Patent Publication Number: US-2021186282-A1

Title: Robotic cleaner

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of U.S. Provisional Application Ser. No. 62/945,684 filed on Dec. 9, 2019, entitled Robotic Cleaner with Edge Cleaning, which is fully incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to autonomous devices and, more particularly to, robotic cleaners. 
     BACKGROUND INFORMATION 
     Robotic cleaners have become an increasingly popular appliance for automated cleaning applications. In particular, robotic vacuum cleaners are used to vacuum surfaces while moving around surfaces with little or no user interaction. Robotic vacuum cleaners include a suction system. Robotic vacuum cleaners may also include one or more cleaning implements such as one or more agitators (e.g., rotating brush rolls) and/or one or more side brushes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features and advantages will be better understood by reading the following detailed description, taken together with the drawings wherein: 
         FIG. 1  is a perspective view of a robotic cleaner, consistent with embodiments of the present disclosure. 
         FIG. 2  is a bottom view of an example of the robotic cleaner shown in  FIG. 1 , consistent with embodiments of the present disclosure. 
         FIG. 3  is a perspective view of another example of the robotic cleaner of  FIG. 1 , consistent with embodiments of the present disclosure. 
         FIG. 4A  is another perspective view of the robotic cleaner of the robotic cleaner of  FIG. 3  having projections, consistent with embodiments of the present disclosure. 
         FIG. 4B  is a magnified view of a portion of the robotic cleaner of  FIG. 4A , illustrating the projections in greater detail, consistent with embodiments of the present disclosure. 
         FIG. 4C  is a magnified cross-sectional view illustrating an example of one of the projections of  FIG. 4B  in greater detail, consistent with embodiments of the present disclosure. 
         FIG. 5  is a top perspective view of the robotic cleaner of  FIG. 4A , consistent with embodiments of the present disclosure. 
         FIG. 6  is a cross-sectional view of a robotic cleaner, consistent with embodiments of the present disclosure. 
         FIG. 7  is a bottom perspective view of the robotic cleaner of  FIG. 6 , consistent with embodiments of the present disclosure. 
         FIG. 8  is another bottom perspective view of the robotic cleaner of  FIG. 6 , consistent with embodiments of the present disclosure. 
         FIG. 9  is a front perspective view of the robotic cleaner of  FIG. 6 , consistent with embodiments of the present disclosure. 
         FIG. 10  is another front perspective view of the robotic cleaner of  FIG. 6 , consistent with embodiments of the present disclosure. 
         FIG. 11  is a rear view of a robotic cleaner, consistent with embodiments of the present disclosure. 
         FIG. 12  is a front view of the robotic cleaner of  FIG. 11 , consistent with embodiments of the present disclosure. 
         FIG. 13  is a right view of the robotic cleaner of  FIG. 11 , consistent with embodiments of the present disclosure. 
         FIG. 14  is a left view of the robotic cleaner of  FIG. 11 , consistent with embodiments of the present disclosure. 
         FIG. 15  is a top view of the robotic cleaner of  FIG. 11 , consistent with embodiments of the present disclosure. 
         FIG. 16  is a bottom view of the robotic cleaner of  FIG. 11 , consistent with embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure is generally directed to a robotic cleaner. The robotic cleaner includes a housing and an agitator (e.g., a brush roll). The agitator may be configured to rotate about an agitator rotation axis that extends substantially parallel to a front side of the housing and to a surface to be cleaned (e.g., a floor). In some instances, one or more projections may extend from the housing. The one or more projections may include one or more cliff sensors that are configured to detect a non-traversable drop-off (or cliff) in the surface to be cleaned. 
     Additionally, or alternatively, in some instances, the robotic cleaner may include one or more spiral brushes. The one or more spiral brushes rotate about a spiral brush rotation axis that extends substantially parallel to the surface to be cleaned and transverse to (e.g., perpendicular to) the agitator rotation axis. Additionally, or alternatively, in some instances, the agitator may be configured to move along one or more of a drop axis and/or a forward bump axis. Movement along the drop axis is indicative of a presence of a non-traversable drop-off in the surface to be cleaned (or cliff) and movement along the forward bump axis is indicative of the presence of an obstacle. 
     As used herein, the terms “above” and “below” are used relative to an orientation of the cleaning apparatus on a surface to be cleaned and the terms “front” and “back” are used relative to a direction that the cleaning apparatus moves on a surface being cleaned during normal cleaning operations. As used herein, the term “leading” refers to a position in front of at least another component but does not necessarily mean in front of all other components. 
       FIG. 1  shows a perspective schematic view of an example of a robotic cleaner  101 , consistent with embodiments of the present disclosure. Although a particular embodiment of a robotic cleaner  101  is shown and described herein, the concepts of the present disclosure may apply to other types of robotic cleaners. 
     As shown, the robotic cleaner  101  includes a housing  100  having a front side  108 , a back side  109  that is opposite the front side  108 , a left side  112 , a right side  114  that is opposite the left side  112 , an upper side (or top surface)  110 , and an underside (or bottom surface)  111  that is opposite the top surface  110 . The left and right sides  112  and  114  extend between the front and back sides  108  and  109 . The back side  109  may have an arcuate shape (e.g., wherein the arc extends in a direction away from the front side  108 ) and the front side  108  may have a substantially planar shape. As such, in some instances, the housing  100  may generally be described as having a “D-shape.” While the robotic cleaner  101  is shown as having a D-shaped housing other configurations are possible. For example, the housing  100  may be round, oval, hexagonal, triangular, trapezoidal, and/or any other shape. 
     A user interface may extend along and/or define at least a portion of the top surface  110 . The user interface may include, for example, one or more indicators (e.g., one or more displays, one or more light emitting diodes, and/or any other indicator) configured to indicate a status of the robotic cleaner  101  (e.g., current operational mode, battery charge level, errors, and/or any other status), one or more inputs (e.g., buttons) configured to cause the robot to engage in one or more operations (e.g., autonomous cleaning, spot cleaning, docking, and/or any other operation), and/or any other feature of a user interface. 
       FIG. 2  shows a bottom view of a robotic cleaner  200 , which may be an example of the robotic cleaner  101  of  FIG. 1 . As shown, the robotic cleaner  200  includes a first agitator  202  and a second agitator  204  (e.g., a brush roll). In some instances, the first agitator  202  may have a different construction from the second agitator  204  (e.g., the first agitator  202  may comprise a microfiber and/or velvet material and the second agitator  204  may comprise one or more bristles and/or flaps). 
     The first agitator  202  may have bristles, fabric, or any other cleaning element, or any combination thereof. In one example, a microfiber or velvet fabric may extend around the first agitator  202 . The first agitator  202  may also be removable to allow first agitator  202  to be cleaned more easily, allow the user to change the size of the first agitator  202 , change the type of bristles on the first agitator  202 , and/or remove the first agitator  202  entirely depending on the intended application. 
     The second agitator  204  may have bristles, fabric, or any other cleaning element, or any combination thereof. In one example, the second agitator  204  may include one or more strips of bristles in combination with one or more strips (or flaps) of a rubber or elastomer material. The second agitator  204  may also be removable to allow second agitator  204  to be cleaned more easily, allow the user to change the size of the second agitator  204 , change the type of bristles on the second agitator  204 , and/or remove the second agitator  204  entirely depending on the intended application. 
     In operation, the first and second agitators  202  and  204  are configured to rotate about a corresponding agitator rotation axis  201  and  205 . The rotation axes  201  and  205  may extend substantially (e.g., within 1°, 2°, 3°, 4°, or 5° of) parallel to each other and/or extend substantially parallel to a surface to be cleaned. As such, the rotation axes  201  and  205  may, in some instances, be generally described as horizontal rotation axes. The first and second agitators  202  and  204  may be co-rotating or counter rotating. As shown, in some instances, one or more of the rotation axes  201  and/or  205  may extend substantially parallel to a front side  250  of a housing  252  of the robotic cleaner  200 . 
     The first and second agitators  202  and  204  can be configured to rotate about the rotation axes  201  and  205  such that debris on a surface to be cleaned is urged towards a dirty air (or debris) inlet defined with an agitator chamber (or suction conduit)  248 . The agitator chamber  248  may define a cavity within which the first and second agitators  202  and  204  are at least partially disposed. The cavity may have one or more open ends through which at least a portion of one or more of the agitators  202  and  204  may extend. The cavity may further be coupled to the dirty air inlet. At least one open end of the cavity may be defined in a bottom surface  251  of the housing  252  of the robotic cleaner  200 . 
     The dirty air inlet is fluidly coupled to a debris collector (or dust cup) and to a suction source (e.g., a suction motor) such that at least a portion of debris urged towards the dirty air inlet becomes entrained within air flowing into the dirty air inlet. At least a portion of the entrained debris may be deposited within the debris collector. The debris collector may be removably coupled to the housing  252  of the robotic cleaner  200  such that debris may be emptied therefrom. Rotation of the first and second agitators may be caused using one or more motors  249  (e.g., AC or DC motors). The one or more motors may be coupled to the first and second agitators  202  and  204  using one or more drive belts, one or more gears, and/or any other drive mechanism. 
     As shown, the first agitator  202  extends from the front side  250  of the housing  252  of the robotic cleaner  200 . As such, the first agitator  202  may define a forward most portion of the robotic cleaner  200 . In this example, the first rotation axis  201  may be positioned forward of the second rotation axis  205  such that, for example, the first rotation axis  201  extends between the front side  250  and the second rotation axis  205 . While the first agitator  202  is shown as being forward of the second agitator  204 , other configurations are possible. For example, the first agitator  202  may be positioned rearward of the second agitator  204 . In this example, the second agitator may define a forward most portion of the robotic cleaner  200 . Further, while the robotic cleaner  200  is shown as having a first and second agitator  202  and  204 , other configurations are possible. For example, the robotic cleaner  200  may include only one of the first or second agitators  202  and  204  and/or include additional agitators. 
     The robotic cleaner  200  also includes wheels  203  configured to be driven by one or more drive motors. The wheels  203  support the housing  252  at a position spaced apart from a surface to be cleaned and are configured to urge the robotic cleaner  200  across the surface to be cleaned in response to actuation of the one or more drive motors. The wheels  203  may be independently driven such that a direction of motion of the robotic cleaner  200  can be controlled through differential rotation of the wheels  203 . The wheels  203  may be mounted on respective suspension systems that bias the wheels in a direction away from the housing  252  (e.g., towards an extended position). For example, the suspension system may include a suspension arm pivotally coupled to the housing  252  such that the suspension arm is capable of transitioning between a retracted position and an extended position. The suspension system may further include a biasing mechanism (e.g., a spring) that urges the suspension arm towards the extended position. In some instances, one or more of a respective drive motor and/or a respective gearbox for transferring rotational movement from the drive motor to a respective wheel  203  may be coupled to the suspension arm. As such, the motor and/or gearbox may move with the suspension arm. 
     During operation, a weight of the robotic cleaner  200  causes the suspension systems of the respective wheels  203  to be in an intermediate position, the intermediate position being between the extended and retracted positions. A location of the intermediate position, relative to the extended and retracted positions, may vary based, at least in part, on the surface to be cleaned. The robotic cleaner  200  may also include wheel drop sensors (e.g., switches engaged by the suspension arm) to detect when the wheels are in the extended position. 
     The robotic cleaner  200  may include a controller configured to monitor sensor data (e.g., from one or more obstacle sensors, one or more floor type sensors, and/or any other sensors) and to control operation of the robotic cleaner  200  (e.g., based on the sensor data). For example, the controller may be communicatively coupled to one or more driving mechanisms (e.g., drive wheel motors, agitator motors, side brush motors, and/or any other driving mechanism) and one or more sensors. The controller can operate the drive motors, which drive the wheels, according to known techniques in the field of robotic cleaners. The controller may also cause the robotic cleaner  200  to perform various operations such as autonomous cleaning (including randomly moving and turning, wall following, and obstacle following), spot cleaning, and docking. The controller may also cause the robotic cleaner  200  to avoid obstacles and cliffs and to escape from various situations where the robotic cleaner  200  may become stuck. The controller may include any combination of hardware (e.g., one or more microprocessors) and software known for use in mobile robots. 
       FIG. 3  shows a perspective view of a robotic cleaner  300 , which may be an example of the robotic cleaner  101  of  FIG. 1 . As shown, the robotic cleaner  300  includes a housing  301  having a front side  310 , a back side  312  that is opposite the front side  310 , a left side  314 , a right side  316  that is opposite the left side  314 , an upper side (or top surface)  318 , and an underside (or bottom surface)  320  that is opposite the top surface  318 . One or more projections  302  may extend from the housing  301 . In some instances, the one or more projections  302  may define a distal most portion of the robotic cleaner  300 . In other instances, the one or more projections  302  may not define a distal most portion of the robotic cleaner  300 . 
     The one or more projections  302  may include and/or be configured to actuate one or more sensors  303 . For example, the one or more sensors  303  may include one or more cliff sensors configured to detect a non-traversable drop-off in the surface to be cleaned (or cliff). When the projections  302  are not the distal most portion of the robotic cleaner  300 , the projections  302  may include one or more reflectors configured to enable corresponding cliff sensors to transmit and receive cliff detection signals to and from the surface to be cleaned. For example, for an infrared (IR) cliff sensor, the one or more projections  302  may include a mirrored surface configured to direct IR emissions towards the surface to be cleaned. Additionally, or alternatively, the one or more projections  302  may be configured to transition between an extended and retracted position such that the one or more projections  302  are configured to transition towards a retracted position in response to contacting an obstacle. When in the retracted position, the one or more projections  302  may be configured to actuate at least one of the one or more sensors  303 , wherein actuation of the sensor  303  causes the sensor  303  to generate a signal indicating an obstacle has been encountered. In other words, when transitioning into the retracted position, the one or more projections  302  may cause an obstacle detection signal to be generated. In some instances, the robotic cleaner  300  may include a plurality of projections  302  that are spaced around the housing  301 . 
     The one or more projections  302  may extend from the housing  301  at a position between the top surface  318  and the bottom surface  320 . For example, the one or more projections  302  may be centrally disposed between the top and bottom surface  318  and  320 . By way of further example, the projections  302  may be disposed at a position closer to the top surface  318  than the bottom surface  320 . By way of still further example, the projections  302  may be disposed at a position closer to the bottom surface  320  than the top surface  318 . 
       FIGS. 4A and 5  show a schematic example of the robotic cleaner  300  having a plurality of projections  302 . As shown, the plurality of projections  302  include at least one forward projection  401  and at least one a side projection  403 . The projections  401  and  403  include cliff sensors configured to detect a non-traversable drop-off (e.g., stairs) in the surface to be cleaned. The forward projection  401  extends from the front side  310  of the housing  301  and each side projection  403  extends from a respective one of the left side  314  or the right side  316 . 
     The projections  401  and  403  are displaceable such that the projections  401  transition between extended and retracted positions (e.g., in response to engaging an obstacle). The projections  401  and  403  can be biased (e.g., using one or more springs) towards the extended position. As such, after disengaging an obstacle (e.g., a wall), the projections  401  and  403  transition towards the extended position. When transitioning between the extended and retracted positions, the projections  401  and  403  may move within a plane that extends substantially parallel to the top surface  318  of the housing  301  (e.g., a horizontal plane). 
     When in the extended position, the projections  401  and  403  may represent the distal most portions of the robotic cleaner  300 . When in the retracted position, the projections  401  and  403  may not be the distal most portion of the robotic cleaner  300 . For example, an agitator  404  of the robotic cleaner  300  may define the forward most portion of the robotic cleaner  300  (or the distal most portion in the forward direction) when the forward projection  401  is in the retracted position and, when the forward projection  401  is in the extended position, the forward projection  401  may extend beyond the agitator  404  such that the forward projection  401  defines the forward most portion of the robotic cleaner  300 . Such a configuration may allow the agitator  404  to engage (e.g., contact) an obstacle (e.g., a wall) extending from a surface to be cleaned. By way of further example, the agitator  404  of the robotic cleaner  300  may define the left and/or right most portions of the robotic cleaner  300  (or the distal most portion in the left and/or right direction) when the side projection  403  is in the retracted position and, when the side projection  403  is in the extended position, the side projection  403  may extend beyond the agitator  404  such that the side projection  403  defines the left and/or right most portions of the robotic cleaner  300 . 
     When the projections  401  and/or  403  transition into the retracted position, the projections  401  and/or  403  may actuate a respective sensor  303  (e.g., a switch such as a mechanical or optical switch) that generates a signal that is indicative of an obstacle being contacted. When the signal is received by a controller of the robotic cleaner  300 , the controller may cause the robotic cleaner  300  to engage in one or more behaviors (e.g., obstacle avoidance, obstacle cleaning, and/or any other behavior). 
       FIG. 4B  shows a magnified perspective view of a portion of the robotic cleaner  300 . As shown, the forward projection  401  may move linearly when transitioning between the extended and retracted positions and the side projection  403  may move pivotally when transitioning between the extended and retracted positions. However, other configurations are possible. For example, when transitioning between the extended and retracted positions, both projections  401  and  403  may move linearly, both projections  401  and  403  may move pivotally, or the forward projection  401  may move pivotally and the side projection  403  may move linearly. 
       FIG. 4C  shows a schematic example of the side projection  403 , wherein the side projection  403  is configured to pivot about a pivot point  410 . The pivot point  410  may be disposed within the housing  301  of the robotic cleaner  300  (e.g., the side projection  403  may be pivotally coupled to a chassis  411  of the robotic cleaner  300 ) such that, when transitioning into the retracted position, at least a portion of the side projection  403  moves into the housing  301 . A biasing mechanism (e.g., a spring) may urge the side projection  403  to pivot towards the extended position. When the side projection  403  encounters an obstacle, the side projection  403  is caused to pivot towards the retracted position. As shown, the side projection  403  may pivot in a substantially horizontal plane between the retracted and extended positions. 
     As also shown in  FIG. 4C , the side projection  403  may have a triangular shape, wherein the triangular shape may have rounded points. Such a configuration may encourage the transition of the side projection  403  between the extended position and the retracted position in response to engaging an obstacle. Other shapes are also within the scope of the present disclosure including, for example, oval, octagonal, or any other shape. 
       FIG. 6  shows a schematic cross-sectional view of a robotic cleaner  600 , which may be an example of the robotic cleaner  300  of  FIG. 3 . As shown, the robotic cleaner  600  may include a plurality of forward projections  602  and a plurality of side projections  604 , which may be examples of the forward and side projections  401  and  403 , respectively. One or more of the forward and/or side projections  602  and  604  are configured to transition between extended and retracted positions in response to engaging an obstacle. At least one of the forward and/or side projections  602  and  604  extend beyond an agitator  606  when in the extended position. The agitator  606  may extend beyond at least one of the forward and/or side projections  602  and  604  when an obstacle causes a respective projection  602  or  604  to transition to the retracted position. 
       FIGS. 7-10  show various perspective bottom views of the robotic cleaner  600  of  FIG. 6 . As shown, the robotic cleaner  600  includes one or more spiral brushes  608  configured to rotate about a spiral brush rotation axis  609 . The spiral brush rotation axis  609  is configured to extend substantially parallel to a bottom surface  610  of a housing  612  of the robotic cleaner  600  and/or to a surface to be cleaned. As shown, the one or more spiral brushes  608  extend along the spiral brush rotation axis  609  in a direction transverse (e.g., perpendicular) to a longitudinal length of the agitator  606 . In other words, the spiral brush rotation axis  609  may extend transverse (e.g., perpendicular) to an agitator rotation axis  611  about which the agitator  606  rotates. In some instances, the spiral brush rotation axis  609  may intersect the agitator  606 . The agitator rotation axis  611  may extend substantially parallel to the bottom surface  610  and/or to a surface to be cleaned. As such, in some instances, the agitator rotation axis  611  and the spiral brush rotation axis  609  may generally be described as being horizontal rotation axes. 
     The transverse positioning (relative to the agitator  606 ) of one or more spiral brushes  608  may allow for cleaning transverse to the agitator  606 . For example, such a configuration may allow the robotic cleaner  600  to clean alongside an obstacle or drop-off using the one or more spiral brushes  608 . Such a configuration may generally be described as creating a longer agitating surface along the edge of the obstacle or drop-off. 
     The one or more spiral brushes  608  may have a frustoconical shape about which one or more cleaning elements may extend. However, the one or more spiral brushes  608  may have any shape including cylindrical, octagonal, and/or any other shape. The cleaning elements may include any one or more of bristles, flaps, fabric (e.g., a velvet or microfiber), and/or any other cleaning element. For example, the one or more spiral brushes  608  may include at least one strip of bristles and at least one elastomeric flap extending along a body of the one or more spiral brushes  608  (e.g., in a helical pattern). Rotation of the one or more spiral brushes  608  causes the cleaning elements to engage the surface to be cleaned such that debris on the surface is urged towards a suction conduit. Rotation of the spiral brush  608  can be caused by one or more spiral brush motors. 
     The one or more spiral brushes  608  may be received within a spiral brush cavity  614 , wherein at least a portion of the one or more spiral brushes  608  extend from an open end of the spiral brush cavity  614  in a direction of a surface to be cleaned. The spiral brush cavity  614  may include one or more couplings for rotatably coupling the one or more spiral brushes  608  to the housing  612 . At least one of the one or more couplings may couple the one or more spiral brushes  608  to a respective spiral brush motor. In some instances, the one or more spiral brushes  608  may be removably coupled to the housing  612 . Such a configuration may allow the one or more spiral brushes  608  to be more easily cleaned and/or replaced. Replacement of the one or more spiral brushes  608  may allow a user to select a spiral brush based on a desired cleaning behavior (e.g., a spiral brush with different cleaning elements and/or different size/shape). In some instances, the one or more spiral brushes  608  may be removed entirely and the robotic cleaner  600  may be configured to operate without the one or more spiral brushes. 
       FIGS. 11-16  show schematic examples of a robotic cleaner  1100 , which may be an example of the robotic cleaner  101  of  FIG. 1 . As shown, the robotic cleaner  1100  includes a housing  1102  and an agitator  902  configured to be rotated relative to the housing  1102 . The agitator  902  can be configured to detect engagement with an obstacle and/or an existence of a non-traversable drop-off (or cliff). For example, the agitator  902  can be configured to move along one or more of a drop axis  1101  and/or a forward bump axis  1103 , wherein movement along the drop axis  1101  and/or the forward bump axis  1103  may be configured to actuate a sensor (e.g., an optical or mechanical switch), generating a detection signal, after a predetermined amount of movement. As such, movement of the agitator  902  along the forward bump axis  1103  may be indicative of a presence of an obstacle extending from a surface to be cleaned  1120 , wherein the obstacle impedes forward movement of the robotic cleaner  1100 , and movement of the agitator  902  along the drop axis  1101  may be indicative of a presence of a non-traversable drop-off (or cliff). Therefore, in some instances, the agitator  902  may generally be described as providing obstacle and/or drop-off sensing. When the agitator  902  moves along both the drop axis  1101  and the forward bump axis  1103 , the agitator  902  may be generally be described as being configured to float. 
     The forward bump axis  1103  extends substantially parallel to a direction of forward movement of the robotic cleaner  1100  and the drop axis  1101  extends substantially perpendicular to a surface to be cleaned  1120 . In other words, the forward bump axis  1103  extends transverse (e.g., perpendicular) to a front side  1104  and a back side  1106  of the housing  1102  of the robotic cleaner  1100  and the drop axis  1101  extends transverse (e.g., perpendicular) to an upper side  1108  and an underside  1110  of the housing  1102 . As such, when the agitator  902  is capable of moving along both the forward bump axis  1103  and the drop axis  1101 , the forward bump axis  1103  may generally be described as extending transverse (e.g., perpendicular) to the drop axis  1101 . In some instances, the forward bump axis  1103  may generally be described as being a horizontal axis and the drop axis  1101  may generally be described as being a vertical axis. 
     In some instances, movement of the agitator  902  along one or more of the drop axis  1101  and/or the forward bump axis  1103  may be caused by movement of a sole plate. For example, the agitator  902  may be rotatably coupled to the sole plate such that a movement of the sole plate is transferred to the agitator  902 . In this example, when the robotic cleaner  1100  encounters a non-traversable drop-off, the sole plate may move along the drop axis  1101  along with the agitator  902 . Alternatively, the sole plate may move independently from the agitator  902  (e.g., the agitator may be fixed relative to the drop axis  1101  and the forward bump axis  1103 ) such that movement of the sole plate is indicative of the presence of an obstacle and/or a non-traversable drop-off. Movement of the sole plate may actuate a sensor (e.g., switch) configured to generate a signal indicative of a non-traversable drop-off and/or obstacle being encountered. 
     When the agitator  902  is configured to provide obstacle and/or non-traversable drop-off sensing, additional obstacle and/or non-traversable drop-off sensors may be omitted. For example, one or more forward and/or side projections  901  and/or  903  having cliff sensors may be omitted. Alternatively, for example, the robotic cleaner may include one or more forward and/or side projections  901  and/or  903  having cliff sensors to increase a confidence level in detecting a non-traversable drop-off. Such configurations may allow the agitator  902  to clean the edge of the drop-off before engaging in a cliff avoidance behavior (e.g., turning and/or reversing). By way of further example, when the agitator  902  provides forward obstacle detection, a bumper may be omitted and the agitator  902  may define the forward most portion of the robotic cleaner  1100 . Such a configuration may allow the robotic cleaner  1100  to clean at least a portion of a vertically extending surface of the obstacle (e.g., a leg of a piece of furniture such as a chair or a wall) using the agitator  902  before engaging in an obstacle avoidance behavior (e.g., turning and/or reversing). 
     An example of a robotic cleaner, consistent with the present disclosure, may include a housing, an agitator, and one or more projections. The housing may have a front side, a back side opposite the front side, a left side, and a right side opposite the left side. The right and left sides extend between the front and back sides. The agitator may be configured to rotate about an agitator rotation axis, the agitator rotation axis extending substantially parallel to the front side. The one or more projections may extend from the housing. The one or more projections may include one or more cliff sensors. 
     In some instances, the one or more projections may include at least one forward projection and at least one side projection, the at least one forward projection extending from the front side of the housing and the at least one side projection extending from a respective one of the left side or the right side of the housing. In some instances, the agitator may extend from the front side of the housing. In some instances, the forward projection may extend beyond the agitator. In some instances, the one or more projections may be configured to transition between an extended position and a retracted position in response to engaging an obstacle. In some instances, when at least one of the one or more projections transition into the retracted position, an obstacle detection signal may be caused to be generated. In some instances, the agitator may be configured to move along at least one of a drop axis or a forward bump axis. In some instances, the agitator may be configured to move along the drop axis and movement along the drop axis may be indicative of a presence of a cliff. In some instances, the agitator may extend from the front side of the housing and may be configured to move along the forward bump axis, movement along the forward bump axis may be indicative of a presence of an obstacle. In some instances, the robotic cleaner may further include a spiral brush configured to rotate about a spiral brush rotation axis, the spiral brush rotation axis extending substantially parallel to a surface to be cleaned and transverse to the agitator rotation axis. 
     Another example of a robotic cleaner, consistent with the present disclosure, may include a housing having a front side and a back side opposite the front side and an agitator extending from the front side of the housing. The agitator may be configured to rotate about an agitator rotation axis. The agitator rotation axis may extend substantially parallel to the front side. The agitator may be further configured to move along a drop axis and a forward bump axis. Movement along the drop axis may be indicative of a presence of a cliff and movement along the forward bump axis may be indicative of a presence of an obstacle. 
     In some instances, the robotic cleaner may further include one or more projections extending from the housing and the one or more projections may include one or more cliff sensors. In some instances, the one or more projections may be configured to transition between an extended position and a retracted position in response to engaging an obstacle. In some instances, when at least one of the one or more projections transition into the retracted position, an obstacle detection signal may be caused to be generated. In some instances, the robotic cleaner may further include a spiral brush configured to rotate about a spiral brush rotation axis, the spiral brush rotation axis extending substantially parallel to a surface to be cleaned and transverse to the agitator rotation axis. 
     Another example of a robotic cleaner, consistent with the present disclosure, may include a housing, an agitator, and a spiral brush. The housing may have a front side and a back side opposite the front side. The agitator may be configured to rotate about an agitator rotation axis. The agitator rotation axis may extend substantially parallel to the front side and substantially parallel to a surface to be cleaned. The spiral brush may be configured to rotate about a spiral brush rotation axis. The spiral brush rotation axis may extend substantially parallel to the surface to be cleaned and transverse to the agitator rotation axis. 
     In some instances, the robotic cleaner may further include one or more projections extending from the housing and the one or more projections may include one or more cliff sensors. In some instances, the one or more projections may be configured to transition between an extended position and a retracted position in response to engaging an obstacle. In some instances, when at least one of the one or more projections transition into the retracted position, an obstacle detection signal may be caused to be generated. In some instances, the agitator may be further configured to move along a drop axis and a forward bump axis, movement along the drop axis may be indicative of a presence of a cliff and movement along the forward bump axis may be indicative of a presence of an obstacle. 
     While the principles of the invention have been described herein, it is to be understood by those skilled in the art that this description is made only by way of example and not as a limitation as to the scope of the invention. Other embodiments are contemplated within the scope of the present invention in addition to the exemplary embodiments shown and described herein. Modifications and substitutions by one of ordinary skill in the art are considered to be within the scope of the present invention, which is not to be limited except by the following claims.