Patent ID: 12256876

Like reference numerals in different figures indicate like elements.

DETAILED DESCRIPTION

Described herein are example robots configured to traverse (or to navigate) surfaces, such as floors, carpets, or other materials, and to perform various cleaning operations including, but not limited to, vacuuming. Also described herein are examples of evacuation stations, at which the mobile robots can dock to evacuate debris stored in debris bins on the mobile robots. Referring to the example ofFIG.1, a mobile robot100is configured to execute a cleaning operation to ingest debris as the mobile robot navigates about a surface105of an environment110. The ingested debris is stored in a debris bin115on the mobile robot100. The debris bin115becomes full after the mobile robot100has ingested a certain amount of debris.

After the debris bin has become full, the mobile robot can navigate to and dock at an evacuation station120. Generally, an evacuation station can additionally serve as, for example, a charging station and a docking station. The evacuation station includes a base station configured to remove debris from the debris bin, and to perform other functions vis-à-vis the mobile robot, such as charging. The evacuation station includes a control system, which can include one or more processing devices that are programmed to control operation of the evacuation station. In this example, the evacuation station120is controlled to generate negative air pressure to suction ingested debris out of the debris bin115and into the evacuation station120. As part of the evacuation operation, the debris is directed into a removable bag (not shown inFIG.1) housed in a canister125in the evacuation station120. Between the debris bin115and the bag, the evacuation station120includes conduits (not shown inFIG.1) that allow debris to pass from the debris bin115and into the bag. As described herein, the conduits can include a removable conduit that can be removed and cleaned, and a movable conduit that is controllable to move into, and out of, contact with the bag. Following evacuation, the mobile robot100can undock from the evacuation station120, and execute a new cleaning (or other) operation. The evacuation station120also includes one or more ports, to which the mobile robot100interfaces for charging.

FIG.2shows a cut-away side view of a mobile robot and an evacuation station of the type shown inFIG.1. InFIG.2, a mobile robot200is docked at an evacuation station205, thereby enabling the evacuation station205and the mobile robot200to communicate with one another (e.g., electronically and optically), as described herein. The evacuation station205, also depicted inFIG.3, includes a base206to receive the mobile robot200to enable the mobile robot200to dock at the evacuation station205. The mobile robot200may detect that its debris bin210is full, prompting the mobile robot200to dock at the evacuation station205so that the evacuation station205can evacuate the debris bin210. The mobile robot200may detect that it needs charging, also prompting the mobile robot200to return to the evacuation station205for charging.

Both the mobile robot200and the evacuation station205include electrical contacts. On the evacuation station205, the electrical contacts245are located along a rearward portion246of the base opposite to an intake port227located along a forward portion247. The electrical contacts240on the mobile robot200are located on a forward portion of the mobile robot200. Electrical contacts240on the mobile robot200mate to corresponding electrical contacts245on the base206when the mobile robot200is properly docked at the evacuation station205. The mating between the electrical contacts240and the electrical contacts245enables communication between the control system208on the evacuation station and a corresponding control system of the mobile robot200. The evacuation station205can initiate an evacuation operation and, in some cases, a charging operation, based on those communications. In other examples, the communication between the mobile robot200and the evacuation station205is provided over an infrared (IR) communication link. In some examples, the electrical contacts245on the mobile robot200are located on a back side of the mobile robot200rather than an underside of the mobile robot200and the corresponding electrical contacts245on the evacuation station205are positioned accordingly.

For example, when the electrical contacts240,245are properly mated, the evacuation station205can issue a command to the mobile robot200to initiate evacuation of the debris bin210. In some examples, the evacuation station205sends a command to the mobile robot200and will only evacuate if the mobile robot200completes a proper handshake (e.g., electrical contact between the electric contacts240and the electrical contacts245). For example, the control system208can send a communication to the mobile robot200, and receive a response to this communication from the mobile robot200and, in response, initiate an evacuation operation of the debris bin210. Additionally or alternatively, when the electrical contacts240,245are properly mated, the control system208can execute a charging operation to restore, wholly or partially, the power source of the mobile robot200. In other examples, when the electrical contacts240,245are properly mated, the mobile robot200can issue a command to the evacuation station205to initiate evacuation of the debris bin210. The mobile robot200can transmit the command to the evacuation station205through electrical signals, optical signals, or other appropriate signals.

Also, when the electrical contacts240,245are properly mated, the mobile robot200and the evacuation station205are aligned so that the evacuation station205can begin the evacuation operation. For example, the intake port227of the evacuation station205aligns with an exhaust port225of the debris bin210. Alignment between the intake port227and the exhaust port225provides for continuity of a flow path222, along which debris215travels between the debris bin210and a bag235in the evacuation station205. As described herein, the debris215is suctioned by the evacuation station205from the debris bin210into the bag235, where it is stored.

In this regard, the evacuation station includes a motor218connected to the canister220. The motor218is configured to draw air out of the canister220, and through bag235, which is air permeable. As a result, the motor218can create a negative air pressure within the canister220. The motor218responds to commands from the control system208to draw air out of the canister220. The motor218expels the air drawn out of the canister220through an exit port223on the canister220. As noted, the removal of air generates negative air pressure in the canister220, which evacuates the debris bin210by generating an air flow along the flow path222that suctions the debris215. In this example, the debris215moves along flow path222from the debris bin210, through a door unit (not shown) on the debris bin210, through the exhaust port225on the debris bin210, through intake port227on the base206, through multiple conduits230a,230b,230cin the evacuation station205, and into the bag235.

Air is expelled by the motor218through an exhaust chamber236housing the motor218and through the exit port223into the environment. The bag235can be an air permeable filter bag that can receive the debris215travelling along the flow path222—which can include flows of, for example, air and debris215—and separate the debris215from air. The bag235can be disposable and formed of paper, fabric, or other appropriately porous material that allows air to pass through but traps the debris215within the bag235. Thus, as the motor218removes air from the canister220, the air passes through the bag235and exits through the exit port223.

The evacuation station205also includes a pressure sensor228, which monitors the air pressure within the canister220. The pressure sensor228can include a Micro-Electro-Mechanical System (MEMS) pressure sensor or any other appropriate type of pressure sensor. A MEMS pressure sensor is used in this implementation because of its ability to continue to accurately operate in the presence of vibrations due to, for example, mechanical motion of the motor218or motion from the environment transferred to the evacuation station205. The pressure sensor228can detect changes in air pressure in the canister220caused by the activation of the motor218to remove air from the canister220. The length of time for which evacuation is performed may be based on the pressure measured by the pressure sensor228, as described with respect toFIG.4.

FIG.4depicts an example graph400of air pressure405generated over a period of time410in response to the removal of air from canister220. The air pressure405, before activation by motor218, can be atmospheric air pressure. The initial activation of the motor218can cause an initial dip415in the air pressure405. This initial dip415can occur due to a cracking pressure needed to initially open a flap or door of the door unit on the debris bin. More particularly, the initial dip415can be associated with the flap including a biasing mechanism that requires a first air pressure to move initially from a closed position to an open position that is higher than a second air pressure to maintain the flap in the open position.

As the motor218continues removing air and drawing debris215into the bag235, fluctuations420may occur in the air pressure405due to the movement of the debris215through the flow path222. That is, the debris215can cause partial occlusions of the flow path222that can cause the air pressure405to experience the fluctuations420. The partial occlusions can cause the fluctuations420to include decreases in the air pressure405. In some cases, during the evacuation operation, the air pressure405can clear the partial occlusions and decrease resistance to the air flow. The fluctuations420may thus include increase in the air pressure405after the partial occlusions are cleared. In addition, movement of the debris215within the bag235can cause changes in flow characteristics of the air, also resulting in the fluctuations420. As the debris215continues filling the bag235, the air pressure405increases due to the debris215impeding air flow through the canister220.

When the debris215is mostly or completely evacuated from the debris bin210, the bag235does not continue to fill with debris, thus resulting in a steady state425for the air pressure405. In this context, steady state425may include a constant pressure or fluctuations relative to a constant pressure that do not exceed a certain percentage, e.g., 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, etc., over the course of a period of time. The control system208can determine that the air pressure405has reached the steady state425by monitoring the air pressure405for a predefined period of time430following a start of evacuation. The air pressure405can be detected by the pressure sensor228which, in turn, can generate and transmit air pressure signals to the control system208for the processing. The control system208may use these pressure signals to determine when to terminate debris bin evacuation. In this regard, it can be advantageous to reduce the amount of evacuation time, since evacuation can be a relatively noisy process, and since evacuation time cuts-into cleaning time. Furthermore, in some cases, the majority of debris215is suctioned from the debris bin210within a fraction of the overall programmed evacuation time, making at least some of that time unnecessary. In some instances, the programmed evacuation time is 30 seconds, whereas the majority of debris is actually evacuated from the debris bin210within 5 seconds.

As shown inFIG.4, upon entry into the steady state condition425, the control system208continues to control the motor218to cause the motor218to continue to apply the negative air pressure. This negative air pressure is applied for the predefined period of time430, during which the air pressure405is maintained within a predefined range435(e.g., a range defined by a two-sided hysteresis). After that predefined period of time430, if the air pressure405remains stable (e.g., within the predefined range435), the control system208sends commands to stop operation of the motor218, thereby terminating evacuation. The motor218then stops removing air from the canister220, causing the air pressure405to return to atmospheric pressure. The predefined period of time430can be, for example, 3 seconds, 4 seconds, 5 seconds, 6 seconds, 7 seconds, 8 seconds, 9 seconds, 10 seconds, 11 seconds, 12 seconds, 13 seconds, 14 seconds, 15 seconds, etc. The predefined range435can be, for example, plus or minus 5 Pa, 10 Pa, 15 Pa, 20 Pa, etc. The predefined period of time430and the predefined range can be stored on a memory storage element operable with the control system208.

In some implementations, the steady state air pressure405can decrease below a threshold pressure440, which indicates that the bag235has become substantially full of debris. In some implementations, as atmospheric conditions, debris, and other conditions will vary, the trend in the steady state air pressure405over multiple evacuations would be used to indicate that the bag235has become substantially full of debris. A combination of a threshold pressure440and the trend of the steady state air pressure405is used in some implementations. The steady state air pressure405decreases as the bag235fills and it becomes more difficult to pull air through the bag235. The threshold pressure440can be pre-determined (e.g., stored in a memory storage element accessible by the control system208) or it can be adjusted by the control system208based on a baseline reading of the steady state air pressure405when a new bag235is installed. The control system208can determine, for example, when the steady state air pressure405is below the threshold pressure440, the trend in the steady state air pressure405over multiple evacuations is sufficiently sloped, or any combination thereof, and can then transmit instructions for an operation in response to the air pressure405exceeding the threshold pressure440. For example, the control system208can transmit commands to the motor218to end evacuation of the debris215, thus causing the air pressure405to return to atmospheric pressure. The threshold pressure440can between, for example, 600 Pa to 950 Pa, but this will depend on conditions in the system and environment. The threshold pressure440can indicate percent volume of the bag235occupied by the debris215between, for example 50% and 100%. Upon detecting that the bag235is full, the control system208can also output instructions to a computer system, such as a server, which maintains a user account and which can notify the user that the bag is full and needs to be changed. For example, the server can output the information to an application (“app”) on the user's mobile device, which the user can access to monitor their home system. In some examples, a second threshold pressure (e.g., a notification pressure) can be used to notify the user that the bag235is nearing the full state and a limited number of additional evacuations will be possible prior to replacement of the bag235. Thus, the system can notify the user and allow the user to replace the bag235prior to the bag235being too full to allow evacuation of the robot bin.

By monitoring the air pressure405in the canister220using the pressure sensor228, the control system208can adaptively control an amount of evacuation time445that the control system208operates the motor218and, therefore, the amount of time that evacuation of the debris bin210occurs. For example, the point in time when the air pressure405exceeds the threshold pressure440and/or the point in time when the air pressure405is maintained within the predefined range435for the period of time430can dictate when evacuation ends. In some implementations, the control system208can control the evacuation time445to be between 15 seconds and 45 seconds. The air pressure405, and thus the evacuation time445, can depend on a number of factors such as, but not limited to, an amount of debris stored in the debris bin210and flow characteristics caused by, e.g., the size, viscosity, water content, weight, etc. of the debris215.

FIG.5shows a flow chart of an example process500in which a control system (e.g., the control system208) operates a motor (e.g., the motor218) of an evacuation station (e.g., the evacuation station205) based on electrical contact signals and air pressure (e.g., the air pressure405) in a canister (e.g., the canister220) of the evacuation station.

At the start of the process500, the control system receives (505) electrical contact signals. The electrical contact signals indicate that a mobile robot is docked at the evacuation station. In some examples, the electrical contact signals can indicate that electrical contacts of a mobile robot are in electrical and physical contact with electrical contacts of the evacuation station.

After receiving the electrical contact signals, the control system sends (507) optical start signals to initiate evacuation via, for example, an optical communication link. In some cases, the mobile robot transmits the optical start signals using the optical communication link. Because the electrical contacts of the mobile robot are in contact with the electrical contacts of the evacuation station, the mobile robot is properly aligned with the evacuation station for the evacuation station to initiate the evacuation process by transmitting the optical start signals directly to the mobile robot. The mobile robot acknowledges the start optical signal with an acknowledgement optical signal to the evacuation station before the control system begins evacuation.

The control system then transmits (510) commands to begin evacuation. The control system can transmit (510) the commands to begin evacuation after receiving the optical acknowledgement signal from the mobile robot to begin the evacuation. In some examples, the evacuation station detects the received (505) electrical contact signals and transmits (510) commands to begin the evacuation after detecting the received (505) electrical contact signals. The evacuation station thus does not receive optical start signals from the mobile robot to begin evacuation. In some implementations, the control system does not receive (505) electrical contact signals when the electrical contacts mate. The controller of the mobile robot can receive the electrical contact signals and then transmit the optical start signals to the control system in response to the electrical contact signals.

The commands transmitted (510) by the control system can instruct the motor to activate as described herein. Specifically, the motor suctions air out of the canister of the evacuation station to generate a negative air pressure within the canister. The resulting negative air pressure extends along the flow path and into the robot's debris bin, causing suction of the debris from the robot's debris bin, through the flow path, and into an air permeable bag held in the canister.

The control system continues transmitting (515) the commands, thereby continuing operation of the motor and evacuation of debris. During operation of the motor, the control system can modify the power delivered to the motor to increase or decrease the amount of negative air pressure generated within the canister.

The control system continues to receive (520) air pressure signals from the pressure sensor in the canister while evacuation continues. The measured air pressure signals vary due to variations in amounts of debris within the bag, blockage of the flow path, or the like.

Based on the air pressure signals, the control system determines (525) whether the air pressure within the canister has reached steady state. To determine (525) whether the air pressure has reached steady state, the control system determines that it has received air pressure signals indicating a pressure within a defined range for at least predefined amount of time. If the control system determines that the air pressure has been in the steady state for the predefined amount of time, the control system can transmit (527) commands to end evacuation. If the control system determines (539) that the air pressure has not reached steady state air pressure, the control system can continue transmitting (515) commands for evacuation, receive (520) air pressure signals, and determine (525) whether to transmit (527) instructions to end evacuation. In other examples, the control system can have a pre-set evacuation time (length of evacuation). In such situations, the control system does not determine the completion of evacuation based on the pressure sensor signals.

The system also determines (529) whether the steady state air pressure is (a) indicative of a non-full bag condition (b) in a range for notification of a bag that is reaching a full state, or (c) indicative of a bag full condition based on a comparison of the steady state air pressure to a threshold. If the control system determines that the air pressure exceeds both the notification and bag full threshold pressures, the control system awaits (530) the next evacuation process. If the control system determines (529) that the air pressure is below the notification threshold but above the bag full threshold pressure, the control system transmits (532) a notification to the user indicating that the bag is close to being full. If the control system determines (529) that the air pressure is below the bag full threshold pressure, the control system transmits (532) a notification to the user indicating that the bag is full and prohibits (534) further evacuation of the bin until the bag is replaced.

As described herein, motor218generates negative air pressure in the canister220to create air flow along the flow path222to carry the debris215from the debris bin210to the bag235held in the canister220. And, as described herein with respect to, for example,FIGS.4and5, the control system208uses air pressure monitored by the pressure sensor228to determine the evacuation time445that the control system208activates the motor218to evacuate the bag235. Thus, sealing the air pressure of the canister220and the multiple conduits230a,230b,230cfrom the environment can be advantageous so that the motor218operates more efficiently and so that the air pressure detected by the pressure sensor228can predictably inform the control system208of status of the evacuation operation.

In some examples as shown inFIGS.3,6and7, the intake port227of the evacuation station205includes a rim600defining a perimeter of the intake port227and a seal605inside of the rim600. The seal605is disposed within the intake port227, and is below the rim600(e.g., between 0.5-1.5 mm below the rim). However, the seal605is not fixed relative to the intake port227or the rim600, and is movable relative thereto, e.g., in response to negative air pressure experienced through the flow path. The rim600can be located at a forward portion247of the evacuation station205so that, when the mobile robot200docks at the evacuation station205, the intake port227aligns with the exhaust port225of the debris bin210.

In the absence of the negative air pressure such as when the mobile robot200is not docked at the evacuation station205, as shown inFIG.7, the seal605is protected from contact and frictional forces due to the mobile robot200docking at the evacuation station205. The geometry of the rim600and the seal605can reduce wear of the rim600and the seal605when the mobile robot200moves over the rim600to dock at the evacuation station205. A height700of the rim600is greater than a height705of the seal605such that, when the mobile robot200passes over the rim600, the underside of the mobile robot200does not contact the seal605. In the absence of the negative air pressure, the height705of the seal605is thus below an upper surface707of the rim600. The height700can also be less than a clearance800of an underside805of the mobile robot200, as shown inFIG.8. As a result, the mobile robot200can pass over the rim600when the mobile robot200docks at the evacuation station205.

The seal605may be made of a deformable material that can be movable relative to the rim600in response to forces caused by, for example, the negative air pressure generated by the motor218. The material can be, for example, a thin elastomer. In some implementations, the elastomer ethylene propylene diene monomer (EPDM) rubber, silicone rubber, polyether block amides, Chloropene rubber, Butyl rubber, among other elastomeric materials. In the presence of the negative air pressure in the flow path during an evacuation operation, the seal605can respond to the negative air pressure generated during the evacuation operation by moving upward, toward the mobile robot200, and deforming to form an air-tight seal with the mobile robot200. In an example, the seal605conforms to a shape of the mobile robot200in an area surrounding the exhaust port225of the debris bin210. The seal605has a width that is relative to the separation between the evacuation station205and the mobile robot200when the mobile robot200is located on the evacuation station205such that the seal605can extend upwardly to contact the underside805of the mobile robot200(e.g., 0.5 cm to 1.5 cm)

As shown inFIG.6, in some examples, the seal605includes one or more slits610that allow the seal605to deform upward at corners of the seal605without generating excessive hoop stress in the seal605due to the upward deformation. The slit610can thus increase a lifespan of the seal605and increase the number of or duration of evacuation operations executed by the evacuation station205.

The seal605and the rim600cooperate to provide an air-tight seal between the debris bin210and the evacuation station205that is durable. In some implementations, the seal605can be replaceable. A user can remove the seal605from the rim600and replace the seal605.

In some implementations, each of the conduits230a,230b,230c, in addition to providing a continuous flow path222for transporting debris, can include features that improve ease of operation, manipulation, and cleaning of the evacuation station205. As shown inFIGS.2and9, for example, the conduit230aextends partly along a bottom900of the base206. In some cases, the conduit230aextends partly upward (e.g., along the z-axis) along the evacuation station205, connecting the debris bin210to the conduit230b. The conduit230bextends upward from the conduit230a, connecting the conduit230ato the conduit230c. Flexible grommets905connect the conduit230bto the conduit230c. The conduit230cextends upward from the conduit230band connects the conduit230cto the bag235.

The conduit230acan be sized, and dimensioned, such that a ramp907, shown inFIG.3and described herein, can have a lower height along the forward portion247. In an example, the conduit230acan have a cross-sectional shape that transitions from at least partly rectangular to at least partly curved. As shown inFIG.10, a portion1000aof the conduit230aadjacent to the intake port227can have a cross-sectional shape1005athat is rectangular, and a portion1000cof the conduit230aadjacent to the canister220can have a cross-sectional shape1005cthat is either circular or at least partly curved. In some implementations, the cross-sectional shape1005cis partly circular. A portion1000bof the conduit230acan have a transitional cross-sectional shape1005bthat gradually transitions from the cross-sectional shape1005ato the cross-sectional shape1005cto reduce sharp geometries within the conduit230a. The transitional cross-sectional shape1005bcan be partly curved, partly rectangular, partly circular, or combinations thereof. The cross-sectional shape1005acan have a smaller height than the cross-sectional shape1005band the cross-sectional shape1005cso that the ramp907can have increasing height going from the forward portion247toward the rearward portion246.

The conduit230acan include cross-sectional areas that remain constant between the intake port227and the conduit230bto facilitate non-turbulent air flow through the flow path222. The cross-sectional area of the cross-sectional shapes1005a,1005b,1005ccan be substantially constant throughout the length of the conduit230ato reduce influence of geometry on flow characteristics through the conduit230a.

The conduit230acan be a transparent, removable conduit and/or a replaceable conduit in order to facilitate cleaning the debris215from the evacuation station205. A user can remove the conduit230aand clean an interior of the conduit230ato remove, for example, debris clogs trapped within the conduit230a. The conduit230acan be fastened to the base206using removable fasteners, such as, for example, screws, reversible snap fits, tongue and groove joints, and other fasteners. The user can remove the fasteners and then remove the conduit230afrom the base206to clean the interior of the conduit230a.

The conduits230b,230cincludes pipes that move relative to one another. In an example, the conduit230bis a stationary pipe, and the conduit230cis a movable pipe. Referring toFIG.9, a flexible grommet905provides a flexible interface between the conduit230band the conduit230c. In some implementations, the evacuation station205can include one or more flexible grommets905. The conduit230cpivots at the interface between the conduit230cand the conduit230bbecause of the flexibility of the grommet905.

The conduit230ccan be moved into position to interface with the bag235to establish the continuous flow path222between the debris bin210and the bag235. In some implementations, as shown inFIGS.11to13, to move the conduit230crelative to the conduit230b, the evacuation station205can include a cam mechanism1100(shown inFIGS.12and13) and a plunger1105located within the canister220. The cam mechanism1100can include levers, cams, shuttles, and other components to transfer kinematic motion from the plunger1105to the conduit230c. The plunger1105can be an elongate component that moves axially (e.g., along the z-axis1506Z ofFIG.3).

The cam mechanism1100controls movement of the conduit230cbased on movement of the plunger1105of the evacuation station205. In this regard, a top1110of the canister220can be movable between an open position (FIG.12), and a closed position (FIG.13). Movement of the top1110from the open position to the closed position actuates the plunger1105which in turn causes the cam mechanism1100to move the conduit230crelative to the conduit230b. Moving the top1110from the open position (FIG.12) to the closed position (FIG.13) causes the conduit230cto move from the receded position (circled inFIG.12) in which the conduit230cdoes not interface with the bag235to the extended position (circled inFIG.13) in which the conduit230cdoes interface with the bag235. Thus, the conduit230ccan be movable out of contact with the bag235in response to moving the top1110into the open position (FIG.12). In addition, the conduit230ccan be movable into contact with the bag235in response to movement of the plunger1105. When the conduit230cis contact with the bag235, the conduit230ccan make a substantially airtight seal to a latex membrane1305of the bag235. As a result, the conduit230ccan create a path (e.g., the continuous flow path222through the conduits230a,230b,230c) for the debris215and the air to pass between the debris bin210and the bag235. In some cases, the canister can include alignment features, such as slots1112, that align the bag235with the bag interface end1210of the conduit230c.

The mechanisms of the top1110and the conduit230cmay provide the user a convenient way to load the bag235in the evacuation station205, and to remove the bag from the evacuation station. Before the bag235is placed into the canister220, the user can open the top1110(FIG.12), causing the conduit230cto move into the receded position (FIG.12). The user can then place the bag235into the canister220such that the bag235is aligned with the conduit230c. The user can close the top1110(FIG.13), causing the conduit230cto move into the extended position (FIG.13). The bag interface end1210of the conduit230ccan connect with the bag235, thus interfacing the bag235with the conduit230c. Thus, the user can incorporate the bag235into the flow path222without significantly manually manipulating the bag235and the bag interface end1210of the conduit230c.

As described herein, while the debris215is trapped within the bag235, air continues flowing through the bag235into the exhaust chamber236. As shown inFIG.14, the exhaust chamber236includes a motor housing1400that houses the motor218(not shown inFIG.14). Thus, the air exiting through the exit port223carries energy associated with noise of the motor218.

The exhaust chamber236can include features to reduce or decrease the amount of noise caused by the motor218. As shown inFIG.14, in the exhaust chamber236of the canister220, the air takes two split flow paths1405aand1405bout through the exit port223. The split flow paths1405a,1405bexit through a portion1407of the motor housing1400. The portion1407faces away from the exit port223to extend the distance that air travels between the motor218and the exit port223. In some cases, the canister220further includes foam insulation1410adjacent the split flow paths1405a,1405bthat absorb sound as the air travels along the split flow paths1405a,1405b. The split flow path1405a,1405band the foam insulation1410can together reduce the noise caused by the motor218.

The evacuation station205can include additional features that affect evacuation operation of the evacuation station205. In an example, the ramp907, as shown inFIG.3andFIG.15, assists with guiding debris215towards the intake port227. The ramp907forms an angle1502with a surface1505on which the evacuation station205rests. Thus, the ramp907increases in height relative to the surface1505. The angle1502allows gravity to cause debris215residing in the debris bin210to gather at toward the back of the debris bin210closer to the exhaust port225of the debris bin210when the mobile robot200docks at the evacuation station205. During evacuation, as the negative air pressure loosens and suctions the debris215, gravity also assists in moving the debris215toward the exhaust port225into the flow path222. Thus, the angle of the ramp907can expedite the evacuation operation.

In some examples, the evacuation station205can include features to assist in proper alignment and positioning of the mobile robot200relative to the evacuation station205. For horizontal alignment (e.g., alignment along a y-axis1506Y shown inFIG.3) of the mobile robot200with the evacuation station205, the ramp907can include wheel ramps1510(shown inFIG.3) that are sized and shaped appropriately to receive wheels of the mobile robot200. When the mobile robot200navigates up the ramp907, the wheels of the mobile robot200align with the wheel ramps1510. The wheel ramps1510can include traction features1520(shown inFIG.3) that can increase traction between the mobile robot200and the ramp907so that the mobile robot200can navigate up the ramp907and dock at the evacuation station205.

For vertical alignment (e.g., alignment along a z-axis1506Z shown inFIG.3), the evacuation station205can include, as shown inFIG.15, a robot stabilization protrusion1525on the mobile robot200that contacts a robot stabilization protrusion1530on the ramp907. When the mobile robot200docks at the evacuation station205, the robot stabilization protrusions1525,1530thus can maintain contact between the electrical contacts240of the mobile robot200with the electrical contacts245of the evacuation station205. The robot stabilization protrusion1530on the ramp907is located between a surface1532on the ramp907and the underside805of the mobile robot200. In some implementations, the ramp907can include two or more robot stabilization protrusions1530and/or two or more robot stabilization protrusions1525.

During the evacuation operation, the negative air pressure results in a force applied to a rear portion1531of the mobile robot200. The force can cause motion of portions of the mobile robot200along the z-axis1506Z. For example, a frontward portion (not shown inFIG.15) may lift off of the ramp907, thus potentially resulting in misalignment between the electrical contacts240and the electrical contacts245. Contact between the robot stabilization protrusion1525and the robot stabilization protrusion1530can reduce motion of the mobile robot200caused by the force resulting from negative air pressure that can cause the mobile robot200to lift off of the ramp907. As a result, the electrical contacts240can remain in contact with the electrical contacts245so that the evacuation operation continues uninterrupted.

The evacuation stations (e.g., the evacuation station205) described herein can be used with a number of types of mobile robots that include bins to store debris. The evacuation stations can evacuate the debris from the bins.

In an example, as shown inFIG.16, a mobile robot1600can be a robotic vacuum cleaner that ingests debris from a floor surface. The mobile robot1600includes a body1602that navigates about a floor surface1603using drive wheels1604. A caster wheel1605and the drive wheels1604support the body1602over the floor surface1603. The drive wheels1604and the caster wheel1605can support the body1602, and hence a debris bin1612(e.g., the debris bin210), such that the debris bin1612is supported a clearance distance1611between 3 and 15 mm above the surface1603.

The mobile robot1600ingests debris1610(e.g., the debris215) using a suction mechanism1606to generate an air flow1608that causes the debris1610on the floor surface1603to be propelled into the debris bin1612. The suction mechanism1606can thus suction debris1610from the floor surface1603into the debris bin1612during traversal of the floor surface1603. The body1602supports a front roller1614aand a rear roller1614bthat cooperate to retrieve debris1610from the surface1603. More particularly, the rear roller1614brotates in a counterclockwise sense CC, and the front roller1614arotates in a clockwise sense C. As the front roller1614aand the rear roller1614brotate, the mobile robot1600ingests the debris and the air flow1608causes the debris1610to flow into the debris bin1612. The debris bin1612includes a chamber1613to hold the debris1610received by the mobile robot1600.

A control system1615(implemented, e.g., by one or more processing devices) can control operation of the mobile robot1600as the mobile robot1600traverses the floor surface1603. For example, during a cleaning operation, the control system1615can cause motors (not shown) to rotate the drive wheels1604to cause the mobile robot1600to move across the floor surface1603. The control system1615, during the cleaning operation, can further activate motors to cause rotation of the front roller1614aand the rear roller1614band to activate the suction mechanism1606to retrieve the debris1610from the floor surface1603.

The debris bin1612provides an interface between the chamber1613and an evacuation station (e.g., the evacuation station205) such that the evacuation station can evacuate the debris1610stored in the chamber1613and the debris bin1612. The debris bin1612includes an exhaust port1616(e.g., the exhaust port225) through which debris1610can exit the chamber1613of the debris bin1612into the evacuation station.

InFIGS.17to18, a bin door1701is open so that an evacuation door unit1700is visible. During the cleaning operation and the evacuation operation, the bin door1701is typically closed. The user can open the bin door1701by rotating the bin door1701about hinges1706to manually empty debris1610from the debris bin1612.

As shown inFIGS.17and18, the evacuation door unit1700of the debris bin1612can include a flap (also referred to as a door)1705that opens and closes to control flow of the debris1610between the chamber1613and external devices. The door unit1700includes a support structure1702disposed within the debris bin1612. The support structure1702can be semi-spherical. The door unit1700is located over the exhaust port1616. The flap1705is configured to move between a closed position shown inFIG.17and an open position shown inFIG.18. The flap1705is mounted on the support structure1702. The flap1705moves from the closed position to the open position in response to a difference in air pressure at the exhaust port and within the debris bin1612. As described herein, the evacuation station can generate a negative air pressure, thus causing the air in the debris bin1612to generate an air pressure that moves the flap1705from the closed position (FIG.17) to the open position (FIG.18). In the closed position (FIG.17), the flap1705blocks air flow between the debris bin1612and the environment. In the open position (FIG.18), the flap1705provides a path1800between the debris bin1612and the exhaust port1616.

The door unit1700can include a biasing mechanism that biases the flap1705into the closed position (FIG.17). In an example, as shown inFIG.19A, which depicts an underside of the door unit1700, a torsion spring1900biases the flap1705into the closed position (FIG.17). The flap1705rotates about a hinge1902having a rotational axis1905, and the torsion spring1900applies force that generates a torque about the axis1905that biases the flap1705into the closed position (FIG.17). The hinge1902connects the flap1705to the support structure1702of the door unit1700.

In another example, as shown inFIG.19B, which depicts the underside of the door unit1700, andFIG.21B, which depicts a top perspective view of the door unit1700within the debris bin1612, a leaf spring1910biases the flap1705into the closed position. The flap1705rotates about a flexible coupler1912that has an approximate rotational axis, and the leaf spring1910applies force that generates a torque about the rotational axis that biases the flap into the closed position. The flexible coupler1912acts like a hinge which does not have any relative rotation of parts at a mechanical interface, like a mechanical hinge.

In another example, as shown inFIGS.19C and19Dwhich depicts a cross-sectional view of the door unit1700and a relaxing spring1920of the door unit1700that biases the flap1705into the closed position. In this example, the spring force that holds the flap1705shut relaxes as the flap1705opens. Because the spring force relaxes as the flap1705opens, the magnitude of the pressure wave that the debris bin sees during evacuation is determined by the cracking pressure on the flap1705. The amount of material evacuated is affected by how wide the flap1705opens. With flow, after the flap1705opens, the pressure drops. The relaxing spring1920is believed to provide a spring with a high crack force but a low dwell force. The flap1705is designed to be closed by a sliding interaction between the spring1920and a lever arm1925as the flap1705opens, the contact point slides up and shortens the lever arm1925between the spring1920and a flap pivot1930and thus reduces the moment on the flap1705. As a result, a smaller force on the flap1705(e.g., from pressure) is required to maintain the flap1705open. In some examples, the sliding could be aided by a roller on the flap1705along the lever arm1925to reduce sliding friction.

During the evacuation operation, the air pressure generated against the flap1705causes the flap1705to overcome the biasing force exerted by the biasing mechanism (e.g., the torsion spring1900, the leaf spring1910, the relaxing spring1920), thus causing the flap1705to move from the closed position (FIG.17) to the open position (FIG.18).

During the cleaning operation, the flap1705of the door unit1700closes the exhaust port1616such that the debris1610cannot escape through the exhaust port1616. As a result, the debris1610ingested into the debris bin1612remains in the chamber1613. During an evacuation operation as described herein, air pressure causes the flap1705of the door unit1700to open, thereby exposing the exhaust port1616such that the debris1610in the chamber1613can exit through the exhaust port1616into the evacuation station.

FIGS.20to22depict the flap1705in the closed position.FIGS.23,24, and25show the same perspectives of the door unit1700, asFIGS.20,21A, and22, respectively, but the flap1705is in the open position. A biasing mechanism2030(e.g., a biasing mechanism that includes the torsion spring1900ofFIG.19A, the leaf spring1910ofFIG.19B, or the relaxing spring1920ofFIGS.19C and19D), biases the flap1705into the closed position (FIGS.20to22). As described herein, the negative air pressure causes the flap1705to move into the open position (FIGS.23to25). The flap1705in the open position (FIGS.23to25) forms the path1800, which allows air and thus the debris1610to flow through the exhaust port1616into the evacuation station.

The flap1705in the closed position inFIG.22and in the open position inFIG.25remain within an exterior surface2200(e.g., a bottom surface) of the debris bin1610. Thus, the flap1705cannot inadvertently contact objects outside of the debris bin1610, such as the floor surface1603about which the mobile robot1600moves. In some cases, the flap1705, at a full extension toward the exterior surface2200when the flap1705is in the open position (FIG.25), the flap1705is above the exterior surface2200by a distance between 0 and 10 mm. In some implementations, the flap1705may extend past the exterior surface2200. In such cases, to prevent the flap1705from contacting the floor surface (e.g., the surface1603ofFIG.16), the flap1705can extend a distance less than the clearance distance1611.

The biasing mechanism2030(e.g., which can include the torsion spring1900, the leaf spring1910, or the relaxing spring1920) can have a nonlinear response to the air pressure at the exhaust port1616. For example, as the flap1705moves from the closed position to the open position, the torque generated by the biasing mechanism2030can decrease because a lever arm about the axis1905for the biasing force of the biasing mechanism2030decreases. Thus, the biasing mechanism2030can require a first air pressure to move initially from the closed position (FIGS.20to22) to the open position (FIGS.23to25) that is higher than a second air pressure to maintain the door in the open position (FIGS.23to25). The first air pressure can be 0% to 100% greater than the second air pressure, depending on conditions in the environment and the composition of the debris.

The door unit1700can be positioned to increase the speed at which debris1610can be evacuated from the debris bin1612. ReferringFIG.20, which shows the flap1705in the closed position (e.g., as shown inFIG.17), the door unit1700is located on a half2000of a full length2002of the debris bin1612. The door unit1700is located opposite to the suctioning mechanism1606that occupies a half2005of the full length2002. The door unit1700is located adjacent a corner2010of the debris bin1612such that the door unit1700is within a distance of 0% to 25% of the full length2002of the debris bin1612to the corner2010. The door unit1700can be partially located within a rearward portion2007of the debris bin1612. The flap1705faces outwardly towards the debris bin1612from the corner2010such that debris1610from a large portion of the debris bin1612is directed toward the path1800provided by the flap1705in the open position (FIGS.23to25). As a result, when the flap1705is in the open position (FIGS.23to25) and the evacuation station has initiated the evacuation operation, the negative air pressure can cause debris1610from difficult-to-reach locations throughout the debris bin1612—including, for example, corners and areas in the rearward portion2007—to flow into the path1800to be evacuated into the evacuation station.

In an example, the full length2002of the debris bin1612is between 20 and 50 centimeters. The debris bin can have a width2015between 10 and 20 centimeters. The door unit1700is located between 0 to 8 centimeters from the corner2010(e.g., a horizontal distance between 0 and 8 centimeters, a vertical distance between 0 and 8 centimeters). The door unit1700can have a diameter between 2 centimeters and 6 centimeters.

As shown inFIGS.21A,21B, and22, the flap1705can be made of a solid plastic or other rigid material and can be concavely curved relative to, the support structure1702. Thus, air pressure within the debris bin1612on the flap1705during the evacuation operation can result in greater forces on the flap1705to cause the flap1705to more easily move from the open position (FIGS.20to22) to the closed position (FIGS.23to25).

A stretchable material2100can cover part of the flap1705such that debris1610entering through the path1800when the flap1705is open (FIGS.23to25) does become lodged between the flap1705and the support structure1702. The stretchable material2100can be formed of a resilient material, such as an elastomer. In some implementations, the stretchable material2100can be formed of ethylene propylene diene monomer (EPDM) rubber, silicone rubber, polyether block amides, Chloropene rubber, Butyl rubber, among other elastomeric materials. As shown inFIG.21A, the stretchable material2100can cover an intersection2105(shown inFIG.21A) of the flap1705and the support structure1702. Debris1610and other foreign material along the intersection2105can prevent the flap1705from closing and forming a seal with the support structure1702. Thus, the stretchable material2100prevents debris1610from gathering at the intersection2105so that the debris1610does not interfere with proper functionality of the flap1705of the door unit1700. In some implementations, the hinge and stretchable material could be replaced with a flexible coupler (e.g., as described with respect toFIG.19B) made of similar stretchable materials to perform the same function. In such implementations, the flap1705is attached to the support structure1702by the flexible coupler.

An adhesive can be used to adhere the stretchable material2100to the flap1705and to the support structure1702. The stretchable material2100can be adhered to the flap1705along a fixed portion2110and can be adhered to the support structure1702along a fixed portion2120. The adhesive can be absent at a location2130of or above the hinge (e.g., the hinge1902) about which the flap1705. The adhesive can further be absent at the intersection2105of the flap1705and the support structure1702. Thus, the stretchable material2100can flex and deform along the location2130while the fixed portions2110,2120of the stretchable material2100remain fixed to the flap1705and the support structure1702, respectively, and do not flex. The absence of adhesive along the location2130provides a flexible portion for the stretchable material2100so that the stretchable material2100does not break or fracture due to excessive stress caused by the movement of the flap1705from the closed position (FIGS.20to22) to the open position (FIGS.23to25).

During the cleaning operation, the flap1705biased into the closed position (FIGS.20to22) due to the biasing mechanism2030prevents the debris1610from exiting the debris bin1612through the exhaust port1616. During an evacuation operation, the mobile robot200docks at the evacuation station so that the evacuation station can generate negative air pressure to evacuate the debris1610. The debris1610can flow through the exhaust port1616with air flow generated during the evacuation operation. The flap1705, forced into the open position (FIGS.23to25) due to the negative air pressure generated during the evacuation operation, provides the path1800so that the debris1610can travel along a flow path (e.g., flow path222) to a bag (e.g., bag235) of the evacuation station. As the debris flow through the exhaust port1616, the stretchable material2100further prevents the debris1610from gathering around the biasing mechanism2030and at the intersection2105. Thus, after the evacuation operation, the biasing mechanism2030can easily bias the flap1705into the closed position (FIGS.20to22), and the mobile robot200can continue the cleaning operation and continue ingesting debris1610and storing debris1610in the debris bin1612.

The robots described herein can be controlled, at least in part, using one or more computer program products, e.g., one or more computer programs tangibly embodied in one or more information carriers, such as one or more non-transitory machine-readable media, for execution by, or to control the operation of, one or more data processing apparatus, e.g., a programmable processor, a computer, multiple computers, and/or programmable logic components.

A computer program can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.

Operations associated with controlling the robots described herein can be performed by one or more programmable processors executing one or more computer programs to perform the functions described herein. Control over all or part of the robots and evacuation stations described herein can be implemented using special purpose logic circuitry, e.g., an FPGA (field programmable gate array) and/or an ASIC (application-specific integrated circuit).

Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only storage area or a random access storage area or both. Elements of a computer include one or more processors for executing instructions and one or more storage area devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from, or transfer data to, or both, one or more machine-readable storage media, such as mass PCBs for storing data, e.g., magnetic, magneto-optical disks, or optical disks. Machine-readable storage media suitable for embodying computer program instructions and data include all forms of non-volatile storage area, including by way of example, semiconductor storage area devices, e.g., EPROM, EEPROM, and flash storage area devices; magnetic disks, e.g., internal hard disks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks.

Elements of different implementations described herein may be combined to form other embodiments not specifically set forth above. Elements may be left out of the structures described herein without adversely affecting their operation. Furthermore, various separate elements may be combined into one or more individual elements to perform the functions described herein.