Mobile Cleaning Robot Suspension

Abstract

The mobile cleaning robot may be movable within an environment, the mobile cleaning robot may include a body, a drive wheel arm, a drive wheel, a cam, and a cam follower. The drive wheel arm may be coupled to the body and may be movable relative to the body between an extended position and a retracted position. The drive wheel may be coupled to the drive wheel arm and may be movable with the drive wheel arm. The drive wheel may be operable to move the mobile cleaning robot. The cam may be coupled to the drive wheel arm and may be movable with the drive wheel arm. The cam follower may be coupled to the body and may be engaged with the cam to move the drive wheel arm towards the extended position.

Description

[Technical field]

[0001] Priority Application This application is a continuation of and claims priority to U.S. Patent Application No. 17 / 682,021, filed February 28, 2022, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] Mobile robots include mobile cleaning robots that can perform cleaning tasks within an environment, such as a home. The mobile cleaning robots navigate across a floor surface and avoid obstacles while vacuuming the floor surface and operating a rotatable member supported by the robot to suck debris from the floor surface. As the robot moves across the floor surface, the robot can rotate the rotatable member, which can engage debris and direct it toward a vacuum airflow generated by the robot, such that the rotatable member and the vacuum airflow cooperate to allow the robot to suck up the debris. Summary of the Invention [Problem to be solved by the invention]

[0003] Mobile cleaning robots can autonomously navigate through an environment to perform cleaning operations, often over and around obstacles. Mobile cleaning robots include a suspension system to provide sufficient wheel downforce to overcome obstacles and provide effective cleaning for various surfaces. Because obstacles can vary in shape and size, and floor types can also vary, the wheel downforce required during the robot's operation can vary. Many robots include suspension systems that use extension or compression springs directly connected to the wheel arms, which can effectively deliver downforce, but the delivered downforce can decay as the drive wheels extend from the body, delivering an undesirable downforce profile. [Means for solving the problem]

[0004] This disclosure describes devices and methods that can help address this issue, such as by including a suspension system that includes a cam and a cam follower. The cam and cam follower can be coupled to a biasing element to indirectly transmit force to the wheels to provide downforce. Because the cams can be designed in different shapes, the suspension system can be adjusted to provide a desired wheel downforce over a range of wheel extensions from the robot's body, helping to improve the object traversal and cleaning efficiency of the mobile cleaning robot and also helping to reduce cost between robot model variations.

[0005] For example, the mobile cleaning robot may include a body, a drive wheel arm, a drive wheel, a cam, and a cam follower. The drive wheel arm may be coupled to the body and may be movable between an extended position and a retracted position relative to the body. The drive wheel may be coupled to the drive wheel arm and may be movable with the drive wheel arm. The drive wheel may be operable to move the mobile cleaning robot. The cam may be coupled to the drive wheel arm and may be movable with the drive wheel arm. The cam follower may be coupled to the body and may be engaged with the cam to move the drive wheel arm towards the extended position.

[0006] In the drawings, which are not necessarily drawn to scale, like numerals may describe like components in different figures. Like numerals with different subscripts may represent different instances of like components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 illustrates a top view of a mobile cleaning robot within an environment. [Figure 2A] FIG. 2 shows a bottom view of the mobile cleaning robot. [Figure 2B] An isometric view of a mobile cleaning robot is shown. [Diagram 3] 2B shows a cross-sectional view of the mobile cleaning robot taken across indicator 3-3 of FIG. 2A. [Figure 4A] 1 illustrates a cross-sectional view of a portion of a mobile cleaning robot in a first state. [Figure 4B] 2 illustrates a cross-sectional view of a portion of the mobile cleaning robot in a second state. [Figure 4C] 1 illustrates a cross-sectional view of a portion of a mobile cleaning robot in a third state. [Figure 5A] FIG. 1 shows a schematic diagram of a mobile cleaning robot suspension system. [Figure 5B] FIG. 1 shows a schematic diagram of a mobile cleaning robot suspension system. [Figure 6] 1 shows a performance chart of a suspension system. [Figure 7] 1 shows a performance chart of a suspension system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Robot Overview FIG. 1 shows a plan view of a mobile cleaning robot 100 in an environment 40. The environment 40 may be a residential building, such as a house or apartment, and may include rooms 42a-42e. Objects, such as a bed 44, a table 46, and an island 48, may be located within the rooms 42 of the environment. Each of the rooms 42a-42e may have a floor surface 50a-50e, respectively. Some rooms, such as room 42d, may include a rug, such as rug 52. The floor surface 50 may be of one or more types, such as hardwood, ceramic, low pile carpet, medium pile carpet, long (or high) pile carpet, or stone.

[0009] The mobile cleaning robot 100 can be operated, such as by a user 60, to autonomously clean the environment 40 in a room-by-room manner. In some examples, the robot 100 can clean the floor surface 50a in one room, such as room 42a, and then move to the next room, such as room 42d, to clean the surfaces in room 42d. Different rooms can have different types of floor surfaces. For example, room 42e (which can be a kitchen) can have a hard floor surface, such as wood or ceramic tile, and room 42a (which can be a bedroom) can have a carpet surface, such as medium pile carpet. Other rooms, such as room 42d (which can be a dining room), can include multiple surfaces, with a rug 52 located within room 42d. The robot 100 can be configured to navigate over various floor types via one or more components, such as suspension. The robot's suspension can also enable the robot 100 to navigate over obstacles, such as thresholds between rooms, or over rugs, such as rug 52.

[0010] Also, during cleaning or navigation operations, the robot 100 can build up a map of the environment 40 using data collected from various sensors (such as optical sensors) and calculations (such as odometry and obstacle detection). Once the map is created, the user 60 can define rooms or zones (such as room 42) within the map. The map can be presented to the user 60 on a user interface, such as a mobile device, where the user 60 can, for example, indicate or change cleaning preferences.

[0011] Also, during operation, the robot 100 can detect the surface types within each of the rooms 42, which can be stored on the robot or another device. The robot 100 can update the map (or data associated therewith), such as to include or take into account the surface types of each floor surface 50a-50e of each respective room 42 of the environment. In some examples, the map can be updated to show different surface types, such as within each of the rooms 42.

[0012] Robot components FIG 2A shows a bottom view of the mobile cleaning robot 100. FIG 2B shows a bottom view of the mobile cleaning robot 100. FIG 3 shows a cross-sectional view of the mobile cleaning robot 100 across indicator 3-3 of FIG 2A. FIG 3 also shows orientation indicators bottom, top, front, and back. FIG 2A-FIG 3 are discussed together below.

[0013] The cleaning robot 100 may be a mobile cleaning robot capable of autonomously traversing the floor surface 50 while sucking up debris 75 from different parts of the floor surface 50. As shown in FIG. 2A and FIG. 3, the robot 100 may include a body 200 that is movable across the floor surface 50. The body 200 may include a number of articulated structures to which the movable components of the cleaning robot 100 may be attached. The articulated structures may include an outer housing that covers the internal components of the cleaning robot 100, a chassis to which the drive wheels 210a and 210b and the cleaning rollers 205a and 205b (of the cleaning assembly 205) are attached, and a bumper 138 attached to the outer housing.

[0014] As shown in FIG. 2A, the body 200 may include a front portion 202a having a generally semicircular shape and a rear portion 202b having a generally semicircular shape. As shown in FIG. 2A, the robot 100 may include a drive system including actuators 208a and 208b, e.g., motors, operable with drive wheels 210a and 210b. The actuators 208a and 208b may be mounted within the body 200 and operably coupled to the drive wheels 210a and 210b, which are rotatably mounted to the body 200. The drive wheels 210a and 210b may support the body 200 above a floor surface 50. The actuators 208a and 208b, when actuated, may rotate the drive wheels 210a and 210b to enable the robot 100 to move across the floor surface 50.

[0015] The controller (or processor) 212 may be located within the housing 200 and may be a programmable controller, such as a single-board or multi-board computer, a direct digital controller (DDC), or a programmable logic controller (PLC), etc. In other examples, the controller 212 may be any computing device, such as a handheld computer, e.g., a smartphone, a tablet, a laptop, a desktop computer, or any other computing device that includes a processor and communication capabilities. The memory 213 may be one or more types of memory, such as volatile or non-volatile memory, read-only memory (ROM), random access memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, and other storage devices and media. The memory 213 may be located within the housing 200 and may be coupled to and accessible by the controller 212.

[0016] The controller 212 can operate the actuators 208a and 208b to autonomously navigate the robot 100 across the floor surface 50 during cleaning operations. The actuators 208a and 208b are operable to drive the robot 100 in a forward drive direction, a rearward drive direction, and to turn the robot 100. The robot 100 can include caster wheels 211 (or alternatively skids) that support the body 200 above the floor surface 50. The casters 211 can support the front portion 202b of the body 200 above the floor surface 50, and the drive wheels 210a and 210b support the middle and rear portions 202a of the body 200 above the floor surface 50.

[0017] As shown in FIG. 3, the vacuum assembly 118 may be located within the body 200 of the robot 100, for example, in the middle of the body 200. The controller 212 may operate the vacuum assembly 118 to generate an airflow that passes through the body 200 and out of the body 200 through an air gap near the cleaning roller 205. The vacuum assembly 118 may include, for example, an impeller that generates the airflow when rotated. When rotated, the airflow and the cleaning roller 205 cooperate to suck debris 75 into the robot 100. A cleaning bin 322 may be mounted within the body 200 to contain debris 75 sucked in by the robot 100, and a filter within the body 200 separates the debris 75 from the airflow 120 before the airflow 120 enters the vacuum assembly 118 and is exhausted from the body 200. In this regard, the debris 75 is captured in both the cleaning bin 322 and the filter before the airflow 120 is exhausted from the body 200.

[0018] The cleaning rollers 205a and 205b may be operably coupled to actuators 214a and 214b, e.g., motors, respectively. The cleaning head 205 and cleaning rollers 205a and 205b may be positioned in front of the cleaning bin 322. The cleaning rollers 205a and 205b are attached to the housing 124 of the cleaning head 205, and may be attached, e.g., indirectly or directly, to the body 200 of the robot 100. For example, the cleaning rollers 205a and 205b may be attached to the underside of the body 200 such that the cleaning rollers 205a and 205b engage debris 75 on the floor surface 50 during a cleaning operation when the underside faces the floor surface 50.

[0019] The housing 124 of the cleaning head 205 may be attached to the body 200 of the robot 100. In this manner, the cleaning rollers 205a and 205b may also be attached to the body 200 of the robot 100, for example indirectly attached to the body 200 via the housing 124. The cleaning head 205 may also be a removable assembly of the robot 100, where the housing 124 with the cleaning rollers 205a and 205b mounted therein is removably attached to the body 200 of the robot 100. The housing 124 and the cleaning rollers 205a and 205b may be removable from the body 200 as a unit, such that the cleaning head 205 is easily replaceable with a replacement cleaning head 205.

[0020] The control system may further include a sensor system having one or more electrical sensors. As described herein, the sensor system may generate signals indicative of the current location of the robot 100 and may generate signals indicative of the location of the robot 100 as it travels along the floor surface 50.

[0021] Cliff sensors 134 (shown in FIG. 2A ) may be located along a bottom portion of housing 200. Each of cliff sensors 134 may be an optical sensor that may be configured to detect the presence or absence of an object below the optical sensor, such as floor surface 50. Cliff sensors 134 may be coupled to controller 212. Bumper 138 may be removably secured to body 200 and may be movable relative to body while attached to body 200. In some examples, bumper 138 forms part of body 200. Bump sensors 139a and 139b (bump sensors 139) may be coupled to body 200 and may be engageable with or configured to interact with bumper 138. Bump sensor 139 may include a break beam sensor, a capacitance sensor, a switch, or other sensor capable of detecting contact between robot 100, i.e., bumper 138, and an object in environment 40. Bump sensor 139 may be in communication with controller 212.

[0022] The image capture device 140 may be a camera coupled to the body 200 and may extend through the bumper 138 of the robot 100, such as through an opening 143 in the bumper 138. The image capture device 140 may be a camera, such as a front camera, configured to generate signals based on images of the environment 40 of the robot 100 as the robot 100 moves across the floor surface 50. The image capture device 140 may send signals to the controller 212 for use in navigation and cleaning routines.

[0023] The obstacle following sensor 141 (shown in FIG. 2B) may include an optical sensor that may be configured to detect the presence or absence of an object facing outward from the bumper 138 and adjacent to the side of the body 200. The obstacle following sensor 141 may emit a light beam horizontally in a direction perpendicular (or nearly perpendicular) to the forward drive direction of the robot 100. The light emitter may emit the light beam outward from the robot 100, e.g., horizontally outward, and the light detector detects the reflection of the light beam reflecting off an object near the robot 100. The robot 100, e.g., using the controller 212, may determine the time of flight of the light beam, thereby determining the distance between the light detector and the object, and therefore the distance between the robot 100 and the object.

[0024] The side brushes 142 may be coupled to an underside of the robot 100 and may be coupled to a motor 144 operable to rotate the side brushes 142 relative to the body 200 of the robot 100. The side brushes 142 may be configured to engage debris and move the debris toward the cleaning assembly 205 or away from the edge of the environment 40. The motor 144 configured to drive the side brushes 142 may be in communication with the controller 112. The brushes 142 may rotate about a non-horizontal axis, for example, an axis that forms an angle of 75 degrees to 90 degrees with the floor surface 50. The non-horizontal axis may, for example, form an angle of 75 degrees to 90 degrees with the longitudinal axes 126a and 126b of the rollers 205a and 205b.

[0025] Brush 142 may be a side brush that is offset laterally from the center of robot 100 such that brush 142 may extend beyond the perimeter of body 200 of robot 100. Similarly, brush 142 may also be offset forwardly from the center of robot 100 such that brush 142 extends beyond bumper 138. Optionally, robot 100 may include multiple side brushes, such as side brushes located on either side of body 200, such as in line with drive wheels 210a and 210b, respectively.

[0026] The robot 100 may also include a button 146 (or interface), which may be a user-operable interface configured to provide instructions to the robot, such as to pause the mission, power on, power off, or return to a docking station. The robot 100 may also include a privacy button 148 (or interface), which may be a user-operable interface configured to provide instructions to the robot, such as to disable or limit use of the camera 140. For example, pressing the privacy button 148 may turn off the camera 140 or operate the shutter 152 to close or open. An indicator 150 may be optionally included and may be illuminated to indicate when the camera 140 is operating. Additional privacy controls and options are discussed in more detail below in connection with FIGS. 4A-6.

[0027] Robot movement In some example operations, the robot 100 may be propelled in a forward drive direction or a backward drive direction. The robot 100 may also be propelled such that the robot 100 turns in place or turns while moving in a forward drive direction or a backward drive direction.

[0028] When the controller 212 causes the robot 100 to perform a mission, the controller 212 can operate the motors 208 to drive the drive wheels 210 to propel the robot 100 along the floor surface 50. Additionally, the controller 212 can operate the motors 214 to rotate the rollers 205a and 205b, the motors 144 to rotate the brushes 142, and the motors of the vacuum system 118 to generate airflow. The controller 212 can execute software stored on the memory 213 to operate the various motors of the robot 100 to cause the robot 100 to perform various navigation and cleaning behaviors.

[0029] Various sensors of the robot 100 may be used to help the robot navigate and clean within the environment 40. For example, the cliff sensor 134 may detect obstacles such as steep slopes and cliffs on a lower portion of the robot 100 on which the cliff sensor 134 is disposed. The cliff sensor 134 may send a signal to the controller 212 such that the controller 212 may redirect the robot 100 based on the signal from the cliff sensor 134.

[0030] In some examples, bump sensor 139a can be used to detect movement of bumper 138 along the front-to-back axis of robot 100. Bump sensor 139b can also be used to detect movement of bumper 138 along one or more sides of robot 100. Bump sensor 139 can send a signal to controller 212 such that controller 212 can turn robot 100 based on the signal from bump sensor 139.

[0031] The image capture device 140 may be configured to generate signals based on images of the environment 40 of the robot 100 as the robot 100 moves across the floor surface 50. The image capture device 140 may transmit such signals to the controller 212. The image capture device 140 may be angled upward, for example, between 5 degrees and 45 degrees from the floor surface 50 across which the robot 100 navigates. When angled upward, the image capture device 140 may capture images of wall surfaces of the environment such that features corresponding to objects on the wall surfaces can be used for localization.

[0032] In some examples, the obstacle-following sensors 141 can detect detectable objects including obstacles such as furniture, walls, people, and other objects in the environment of the robot 100. In some implementations, the sensor system can include obstacle-following sensors along the sides, which can detect the presence or absence of objects adjacent to the sides. One or more of the obstacle-following sensors 141 can also function as obstacle detection sensors, similar to the proximity sensors described herein.

[0033] The robot 100 may also include sensors to track the distance traveled by the robot 100. For example, the sensor system may include an encoder associated with the motor 208 for the drive wheels 210, which can track the distance traveled by the robot 100. In some implementations, the sensor may include an optical sensor that faces down toward the floor surface. The optical sensor may be positioned to direct light through the bottom surface of the robot 100 toward the floor surface 50. The optical sensor may detect reflections of light and can detect the distance traveled by the robot 100 based on changes in floor features as the robot 100 travels along the floor surface 50.

[0034] The controller 212 can use data collected by the sensors of the sensor system to control the navigation behavior of the robot 100 during a mission. For example, the controller 212 can use sensor data collected by the obstacle detection sensors (cliff sensors 134, bump sensors 139, and image capture device 140) of the robot 100 to enable the robot 100 to avoid obstacles in the environment of the robot 100 during a mission.

[0035] The sensor data may also be used by the controller 212 for self-localization and environment mapping (SLAM) techniques, in which the controller 212 extracts features of the environment represented by the sensor data and builds a map of the floor surface 50 of the environment. The sensor data collected by the image capture device 140 may be used for techniques such as vision-based SLAM (VSLAM), in which the controller 212 extracts visual features corresponding to objects in the environment 40 and builds a map using these visual features. As the controller 212 guides the robot 100 throughout the floor surface 50 during a mission, the controller 212 may use SLAM techniques to determine the location of the robot 100 within the map by detecting features represented in the collected sensor data and comparing the features to previously stored features. The map formed from the sensor data may indicate the location of traversable and non-traversable spaces within the environment. For example, the location of obstacles may be indicated on the map as non-traversable spaces and the location of open floor spaces may be indicated on the map as traversable spaces.

[0036] Sensor data collected by any of the sensors may be stored in memory 213. Additionally, other data generated for the SLAM technique may be stored in memory 213, including mapping data forming a map. These data generated during a mission may include persistent data generated during a mission and usable during further missions. In addition to storing software for causing the robot 100 to perform the behaviors of the robot 100, the memory 213 may store data resulting from the processing of the sensor data for access by the controller 212. For example, a map may be a map usable and updatable by the controller 212 of the robot 100 to navigate the robot 100 through the floor surface 50 from one mission to another.

[0037] The persistent data, including the persistent map, helps enable the robot 100 to efficiently clean the floor surface 50. For example, the map allows the controller 212 to guide the robot 100 towards open floor spaces and avoid untraversable spaces. Additionally, in subsequent missions, the controller 212 may use the map, which may help optimize the path taken during the mission to plan the navigation of the robot 100 through the environment 40.

[0038] Suspension example FIG. 4A shows a cross-sectional view of a portion of the mobile cleaning robot 400 in a first state. FIG. 4B shows a cross-sectional view of a portion of the mobile cleaning robot 400 in a second state. FIG. 4C shows a cross-sectional view of a portion of the mobile cleaning robot 400 in a third state. FIGs. 4A-4C are discussed together below. The mobile cleaning robot 400 may be similar to the robot 100 described above. FIGs. 4A-4C show that the mobile cleaning robot 400 may include a cam-based suspension system. Any of the robots described above or below may be modified to include such a suspension.

[0039] More specifically, the mobile cleaning robot 400 may include a body 402 supported by drive wheels 412 (only one wheel is visible in FIGS. 4A-4C ) and skids 411. Optionally, the skids 411 may be replaced with casters. The mobile cleaning robot 400 may also include a suspension system 454 coupled to the body 402 and coupled to the drive wheels 412. The suspension system 454 may be configured to control or determine the downforce exerted by the wheels 412.

[0040] The suspension system 454 may include a drive wheel arm 456, a cam 458, a cam follower assembly 460, and a spring assembly 462 (or biasing assembly). The drive wheel arm 456 may be coupled to the body 402 and may be movable relative to the body 402 between an extended position (as shown in FIG. 4C) and a retracted position (as shown in FIG. 4A). The drive wheel arm 456 may be coupled to the body 402 at a pivot 464 that may allow the drive wheel arm 456 and the drive wheel 412 to pivot relative to the body 402. The drive wheel arm 456 may support a drive train 466 coupled to the drive wheel 412 and configured to drive and rotate the drive wheel 412.

[0041] The cam 458 may be coupled to the drive wheel arm 456 and may be movable therewith. The cam 458 may optionally include a protrusion 468 insertable into a slot 470 (numbered in FIG. 4A ) in the drive wheel arm 456, such as a dovetail configuration. This configuration may allow the cam 458 to be easily interchangeable to achieve different cam profiles, as discussed in more detail below. The cam 458 may define a cam surface 472 that may be contoured to engage a cam follower assembly 460 to move the drive wheel arm 456 toward the extended position while simultaneously achieving a desired downforce profile of the drive wheel 412 through such range of movement.

[0042] Cam follower assembly 460 may include a cam arm 474, a cam follower 476, and a pin 478. Cam arm 474 may be a rigid or semi-rigid member that may be coupled to cam follower 476 via pin 478, such as to support rolling of cam follower 476 relative to cam arm 474. The rolling of cam follower 476 may allow cam follower 476 to rotationally follow cam surface 472. Cam arm 474 may be coupled to body 402 via pivot 480, such as to allow cam follower assembly 460 to pivot relative to body 402.

[0043] The pin 478 may be a solid pin configured to act as a journal bearing for the cam follower 476 (optionally, the pin 478 may be a rolled pin or a hollow pin). The pin 478 may be other bearings, such as a ball bearing system in other examples. The pin 478 may have an outer diameter of 0.5 millimeters (mm) to 10 mm, such as 1 mm to 3 mm. The pin 478 may be made of one or more of a metal, a polymer, or a ceramic, and the like. For example, the pin 478 may be a polished steel pin. The pin 478 may optionally be coated to reduce friction between the cam follower 476, the pin 478, and the cam arm 474. The pin 478 may be supported by a hole in the cam arm 474 and secured to the hole, such as in a press fit arrangement, to form a rolling contact or engagement between the pin 478 and the cam follower 476. Optionally, pin 478 may be fixed to cam follower 476 to form a rolling contact or engagement between pin 478 and cam arm 474. Optionally, pin 478 may be fixed in a variety of other ways such that pin 478 can rotate relative to cam arm 474 and cam follower 476 can rotate relative to pin 478.

[0044] Optionally, pin 478, holes in cam arm 474, or cam follower 476 may be coated with polytetrafluoroethylene (PTFE) or the like to reduce friction between the components. Similarly, cam surface 472 may optionally be coated or made of a low-friction material, such as a polymer-based material (such as nylon) or ceramic.

[0045] Cam follower 476 may be a wheel, disk, roller, or the like configured to form a rolling contact surface between cam surface 472 and cam follower 476. Cam follower 476 may be made of a low friction material such as a polymer-based material (e.g., polyoxymethylene (POM), e.g., Delrin or other POM) or ceramic. Cam follower 476 may have a relatively larger outer diameter than pin 478 to reduce rolling friction. For example, the outer diameter of cam follower 476 may be between 5 mm and 30 mm. Optionally, the outer diameter of cam follower 476 may be between 10 mm and 20 mm, e.g., 13, 14, or 15 mm. The outer diameter of cam follower 476 may be maximized or optimized based on the contact between cam surface 472 and a portion of body 402 when drive wheel 412 is in a fully retracted or stored position.

[0046] The spring assembly 462 may include a biasing element 482 and optionally an extension tube 484. The biasing element 482 may be any biasing element, such as a tension spring, a compression spring, a spring bar, or a torsion spring. The biasing element 482 may be coupled to a pivot 488 to couple the spring assembly 462 to the body 402 such that the spring assembly 462 may pivot relative to the body 402. The biasing element 482 may also be directly or indirectly coupled to the cam arm 474. For example, the biasing element 482 may be coupled to the extension tube 484 at a spring coupling 486. The extension tube 484 may then be coupled to the cam arm 474 via a tube post 490 for pivotally coupling the extension tube 484 to the cam arm 474 to bias the drive wheel arm 412 toward the extended position and allow rotation of the spring assembly 462 relative to the cam arm 474, etc.

[0047] In some example operation, the suspension system 454 can apply a force to move the drive wheel 412 out of the body 402 to maintain downforce on the drive wheel 412, for example, as the drive wheel 412 moves between the retracted position shown in FIG. 4A, the partially extended position of FIG. 4B, and the fully extended position of FIG. 4C. While the use of springs coupled to the wheel arms (without cams) can effectively deliver downforce, the delivered downforce can decay as the drive wheel extends out of the body, delivering a less than desirable downforce profile for many operating conditions, such as navigating through high pile carpet. The design components and methods of the present application can help address these issues, such as by using cam follower assemblies 460 and cams 458 to vary the mechanical advantage as the drive wheel 412 is extended and retracted to achieve a desired downforce profile. For example, spring damping that occurs as the drive wheel 412 moves toward the extended position may be countered (or compensated for) by increasing the mechanical advantage between the cam follower assembly 460 and the cam 458 as the suspension system 454 moves with the drive wheel 412. Further operational details are provided below.

[0048] 4A, the drive wheel 412 may be in a retracted position. In the retracted position, the cam follower 476 may be pivoted upward and engaged with a rear portion of the cam surface 472 of the cam 458. In such a state or position, the biasing element 482 may be at or near its maximum extension because the extension tube 484 is near (or in contact with) the top of the body 402 of the mobile cleaning robot 400. However, due to the contact location of the cam follower 476 and the cam surface 472, the mechanical advantage between the cam follower assembly 460 and the cam 458 (delivering the force generated by the biasing element 482) may be relatively low.

[0049] As shown in FIG. 4B, the drive wheel 412 may be moved to a partially extended position, such as a position where the drive wheel 412 along with the skid 411 engages the floor, which may be, for example, a hard floor surface configuration or condition. In this position, the suspension system 454 may be rotated downward from its position in FIG. 4A, causing the cam follower 476 to roll forward on the cam surface 472, increasing the mechanical advantage between the cam arm 474 and the cam 458, helping to more effectively deliver force from the biasing element 482 to the drive wheel 412. This increase in mechanical advantage may offset the attenuation of force in the biasing element 482 caused by the decrease in the length L1 of the biasing element 482 from FIG. 4A to FIG. 4B.

[0050] As shown in FIG. 4C , the drive wheel 412 may be moved to a fully extended position where the drive wheel 412 engages the floor 50 but the skid 411 is elevated from the floor 50, which may be a configuration or state where the mobile cleaning robot 400 is navigating on a high pile carpet or traversing an obstacle. In this position in FIG. 4C , the suspension system 454 may be rotated further downward from its position in FIG. 4B , causing the cam follower 476 to roll further forward on the cam surface 472, increasing the mechanical advantage between the cam arm 474 and the cam 458, helping to more effectively deliver the force from the biasing element 482 to the drive wheel 412. This increase in mechanical advantage between the position in FIG. 4B and the position in FIG. 4C may further help counteract the attenuation of the force of the biasing element 482 caused by the decrease in the length L1 of the biasing element 482 from FIG. 4B to FIG. 4C , which may help maintain a constant or near-constant downforce between the positions in FIG. 4A to FIG. 4C .

[0051] This allows the suspension system 454 to deliver a constant (or undamped) downforce over the entire range of travel of the drive wheel 412. Although a constant downforce is discussed as being delivered by the suspension system 454, the suspension system 454 may also be adjusted or designed to deliver a desired downforce profile, for example, by changing the shape or profile of the cam surface 472 to change the mechanical advantage. For example, the cam surface 472 may be shaped to deliver a non-linear downforce to the drive wheel 412 as it moves between the extended and retracted positions. In other words, the cam surface 472 may be shaped to deliver a desired force profile over the range of travel of the drive wheel arm 456 between the extended and retracted positions.

[0052] Advantageously, the cam follower 476 can be separated from the cam 458 so that the drive wheel arm 456 and drive wheel 412 can be rotated away from the body without disconnecting components of the suspension system 454. This can aid in simplifying replacement of components of the suspension system 454 or the drive wheel 412, such as the tire tread.

[0053] Optionally, as shown in FIG. 4C , body 402 may include a stopper 492 engageable with cam arm 474 to limit downward movement of cam arm 474, thereby effectively limiting the application of a downward force to drive wheel arm 456 and thus drive wheel 412. Downward movement or motion of drive wheel 412 may optionally be limited by engagement between drive wheel arm 456 and a lower portion of drive wheel 412.

[0054] The extension tube 484 may allow a biasing element 482 to be used that is longer than the connection between the pivot 488 and the tube post 490. That is, the biasing element 482 and the extension tube 484 may extend beyond the connection point (tube post 490) between the extension tube 484 and the cam arm 474. In other words, the biasing element 482 may have a length L1 that is greater than the distance or length L2 between the connection point (pivot 488) of the cam arm 474 to the body 402 and the connection point (tube post 490) between the extension tube 484 and the cam arm 474.

[0055] Optionally, as discussed above, the cam 458 may be removable from the drive wheel arm 456 (via slot 470 and protrusion 468, as shown in FIG. 4A). Also, as discussed above, because the suspension system 454 is decoupled (not rigidly connected), the drive wheel arm 456 and drive wheel 412 may be easily rotated and removed from the body 402 for maintenance, etc. These features may allow a user, designer, customer, etc. to remove the cam 458 and install a cam with a different cam surface to change the downforce profile of the suspension system 454, such as to optimize for a floor type or to address a crossing issue. These features may also allow a user (or the like) to replace the tread of the drive wheel 412 or the drive wheel 412 itself. Optionally, multiple cams may be coupled to the drive wheel arm 456, and the cam arm 474 may be positionable to engage the cam follower 476 with a desired cam.

[0056] 5A and 5B show schematic diagrams of the mobile cleaning robot suspension system 554 of the robot 500 in a stored or retracted position and an extended position. Figures 5A and 5B are discussed together below. The suspension system 554 can be similar to the suspension system 454 described above, and Figures 5A and 5B show the components generally.

[0057] 5A and 5B show schematic diagrams of the connection of biasing element 582 to body 502 at pivot 588. Biasing element 582 may be coupled to cam arm 574 at tube post 590 (acting as a pivot). Cam arm 574 may be coupled to body 502 at pivot 580, where cam arm 574 may be coupled to cam follower 576 via pin 578. At the other end, drive wheel arm 556s (schematic representation of an effective drive wheel arm) may be coupled to body 502 at pivot 564 and to drive wheel 512 at wheel center 594. Drive wheel arm 556s may be decoupled from cam arm 574, but engaged with cam arm 574 via cam follower 576. 5A and 5B also show various forces generated by the interaction of components, where N is the normal force perpendicular or tangential to the point of contact between the cam surface 572 of the cam 558 and the cam follower 576. M1 may be the moment arm of the biasing element 582 and the cam arm 574, and M2 may be the moment arm of the drive wheel arm 556s.

[0058] 5A shows that when drive wheel 512 is in the retracted position, biasing element 582 is relatively long, causing a large spring force S1 to be applied to cam arm 574. However, because the contact angle between cam followers 576 and 572 is relatively horizontal, moment arm M1 is relatively small (or similar in size) relative to moment arm M2, resulting in a first mechanical advantage and a first wheel downforce D1.

[0059] 5B shows that when the drive wheel 512 is in the extended position, the biasing element 582 is relatively shorter than in the retracted position of FIG. 5A, thereby applying a smaller force to the cam arm 574. However, because the contact angle between the cam follower 576 and the cam surface 572 is relatively vertical and the cam follower 576 has moved forward, the moment arm M1 in FIG. 5B is larger than the moment arm M2 (and compared to the moment arm M1 in FIG. 5A), resulting in a second mechanical advantage that is larger than the first mechanical advantage. Because the second mechanical advantage is larger than the first mechanical advantage and the second spring force S2 is smaller than the first spring force S1, the second wheel downforce D2 can be approximately the same as the first wheel downforce D1, helping to achieve a relatively consistent wheel downforce throughout the range of motion of the drive wheel 512 relative to the body 502.

[0060] Although downforces D1 and D2 are discussed and shown as being relatively constant (due at least in part to the shape of cam surface 572), cam surface 572 may be designed, shaped, or configured to provide a desired downforce at any position throughout the range of motion of drive wheel 512. In this manner, robot 500 (as well as robots 100 and 500) may include a passive suspension system that includes a tuned wheel downforce profile.

[0061] In some examples, the downforce exerted by the suspension system 554 or the robot suspension system 554 may be between 2 and 3.2 pounds (4.9 Newtons (N) to 14.25 N). In other examples, the suspension system 554 or the mobile cleaning robot suspension system 554 may provide between 1 N and 30 N.

[0062] Suspension performance Figure 6 shows a performance chart 600 of a suspension system, such as a mobile cleaning robot 400 or robot 500, where the suspension system has a first cam profile. Figure 7 shows a performance chart 700 of a suspension system, such as a mobile cleaning robot 400 or robot 500, where the suspension system has a second cam profile. Figures 6 and 7 are discussed together below.

[0063] Performance charts 600 and 700 each show wheel downforce on the Y or vertical axis and wheel lift or movement above the ground on the X or horizontal axis. Chart 600 shows the calculated (or theoretical) downforce 602, the measured downforce 604 provided by the drive wheel (e.g., 412) as it extends from the robot, and the measured downforce 606 provided by the drive wheel as it retracts into the robot, for a first cam profile. The theoretical plot 602 will likely not fall approximately halfway between the two hysteresis plots 604 and 606 (the same springs were used to collect data for both cam configurations). Chart 700 shows the calculated (or theoretical) downforce 702, the measured downforce 704 provided by the drive wheel (e.g., 412) as it extends from the robot, and the measured downforce 706 provided by the drive wheel as it retracts into the robot, for the second cam profile.

[0064] The first cam profile (or cam surface shape) of chart 600 shows a calculated force 602 that has a slightly increasing slope as the rise approaches 0 mm rise (from -30 mm), peaks near 0 mm wheel rise, and decreases after retraction into the body (0 to 10 mm wheel rise). This cam profile can provide a relatively consistent wheel downforce (such as 60-75% of the robot's weight on the wheels) throughout the range of motion of the drive wheels and wheel arms, with hysteresis causing a difference between extension downforce 604 and retraction downforce 606.

[0065] The second cam profile (or cam surface shape) of chart 700 shows a relatively flat calculated force 702 with a large increase in force near 0 mm wheel rise, with the extension and retraction forces measured on both sides taking into account hysteresis. The second cam profile can be designed to deliver such a force profile to help reduce the problem of robot jumping as the robot crosses a threshold or other obstacle. Jumping is a phenomenon that can occur when the robot crosses an obstacle such as a threshold or small step, where because the step is at the forward portion of the drive wheel (near the pivot), a large downward force can be generated, causing the robot to lift off the ground considerably. This phenomenon can be limited or prevented by modifying the cam profile such that the downforce is reduced at a certain extension distance of the drive wheel.

[0066] While this profile only addresses some issues, it highlights that the cam profile (e.g., cam surface 472), along with other components of the suspension (e.g., biasing element 482, extension tube 484, and all pivot points) can be adjustable or designed to provide a passive suspension system with various wheel downforce profiles to address navigation issues or to help optimize navigation or cleaning performance.

[0067] Because the cams can be designed in a variety of shapes, the cam system can be adjusted to provide a desired wheel downforce for robots of any weight and desired force profile so that the cam system can be used on a variety of mobile cleaning robots, helping to commonize suspension components and reducing costs between robot model variations.

[0068] Notes and Examples The following non-limiting examples detail particular aspects of the present subject matter to, among other things, solve the problems and provide the benefits discussed herein.

[0069] Example 1 is a mobile cleaning robot movable within an environment, the mobile cleaning robot comprising: a body; a drive wheel arm coupled to the body and movable between an extended position and a retracted position relative to the body; a drive wheel coupled to the drive wheel arm and movable with the drive wheel arm, the drive wheel operable to move the mobile cleaning robot; a cam coupled to the drive wheel arm and movable with the drive wheel arm; and a cam follower coupled to the body and engaged with the cam to move the drive wheel arm toward the extended position.

[0070] In Example 2, the subject matter of Example 1 optionally includes a biasing member coupled to the body and the cam follower to bias the drive wheel arm toward the extended position.

[0071] In Example 3, the subject matter of Example 2 optionally includes a cam arm connecting the cam follower to the body, the biasing member being connected to the cam arm.

[0072] In Example 4, the subject matter of Example 3 optionally includes the cam follower being rotatable relative to the cam arm to rotationally follow the cam.

[0073] In Example 5, the subject matter of Example 4 optionally includes an extension tube coupled to the biasing member and the cam arm, connecting the biasing member to the cam arm.

[0074] In Example 6, the subject matter of Example 5 optionally includes the biasing member and the extension tube extending beyond a connection point between the extension tube and the cam arm.

[0075] In Example 7, the subject matter of any one or more of Examples 5-6 optionally includes the drive wheel arm being pivotally connected to the body, the cam arm being pivotally connected to the body, and the biasing member being pivotally connected to the body.

[0076] In Example 8, the subject matter of Example 7 optionally includes the extension tube being pivotally connected to the cam arm.

[0077] In Example 9, the subject matter of any one or more of Examples 3-8 optionally includes, wherein the body includes a stopper engageable with the cam arm to limit application of a downward force to the drive wheel arm.

[0078] In Example 10, the subject matter of any one or more of Examples 1-9 optionally includes the cam being shaped to deliver a non-linear downforce from the drive wheel as the drive wheel moves between the extended and retracted positions.

[0079] In Example 11, the subject matter of any one or more of Examples 1-10 optionally includes the cam being shaped to deliver a desired force profile over a range of movement of the drive wheel arm between the extended and retracted positions.

[0080] Example 12 is a suspension assembly for a mobile cleaning robot, the suspension assembly comprising: a drive wheel operable to move the mobile cleaning robot; a drive wheel arm connected to a body of the mobile cleaning robot and supporting the drive wheel, the drive wheel arm being movable between an extended position and a retracted position relative to the body; a cam connected to the drive wheel arm and movable with the drive wheel arm; and a cam follower connected to the body and engaged with the cam to move the drive wheel arm toward the extended position.

[0081] In Example 13, the subject matter of Example 12 optionally includes a biasing member coupled to the body and the cam follower to bias the drive wheel arm toward the extended position.

[0082] In Example 14, the subject matter of Example 13 optionally includes a cam arm connecting the cam follower to the body, the biasing member being connected to the cam arm.

[0083] In Example 15, the subject matter of Example 14 optionally includes an extension tube coupled to the biasing member and the cam arm, connecting the biasing member to the cam arm.

[0084] In Example 16, the subject matter of Example 15 optionally includes the biasing member having a length greater than a distance between a connection point of the biasing member to the body and a connection point of the extension tube to the cam arm.

[0085] In Example 17, the subject matter of Example 16 optionally includes the drive wheel arm being pivotally connected to the body, the cam arm being pivotally connected to the body, and the biasing member being pivotally connected to the body.

[0086] In Example 18, the subject matter of Example 17 optionally includes the extension tube being pivotally connected to the cam arm.

[0087] Example 19 is a mobile cleaning robot movable within an environment, the mobile cleaning robot comprising: a body; a drive wheel operable to move the mobile cleaning robot; a drive wheel arm coupled to the body and supporting the drive wheel, the drive wheel arm being movable between an extended position and a retracted position relative to the body; and a cam assembly coupled to the body and the drive wheel arm to deliver a desired force profile over a range of movement of the drive wheel arm between the extended position and the retracted position.

[0088] In Example 20, the subject matter of Example 19 optionally includes a biasing member coupled to the body and the cam follower to bias the drive wheel arm toward the extended position.

[0089] In Example 21, the subject matter of Example 20 optionally includes a cam arm connecting the cam follower to the body, the biasing member being connected to the cam arm.

[0090] In Example 22, the subject matter of Example 21 optionally includes the cam follower being rotatable relative to the cam arm to rotationally follow the cam.

[0091] In Example 23, the subject matter of Example 22 optionally includes an extension tube coupled to the biasing member and the cam arm, connecting the biasing member to the cam arm.

[0092] In Example 27, the apparatus or method of any one or any combination of Examples 1-23 may be optionally configured such that all of the recited elements or options are available for use or selection.

[0093] The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are also referred to herein as "examples." Such examples may include elements in addition to those shown or described. However, the inventors also contemplate examples in which only those elements shown or described are provided. Moreover, the inventors also contemplate examples that use any combination or permutation of these elements (or one or more aspects thereof) shown or described, either with respect to the particular example (or one or more aspects thereof) or with respect to other examples (or one or more aspects thereof) shown or described herein.

[0094] In the event of any conflicting usage between this document and any document so incorporated by reference, the usage in this document shall control. In this document, the terms "comprising" and "in which" are used as the plain English equivalents of the respective terms "comprising" and "wherein." Also, in the following claims, the terms "comprising" and "comprising" are open-ended, i.e., a system, device, article, composition, formulation, or process that includes elements in addition to those recited after such term in a claim shall still be considered within the scope of that claim.

[0095] The above description is illustrative and not restrictive. For example, the above examples (or one or more aspects thereof) may be used in combination with each other. Upon review of the above description, other embodiments may be used by one of ordinary skill in the art, and the like. The Abstract is provided to comply with 37 CFR §1.72(b) to enable the reader to quickly ascertain the nature of the technical disclosure. The Abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. This should not be construed as intending that an unclaimed disclosed feature is essential to any claim. Rather, the subject matter of the invention may lie in less than all features of a particular disclosed embodiment. Thus, it is contemplated that the following claims are incorporated into the Detailed Description as examples or embodiments, with each claim standing on its own as a separate embodiment, and that such embodiments can be combined with each other in various combinations or permutations. The scope of the invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. [Explanation of symbols]

[0096] 3-3 indicator, 40 environment, 42 room, 42a room, 42b room, 42c room, 42d room, 42e room, 44 bed, 46 table, 48 island, 50 floor, floor surface, 50a floor surface, 50b floor surface, 50c floor surface, 50d floor surface, 50e floor surface, 52 rug, 60 user, 75 debris, 100 mobile cleaning robot, 112 controller, 118 vacuum assembly, vacuum system, 120 air flow, 124 housing, 126a longitudinal axis, 126b longitudinal axis, 134 cliff sensor, 138 bumper, 139 bump sensor, 139a bump sensor, 139b bump sensor, 140 image capture device, camera, 141 obstacle following sensor, 142 Side brush, 143, opening, 144, motor, 146, button, 148, privacy button, 150, indicator, 152, shutter, 200, body, housing, 202a, front portion, 202b, rear portion, 205, cleaning assembly, cleaning roller, cleaning head, 205a, cleaning roller, 205b, cleaning roller, 208, motor, 208a, actuator, 208b, actuator, 210, drive wheel, 210a, drive wheel, 210b, drive wheel, 211, caster wheel, caster, 212, controller (or processor), 213, memory, 214, motor, 214a, actuator, 214b, actuator, 322, cleaning bin, 400, mobile cleaning robot, 402, body, 411, skid, 412, drive wheel, drive wheel arm, 454, suspension system, 456, drive wheel arm, 458 Cam, 460 Cam follower assembly, 462 Spring assembly, 464 Pivot, 466 Drive train, 468 Protrusion, 470 Slot, 472 Cam surface, 474 Cam arm, 476 Cam follower, 478 Pin, 480 Pivot, 482 Biasing element, 484 Extension tube, 486 Spring connection, 488 Pivot, 490 Tube post, 492 Stopper, 500 Robot, 502 Body, 512 Drive wheel, 554 Mobile cleaning robot suspension system, 556s Drive wheel arm, 558 Cam, 564 Pivot, 572 Cam surface, 574 Cam arm, 576 Cam follower, 578Pin, 580 Pivot, 582 Biasing element, 588 Pivot, 590 Tube post, 594 Wheel center, 600 Performance chart, 602 Downforce, theoretical plot, 604 Downforce, hysteresis plot, extension downforce, 606 Downforce, hysteresis plot, retraction downforce, 700 Performance chart, 702 Downforce, calculated force, 704 Downforce, 706 Downforce, D1 first wheel downforce, D2 second wheel downforce, L1 length, L2 length, M1 moment arm, M2 moment arm, S1 first spring force, S2 second spring force

Claims

1. 1. A mobile cleaning robot capable of moving within an environment, the mobile cleaning robot comprising: The main body, a drive wheel arm coupled to the body and movable relative to the body between an extended position and a retracted position; a drive wheel coupled to the drive wheel arm and movable with the drive wheel arm, the drive wheel operable to move the mobile cleaning robot; and a cam coupled to the drive wheel arm and movable with the drive wheel arm; a cam follower coupled to the body and engaged with the cam to move the drive wheel arm toward the extended position; A mobile cleaning robot.

2. a biasing member coupled to the body and the cam follower for biasing the drive wheel arm toward the extended position; The mobile cleaning robot of claim 1 further comprising:

3. a cam arm connecting the cam follower to the body, the biasing member being connected to the cam arm; The mobile cleaning robot according to claim 2.

4. 4. The mobile cleaning robot of claim 3, wherein the cam follower is rotatable relative to the cam arm to rotationally follow the cam.

5. an extension tube connected to the biasing member and to the cam arm for connecting the biasing member to the cam arm; The mobile cleaning robot of claim 4 , further comprising:

6. 6. The mobile cleaning robot of claim 5, wherein the biasing member and the extension tube extend beyond a connection point between the extension tube and the cam arm.

7. 6. The mobile cleaning robot of claim 5, wherein the drive wheel arm is pivotally connected to the body, the cam arm is pivotally connected to the body, and the biasing member is pivotally connected to the body.

8. 8. The mobile cleaning robot of claim 7, wherein the extension tube is pivotally connected to the cam arm.

9. 4. The mobile cleaning robot of claim 3, wherein the body includes a stopper engageable with the cam arm to limit application of a downward force to the drive wheel arm.

10. 10. The mobile cleaning robot of claim 1, wherein the cam is shaped to deliver a non-linear downforce from the drive wheel as the drive wheel moves between the extended position and the retracted position.

11. 10. The mobile cleaning robot of claim 1, wherein the cam is shaped to deliver a desired force profile over a range of movement of the drive wheel arm between the extended position and the retracted position.

12. 1. A suspension assembly for a mobile cleaning robot, comprising: a drive wheel operable to move the mobile cleaning robot; a drive wheel arm coupled to a body of the mobile cleaning robot and supporting the drive wheel, the drive wheel arm being movable between an extended position and a retracted position relative to the body; a cam coupled to the drive wheel arm and movable with the drive wheel arm; a cam follower coupled to the body and engaged with the cam to move the drive wheel arm toward the extended position; A suspension assembly comprising:

13. a biasing member coupled to the body and the cam follower for biasing the drive wheel arm toward the extended position; The suspension assembly of claim 12 further comprising:

14. a cam arm connecting the cam follower to the body, the biasing member being connected to the cam arm; 14. A suspension assembly according to claim 13.

15. an extension tube connected to the biasing member and to the cam arm for connecting the biasing member to the cam arm; The suspension assembly of claim 14 further comprising:

16. 16. The mobile cleaning robot of claim 15, wherein the biasing member has a length that is greater than a distance between a connection point of the biasing member to the body and a connection point of the extension tube to the cam arm.

17. 17. The suspension assembly of claim 16, wherein the drive wheel arm is pivotally connected to the body, the cam arm is pivotally connected to the body, and the biasing member is pivotally connected to the body.

18. 18. The suspension assembly of claim 17, wherein the extension tube is pivotally connected to the cam arm.

19. 1. A mobile cleaning robot capable of moving within an environment, the mobile cleaning robot comprising: The main body, a drive wheel operable to move the mobile cleaning robot; a drive wheel arm coupled to the body and supporting the drive wheel, the drive wheel arm being movable relative to the body between an extended position and a retracted position; a cam assembly coupled to the body and the drive wheel arm for delivering a desired force profile over a range of movement of the drive wheel arm between the extended position and the retracted position; A mobile cleaning robot.

20. a biasing member coupled to the body and the cam follower for biasing the drive wheel arm toward the extended position; 20. The mobile cleaning robot of claim 19, further comprising:

21. a cam arm connecting the cam follower to the body, the biasing member being connected to the cam arm; 21. The mobile cleaning robot of claim 20.

22. 22. The mobile cleaning robot of claim 21, wherein the cam follower is rotatable relative to the cam arm to rotationally follow the cam.

23. an extension tube connected to the biasing member and to the cam arm for connecting the biasing member to the cam arm; 23. The mobile cleaning robot of claim 22, further comprising:

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