Abstract:
Disclosed herein are navigational systems for automated robotic floor cleaners. RFID passive tags are positioned at specified areas of a floor to be treated so as to increase or decrease dwell time of the cleaning device adjacent the tags. An RFID interrogator on the robot learns from each tag its nature, and based thereon instructs the device to change the dwell time over specified areas. This permits areas of a carpet or other surface requiring extra or less treatment to be cleaned in an optimal manner.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     Not applicable  
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH/DEVELOPMENT  
       [0002]     Not applicable  
       BACKGROUND OF THE INVENTION  
       [0003]     It is desirable to minimize the amount of human labor expended in maintaining and cleaning buildings. The art has therefore developed autonomous robotic devices that can clean or otherwise maintain or treat hard floors, carpeting and similar surfaces without the necessity for a human to be present during the operation of the device.  
         [0004]     Such robotic devices typically have a programmable controller for directing the device in a preferred movement pattern. The controller is linked to motors that drive the wheels of the device. Many of these devices also include sensors to detect positions of the device relative to a pre-set path or relative to an obstacle such as a wall or a staircase. Other of these devices include programming to provide for a pre-set navigational path, and sensors to detect the presence of unexpected obstacles in the pre-set path such that the pre-set path may be altered to avoid the obstacles.  
         [0005]     For example, U.S. Pat. No. 5,682,313 discloses a floor cleaning robot where ultrasonic transponders are placed in a room to help the cleaning robot move about the room. Another example is U.S. Pat. No. 5,165,064 which discloses a mobile robot where infrared beacons are placed in a room to help the robot move about an area.  
         [0006]     U.S. Pat. No. 6,049,745 discloses automatic guided vehicles (factory material movers) wherein radio frequency identification (“RFID”) tags are provided along the path over which the vehicle travels. Each RFID tag is capable of conveying at least one unique radio frequency signal to a remote reader in response to electromagnetic excitation fields emitted by a remote interrogator. The vehicle has a computer and the remote RFID interrogator and reader. The computer is responsive to characteristic area conditions identified by the RFID reader for navigating the vehicle through the area. The RFID tags can thereby provide directions to a destination for the vehicle.  
         [0007]     Similarly, U.S. Pat. No. 6,459,966 describes a passenger train that is navigated along a route using RFIDs. A route is provided for a vehicle, which corresponds to RFIDs having a memory storing in advance the RFIDs own location information on the route. An RFID interrogator is mounted on the train which transmits radio waves to the RFIDs. In response, the RFIDs provide information to the train&#39;s reader regarding location. A controller on the vehicle then controls a moving direction of the vehicle based on the position information to guide the vehicle along the route.  
         [0008]     For various other navigational and obstacle avoidance systems applied to robotic devices see generally U.S. Pat. Nos. 6,370,452, 6,594,844, 6,671,592 and 6,690,134.  
         [0009]     While various electromagnetic systems have therefore been used for navigational control and obstacle avoidance in autonomous robots, the above listed systems have not been designed to automatically alter the dwell time of the robot in response to temporary conditions (e.g. a heavily soiled area requiring extra cleaning time; a particular area that is so clean as not to require substantial additional cleaning during this cleaning opportunity). As a result, cleaning performance of such robots has not yet been optimized.  
         [0010]     Therefore, a need exists for improved robotic floor treaters where the dwell time of the device can be easily and reliably altered to account for temporary conditions.  
       BRIEF SUMMARY OF THE INVENTION  
       [0011]     The invention provides one or more RFID tags that can be positioned along or adjacent to a floor surface to interact with a controller on a robotic floor treater (e.g. cleaner) so as to change a default dwell time of the treater over an area adjacent the tag. In one form, the tag can be positioned on the floor (e.g. on a carpet) and can transmit a signal causing the treater to treat for a greater amount of time adjacent the tag. In another form, the tag can be positioned on the floor and can transmit a signal causing the treater to spend less time (or even no time) adjacent the area of the floor adjacent that tag.  
         [0012]     The robot will have an RFID interrogator that transmits signals to such an RFID tag, and an RFID reader that receives signals induced from the RFID tag by the interrogator. The robot will also preferably have a controller that interprets the type of signal that the reader has received, and based thereon provides navigational instructions to the device so as to cause the device to alter the amount of dwell time adjacent the tag.  
         [0013]     Thus, a consumer can mark a portion of a carpet or the like where there is a spot or extra soil by placing the RFID tag near it. This will cause the device to clean for a longer period near the tag. RFID tags could be permanently placed near entryways or high traffic areas that are typically more heavily soiled.  
         [0014]     Alternatively, a consumer can place a different type of RFID tag adjacent a portion of the floor which is either too clean to need further treatment, or coated with fresh polish or other chemicals. This will cause the controller to be informed that the dwell time near that should be reduced or eliminated, depending on the tag. Tags could also be used to avoid problem areas—areas where either the appliance could become stuck or damaged. (Typically small area rugs pose difficulties for robotic cleaners as loose edges of the rugs can easily be caught in the rotating brush). Tags could also be used in place of other cliff detection methods to avoid stairs or potentially damaging level changes.  
         [0015]     The tag can be designed to control a specified radius around the tag (e.g. one meter), or can be designed to control a specified area adjacent and at one side of the tag. In any event, the tags may be employed for temporary or permanent use. When used on a temporary basis, the tag would typically be removed from the floor after a single cleaning event. When used on a permanent basis the tag may be left in place, mounted on a surface, or built into the area where it will be employed. For example, the tags would be mounted to surfaces for multiple uses. For instance, the tag could be attached or mounted permanently or removably to the underside of an area rug or piece of furniture in order to hide the tag. Tags could also be color matched with the environment to allow them to be placed in the open—and still blend with surroundings. Tags could also provide an improved method of room confinement vs. other known methods. The tags are small and less conspicuous than magnetic strips or bulky IR beam emitting devices presently used by some devices.  
         [0016]     In preferred forms the invention provides a mobile autonomous robotic floor cleaning device that transmits a low-power radio frequency (“RF”) signal aimed primarily in front of the device and that has the ability to receive digital RF signals back from passive RFID tags. Intelligent, passive (no-power) RFID tags intercept the mobile robot&#39;s RF signal and use the RF signal to power the RFID tag and then transmit an intelligent-digital RF signal back to the mobile robot, informing the robot of the presence of the RFID tag and what kind of RFID tag. The robot has a controller with a processor having a software algorithm to interpret the digital data and act on it accordingly, e.g., stay longer, spend less time.  
         [0017]     The mobile robot may or may not change its course based on receiving the signal from the RFID tag. In this regard, it may simply slow or quicken the speed of travel. Alternatively, the robot may enter a spiral path around the tag where additional dwell time is desired.  
         [0018]     The RFID tag is preferably of the passive type, meaning that it does not transmit a signal on its own absent external stimulation. The RFID tag may thus only transmit a signal to the mobile robot when the robot is sufficiently near the tag and the robot&#39;s RF energy has intercepted the tag.  
         [0019]     In one form, the method of powering the RFID tags is by induction coupling, although other techniques such as propagating electromagnetic waves can be used. The RF signal from the RFID tag is a carrier signal that is transmitting an intelligent digital signal (32 bits, typical). The use of intelligent digital signal transmission allows for specific awareness by the mobile robot of detection and discrimination between tags and the objects in a room that the tags may be placed near.  
         [0020]     For example, an RFID tag may be placed on a small oriental rug that is not to be treated with the same chemicals as the floor surrounding it. In such a case, an RFID tag labeled “stay away” would be positioned on the center of the rug during the cleaning operation. Alternatively, where dirt had been tracked on a defined area of a carpet a “clean more” tag could be positioned next to the dirt. Or again, the tags could be mounted in high traffic areas that are more likely to be more highly soiled.  
         [0021]     Thus, the invention provides a system for navigating an automatic cleaning device within a location such as a room. The system includes one or more radio frequency identification tags positioned within or adjacent a selected surface area of the location. The system further includes an automatic cleaning device for treating the surface area.  
         [0022]     Typically, the automatic cleaning device includes motors for driving a left wheel and a right wheel, and the motors are each controlled by the controller which includes a microprocessor under the control of a software program stored in the controller memory. The controller is in communication with a radio frequency identification unit which receives signals from the radio frequency identification tag indicating presence of the selected surface area. The radio frequency identification unit is typically located on the automatic cleaning device, albeit it could be for applying other chemicals (e.g. polishing), or providing other functions (e.g. buffing).  
         [0023]     The stored program of the controller that drives the automatic cleaning device may use different routines. For instance, a radio frequency identification tag may be positioned in the center of the selected surface area, and the stored program drives the automatic cleaning device within a predetermined distance of the radio frequency identification tag for the extended time period. Alternatively, a plurality of radio frequency identification tags may positioned on a perimeter of the selected surface area, and the stored program drives the automatic cleaning device within the perimeter of the selected surface area for the extended time period.  
         [0024]     Hence, the present invention provides inexpensive and reliable means of temporarily marking areas of a floor being treated for greater or lesser dwell time, thereby causing automatic instructions to be implemented by an automated robot to reduce or increase treatments adjacent those tags.  
         [0025]     The foregoing and other advantages of the invention will become apparent from the following description. In the following description reference is made to the accompanying drawing which forms a part thereof, and in which there is shown by way of illustration preferred embodiments of the invention. These embodiments do not represent the full scope of the invention. Reference should therefore be made to the claims herein for interpreting the scope of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]      FIG. 1  is an exploded rear perspective view of an autonomous robotic surface treating device of the present invention;  
         [0027]      FIG. 2  is an exploded frontal perspective view of the device of  FIG. 1 ;  
         [0028]      FIG. 3  is a view similar to  FIG. 1 , but with upper housings removed;  
         [0029]      FIG. 4  is a view similar to  FIG. 2 , but with upper housings removed;  
         [0030]      FIG. 5  is a schematic view illustrating how a take-up reel of the assembly is ratcheted for one-way motion;  
         [0031]      FIG. 6  is an enlarged perspective view of an end of a supply reel of the present assembly;  
         [0032]      FIG. 7  is a view similar to  FIG. 1 , but showing the device in fully assembled form;  
         [0033]      FIG. 8  is a sectional view taken along line  8 - 8  of  FIG. 7 ;  
         [0034]      FIG. 9  is an enlarged view of the reel-to-reel portion of the present device, highlighting a portion of the  FIG. 8  drawing;  
         [0035]      FIG. 10  is a front, left, upper perspective view of an alternative cartridge useful with the  FIG. 1  device, when cleaning carpeting;  
         [0036]      FIG. 11  is a view similar to  FIG. 10 , but with an upper cover removed;  
         [0037]      FIG. 12  is a top, left, frontal perspective view of the autonomous robotic surface treating device of  FIG. 1 , but altered to include the RFID based navigational system of the present invention;  
         [0038]      FIG. 13  is a perspective view of a robotic device of the present invention in operation in a room marked with the RFID tags of the present invention; and  
         [0039]      FIG. 14  is a schematic view of an RFID tag&#39;s electronics. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0040]     We first describe example autonomous cleaning devices with reference to  FIGS. 1-11 . This provides examples of environments where the invention of the present invention can be applied. Thereafter, we describe with reference to  FIGS. 12-14  specific features of the present invention.  
         [0041]     It should be understood that the present invention is also suitable for use with many other types of autonomous treating devices. Thus, the invention is not intended to be restricted to just cleaning devices, much less devices having the specific attributes shown in  FIGS. 1-11 .  
         [0042]     Referring particularly to  FIGS. 1 and 3 , there is a cleaning cartridge  10  suitable to be inserted into a cleaning device  12 . The cleaning cartridge  10  has a roll of sheet form cleaning cloth  44  which is provided in a reel-to-reel configuration. A portion of the roll is maintained in contact with the surface below the cleaning device  12  at any given time during operation. A motor  52  is provided in the cleaning device  12  to consistently index the cleaning sheet material, so as to maintain a relatively fresh sheet against the floor.  
         [0043]     Referring now also to FIGS.  FIGS. 2 and 4 , the cleaning device  12  is in the form of an autonomous robot which includes a housing  13  having an aperture  14  sized and dimensioned to receive the cleaning cartridge  10 . In the housing  13  and located above the aperture  14  are two windows  22  and  24  which allow the user to view the cleaning cartridge  10 , and the roll of cleaning cloth  44  maintained therein.  
         [0044]     An aperture  25  is also provided which, in conjunction with a latching device  27  on the cartridge  10 , provides a latch for selectively connecting the cartridge  10  to the cleaning device  12 . The cleaning device  12  also includes a bumper  15  at a front end and side brushes  16 . As shown in  FIG. 8 , the cleaning device  12  also includes a sweeper brush  60  for cleaning large particulate matter. The cleaning cloth  44  follows the brush  60  and typically cleans smaller particulate matter such as hair and dust which have not been picked up through the use of the brush  60 .  
         [0045]     The cartridge  10  includes windows  26  and  28  which, when positioned in the cleaning device  12 , are aligned with the windows  22  and  24  in the housing  13  of the cleaning device  12 , thereby allowing a user visual access to the cleaning cloth  44  within the cartridge  10 . A dust bin  30  is provided in the cleaning cartridge  10  at the end of the cartridge which is received inside of the housing  13  of the cleaning device  12 .  
         [0046]     The dust bin  30  is designed to be positioned adjacent the brush  60  ( FIG. 8 ) in the cleaning device  12 . It is selectively covered by a hinged lid  38 , which is forced open as the cleaning cartridge  10  is moved into the cleaning device  12  but which swings shut and is therefore normally closed when the cartridge is removed from the cleaning device  12 , thereby retaining dust collected by the cleaning device  12  within the dust bin  30  for cleaning, replacement, or disposal of the cartridge  10 .  
         [0047]     A flexible blade  32  is provided in front of the dust bin  30 , directed from an upper edge of the dust bin  30  to the surface below the cartridge  10 . The flexible blade  32  directs dirt collected by the brush  60  of the cleaning device  12  into the dust bin  30 .  
         [0048]     The reel-to-reel device provided in the cartridge  10  includes both a take-up reel  34 , to which used cleaning cloth  44  is directed, and a supply reel  36 , to which an unused roll of cleaning sheet material is connected and from which the cleaning process is supplied. The take-up reel  34  ( FIG. 5 ) is ratcheted in order to prevent used cleaning cloth  44  from being directed back over the surface to be cleaned, while the supply reel  36  ( FIG. 6 ) provides a resistive force limiting rolling of the sheet unless driven by the stepper motor  52 . Teeth  35  in the take-up reel  34  are engaged with spring-loaded teeth  33  to ratchet the reel and limit motion.  
         [0049]     The cleaning cloth  44  can comprise, for example, an electrostatic or electret material. Examples of such materials are those described in WO 02/00819. The cleaning cloth  44  can also provide a liquid treating or dispensation function. For example, the cleaning cloth can be treated with cleaning fluid or polishes to treat the floor with surfactants, insecticides, insect repellants, and/or fragrances.  
         [0050]     The cartridge  10  can further comprise a fluid reservoir  42  for providing a fluid to the cleaning cloth  44  during operation. The fluid supply provided in the reservoir  42  is connected to a pump  50  provided in the cleaning device  12  through fluid inlets  40  provided on the cartridge  10  and fluid outlets  48  provided on the cleaning device  12 . In operation, therefore, the control of fluid flow to the cleaning cloth  44  is controlled by the cleaning device  12 , and is provided to the sheet material to maintain a selected level of moisture over the life of the cartridge.  
         [0051]     A bank of batteries  54  provides power to the cleaning device, which is selectively activated by a switch  18  ( FIG. 1 ) provided on the cleaning device  12 . The batteries are preferably rechargeable, and are accessed through a port  55  provided in the side of the housing of the cleaning device  12  ( FIG. 2 )  
         [0052]     The cloth supply reel  36  is driven by the stepper motor  52  provided in the cleaning device and the amount of the roll of the cleaning cloth  44  which is unwound during operation is monitored by an optical sensor  46 , which is also provided in the cleaning device  12 . The stepper motor  52 , optical sensor  46 , and pump  50  are each driven by a programmable controller (not shown, but positioned above the battery pack) based on timing which drives the stepper motor to replace the sheet material as necessary to maintain proper cleaning processes during a cleaning operation while monitoring actual movement of the sheet.  
         [0053]     Similarly, the controller drives the pump  50  to supply fluid to the roll of cleaning cloth  44  as necessary during cleaning. The timing for replenishment of the fluid source is based on the type of material and fluid being employed, and in the expected life of the roll of cleaning cloth  44 . The controller preferably maintains the cleaning cloth  44  in a constant tension, and, while in use, indexes at a predetermined rate, as for example, 0.75 inches per 5 minutes or thereabout, over the life of the cartridge. The stepper motor  52  is coupled to the take-up reel  34  through a series of gears, while the supply reel is coupled to the optical sensor which detects the amount of rotation of the supply wheel.  
         [0054]     Referring now to  FIGS. 8 and 9 , the cleaning device  12  includes a beater or sweeping brush  60 . A wheel  62  at the front of the cleaning device  12  is adjustable by activation of a switch  20  between at least two positions, one selected for use with a carpet, and another for use with a hard floor surface. As the cartridge  10  is inserted into the cleaning device  12  the flexible blade  32  is positioned adjacent the main brush  60  and receives the relatively large particulate matter collected by the brush as the cleaning device  12  is run across a floor surface. The particulates are directed up the flexible blade  32  by the main brush  60  and into the dust bin  30 .  
         [0055]     In operation the hinged lid  38  is retained in an open position such that the dust and particulate matter can be readily directed into the dust bin  30 . Following behind the main brush  60  is the cartridge  10  including the cleaning cloth  44 . The cleaning cloth  44  is retained against the surface to be cleaned by a platen  66  which includes a leaf-spring  64  that insures contact between the surface to be cleaned and the cleaning cloth  44 . Also as described above, the reservoir  42  is provided adjacent the cleaning cloth  44  such that fluids can be applied to replenish the cloth when a wet or moist mop cloth is employed in the cleaning device  12 .  
         [0056]     Although a cleaning cloth  44  has been shown and described particularly designed for use on a hard, smooth floor, a cartridge  10  for use with a carpet is shown in  FIGS. 10 and 11 . Here, the cartridge comprises a larger dust bin  30 , and is weighted appropriately to maintain the cleaning device  12  against the surface to be cleaned, and in an upright position during the cleaning operation.  
         [0057]     The cartridge  10  preferably is a replaceable element that can be thrown away as a unit when the sheet material is used up, the fluid in the fluid reservoir  42  is spent, or the dust bin is full. Furthermore, even before the cleaning material is spent, the cartridge  10  can be removed and the dust bin  30  emptied by the user with minimal dust dispersion.  
         [0058]     In an alternative embodiment (not shown), the fluid reservoir  42  can deliver fluid directly to the floor during operation. The fluid supply provided in the reservoir  42  is connected to the pump  50  provided in the cleaning device  12  through fluid inlets  40  provided on the cartridge  10  and fluid outlets  48  provided on the cleaning device  12 . The controller drives the pump  50  to supply fluid to the floor as necessary during cleaning.  
         [0059]     Turning now to key features of the present invention, the cleaning device  12  includes motors  70  and  71  for driving the left wheel  74  and the right wheel  75  of the cleaning device  12 , respectively. The motors  70 ,  71  are each controlled by the programmable controller which includes a microprocessor under the control of a software program stored in a memory. Among other things, the controller provides voltage signals to the motors  70  and  71  that cause the left wheel  74  and the right wheel  75  to start, stop, rotate in a direction causing forward motion of the cleaning device  12 , rotate in a direction causing reverse motion of the cleaning device  12 , and rotate at increased or decreased speeds.  
         [0060]     An encoder is associated with each wheel  74 , 75  and is connected to the controller. Encoders are commercially available and in one version, the encoder outputs a signal having a pulse every time each wheel  74 , 75  rotates a predetermined angle. For example, an optical encoder outputs pulses each time an optical beam is broken by an element that rotates with the wheel. The controller respectively calculates the wheel speed of each wheel  74 , 75  based upon an interval between pulses outputted from each encoder. Changes in the interval between pulses can also be used by the controller to calculate wheel acceleration.  
         [0061]     Among other things, the controller can use calculated wheel speeds to control motion of the left wheel  74  and the right wheel  75 . In one example algorithm, the controller provides a positive voltage in the range of 0 to +10 volts to each motor  70  and  71  to drive the left wheel  74  and the right wheel  75  in forward motion. The controller uses calculated wheel speeds to determine the amount of voltage to be applied the motors  70  and  71  to control motion of the left wheel  74  and the right wheel  75 . Voltage controls the motor speed as voltage will typically be proportional to motor speed. The controller provides a negative voltage in the range of 0 to −10 volts to each motor  70  and  71  to drive the left wheel  74  and the right wheel  75  in reverse motion.  
         [0062]     Turning next to focus on  FIGS. 12-14 , the controller is also in electrical communication with radio frequency identification device units  80  that are mounted on the bumper  15  of the cleaning device  12 . The RFID units  80  include a radio frequency tag reader which receives unique radio frequency signals from RFID tags (as discussed below) in response to electromagnetic excitation fields emitted from an antenna interrogator in each RFID unit  80 . Alternative locations on the cleaning device  12  for the RFID units  80  are also suitable (e.g. top of the housing).  
         [0063]     The navigational system includes a number of RFID tags that are placed at selected locations in a room to be cleaned. For example, as indicated in  FIG. 13 , a set of RFID tags  90   w  can be placed on the baseboard of a wall  92  of the room to be cleaned; another set of RFID tags  90   s  can be placed at the entry to the room  96  adjacent steps  93 . Yet another set of RFID tags  90   c  can be placed on the legs of a chair  94  in the room to be cleaned. Still another set of RFID tags  90   r  can be placed on the perimeter of a delicate rug  95 .  
         [0064]     The tags  90   w  could signal the device to spend longer along the wall to try to pick up crumbs that get caught along the edge of the room. This would be achieved by signaling a slow linear motion.  
         [0065]     The tags  90   s  could signal the device to spend longer in a small region near the tags, but not to pass the tags. The tags  90   c  could signal the device to spend longer adjacent the tags, but with a avoidance area within several inches of the tag.  
         [0066]     The tags  90   r  could signal the device to move quickly over an area adjacent the tags. This would help clean the designated throw rug, without endangering its delicate nature.  
         [0067]      FIG. 14  depicts an electrical schematic of an RFID tag such as  90   w ,  90   s ,  90   r  or  90   c . There is optionally (but not necessarily) some form of battery power  116  which is connected by line  120  and line  122  to drive an integrated circuit transceiver chip  124 . The IC transceiver chip  124  is connected to an antenna  128  which transmits RF signals from the IC transceiver chip  124  and receives incoming RF excitation signals.  
         [0068]     The RFID tag&#39;s  114  electronics components may be mounted on a suitable substrate such as a plastic or ceramic substrate. The term “radio frequency identification device” as used herein means any device capable of communicating by radio frequency. For example, the term “radio frequency identification device” encompasses devices that transmit or receive any data by radio frequency, not just identification data. One type of RFID is described in U.S. Pat. No. 5,497,140.  
         [0069]     Still referring to  FIG. 14 , the IC transceiver chip  124  of the RFID tag  114  includes an RF receiver  168  and an RF transmitter  170 , both connected through line  172  to antenna  128 . The receiver  168  is connected through line  180  to a control logic  182 , and a line  184  from the control logic  182  is connected to the memory  186 . A line  188  from the memory  186  connects back to the control logic  182 , and a line  190  from the control logic  182  connects to the transmitter  170  for providing stored data to the transmitter  170  via the control logic  182 .  
         [0070]     In operation information is transmitted to the receiver  168  via an RF communication link including data such as the room object type (e.g., wall, staircase, chair, rug, etc.). This information received at the receiver  168  is then transmitted over line  180  and through the control logic  182  which sorts this information out in a known manner and in turn transmits the data to be stored in memory  186 . The data encoding operation typically will be done by the manufacturer so that a user of the cleaning device  12  is provided with RFID tags  90   w ,  90   s ,  90   r ,  90   c  appropriately labeled. For example, the RFID tags  90   w ,  90   s ,  90   r ,  90   c  may have external labels such as wall, staircase, chair, rug, etc.  
         [0071]     The incoming RF signals from the antenna of the RFID unit  80  on the cleaning device  12  will send interrogation signals to the RFID tag  114  where they will be received at the antenna  128 . The interrogation signals will pass through the receiver  168  and control logic  182  to the memory  186 . The memory  186  will produce information relating to the room object type (e.g., wall, staircase, chair, rug, etc.) and generate this data back through the control logic  182  into the transmitter  170  so that the transmitter  170  can now transmit this data to the radio frequency tag reader on the RFID unit  80  of the cleaning device  12 .  
         [0072]     When the cleaning device  12  is placed on the floor  97  of the room, the activation switch  18  is pressed to activate the navigational system for directing the cleaning device  12  about the floor  97  of the room to be cleaned for a predetermined time period (e.g., sixty minutes). The program in the controller may begin directing the cleaning device  12  about the floor  97  using any number of known behaviors.  
         [0073]     U.S. Pat. No. 6,809,490, which is incorporated herein by reference along with all other documents cited herein, describes various initial modes in which the cleaning device  12  may operate. For example, the cleaning device  12  may begin with spiral behavior in which the program provides for outward spiral movement generated by increasing the turning radius of the cleaning device  12  as a function of time. Alternatively, the cleaning device  12  may begin with straight line behavior. Also, the cleaning device  12  may begin with wall-following behavior wherein the cleaning device  12  uses a wall-following sensor to position itself a set distance from the wall  92  and proceeds to travel along the perimeter of the wall  92 . Also, the cleaning device  12  may begin with bounce behavior in which the cleaning device  12  travels until a bump sensor in bumper  15  is activated by contact with an obstacle.  
         [0074]     Regardless of the initial behavior programmed in the controller directing the cleaning device  12 , the cleaning device  12  will eventually approach one of the RFID tags  90   w ,  90   s ,  90   r ,  90   c . The RF signals from the antenna of the RFID unit  80  on the cleaning device  12  will send interrogation signals to the RFID tags  90   w ,  90   s ,  90   r ,  90   c . The interrogation signals will pass through the RFID tag receiver and control logic to the memory. The RFID tag memory will produce information relating to the room object type (e.g., wall, staircase, chair, rug, etc.) and generate this data back through the control logic into the transmitter so that the transmitter transmits this data to the radio frequency tag reader on the RFID unit  80  of the cleaning device  12 . The RFID unit  80  of the cleaning device  12  then communicates the encountered room object type to the controller.  
         [0075]     The software in the controller then determines what action the cleaning device  12  needs to take based on the room object type data received from the RFID unit  80 . For instance, if the controller receives data from the RFID unit  80  indicating that the cleaning device  12  has come upon a delicate rug  95  (i.e., RFID tag  90   r  has been encountered), the controller executes a selected software routine speeding up the device so as to dwell less on the rug. The speed is then reduced after the rug is passed over.  
         [0076]     Of course, these example software routines can be programmed and stored into the controller of the cleaning device  12 . In this manner, “attraction” routines that provide for extended cleaning or other treatment, and “avoidance” routines that reduce dwell times can all be executed by the controller.  
         [0077]     Although specific embodiments of the present invention have been described in detail, it should be understood that this description is merely for purposes of illustration. Many modifications and variations to the specific embodiments will be apparent to those skilled in the art, which will be within the spirit and scope of the invention. Therefore, the invention should not be limited to the described embodiments. Rather, the claims should be looked to in order to judge the full scope of the invention.  
       INDUSTRIAL APPLICABILITY  
       [0078]     Disclosed are RFID-based systems for automatically altering the dwell time of robotic cleaners with respect to defined surface areas.