Abstract:
A floor mopping assembly finding use in a cleaning robot. The cleaning robot may be remotely controlled or autonomous. In one embodiment, a feed roller lets out a roll of webbing or toweling, a take-up roller reels in the toweling, and a motor system causes transfer of the toweling between the feed roller and the take-up roller. A housing holds the motor system and the rollers, which are mounted in the housing such that the motor causes transfer of the webbing between the rollers. One of the rollers is configured to rest on the floor or surface so as to cause the toweling to clean the surface. In an alternative embodiment, the assembly also includes a pad to press the toweling against the surface, where the pad is mounted in the housing such that the motor causes transfer of the toweling between the rollers and between the pad and the surface.

Description:
RELATED APPLICATIONS 
     This application claims the benefit of the filing date of U.S. patent application Ser. No. 60/201,168, entitled “REMOTE CONTROLLED FLOOR MOPPING APPARATUS”, filed on May 2, 2000, which is hereby incorporated by reference. 
     This patent application is related to U.S. patent application Ser. No. 09/847,600 for “APPARATUS AND METHOD FOR IMPROVING TRACTION FOR A MOBILE ROBOT”, concurrently filed May 2, 2001, and which is hereby incorporated by reference. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     Aspects of the present invention relate to automated, robotic floor mopping. More specifically, embodiments of the present invention relate to a unique electric floor cleaning system that can be incorporated into a wide variety of robot or remote control platforms. 
     2. Description of the Related Technology 
     Robotic technology is under development in many academic and industrial environments. A great challenge for mobile robots is robust navigation, which has been solved in a variety of applications. Computer processing power, batteries, electronic sensors such as cameras, and efficient electric motors are all either just becoming available, cost effective or reliable enough to use in consumer robots. Industry has finally reached the point where commercial success of household robots has become an implementation issue, rather than a technology issue. 
     Mobile robots have been designed, developed and deployed to handle a variety of tasks, such as manufacturing and security. As robots become more prevalent in society, they will continue to automate tasks currently performed by people. Household cleaning and maintenance is an obvious application for robotics, and pool cleaning, lawn mowing and vacuuming robots have been developed. 
     Mopping is another obvious candidate for automation, but automated mopping is not as simple as making a robot that mops like a person. The methods humans use to perform household tasks have evolved over time based on the tools available, but a robot will not necessarily perform tasks in the same manner as a person. For example, people use their arms and legs to walk and work, while most robots use motors and wheels. 
     While it is possible to automate current manual or electric mopping devices and methods, the result would be a poorly performing machine based on a compromise of ideas. People clean surfaces, such as floors, using mops and buckets of water. A mopping robot would have to be large enough to hold both clean and dirty water reservoirs, and, therefore, could not clean small, hard-to-reach areas. The clean water and cleaning solution require refilling, the dirty water needs emptying, and the mop head needs to be cleaned and occasionally replaced. Water and drains would need to be plumbed to locations the robot could reach. Even if this was done in new construction, leaks in the robot or in the filling station would be potentially catastrophic. Designing failsafe machines to work with water is complicated and expensive. Therefore, a robot mop needs a unique and innovative cleaning apparatus to work effectively. 
     Most mopping is done manually with a mop and a bucket of water. The Swiffer™ is a product that uses small disposable towels to damp mop smooth floors. In addition to being a manual device, this product is inconvenient because it is does not deep clean and each individual towel only cleans a small area. Current electric mopping machines and waxers use spinning brushes, either flat disks that spin on an axis perpendicular to the ground or cylindrical brushes that spin on an axis parallel to the ground. 
     Another mopping approach uses a long damp towel on two rollers. The towel in this system is configured similar to a scroll such that it is wound on two rollers, feed and take-up reels, mounted on a handle. Typically, the feed reel is exposed, and the user presses it against the ground to mop. When the area of towel gets dirty, the user manually winds the towel further onto the take-up reel to expose a clean towel area. Trigger mechanisms that wind the towel with a press of a button have also been developed. A disposable cartridge/towel system has also been developed for this type of mopping approach. 
     A robot mopping system is appealing to consumers. However, all the heretofore proposed robot mops are simply automated versions of electric mopping devices. A variety of water and plumbing issues make the viability of such a system questionable. 
     SUMMARY OF THE INVENTION 
     Aspects of the present invention are directed toward a system and method of automated, robotic floor mopping. The unique electric cleaning system can be incorporated into a wide variety of robot or remote control platforms. One embodiment includes a fully automated robotic floor mopping machine that damp mops the floor using a pre-moistened roll of towels or webbing that automatically advances from a feed roll to a take-up roll. While this embodiment is directed to a self-contained robot mopping apparatus, another embodiment of the mopping system could also be incorporated in a slave platform that operates in conjunction with a controller robot. 
     Unlike all current electric and robot mopping devices that use spinning brushes and onboard water reservoirs, this system uses a pre-moistened web or towel on a roller system. The general cleaning process is similar to how a person works with a sponge. The robot moves back and forth while pressing the towel against the floor. Instead of rinsing the towel, the robot turns its rollers exposing a clean section of towel. For convenience, the towel can be delivered on a roll that is pre-moistened with a cleaning solution and is disposable. 
     While it is possible to use the take-up or feed reel as the cleaning head, such as in previous mechanical devices, one embodiment presses the towel against the floor by a pliable, sponge-like object. The dual benefits are increasing the size of cleaning area, and the soft pressure improves cleaning because the towel will contour to irregularities in the floor such as grout between tiles. 
     Typically, the roll of toweling is transferred between two reels at a controlled rate as the robot moves in a mopping motion across the floor. However, the robot can use optical or other sensors to determine when the exposed portion of the towel is dirty and advance the towel on the reels when appropriate. Research has shown that one square foot of toweling cleans approximately 25 square feet of flooring. The towel can be made of any cloth, paper or other appropriate material, but a tough, disposable paper-based material is preferable in one embodiment. Simple water can be used as the cleaning solution, but adding soap or other cleaner improves the mop efficacy. It is also feasible to use a dry towel and have the robot apply a cleaning solution. This necessitates a reservoir on the robot in one embodiment. 
     In one aspect of the present invention, there is a floor mopping assembly, comprising a first roller configured to let out a web mounted on a roll; a second roller configured to reel in the web; a motor system configured to cause transfer of the web between the first roller and the second roller; a pad configured to press the web against a surface; and a housing to enclose the motor system, the first roller, the second roller and the pad, wherein the motor system, the first and second rollers, and the pad are mounted in the housing such that the motor causes transfer of the web between the first and second rollers and between the pad and the surface. 
     In another aspect of the present invention, there is a floor mopping assembly, comprising a computerized mobile chassis, a first roller configured to let out a roll of webbing, a second roller configured to reel in the webbing, and a motor system configured to cause transfer of the webbing between the first roller and the second roller, wherein the motor system and the first and second rollers are conveyed by the chassis. 
     In another aspect of the present invention, there is a floor mopping assembly, comprising a computerized mobile chassis, a first means for letting out a portion of webbing, a second means for taking up the webbing, and a motor means for causing transfer of the webbing between the first means and the second means. 
     In yet another aspect of the present invention, there is a method of mopping a surface with a floor mopping device, the method comprising a) connecting a roll of webbing on a feed roller to a take-up roller, b) moving the floor mopping device without human intervention, c) pressing on a portion of the webbing such that the webbing cleans the surface, and d) transferring the portion of the webbing to the take-up roller. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front perspective diagram of a single robot embodiment of an automated floor-mopping device. 
     FIG. 2 is an exploded view diagram of exemplary components of the single robot, automated floor mopping device shown in FIG.  1 . 
     FIG. 3 is a sectional view diagram of the single robot, automated floor mopping device shown in FIG. 1 further showing the towel, feed and take-up rollers and the pliable cleaning head conforming to irregularities to the floor shape. 
     FIG. 4 a  and FIG. 4 b  are lower and upper perspective view diagrams, respectively, of an embodiment of a remotely controlled, automated floor-mopping device. 
     FIG. 5 is a front perspective diagram of an embodiment of a remote control, automated floor mopping device under the direction of an independent controller robot. 
     FIG. 6 is a sectional view diagram showing the feed roll as the cleaning head as may be used in the automated floor mopping device shown in FIGS. 1 and 4. 
     FIGS. 7 a  and  7   b  show a mechanism in schematic form that raises and lowers the towel mechanism as may be used in the automated floor mopping device shown in FIGS.  1  and  4 . 
    
    
     DETAILED DESCRIPTION 
     The following detailed description presents a description of certain specific embodiments of the present invention. However, the present invention may be embodied in a multitude of different ways as defined and covered by the claims. In this description, reference is made to the drawings wherein like parts are designated with like numerals throughout. 
     Aspects of the present invention are directed towards a system and robotic or remote control method for mopping a floor. In particular, the system overcomes the drawbacks of having a mopping device carry reservoirs of clean and dirty water as well as a detergent or other cleaning or waxing solutions. 
     FIG. 1 shows a front perspective of one embodiment of an autonomous robot mop  100 . The overall shape and configuration of the robot may affect its ability to autonomously clean and navigate an environment, but generally does not affect, nor is affected by, the automated floor-mopping aspects of this invention. 
     FIG. 2 is an exploded view of the robot mop  100  embodiment shown in FIG.  1 . Wires, hardware and other components have been removed in the view of FIG. 2 for simplification. In one embodiment, the robot is housed inside a plastic shell  101 , and controlled by a custom computer assembly  102  that includes a Central Processing Unit (CPU) or processor, Random Access Memory (RAM), and non-volatile storage. There are many CPUs that are sufficient for use including, for example, those manufactured by Intel, Motorola, and Microchip (PIC). The computer assembly  102  processes information received from sensors  103  to determine its position, the room types and so on, in order to determine what should be done next. Additionally, the computer assembly  102  controls all the motors on the robot in one embodiment. Information about the environment, such as a map and task schedule, is maintained in non-volatile memory. The computer assembly  102  includes two camera sensors  103  that view through lenses  104  to provide stereo vision. Wide angle lenses such as those found in some readily available Web and security cameras are preferred in this embodiment. While cameras are the sensors in one embodiment, the robot can also use ultrasonic, radar or lidar sensors in place of or in conjunction with the cameras. The cameras are the primary sensors facing the forward direction, and additional cameras or other sensors may optionally be oriented around the periphery of the robot. The robot may also use short range ultrasonic or touch sensors, floor type sensors or other additional ways to improve its performance. 
     A left drive wheel and drive motor assembly  107  and a right drive wheel and drive motor assembly  108  mounted on a bracket  109  within the shell propel the robot  100 . A battery  106  powers the system. Ideally, the battery  106  provides sufficient voltage for the computer, sensors and motors. Otherwise, the system may require one or more transformers. In one embodiment, a rechargeable battery is utilized and is sized to provide an hour or more of power for the robot to effectively clean between charges. NiCad, lithium ion, lead acid and other battery technologies may be successfully used. The mopping system is mounted on a bottom plastic shell  110 . It includes a pre-moistened web or towel  115  assembled onto a feed roll, reel or roller  116  and a take-up roll  117 . The entire towel assembly is configured in a manner similar to a scroll where the paper is wound from one roll onto the other roll. The ends of both rollers  116 ,  117  have details that snap into mating features  119  on the lower shell  110 . One end of the take-up roll has a gear  118  that meshes with a gear  112  mounted on a towel drive motor  111 . When the towel  115  is in place within the robot  100 , the cleaning area passes over a non-absorbent cushioning pad  114  adhered to a mounting plate  113 , which may be a solid mounting plate. One or more weights  105  may be added to the robot system to ensure that the towel  115  is pressed against the floor with an appropriate pressure. In one embodiment, closed cell foams are utilized for the pad because they are durable and do not absorb water. However, self-skinning open cell foams such as urethane and neoprene are acceptable as are other sponge type materials enclosed in a watertight bag. 
     As the robot  100  moves back and forth across the floor of an area or room, the towel  115  mops the floor. During use, the towel is transferred between the feed reel  116  and the take-up reel  117  at a controlled rate. Tests indicate that one square foot of towel can clean approximately 25 square feet of floor. The computer assembly  102  can advance the towel a specific amount based on the amount of floor that is cleaned. Alternatively, the robot  100  could include a sensor, such as a camera, to determine when the active cleaning area of the towel is dirty. One embodiment uses one motor  111  on the take-up reel  117  and assumes there is sufficient friction on the feed reel  116  to prevent it from inadvertently unwinding in use. Alternate embodiments can include drive motors on both rollers and/or clutches or friction brakes to ensure tension on the towel. 
     In one embodiment, the towel  115  is embodied in a disposable assembly that snaps into the robot and is removed when the entire length has been used. A paper-based towel similar to a paper towel or a handiwipe™ is used in one embodiment, but a cloth towel is an alternative. Alternatively, a non-disposable cloth towel could be removed and washed between uses. Regardless of the material, the towel is to be pre-moistened. Adding soap or other cleaning agent to the mixture improves the cleaning characteristics. Similarly, the towel could be pre-moistened with a wax so as to wax, rather than mop, a floor. 
     In many embodiments, a length of the towel on the roll is independent of the amount of towel needed to clean the floor. Therefore, the towel may remain on the robot mop for an indefinite period. For these embodiments, it may be preferable to encase the feed roll in a watertight compartment including a seal around where the towel exits the compartment. This will enable the towel to remain wet between uses. 
     Minimizing the robot size allows it to clean smaller spaces. However, the smaller the robot, the smaller the towel roll it can carry and the smaller the amount of floor it can clean before the towel needs replacing. An alternative is to provide a large roll of toweling and have the robot automatically load a length of towel as required. The robot can either load a standard length, or it could determine the amount it needs for a day and take that amount. In such an automated system, the robot disposes of the dirty towels. 
     As shown in FIG. 3, the use of the non-absorbent pad  121  (which is similar to the pad  114 ) offers several improvements to previous cleaning devices. It provides a relatively large cleaning surface and ensures constant pressure when the towel  122  (which is similar to towel  115 ) is pressed against a surface or floor  120 . The towel is transported from a feed roller  123  to a take-up roller  124  In one embodiment, the pad  121 , the towel  122 , the feed roller  123 , the take-up roller  124 , and drive wheels  125  (only one wheel is shown) are configured in a robot housing  126  as shown. In another embodiment, the position of the feed roller and the take-up roller may be interchanged. Since the pad is soft and compliant in one embodiment, it conforms to irregularities in the floor, such as grout lines  127  in tile flooring. This feature improves the cleaning ability of the robot mopping system. 
     FIG. 4 shows a top perspective view (FIG. 4 b ) and bottom perspective view (FIG. 4 a ) of a remotely controlled mopping device  130 . This device  130  includes a pre-moistened cleaning towel  131 , a non-absorbent cushioning pad  132  and a drive system  133  mounted in a plastic shell  134 . However, the mopping device  130  does not include the sensors and electronics to autonomously navigate through its environment. A person using a joystick or other similar controller could control this device in a manner similar to that done with toy cars. 
     Alternatively, the mopping device could be a slave robot in a master/slave system  142  such as shown in FIG.  5 . In this configuration, the mop  141  (which is similar to the mopping device  130 ) performs the cleaning under the control of the master robot  140 . The master robot  140  includes most or all of the electronics and sensors, and directs the slave&#39;s movement such as described in Applicant&#39;s copending U.S. patent application Ser. No. 09/449,177, filed on Nov. 24, 1999, entitled “Autonomous Multi-Platform Robot System”, which is hereby incorporated by reference. In this system  142 , a single control robot such as master robot  140  could work with multiple cleaning devices, such as sweepers and vacuums. It is possible for the master controller to be a stationary computer provided there are sufficient sensors for it to track the slave device throughout a house or other building. 
     Referring again to FIG. 4, a leading (or trailing) wheel  135  that is not on the same axis as the drive system  133  may be incorporated into the robot or remote device to improve the drive system. In such a three wheel system, or alternatively, in a four or more wheel system, the robot or remote device is balanced better than a two wheel system and the extra wheel(s) provides a limit as to how much the absorbent pad  132  can be compressed by the weight of the robot or device  130 . Therefore, such (wheels in more than one axis) configurations provide for the absorbent pad  132  to be compressed by a specific and constant amount. Alternatively, the foam pad  132  can be weighted or spring loaded to apply a specific and constant cleaning pressure to the towel that is less than the weight of the entire robot  130 . 
     As shown in FIG. 6, it is possible to remove the non-absorbent pad, such as pad  121  shown in FIG. 3, and have either the feed roll  150  or the take-up roll  151  directly contact the floor as in similar non-automated systems. The robot housing  152  and the entire robot system is designed to adjust for the change in size of the towel roll. In one embodiment, the housing adapts mechanically because the height of the contact area changes as the towel is transferred between rolls. Electronically, the feed rate also varies because the effective cleaning head changes size during use. 
     FIGS. 7 a  and  7   b  show an embodiment where a motor  162  and lead screw  161  raise the non-absorbent pad from a lowered position  160  (FIG. 7 a ) to a raised position  164  (FIG. 7 b ) when the device is not mopping. In this embodiment, the robot mop rides on a skid pad  163 , or a trailing wheel, when the pad is raised. This configuration enables the robot to traverse a floor, such as carpet, without mopping it. Raising the pad to position  164  also helps the robot move if it gets stuck or if the wheels slip. 
     In an alternate embodiment, the robot can automatically load the towel from a base station. The system can either change an entire towel cartridge, or can wind the towel from a large roll using a feed mechanism similar to a movie projector or printer. In this situation, the robot can calculate and the load the amount of towel required to mop the floor. 
     Conclusion 
     Specific blocks, sections, devices, functions and modules may have been set forth. However, a skilled technologist will realize that there are many ways to partition the system of the present invention, and that there are many parts, components, modules or functions that may be substituted for those listed above. 
     While the above detailed description has shown, described, and pointed out the fundamental novel features of the invention as applied to various embodiments, it will be understood that various omissions and substitutions and changes in the form and details of the system illustrated may be made by those skilled in the art, without departing from the intent of the invention.