Autonomous robot auto-docking and energy management systems and methods

A method for docking an autonomous mobile floor cleaning robot with a charging dock, the robot including a receiver coil and a structured light sensor, the charging dock including a docking bay and a transmitter coil, includes: positioning the robot in a prescribed docked position in the docking bay using the structured light sensor and by sensing a magnetic field emanating from the transmitter coil; and thereafter induction charging the robot using the receiver coil and the transmitter coil with the robot in the docked position.

FIELD

The present invention relates generally to robotic systems and, more specifically, to auto-docking and energy management systems for autonomous robots.

BACKGROUND

Automated robots and robotic devices are used to perform tasks traditionally considered mundane, time-consuming, or dangerous. As the programming technology increases, so too does the demand for robots that require a minimum of human interaction for tasks such as robot refueling, testing, and servicing. A goal is a robot that could be configured a single time, which would then operate autonomously, without need for human assistance or intervention.

SUMMARY OF THE INVENTION

According to embodiments of the invention, a method for docking an autonomous mobile floor cleaning robot with a charging dock, the robot including a receiver coil and a structured light sensor, the charging dock including a docking bay and a transmitter coil, includes: positioning the robot in a prescribed docked position in the docking bay using the structured light sensor and by sensing a magnetic field emanating from the transmitter coil; and thereafter induction charging the robot using the receiver coil and the transmitter coil with the robot in the docked position.

In some embodiments, the dock includes an upstanding backstop, and the method further includes aligning the mobile floor cleaning robot with the charging dock using the structured light sensor by detecting the backstop using the structured light sensor.

In some embodiments, when the robot is in the docked position, the receiver coil is located in a prescribed alignment with the transmitter coil.

In some embodiments, the method includes: executing a cleaning mission using the robot; and using the structured light sensor to detect obstacles and/or voids proximate the robot during the cleaning mission.

According to embodiments of the invention, an autonomous mobile floor cleaning robot for cleaning a surface includes a housing, a motive system, an induction charging system, and a cleaning system. The housing has a bottom. The motive system is operative to propel the robot across the surface. The induction charging system includes a receiver coil in the housing proximate the bottom of the housing, the receiver coil being configured to be inductively coupled to a transmitter coil in a charging dock during a charging operation. The cleaning system is operative to clean the surface as the robot traverses the surface. The cleaning system includes an evacuation port located in the bottom of the housing to release debris from the robot.

In some embodiments, the receiver coil is offset from the center of the robot.

According to embodiments of the invention, an autonomous mobile robot includes a housing, a motive system, and an induction charging system. The housing has a bottom. The motive system is operative to propel the robot across a surface. The induction charging system includes a receiver coil in the housing proximate the bottom of the housing. The housing includes a bottom wall separating the receiver coil from the surface.

In some embodiments, the robot further includes a cleaning system operative to clean the surface as the robot traverses the surface. In some embodiments, the receiver coil is sealed from the environment and the cleaning system by the housing.

In some embodiments, the robot further includes a cutting element suspended from the bottom of the housing.

In some embodiments, the housing defines a coil chamber configured to receive the receiver coil, the coil chamber positioned at the bottom of the housing, and the receiver coil is disposed in the coil chamber. In some embodiments, the receiver coil is substantially planar and the coil chamber holds the receiver coil horizontal above the surface. According to some embodiments, a nominal thickness of the portion of the bottom wall defining the coil chamber is at least 2 mm, and a nominal thickness of a top wall defining the coil chamber is at least 2 mm.

According to some embodiments, the housing includes a chassis and a bottom cover, the chassis includes a chassis bottom wall covering the receiver coil and separating the receiver coil from a compartment of the robot, and the bottom cover separates the receiver coil from the surface.

In some embodiments, a center axis of the receiver coil is horizontally offset from a lateral centerline extending between front and rear edges of the robot by an offset distance. According to some embodiments, the offset distance is in the range of from about 2 cm to 8 cm.

In some embodiments, the autonomous mobile robot further includes a debris bin disposed at least partially above the receiver coil.

According to some embodiments, the autonomous mobile robot further includes an evacuation port located in the bottom of the housing at a position horizontally offset from a lateral centerline extending between the front and rear edges of the robot and located adjacent the coil.

In some embodiments, the front of the robot defines a square profile.

In some embodiments, the receiver coil is located a vertical distance from a lower outer surface of the bottom wall in the range of from about 1 mm to 5 mm. According to some embodiments, the receiver coil is located a vertical distance from a lower outer surface of the bottom wall of less than about 3 mm.

According to some embodiments, windings of the receiver coil are mechanically fixed to an inside of a top surface of the bottom wall.

In some embodiments, the receiver coil is affixed to an inside top surface of the bottom wall by adhesive or fasteners.

According to some embodiments, the receiver coil is molded into the bottom wall or a top wall of the housing overlying the receiver coil.

In some embodiments, the receiver coil is encased by plastic on both its top and bottom sides.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

It will be understood that when an element is referred to as being “coupled” or “connected” to another element, it can be directly coupled or connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly coupled” or “directly connected” to another element, there are no intervening elements present. Like numbers refer to like elements throughout.

The term “monolithic” means an object that is a single, unitary piece formed or composed of a material without joints or seams.

With reference toFIGS. 1-14, an autonomous coverage robot system10according to some embodiments is shown therein. The system10includes a vacuum cleaning robot100and a base station or dock200. The system10may include an evacuation dock300(FIG. 13) in addition to or in place of the dock200. The robot100is adapted to mate with the dock200and the evacuation dock300.

The system10also includes a charging or energy management system205and an auto-docking control system201each including cooperatively operating components of the robot100and the dock200. In some embodiments, the energy management system205includes an air gap transformer or induction charging circuit (including a primary or transmitter coil244in the dock200and a secondary or receiver coil164in the robot100) to enable wireless charging of the robot100by the dock200.

In the following description of the autonomous robot100, use of the terminology “forward/fore” refers generally to the primary direction of motion of the robot100, and the terminology fore-aft axis (see reference characters “FA” inFIG. 4) defines the forward direction of motion F (FIG. 4), which is coincident with the fore-aft diameter of the robot100.

The robot100further defines a lateral or left-right axis LA and a vertical axis VA that are perpendicular to one another and to the axis FA. The axes FA and LA define a plane that is substantially parallel to the plane defined by the points of contact of the wheels132and caster134(described below) or the support surface (e.g., floor) on which the robot100rests.

The description also uses a frame of reference based on the dock200including X-, Y- and Z-axes, which are depicted inFIG. 8. The X-, Y- and Z-axes are perpendicular to one another and intersect at the center of the dock200. Movements, distances and dimensions along the Y-axis may be referred to as lateral, leftward or rightward. Movements, distances and dimensions along the X-axis may be referred to herein as depthwise, fore-aft, forward or rearward. Movements, distance and dimensions along the Z-axis may be referred to herein as vertical. The X- and Y-axes define a plane that is parallel to the support surface on which the dock200rests (e.g., a floor).

In the embodiment depicted, the robot100includes a robot controller102, a body, housing infrastructure or housing (hereinafter, “housing”)111, an electrical energy storage battery126, a motive system130, a cleaning system140, a detector system150, and an energy management or charging subsystem160. The detector system150forms a part of the auto-docking control system201.

The housing111has an undercarriage115(FIG. 3) and defines an internal main chamber118(FIG. 2). The undercarriage115forms the underside or bottom side of the housing111and the robot100. The housing111includes a chassis110, a top cover112, a bottom or undercarriage cover114, and a displaceable bumper116. The robot100may move in a forward direction F and a reverse drive direction R; consequently, the chassis110has corresponding forward and back ends,110A and110B, respectively.

The chassis110may be molded from a material such as plastic as a unitary or monolithic element that includes a plurality of preformed wells, recesses, and structural members for, inter alia, mounting or integrating elements of the various subsystems that operate the robot100. The covers112,114may be molded from a material such as a polymeric material (plastic) as respective unitary or monolithic elements that are complementary in configuration with the chassis110and provide protection of and access to elements and components mounted to the chassis110. The chassis110and the covers112,114are detachably integrated in combination by any suitable means (e.g., screws). In some embodiments and as shown, the housing111has a front end defining a square profile. In some embodiments, the chassis110and covers112,114form a structural envelope of minimal height having a generally D-shaped configuration that is generally symmetrical along the fore-aft axis FA.

An evacuation port120is defined in the undercarriage cover114and the bottom wall110C of the chassis110. The evacuation port120may be provided with a closure device or flap120A (FIG. 5).

A coil chamber124is defined between the undercarriage cover114and the bottom wall110C of the chassis110(FIGS. 3 and 6). The undercarriage cover114forms a bottom wall of the coil chamber124, and the bottom wall110C forms a top wall of the coil chamber124.

The displaceable bumper116has a shape generally conforming to that of the front end of the chassis110and is mounted in movable combination at the forward portion of the chassis110to extend outwardly therefrom (the “normal operating position”). The mounting configuration of the displaceable bumper116is such that it is displaced towards the chassis110(from the normal operating position) whenever the bumper116encounters a stationary object or obstacle of predetermined mass (the “displaced position”), and returns to the normal operating position when contact with the stationary object or obstacle is terminated (due to operation of a control sequence which, in response to any such displacement of the bumper116, implements a “bounce” mode that causes the robot100to evade the stationary object or obstacle and continue its task routine).

Installed along either lateral side of the chassis110are independent drive wheels132that mobilize the robot100and provide two points of contact with the floor surface. The drive wheels132may be spring loaded. The rear end110B of the chassis110includes a non-driven, multi-directional caster wheel134that provides additional support for the robot100as a third point of contact with the floor surface. One or more electric drive motors136are disposed in the housing111and operative to independently drive the wheels132. The motive components may include any combination of motors, wheels, drive shafts, or tracks as desired, based on cost or intended application of the robot100.

In some embodiments, the cleaning system140includes a suction slot or opening142A defined in the undercarriage115. One or more motor driven rotating extractors (e.g., brushes or rollers)144flank the opening142A. An electric vacuum fan146pulls air up through a gap between the extractors144to provide a suction force that assists the extractors in extracting debris from the floor surface. Air and debris that pass through the gap are routed through a plenum142B that leads to an opening of a cleaning or debris bin145disposed or encased in the chamber118. The opening leads to a debris collection cavity145A of the debris bin145. A filter147located above the cavity screens the debris from an air passage leading to the air intake of the vacuum fan146. Filtered air exhausted from the vacuum fan146is directed through an exhaust port122.

A side brush148is mounted along the sidewall of the chassis110proximate the forward end110A and ahead of the extractors144in the forward drive direction F. The side brush148rotatable about an axis perpendicular to the floor surface. The side brush148allows the robot100to produce a wider coverage area for cleaning along the floor surface. In particular, the side brush148may flick debris from outside the area footprint of the robot100into the path of the centrally located cleaning head assembly.

Other suitable configurations for the vacuum cleaning system are disclosed in U.S. Pat. No. 9,215,957 to Cohen et al., U.S. Publication No. 2016/0166126 to Morin et al., and U.S. Pat. No. 8,881,339 to Gilbert, Jr. et al. the disclosures of which are incorporated herein by reference.

The robot controller circuit102(depicted schematically) is carried by the chassis110. The robot controller102is configured (e.g., appropriately designed and programmed) to govern over various other components of the robot100(e.g., the extractors144, the side brush148, and/or the drive wheels132). As one example, the robot controller102may provide commands to operate the drive wheels132in unison to maneuver the robot100forward or backward. As another example, the robot controller102may issue a command to operate one drive wheel132in a forward direction and the other drive wheel132in a rearward direction to execute a clock-wise turn. Similarly, the robot controller102may provide commands to initiate or cease operation of the rotating extractors144or the side brush148. In some embodiments, the robot controller102is designed to implement a suitable behavior-based-robotics scheme to issue commands that cause the robot100to navigate and clean a floor surface in an autonomous fashion. The robot controller102, as well as other components of the robot100, may be powered by the battery126disposed on the chassis110.

The detector system150(FIG. 4) includes a top or communications/guidance signal receiver or detector152, proximity or wall following sensors153, cliff sensors154, a forward directional receiver or detector156, an optical mouse sensor157, a magnetic field sensor155, an image sensing device158, and a camera159. In some embodiments, each of these sensors or detectors is communicatively coupled to the robot controller102. The robot controller102implements the behavior-based-robotics scheme based on feedback received from the plurality of sensors distributed about the robot100and communicatively coupled to the robot controller102.

The proximity sensors153(depicted schematically) are installed along the periphery of the robot100proximate the front corners of the robot100. The proximity sensors153are responsive to the presence of potential obstacles that may appear in front of or beside the robot100as the robot100moves in the forward drive direction F.

The cliff sensors154are installed along the forward end110A of the chassis110. The cliff sensors154are designed to detect a potential cliff, or flooring drop, forward of the robot100as the robot100moves in the forward drive direction F. More specifically, the cliff sensors154are responsive to sudden changes in floor characteristics indicative of an edge or cliff of the floor surface (e.g., an edge of a stair).

The communications/guidance signal detector152is mounted on the top front of the housing111of the robot100. The detector152is operable to receive signals projected from an emitter (e.g., the avoidance signal emitter232and/or the homing and alignment emitters234R,234L of the dock200) and (optionally) an emitter of a navigation or virtual wall beacon. In some embodiments, the robot controller102may cause the robot100to navigate to and dock with the dock200in response to the communications detector152receiving a home signal emitted by the dock200.

In some embodiments and as shown, the detector152is mounted at the highest point on the robot100and toward the front of the robot100as defined by the primary traveling direction, as indicated by an arrow on axis FA. In alternative embodiments, multiple detectors can be used in place of the top signal detector152. Such an embodiment might include using multiple side-mounted sensors or detectors. Each of the sensors can be oriented in a manner so that a collective field of view of all the sensors corresponds to that of the single, top mounted sensor. Because a single, omni-directional detector is mounted at the highest point of the robot for optimal performance, it is possible to lower the profile of the robot by incorporating multiple, side mounted detectors.

The forward directional detector156is mounted on the front end of the robot100and may be mounted on or behind the bumper116. The forward directional detector156receives signals projected from the emitters234R,234L on the dock200. In other embodiments, a pair of detectors receive signals from the emitters234R,234L or more than two detectors may be used.

In some embodiments, the detectors154,156are infrared (“IR”) sensor or detector modules, that include a photodiode and related amplification and detection circuitry, in conjunction with an omni-directional lens, where omni-directional refers to a substantially single plane. Any detector, regardless of modulation or peak detection wavelength, can be used as long as the emitters232,234R,234L on the base dock200are adapted to match the detectors152,156on the robot100. In another embodiment, IR phototransistors may be used with or without electronic amplification elements and may be connected directly to the analog inputs of a microprocessor. Signal processing may then be used to measure the intensity of IR light at the robot100, which provides an estimate of the distance between the robot100and the source of IR light.

As discussed hereinbelow, in some embodiments, a magnetic field sensing detector155is used in place of or in addition to the communications signal detector152and/or the directional detector156.

The camera159is a vision based sensor, such as a camera, having a field of view optical axis oriented in the forward drive direction of the robot100. In the illustrated embodiment, the camera159is located at the rear end110A of the robot with its line of sight angled forwardly and upwardly over the detector152. In some embodiments, the camera159is a video camera. In some embodiments, the camera159is used for detecting features and landmarks in the operating environment and building a map using Video Simultaneous Localization and Mapping (VSLAM) technology.

The optical mouse sensor157is located on the undercarriage115of the robot100. The circle shown in the top view ofFIG. 4shows relative placement of the optical mouse sensor157; however, the sensor157would not be visible in this view. The mouse sensor157tracks flooring and assists with drift compensation to keep the robot100moving in straight ranks.

The image sensing device158(FIG. 7) is mounted on the front end110A of the robot100. In some embodiments, the image sensor device158is mounted in or behind the bumper116and is protected by a transparent window116A. In some embodiments, the image sensing device158is a structured light sensor.

The image sensing device158includes a processor158A, a first light source158L, a second light source158U, and an image sensor158D, all of which may be integrated into a unitary module158E. The image sensor158D may be a CCD image sensor, an active pixel sensor, a CMOS image sensor or other suitable image sensor or camera. The light sources158L,158U may each be an LED, laser diode, or other suitable light source.

In use, the light sources158U,158L project light onto respective target or working surfaces WSL, WSU (FIG. 11), which light is reflected from the working surfaces onto the image sensor158D. The image sensor158D acquires a plurality or series of image frames. The image frames are processed by the processor158A to determine or calculate a depth, distance and/or displacement of the image sensor device158from or relative to each working surface WSL, WSU.

In some embodiments and as shown, the light source158L is configured to project its structured light beam BL (FIG. 11) at a downward oblique angle (relative to horizontal) to intersect a lower working surface WSL, and the light source158U is configured to project its structured light beam BU at an upward oblique angle (relative to horizontal) to intersect an upper working surface WSU. In operation, the lower surface WSL will typically be a floor or other support surface along which the robot100traverses, and the upper surface WSU may be objects in the environment of the robot100located above the floor or other support surface. In some embodiments, the image sensing device158determines the distance to each work surface based on the vertical location on the image sensor158D at which the beam BU or BL reflected off the working surface intersects the image sensor158D in the detection window of the image sensor158D.

Suitable structured light image sensing devices for use as the image sensing device158may include the Global Shutter Image Sensor available from PixArt Imaging, Inc. of Taiwan.

Various other types of sensors, though not shown in the illustrated examples, may also be incorporated in the robot100without departing from the scope of the present disclosure. For example, a tactile sensor responsive to a collision of the bumper116and/or a brush-motor sensor responsive to motor current of the brush motor may be incorporated in the robot100.

The robot100may further include a bin detection system for sensing an amount of debris present in the cleaning bin122(e.g., as described in U.S. Patent Publication 2012/0291809, the entirety of which is hereby incorporated by reference).

The robot charging subsystem160includes a charging circuit162that includes a secondary or receiver coil164. The robot charging subsystem160forms a part of the energy management system205.

In some embodiments, the receiver coil164includes a wire164A that is concentrically, spirally wound to form radially superimposed segments or turns164B, and input and output ends164C. In some embodiments, the coil164is substantially planar or flat.

According to some embodiments, the coil164has a thickness T1(FIG. 6) of less than 1.25 mm and, in some embodiments, in the range of from about 0.2 mm to 1.5 mm.

The receiver coil164is mounted in the undercarriage115of the robot100, under the bin145. As shown inFIG. 6, the receiver coil164is contained or encased in the coil chamber124. In some embodiments, the coil164is secured to the housing111in the coil chamber124. In some embodiments, the windings of the coil are mechanically fixed to the inside (top) surface of the cover114. The coil164may be affixed to the cover114and/or the bottom wall110C of the chassis110by adhesive or fasteners, for example. In some embodiments, the coil164is molded into the cover114and/or the bottom wall110C. In some embodiments, the coil164is molded in plastic so that it is encased by plastic (e.g., the cover114) on both its top and bottom sides (i.e., fully encased).

In some embodiments, the coil chamber124is closed or sealed off from the environment exterior of the robot100and from the main chamber118. In some embodiments, the coil chamber124is substantially hermetically sealed off from the environment exterior of the robot100and from the main chamber118. In this way, the coil164is isolated from the environment and the remainder of the robot100. The coil164is thereby protected from contamination by dust or debris around the robot or present within the robot100.

The receiver coil164is located in the undercarriage115at a location corresponding to the location of the transmitter coil244of the dock200. Generally, the receiver coil164on the robot100mirrors the transmitter coil244on the dock200. According to some embodiments and as shown inFIG. 5, the center axis RCA of the coil164is horizontally offset from the lateral centerline FA of the robot100in order to provide room for the evacuation port120. In some embodiments, the offset distance E1(FIG. 5) between the axes RCA and FA (i.e., the fore-aft midline of the robot100) is in the range of from about 2 cm to 8 cm.

In some embodiments, at least a portion of the debris bin is disposed above the receiver coil164. By locating the coil164at a location horizontally offset from the lateral centerline FA, room is provided on the undercarriage of the robot100to locate the evacuation port120laterally outside the outer diameter of the receiver coil164. As a result, the conduit or flow path from the debris bin145to the evacuation port120is located outside of the receiver coil164and not through the opening of the receiver coil164or through the coil chamber124.

In some embodiments, the coil164is oriented substantially parallel to the FA-LA plane of the robot100.

According to some embodiments, the receiver coil164is located a vertical distance E2(FIG. 6) from the lower outer surface of the bottom cover114of less than about 3 mm and, in some embodiments, in the range of from about 1 mm to 5 mm.

According to some embodiments, the nominal thickness T2(FIG. 6) of the portion of the bottom cover114defining the coil chamber124is at least 2 mm. According to some embodiments, the nominal thickness T3(FIG. 6) of the portion of the chassis bottom wall110C defining the coil chamber124(i.e., the top wall defining the coil chamber124) is at least 2 mm.

Further details of embodiments of the receiver coil164and the robot charging subsystem160are provided hereinbelow.

The robot100may be modified to perform any suitable task(s). For example, the robot100may be used for floor waxing and polishing, floor scrubbing, ice resurfacing (as typically performed by equipment manufactured under the brand name Zamboni®), sweeping and vacuuming, unfinished floor sanding and stain/paint application, ice melting and snow removal, grass cutting, etc. In some embodiments, the robot is configured as a mobility base carrying a retractable mast on which a camera is mounted. Any number of components may be required for such tasks, and may each be incorporated into the robot100, as necessary. For simplicity, this application will describe vacuuming as the demonstrative predetermined task. The energy management and auto-docking functions disclosed herein have wide application across a variety of robotic systems.

FIG. 8is a schematic perspective view a dock200in accordance with one embodiment of the invention. The dock200includes a housing211including both a substantially horizontal base plate or platform210and a substantially vertical tower or backstop220. A docking bay DB is defined over the platform210and in front of the backstop220. The dock200may be any of a variety of shapes or sizes, providing sufficient space for the desired components and systems, described below.

The platform210includes a coil chamber216(FIG. 9) defined therein. A raised pad wall212overlies the coil chamber216. Tracks214are defined on either lateral side of the coil chamber216and pad wall212.

The platform210is generally parallel to the ground surface on which the dock200rests or may be slightly ramped to provide space for wiring. The height or thickness of the platform210can be sized to accommodate a transmitter induction coil244.

The dock200includes a dock charging subsystem240, a communications/guidance system230, a dock controller222, and a power input connector224(connected to a power supply, not shown). The dock charging system240forms a part of the energy management system205.

The dock controller circuit222(depicted schematically) is carried by the housing211. The dock controller222is configured (e.g., appropriately designed and programmed) to govern over various other components of the dock200.

The communications/guidance system230(FIG. 8) includes a top signal emitter232, a first or right front homing/alignment emitter234R, a second or left front homing/alignment emitter234L, and a pair of horizontally spaced apart fine alignment emitters238.

The top signal emitter232is mounted on the top of the backstop220. The emitter232generates a first signal, such as an avoidance signal BA (FIG. 8), in a diffuse region near the dock200to prevent the robot from coming into inadvertent direct contact with the dock200while performing a task, such as vacuuming. The top signal emitter232may utilize a parabolic reflector to transmit the avoidance signal. In such an embodiment, the avoidance signal is emitted by a single LED directed at a lens whose geometry is determined by rotating a parabola about its focus. This parabolic reflector thus projects the avoidance signal BA out in a 360° pattern, without the necessity of multiple emitters. A similar configuration can be employed in the detector156on the robot, with a single receiver used in place of the single LED.

The homing/alignment emitters234R,234L are located on a front wall220A of the backstop220. In some embodiments, the emitters234R,234L are separated by a baffle236. The homing/alignment emitters234R and234L emit or project respective homing signals BR and BQ (FIG. 10) as discussed below. In some embodiments, the emitters234R,234L are LEDs. The emitters234R,234L serve as navigational buoys or fiducials. In some embodiments and as shown, the emitters234R,234L are laterally offset from the centerline X-X of the dock200and the directional detector156B is offset from the centerline FA of the robot100so that the detector156B is substantially centered between the emitters234R,234L when the robot100is in the docked position.

The fine alignment emitters238are located on the front wall220A. The fine alignment emitters238are spaced apart a prescribed distance E3(FIG. 8). In some embodiments, the distance E3is in the range of from about 1 cm to 3 cm. The fine alignment emitters238emit or project respective near alignment signals BN as discussed below. In some embodiments, the fine alignment emitters238are LEDs. The emitters238serve as navigational beacons or fiducials.

The dock charging subsystem240includes a charging circuit242, which includes a primary or transmitter coil244.

In some embodiments, the transmitter coil244includes a wire244A that is concentrically, spirally wound to form radially superimposed segments or turns244B, and input and output ends244C. In some embodiments, the coil244is substantially planar or flat.

According to some embodiments, the coil244has a thickness T4(FIG. 9) of less than 1.25 mm and, in some embodiments, in the range of from about 0.2 mm to 1.5 mm.

The transmitter coil244is mounted in the platform210of the dock200. In some embodiments and as shown inFIG. 9, the transmitter coil244is contained in the coil chamber216. In some embodiments, the coil244is secured to the platform210in the coil chamber216. The coil244may be affixed to the pad wall212and/or a bottom wall210A of the platform210by adhesive or fasteners, for example. In some embodiments, the coil244is molded into the pad wall212and/or the bottom wall217.

In some embodiments, the coil chamber216is closed or sealed off from the environment exterior of the dock200. In some embodiments, the coil chamber216is substantially hermetically sealed off from the environment exterior of the dock200. In this way, the coil244is isolated from the environment and protected from contamination by the robot100.

The transmitter coil244is located in the platform210in a location corresponding to the location of the receiver coil164of the robot100.

In some embodiments, the coil244is oriented substantially parallel to the floor.

According to some embodiments, the transmitter coil244is located a vertical distance E5(FIG. 9) from the upper outer surface of the pad wall212of less than about 7 mm and, in some embodiments, in the range of from about 3 mm to 20 mm.

According to some embodiments, the nominal thickness T5(FIG. 9) of the portion of the pad wall212defining the coil chamber216is at least 2 mm.

Further details of embodiments of the transmitter coil244and the dock charging subsystem240are provided hereinbelow.

The robot100uses a variety of behavioral modes to effectively vacuum a working area. Behavioral modes are layers of control systems that can be operated in parallel. The robot controller102(e.g., microprocessor) is operative to execute a prioritized arbitration scheme to identify and implement one or more dominant behavioral modes for any given scenario, based upon inputs from the sensor system. The robot controller102is also operative to coordinate avoidance, homing, and docking maneuvers with the dock200.

Generally, the behavioral modes for the described robot100can be characterized as: (1) coverage behavioral modes; (2) escape behavioral modes, and (3) safety behavioral modes. Coverage behavioral modes are primarily designed to allow the robot100to perform its operations in an efficient and effective manner, while the escape and safety behavioral modes are priority behavioral modes implemented when a signal from the sensor system indicates that normal operation of the robot100is impaired (e.g., obstacle encountered), or is likely to be impaired (e.g., drop-off detected).

Representative and illustrative coverage behavioral modes (for vacuuming) for the robot100include: (1) a Spot Coverage pattern; (2) an Obstacle-Following (or Edge-Cleaning) Coverage pattern, and (3) a Room Coverage pattern. The Spot Coverage pattern causes the robot100to clean a limited area within the defined working area, e.g., a high-traffic area. In a certain embodiments the Spot Coverage pattern is implemented by means of a spiral algorithm (but other types of self-bounded area algorithms, such as polygonal, can be used). The spiral algorithm, which causes outward or inward spiraling movement of the robot100, is implemented by control signals from the microprocessor to the motive system to change the turn radius/radii thereof as a function of time or distance traveled (thereby increasing/decreasing the spiral movement pattern of the robot100).

The foregoing description of typical behavioral modes for the robot100are intended to be representative of the types of operating modes that can be implemented by the robot100. One skilled in the art will appreciate that the behavioral modes described above can be implemented in other combinations and other modes can be defined to achieve a desired result in a particular application.

A navigational control system may be used advantageously in combination with the robot100to enhance the cleaning efficiency thereof, by adding a deterministic component (in the form of a control signal that controls the movement of the robot100) to the motion algorithms, including random motion, autonomously implemented by the robot100. The navigational control system operates under the direction of a navigation control algorithm. The navigation control algorithm includes a definition of a predetermined triggering event.

Broadly described, the navigational control system, under the direction of the navigation control algorithm, monitors the movement activity of the robot100. In one embodiment, the monitored movement activity is defined in terms of the “position history” of the robot100, as described in further detail below. In another embodiment, the monitored movement activity is defined in terms of the “instantaneous position” of the robot100.

The predetermined triggering event is a specific occurrence or condition in the movement activity of the robot100. Upon the realization of the predetermined triggering event, the navigational control system operates to generate and communicate a control signal to the robot100. In response to the control signal, the robot100operates to implement or execute a conduct prescribed by the control signal, i.e., the prescribed conduct. This prescribed conduct represents a deterministic component of the movement activity of the robot100.

The image sensing device158can be used to acquire information for guidance and operation of the robot during various operations of the robot100. In some embodiments, the image sensing device158is used to detect obstacles and hazards about the robot100so that those obstacles and hazards can be avoided or otherwise addressed. Within the operational range of the image sensor device158, the downwardly directed beam BL can be used to detect obstacles at or near the floor level as well as cliffs or depressions in the floor. The upwardly directed beam BU can be used to detect obstacles at or above the top of the robot100in order to detect and avoid obstacles under which the robot may become wedged.

In some embodiments, the image sensing device158is operative to effectively detect objects and voids up to at least 10 inches forward of the robot100and, in some embodiments, up to at least 12 inches.

The camera159can be used to navigate the robot and acquire images for other operational use. In some embodiments, the camera159is a VSLAM camera and is used to detect features and landmarks in the operating environment and build a map.

While the robot100is vacuuming, it will periodically approach the stationary dock100. Contact with the dock200could damage or move the dock100into an area that would make docking impossible. Therefore, avoidance functionality is desirable. To avoid inadvertent contact, the dock200may generate an avoidance signal BA, as depicted inFIG. 10. The avoidance signal BA is shown being transmitted from the emitter232on the top of the backstop220. The radial range of the avoidance signal BA from the dock200may vary, depending on predefined factory settings, user settings, or other considerations. At a minimum, the avoidance signal BA need only project a distance sufficient to protect the dock200from unintentional contact with the robot100. The avoidance signal BA range can extend from beyond the periphery of the dock200, to up to and beyond several feet from the dock200, depending on the application.

The avoidance signal BA may be an omni-directional (i.e., single plane) infrared beam, although other signals are contemplated, such as a plurality of single stationary beams or signals. If stationary beams are used, however, a sufficient number could provide adequate coverage around the dock200to increase the chances of the robot100encountering them. When the detector152of the robot100receives the avoidance signal BA from the emitter232, the robot100can alter its course, as required, to avoid the dock200. Alternatively, if the robot100is actively or passively seeking the dock200(for recharging or other docking purposes), it can alter its course toward the dock200, such as by circling the dock200, in such a way to increase the chances of encountering the homing signals as described below.

Generally, the avoidance signal BA is modulated and coded, as are the homing signals BR, BQ. The bit encoding method as well as binary codes are selected such that the robot100can detect the presence of each signal, even if the robot100receives multiple codes simultaneously.

Whenever measurable level of IR radiation from the avoidance signal BA strikes the detector152, the robot's IR avoidance behavior is triggered. In one embodiment, this behavior causes the robot100to spin in place to the left until the IR signal falls below detectable levels. The robot100then resumes its previous motion. In one embodiment, the detector152acts as a gradient detector. When the robot100encounters a region of higher IR intensity, the robot100spins in place. Because the detector152is mounted at the front of the robot100and because the robot100does not move backward, the detector152always “sees” the increasing IR intensity before other parts of the robot100. Thus, spinning in place causes the detector152to move to a region of decreased intensity. When the robot100next moves forward, it necessarily moves to a region of decreased IR intensity—away from the avoidance signal BA.

In other embodiments, the dock200includes multiple coded emitters at different power levels or emitters that vary their power level using a system of time multiplexing. These create concentric coded signal rings which enable the robot100to navigate towards the dock200from far away in the room. Thus, the robot100would be aware of the presence of the dock200at all times, facilitating locating the dock200, docking, determining how much of the room has been cleaned, etc. Alternatively, the robot100uses its motion through the IR field to measure a gradient of IR energy. When the sign of the gradient is negative (i.e., the detected energy is decreasing with motion), the robot100goes straight (away from the IR source). When the sign of the gradient is positive (energy increasing), the robot100turns. The net effect is to implement a “gradient descent algorithm,” with the robot100escaping from the source of the avoidance signal BA. This gradient method may also be used to seek the source of emitted signals. The concentric rings at varying power levels facilitate this possibility even without a means for determination of the raw signal strength.

In some embodiments, in order to dock, the system10executes a docking procedure including the following sequential steps: a) a seeking or discovery step; b) a homing or far approach step; and c) a near approach step. In some embodiments, the system10may also execute a fine approach step. The robot100may adopt corresponding modes in which it executes each of these steps (i.e., a seeking mode, a far approach mode, a near approach mode, and a fine approach mode). The docking procedure terminates with the robot100in a final, prescribed docked position DP (FIG. 1) within the docking bay DB. The docked position DP may include permitted tolerances or deviation from a precise target docked position.

In the seeking step, the robot100in the seeking mode seeks and discovers the presence and general location of the dock200with respect to the robot100.

Then, in the far approach step, the robot100in the far approach mode coarse or gross aligns with the docking bay DB of the dock200and progressively moves toward the docked position DP. The robot100may progress toward the dock200through an intermediate distance, after which the near approach step and mode take over.

Then, in the near approach step, the robot100in the near approach mode more closely aligns with the docking bay DB and further progressively moves toward the docked position DP. In this step, the robot100reduces the distance between the front end110A of the robot100and the front wall220A of the backstop220. The robot100may also adjust its lateral alignment or rotational orientation with respect to the platform210. In some embodiments, the robot100may turn and drive rearwardly into the docking bay DB (i.e., dock backwards).

Then, in the fine approach step, the robot100in the fine approach mode further progressively moves toward the target docked position and may terminate the approach upon reaching the docked position DP. In this step, the robot100fine tunes the distance between the front end110A of the robot100and the front wall220A of the backstop220. The robot100may also fine tune its lateral alignment or rotational orientation with respect to the platform210.

In some embodiments, the robot100performs its docking with the dock200accurately and repeatably, without the need for gross mechanical guidance features.

The robot100may assume its seeking mode and seek the dock200when it detects the need to recharge its battery, or when it has completed vacuuming the room. As described above, once the robot100detects or discovers the presence of the avoidance signal BA (and therefore the dock200), which in this mode serves as a discovery signal, it can assume the far approach mode and move as required to detect the homing signals BR, BL.

In the far approach step, the robot100uses the homing signals BR, BQ (FIG. 10) and its directional detector156to guide the robot100. As with the avoidance signal BA above, the projected range and orientation of the homing signals BR, BQ may be varied, as desired. It should be noted however, that longer signals can increase the chance of the robot100finding the dock200efficiently. Longer signals can also be useful if the robot100is deployed in a particularly large room, where locating the dock200randomly could be inordinately time consuming. Homing signal BR, BQ ranges that extend from approximately six inches beyond the front of the platform210, to up to and beyond several feet beyond the platform210are contemplated, depending on application. The angular width of the homing signals BR, BQ may vary depending on application, but angular widths in the range of 5° to up to and beyond 60° are contemplated. The angular width of each homing signal BR, BQ may be the area covered by the beam or sweep of the homing signal BR, BQ and, in some embodiments, is generally or substantially frusto-conical. A gradient behavior as described above can also be used to aid the robot in seeking out the dock200.

The two homing signals BR, BQ are distinguishable by the robot100, for example as a first or lateral right homing signal BR and a second or lateral left homing signal BQ. IR beams are generally used to produce the signals and, as such, are not visible. The IR beams may be modulated. Any signal bit pattern may be used, provided the robot100recognizes which signal to orient to a particular side. Alternatively, the signals BR, BQ may be distinguished by using different wavelengths or by using different carrier frequencies (e.g., 380 kHz versus 38 kHz, etc.).

Thus, when the robot100wants or needs to dock, if the detector156receives the right signal BR transmitting from the dock200, it moves to keep the right signal BR on the robot's right side; if it detects the left signal BQ transmitting from the dock200, it moves to keep the left signal BQ on the robot's left side. Where the two signals overlap (the overlap zone BO), the robot100knows that the dock200is nearby and may then dock. Such a system may be optimized to make the overlap zone BO as thin as practicably possible, to ensure proper orientation and approach of the robot100and successful docking. Alternatively, the right signal BR and left signal BQ may be replaced by a single signal, which the robot100would follow until docked.

FIG. 10depicts an exemplary path RP the robot100may traverse during a docking procedure utilizing the homing signals. When the detector156is in the left signal156field, the robot100will move towards the right, in direction MR in an effort to keep that left signal BQ to the left of the robot100. When the detector156is in the right signal BR field, thus the robot100will move towards the left, in direction ML in an effort to keep that right signal BR to the right of the detector156. Last, when the detector156encounters the overlap zone BO, the robot100will move in direction MD directly towards the dock100.

While approaching the dock200, the robot100may slow its speed of approach and/or discontinue vacuuming, or perform other functions to ensure trouble-free docking. These operations may occur when the robot100detects the avoidance signal BA, thus recognizing that it is close to the dock200, or at some other predetermined time, e.g., upon a change in the signal from the emitters234R,234L.

With reference toFIG. 11, in the near approach mode, the robot100uses the image sensor device158to guide the robot100in the near approach step. Data from the image sensor device158can be used to guide both lateral alignment of the robot100with respect to the backstop220and depth alignment (i.e., proximity) of the robot100with respect to the backstop200(i.e., the image sensor device158operates as a depth or distance detector). The image sensor device158uses the structured light beams BL, BU to detect the presence and relative location of the dock200relative to the front end110A of the robot100. In some embodiments, the image sensor device158detects the location of the backstop front wall220A as the robot100enters the docking bay DB.

The image sensor device158can thus gauge the distance between the front end110A of the robot100and the backstop220and thereby the position of the robot100relative to the dock200on the X-axis. The robot controller102can then use this information to control movement of the robot100.

In some embodiments, the near approach mode is assumed before the wheels132engage the tracks214. In some embodiments, the near approach mode is assumed when the robot100is in the range of from about 8 to 16 inches from the backstop220.

In some embodiments, the robot controller102will use the image sensor device158alone to determine the final position of the robot100. However, the desired docked position DP may be such that the spacing E7(FIG. 2) between the front wall220A and the image sensor158D is less than the specified or effective minimum range E8(FIG. 11) of the image sensor device158(i.e., the image sensor device158is too close to the front wall220A to accurately determine the distance). For example, the minimum range E8of the image sensor device158may be 3 cm and the spacing E7may be less than 5 mm. For this reason, the robot100may further execute a fine approach step. The fine approach step may be accomplished using different techniques/devices, as discussed below.

In some embodiments, in the fine approach step, the robot100uses the image sensor device158and the fine alignment emitters238to guide the robot100into its final docked position. The emitters238are spaced apart a known distance E3from one another. The modulated signal beams BN (FIG. 11) emitted from the emitters238are received directly at the image sensor158B. As the robot100approaches the backstop wall220A, the perceived distance between the emitters238shrinks, and when the perceived distance equals an expected value for the desired spacing E7of the robot100to the backstop wall220A, the robot100halts. From this, the image sensor device158can determine the distance to the backstop wall220A with sufficient accuracy within a range less than the effective minimum range of the image sensor device158(using structural light sensing).

If the effective minimum range provided by this method is insufficient to guide the robot100to the final position, the robot controller102can guide the robot100the remaining distance to the docked position DP using odometry or dead reckoning. That is, the robot100uses the image sensor158D and emitters238to guide the robot100to a distance within the effective minimum range, calculates the gap distance from the detected position to the docked position DP, and then drives the robot100forward the gap distance.

In other embodiments, in the fine approach step, the robot100uses odometry or dead reckoning as described above without using the emitters238. That is, the robot100uses the image sensor device158to guide the robot100to a distance within the effective minimum range of the image sensor device158, calculates the gap distance from the detected position to the docked position DP, and then drives the robot100forward the gap distance.

In another embodiment, the robot100uses the magnetic coils164,244to dock. By sensing the magnetic field of the dock side coil244upon approaching the dock200, the robot100can determine alignment of the dock side transmit coil244and robot side receiver coil164.

In other embodiments, in the fine approach step, the robot100uses an onboard bump sensor (e.g., a contact sensor or displacement sensor) to detect when the front end110A of the robot100has made contact with the front wall220A. Upon detecting contact, the robot100may stop or reverse a prescribed distance to position the robot100in the docked position DP.

In other embodiments, the camera159(e.g., a VSLAM camera) is used to detect the dock200in order to guide the robot100in the far approach step. The camera159may also be used to build and use a map using VSLAM technology as discussed above. For example, in some embodiments, the camera159is aimed upward (e.g., to view locations 3-8 feet above the floor) to view objects or features (e.g., picture frames and doorway frames and edges) for mapping and localizing the robot100relative to these landmarks (i.e., groupings of features).

In addition to operating as navigational beacons, homing signals BR, BQ, the avoidance signal BA, and/or the image sensor signals BL, BU may also be used to transmit information, including programming data, fail safe and diagnostic information, docking control data and information, maintenance and control sequences, etc. In such an embodiment, the signals can provide the control information, dictating the robot's reactions, as opposed to the robot100taking certain actions upon contacting certain signals from the dock200. In that case, the robot100functions as more of a slave to the dock200, operating as directed by the signals sent.

In each of the far approach step, the near approach step, and the fine approach step, the robot100may use the navigational aids described herein to adjust the lateral alignment of the robot100with respect to the dock200, the angular orientation of the robot100with respect to the dock200, and/or the depthwise position of the robot100into the dock200(i.e., proximity to the backstop220).

Generally, the control sequence for vacuuming can include three subsequences based on the measured energy level of the robot100. Those are referenced generally as a high energy level, a medium energy level, and a low energy level. In the high energy level subsequence, the robot100performs its predetermined task, in this case, vacuuming (utilizing various behavioral modes as described above), while avoiding the dock200. When avoiding the dock200, the robot100performs its avoidance behavior and continues to operate normally. This process continues while the robot100continually monitors its energy level. Various methods are available to monitor the energy level of the power source, such as coulometry (i.e., the measuring of current constantly entering and leaving the power source), or simply measuring voltage remaining in the power source. Other embodiments of the robot100may simply employ a timer and a look-up table stored in memory to determine how long the robot100can operate before it enters a different energy level subsequence. Still other embodiments may simply operate the robot100for a predetermined time period before recharging, without determining which energy level subsequence it is operating in. If the robot100operates on a liquid or gaseous fuel, this level may also be measured with devices currently known in the art.

Once the energy remaining drops below a predetermined high level, the robot100enters its medium energy level sequence. The robot100continues to vacuum and monitor its energy level. In the medium energy level, however, the robot100“passively seeks” the dock200. While passively seeking the dock200, the robot100does not alter its travel characteristics; rather, it continues about its normal behavioral mode until it detects the avoidance signal BA or a homing signal BR, BQ, each of which may be followed until the robot100ultimately docks with the dock200. In other words, if the robot detects the avoidance signal BA while passively seeking, rather than avoiding the dock200as it normally would, it alters its travel characteristics until it detects the homing signal BR or BQ, thus allowing it to dock.

Alternatively, the robot100continues operating in this medium energy level subsequence until it registers an energy level below a predetermined low level. At this point, the robot100enters the low level subsequence, characterized by a change in operation and travel characteristics. To conserve energy, the robot100may discontinue powering all incidental systems, and operations, such as vacuuming, allowing it to conserve as much energy as possible for “actively searching” for the dock200. While actively searching, the robot100may alter its travel characteristics to increase its chances of finding the dock200. It may discontinue behavioral modes such as those employing a spiral movement, which do not necessarily create a higher chance of locating the dock200, in favor of more deliberate modes, such as wall-following. This deliberate seeking will continue until the robot100detects the presence of the dock200, either by detecting the avoidance signal BA or the homing signals BR, BQ. Clearly, additional subsequences may be incorporated which sound alarms when the power remaining reaches a critical level, or which reconstruct the route the robot100has taken since last contacting the dock200to aid in relocating the dock200.

The robot100may also dock because it has determined that it has completed its assigned task (e.g., vacuuming a room) or its bin needs to be emptied. The robot100may make this determination based on a variety of factors, including considerations regarding room size, total run time, total distance traveled, dirt sensing, etc. Alternatively, the robot may employ room-mapping programs, using the dock200and/or walls and large objects as points of reference. Upon determining that it has completed its task, the robot100will alter its travel characteristics in order to find the dock200quickly. The dock200may include a charging system only (i.e., a charging dock) or may include both a charging system and an evacuation system or station operative to empty debris from the bin of the robot100.

Once the robot100is in the docked position, it can recharge itself autonomously. Circuitry within the dock200detects the presence of the robot100and then switches on the charging voltage to the transmitter coil244.

While docked with the dock200, the robot100can also perform other maintenance or diagnostic checks. In certain embodiments, the robot100can completely recharge its power source or only partially charge it, based on various factors. Other behaviors while in the docking position such as diagnostic functions, internal mechanism cleaning, communication with network, or data manipulation functions may also be performed.

As discussed, herein, the energy management system205uses electromagnetic induction charging to charge the robot100. The use of induction charging can provide a number of advantages as compared to direct electrical contact charging.

The use of induction charging eliminates electrical contacts as points of failure in the system10. The induction charging system makes docking easier and more reliable.

Greater flexibility is provided for industrial design. Induction charging allows for a completely sealed dock.

As discussed herein, in some embodiments the magnetic field from the transmitter coil can be used as a dock avoidance signal to the robot, in which case the dock avoidance sensor of the robot can be omitted.

The induction charging system does not require explicit communication from the charge receiving circuit (on the robot) to the charge transmitter circuit (on the dock) for staying in regulation.

By encasing the receiver coil164and the transmitter coil244in the coil chambers124and216(and, likewise encasing the transmitter coil344in the coil chamber316as described below), the coils164,244,344are isolated from the environment and the interior of the robot100. As a result, people and pets and internal components of the robot100are protected from the voltage of the coils and the coils are protected from damage. Additionally, the transmitter coils244,344are prevented from contacting the receiver coil164. In some embodiments, each coil164,244,344is encased on each of its top and bottom sides by plastic having a thickness in the range of from about 1 to 3 mm.

Various parameters may affect the coupling factor between the receiver and transmitter coils and can be adjusted to improve the coupling factor. The coupling factor is increased by a smaller separation gap, larger coil areas, and more precise alignment. Good alignment is less critical for larger coils. Thicker coil wire improves efficiency.

In some embodiments, the coils are operated at frequencies in the 160-270 kHz range.

The electromagnetic induction charging system205is schematically shown inFIG. 12and includes the robot charging subsystem160and the dock charging subsystem240. When the robot100is docked in the docking bay DB as described, the receiver coil164is superimposed over the transmitter coil244with a vertical or axial gap GC therebetween. In this manner, the coils164,244form an air gap transformer. The circuit242applies an alternating current through the transmitter coil244, thereby creating an alternating magnetic field (flux) emanating from the transmitter coil244. The flux is received and converted into an electrical current by the receiver coil164. This electrical current is used by the circuit162to charge the battery126or otherwise provide energy to the robot100.

The efficiency of the induction charging (both energy transfer rate and power loss) is dependent on the alignment and spacing between the coils164,244. The docking modes, methods, structures and sensors as described herein can ensure that the robot100is consistently properly docked in the docked position DP, and the coils164,244are thereby properly aligned.

In some embodiments, when the robot100is in the docked position DP, the coils164,244lie in substantially parallel planes. In some embodiments, the coil164defines a receiver coil plane PRC (FIG. 2), and the coil244defines a transmitter coil plane PTC, and the planes PRC and PTC are parallel or form an angle with respect to one another no greater than 10 degrees.

When the robot100is in the prescribed docked position DP (FIGS. 1 and 2), the coil164is located in a prescribed vertical alignment position with respect to the coil244. In some embodiments, the central axis RCA of the coil164is substantially coaxial with the central axis TCA of the coil244. In some embodiments, the axis RCA is disposed within 5 mm of the axis TCA in the receiver coil plane PRC and, in some embodiments, within 30 mm.

In other embodiments, when the robot100is in the docked position DP, the transmitter coil axis TCA intersects the receiver coil plane PRC at a location that is offset a prescribed offset distance from the receiver coil axis RCA, and the transmitter coil244vertically overlaps the receiver coil164. In some embodiments, the prescribed distance is no greater than about 5 mm and, in some embodiments, is in the range of from about 5 mm to 30 mm.

Notably, the transmitter coil244is horizontally located in the platform212such that the transmitter coil center axis TCA is offset from the center or midline of the platform212in order to more closely align the center axes RCA, TCA of the receiver coil164and the transmitter coil244when the robot100is in the docked position DP.

The offset of the receiver coil164accommodates the evacuation port318of the dock300.

Moreover, the placement of the receiver coil164in the undercarriage115of the robot100and the placement of the transmitter coil244in the platform212can provide a relatively small axial gap GC (FIG. 2) between the coils164,244. Nonetheless, the coils164,244are each protected from the environment by being enveloped in the coil chambers124,216. A smaller gap enables improved energy transfer efficiency. In some embodiments, the gap GC has a height E10of 7 mm or less.

According to some embodiments, the robot charging subsystem160and the dock charging subsystem240operate as follows. The dock charging circuit (“transmitter firmware”)242assumes the following main states: Ping, Handshaking, and Charging. Generally, the dock charging circuit242“pings” periodically (e.g., approximately every ⅓ second) to determine whether the robot100is on the dock200, confirms the presence of the robot100, and determines whether to send a full charge.

In Ping mode, the dock charging circuit242starts the coil244oscillating, and measures how long it takes to stop oscillation to detect when a real robot is present, when there is a foreign object absorbing power (“snow shovel” detection), and when there is nothing near the dock.

In Handshake mode, the dock charging circuit242listens for an authentication word from the robot100by observing differences in power consumed when running power for a short duration.

In Charging mode, the power sent is controlled by the dock charging circuit242for efficiency and to keep the electronics in valid operating regions (current and voltage). In particular, in Charging mode the dock charging circuit242sends power using voltage-feedback-current-control until the dock charging circuit242detects the receiver (i.e., the robot charging circuit162) detuning, and then stops sending power for a variable amount of time. The amount of time that power is off is dynamically adjusted based on how long the receiver consumed power before detuning.

Cycle-by-cycle control of the dock charging circuit242may be performed in an interrupt handler that runs on every cycle of the transmit coil (in some embodiments, approximately 200 KHz or every 5 μs). Every cycle the interrupt handler determines what current to send to the transmitter coil244on the next cycle by adjusting the current limit (called “limit” in the diagrams) or completely turning off adding energy the next cycle (called enabling the “dead” signal in the diagrams). The high level control code described determines which of these interrupt handlers should run to manage the transmitter coil244depending on the high level state of the dock charging circuit242.

The “Charging Resonant Tank” state is the main mode when sending power to the robot100. In this mode, the dock charging circuit242adjusts the current limit until the dock charging circuit242detects the robot charging circuit162detune. When it does, it enters the “Idle” state which triggers the background code to measure the amount of time the receiver coil164was drawing power and sleep for the calculated amount of time.

The “Hard Start” state and “Decaying” state are transient states while transferring power. The dock charging circuit242initially enters “Hard Start” state, and will move between “Charging Resonant Tank” state and “Decaying” state while transferring power until it enters “Idle” state when the robot charging circuit162detunes.

After starting and sending the authentication code, the robot charging circuit162checks that power is coming in. Assuming it is, the robot charging circuit162enters the main loop where it detunes when the system voltage exceeds some threshold. How long it takes for this to happen will depend on the power being drawn from the robot charging circuit162(i.e., whether it is charging a battery, and how much power is being sent to the battery). The robot charging circuit162then detunes briefly, which the dock charging circuit242will detect, and then retunes to accept power when the dock charging circuit242next decides to send it.

In some embodiments, the magnetic field emitted from the transmitter coil244and the tank circuit of the dock charging circuit242is also used in the navigation control of the robot100. The robot100will detect the magnetic charge that accompanies the “ping” generated by the dock charging circuit242. The robot100can use that detection to avoid the dock200(e.g., while the robot is moving about on its cleaning mission) or discover the dock200(to initiate docking). According to some embodiments, the detection radius is in the range of from about 6 to 18 inches from the dock200and, in some embodiments, 10 to 14 inches.

In some embodiments, the magnetic field sensor155on the robot100is used to detect the ping signals. The sensor155may be used to detect the ping signals independently of the robot's receiver coil164and charging circuit162. The magnetic field sensor155may include a first magnetic sensing circuit155A and a second magnetic sensing circuit155B. The magnetic sensing circuits155A,155B may each be small LC circuits with high gain amplifiers. The inductor coil of the first magnetic sensing circuit155A may be oriented in the Z-direction (vertically) so that it provides a signal roughly proportional to the distance to the transmitter coil244. The inductor coil of the second magnetic sensing circuit155B may be oriented in the X- or Y-direction (left-to-right, fore-aft, or horizontally) so that it provides a signal roughly proportional to the orientation to the transmitter coil244.

The magnetic field sensor155may also be used to determine where the robot100is located in the magnetic field of the dock transmitter coil244during docking. In this manner, detection from the magnetic field sensor155can be used to execute the far approach step in place of or in addition to data provided by the front directional detector156.

The magnetic field sensor155may also be used to confirm that the coils164,244are sufficiently well-aligned once the robot100is fully docked. This can enable improved alignment between the coils164,244, and thereby guarantee good efficiency in the coupling to achieve good power transfer.

In some embodiments, the robot100is aligned with the dock200, and thereby the coil164is aligned with the coil244, along the X-axis and along the Y-axis with a tolerance of ±25 mm or less, in some embodiments, ±5 mm or less and, in some embodiments, about ±1 mm. In some embodiments, the tolerance for alignment of the coils164,244along the Z-axis is 20 mm or less (i.e., the coil164is not spaced above the coil244more than 20 mm, and the coils164,244are as close together as feasible).

FIGS. 13 and 14show an evacuation dock300in accordance with one embodiment of the invention. The evacuation dock300includes a housing311including both a substantially horizontal base plate or platform310and a substantially vertical tower or backstop320. A docking bay DB is defined over the platform310and in front of the backstop320. The evacuation dock300may be any of a variety of shapes or sizes, providing sufficient space for the desired components and systems, described below.

The platform310includes a coil chamber316defined therein. The coil chamber316is defined by the wall312and a lower wall315. A raised pad wall312overlies the coil chamber316. Parallel tracks314are defined on either lateral side of the coil chamber316and the pad wall312. An evacuation suction port318is defined in the pad wall312. The evacuation suction port318is offset from the lateral centerline of the platform310and the midpoint between the tracks314.

The platform310is sloped at an upwards angle toward the backstop320. In some embodiments, the platform310angle of rise is in the range of from 6 to 10 degrees, in some embodiments, 8 to 10 degrees and, in some embodiments, about 8.6 degrees.

The evacuation dock300includes a charging subsystem340, a communications/guidance system330, a dock controller322, and a power input connector324(connected to a power supply, not shown) corresponding to and operative in the same manner as the charging subsystem240, the communications/guidance system230, the dock controller222, and the power input connector224, respectively, except as discussed below. The evacuation dock300includes an avoidance emitter332, directional emitters334R,334L, and a pair of fine alignment emitters338corresponding to the avoidance emitter232, the directional emitters234R,234L, and the emitters238, respectively.

The charging subsystem340includes a charging circuit342and a transmitter coil344corresponding to the charging circuit242and the transmitter coil244. The coil344is encased in the coil chamber316in the same manner as described above with regard to the coil chamber216and the coil244. The coil344is tilted or oriented at an oblique angle A1(FIG. 14) with respect to the floor toward the backstop320. In some embodiments, the angle A1is in the range of from about 6 to 10 degrees, in some embodiments, 8 to 10 degrees and, in some embodiments, about 8.6 degrees. The central axis RCA of the coil344is offset from the midline X-X of the platform310to match the offset of the coil164.

The evacuation dock300further includes a debris evacuation system350. The evacuation system350includes a debris bin352(which may be removable) in the tower320, an evacuation port318located in the platform310, a duct or ducts fluidly connecting the port318to the bin352, and a suction fan354configured to draw debris from the evacuation port318and into the bin352.

The wheel tracks314are designed to receive the robot's drive wheels132to guide the robot100onto the platform310in proper alignment with the evacuation suction port318. Each of the wheel tracks314includes a depressed wheel well319that holds a drive wheel132in place to positively align and locate the robot100relative to the platform310, and to prevent the robot100from unintentionally sliding down the inclined platform310once docked.

The robot100can dock with the evacuation dock300by advancing onto the platform310and into the docking bay DB of the evacuation station300as described above with regard to the dock200. Once the evacuation dock300receives the robot100, the suction fan354generates a vacuum that draws debris from the cleaning bin145of the robot100, through the platform310, and into the debris bin352.

When the robot100is docked in the prescribed docked position in the docking bay DB, the coils164will be superimposed over and suitably vertically aligned with the coil344. Additionally, the evacuation port120of the robot100will be aligned with and in contact with or in close proximity to the evacuation port318of the evacuation dock300.

The robot100can avoid, discover, far approach, near approach, and fine approach the evacuation dock300in the same manner as described above with regard to the dock200. It is also contemplated that the fine alignment emitters338may be omitted. The robot may rely on the wheel wells319to capture the wheels132, thereby positively aligning and positioning the robots and ensuring that the robot is properly aligned in the final portion of the docking approach. The image sensor device158can be used to ensure that the wheels132do not over- or under-run the wheel wells.

The magnetic field sensor155may also be used to detect magnetic ping signals from the coil344to guide the robot100as described above for the dock200.

In some embodiments, the robot100is aligned with the evacuation dock300, and the coil164is thereby aligned with the coil344, along the X-axis and along the Y-axis with a tolerance of about ±1 mm. The evacuation dock300requires close alignment of the evacuation port120of the robot with the suction port318of the evacuation dock300, and therefore the tolerance for misalignment may be very small and less than the tolerance permitted for the dock200. In some embodiments, the tolerance for alignment of the coils164,344along the Z-axis is about ±1-20 mm.

With reference toFIGS. 15-17, a lawn mowing robot system20according to embodiments of the invention is shown therein. The system20includes a lawn mower robot and a charging dock500. The robot400includes a robot charging subsystem460and the dock500includes a dock charging subsystem560, which together form an induction charging system505.

The robot400further includes a robot controller402, a chassis410, a cutting deck414, a cover412, a battery426, a motive system430, and a cutting system440. The chassis410, the cutting deck414, and the cover412form a robot body, housing infrastructure or housing.

The motive system430includes a pair of independently driven wheels434, a pair of caster wheels435, a motor434A to drive the wheels434, and an automatic height adjuster436.

The cutting system440includes at least one cutting element suspected from the bottom of the body of the robot100. As shown, the cutting system440includes a pair of rotary cutting blades444suspended from the bottom of the cutting deck414and an electric motor442to drive the blades444.

The robot charging subsystem460includes a charging circuit462and a receiver coil464generally corresponding to the charging circuit162and a receiver coil164.

The coil464is contained in a receiver coil chamber424defined in the cutting deck414. The cutting deck414or chassis410includes a bottom wall410C defining a portion of the receiver coil chamber424. In some embodiments, the bottom wall410C has a nominal thickness of at least 2 mm. The bottom wall410C separates the coil464from the underlying surface (e.g., the ground or objects). In some embodiments, the center axis RCA-RCA is centered on the fore-aft central axis FA-FA of the robot400.

The dock500includes a housing511, ground anchors or spikes512, the dock charging subsystem540, a homing system530, and a dock controller522.

The housing511includes a base510and a cover514. The base510and the cover514collectively form an enclosed chamber516.

The dock charging subsystem540includes a charging circuit542and a transmitter coil544generally corresponding to the charging circuit242and a transmitter coil244. The transmitter coil544is contained in the chamber516. The cover514includes a top wall514A defining a portion of the chamber516. The top wall514A separates the coil544from the robot400or other overlying objects. In some embodiments, the top wall514A has a nominal thickness of at least 2 mm.

The robot400can be used to autonomously mow a lawn. When the robot400has completed its mowing session or requires a recharge, it will seek the dock500.

In some embodiments, the robot400uses localization beacons about the lawn to triangulate into the vicinity of the dock500. In some embodiments, the robot400is configured to align with the dock500using the magnetic charge emitted by a periodic pinging of the dock charging circuit542, such as described above with regard to the magnetic field sensor155and the dock charging circuit242. In some embodiments, the robot400includes a Hall Effect sensor which is used to sense the magnetic charge ping, enabling the robot controller402to align the robot400with the dock500as the robot400approaches its prescribed docked position over the dock500.

When the robot400is in its prescribed docked position over the dock500, the receiver coil464and the transmitter coil544will be substantially vertically aligned, overlapping or in near proximity. In some embodiments, the robot400is positioned over the dock500such that the central axis RCA-RCA of the receiver coil464is aligned or brought into close proximity to the central axis TCA-TCA of the transmitter coil544. The robot400may lower the cutting deck414relative to the chassis510and the wheels435, and thereby the coil464, using the height adjuster436. In this manner, the receiver coil464is brought into closer proximity to the transmitter coil544. In some embodiments, the cutting deck414is lowered into contact with the dock500.

The robot charging subsystem460and the dock charging subsystem540can thereafter cooperate to inductively charge the robot400in the same manner as described above with regard to the robot charging subsystem160and the dock charging subsystem240.

The coils164,244,344,464,544may be formed of any suitable material and construction. In some embodiments, one or more of the coils is/are formed of wound copper wire. In some embodiments, one or more of the coils is/are formed of stamped copper. In some embodiments, one or more of the coils is/are formed of wound aluminum wire. In some embodiments, one or more of the coils is/are formed of wound Litz wire (copper or aluminum).

In some embodiments, the vertical spacing distance between the coils164and244and between the coils164and344when the robot is docked us less than 20 mm.

In some embodiments, the coil164is 1.25 mm thick, has 22 windings, an inner diameter of 58 mm, and an outer diameter of 117 mm.

In some embodiments, the receiver coil164(“Rx Coil”) and the transmitter coils244,344(“Tx Coil”) have the following characteristics:

In some embodiments, the receiver coil164(“Rx Coil”) and the transmitter coils244,344(“Tx Coil”) are stamped aluminum coils having the following characteristics:

In some embodiments, the receiver coil464(“Rx Coil”) and the transmitter coil544(“Tx Coil”) of the robotic lawn mower system20have the following characteristics: