmission by the ultra-sonic sensor 204. A fourth ultra-sonic
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`sensor 208, comprising an emitter 208a and a receiver 208b, is located in the rear of the
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`20
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`cleaner 100 (see Figure 3) and is directed rearwardly so that the emitted signals are
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`transmitted parallel to the normal forward direction of travel of the cleaner 100 but in
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`the opposite direction. These four sensors 202, 204, 206, 208 detect the presence of
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`walls and obstacles to the front, left, right and rear of the cleaner 100.
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`25 A fifth ultra-sonic sensor 210 is located in the forward surface 180. The fifth ultra-sonic
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`sensor 210 comprises an emitter 210a and a receiver 210b. The fifth ultra-sonic sensor
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`210 is positioned so that the emitter 210a transmits at an angle which is substantially
`
`midway between the directions in which the forward- and left-looking sensors 202, 204
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`transmit.
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`In the embodiment, the sensor 210 transmits in a direction of 45° to the
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`30
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`normal forward direction of travel of the vacuum cleaner 100. As can be seen from
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`9
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`
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`WO 00/38026
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`PCT /GB99/04090
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`8
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`Figure 1, the sensor 210 transmits to the side of the cleaner 100 on which the cleaner
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`head 122 protrudes.
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`Figure 8 shows schematically the arrangement of ultra-sonic sensors 202, 204, 206, 208
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`5
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`and 210 on the vacuum cleaner 100 if the normal direction of forward travel is along the
`
`arrow F.
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`In the arrangement shown, the angle a is 45°, although variations to this
`
`arrangement are possible.
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`The inclusion of the sensor 210 provides the vehicle 100 with greater angular control as
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`10
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`it moves along a wall or other obstacle with the cleaner head 122 close to the wall. The
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`sensor 210 is able to detect the presence of a wall or similar large obstacle and, if the
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`wall or other obstacle alongside which the vehicle is moving disappears (for example,
`
`when a comer is encountered), then the vehicle 100 is made aware of the change earlier
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`than it would have been if the sensor 210 had not been present. This allows the vehicle
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`15
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`to take account of comers and other changes in its environment with greater accuracy
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`and manoeuvrablity.
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`A plurality of infra-red sensors are also included in the forward surface 180. The infra(cid:173)
`
`red sensors comprise emitters 220 and receivers 230. Most of the emitters 220 are
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`20
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`arranged in four groups of three which are spaced substantially evenly around the
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`forward surface 180. A first emitter group 220a comprises a central emitter 222a and
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`two side emitters 224a. A second emitter group 220b comprises a central emitter 222b
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`and two side emitters 224b. A third emitter group 220c comprises a central emitter
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`222c and two side emitters 224c and a fourth emitter group 220d comprises a central
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`25
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`emitter 222d and two side emitters 224d. One of the emitter groups 220b is illustrated
`in Figure 7. Each side emitter 224b is arranged at an angle b of approximately 60° to
`the central emitter 222b. Each emitter 222b, 224b has a beam angle c of approximately
`
`50°. This arrangement creates a field of relatively even emitted signals covering an
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`angle of substantially 170° to 180°. It will be appreciated that a similar field can be
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`30
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`created by providing a larger number of emitters, each having a smaller beam angle than
`
`the arrangement illustrated in Figure 7.
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`10
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`WO 00/38026
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`PCT/GB99/04090
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`9
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`Figure 6 illustrates the arrangement of the emitter groups 220a, 220b, 220c, 220d on the
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`cleaner 100. As will be seen from the figure, the first emitter group 220a is located at
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`the end of a radial line extending at an angle d of 30° to the transverse axis 190 of the
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`cleaner 100 on the left side thereof. The fourth emitter group 220d is located at the end
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`5
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`of a radial line also extending at an angled of 30° to the transverse axis 190 but on the
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`right side of the cleaner 100. The second and third emitter groups 220b, 220c are
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`located at the ends of radial lines extending at an angle e of 60° to the transverse axis
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`190 on the left and right sides of the cleaner 100 respectively. The third emitter group
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`220c is identical to the second emitter group 220b as illustrated in Figure 7. However,
`
`IO
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`the first and fourth emitter groups 220a, 220d each have one side emitter 224a', 224d'
`
`which is specifically directioned so that the signal emitted is parallel to the transverse
`axis 190. This is achieved, in this specific case, by varying the angle b between the
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`relevant central emitter 222a, 222d and the respective side emitter 224a', 224d' from
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`60° to 30°. It will be appreciated that, if either of the angles b and d differ from the
`values given above, then the extent of the variation in angle b between the relevant
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`15
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`central emitter 222a, 222d and the respective side emitter 224a, 224d will need to be
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`adjusted so that the side emitter 224a', 224d' remains directed outwardly in a direction
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`parallel to the transverse axis 190. Two additional emitters 226 are positioned close to
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`the central axis of the cleaner 100 and are directioned so that they emit signals in a
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`20
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`substantially forward direction with respect to the normal direction of travel.
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`The first and fourth emitter groups 220a, 220d are located in a horizontal plane which is
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`vertically spaced from the horizontal plane in which the second and third emitter groups
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`220b, 220c are located. The first and fourth emitter groups 220a, 220d are located at a
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`25
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`higher level than the second and third emitter groups 220b, 220c. The additional
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`emitters 226 are also spaced vertically from the two aforementioned horizontal planes.
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`The arrangement is symmetrical about the longitudinal axis of the cleaner 100. The
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`whole of the array of emitters is designed so that at least two of the emitters will send
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`signals directly to any point in the path of the cleaner (in the forward direction). (This
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`30 will not apply, of course, to points which are extremely close to the cleaner itself.)
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`11
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`WO 00/38026
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`PCT/GB99/04090
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`10
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`The receivers 230 are spaced substantially evenly around the forward surface 180. A
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`first receiver 230a is located adjacent each of the emitters 224a, 224d which are
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`directioned parallel to the transverse axis 190 so as to receive signals therefrom. These
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`receivers 230a are specifically paired with the emitters 224a, 224d. The remaining
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`5
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`receivers 230b are spaced substantially evenly around the forward surface 180 and are
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`not paired with any of the emitters at all. The receivers 230 are all located in a single
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`horizontal plane with the exception of two central receivers 230b which are located
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`adjacent the forward-looking emitters 226. The lack of pairing of the receivers with the
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`emitters gives the cleaner 100 an enhanced ability to detect its position within an
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`10
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`environment and with respect to objects and obstacles.
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`Two passive infra-red detectors 240 are located in the forward surface 180 for the
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`purpose of detecting heat sources such as humans, animals and fires. The passive infra(cid:173)
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`red detector 240 is directioned so that it looks in a forward direction to detect heat
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`15
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`sources in its path.
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`Two forward-looking ultra-sonic sensors 250, each comprising an emitter 250a and a
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`receiver 250b, are positioned at an uppermost extremity of the cleaner 100 so that they
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`are able to sense obstacles immediately in front of the cleaner and at or near an
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`20
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`uppermost extremity thereof. In this case, the sensors 250 are positioned in the casing
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`of the fan and motor unit 150 so that they both look along the uppermost edge of the
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`cyclonic separator 152. The direction of each sensor 250 is parallel to the direction of
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`the other sensor 250. The sensors 250 are able to detect any obstacles which are at a
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`sufficiently high level not to be detected by the sensors arranged in the forward surface
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`25
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`180 but which would constitute an obstruction to the forward movement of the cleaner
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`100. Rearward-looking sensors could also be provided at a high level if required, but
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`none is shown in the embodiment illustrated in the drawings. It will be appreciated that
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`a similar effect can be achieved using sensors (preferably ultra-sonic sensors) positioned
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`lower on the cleaner than the uppermost extremity but directioned so as to look towards
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`30
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`the appropriate area adjacent the uppermost extremity in front of the cleaner 100.
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`12
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`WO 00/38026
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`PCT/GB99/04090 _
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`11
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`Further infra-red sensors 260, 262 are positioned on the chassis 102 immediately above
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`the protruding end of the cleaner head 122. Each sensor 260, 262 comprises an emitter
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`260a, 262a and a receiver 260b, 262b. The first of these sensors 260 is directioned so
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`that the emitter 260a emits a signal in a direction parallel to the longitudinal axis of the
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`5
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`cleaner head 122 or of the brush bar 125. The direction of the signal from the sensor
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`260 is therefore perpendicular to the forward direction of travel and parallel to the
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`direction of the signal emitted by emitter 224a'. The sensor 260 is thus able to detect
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`the distance of a wall or other obstacle along which the cleaner 100 is intended to travel.
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`In combination with the emitter 224a' and the receiver 230a, the sensor 260 is also able
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`10
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`to maintain the direction of travel of the cleaner 100 parallel with the wall or other
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`obstacle along which the cleaner 100 is intended to travel. This is achieved by way of
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`the parallel signals being maintained essentially identical. Any variation between the
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`two signals can be easily recognised and the path of the cleaner 100 can then be
`
`adjusted to compensate for the discrepancy. The arrangement is illustrated in Figure 9.
`
`15 As will be seen from the figure, the distance between the directions of the two signals is
`
`approximately one half of the length of the cleaner 100, although this can be varied to a
`
`considerable extent. Preferably, the distance will not be less than a quarter of the length
`
`of the vehicle nor more than three quarters thereof.
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`20
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`The second of the further infra-red sensors 262 is directioned so that the emitter 262a
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`sends a signal rearwardly in a direction parallel to the direction of travel of the cleaner
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`100. The sensor 262 is able to detect the presence of an obstacle on which the cleaner
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`head 122 may become lodged if the cleaner 100 were traveling in a rearward direction
`
`or turning or rotating about a vertical axis.
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`25
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`Infra-red sensors 272, 274, 276 are provided on the underside of the cleaner 100. Each
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`sensor 272, 274, 276 is directioned so that it looks downwardly towards the surface
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`across which the cleaner 100 travels and which the cleaner 100 is intended to clean.
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`Two downward-looking sensors 274, 276 are provided in the chassis 102 immediately
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`30
`
`in front of each of the driven wheels 104. A further downward-looking sensor 272 is
`
`provided at the front edge of the chassis 102 and on or close to the longitudinal axis of
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`13
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`WO 00/38026
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`12
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`the cleaner 100. Each sensor 272, 274, 276 comprises an emitter and a receiver. In the
`
`embodiment illustrated, the outermost component of each sensor 274, 276 is a receiver
`
`and the innermost component is an emitter. Each of the sensors 272, 274, 276 is
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`capable of detecting the presence or absence of the surface across which the cleaner 100
`
`5
`
`travels. A signal is sent to the control software to bring the cleaner 100 to a halt, or to
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`tum, immediately one of the sensors 274, 276 detects that the surface is absent. This is
`
`likely to be due to the presence of a stairway or other edge of the surface. The cleaner
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`100 is thus prevented from falling from a height in the event that a stairway or other
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`edge is encountered. For safety reasons, each of the sensors located in front of each
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`10 wheel is connected to the control software via different circuits so that, should one
`
`circuit fail, the other sensor will still be functional in order to avoid an accident
`
`occurring. Further downlooking sensors 278, 280 are provided o the underside of the
`
`cleaner 100 adjacent the periphery of the cleaner. Side downlooking sensors 278, 280
`
`are arranged to detect the presence of a surface adjacent a side edge of the vehicle
`
`15
`
`outside of the path of the wheel and forward of the wheel, in the normal direction of
`
`movement of the vehicle. The normal, forward, direction of movement of the vehicle is
`
`shown as arrow 290. These downlooking sensors 278, 280 look diagonally downwards,
`
`so that the sensors can be mounted on the underside of the cleaner where they are
`
`protected from damage.
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`20
`
`Figure 10 shows the form of a downlooking sensor, mounted in the underside 415 of the
`
`vehicle for detecting the presence of surface 410 in proximity to the vehicle. A transmit
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`part of the sensor comprises a source 400, typically on LED, a lens 402 for forming an
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`output of source 400 into a collimated beam directed downwards towards surface 410.
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`25 A receive part comprises a lens 406 for gathering light reflected by surface 410 and a
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`sensor 408 which generates an output 412 for feeding to control circuitry. Sensor 408 is
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`a position sensitive device (PSD) which provides an output that varies according to the
`
`position of