Patent Publication Number: US-2021169291-A1

Title: Autonomous floor cleaner and docking station

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     The present application claims the benefit of U.S. Provisional Patent Application No. 62/944,602, filed Dec. 6, 2019, which is incorporated herein by reference in its 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 vacuum or sweep dirt (including dust, hair, and other debris) into a collection bin carried on the floor cleaner. Some floor cleaners are further configured to apply and extract liquid for wet cleaning of bare floors, carpets, rugs, and other floor surfaces. 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. Many autonomous floor cleaners need to return to a docking station to recharge their battery and/or empty the collection bin. 
     BRIEF SUMMARY 
     The disclosure relates to an autonomous floor cleaner and to a docking station for an autonomous floor cleaner. Various methods for docking an autonomous floor cleaner with a docking station are described herein. 
     In one aspect, an autonomous floor cleaner includes an autonomously moveable housing, a drive system for autonomously moving the housing over the surface to be cleaned, a controller for controlling the operation of the autonomous floor cleaner, and interchangeable modules for different modes of operation. 
     In another aspect, an autonomous floor cleaner includes an autonomously moveable housing, a drive system for autonomously moving the housing over the surface to be cleaned, a controller for controlling the operation of the autonomous floor cleaner, and one of a lockable member which is engaged by a lock on a docking station, or a lock which engages a lockable member on a docking station. 
     In yet another aspect, a docking station for an autonomous floor cleaner includes one of a lock that engages a lockable member on the autonomous floor cleaner, or a lockable member that is engaged by a lock on the autonomous floor cleaner. 
     In still another aspect, a docking station for an autonomous floor cleaner includes a foldable portion moveable between a docking position and a stowed position. In the docking position, an autonomous floor cleaner can dock with the docking station. In the stowed position, the foldable portion moves to raise the robot off a floor surface. An interlock feature can physically interlock the foldable portion and autonomous floor cleaner together when moving from the docking position to the stowed position. 
     In a further aspect, the disclosure relates to an autonomous floor cleaning system including an autonomous floor cleaner and a docking station. An interlock feature can physically interlock the autonomous floor cleaner to the docking station when docked. 
     In still a further aspect, a method for docking an autonomous floor cleaner with a docking station includes docking the autonomous floor cleaner at the docking station, determining if a predefined locking criterion is met, and interlocking the autonomous floor cleaner with the docking station if the predefined locking criterion is met. 
     In yet a further aspect, a method for docking an autonomous floor cleaner with a docking station includes docking the autonomous floor cleaner at the docking station, interlocking the autonomous floor cleaner with the docking station, determining if a predefined unlocking criterion is met, and unlocking the autonomous floor cleaner from the docking station if the predefined unlocking criterion is met. 
     In still a further aspect, a method for docking an autonomous floor cleaner with a docking station includes docking the autonomous floor cleaner at the docking station, interlocking the autonomous floor cleaner with the docking station, and moving the autonomous floor cleaner to a stowed position. 
     These and other features and advantages of the present disclosure will become apparent from the following description of particular embodiments, when viewed in accordance with the accompanying drawings and appended claims. 
     Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited to the details of operation or to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention may be implemented in various other embodiments and of being practiced or being carried out in alternative ways not expressly disclosed herein. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof. Further, enumeration may be used in the description of various embodiments. Unless otherwise expressly stated, the use of enumeration should not be construed as limiting the invention to any specific order or number of components. Nor should the use of enumeration be construed as excluding from the scope of the invention any additional steps or components that might be combined with or into the enumerated steps or components. Any reference to claim elements as “at least one of X, Y and Z” is meant to include any one of X, Y or Z individually, and any combination of X, Y and Z, for example, X, Y, Z; X, Y; X, Z; and Y, Z. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a schematic view of an autonomous floor cleaning system according to one embodiment of the invention, the system including at least an autonomous floor cleaner, or robot, and a docking station; 
         FIG. 2  is a perspective view of one embodiment of an autonomous floor cleaner or robot for the system of  FIG. 1 ; 
         FIG. 3  is a schematic view of the robot from  FIG. 2 ; 
         FIG. 4  is an enlarged view of portion of the robot, showing the installation of a dry module on the robot; 
         FIG. 5  is an enlarged view of portion of the robot, showing the installation of a wet module on the robot; 
         FIG. 6  is a front perspective view of one embodiment of a docking station for the system of  FIG. 1 ; 
         FIG. 7  is a flow chart showing one embodiment of a method for docking performed by the robot; 
         FIG. 8  is a schematic view of an autonomous floor cleaning system according to another embodiment of the invention, the system including at least an autonomous floor cleaner, or robot, and a docking station, showing the robot docked with the docking station and the docking station in a down position; 
         FIG. 9  is a schematic view of the autonomous floor cleaning system of  FIG. 9 , showing the docking station and robot in a stowed position; and 
         FIG. 10  is a flow chart showing one embodiment of a method for docking performed by the robot. 
     
    
    
     DETAILED DESCRIPTION 
     The disclosure generally relates to the docking of autonomous floor cleaners with docking stations. 
       FIG. 1  is a schematic view of an autonomous floor cleaning system  10  according to one embodiment of the invention. The autonomous floor cleaning system  10  includes an autonomous floor cleaner  12  and a docking station  14  for the autonomous floor cleaner  12 , also referred to herein as a robot. The robot  12  can clean various floor surfaces, including bare floors such as hardwood, tile, and stone, and soft surfaces such as carpets and rugs. Optionally, the system  10  can include an artificial barrier system (not shown) for containing the robot  12  within a user-determined boundary. 
     The robot  12  can be interlocked with the docking station  14 , and can remain locked (preventing separation of the robot  12  from the docking station  14 ) unless certain criteria are present or until a predefined criterion is met. The system  10  includes an interlock feature  16  for physically interlocking the robot  12  and docking station  14 . As shown in  FIG. 1 , the interlock feature  16  can comprise a locking mechanism including a lock  18  on the docking station  14  that selectively engages the robot  12  when the robot  12  is docked, i.e. parked at the docking station  14 . The robot  12  can have a lockable member  20  that is engaged by the lock  18 . In another embodiment, the lock  18  can be provided on the robot  12  and the lockable member  20  can be provided on the docking station  14 . 
     In one embodiment, the lock  18  can comprise a shackle or U-shaped member that loops around from, and back into, a housing of the docking station  14 . The shackle or U-shaped member can loop around or through the lockable member  20  on the robot  12  when the robot  12  is docked. For example, the lockable member  20  can comprise an opening through which the shackle can pass. Other configurations for the lock  18  and lockable member  20  are possible. For example, the lock  18  can comprise an L-shaped member that engages the lockable member  20  on the robot  12 . 
     In one embodiment, the robot  12  can be a deep cleaning robot including a fluid delivery system for storing cleaning fluid and delivering the cleaning fluid to the surface to be cleaned and a fluid recovery system for removing the cleaning fluid and debris from the surface to be cleaned and storing the recovered cleaning fluid and debris. The fluid delivery system may be configured to delivery liquid, steam, mist, or vapor to the surface to be cleaned. 
     In another embodiment, the robot  12  can be a wet mopping or sweeping robot including a fluid delivery system for storing cleaning fluid and delivering the cleaning fluid to the surface to be cleaned and a mopping or sweeping system for removing cleaning fluid and debris from the surface to be cleaned without the use of suction. The fluid delivery system may be configured to delivery liquid, steam, mist, or vapor to the surface to be cleaned. 
     In yet another embodiment, the robot  12  can be a dry vacuum cleaning robot including at least a vacuum collection system for creating a partial vacuum to suck up debris (which may include dirt, dust, soil, hair, and other debris) from a floor surface, and collect the removed debris in a space provided on the robot for later disposal. 
     In still another embodiment, the robot  12  can be a dry sweeping robot including a sweeping system for removing dry debris from the surface to be cleaned without the use of suction, and collect the removed debris in a space provided on the robot for later disposal. 
       FIGS. 2-3  illustrate one embodiment of the robot  12  for the system  10  of  FIG. 1 . It is noted that the robot  12  shown in  FIGS. 2-3  is but one example of an autonomous floor cleaner that is usable with the system  10  and with the docking station  14 , and that other autonomous floor cleaners can be used with the system  10  and docking station  14 . 
     The robot  12  mounts the components various functional systems of the autonomous floor cleaner in an autonomously moveable unit or housing  22 , optionally including components of a collection system  24 , a fluid delivery system  25 , a drive system  26 , a navigation/mapping system  28 , or any combination thereof. A controller  30  is operably coupled with the various functional systems  24 ,  25 ,  26 ,  28  of the robot  12  for controlling the operation of the robot  12 . The controller  30  can be a microcontroller unit (MCU) that contains at least one central processing unit (CPU). 
     As shown, the housing  22  of the robot  12  can be a circular, with a first end  32  and a second end  34 . The first end  32  defines the front of the robot  12  and can optionally comprise a bumper  36 . The second end  34  can define the rear of the robot  12  and optionally comprise a module receiver, as described in further detail below. Other shapes and configurations for the robot  12  are possible, including a D-shaped housing. 
       FIG. 3  is a schematic view of the robot  12  from  FIG. 2 . The collection system  24  can include a working air path through the unit having an air inlet and an air outlet, a suction nozzle  38 , a suction source  40  in fluid communication with the suction nozzle  38  for generating a working air stream, and a collection bin  42  for collecting dirt and/or liquid from the working airstream for later disposal. The suction nozzle  38  can define the air inlet of the working air path, with the inlet opening of the suction nozzle  38  provided on an underside  44  ( FIG. 1 ) of the housing  22  and facing a surface to be cleaned. The suction source  40  can include a vacuum motor  46  carried by the housing  22 , fluidly upstream of the air outlet (not shown), and can define a portion of the working air path. The collection bin  42  can also define a portion of the working air path, and comprise a dirt bin inlet (not shown) in fluid communication with the suction nozzle  38 . Optionally, a separator (not shown) can be formed in a portion of collection bin  42  for separating fluid and entrained dirt from the working airstream. Some non-limiting examples of separators include a cyclone separator, a filter screen, a foam filter, a HEPA filter, a filter bag, or combinations thereof. Optionally, a pre-motor filter and/or a post-motor filter (not shown) can be provided in the working air path as well. The working air path can further include various conduits, ducts, or tubes for fluid communication between the various components of the collection system  24 . The vacuum motor  46  can be positioned fluidly downstream or fluidly upstream of the collection bin  42  in the working air path. 
     The collection system  24  can also include at least one agitator for agitating the surface to be cleaned. The agitator can be in the form of a brushroll  48  mounted for rotation about a substantially horizontal axis, relative to the surface over which the robot  12  moves. A drive assembly including a brush motor  50  can be provided within the robot  12  to drive the brushroll  48 . 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. 
     The suction nozzle  38  can be positioned in close proximity to the brushroll  48  to collect liquid and debris directly from the brushroll  48 . In other embodiments, the suction nozzle  38  can be positioned to confront the surface to be cleaned to remove liquid and debris from the surface, rather than the brushroll  48 . 
     Referring to  FIG. 2 , optionally, the robot  12  includes at least one edge brush  94  that can clean hard-to reach spaces such as along edges and in corners of a room, including edges or corners created by walls, baseboards, cabinetry, furniture, etc. The edge brush  94  can sweep debris under the housing  22  and toward the suction nozzle  38 . The edge brush  94  can comprise one or more different agitation or cleaning elements configured to brush, sweep, dust, mop, or otherwise move debris on the surface to be cleaned. Some non-limiting examples of cleaning elements for the edge cleaning brush comprise blades, bristles, paddles, blades, flaps, microfiber material, fabric, dusting pads, and the like. 
     Referring to  FIG. 3 , a drive assembly including an edge brush motor  96  can be provided within the robot  12  to drive the edge brush  94 . The brush motor  96  is configured to drive at least a portion of the edge brush  94  about a substantially vertical rotational axis, relative to the surface to be cleaned. 
     In another embodiment, the collection system  24  can be configured as a sweeping system that removes dry debris from the floor surface without the use of suction. In this case, the suction source  40  may not be provided. 
     The fluid delivery system  25  can include a supply tank  52  for storing a supply of cleaning fluid and at least one fluid distributor  54  in fluid communication with the supply tank  52  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  54  can be one or more spray nozzles provided on the housing  22  with an orifice of sufficient size such that debris does not readily clog the nozzle. Alternatively, the fluid distributor  54  can be a manifold having multiple distributor outlets. 
     A pump  56  can be provided in the fluid pathway between the supply tank  52  and the at least one fluid distributor  54  to control the flow of fluid to the at least one fluid distributor  54 . The pump  56  can be driven by a pump motor  58  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  25 , such as a heater  60  or one or more fluid control and mixing valves. The heater  60  can be configured, for example, to warm up the cleaning fluid before it is applied to the surface. In one embodiment, the heater  60  can be an in-line fluid heater between the supply tank  52  and the distributor  54 . In another example, the heater  60  can be a steam generating assembly. The steam assembly is in fluid communication with the supply tank  52  such that some or all the liquid applied to the floor surface is heated to vapor. 
     The drive system  26  can include drive wheels  64  for driving the robot  12  across a surface to be cleaned. The drive wheels  64  can be operated by a common wheel motor  66  or individual wheel motors  66  coupled with the drive wheels  64  by a transmission, which may include a gear train assembly or another suitable transmission. The drive system  26  can receive inputs from the controller  30  for driving the robot  12  across a floor, based on inputs from the navigation/mapping system  28  for the autonomous mode of operation or based on inputs from a smartphone, tablet, or other remote device for an optional manual mode of operation. The drive wheels  64  can be driven in a forward or reverse direction to move the unit forwardly or rearwardly. Furthermore, the drive wheels  64  can be operated simultaneously at the same rotational speed for linear motion or independently at different rotational speeds to turn the robot  12  in a desired direction. While the drive system  26  is shown herein as including rotating wheels  64 , it is understood that the drive system  26  can comprise alternative traction devices for moving the robot  12  across a surface to be cleaned. 
     In addition to the drive wheels  64  or other traction devices, the robot  12  can include one or more additional wheels  62  that support the housing  22 , such as a castor wheel at a center, rear portion of the underside  44  of the housing  22 , as shown in  FIG. 1 . 
     The controller  30  can receive input from the navigation/mapping system  28  or from a remote device such as a smartphone (not shown) for directing the robot  12  over the surface to be cleaned. The navigation/mapping system  28  can include a memory  68  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  12 , etc. For example, wheel encoders  70  can be placed on the drive shafts of the drive wheels  64  and configured to measure a distance traveled by the robot  12 . The distance measurement can be provided as input to the controller  30 . 
     In an autonomous mode of operation, the robot  12  can be configured to travel in any pattern useful for cleaning or sanitizing including boustrophedon or alternating rows (that is, the robot  12  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 the optional manual mode of operation, movement of the robot  12  can be controlled using a mobile device such as a smartphone or tablet. 
     The robot  10  can include any number of motors useful for performing locomotion and cleaning and any number of motor drivers for controlling the motors. In the embodiment shown, a vacuum motor driver  72 , a brushroll motor 6  driver  74 , a wheel motor driver  76 , a pump motor driver  78 , and an edge brush motor driver  79  can be provided for controlling the vacuum motor  46 , brush motor  50 , wheel motors  66 , pump motor  58 , and edge brush motor  96 , respectively. The motor drivers can act as an interface between the controller  30  and their respective motors. The motor drivers can be an integrated circuit chip (IC). It is also contemplated that a single wheel motor driver  76  can control multiple wheel motors  66  simultaneously. 
     The motor drivers can be electrically coupled to a battery management system  80  that includes a rechargeable battery  81 , which may comprise battery pack. In one example, the battery pack can comprise a plurality of can include lithium ion batteries. Batteries with other cell chemistries, such as nickel metal hydride and nickel cadmium, are also possible. Electrical contacts or charging contacts  82  for the battery  81  can be provided on an exterior surface of the robot  12 . In one embodiment, the charging contacts  82  are provided on the underside  44  of the robot  12 . In another embodiment, the charging contacts  82  are provided on the second end or rear side  34  of the robot  12 . 
     In one embodiment, positive and negative charging contacts  82  are utilized to detect a completed circuit when the robot  12  docks with the docking station  14 . In other embodiments, a single charging contact  82  or more than two charging contacts  82  may be utilized. An additional charging contact would provide redundancy in the event that one of the other charging contacts becomes dirty, obstructed, or damaged. In still other embodiments of the robot  12 , additional contacts may be used to transmit data and information between the robot  12  and docking station  14 . 
     The controller  30  is further operably coupled with a user interface (UI)  84  on the robot  12  for receiving inputs from a user. The UI  84  can be used to select an operation cycle for the robot  12  or otherwise control the operation of the robot  12 . The UI  84  can have a display  86 , such as an LED display, for providing visual notifications to the user. A display driver  88  can be provided for controlling the display  86 , and acts as an interface between the controller  30  and the display  86 . The display driver  88  may be an IC. The robot  12  can be provided with a speaker (not shown) for providing audible notifications to the user. 
     The UI  84  can further have one or more switches  90  that are actuated by the user to provide input to the controller  30  to control the operation of various components of the robot  12 . A switch driver  92  can be provided for controlling the switch  90 , and acts as an interface between the controller  30  and the switch  90 . 
     The robot  12  can 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  12  by gestures. For example, the user can wave their hand in front of the camera to instruct the robot  12  to stop or move away. In one embodiment, the user can execute a gesture in front of the camera that instructs the robot  12  to dock with the docking station  14 . 
     The robot  12  can comprise an on-board Wi-Fi connection that is configured to allow the robot  12  to be controlled remotely through a mobile device, such as a smartphone or tablet, or via a voice-controlled remote device such as an Amazon Echo® or Amazon Echo Dot® having the Amazon Alexa® cloud-based voice service, or a Google Home® or Google Home Mini® having Google Assistant. For example, a user with a smart speaker device can speak an instruction, such as “Alexa, ask [robot] to start cleaning,” and via the Wi-Fi and/or Internet connectivity, the robot  12  can begin a cleaning cycle of operation. 
     A smart device application for the robot  12  that is executed on a mobile or remote device can include further command and control features including, but not limited to, scheduling features to enable a user to select when the robot  12  will conduct cleaning. Other features of the smart device application cam include a display of the robot&#39;s cleaning history, a landing page with current blogs and support videos related to the robot  12 , and controls to automatically reorder accessories for the robot  10  when needed. The smart device application can also be configured to provide detailed notifications relating diagnostics, error warnings, and other information directly to the user. 
     The controller  30  can be operably coupled with various sensors on board the robot  12  for receiving input about the environment and from the docking station  14 , and can use the sensor input to control the operation of the robot  12 . The sensors can detect features of the surrounding environment of the robot  10  including, but not limited to, the docking station  14 , walls, floors, chair legs, table legs, footstools, pets, consumers, and other obstacles. The sensor input can further be stored in the memory  68  or used to develop maps by the navigation/mapping system  28 . Some exemplary sensors are illustrated in  FIG. 3 , 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  12  can include one or more distance sensor(s)  100  for position/proximity sensing. The distance sensors  100  can be mounted to the housing  22  of the robot  12 , such as in the front of the housing  22  to determine the distance to obstacles in front of the robot  12 . Input from the distance sensors  100  can be used to slow down, turn, and/or adjust the course of the robot  12  when objects are detected. In one embodiment, the robot  12  can dock with the docking station  14  based on input from the distance sensors  100 . 
     The robot  12  may include one or more of a bump sensor  102 , a wall following sensor  104 , a cliff sensor  106 , an inertial measurement unit (IMU)  108 , a lift-up sensor  110 , a bin or tank sensor  112 , or a floor condition sensor  114 , including any combination or multiples thereof. 
     The bump sensor  102  determines front or side impacts to the robot  12 , and may be integrated with the housing  22 , such as with a bumper  36  ( FIG. 2 ). Output signals from the bump sensors  102  provide inputs to the controller  30  for selecting an obstacle avoidance algorithm. 
     The wall following sensor  104  (also known as a side wall sensor) can be located near the side of the housing  22  and can include a side-facing position sensor that provides distance feedback and controls the robot  12  so that the robot  12  can follow near a wall without contacting the wall. The wall following sensor  104  can be an optical, mechanical, or ultrasonic sensor, including a reflective or time-of-flight sensor. In another embodiment, a wall following sensor is not provided, and the distance sensors  100  are instead used as wall following sensors. 
     The cliff sensor  106  can be a ground-facing position sensor that provides distance feedback so that the robot  12  can avoid excessive drops down stairwells, ledges, etc. The cliff sensor  106  can be an optical, mechanical, or ultrasonic sensor, including a reflective or time-of-flight sensor. 
     The IMU  108  can measure and report the robot&#39;s acceleration, angular rate, or magnetic field surrounding the robot  12 , using a combination of at least one accelerometer, gyroscope, and, optionally, magnetometer or compass. The IMU  108  can be an integrated inertial sensor located on the controller  30  and can be a nine-axis gyroscope or accelerometer to sense linear, rotational or magnetic field acceleration. The IMU  108  can use acceleration input data to calculate and communicate change in velocity and pose to the controller  30  for navigating the robot  12  around the surface to be cleaned. 
     The lift-up sensor  110  can detect when the robot  12  is lifted off the surface to be cleaned e.g. if a user picks up the robot  12 . This information is provided as an input to the controller  30 , which can halt operation of the motors  46 ,  50 ,  58 ,  66  in response to a detected lift-up event. The lift-up sensor  110  may also detect when the robot  12  is in contact with the surface to be cleaned, such as when the user places the robot  12  back on the ground. Upon such input, the controller  30  may resume operation. 
     The robot  12  can optionally include one or more sensors  112  for detecting a characteristic or status of the collection bin  42  or supply tank  52 . In one example, one or more pressure sensors for detecting the weight of the collection bin  42  or supply tank  52  can be provided. In another example, one or more magnetic sensors for detecting the presence of the collection bin  42  or supply tank  52  can be provided. This information is provided as an input to the controller  30 , which may prevent operation of the robot  12  until the collection bin  42  is emptied, the supply tank  52  is filled, or either is properly installed on the housing  22 , in non-limiting examples. The controller  30  may also direct the user interface  84  to provide a notification to the user that the collection bin  42  is full, the supply tank  52  is empty, or that neither is installed. 
     The floor condition sensor  114  detects a condition of the surface to be cleaned. For example, the robot  12  can be provided with an infrared (IR) dirt sensor, a stain sensor, an odor sensor, or a wet mess sensor. The floor condition sensor  114  provides input to the controller  30  that may direct operation of the robot  12  based on the condition of the surface to be cleaned, such as by selecting or modifying a cleaning cycle. Optionally, the floor condition sensor  114  can also provide input for display on a smartphone. 
     The robot  12  can have at least one receiver  116  to detect signals emitted from the docking station  14 . In one embodiment, a docking signal from the docking station  14  can be transmitted to the robot  12  and received by the receiver  116  to guide the robot  12  to the docking station  14 . 
     The robot  12  can operate in one of a set of modes. The modes can include at least a dry mode and a wet mode. During the wet mode of operation, liquid is applied to the floor surface. During the dry mode of operation, no liquid is applied to the floor surface. 
     In one embodiment, the robot  12  has interchangeable modules  120 ,  122  for the dry mode and the wet mode, respectively. Each module  120 ,  122  can be installed and removed from the housing  22  as a unit. The housing  22  of the robot  12  includes a module receiver  124  in which the modules  120 ,  122  can be installed, one at a time. In the embodiment shown, the module receiver  124  can be located at the second end  34  of the housing  22 , for installation of removal of modules through the rear of the robot  12 . Other locations for the module receiver  124  are possible. 
     The modules  120 ,  122  can be removable from the module receiver  124  while the robot  12  is docked and interlocked with the docking station  14 . In one embodiment, the interlock feature  16  can be configured to physically interlock the housing  22  of the robot  12  with the docking station, and not the module  120 ,  122 . For example, the lockable member  20  can be disposed in a location on the housing  22  where the engagement by the lock  18  does not interfere with the removal of the module  120 ,  122 . In another embodiment, the lock  18  is provided on the robot  12  and the lockable member  20  is provided on the docking station  14 , the lock  18  can be disposed in a location on the housing  22  where the movement of the lock  18  and engagement with the lockable member  20  does not interfere with the removal of the module  120 ,  122 . In either case, when the robot  12  is docked and interlocked with the docking station  14 , the modules  120 ,  122  can be removed from the housing  22  for emptying or refilling, while the housing  22  remains locked to the docking station  14 . 
     Referring to  FIG. 4 , the dry mode module or dry module  120  can include the collection bin  42 . The dry module  120  can optionally include a latch  126  or other mechanism for securing the module  120  within the receiver  124 . The dry module  120  is inserted into the receiver  124  for operation of the robot  12  in the dry mode. During the dry mode of operation, a partial vacuum can be generated at the suction nozzle  38  by the suction source  40  to collect liquid and/or debris in the collection bin  42 . During the dry mode of operation, the brushroll  48  and/or edge brush  94  can be rotated. In the embodiment shown, the brushroll  48  and edge brush  94  remain on the housing  22  in both modes. In an alternative embodiment, one or both of the brushroll  48  and edge brush  94  can be included on the dry module  120 . 
     The wet mode module or wet module  122  can include the supply tank  52 . The wet module  122  can optionally include a mopping assembly  128 . The mopping assembly  128  can include at least one mop pad  130  for mopping the floor surface. The mop pad  130  can comprise one or more different agitation or cleaning elements configured to mop the surface to be cleaned. Some non-limiting examples of cleaning elements for the mop pad  130  comprise a microfiber pad or a wet scrubbing pad. The mop pad  130  can be disposable or reusable. In the embodiment shown, the mopping assembly  128  includes two mop pad  130 . 
     Referring to  FIG. 3 , a drive assembly including at least one mop pad motor  132  can be provided within the wet module  122  to drive the at least one mop pad  130 . In the embodiment shown with multiple mop pads  130 , the mop pad  130  can be operated by a common motor  132  or individual motors  132 . The mop pad motor  132  is configured to drive at least a portion of the mop pad  130  about a substantially vertical rotational axis, relative to the surface to be cleaned. A mop pad motor driver  134  can be provided for controlling each mop pad motor  132 . The motor driver  134  can act as an interface between the controller  30  and its respective motor. The motor driver  134  can be an integrated circuit chip (IC). It is also contemplated that a single mop pad motor driver  134  can control multiple mop pad motors  132  simultaneously. 
     The wet module  122  can optionally include a latch  136  or other mechanism for securing the module  122  within the receiver  124 . The wet module  122  is inserted into the receiver  124  for operation of the robot  12  in the wet mode. 
     During the wet mode of operation, liquid from the supply tank  52  is applied to the floor surface and the mop pads  130  can be rotated. In one embodiment, the mopping assembly  128  can remove cleaning fluid and debris from the surface to be cleaned without the use of suction. Cleaning fluid and debris can be collected by the mop pads  130 . In another embodiment, during the wet mode, a partial vacuum can be generated at the suction nozzle  38  by the suction source  40  to collect liquid and/or debris in a space onboard the robot  12 . In one example, the wet module  122  can include a collection chamber for recovered liquid and/or debris. 
     The module receiver  124  can comprise suitable connections for establishing the flow of air, debris, cleaning fluid, and power, as required, between the modules and components within the housing  22 . For example, the module receiver  124  can include suitable connections for establishing the flow of air and debris between the suction nozzle  38 , suction source  40 , and collection bin  42 , i.e. through the working air path of the collection system  24 . The module receiver  124  can include suitable connections for establishing the flow of cleaning fluid between the supply tank  52  and the distributor  54 , i.e. through the supply path of the delivery system  25 . The module receiver  124  can further include suitable connections for establishing the flow of power between the battery  81  and the mop pad motor or motors  132  of the wet module  122 . 
       FIG. 6  illustrates one embodiment of the docking station  14  for the system  10  of  FIG. 1 . It is noted that the docking station  14  shown in  FIG. 6  is but one example of a dock that is usable with the system  10  and with the robot  12 , and that other docks can be used with the system  10  and robot  12 . 
     The docking station  14  can recharge a power supply of the robot  12  (e.g. battery  81 ). In one example, the docking station  14  can be connected to a household power supply, such as an A/C power outlet, and can include a converter  142  for converting the AC voltage into DC voltage for recharging the power supply on-board the robot  12 . 
     The docking station  14  can include various sensors and emitters (not shown) for monitoring a status of the robot  12 , enabling auto-docking functionality, communicating with the robot  12 , as well as features for network and/or Bluetooth connectivity. 
     In another embodiment, in addition to or as an alternative to recharging the robot  12 , the docking station  14  can perform service, maintenance, or diagnostic checks for the robot  12 . For example, the docking station  14  can be configured to automatically empty the collection bin  42  and/or automatically fill or refill the supply tank  52 . To perform service, maintenance, and/or diagnostic checks for the robot  12 , the docking station  14  may first engage the lock  18  to physically interlock the robot  12  and docking station  14 , and then proceed with performing at least one service, maintenance, and/or diagnostic check for the robot  12 . 
     The docking station  14  includes a housing  144  and electrical contacts or charging contacts  146  disposed on the housing  144  that are adapted to mate with the charging contacts  82  on the exterior surface of the robot  12  to charge the battery  81  of the robot (see  FIG. 3 ). 
     The housing  144  can have a base plate  148  and a backstop  150 . The base plate  148  can extend generally horizontally to be disposed on the floor support. The backstop  138  is generally perpendicular to the floor surface on which the base plate  148  rests. Other shapes and configurations for the housing  144  are possible. 
     The robot  12  can dock by driving at least partially onto the base plate  148 , optionally until the robot  12  meets the backstop  150 . The charging contacts  146  of the docking station  14  can be located on the base plate  148 , allowing them to contact corresponding contacts  82  on the underside  44  of the robot  12  when the robot  12  drives onto the base plate  148 . Alternatively, the charging contacts  146  can be provided on the backstop  150 , or other portion of the housing  144 . 
     In one embodiment, positive and negative charging contacts  146  are utilized to detect a completed circuit when the robot  12  docks with the docking station  14 . In other embodiments, a single charging contact  146  or more than two charging contacts  146  may be utilized. An additional charging contact would provide redundancy in the event that one of the other charging contacts becomes dirty, obstructed, or damaged. In still other embodiments of the docking station  14 , additional contacts may be used to transmit data and information between the robot  12  and docking station  14 . 
     The docking station  14  can include a portion of the interlock feature  16  for physically interlocking the robot  12  and docking station  14 . As shown in  FIG. 1 , the docking station  14  can comprise the lock  18 , which can be provided on the base plate  148 . The lockable member  20  that is engaged by the lock  18  can be provided on the underside  44  of the robot  12 . In another embodiment, the lock  18  can be provided on the underside  44  of the robot  12  and the lockable member  20  can be provided on the base plate  148  of the docking station  14 . In yet another embodiment, the lock  18  can be provided on the backstop  150  and the lockable member  20  can be provided on a lateral side of the robot  12 . In still another embodiment, the lock  18  can be provided on a lateral side of the robot  12  and the lockable member  20  can be provided on the backstop  150 . 
     In one embodiment, when the wet module  122  is installed, and the robot  12  is docked with the docking station  14 , the interlock  16  secures the robot  12  to the docking station  14  until a predefined criterion is met. The predefined criteria may be the removal of the wet module  122  from the housing  22  and the installation of the dry module  120 . This can prevent a user from trying to fill the supply tank  52  under a faucet while the wet module  122  is installed on the robot  12 , which can allow water spill into the interior of the robot  12 . Instead, the interlock  16  encourages the user to separate the wet module  122  from the robot  12  before refilling by preventing separation of the robot  12  from the docking station  14  with the wet module  122  still installed. When the wet module  122  is removed and the dry module  120  installed in its place, the lock  18  can disengage from the lockable member  20 , thereby permitting the robot  12  to be separated from the docking station  14 . Optionally, if the dry module  120  is installed when the robot  12  docks with the docking station  14 , the lock  18  does not engage the lockable member  20 . 
     An activating switch  152  for controlling the lock  18  can be provided, and can be operable to move between an on and off position. When the activating switch  152  is on, the lock  18  is engaged. When the activating switch  152  is off, the lock  18  is disengaged. The activating switch is configured to be actuated, i.e. moved to the on position, when the robot  12  docks with the docking station  14 . 
     In one embodiment, the activating switch  152  can comprise an optical switch on the docking station  14  that is occluded by the wet module  122 , and not by the dry module  120 , to indicate that the robot  12  is present with the wet module  122 . When the robot  12  docks with the dry module  120 , the optical switch is not occluded, and the lock  18  does not engage. 
     In another embodiment, the activating switch  152  can comprise a mechanical switch on the docking station  14  that is physically engaged by the robot  12  to move to the on position. In still another embodiment, the wet module  122 , and not by the dry module  120 , can comprise a switch actuator that physically engages the activating switch  152  when the robot  12  docks with the docking station  14 . In such an embodiment, when the robot  12  docks with the dry module  120 , the mechanical activating switch  152  is not physically engaged, and the lock  18  does not engage. 
     Optionally, an override control can be provided on the robot  12 , the docking station  14 , and/or on a smart device application executed on a mobile or remote device for disengaging the interlock  16  even when the predefined criteria is not met. 
       FIG. 7  is a flow chart showing one embodiment of a method  200  for docking the robot  12  at the docking station  14 . The sequence of steps discussed is for illustrative purposes only and is not meant to limit the method in any way as it is understood that the steps may proceed in a different logical order, additional or intervening steps may be included, or described steps may be divided into multiple steps, without detracting from the invention. 
     At step  202 , the robot  12  docks with the docking station  14 . At step  204 , it is determined whether the wet module  122  is present on the robot  12 . If the wet module  122  is not present, the method  200  proceeds to step  206  and the interlock  16  remains disengaged. If the wet module  122  is present, the method  200  proceeds to step  208 , and the interlock  16  engages. Subsequently, if the dry module  120  is swapped for the wet module  122 , and it is determined that the dry module  120  is now present on the robot  12  at step  210 , the interlock  15  is disengaged at step  212 . 
       FIGS. 8-9  are schematic views of an autonomous floor cleaning system  10  having an alternate embodiment of the docking station  14  according to another embodiment of the invention. The docking station  14  can fold down to receive the robot  12  as shown in  FIG. 8 , and can fold up to move the robot  12  to a substantially vertical position, or alternatively to another off-the-floor position, as shown in  FIG. 9 . The interlock feature  16  (shown in phantom line) can physically interlock the robot  12  and docking station  14  to lock the robot in place when moving from the down or docking position, an example of which is shown in  FIG. 8 , to the stowed position, an example of which is shown in  FIG. 9 . The foldable docking station  14  and interlock  16  improve the stowability of the docked robot  12 . The docking station  14  can also fold up when the robot  12  is not docked for a more compact profile, which can allow the robot  12  to clean more floor space around the docking station  14 . 
     In one embodiment, the base plate  148  of the docking station  14  can rotate up for storage. The base plate  148  of the docking station  14  can fold up and down automatically or manually. If automatic, the docking station  14  can rotate down and release the robot  12  for cleaning. Cleaning can be initiated manually by the user, or automatically during a scheduled cleaning time. The robot  12  docks with the docking station  14  upon a return-to-dock event, such as when cleaning is complete, when the battery  81  requires charging, the collection bin  42  (if present) requires emptying, and/or the supply tank (if present) requires filling, and the base plate  148  rotates up to stow the robot  12  until the next cleaning, until the battery  81  is recharged, the collection bin  42  (if present) is emptied, and/or the supply tank (if present) is filled. 
       FIG. 10  is a flow chart showing one embodiment of a method  300  for docking the robot  12  at the docking station  14  described with respect to  FIGS. 8-9 . The sequence of steps discussed is for illustrative purposes only and is not meant to limit the method in any way as it is understood that the steps may proceed in a different logical order, additional or intervening steps may be included, or described steps may be divided into multiple steps, without detracting from the invention. 
     At step  302 , a return-to dock event occurs. Examples of return-to-dock events include, but are not limited to, the completion of a cleaning cycle of operation, the battery  81  being below a predetermined level, a user commanding the robot  12  to dock (e.g. by pressing a dock or home button on the robot  12  or on a mobile device), the collection bin  42  being full, or the supply tank  52  being empty. At step  304 , if necessary, the docking station  14  moves to the down or docking position. At step  306 , the robot  12  docks with the docking station  14 . At step  308 , the interlock  16  engages. At step  310 , the docking station  14 , along with the robot  12 , moves to the stowed position. This moves the robot  12  off the floor surface. 
     Optionally, upon competition of the return-to dock event at step  312 , the docking station  14  can move to the down or docking position, lowering the robot  12  back to the floor surface. At step  316 , the interlock  16  can disengage. The robot  12  is now free to leave the docking station  14 . 
     Examples of a completion of a return-to-dock event for step  312  include, but are not limited to, the start of a cleaning cycle of operation, the battery  81  being charged, a user commanding the robot  12  to un-dock, the collection bin  42  being emptied, or the supply tank  52  being filled. 
     Any embodiment of the docking station  14  disclosed herein can include a dirt dump feature that removes debris from the robot  12  into a larger container with a plastic bag. 
     Any embodiment of the docking station  14  disclosed herein can include drain plumbing for that removes liquid from the robot  12  into a larger container or household drain line. 
     Any embodiment of the docking station  14  disclosed herein can include a supply feature for supplying cleaning fluid to the robot  12 . 
     To the extent not already described, the different features and structures of the various embodiments of the invention, may be used in combination with each other as desired, or may be used separately. That one autonomous floor cleaning system, robot, or docking station is illustrated herein as having the described features does not mean that all of these features must be used in combination, but rather done so here for brevity of description. Any of the disclosed docking stations may be provided independently of any of the disclosed robots, and vice versa. Further, while multiple methods are disclosed herein, one of the disclosed methods may be performed independently, or more than one of the disclosed methods, including any combination of methods disclosed herein may be performed by one robot or docking station. Thus, the various features of the different embodiments may be mixed and matched in various cleaning apparatus configurations as desired to form new embodiments, whether or not the new embodiments are expressly described. 
     The above description relates to general and specific embodiments of the disclosure. However, various alterations and changes can be made without departing from the spirit and broader aspects of the disclosure as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. As such, this disclosure is presented for illustrative purposes and should not be interpreted as an exhaustive description of all embodiments of the disclosure or to limit the scope of the claims to the specific elements illustrated or described in connection with these embodiments. Any reference to elements in the singular, for example, using the articles “a,” “an,” “the,” or “said,” is not to be construed as limiting the element to the singular. 
     Likewise, it is also to be understood that the appended claims are not limited to express and particular components or methods described in the detailed description, which may vary between particular embodiments that fall within the scope of the appended claims. With respect to any Markush groups relied upon herein for describing particular features or aspects of various embodiments, different, special, and/or unexpected results may be obtained from each member of the respective Markush group independent from all other Markush members. Each member of a Markush group may be relied upon individually and or in combination and provides adequate support for specific embodiments within the scope of the appended claims.