Patent Publication Number: US-11039722-B2

Title: Assisted drive for surface cleaning devices

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/661,504 filed on Apr. 23, 2018, which is fully incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to surface cleaning devices such as vacuums, and more particularly, to a drive-assisted surface cleaning device capable of translating user input into a command signal to drive the nozzle in a desired direction to reduce the amount of force a user exerts while performing cleaning operations. 
     BACKGROUND INFORMATION 
     Powered devices, such as vacuum cleaners, have multiple components that each receive electrical power from one or more power sources (e.g., one or more batteries or electrical mains). For example, a vacuum cleaner may include a suction motor to generate a vacuum within a cleaning head/nozzle. The generated vacuum collects debris from a surface to be cleaned and deposits the debris, for example, in a debris collector or dust cup. The vacuum may also include a motor to rotate a brushroll within the cleaning head. The rotation of the brushroll agitates debris that has adhered to the surface to be cleaned such that the generated vacuum is capable of removing the debris from the surface. In addition to electrical components for cleaning, the vacuum cleaner may include one or more light sources to illuminate an area to be cleaned. 
     Vacuum cleaners such as so-called upright vacuums include a handle portion for operating the vacuum during cleaning operations. The amount of force required to push, pull and steer the vacuum varies widely based on, for example, the type of vacuum, the surface to be cleaned and any cleaning elements such as brushes which engage the surface to be cleaned. Users may therefore experience muscle fatigue, e.g., in wrists and arms, after continuous application of such manual force and while supporting a portion of the vacuums weight via the handle portion. 
    
    
     
       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. 1A  shows a schematic diagram of an assisted drive system for use in surface cleaning device, in accordance with embodiments of the present disclosure. 
         FIG. 1B  shows an example vacuum cleaner device implementing the assisted drive system of  FIG. 1A , in accordance with an embodiment. 
         FIG. 1C  shows another perspective view of the vacuum cleaner device of  FIG. 1B , in accordance with an embodiment. 
         FIG. 2  shows an example swivel base and handle-coupling portion of a surface cleaning device that implements the assisted drive system of  FIG. 1 , in accordance with an embodiment. 
         FIG. 3A  shows the example swivel base and handle coupling portion of  FIG. 2  implemented in a partially-exploded upright vacuum device, in accordance with an embodiment of the present disclosure. 
         FIG. 3B  shows a cross-sectional view of the partially-exploded upright vacuum device of  FIG. 3A , in accordance with an embodiment of the present disclosure. 
         FIG. 4  is a schematic representation of an example load cell consistent with embodiments of the present disclosure. 
         FIG. 5A  shows a vacuum device with a detachable upright portion consistent with an embodiment of the present disclosure. 
         FIG. 5B  shows another perspective view of the vacuum device of  FIG. 5A  consistent with an embodiment of the present disclosure. 
         FIG. 6A  shows a top-down view of an example surface cleaning device implementing a brush-driven drive assist arrangement consistent with embodiments of the present disclosure. 
         FIG. 6B  shows a side view of the example surface cleaning device of  FIG. 6A  in accordance with an embodiment. 
         FIG. 7  shows a block diagram that schematically illustrates a vacuum device implementing a brush-driven drive assist arrangement consistent with embodiments of the present disclosure. 
         FIG. 8  shows a block diagram that schematically illustrates a robotic vacuum device implementing a brush-driven drive assist arrangement consistent with embodiments of the present disclosure. 
         FIG. 9A  shows an example brushroll arrangement consistent with aspects of the present disclosure. 
         FIG. 9B  shows another example brushroll arrangement consistent with aspects of the present disclosure. 
         FIG. 9C  shows another example brushroll arrangement consistent with aspects of the present disclosure. 
         FIG. 9D  shows yet another example brushroll arrangement consistent with aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In general, the present disclosure is directed to a force-sensing arrangement for use in surface cleaning devices, such as a vacuum device, that allows a user-supplied force to be translated into a command signal to cause the surface cleaning device to accelerate forward, reverse and/or to veer in a desired direction. In an embodiment, the surface cleaning device includes a nozzle, wheels (and/or treads), motor(s) to drive the wheels, and an upright handle portion. The surface cleaning device includes a force-sensing arrangement with load cells coupled at a position where user force is transferred from the upright portion to the nozzle. The force-sensing arrangement detects the user supplying a relatively small amount of force, e.g., relative to the force required to push/pulls/steer a conventional upright vacuum, and translates the same into measurement signals. A controller coupled to the load cells utilizes the measurement signals to determine or “infer” a desired direction of travel. The controller then generates a control signal (also referred to herein as a command signal) to drive the motor and move the surface cleaning device in a desired direction or otherwise adjust cleaning operations. Thus, in a general sense, the force-sensing arrangement allows the surface cleaning device to “sense” the movements of the user based on the user-supplied force and convert the same into control commands. 
     A surface cleaning device having a force-sensing arrangement consistent with the present disclosure allows for a user to supply a relatively small amount of force to control the surface cleaning device and advantageously minimizes or otherwise reduces muscle fatigue during cleaning operations. In addition, the surface cleaning device can include a force-sensing arrangement consistent with the present disclosure without necessarily changing the aesthetics and function of the surface cleaning device. For example, a vacuum configured with the force-sensing arrangement may appear to have no observable indication that the force-sensing arrangement is present. Accordingly, such a vacuum may be appear to be “standard” and have a handle portion that does not include a visible user input device, such as a sliding portion coupled to the handle or bendable neck, which other surface cleaning device approaches utilize to detect user input. Instead, the vacuum can include the force sensor arrangement proximate the nozzle, and in some cases, integrated into the nozzle housing or otherwise obscured by a cover portion thereof, to obscure the force sensor arrangement from view. Thus, the vacuum may be utilized in an intuitive, conventional way by a user without the visual or mechanical nuisances other surface cleaning devices include to provide drive-assist features. 
     In addition, a surface cleaning device having a force-sensing arrangement consistent with the present disclosure can allow for selection of operational modes, e.g., sport mode, regular mode, custom mode, and so on. This mode selection may be engaged by a user to change the amount of assistance when detecting and converting the user-supplied force, e.g., the vacuum may accelerate and/or steer more vigorously/rapidly in response to a user force when in sport mode, or less when in a regular mode. The mode may be selectable via an app, or a control of the vacuum, or both. Alternatively, or in addition, the force sensor arrangement can change the assistance amount in proportion to the magnitude of force applied by a user. 
     In another example embodiment, a vacuum consistent with the present disclosure utilizes a brush-driven drive assist arrangement, also referred to herein as a brushroll drive system, that is configured to accelerate/move the vacuum forward, reverse and to veer in a desired direction based on brushroll communication with the surface to be cleaned. The brush roll drive system utilizes communication, e.g., friction, between a given surface and the brushrolls to “draw” the vacuum in the desired direction. The brush-driven drive assist arrangement can also detect a surface type and extend or retract the brushrolls to increase or decrease such communication with a surface based on the detected surface type. In this embodiment, the vacuum may include at least a first and a second brushroll, with each brushroll being disposed substantially coaxial with each other. This brushroll arrangement may be utilized to generate/create a turning moment, as discussed in greater detail below, to allow user to “veer” to the right or left during cleaning operations. To accomplish the turning moment, each brushroll may be independently driven (e.g., asymmetrically) to cause the vacuum to turn/veer left/right. The signal to move forward, back and veer may be generated based on the force-sensing arrangement disclosed herein. The brushroll drive system disclosed herein allows a surface cleaning device to move without the use of wheels, treads, speed encoders, gears, and so on, which may advantageously reduce manufacturing complexity and costs. 
     Turning to the Figures,  FIG. 1A  shows an example assisted drive system  100  for use in a surface cleaning device, consistent with embodiments of the present disclosure. The example assisted drive system  100  can be disposed in a housing  102 , such as the nozzle of a vacuum or other suitable location. The example assisted drive system  100  includes a controller  104 , a motor control circuit  106 , a force-sensing arrangement  108 , first and second motors  306 - 1 ,  306 - 2 , and first and second wheels  308 - 1 ,  308 - 2 . Note, the force-sensing arrangement  108  may also be referred to herein as a force sensor arrangement  108 . The embodiment of  FIG. 1A  is in a highly simplified form for ease of description and clarity. For instance, a surface cleaning device consistent with the present disclosure can an include one or more of a suction motor, floor-type detectors, and other components that may be used in combination with the example assisted drive system  100 . 
     The controller  104  comprises at least one processing device/circuit such as, for example, a digital signal processor (DSP), a field-programmable gate array (FPGA), Reduced Instruction Set Computer (RISC) processor, x86 instruction set processor, microcontroller, an application-specific integrated circuit (ASIC). The controller  104  may comprise a single chip, or multiple separate chips/circuitry. The controller  104  may implement various methods and techniques disclosed herein using software (e.g., C or C++ executing on the controller/processor  104 ), hardware (e.g., circuitry, hardcoded gate level logic or purpose-built silicon) or firmware (e.g., embedded routines executing on a microcontroller), or any combination thereof. The controller  104  can receive signals, e.g., force measurement signals, from the force-sensing arrangement, as discussed in greater detail below, and can convert the same into control signals to control operation of a surface cleaning device. 
     The power source  110  comprises any suitable power source capable of generating power at a suitable voltage for use by the controller  104  and force-sensing arrangement  108 , for instance. Thus, the power source  110  can include power converters (e.g., DC-DC converters), regulators and other circuitry capable of converting power, e.g., from AC mains, into stepped-down DC signal for use by the components of the surface cleaning device. Alternatively, or in addition, the power source  110  may include one or more battery cells for powering the components of the surface cleaning device. 
     The motor control circuit  106  comprises any suitable chip/circuitry that can send signals to first and second motors  306 - 1 ,  306 - 2  to independently cause each to drive the first and second wheels  308 - 1 ,  308 - 2 , respectively. The motor control circuit  106  may also be configured to command/control other motors, such as those that drive brushrolls/agitators and other components of a surface cleaning device. 
     The force-sensing arrangement  108  includes at least one force sensor capable of measuring tension or compression forces and outputting a proportional electrical signal. In an embodiment, the force-sensing arrangement  108  includes at least one load cell, such as the load cell shown in  FIG. 4 . However, other types of force/tensioning sensors are within the scope of this disclosure. As is discussed in greater detail below, the force-sensing arrangement  108  can include load cells disposed proximate a location where an upright handle portion (also referred to as a wand in some applications) connects with, and transfers user-supplied forces, to a nozzle/body of the surface cleaning device. 
     Thus, a surface cleaning device having a force-sensing arrangement consistent with the present disclosure advantageously provides a relatively transparent sensing approach whereby normal usage, and in particular, normal forces from a user to operate a surface cleaning device can be detected and used to control assistive operations without a user having to necessarily interact with a specialized input device. Simply stated, the force sensor arrangement disclosed herein significantly simplifies user access and full utilization of sophisticated features, e.g., assistive driving, without specialized training or conscious effort. 
       FIGS. 1B and 1C  collectively show the assisted drive system  100  implemented within an example vacuum device  120  in accordance with an embodiment. As shown, the vacuum device  120  includes a base portion  122 , wheels  123 , and an upright portion  124 . The upright portion  124  includes a handle  125  which may be shaped to be comfortably gripped by a user  126 . The base  122  may include a nozzle for receiving dirt and debris and a dust cup for storage of the received dirt and debris. The particular configuration shown in  FIGS. 1B and 1C  is not intended to be limiting and other implementations are within the scope of this disclosure. 
     The base  122  includes the force-sensing arrangement  108  and is configured to sense movement of the upright portion  124  and convert the same into a force measurement signal. The base  122  or other portion of the vacuum device  120  can include the controller  104  to receive the force measurement signal. In response, the controller  104  provides a signal to drive the wheels  123  in a direction consistent with the force applied by the user  126  and/or to provide a signal to drive brush rolls to cause the vacuum device  120  to move in a direction consistent with the user-supplied force. For instance, the input signal may also be utilized to transition between multiple brushroll speeds and directions to create a torque vector on the base/nozzle, as is discussed in greater detail below. This brush-driven drive assist approach allows the vacuum device  120  to veer/turn based on a relatively small amount of force supplied by a user, e.g., by a user “twisting” their wrist while gripping the handle  125 . 
     In any event, the controller  104  can “infer” a desired movement by a user and drive the vacuum device  120  in a motorized fashion in a plurality of directions including forward (away from the user  126 ), reverse (towards the user  126 ), left, and right. Alternatively, or in addition to movement commands, the controller  104  can perform at least one operational change including modification of the nozzle&#39;s interaction with a surface to be cleaned (e.g., change height to accommodate different floor types), adjust cleaning element floor engagement, adjust brush roll speed and/or direction, adjust suction power, articulate bristle strips, and/or adjust soleplate geometry. 
     In an embodiment, the user input detected by the controller  104  can be used to detect a desired action to perform. For instance, the user input may indicate a particular scrubbing action is desired based on a user performing a wrist-flick or other predefined gesture. In one specific example, a user may provide a relatively quick back and forth motion, and in response thereto, the controller  104  may generate a signal that causes one or more of the aforementioned operational changes. The vacuum device  120  may be configured to recognize a plurality of so called real-world gestures, e.g., a scrubbing motion, and may be trained to adjust cleaning operation accordingly. For example, the user input may be identified by the controller  104  as a predefined gesture, and in response to identifying a predefined gesture, the vacuum device  120  can raise/lower a cleaning element to perform ‘scrubbing’ on a particular region of interest to be cleaned. The cleaning element may comprise an attachment or tool, for example, and the tool may be automatically deployed in response to detection of the predefined gesture. 
     In one specific example embodiment, the ‘style’ a user employs while operating the vacuum device  120  may be learned over time and used to train the vacuum device  120 . For example, the vacuum  120  may ‘learn’ that a user prefers a particular mode, e.g., sport, normal, etc., and may vary the responsiveness of the assistive drive and/or operational changes based on learned preferences. 
     Turning to  FIGS. 2-3B , with additional reference to  FIGS. 1A-1C , a force-sensing arrangement  200  is shown coupled to a swivel base and handle-coupling portion of a surface cleaning device, in accordance with an embodiment of the present disclosure. The force-sensing arrangement  200  includes a handle/upright coupling portion  231 , a swivel base portion  232 , and first and second load cells  233 - 1  and  233 - 2 . In an embodiment, the first and second load cells  233 - 1  and  233 - 2  may be electrically coupled to the controller  104  ( FIG. 1 ) within the housing section  234 , although the controller  104  may be disposed at a different location depending on a desired configuration. 
     The handle coupling portion  231  defines a cavity  240  that extends along a longitudinal axis  242  of the handle coupling portion  231 . A first end  244 - 1  of the cavity is configured to at least partially receive and couple to a handle, e.g., handle  125  ( FIG. 1B ). The second end of the cavity  244 - 2  is at least partially defined by the swivel base  232 . 
     The swivel base  232  extends from the handle coupling portion  231  and at least partially defines the cavity  240 . The swivel base  232  includes a body that defines at least one projection (or axle), e.g., projection  238 , that extends substantially transverse relative to the longitudinal axis  242 , and preferably, at least two projections that extend opposite from each other. The projections of the swivel base  232  may be substantially coaxial and thus may collectively form a single axle. The projections are configured to extend into a cavity of the load cells  233 - 1 ,  233 - 2 , for force sensing purposes as is discussed in further detail below. 
     As shown, the first and second load cells  233 - 1 ,  233 - 2  are securely attached to the nozzle  304  (See  FIG. 3A ) and allow for the swivel base portion  232  to move in a plurality of directions based on user input. The first and second load cells  233 - 1  and  233 - 2  securely attached to the nozzle  304  proximate the surface to be cleaned  235  ensures that the measurements get taken parallel or substantially parallel with the same, which advantageously reduces the influence of mass on those measurements. This position particularly well suited for such measurements as the sensing axis  445  remains naturally oriented with the floor plane. Moreover, the point where load is transferred from the user  126  into the nozzle  304  is the interface with the swivel base portion  232 . The two load cells  233 - 1 ,  233 - 2  can be placed at this interface/fulcrum such as shown. Parallel to the floor and aligned on axis  236  ( FIG. 2A ) via project  238 , results in each load cell  233 - 1 ,  233 - 2  being particularly sensitive to forces applied in a forward/backward direction D 1 /D 2 . 
     This arrangement of sensors  233 - 1  and  233 - 2  may be referred to as a symmetric sensor arrangement. In an embodiment, the output of the first and second load cells  233 - 1  and  233 - 2  is provided to the controller  104  in the form of force measurement values. The controller  104  may then receive the output and take an average of each load cell&#39;s output as force is supplied by the user  126  to establish if forward/back movement has been detected. Likewise, the difference between the output values of each load cell may be used to estimate a value representing turning torque to cause a veering movement to the right or left, as is discussed in further detail below. 
     Thus, and in accordance with an embodiment, force and/or torque supplied by a user on the upright portion  124  ( FIG. 1B ), and more specifically, the handle  125 , may be measured by the force-sensing arrangement  200 . In operation, the force-sensing arrangement  200  therefore allows the user  126  to direct the vacuum device  120  across the floor/surface to be cleaned based at least in part on forward/back motion and/or turning motions. 
       FIG. 4  shows an example schematic view of a load cell  433  suitable for use in the force-sensing arrangement  200  of  FIG. 2 . As shown, the load cell  433  includes a load sensor  402  coupled to sensor plate  404 , a frame (or housing)  410 , a sliding engagement member  420 , an opening  447 , and a spring device  443 . The opening  447  is configured to receive at least a portion of the swivel axle  238 . 
     In an embodiment, the load sensor  402  comprises a strain gauge, although other force/torque measuring devices are within the scope of this disclosure. The spring device  443  supplies a biasing force towards the swivel axle  238  which maintains the sliding engagement member  420  against the swivel axle  238 . Therefore, the sliding engagement member  420  may be spring-loaded based on the spring device  443 . The frame  410  allows for horizontal movement of the swivel axle  238 , e.g., along the force sensing axis  445 , but otherwise prevents vertical movement of the swivel axle  238 . As shown, the force provided by the spring device  443  maintains the load sensor  433  in a neutral state (e.g., by applying a substantially constant amount of force) whereby the force sensor  402  outputs a measurement in a predefined range, and preferably, substantially a center of the predefined range, so that force may be sensed in both directions along the sensing axis  445 . 
     Therefore, two independent force measurements may be received by the controller  104  to determine a desired/target direction of movement. In particular, the first and second load cells  233 - 1 ,  233 - 2  may be utilized to measure force/torque based on the movement of the swivel axles. As is discussed above, each of the first and second load cells  233 - 1 ,  233 - 2  can include a spring-biased (or spring-loaded) sliding engagement member  420  that applies a predefined amount of force in a neutral state. Movement of the swivel axles thus results in first and second measurement signals from the first and second cells  233 - 1 ,  233 - 2 , respectively, to deviate/shift from the predefined amount of force provided in the neutral state, and thus, allows the controller  104  to identify a desired/target direction. 
     In more detail, the measured force/torque signal output by the first and second load cells  233 - 1 ,  233 - 2  may then be received by the controller  104  and used to infer or otherwise identify a desired direction of travel. For example, consider a scenario whereby the user  126  applies a force to cause the vacuum device  120  to travel straight forward along direction D 1  (See  FIG. 1C ). In this scenario, the first and second measurement signals from the first and second load cells  233 - 1 ,  233 - 2 , respectively, can indicate a substantially equal amount of force being applied in the same direction, i.e., direction D 1 . Also in this scenario, the first and second signals from the first and second load cells  233 - 1 ,  233 - 2  indicate a measured force value that is less than the steady-state or neutral force value. This reduction of measured force occurs in response to the upright portion  124  pushing the swivel axles away from the force sensor  402 . 
     The opposite holds true in scenarios where a user applies a force to cause the vacuum device  120  to travel straight backward along direction D 2 . In this scenario, the swivel axles travel towards the sensor  402  of each of the first and second load cells  233 - 1 ,  233 - 2 , which then causes the same to output first and second signals, respectively, that indicate a measured force value that is greater than the predefined neutral force value. 
     In any such cases, the controller  104  can infer/identify the target direction is straight forward along D 1  or straight backward along D 2 , and in response to identifying the target direction can generate a movement command. The movement command may then be provided to the motor control circuit  106 , for example, to cause the same to drive the wheels, and by extension the vacuum device  120 , forward or backward as the case may be. 
     Now consider a scenario wherein the user  126  applies a torque force to the upright portion  124  to cause the vacuum device  120  to veer or otherwise change direction. In this scenario, the first and second load cells  233 - 1 ,  233 - 2  output measurement values that are substantially equal in magnitude relative to the predefined neutral force. However, the direction of the torque results in one of the load cells outputting a force value greater than the predefined neutral force value and the other load cell outputting a force value less than the predefined neutral force value. The controller  104  can therefore identify if veering in a different direction is desired based on the output signals of the first and second load cells  233 - 1 ,  233 - 2  indicating opposite directionality of measured forces, e.g., based on the first and second load cells  233 - 1 ,  233 - 2  outputting respective measurement values that are greater than and less than the predetermined neutral force, respectively, or vice-versa. 
     In addition, the particular target direction to veer/turn towards can be determined based on which load cell outputs a measured force greater than the predetermined neutral force value. For instance, veering toward direction D 3  (See  FIG. 1C ) can result in the second load cell  233 - 2  outputting a measured force value that is greater than the predetermined neutral state value. On the other hand, in this example the first load cell  233 - 1  outputs a measured force value that is less than the predetermined neutral state value. The controller  104  can therefore determine the user  126  desires to veer or turn towards direction D 3 , e.g., to the left, based on the second load cell  233 - 2  measuring force greater than the predetermined neutral state force, and the second load cell  233 - 2  measuring a force less than the predetermined neutral state value. In instances where the user desires to reorient the vacuum device  120  in a different direction, the controller  104  can receive the torque measurements as discussed above and assist the user by causing the motor control circuit  106  to drive the associated wheels such that the nozzle of the vacuum  120  pivots in place. This pivoting may be accomplished by the controller  104  sending a command to the motor control circuit  106  to drive one the wheel to the exclusion of the other, thus resulting in a pivoting movement. 
     In addition, the controller  104  can utilize the magnitude of the measured force values from the first and second load cells  233 - 1 ,  233 - 2 , to also command the motor control circuit  106  to move/accelerate the vacuum device  120  forward, or backward, while also veering/turning in a target direction. For example, in a prior example provided above the user  126  veered towards direction D 3 , which is to say to the left. At the same instance in time the user may also be supplying a force to push the vacuum device  120  forward. The magnitude of the measured force, e.g., relative to the predetermined neutral force, can therefore be utilized by the controller  104  to also vary the speed of movement of the vacuum device while performing the veering movement. 
       FIGS. 5A and 5B  show another example embodiment of a vacuum device  120 B consistent with the present disclosure. The vacuum device  120 B may be configured substantially similar to that of the vacuum device  120 A of  FIGS. 1B and 1C , the description of which is equally applicable to the vacuum device  120 B and will not be repeated for brevity. However, the vacuum device  120 B includes a detachable upright portion  504 . The user  126  may therefore detach/decouple the upright portion  504  from the base  502 . The upright portion  504  may then be optionally used to remotely control the base portion  502  by the user  126 . The base portion  502  can then operate as a robotic vacuum device to perform autonomous, semi-autonomous, and/or manual cleaning based on remote input. The remote input may be provided by movement of the upright portion  504 , e.g. the user simulating cleaning motions or performing other predefined gestures. In an embodiment, the upright portion  504  may be implemented as the hand-held surface cleaning device disclosed and described in the co-pending application entitled “HAND-HELD VACUUM WITH ROBOTIC VACUUM CONTROL ARRANGEMENT” which is incorporated by reference herein in its entirety. In this embodiment, the detachable portion may be simply the handle  505 , and this disclosure is not intended to be limiting in this regard. 
     Although the aspects and embodiments discussed above include a vacuum device with wheels and associated circuitry/motors for driving the same, this disclosure is not limited in this regard. For example,  FIGS. 6A and 6B  show an example vacuum device  600  with a brushroll driving scheme that may be used alone, i.e., without the necessity of wheels/tracks, to drive/propel the vacuum device. Utilizing the brush rolls exclusively in this manner may reduce the number of components, e.g., eliminate the need for gears, wheels/tracks, gear boxes, speed encoders, suspension arrangements, etc., which may advantageously reduce manufacturing complexity and cost. 
     The vacuum device  600  may be implemented as an upright vacuum device, e.g., vacuum device  120 A ( FIGS. 1B-1C ) and/or vacuum device  120 B ( FIGS. 5A-5B ). The vacuum device  600  can also be implemented as a robotic vacuum that includes circuitry and software/firmware to support autonomous (or semi-autonomous) cleaning operations/modes. Preferably, the robotic vacuum  600  can operate in a plurality of modes including in an upright mode with drive-assisted functions, as discussed above with regard to  FIGS. 1A-3B , a remote-controlled mode as discussed above with regard to  FIGS. 5A and 5B , and/or a fully or partially autonomous robot vacuum, e.g., with autonomous navigation circuitry. 
     As shown, the vacuum device  600  includes a housing  602  and a plurality of brushrolls, e.g., first and second brushrolls  604 - 1 ,  604 - 2 . The first and second brushrolls  604 - 1 ,  604 - 2  are disposed substantially coaxial with each other. The vacuum device  600  further includes a vacuum motor  610 , cyclonic member  612 , batteries  618  and a dust cup  614 . The vacuum device  600  may further include the controller  104  (See  FIG. 1A ) that can provide a signal to each of the first and second brushrolls  604 - 1 ,  604 - 2  by way of the motor control circuit  106  to independently control each. The controller  104  may therefore cause the vacuum device  600  to accelerate forwards, backwards and to veer via differential engagement of the first and second brushrolls  604 - 1 ,  604 - 2  on a surface to be cleaned to provide friction/traction and turning movements. This differential arrangement may also be referred to as a brush-driven drive assist arrangement. The housing  602  may further be weighted to increase communication and friction with a surface to be cleaned. 
     In an embodiment, the first and second brushroll  604 - 1  and  604 - 2  may be spaced apart to provide a gap  608  there between. The gap  608  may be used to advantageously prevent hair/debris from tangling up with the brushrolls. The gap  608  may be aligned with the vacuum port (or dirty air inlet) and the dust cup such that hair/debris is released continuously off the two brushrolls  604 - 1 ,  604 - 2  into the airstream to eliminate the necessity of removing the brushrolls to clean the hair off. 
     The first and second brushrolls  604 - 1 ,  604 - 2  may be fixed or removable from the base  602 . The first and second brushrolls  604 - 1 ,  604 - 2  may be driven independently from each other, as opposed to other approaches that utilize a single brushroll or a center driving scheme. The profile and features on each brushroll may be configured such that hair/debris is managed and directed towards the gap in the center. The brushrolls may utilize rubber blades, shielded bristles, and/or the shape/contours of the brush rolls themselves (e.g., a conical shape or other geometric shape). Some additional example embodiments for brushroll configurations to direct hair off of the rolls are shown in  FIGS. 9A-9C . 
     Turning to  FIG. 7 , an embodiment of a vacuum device  700  having a brush-driven drive assist arrangement consistent with the present disclosure is shown. As shown, the vacuum device  700  is shown in a highly simplified form for purposes of clarity and not for limitation. The vacuum device  700  includes a nozzle  720 , a controller  704 , first and second brushrolls  704 - 1 ,  704 - 2 , first and second motors  706 - 1 ,  706 - 2 , an optional floor-type sensor  724 , and optional first and second wheels  708 - 1 ,  708 - 2 . 
     The first and second brushrolls  704 - 1 ,  704 - 2  are disposed substantially coaxial relative to each other and can be driven independently by first and second motors  706 - 1 ,  706 - 2 , respectively. The controller  704  may be implemented similar to that of the controller  104  (See  FIG. 1A ), and in addition, the controller  704  may implement the force-sensing features as previously discussed to receive user input and convert the same into control commands. In any event, the controller  704  can independently control the speed and rotational direction of each of the first and second brushrolls  706 - 1 ,  706 - 2  based on the control commands interpreted from a force-sensing arrangement consistent with the present disclosure or from other suitable user inputs. 
     Some aspects of the brush-driven assist drive arrangement may be better understood by way of example. Consider a scenario where a user desires that the vacuum device  700  veers/turns to the left during a cleaning operation. In this scenario, the controller  704  can send a first signal to the first motor  706 - 1  to cause the same to increase rotational speed or otherwise maintain a current rotational speed. The controller  704  can then send at substantially the same instance in time a second signal to the second motor  706 - 2  to cause the same to reduce rotational speed. The resulting differential rotational speed between the first and second brushrolls  704 - 1 ,  704 - 2  then causes the same to “draw” or otherwise cause the vacuum device  700  to generate a turning moment based on frictional communication with the surface to be cleaned. This turning moment thus causes the vacuum device  700  to veer/turn towards direction V 1 . The vacuum  700  can generate a turning moment towards the opposite direction, V 2 , by sending opposite signals such that the second brushroll  704 - 2  is driven by a signal to cause a higher rotational speed than that of the rotational speed of the first brushroll  704 - 1 . Note, the vacuum device  700  can include additional motors to optionally drive the first and second wheels  708 - 1 ,  708 - 2  during turning moments to further assist a user when they desire a change in direction during cleaning operations. 
     In an embodiment, the floor-type sensor  724  can determine a floor type (e.g., wood, carpet, tile). One example sensor suitable for use as the floor-type sensor  724  includes proximity sensors. The floor-type sensor  724  can then output a signal representative of the detected floor type. The controller  104  can receive the output signal from the floor-type sensor  724  and change operation of the vacuum device  700 . For example, the controller  104  may disable the brushroll drive assistance if the detected floor type is wood or otherwise substantially flat. In this instance, a floor type of wood may provide an insufficient amount of friction to utilize the brushroll drive assistance. On the other hand, the controller  104  may cause the first and second brushrolls  704 - 1 ,  704 - 2  via a mechanical lift arrangement (not shown) to extend towards the surface to be cleaned to cause the first and second brushrolls  704 - 1 ,  704 - 2  to engage with the same. Thus, based on the detected floor type the controller  104  may raise or lower the nozzle  720  and/or the first and second brushrolls  704 - 1 ,  704 - 2  relative to the surface to be cleaned in order to decrease or increase frictional communication with the same. 
     In another example, the controller  104  may detect carpet and reduce the rotational speed of the first and second brushrolls  704 - 1 ,  704 - 2  when performing brushroll drive assistance as the amount of friction between the brushrolls and the carpet fibers can be significantly greater than that of other surface types such as rug-type surface types. Alternatively, or in addition, the controller  104  may raise the first and second brushrolls  704 - 1 ,  704 - 2 , via the mechanical lift arrangement to reduce frictional communication with the surface to be cleaned. 
     Accordingly, a surface cleaning device consistent with the present disclosure can perform cleaning operations on a wide variety of floor types and adjust the frictional contact between the first and second rollers  704 - 1 ,  704 - 2  and the surface to be cleaned to ensure relatively consistent brushroll-aided movement and user experience when transitioning between multiple different floor types. 
       FIG. 8  shows an example robotic vacuum  800  implemented with a brushroll-assisted drive system consistent with an embodiment of the present disclosure. The robotic vacuum  800  is shown in a highly simplified form for ease of description and clarity. The robot vacuum  800  includes a housing  810 , first and second brushrolls  804 - 1 ,  804 - 2 , a controller  804 , first and second motors  806 - 1 ,  806 - 2 , an optional floor type sensor  824 , and an optional pivot wheel  808 . The robotic vacuum  800  includes a configuration substantially similar to that of the vacuum device  700 , and to this end the teachings of the vacuum device  700  discussed above are equally applicable to the robotic vacuum  800  and will not be repeated for brevity. However, the embodiment of  FIG. 8  includes first and second brushrolls  804 - 1 ,  804 - 2  that extend substantially across the diameter of the housing  810  in a so-called “full width” configuration. In addition, the first and second brushrolls  804 - 1 ,  804 - 2  extend substantially across the center of the housing  810 . 
       FIGS. 9A-9D  show additional example embodiments of brushroll configurations in accordance with aspects of the present disclosure. The brushroll configurations  900 A- 900 D may be utilized in embodiments disclosed herein including, for example, the vacuum device of  FIG. 1B-1C , the robotic vacuum devices of  FIG. 6A-6B  and  FIG. 8 . 
     Turning to  FIG. 9A , a brushroll configuration  900 A is shown consistent with an embodiment of the present disclosure. In this embodiment, the first and second brushrolls  904 - 1 ,  904 - 2 , include a substantially conical shape and are configured to direct hair and debris towards the tapered ends of each brushroll, and ultimately to the gap disposed therebetween that transitions into the dirty air inlet  129 . 
       FIG. 9B  shows a brushroll configuration  900 B consistent with an embodiment of the present disclosure. As shown, the brushroll configuration  900 B includes first and second brushrolls  904 - 1 ,  904 - 2  having a substantially conical shape. In the embodiment of  FIG. 9B , the first and second brushrolls  904 - 1 ,  904 - 2  include an overlapping configuration whereby the first and second brushrolls  904 - 1 ,  904 - 2  include longitudinal center lines that extend substantially parallel to each other. This results in a relatively uniform gap that extends between the first and second brushrolls  904 - 1 ,  904 - 2 . In addition, the imaginary line representing the longitudinal centerline of each brushroll also denotes a point of contact with the surface to be cleaned. 
       FIG. 9C  shows another example brushroll configuration  900 C consistent with an embodiment of the present disclosure. As shown, the first and second brushrolls  904 - 1 ,  904 - 2  are aligned similar to the brushroll configuration  900 B, but without a gap extending therebetween. Thus, the bristles/projections of the first and second brushrolls  904 - 1 ,  904 - 2 , interact with each other in gear-like fashion to trap and drive hair and debris towards the dirty air inlet  129 . The imaginary line that indicates the longitudinal center line of each of the first and second brushrolls  904 - 1 ,  904 - 2 , indicates a point of contact with the surface to be cleaned. 
       FIG. 9D  shows yet another example brushroll configuration  900 D consistent with an embodiment of the present disclosure. As shown, the first and second brushrolls  904 - 1 ,  904 - 2  include a substantially conical shape and bristles that form a helical or screw-like pattern. In addition, a gap extends between the first and second brushrolls  904 - 1 ,  904 - 2 . 
     In accordance with an aspect of the present disclosure a surface cleaning device is disclosed. The surface cleaning device including a base including a nozzle to receive dirt and debris, an upright portion coupled to the base including a handle to be gripped by a user, a force sensor arrangement including at least first and second load cells coupled to the base, the first and second load cells to receive user input during operation of the surface cleaning device and output first and second measurement signals, respectively, and a controller to identify a force applied by the user based on the first and second measurement signals, the controller further to determine a target direction of travel for the surface cleaning device based on the identified force. 
     In accordance with another aspect of the present disclosure a surface cleaning device is disclosed. The surface cleaning device comprising a swivel base including a nozzle configured to receive dirt and debris, the swivel base having first and second projections extending therefrom that extend substantially parallel relative to each other, an upright portion coupled to the swivel base, the upright portion including a handle to be gripped by a user, and a force sensor arrangement including at least first and second load cells, each of the first and second load cells having an opening to receive the first or second projection, and a sensor to output a force measurement value representative of an amount of force applied by the first or second projection to the sensor in response to the user applying force to the handle. 
     In accordance with another aspect of the present disclosure a surface cleaning is disclosed. The surface cleaning device comprising a housing having a motor disposed therein to generate suction and a dust cup for storing dirt and debris, a dirty air inlet disposed in the housing for receiving dirt and debris via the generated suction, at least first and second brushrolls disposed proximate the dirty air inlet to agitate the dirt and debris on a surface to be cleaned, at least first and second motors to drive the first and second brushrolls, respectively, and a controller to cause the first motor to drive the first brushroll at a first rotational speed and to cause the second motor to drive the second brushroll a second rotational speed, the first rotational speed being different from the second rotational speed to cause the surface cleaning device to rotate or change a direction of travel. 
     In accordance with another aspect of the disclosure a surface cleaning device is disclosed. The surface cleaning device comprising a housing having a motor disposed therein to generate suction and a dust cup for storing dirt and debris, a dirty air inlet disposed in the housing for receiving dirt and debris via the generated suction, at least first and second brushrolls disposed proximate the dirty air inlet to agitate the dirt and debris on a surface to be cleaned, at least first and second motors to drive the first and second brushrolls, respectively, and a controller to cause the first motor to drive the first brushroll at a first rotational speed and to cause the second motor to drive the second brushroll a second rotational speed, the first rotational speed being different from the second rotational speed to cause the surface cleaning device to rotate or change a direction of travel. 
     The surface cleaning device can further comprise a surface type detector to detect a surface type of the surface to be cleaned, and wherein the controller is further to extend the first and second brushrolls towards the surface to be cleaned or to retract the first and second brushrolls away from the surface to be cleaned based on the detected surface type. The surface cleaning device can further have the first and second brushrolls extending substantially coaxial relative to each other. The first and second brushrolls can have a substantially conical shape. The surface cleaning device can be implemented as a robotic vacuum device. 
     While the principles of the disclosure 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 disclosure. Other embodiments are contemplated within the scope of the present disclosure 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 disclosure, which is not to be limited except by the following claims.