Patent Publication Number: US-11641996-B2

Title: Robotic cleaner

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation of U.S. patent application Ser. No. 16/438,552, filed Jun. 12, 2019, which is a continuation-in-part of U.S. patent application Ser. No. 16/217,748, filed Dec. 12, 2018, which claims the benefit of U.S. Provisional Patent Application No. 62/609,449 filed Dec. 22, 2017, all of which are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     Autonomous or robotic floor cleaners can move without the assistance of a user or operator to clean a floor surface. For example, the floor cleaner can be configured to sweep dirt (including dust, hair, and other debris) into a collection bin carried on the floor cleaner or to sweep dirt using a cloth which collects the dirt. The floor cleaner can move randomly about a surface while cleaning the floor surface or use a mapping/navigation system for guided navigation about the surface. Some floor cleaners are further configured to apply and extract liquid for deep cleaning carpets, rugs, and other floor surfaces. 
     BRIEF SUMMARY 
     In one aspect, the disclosure relates to a floor cleaning robot. The floor cleaning robot includes an autonomously moveable housing, and a unitary assembly removably mounted to the autonomously moveable housing, the unitary assembly including a brush chamber and a debris receptacle. The floor cleaning robot also includes a brushroll located in the brush chamber, a supply tank, and at least one fluid distributor in fluid communication with the supply tank. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG.  1    is a schematic view of an exemplary autonomous floor cleaner illustrating functional systems in accordance with various aspects described herein. 
         FIG.  2    is a schematic view of the autonomous floor cleaner of  FIG.  1    illustrating additional functional systems in accordance with various aspects described herein. 
         FIG.  3    is an isometric view of the autonomous floor cleaner of  FIG.  1    in the form of a floor cleaning robot in accordance with various aspects described herein. 
         FIG.  4    is an isometric view of the underside of the floor cleaning robot of  FIG.  3   . 
         FIG.  5    is a side elevation cross-sectional view of the floor cleaning robot of  FIG.  3   . 
         FIG.  6    is a schematic illustration of a dusting assembly of the cleaning robot of  FIG.  3   . 
         FIG.  7    is an isometric view of the underside of the floor cleaning robot of  FIG.  3    illustrating a bumper assembly. 
         FIG.  8    is an isometric view of the floor cleaning robot of  FIG.  3    illustrating a fluid spray nozzle. 
         FIG.  9    is a cross-sectional view of a tank assembly in the floor cleaning robot of  FIG.  3   . 
         FIG.  10    is a schematic illustration of a wheel assembly that can be utilized in the floor cleaning robot of  FIG.  1   . 
         FIG.  11    is a schematic illustration of another wheel assembly that can be utilized in the floor cleaning robot of  FIG.  1   . 
         FIG.  12    is an isometric view of another floor cleaning robot in accordance with various aspects described herein. 
         FIG.  13    is an isometric view of the floor cleaning robot of  FIG.  12    illustrating a tank assembly. 
         FIG.  14    is an isometric view of the tank assembly of  FIG.  13    illustrating a fluid supply tank and a debris receptacle. 
         FIG.  15    is an isometric view of the tank assembly of  FIG.  14    illustrating a coupling between the fluid supply tank and the debris receptacle. 
         FIG.  16    is a front isometric view of another floor cleaning robot in accordance with various aspects described herein. 
         FIG.  17    is a rear isometric view of the floor cleaning robot of  FIG.  16   . 
         FIG.  18    is a rear isometric view of the floor cleaning robot of  FIG.  16   , showing a tank assembly in a partially removed state. 
         FIG.  19    is a close-up view of section XIX of  FIG.  18   . 
         FIG.  20    is a rear isometric view of the floor cleaning robot of  FIG.  16   , with the tank assembly removed for clarity. 
         FIG.  21    is a cross-sectional view taken through line XXI-XXI of  FIG.  16   . 
         FIG.  22    is a close-up isometric cross-sectional view taken through line XXI-XXI of  FIG.  16   , showing a brush chamber of the floor cleaning robot  FIG.  21   . 
         FIG.  23    is an isometric view of an underside of the tank assembly of the floor cleaning robot of  FIG.  16   . 
         FIG.  24    is a side elevation view of the tank assembly of  FIG.  23   , showing a lid is a partially removed state. 
         FIG.  25    is an isometric view of the tank assembly of  FIG.  24   . 
         FIG.  26    is an isometric view of a lower portion of the tank assembly of  FIG.  24   , with the lid removed. 
         FIG.  27    is a cross-sectional view taken through line XVII-XVII of  FIG.  17   . 
         FIG.  28    is an isometric view of another tank assembly that can be utilized in the floor cleaning robot of  FIG.  16   . 
         FIG.  29    is an isometric view of another tank assembly that can be utilized in the floor cleaning robot of  FIG.  16   . 
         FIG.  30    is an isometric view of another tank assembly that can be utilized in the floor cleaning robot of  FIG.  16   . 
     
    
    
     DETAILED DESCRIPTION 
     The disclosure generally relates to autonomous floor cleaners for cleaning floor surfaces, including hardwood, tile and stone. More specifically, the disclosure relates to devices, systems and methods for sweeping and mopping with an autonomous floor cleaner. 
       FIGS.  1  and  2    illustrate a schematic view of an autonomous floor cleaner, such as a floor cleaning robot  10 , also referred to herein as a robot  10 . It is noted that the robot  10  shown is but one example of a floor cleaning robot configured to sweep as well as dust, mop or otherwise conduct a wet cleaning cycle of operation, and that other autonomous cleaners requiring fluid supply or fluid recovery are contemplated, including, but not limited to autonomous floor cleaners capable of delivering liquid, steam, mist, or vapor to the surface to be cleaned. 
     The robot  10  can include components of various functional systems in an autonomously moveable unit. The robot  10  can include a main housing  12  ( FIG.  3   ) adapted to selectively mount components of the systems to form a unitary movable device. A controller  20  is operably coupled with the various functional systems of the robot  10  for controlling the operation of the robot  10 . The controller  20  can be a microcontroller unit (MCU) that contains at least one central processing unit (CPU). 
     A navigation/mapping system  30  can be provided in the robot  10  for guiding the movement of the robot  10  over the surface to be cleaned, generating and storing maps of the surface to be cleaned, and recording status or other environmental variable information. The controller  20  can receive input from the navigation/mapping system  30  or from a remote device such as a smartphone (not shown) for directing the robot  10  over the surface to be cleaned. The navigation/mapping system  30  can include a memory  31  that can store any data useful for navigation, mapping or conducting a cycle of operation, including, but not limited to, maps for navigation, inputs from various sensors that are used to guide the movement of the robot  10 , etc. For example, wheel encoders  32  can be placed on the drive shafts of wheels coupled to the robot  10  and configured to measure a distance traveled by the robot  10 . The distance measurement can be provided as input to the controller  20 . 
     In an autonomous mode of operation, the robot  10  can be configured to travel in any pattern useful for cleaning or sanitizing including boustrophedon or alternating rows (that is, the robot  10  travels from right-to-left and left-to-right on alternate rows), spiral trajectories, etc., while cleaning the floor surface, using input from various sensors to change direction or adjust its course as needed to avoid obstacles. In a manual mode of operation, movement of the robot  10  can be controlled using a mobile device such as a smartphone or tablet. 
     The robot  10  can also include at least the components of a sweeper  40  for removing debris particles from the surface to be cleaned, a fluid delivery system  50  for storing cleaning fluid and delivering the cleaning fluid to the surface to be cleaned, a mopping or dusting assembly  60  for removing moistened dust and other debris from the surface to be cleaned, and a drive system  70  for autonomously moving the robot  10  over the surface to be cleaned. 
     The sweeper  40  can also include at least one agitator for agitating the surface to be cleaned. The agitator can be in the form of a brushroll  41  mounted for rotation about a substantially horizontal axis, relative to the surface over which the robot  10  moves. A drive assembly including a separate, dedicated brush motor  42  can be provided within the robot  10  to drive the brushroll  41 . Other agitators or brushrolls can also be provided, including one or more stationary or non-moving brushes, or one or more brushes that rotate about a substantially vertical axis. In addition, a debris receptacle  44  ( FIG.  4   ) such as a dustbin can be provided to collect dirt or debris from the brushroll  41 . 
     The fluid delivery system  50  can include a supply tank  51  for storing a supply of cleaning fluid and at least one fluid distributor  52  in fluid communication with the supply tank  51  for depositing a cleaning fluid onto the surface. The cleaning fluid can be a liquid such as water or a cleaning solution specifically formulated for hard or soft surface cleaning. The fluid distributor  52  can be one or more spray nozzles provided on the housing  12  with an orifice of sufficient size such that debris does not readily clog the nozzle. Alternatively, the fluid distributor  52  can be a manifold having multiple distributor outlets. 
     A pump  53  can be provided in the fluid pathway between the supply tank  51  and the at least one fluid distributor  52  to control the flow of fluid to the at least one fluid distributor  52 . The pump  53  can be driven by a pump motor  54  to move liquid at any flowrate useful for a cleaning cycle of operation. 
     Various combinations of optional components can also be incorporated into the fluid delivery system  50 , such as a heater  56  or one or more fluid control and mixing valves. The heater  56  can be configured, for example, to warm up the cleaning fluid before it is applied to the surface. In one embodiment, the heater  56  can be an in-line fluid heater between the supply tank  51  and the distributor  52 . In another example, the heater  56  can be a steam generating assembly. The steam assembly is in fluid communication with the supply tank  51  such that some or all the liquid applied to the floor surface is heated to vapor. 
     The dusting assembly  60  can be utilized to disperse the distributed fluid on the floor surface and remove moistened dust and other debris. The dusting assembly  60  can include at least one pad  61  that can optionally be rotatable. For example, the at least one pad  61  can be driven to rotate about a vertical axis that intersects with the center of the respective pad  61 . A drive assembly including at least one pad motor  62  can be provided as part of the dusting assembly  60 . Each pad  61  can be optionally be detachable for purposes of cleaning and maintenance. 
     The drive system  70  can include drive wheels  71  for driving the robot  10  across a surface to be cleaned. The drive wheels can be operated by a common wheel motor  72  or individual wheel motors coupled with the drive wheels by a transmission, which may include a gear train assembly or another suitable transmission. The drive system  70  can receive inputs from the controller  20  for driving the robot  10  across a floor, based on inputs from the navigation/mapping system  30  for the autonomous mode of operation or based on inputs from a smartphone for the manual mode of operation. The drive wheels  71  can be driven in a forward or reverse direction to move the unit forwardly or rearwardly. Furthermore, the drive wheels  71  can be operated simultaneously at the same rotational speed for linear motion or independently at different rotational speeds to turn the robot  10  in a desired direction. 
     The robot  10  can include any number of motors useful for performing locomotion and cleaning. In one example, five dedicated motors can be provided to rotate each of two pads  61 , the brushroll  41 , and each of two drive wheels  71 . In another example, one shared motor can rotate both the pads  61 , a second motor can rotate the brushroll  41 , and a third and fourth motor can rotate each drive wheel  71 . In still another example, one shared motor can rotate the pads  61  and the brushroll  41 , and a second and third motor can rotate each drive wheel  71 . 
     In addition, a brush motor driver  43 , pump motor driver  55 , pad motor driver  63 , and wheel motor driver  73  can be provided for controlling the brush motor  42 , pump motor  54 , pad motors  62 , and wheel motors  72 , respectively. The motor drivers  43 ,  55 ,  63 ,  73  can act as an interface between the controller  20  and their respective motors  42 ,  54 ,  62 ,  72 . The motor drivers  43 ,  55 ,  63 ,  73  can also be an integrated circuit chip (IC). It is also contemplated that a single wheel motor driver  73  can control multiple wheel motors  72  simultaneously. 
     Turning to  FIG.  2   , the motor drivers  43 ,  55 ,  63 ,  73  ( FIG.  1   ) can be electrically coupled to a battery management system  80  that includes a built-in rechargeable battery or removable battery pack  81 . In one example, the battery pack  81  can include lithium ion batteries. Charging contacts for the battery pack  81  can be provided on an exterior surface of the robot  10 . A docking station (not shown) can be provided with corresponding charging contacts that can mate to the charging contacts on the exterior surface of the robot  10 . The battery pack  81  can be selectively removable from the robot  10  such that it can be plugged into mains voltage via a DC transformer for replenishment of electrical power, i.e. charging. When inserted into the robot  10 , the removable battery pack  81  can be at least partially located outside the housing  12  ( FIG.  3   ) or completely enclosed in a compartment within the housing  12 , in non-limiting examples and depending upon the implementation. 
     The controller  20  is further operably coupled with a user interface (UI)  90  on the robot  10  for receiving inputs from a user. The user interface  90  can be used to select an operation cycle for the robot  10  or otherwise control the operation of the robot  10 . The user interface  90  can have a display  91 , such as an LED display, for providing visual notifications to the user. A display driver  92  can be provided for controlling the display  91 , and acts as an interface between the controller  20  and the display  91 . The display driver  92  may be an integrated circuit chip (IC). The robot  10  can further be provided with a speaker (not shown) for providing audible notifications to the user. The robot  10  can further be provided with one or more cameras or stereo cameras (not shown) for acquiring visible notifications from the user. In this way, the user can communicate instructions to the robot  10  by gestures. For example, the user can wave their hand in front of the camera to instruct the robot  10  to stop or move away. The user interface  90  can further have one or more switches  93  that are actuated by the user to provide input to the controller  20  to control the operation of various components of the robot  10 . A switch driver  94  can be provided for controlling the switch  93 , and acts as an interface between the controller  20  and the switch  93 . 
     The controller  20  can further be operably coupled with various sensors for receiving input about the environment and can use the sensor input to control the operation of the robot  10 . The sensors can detect features of the surrounding environment of the robot  10  including, but not limited to, walls, floors, chair legs, table legs, footstools, pets, consumers, and other obstacles. The sensor input can further be stored in the memory or used to develop maps for navigation. Some exemplary sensors are illustrated in  FIG.  2   , and described below. Although it is understood that not all sensors shown may be provided, additional sensors may be provided, and that all of the possible sensors can be provided in any combination. 
     The robot  10  can include a positioning or localization system  100 . The localization system  100  can include one or more sensors, including but not limited to the sensors described above. In one non-limiting example, the localization system  100  can include obstacle sensors  101  determining the position of the robot  10 , such as a stereo camera in a non-limiting example, for distance and position sensing. The obstacle sensors  101  can be mounted to the housing  12  ( FIG.  3   ) of the robot  10 , such as in the front of the housing  12  to determine the distance to obstacles in front of the robot  10 . Input from the obstacle sensors  101  can be used to slow down or adjust the course of the robot  10  when objects are detected. 
     Bump sensors  102  can also be provided in the localization system  100  for determining front or side impacts to the robot  10 . The bump sensors  102  may be integrated with the housing  12 , such as with a bumper  14  ( FIG.  3   ). Output signals from the bump sensors  102  provide inputs to the controller for selecting an obstacle avoidance algorithm. 
     The localization system  100  can further include a side wall sensor  103  (also known as a wall following sensor) and a cliff sensor  104 . The side wall sensor  103  or cliff sensor  104  can be optical, mechanical, or ultrasonic sensors, including reflective or time-of-flight sensors. The side wall sensor  103  can be located near the side of the housing  12  and can include a side-facing optical position sensor that provides distance feedback and controls the robot  10  so that robot  10  can follow near a wall without contacting the wall. The cliff sensors  104  can be bottom-facing optical position sensors that provide distance feedback and control the robot  10  so that the robot  10  can avoid excessive drops such as stairwells or ledges. 
     The localization system  100  can also include an inertial measurement unit (IMU)  105  to measure and report the robot&#39;s acceleration, angular rate, or magnetic field surrounding the robot  10 , using a combination of at least one accelerometer, gyroscope, and, optionally, magnetometer or compass. The inertial measurement unit  105  can be an integrated inertial sensor located on the controller  20  and can be a nine-axis gyroscope or accelerometer to sense linear, rotational or magnetic field acceleration. The IMU  105  can use acceleration input data to calculate and communicate change in velocity and pose to the controller for navigating the robot  10  around the surface to be cleaned. 
     The localization system  100  can further include one or more lift-up sensors  106  which detect when the robot  10  is lifted off the surface to be cleaned e.g. if a user picks up the robot  10 . This information is provided as an input to the controller  20 , which can halt operation of the pump motor  54 , brush motor  42 , pad motor  62 , or wheel motors  73  in response to a detected lift-up event. The lift-up sensors  106  may also detect when the robot  10  is in contact with the surface to be cleaned, such as when the user places the robot  10  back on the ground. Upon such input, the controller  20  may resume operation of the pump motor  54 , brush motor  42 , pad motor  62 , or wheel motors  73 . 
     The robot  10  can optionally include one or more tank sensors  110  for detecting a characteristic or status of the supply tank  51  or the debris receptacle  44 . In one example, one or more pressure sensors for detecting the weight of the supply tank  51  or the debris receptacle  44  can be provided. In another example, one or more magnetic sensors for detecting the presence of the supply tank  51  or debris receptacle  44  can be provided. This information is provided as an input to the controller  20 , which may prevent operation of the robot  10  until the supply tank  51  is filled, the debris receptacle  44  is emptied, or both are properly installed, in non-limiting examples. The controller  20  may also direct the display  91  to provide a notification to the user that either or both of the supply tank  51  and debris receptacle  44  is missing. 
     The robot  10  can further include one or more floor condition sensors  111  for detecting a condition of the surface to be cleaned. For example, the robot  10  can be provided with an IR dirt sensor, a stain sensor, an odor sensor, or a wet mess sensor. The floor condition sensors  111  provide input to the controller that may direct operation of the robot  10  based on the condition of the surface to be cleaned, such as by selecting or modifying a cleaning cycle. Optionally, the floor condition sensors  111  can also provide input for display on a smartphone. 
     An artificial barrier system  120  can also be provided for containing the robot  10  within a user-determined boundary. The artificial barrier system  120  can include an artificial barrier generator  121  that comprises a barrier housing with at least one signal receiver for receiving a signal from the robot  10  and at least one IR transmitter for emitting an encoded IR beam towards a predetermined direction for a predetermined period of time. The artificial barrier generator  121  can be battery-powered by rechargeable or non-rechargeable batteries or directly plugged into mains power. In one non-limiting example, the receiver can comprise a microphone configured to sense a predetermined threshold sound level, which corresponds with the sound level emitted by the robot  10  when it is within a predetermined distance away from the artificial barrier generator. Optionally, the artificial barrier generator  121  can further comprise a plurality of IR emitters near the base of the barrier housing configured to emit a plurality of short field IR beams around the base of the barrier housing. The artificial barrier generator  121  can be configured to selectively emit one or more IR beams for a predetermined period of time, but only after the microphone senses the threshold sound level, which indicates the robot  10  is nearby. Thus, the artificial barrier generator  121  can conserve power by emitting IR beams only when the robot  10  is near the artificial barrier generator  121 . 
     The robot  10  can have a plurality of IR transceivers (also referred to as “IR XCVRs”)  123  around the perimeter of the robot  10  to sense the IR signals emitted from the artificial barrier generator  121  and output corresponding signals to the controller  20 , which can adjust drive wheel control parameters to adjust the position of the robot  10  to avoid boundaries established by the artificial barrier encoded IR beam and the short field IR beams. Based on the received IR signals, the controller  20  prevents the robot  10  from crossing an artificial barrier  122  or colliding with the barrier housing. The IR transceivers  123  can also be used to guide the robot  10  toward the docking station, if provided. 
     In operation, sound (or light) emitted from the robot  10  greater than a predetermined threshold signal level is sensed by the microphone (or photodetector) and triggers the artificial barrier generator  121  to emit one or more encoded IR beams for a predetermined period of time. The IR transceivers  123  on the robot  10  sense the IR beams and output signals to the controller  20 , which then manipulates the drive system  70  to adjust the position of the robot  10  to avoid the barriers  122  established by the artificial barrier system  120  while continuing to perform a cleaning operation on the surface to be cleaned. 
     The robot  10  can operate in one of a set of modes. The modes can include a wet mode, a dry mode and a sanitization mode. During a wet mode of operation, liquid from the supply tank  51  is applied to the floor surface and both the brushroll  41  and the pads  61  are rotated. During a dry mode of operation, the brushroll  41 , the pads  61 , or a combination thereof, are rotated and no liquid is applied to the floor surface. During a sanitizing mode of operation, liquid from the supply tank  51  is applied to the floor surface and both the brushroll  41  and the pads  61  are rotated and the robot  10  can select a travel pattern such that the applied liquid remains on the surface of the floor for a predetermined length of time. The predetermined length of time can be any duration that will result in sanitizing floor surfaces including, but not limited to, two to five minutes. However, sanitizing can be effected with durations of less than two minutes and as low as fifteen seconds. 
     It is also contemplated that the pump  53  ( FIG.  1   ) can be driven according to a pulse-width modulation (PWM) signal  28 . Pulse-width modulation is a method of communication by generating a pulsing signal. Pulse-width modulation can be utilized for controlling the amplitude of digital signals in order to control devices and applications requiring power or electricity, such as the pump motor  54 . The PWM signal  28  can control an amount of power given to the pump  53  by cycling the on-and-off phases of a digital signal at a predetermined frequency and by varying the width of an “on” phase. The width of the “on” phase is also known as duty cycle, which is expressed as the percentage of being “fully on” (100%). The pump  53  can essentially receive a steady power input with an average voltage value which is the result of the duty cycle and can be less than the maximum voltage capable of being delivered from the battery pack  81 . The PWM signal  28  can be transmitted from the controller  20  and configured to provide a set flowrate of deposited cleaning fluid. In one non-limiting example of operation, the PWM signal  28  can cyclically energize the pump  53  for a first predetermined time duration, such as 40 milliseconds, and then de-energize the pump for a second predetermined time duration, such as 2 seconds, at a rate of 50 Hz and a duty cycle of 40%. Higher flow rates can be achieved by, for example, increasing either of both of the duty cycle or frequency. In this manner, the controller  20  can provide for any suitable or customized flow rate, including a low flow rate, from the pump  53  being powered from the battery pack  81 . 
       FIG.  3    illustrates the exemplary robot  10  that can include the systems and functions described in  FIGS.  1 - 2   . As shown, the robot  10  can include a D-shaped housing  12  with a first end  13  and a second end  15 . The first end  13  defines a housing front  11  of the robot  10  which is a straightedge portion of the D-shaped housing  12 , and can be formed by the bumper  14 . The second end  15  can define a housing rear  16  which is a rounded portion of the D-shaped housing  12 . The battery pack  81  and supply tank  51  can also be mounted to the housing  12  as shown. 
     Forward motion of the robot  10  is illustrated with an arrow  17 , and the bumper  14  wraps around the first end  13  of the robot  10  to provide a lateral portion  18  along the D-shaped front region of the robot  10 . In the illustrated example, the bumper  14  includes a lower crenellated structure  19  which is described in more detail below. During a collision with an obstacle, the bumper  14  can shift or translate to register a detection of an object. 
     The robot  10  is shown in a lower perspective in  FIG.  4   , where an underside portion  21  of the housing  12  is visible. The robot  10  can include the sweeper  40  with brushroll  41 , at least one wheel assembly with a drive wheel  71 , and the dusting assembly  60  which is illustrated with two circular pads  61 . The brushroll  41  can be positioned within a brush chamber  22 . The brushroll  41  and brush chamber  22  can be located proximate the first end  13 , e.g. proximate the straightedge portion of the housing  12 . Along the bottom surface of the robot  10  and with respect to forward motion of the robot  10 , the sweeper  40  is mounted ahead of the pads  61  and drive wheels  71  are disposed therebetween. In addition, the debris receptacle  44  can be positioned adjacent the brushroll  41  and brush chamber  22 . In the illustrated example, the debris receptacle  44  is positioned in line with the drive wheels  71 , between the brush chamber  22  and pads  61 . 
     The robot  10  can also include one or more casters  74  set behind the brush chamber  22 . The casters  74  can include a wheel mounted on an axle, or an omnidirectional ball for rolling in multiple directions, in non-limiting examples. The one or more casters  74  can, in one example, be utilized to maintain a minimum spacing between the surface to be cleaned and the underside portion  21  of the robot  10 . 
     In another example (not shown), a squeegee can optionally be provided on the housing  12 , such as behind the pads  61 . In such a case, the squeegee can be configured to contact the surface as the robot  10  moves across the surface to be cleaned. The squeegee can wipe any remaining residual liquid from the surface to be cleaned, thereby leaving a moisture and streak-free finish on the surface to be cleaned. In a dry application, the squeegee can prevent loose debris from being propelled by the brushroll  41  to the rear of the robot  10 . 
       FIG.  5    is a side elevation cross-sectional view of the robot  10 . The supply tank  51  and debris receptacle  44  can be separate components within the robot  10 . Alternately, the supply tank  51  and debris receptacle  44  can be integrated into a single tank assembly. 
     The supply tank  51  can define at least one supply reservoir  51 R to store liquid for application, via the pump  53  ( FIG.  1   ), to a surface of a floor to be cleaned by the dusting assembly  60 . The debris receptacle  44  can define at least one receptacle reservoir  44 R and can include a receptacle inlet  45  directly adjacent, and open to, the brush chamber  22 . The brush chamber  22  can include a partition having a ramped front surface  24  provided at a bottom of the receptacle inlet  45  to guide debris into the debris receptacle  44 . In operation, dirt or debris swept up by rotation of the brushroll  41  can be moved by the brushroll  41  through the brush chamber  22 , including along the ramped front surface  24 , and propelled through the receptacle inlet  45  into the debris receptacle  44 . 
     Optionally, pad holders  64  can be utilized to mount the circular pads  61  to the housing  12 . In such a case, the pad holders  64  can include rotation plates and form the bottom of the base of the dusting assembly  60 . The pad holders  64  can include a bottom cover through which a motor shaft of the pad motor  62  extends. The pad motor  62  rotates the motor shaft via a suitable transmission, such as a worm gear assembly that can rotate the pad holder  64  and, consequently, the pad  61 . The coupling between the motor shaft and the rotatably driven pad holder  64  defines a vertical axis of rotation for the pad  61 . 
     To remove the pads  61  for cleaning, the dusting assembly  60  can include selectively removable elements. In one non-limiting example, the selectively removable elements can be the pads  61 , and in such a case a user or consumer can remove the pads  61  for cleaning or replacement. In another non-limiting example, the removable elements include detachable elements such as the pad holder  64  which couple the pads  61  to the pad motor  62 . In such a case, a consumer can release the removable elements (e.g. the pad holders  64 ) through any suitable decoupling means and can then remove the pads  61  from the removable elements for cleaning or replacement. In one example, the removable elements are released from the robot  10  via an actuator  65  directly coupled to a mechanical catch and latch assembly. It is also contemplated that the pad holders  64  can also be rotatable along with the pads  61  in the dusting assembly  60 . 
     Alternatively, or in addition to the selectively removable elements, a cleaning station (not shown) can be provided to aid in cleaning or replacing the pads  61  of the dusting assembly  60 . The robot  10  can be placed on the cleaning station and can apply or assist in a cleaning operation for the pads  61 . In one example, the cleaning station can include a surface provided with a plurality of bosses or nubs for agitating the bottom of the pads  61 . The robot  10  can activate a self-cleaning mode where the pads  61  are rotated while in contact with the plurality of bosses or nubs to produce an agitation process that mechanically cleans the pads  61 . 
       FIG.  6    illustrates additional details of the dusting assembly  60 . The robot  10  can optionally include a pad-lifting assembly  66  that selectively and automatically lifts the pads  61  off the floor surface whenever the robot  10  comes to a complete stop. In the illustrated example, the dusting assembly  60  including the rotating pads  61  are coupled to a movable frame that includes a spring  67  which is biased to provide vertical separation between the pads  61  and the floor surface. A user can initiate a cleaning cycle of operation, for example, by pressing a button  75  that activates a microswitch  68  and displaces the dusting assembly  60  from a raised position, with the pads  61  out of contact with the floor surface, downwardly to a lowered position in which the pads  61  contact the floor surface. The dusting assembly  60  can be selectively retained in the lowered position by a catch  69  that is selectively movable by another actuator  65  such as a solenoid. The robot  10  can be configured to activate the actuator  65  to move the catch  69  and release the dusting assembly  60  after a cleaning cycle of operation such that the spring  67  urges the dusting assembly  60  to translate back to the raised position. In this manner, the pads  61  can be out of contact with the floor surface while drying, thus preventing streaking and staining of the floor surface directly beneath the pads  61 . 
     In another example (not shown), the pad-lifting assembly  66  can include a caster  74  coupled to an actuator, such as a solenoid, configured to affect a linear motion that extends the caster  74  downward from a first raised position to a second lowered position. The caster  74  can travel downward to contact the surface of the floor and at which point it raises at least a rear portion of the robot  10  until the pads  61  are no longer in contact with the floor surface. In another example, the robot  10  can selectively engage the pad-lifting assembly  66  to raise the pads  61  off the floor surface at the completion of a scheduled cleaning cycle of operation. 
     In still another example (not shown), the robot  10  can vary the speed and direction of the rotation of the pads  61 . The robot  10  can select the speed and rotation according to a cycle of operation to aid or improve cleaning or locomotion of the robot  10 . In one example, the pads  61  can counter-rotate such that the front edge of each pad  61  is spinning away from the fluid distributor  52  ( FIG.  1   ) or spray nozzle  57  ( FIG.  8   ). The rate of spinning can include any rate useful for performing a cleaning cycle of operation including, but not limited to a range of rotations per minute from  80  to  120 . However, slower and faster rotations may be advantageous for specialized cleaning modes. 
       FIG.  7    illustrates the underside of the robot  10  with the bumper  14  shown in additional detail. A lower portion of the bumper  14  can include a crenellated structure  19  of interleaved merlons  25  and crenels  26 . In other words, the lower portion of the bumper  14  has a series of projecting lead-ins (merlons  25 ) that direct debris into the openings (crenels  26 ) disposed along the lower leading edge of the bumper  14  between adjacent merlons  25 . Such a configuration allows the robot  10  to detect surface transitions, such as from a hard surface to an area rug or carpet, through sensors on the forward bumper  14  while also allowing debris to pass through the crenels  26 . The merlons  25  can be formed of a substantially trapezoidal cross-section where the shorter base of the trapezoid forms the leading edge of the bumper  14  with respect to the forward motion of the robot  10 . In this way, debris can be funneled along the legs of the trapezoidal merlons  25  to the sweeper  40  (e.g. the brushroll  41  and brush chamber  22 ) configured behind the bumper  14 . In another example (not shown), the debris receptacle  44  can include a flapper to prevent the collected debris from inadvertently spilling out of the debris receptacle  44  during removal or transport to a waste container. 
       FIG.  8    is an isometric view of the robot  10  illustrating further details of the fluid delivery system  50 . In the example shown, the distributor  52  includes a spray nozzle  57  fluidly coupled to the supply tank  51  ( FIG.  3   ) via the pump  53 . The spray nozzle  57  can be positioned between adjacent pads  61  as shown. In one example, cleaning fluid dispensed from the spray nozzle  57  can be delivered directly to the floor surface, and the rotating pads  61  can absorb and remove the applied cleaning fluid from the floor surface, including during a wet mode of operation of the robot  10  as described above. 
     A cross-sectional view of the debris receptacle  44  and supply tank  51  is shown in  FIG.  9   . The supply tank  51  can further include a valve  58  with an outlet  59  that is fluidly connected to a downstream portion of the fluid delivery system, such as the spray nozzle  57  ( FIG.  8   ). In one example, the valve  58  can comprise a plunger valve removably mounted to an open neck on bottom of the supply tank  51 . A mechanical closure  29 , such as a threaded cap, can secure the valve  58  to the supply tank  51  and be easily removed for refilling the supply tank  51  when necessary. In the example shown, the supply tank  51  includes a single supply reservoir  51 R for water or a combination of water and a cleaning formula. In another example (not shown), the supply tank  51  can includes a first reservoir for storing water and a second reservoir for storing a cleaning formula. It is contemplated that the robot  10  can include multiple supply tanks, a single supply tank with multiple reservoirs or chambers therein, or the like, or combinations thereof for storing cleaning fluid within the robot  10 . 
       FIG.  10    is a schematic illustration of a wheel assembly  76  of the robot  10  having parallel linkages  77  and an extension spring  78 . The wheel assembly  76  in the illustrated example includes one or more drive wheel subassemblies. A drive wheel subassembly includes at least one drive wheel  71  coupled to a wheel housing  79  via at least one linkage  77 . The at least one linkage  77  can include any element useful for raising or lowering the wheel  71  with respect to the wheel housing  79 . The wheel housing  79  is coupled to the chassis or housing  12  of the robot  10 . In addition, the extension spring  78  can include a first end  83  coupled to the housing  12  or a sensor thereon, such as the lift-up sensor  106  ( FIG.  2   ). A second end  84  of the extension spring  78  can couple to any suitable portion of the robot  10 , illustrated with an exemplary first position  85  on a housing of the wheel motor  72 , or an exemplary second position  86  directly on the at least one linkage  77 , in non-limiting examples. 
     During locomotion of the robot  10 , if the drive wheels  71  traverse an obstacle such as a threshold or power cord, the linkages  77  can rotate while the drive wheels  71  can partially rise into the wheel housing  79 , aided by the extension spring  78 , such that the pads  61  remain in contact with the floor surface. During locomotion of the robot  10 , if the drive wheels  71  lose contact with the floor surface, the drive wheels  71  can lower from the wheel housing  79  and indicate that the robot  10  has been lifted from the floor surface. 
       FIG.  11    is a schematic illustration of another wheel assembly  76 B similar to the wheel assembly  76 . One difference is that the wheel assembly  76 B includes a compression spring  78 B biasing the drive wheels  71  downward toward the surface to be cleaned. Another difference is that the wheel assembly  76 B can include non-parallel first and second linkages  77 A,  77 B coupling the drive wheels  71  to the wheel housing  79 . The non-parallel linkages  77 A,  77 B, can, in one example, be utilized in combination with the compression spring  78 B to direct the drive wheels  71  in a customized direction or path of movement in the event of the robot  10  traversing an obstacle such as a flooring threshold or power cord. The compression spring  78 B can be coupled at a first position  85 B to the housing of the wheel motor  72 , or directly to either of the non-parallel linkages  77 A.  77 B as illustrated with a second position  86 B. 
     Referring now to  FIG.  12   , another autonomous floor cleaner, such as another floor cleaning robot  210  is illustrated that can include the various functions and system as described in  FIGS.  1 - 2   . The robot  210  is similar to the robot  10 ; therefore, like parts will be identified with like numerals increased by 200, with it being understood that the description of the like parts of the robot  10  applies to the robot  210 , except where noted. 
     The robot  210  can include the D-shaped main housing  212  adapted to selectively mount components of the systems to form a unitary movable device. One difference is that the robot  210  can include a sweeper  240  without including a dusting assembly as described above. 
     Another difference is that the robot  210  can be driven in an opposite direction as compared to the robot  10 , where an arrow  217  illustrates a direction of motion of the robot  10  during operation. More specifically, a first end  213  forming a straight-edge portion of the D-shaped housing  212  can define the housing rear  216 , and a second end  215  forming a rounded edge of the housing  212  can define the housing front  211 . 
     Another difference is that the robot  210  can further include a unitary or integrated tank assembly  246 . Turning to  FIG.  13   , the integrated tank assembly  246  can include a supply tank  251  and debris receptacle  244 . The tank assembly  246  is shown in a partially-removed state from the housing  212 . It is contemplated that the tank assembly  246  can be selectively removed by a consumer such that both the supply tank  251  and the debris receptacle  244  are removed together in one action. For example, the tank assembly  246  can include a hook-and-catch mechanism wherein a hook  247  on the tank assembly  246  engages with a catch  248  on the housing  212  of the robot  210 . A handle  249  can be provided on the tank assembly  246 , wherein a user can grasp the handle  249  and rotate the tank assembly  246  to disengage the tank assembly  246  from the housing  212 . 
     It is further contemplated that the tank assembly  246  can at least partially define the brush chamber  222 . The brushroll is not shown in this view for clarity; however, any suitable agitator including one or more brushrolls can be provided. The brush chamber  222  can be open to the debris receptacle  244  as described above. In the illustrated example, the brushroll (not shown) can be located at the rear of the housing  212  when the robot  210  moves in the direction indicated by the arrow  217 . Optionally, a bumper  214  can form the second end  215  of the housing  212 . 
       FIG.  14    illustrates the tank assembly  246  in isolation with the supply tank  251  and debris receptacle  244 . The supply tank  251  can be positioned above the debris receptacle  244 . It is further contemplated that the debris receptacle  244  can be selectively removable from the supply tank  251 . Any suitable mechanism can be utilized, such as a second hook-and-catch mechanism (not shown) between the supply tank  251  and debris receptacle  244 . A release button  295  or other actuator can optionally be provided for selective detachment of the debris receptacle  244  from the tank assembly  246 . 
       FIG.  15    illustrates removal of the debris receptacle  244  from the supply tank  251 . The debris receptacle  244  can be rotated downward and away from the supply tank  251  to access the receptacle reservoir  244 R, such as for complete removal and cleanout of the receptacle  244 . It can also be appreciated that removal of the supply tank  251  and debris receptacle  244  in a single integrated tank assembly  246  can improve usability, wherein a consumer can remove the tank assembly  246  in a single action to fill the supply tank  251  with cleaning fluid and remove debris from the receptacle  244 . 
     Referring now to  FIGS.  16 - 17   , another autonomous floor cleaner, such as another floor cleaning robot  410  is illustrated that can include the various functions and system as described in  FIGS.  1 - 2   . The robot  410  is similar to the robot  10 ; therefore, like parts will be identified with like numerals increased by 400, with it being understood that the description of the like parts of the robot  10  applies to the robot  410 , except where noted. 
     The robot  410  can include a D-shaped main housing  412  adapted to selectively mount components of the systems to form a unitary movable device. The D-shaped housing  412  has a first end  413  and a second end  415 . The robot  410  can be driven in an opposite direction as compared to the robot  10 , where an arrow  417  illustrates a direction of motion of the robot  410  during operation. More specifically, a first end  413  forming a straight-edge portion of the D-shaped housing  412  can define the housing rear  416 , and a second end  415  forming a rounded edge of the housing  412  can define the housing front  411 . Optionally, a bumper (not shown) can be provided at the second end  415 . 
     Another difference is that the robot  410  can include a vacuum collection or recovery system for removing the liquid and debris from the floor surface, and storing the recovered liquid and debris in a debris receptacle  444  (or recovery tank). The details of one embodiment of the vacuum collection or recovery system for the robot  410  are described in more detail below. 
     Another difference is that the robot  410  shown does not include a mopping and dusting assembly as described above, although in other embodiments the robot  410  can be provided with one or more vertically-rotating dusting pads as described above. 
     Another difference is that the robot  410  includes a unitary or integrated tank assembly  446 . The integrated tank assembly  446  can include at least a supply tank  451  and the debris receptacle  444 . It is further contemplated that the debris receptacle  444  can be selectively removable from the supply tank  451 . A cover  427  defining a brush chamber  422  can be formed with or otherwise coupled to the tank assembly  446 , and can be removed from the housing  412  along with the tank assembly  446  as one unit. 
     Referring to  FIG.  18   , it is contemplated that the tank assembly  446  can be selectively removed by a consumer such that the supply tank  451 , the debris receptacle  444 , and the brush chamber  422  are removed together in one action. A handle  449  can be provided on the tank assembly  446 , wherein a user can grasp the handle  449  and rotate the tank assembly  446  to disengage the tank assembly  446  from the housing  412 . It is contemplated that the handle  449  can serve two purposes. First, when the tank assembly  446  is attached to the housing  412 , the handle  449  can be used to carry the entire robot  410 . Second, when the tank assembly  446  is not attached to the housing  412 , the handle  449  can be used to carry the tank assembly  446 . 
     The tank assembly  446  can be attached to the housing  412  using any suitable mechanism. In one exemplary embodiment, referring additionally to  FIG.  19   , the robot  410  can include a pivot coupling for movement of the tank assembly  446  about axis A, shown herein as a hook-and-catch mechanism that allows the tank assembly  446  to be fully separated from the housing  412 . The hook-and-catch mechanism can include a hook  447  on the tank assembly  446  that engages with a catch  448  on the housing  412  of the robot  410 . Two hooks  447  can be provided on opposing lateral sides of a rear portion of the tank assembly  446 , or on the cover  427 , with corresponding catches  448  provided on opposing lateral sides of the first end  313  or housing rear  416  of the housing  412 . Alternatively, the hooks  447  can be provided on the housing  412  and the catches  448  can be provided on the tank assembly  446 . 
     In addition, a latch  433  can secure a portion of the tank assembly  446  to the housing  412 . Of course, in other embodiments of the robot  410 , the tank assembly  446  can be secured to the housing  412  using just a hook-and-catch mechanism or just a latch mechanism. The latch  433  includes a latch actuator, such as a latch button  434  that is depressed by the user to release the tank assembly  446 . The latch  433  can be any suitable latch, catch, or other mechanical fastener that can join the tank assembly  446  and housing  412 , while allowing for the regular separation of the tank assembly  446  from the housing  412 , such as a spring-biased latch operable via the latch button  434 . 
     The tank assembly  446  is shown in a partially-removed state from the housing  412  in  FIG.  18   . The tank assembly  446  can be removed from the housing  412  by pressing the latch button  434  and rotating the tank assembly  446  as shown in  FIG.  18   , about an axis A defined by the hook-and-catch mechanism. Once the hooks  447  have cleared the catches  448 , the tank assembly  446  can be lifted upwardly away from the housing  412 . This process can be performed with one hand. Optionally, the handle  449  can be proximate to, i.e. lie close enough to, the latch button  434  so that the consumer can grip the handle  449  with one hand and actuate the latch  433  using the same hand, e.g. press the latch button  434  with a finger or thumb of the same hand. Having the tank assembly  446  removable from the top side of the housing  412  also provides a benefit for charging or docking the robot  410  because the tank assembly  446  can be removed when the robot  410  is seated in the charging cradle or docking station. 
     Having the latch  433  on the housing  412  and the handle  449  on the tank assembly  246  can provide some further benefits to the tank removal process. The consumer must provide opposing forces to lift the tank assembly  446  upwardly while simultaneously pressing downward on the housing  412 . This helps create a clean breakaway between the two assemblies and keeps the housing  412  in position during removal of the tank assembly  446 . This can be particularly helpful if the robot  410  is in a charging cradle or at a docking station when the consumer removes the tank assembly  446 . The tank assembly  446  can be removed without disturbing any electrical contact needed for charging the battery (not shown). 
     The tank assembly  446  combines the supply tank  451 , debris receptacle  444 , and brush chamber  422  in one unitary assembly or module. These parts of the robot  410  are serviced most frequently, and providing them in a single unit allows the consumer to easily remove them. After a cleaning operation, the debris receptacle  444  is emptied and rinsed along with the brush chamber  422  since these two parts make up the recovery pathway for liquid and debris. The supply tank  451  will also most likely need to be refilled after each operation. 
     As shown in  FIG.  20   , removing the tank assembly  446  from the housing  412  will expose the brushroll  441  and allows the consumer to easily access the brushroll  441 . With the tank assembly  446  removed, the consumer can remove the brushroll  441  by lifting one end of the brushroll upwardly, as indicated by arrow B in  FIG.  20   . The consumer can then carry the brushroll  441 , optionally along with the tank assembly  446 , to a sink for service. The brushroll  441  can be rinsed after a cleaning operation; optionally, the user can manually remove hair and other debris as well. 
     After servicing, the user can easily reassemble the brushroll  441  and the tank assembly  446  back on the housing  412 , optionally after allowing one or both to dry, to prepare the robot  410  for its next cleaning operation. As noted above, while servicing or allowing the serviced components to dry, the housing  412  can be docked and charging. 
     Still referring to  FIG.  20   , in addition to the supply tank  451 , the fluid delivery system can include at least one fluid distributor  452  in fluid communication with the supply tank  451  for depositing a cleaning fluid onto the surface. The fluid distributor  452  shown is a manifold having multiple distributor outlets. Other configuration for the fluid distributor  452  are possible. The fluid distributor  452  can optionally be arranged forwardly of the brush chamber  422  to distribute liquid in front of the brushroll  441 , with reference to the front and rear portions  411 ,  416  of the robot  410 . 
     A pump  453  is provided in the fluid pathway between the supply tank  451  and the fluid distributor  452 , and is coupled to an inlet of the fluid distributor  452  by a first conduit  435 . A second conduit  436  couples the pump  453  to a valve receiver  437  on the housing  412  for fluidly coupling with the supply tank  451  when the tank assembly  446  is seated within the housing  12 . As discussed above, the pump  453  can be driven according to a pulse-width modulation (PWM) signal  28  ( FIG.  1   ). 
     The recovery system can include a recovery pathway through the robot  410  having an air inlet and an air outlet, the debris receptacle  444  for receiving recovered liquid and debris for later disposal, and a suction source  438  in fluid communication with the brush chamber  422  and the debris receptacle  444  for generating a working airstream through the recovery pathway. The suction source  438  can include a vacuum motor located fluidly upstream of the air outlet, and can define a portion of the recovery pathway. Optionally, a pre-motor filter and/or a post-motor filter (not shown) can be provided in the recovery pathway as well. The recovery pathway can further include various conduits, ducts, or tubes for fluid communication between the various components of the vacuum collection system. 
     The suction source  438  can be positioned downstream of the debris receptacle  444  in the recovery pathway. The suction source  438  can include a motor air inlet port  439  for coupling the debris receptacle  444  with the suction source  438 . In other embodiments, the suction source  438  may be located fluidly upstream of the debris receptacle  444 . 
       FIG.  21    is a side elevation cross-sectional view of the robot  410 . The supply tank  451  can define at least one supply reservoir  451 R to store liquid for application, via the pump  453 , to a surface of a floor to be cleaned. The debris receptacle  444  can define at least one receptacle reservoir  444 R and can include a separator  487  for separating liquid and debris from the working airstream. 
     The recovery system of the robot  410  can include a dirty inlet defined by a suction conduit  489 . The dirty inlet or suction conduit  489  can be any type of suction inlet suitable for the purposes described herein, including the collection of debris and liquid from the brushroll  441 . In the illustrated embodiment, the dirty inlet or suction conduit  489  comprises an elongated duct extending from a brush chamber  422  that receives the brushroll  441 , and fluidly couples the brush chamber  422  with the separator  487 . The suction conduit  489  pulls debris and excess liquid from the brushroll  441 . The brush chamber  422  helps define the air flow that goes through the suction conduit  489  and into the debris receptacle  444 . The suction conduit  489  can extend to or be integrally formed with the separator  487 . 
     The debris receptacle  444  can be positioned behind the supply tank  451 , relative to the direction of forward travel  417  of the robot  410 . The brush chamber  422  is located proximate the first end  413 , e.g. proximate the straightedge portion of the housing  412  defining the housing rear  416 . 
     In addition to the drive wheels  471  and caster  474 , the robot  410  can also include one or more additional wheels  482  proximate to the first end  413  of the housing  412 . The additional wheels  482  can, in one example, be utilized to maintain a minimum spacing between the surface to be cleaned and the underside of the housing rear  416 . The caster  374  can be disposed proximate to the second end  415  of the housing  412  to maintain a minimum spacing between the surface to be cleaned and the underside of the housing front  11 . 
       FIG.  22    is a cross-sectional view taken through the brush chamber  422 . The brush chamber  422  substantially surrounds the front, back, and top sides of the brushroll  441  and is defined by the cover  427 . The brush chamber  422  is open at the bottom side of brushroll  441  for engagement of the brushroll  411  with the surface to be cleaned. In the illustrated embodiment, the cover  427  extends over the housing  412  so that the housing  412  is not exposed to the brushroll  441 , and is in particular not exposed to ingested debris and liquid. This prevents debris from collecting on the housing  412 . Rather, debris not ingested into the debris receptacle  444  instead can collect on the cover  427  and in the suction conduit  489  extending to debris receptacle  444 . Since these portions are removable along with the tank assembly  446 , all dirt collected by the robot  410  will be able to be cleaned out at the sink or other waste receptacle. In other words, all surfaces of the robot  410  forming the recovery pathway are removable and easily cleanable. 
     In some embodiments, the brush chamber  422  includes a scraper  496  that removes liquid and debris from the brushroll  441  and keeps it in the brush chamber  422  so that it can be removed by the suction conduit  489 . The scraper  496  can be mounted to or otherwise provided within the brush chamber  422 , and can extend toward the brushroll  441  to interface with a portion of the brushroll  441 . More specifically, the scraper  496  is configured to engage with a forward portion of the brushroll  441 , as defined by the direction of forward travel  417  of the robot  410 . As the brushroll  441  rotates, the scraper  496  can scrape liquid and debris off the brushroll  441 . The scraper  496  can additionally can help redistribute liquid evenly along the length of the brushroll  441 , which can help to reduce streaking on the surface to be cleaned. 
     In one embodiment, the scraper  496  can be an elongated rib, wiper, or blade that generally spans the transverse length of the brushroll  441 . The scraper  496  can have a thin or narrow edge  497  that engages the brushroll  441 , and can optionally taper to the thin or narrow edge  497 . Optionally, the edge  497  can be disposed generally orthogonally to the portion of the brushroll  441  which it engages. Alternatively, the edge  497  can be disposed at an angle to the brushroll  441 . 
     The scraper  496  can be provided on the inside of the cover  427  to project into the brush chamber  422 . The scraper  496  can be formed integrally with the cover  427 , or can be formed separately and attached within the cover  427  using any suitable joining method. 
     Optionally, the scraper  496  can be rigid, i.e. stiff and non-flexible, so the scraper  496  does not yield or flex by engagement with the brushroll  441 . In one example, the scraper  496  can be formed of rigid thermoplastic material, such as poly(methyl methacrylate) (PMMA), polycarbonate, or acrylonitrile butadiene styrene (ABS). Alternatively, the scraper  496  can be pliant, i.e. flexible or resilient, in order to deflect according to the contour of the brushroll  441 . 
     A squeegee  498  can be provided in the brush chamber  422 , rearwardly of the brushroll  441 , to wipe the surface to be cleaned while introducing liquid and dirt into the brush chamber  422  to reduce streaking on the surface to be cleaned, as well as to prevent dry dirt from scattering when the brushroll  441  is rotating during a dry mode of operation. The squeegee  498  can be disposed on the cover  427 , behind the brushroll  441 , and is configured to contact the surface as the robot  410  moves across the surface to be cleaned. Moisture or debris that contacts the squeegee  498  as the robot  410  moves forwardly is entrained in the air flow that goes through the suction conduit  489  and into the debris receptacle  444 . The squeegee  498  can include nubs or ribs on a rearward-facing surface that facilitates liquid and debris passage under the squeegee  498  when the robot  410  is moving in a rearward direction. The opposite side, or forward-facing side, of the squeegee  498  can be a smooth surface that effectively moves surface moisture to trap it within the brush chamber  422  for entrainment in the air flow when the robot  410  is moving in a forward direction. The squeegee  498  can be pliant, i.e. flexible or resilient, in order to bend readily according to the contour of the surface to be cleaned, yet remain undeformed by typical operation of the robot  410 . Optionally, the squeegee  498  can be formed of a resilient polymeric material, such as ethylene propylene diene monomer (EPDM) rubber, polyvinyl chloride (PVC), a rubber copolymer such as nitrile butadiene rubber, or any material known in the art of sufficient rigidity to remain substantially undeformed during a typical operation of the robot  410 . It is noted that  FIG.  22    shows the squeegee  498  unbent, whereas in operation, the squeegee  498  may be bent backward where it engages the floor surface when the robot  410  moves forward in the direction indicated by arrow  417 . 
     Referring to  FIGS.  20  and  23   , when the tank assembly  446  is assembled or reassembled with the housing  412 , one or more connections are made between components of the tank assembly  446  and components of the housing  412 . For example, the supply tank  451  can be connected with the pump  453  and the debris receptacle  444  can be connected with the suction source  438 . 
     The supply tank  451  can further include a valve  458  that is coupled with the valve receiver  437  on the housing  412 . When the tank assembly  446  is seated on the housing  412 , the valve  458  is opened by engagement with the valve receiver  437 , and liquid can flow to the pump  453  via conduit  436 . Alternatively, a direct connection can be made between the valve  458  and pump  453  upon seating of tank assembly  446  on the housing  412 . In still another alternative, various other fluid connectors, conduits, ducts, or tubes can be provided to convey liquid from the supply tank  451  to an inlet of the pump  453 . 
     The debris receptacle  444  can include an air outlet port  499  that is coupled with the air inlet port  439  of the suction source  438 , or otherwise provided on the housing  12  and in fluid communication with the suction source  438 , when the debris receptacle  444  is seated on the housing  412 . The connection made between the air outlet port  499  and the inlet port  439  can be fluid-tight and can include appropriate sealing. Alternatively, various other fluid connectors, conduits, ducts, or tubes can be provided to convey working air from the debris receptacle  444  to an inlet of the suction source  438 . 
     Referring to  FIGS.  24 - 25   , to further aid the user in cleaning out the tank assembly  446 , the tank assembly  446  can optionally include an openable and/or removable lid  500 . The lid  500  can form a top or closure for the debris receptacle  444 , and optionally can include the supply tank  451 . The lid  500  can be secured to a lower portion  501  of the tank assembly  446 . The lower portion  501  can include at least the debris receptacle  444 , or at least the receptacle reservoir  444 R of the debris receptacle  444 . In the illustrated embodiment, the lower portion  501  further includes the cover  427 , brush chamber  422 , the suction conduit  489 , and the separator  487 . In some embodiments, the lid  500  can be openable while remaining attached to the debris receptacle  444  or lower portion  501 , such as by pivoting away from the debris receptacle  444  or lower portion  501  to open the receptacle reservoir  444 R. In other embodiments, the lid  500  can be openable by being fully removable from the debris receptacle  444  or lower portion  501 . 
     A lid latch  502  can secure the lid  500  to a lower portion  501  of the tank assembly  446 . The lid latch  502  includes a latch button  503  that is depressed by the user to release the lid  500  from the lower portion  501 . The lid latch  502  can be any suitable latch, catch, or other mechanical fastener that can join the lid  500  and lower portion  501 , while allowing for the regular separation of the lid  500  from the lower portion  501 , such as a spring-biased latch operable via the latch button  503 . A latch receiver  504  can be provided on the lid  500  to accept the lid latch  502  and secure the lid  500  to the lower portion  501 . 
     Further, the tank assembly  446  can include pivot coupling for movement of the lid  500  about axis C, shown herein as a hook-and-catch mechanism that allows the lid  500  to be fully separated from the lower portion  501 . The hook-and-catch mechanism shown includes a hook  505  on the lower portion  501  that engages with a catch  506  on the lid  500 . Multiple hooks  505  and catches  506  can be provided. Alternatively, the hooks  505  can be provided on the lid  500  and the catches  506  can be provided on the lower portion  501 . In yet another embodiment, the tank assembly  446  can be pivotally mounted to the lower portion  501  about axis C for rotation of the lid  500  between open and closed positions, without full separation of the lid  500  from the lower portion  501 . 
     The lid  500  is shown in a partially-removed state from the lower portion  501  in  FIGS.  24 - 25   . The lid  500  can be removed by pressing the latch button  503  and rotating the lid  500  away from the lower portion  501  about axis C as indicated by arrow D. Once the hooks  505  have cleared the catches  506 , the lid  500  can be separated from the lower portion  501 . After removing the lid  500 , the recovered liquid and dirt can be poured out of the debris receptacle  444 . The entire lower portion  501 , including the internal surface of the debris receptacle  444  and the internal surface of the brush chamber  422  can then be rinsed. 
     As shown in  FIG.  25   , in one embodiment, the separator  487  can be a conduit or duct having a bend for redirecting the working airstream with entrained liquid and/or debris approximately 90 degrees to travel though a separator outlet opening  488  and into the debris receptacle  444 . The liquid and/or debris will strike the various walls of the separator  487  and fall downwardly into the receptacle reservoir  444 R. Other degrees of bend for the separator  487  are possible, such as 90-180 degrees. The liquid and debris collect in the receptacle reservoir  444 R, while the working airstream passes through the air outlet port  499  and to the suction source  438 . The separator  487  can be oriented such that the airflow entering the debris receptacle  444  through the separator outlet opening  488  is positioned away from the air outlet port  499 . 
       FIG.  26    shows an alternate embodiment of the lower portion  501  of the tank assembly  446 , with the lid  500  removed. In some embodiments, the debris receptacle  444  can have a pour spout  507  to aid in conveying liquid and debris out of the receptacle reservoir  444 R. The pour spout  507  can help show the user how to angle the debris receptacle  444  to optimally empty the debris receptacle  444 . The pour spout  507  can be provided at a corner  508  of the debris receptacle  444  disposed away from the brush chamber  422 . Optionally, the pour spout  507  can be covered by the lid  501  ( FIG.  25   ) when the lid  501  is closed and can be exposed to view when the lid  501  is open. 
     Referring to  FIG.  27   , as described above, the suction conduit  489  pulls debris and excess liquid from the brushroll  441 . The brush chamber  422  helps define the air flow that goes through the suction conduit  489  and into the debris receptacle  444 . In the illustrated embodiment, the brush chamber  422  includes lateral ends  509 , with the suction conduit  489  in fluid communication with a portion of the brush chamber  422  between the lateral ends  509 . The suction conduit  489  can in particular fluidly communicate with a middle portion  510  of the brush chamber  422  centered between the lateral ends  509 , such that each lateral end  509  is substantially equidistant from the suction conduit  489 , or can be otherwise located relative to the lateral ends  509 . 
     The brush chamber  422  can taper to become smaller (e.g. shorter) at the lateral ends  509 . The taper helps develop air flow across the entire length of the brushroll  441  and improves recovery. At least an inner surface of an upper wall  511  of the brush chamber  422  can be tapered toward the lateral ends  509 . The upper wall  511  can be smoothly angled toward the suction conduit  489  to substantially continuously increase the height of the brush chamber  422  toward the suction conduit  489 . In the illustrated embodiment, the brush chamber  422  has a height H 1  at one or both of the lateral ends  509  and a height H 2  at the suction conduit  489  which is greater than the height H 1 . With the suction conduit  489  in fluid communication with the middle portion  510  of the brush chamber  422  centered between the lateral ends  509  as shown herein, the height H 2  can be measured at the middle portion  510  of the brush chamber  422  centered between the lateral ends  509 . 
     In an alternative embodiment of the robot  410  shown in  FIGS.  16 - 27   , the tank assembly  446  can combine the debris receptacle  444  and the brush chamber  422  in one unitary assembly or module. The supply tank  451  can be separate from the tank assembly  446  such that it is removable from the housing  412  separately from the tank assembly  446 . The supply tank  451  can be configured such that it is removable from the housing  412  before or after the tank assembly  446 . Alternatively, the supply tank  451  and the tank assembly  446  can have an interlocking mounting arrangement such that the supply tank  451  must be removed prior to removal of the tank assembly  446 , or vice versa. 
     Several alternative embodiments of tank assemblies  446  for the robot  410  are shown in  FIGS.  28 - 30   . The tank assemblies  446  are similar to the tank assembly  446  described above with reference to  FIGS.  16 - 27   , therefore like parts will be identified with like reference numerals, with it being understood that the description of the like parts of the tank assembly  446  and robot  410  applies to the tank assemblies  446  shown in  FIGS.  28 - 30   , except where noted. 
     Referring to  FIG.  28   , the illustrated tank assembly  446  differs by including a fully removable lid  500  that is separate from the supply tank  451 . The lower portion  501  can therefore include the supply tank  451 , in addition to the debris receptacle  444 , cover  427 , and brush chamber  422 . Another difference is that the lid latch  502  securing the lid  500  to the lower portion  501  of the tank assembly  446  is accessible from the top rear side of the tank assembly  446 , and the lid  500  can lift off the lower portion  510  without pivoting. 
     Another difference is that the tank assembly  446  includes a pivoting handle  449  and The handle  449  can pivot against the tank assembly  446  to lie substantially flush with the upper surface of the tank assembly  446  and pivot away upwardly away from the upper surface of the tank assembly  446  for a user to grasp. The pivoting handle  449  can be provided on top of the supply tank  451 , separate from the lid  500 . 
     Referring to  FIG.  29   , the illustrated tank assembly  446  differs from the tank assembly  446  shown in  FIG.  28    by having the supply tank  451  integral with the lid  500  and the pivoting handle  449  on the lid  500 . 
     Referring to  FIG.  30   , the illustrated tank assembly  446  differs from the tank assembly  446  shown in  FIG.  28    by having the lid latch  502  accessible from the top of the tank assembly  446 , at a forward side of the debris receptacle  444 , and by providing finger indentations  512  at a rear side of the debris receptacle  444 . The consumer can grip the handle  449  in one hand and, using their other hand, simultaneously operate the lid latch  502  with their thumb while lifting the lid  500  away from the lower portion  501  to separate the lid  500  from the lower portion  501 . 
     There are several advantages of the present disclosure arising from the various aspects or features of the apparatus, systems, and methods described herein. For example, aspects described above provide an autonomous cleaning robot that sweeps and mops a floor surface in a single pass, including a single pass in a “forward” or “backward” direction. The present disclosure provides a single autonomous floor cleaner that sweeps directly in front of the dusting assembly. This eliminates the need for either two floor cleaning apparatus to completely clean or a single robot that cleans by multiple passes. 
     Another advantage of aspects of the disclosure relates to the consistency and robustness of the liquid distribution system. In contrast to prior art wicking pads, the disclosed pump and spray nozzle provide fluid at a consistent low flowrate that does not degrade over time. The low flowrate of the applied liquid results in a clean floor surface that is substantially dry after contact with the rotating pads of the dusting assembly concludes. The use of a pulse-width modulation signal as described herein can further provide for custom-tailoring of a fluid delivery rate for a variety of floor surfaces, including the adjustment of fluid dwelling times. 
     Yet another advantage of aspects of the disclosure relates to the configuration of the brushroll of the sweeper, the wheels of the drive mechanism and the spinning pads of the dusting assembly. By aligning the outer edges of the wheels, the brushroll and the spinning pads as shown and described above, entrainment of debris in the wheels and spinning pads is reduced thereby improving the driving and cleaning performance of the floor cleaning robot. 
     Still another advantage of aspects of the disclosure relate to the use of a pulse-width modulated signal to drive operation of one or more components such as the fluid pump. Such a modulated signal provides for a reduction in circuit complexity for driving the pump at a variety of flowrates, including at low flow rates, without use of a variable resistor (which can generate undesirable amounts of heat) or use of other, more complex methods of reducing the voltage provided to the pump by the battery pack. 
     Another advantage of aspects of the disclosure relate to the ease of access to one or more tanks within the autonomous floor cleaner, including the unitary or integrated tank assembly being selectively removable from the robot housing. Removal of a single unit can improve the ease of refilling the supply tank or cleaning out the debris receptacle without need of manipulating the entire robot for a cleanout or refill operation. 
     Another advantage of aspects of the disclosure relate to a floor cleaning apparatus including a housing moveable over a surface to be cleaned, a supply tank configured to store a supply of cleaning fluid, and a unitary assembly removably mounted to the housing, wherein the unitary assembly is configured to be selectively detached from the moveable housing, the unitary assembly having a brush chamber, a brushroll located in the brush chamber, at least one fluid distributor, and a debris receptacle fluidly coupled to the brush chamber. The at least one fluid distributor can be in fluid communication with the supply tank and a fluid delivery pump can be provided to control a flow of cleaning fluid from the supply tank to the at least one fluid distributor. 
     Yet another advantage of aspects of the disclosure relates to the configuration of the latch, handle, and pivot coupling for the unitary or integrated tank assembly. In some embodiments disclosed herein, the user provides opposing forces to actuate the latch and lift the tank assembly upwardly away the housing. This helps create a clean breakaway between the two assemblies and keeps the housing in position during removal of the tank assembly. 
     Still another advantage of aspects of the disclosure relate to the configuration of the brush chamber and suction conduit leading to the debris receptacle. In some embodiments disclosed herein, the brush chamber tapers to become smaller in a direction away from the suction conduit, which can help develop air flow across the entire length of the brushroll and improve recovery. 
     While various embodiments illustrated herein show an autonomous floor cleaner or floor cleaning robot, aspects of the invention may be used on other types of surface cleaning apparatus and floor care devices, including, but not limited to, an upright extraction device (e.g., a deep cleaner or carpet cleaner) having a base and an upright body for directing the base across the surface to be cleaned, a canister extraction device having a cleaning implement connected to a wheeled base by a vacuum hose, a portable extraction device adapted to be hand carried by a user for cleaning relatively small areas, or a commercial extractor. Still further, aspects of the invention may also be used on surface cleaning apparatus which include a fluid recovery system and not a fluid supply system, or on surface cleaning apparatus which include a fluid supply system and not a fluid recovery system. Still further, aspects of the invention may also be used on surface cleaning apparatus other than extraction cleaners, such as a steam cleaner or a vacuum cleaner. A steam cleaner generates steam by heating water to boiling for delivery to the surface to be cleaned, either directly or via cleaning pad. Some steam cleaners collect liquid in the pad, or may extract liquid using suction force. A vacuum cleaner typically does not deliver or extract liquid, but rather is used for collecting relatively dry debris (which may include dirt, dust, stains, soil, hair, and other debris) from a surface. 
     While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation. Reasonable variation and modification are possible with the scope of the foregoing disclosure and drawings without departing from the spirit of the invention which, is defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise.