Patent Publication Number: US-2022225854-A1

Title: Robotic cleaner with sweeper and rotating dusting pads

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation of U.S. patent application Ser. No. 16/217,748, filed Dec. 12, 2018, now allowed, 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 entireties. 
    
    
     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 an autonomous floor cleaner. The autonomous floor cleaner includes a sweeper assembly configured for removing debris particles from a surface to be cleaned, the sweeper assembly comprising a brush chamber, and a brushroll rotatably mounted in the brush chamber, a fluid delivery system configured for delivering cleaning fluid, the fluid delivery system comprising a supply tank for storing a supply of cleaning fluid, at least one fluid distributor in fluid communication with the supply tank and configured to deposit cleaning fluid, and a fluid delivery pump configured to control a flow of the cleaning fluid to the at least one fluid distributor, a mopping assembly including at least one pad, and a controller adapted to control the operation of the autonomous floor cleaner to sweep and mop a surface to be cleaned within a single pass of movement of the autonomous floor cleaner. 
     In another aspect, the disclosure relates to a floor cleaning robot. The floor cleaning robot includes a housing, a sweeper assembly provided with the housing and including a brushroll that is selectively rotatable, a mopping assembly provided with the housing, the mopping assembly comprising at least one pad that is selectively moveable, and a fluid delivery system, comprising a supply tank for storing a supply of cleaning fluid, at least one fluid distributor in fluid communication with the supply tank and configured to deposit cleaning fluid, and a fluid delivery pump configured to control a flow of the cleaning fluid to the at least one fluid distributor, and a controller adapted to control the operation of the floor cleaning robot to sweep and mop a surface to be cleaned within a single pass of movement of the floor cleaning robot. 
    
    
     
       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. 
     
    
    
     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 sensor, 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 in to 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. The pump  53  can be driven by pump motor  54  to move liquid at any flowrate useful for a cleaning cycle of operation, including, but not limited to a range of flowrates from 2 to 30 milliliters per second. 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 50%. 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  and can be formed by the bumper  14 . The second end  15  can define a housing rear  16  which is a straight-edge 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 second end  15 , e.g. proximate the straight-edge 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 . It is also contemplated that the first end  13  of the D-shaped housing can include a straight-edge portion as well as a nonlinear portion, such as a curved, bumped, or ribbed portion in non-limiting examples. 
     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  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 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 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. 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. 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 can counter-rotate such that the front edge of each pad is spinning away from the spray nozzle. 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 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  are 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 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 with respect to the wheel housing. 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 drive wheel  71 , 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 . 
     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  10  for a cleanout or refill operation. 
     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.