AU2021303009B2 - Robot vacuum and robot vacuum control method - Google Patents

Abstract

The present invention relates to a robot vacuum that travels along a virtual traveling line connecting, in a straight line, a starting point and a predetermined target point, and comprises: a body in which a space for accommodating a battery, a water tank and a motor is formed; and a pair of rotating plates of which mops facing a floor surface are coupled to lower sides thereof, and which are rotatably disposed on the bottom surface of the body, wherein, with respect to the pair of rotating plates, the rotational speed of the rotating plate positioned far away from the traveling line is greater than the rotational speed of the rotating plate positioned close to the traveling line.

Description

ROBOT CLEANER AND METHOD OF CONTROLLING THE SAME

[Field]

The present disclosure relates to a robot cleaner and a method of controlling the

same, and more particularly, to a robot cleaner that rotates a mopping cloth thereof and is

capable of traveling and cleaning the floor through a frictional force between the mopping

cloth and the floor, and a method of controlling the robot cleaner.

[Background]

With the recent development of industrial technology, robot cleaners have been

developed which clean, while traveling, a cleaning-required zone autonomously without

user's manipulation. The robot cleaner includes a sensor capable of recognizing a space

to be cleaned, a mopping cloth capable of cleaning the floor surface, etc., and travels

while wiping the floor surface of the space recognized by the sensor with the mopping

cloth, etc.

Among the robot cleaners, a wet robot cleaner is capable of wiping the floor

surface with a mopping cloth containing moisture to effectively remove a foreign material

strongly attached to the floor surface. The wet robot cleaner includes a water container,

and water contained in the water container is supplied to the mopping cloth such that the

mopping cloth containing moisture wipes the floor surface to effectively remove the

foreign material strongly attached to the floor surface.

The wet robot cleaner may be structured such that the mopping cloth is formed

in a circular form and contacts the floor surface while rotating to wipe the floor surface.

In addition, the robot cleaner may travel in a particular direction by using a frictional

force generated by contact of a plurality of mopping cloths with the floor surface during

rotation.

Meanwhile, as the mopping cloth may more strongly wipe the floor surface with a greater frictional force between the mopping cloth and the floor surface, the robot cleaner may effectively clean the floor surface.

Meanwhile, as a pair of mopping cloths rotate in different directions at the same

rotation speed, the wet robot cleaner travels straight.

However, when compared to a robot cleaner capable of traveling straight through

rotation of wheels, in the wet robot cleaner, the frictional force between the mopping cloth

and the floor surface is not often constant.

As a result, the robot cleaner often slips, having a difficulty in traveling straight

to a target point.

Meanwhile, Korean patent registration No. 10-1970995B1 (April 16, 2019)

discloses a robot cleaner for traveling straight and a control method thereof.

Load values of a first rotation member and a second rotation member are

respectively calculated, a load difference is calculated using the calculated load values,

and when the calculated difference is greater than a set value, a rotation speed of at least

one of the first rotation member or the second rotation member is adjusted, thereby

causing the robot cleaner to travel straight.

However, when load values of one pair of rotation members are compared for

control in this way, the robot cleaner simply resumes straight traveling at that position

and is not capable of traveling to return to a straight path toward a target point.

Meanwhile, Korean patent registration no. 10-1903022B1 (September 20, 2018)

discloses a robot cleaner which travels straight by rotating a pair of spin mops.

In this case, between the pair of spin mops, the left spin mop rotates clockwise

and the right spin mop rotates counterclockwise, thus causing the robot cleaner to move

straight.

However, when one pair of spin mops rotate in different directions as such, frictional forces between the respective spin mops and the floor surface may be different from each other in many cases, depending on a condition (non-uniformity) of the floor surface or a difference in contamination level or moisture content between the spin mops of the pair.

As a result, even when the robot cleaner rotates the pair of spin mops in different

directions and at the same speed, the actual moving path of the robot cleaner may deviate

from a straight path.

Korean patent registration No. 10-1412143B1 (June 19, 2014) discloses a robot

cleaner that controls the amount of rotation of a driving wheel by detecting a rotation

angle of a caster wheel for straight traveling, and a method for controlling traveling of the

robot cleaner.

However, the foregoing robot cleaner needs to include a separate rotatable caster

wheel and a separate sensor capable of detecting a rotation angle of the caster wheel.

Moreover, the robot cleaner simply performs correction for straight traveling, failing in

guaranteeing accurate movement to a target point.

One or more embodiments of the present disclosure address or ameliorate at least

one disadvantage or shortcoming of prior techniques, or at least provide a useful

alternative thereto.

Any discussion of documents, acts, materials, devices, articles or the like which

has been included in the present specification is not to be taken as an admission that any

or all of these matters form part of the prior art base or were common general knowledge

in the field relevant to the present disclosure as it existed before the priority date of each

of the appended claims.

The present disclosure has been conceived to improve the foregoing problems of

conventional robot cleaners and control methods of the same, and provides a robot cleaner and a method of controlling the same, whereby when the robot cleaner deviates from a straight path due to slippage between a mopping cloth and a floor surface, the deviation may be compensated for.

Moreover, the present disclosure provides a robot cleaner and a method of

controlling the same, whereby the robot cleaner may quickly determine deviation thereof

from a straight path and change a direction thereof to return to the straight path.

In addition, the present disclosure provides a robot cleaner and a method of

controlling the same, whereby it is possible to prevent the robot cleaner from wandering

due to a failure to find a traveling direction, after deviating from a straight path.

Furthermore, the present disclosure provides a robot cleaner and a method of

controlling the same, whereby even when the robot cleaner deviates from a straight path,

the robot cleaner may find and move to a target point.

The present disclosure also provides a robot cleaner and a method of controlling

the same, whereby the robot cleaner returns to a straight path while continuously traveling,

thus maintaining cleaning performance for an area to be cleaned.

[Summary]

Some embodiments of the present disclosure relate to a robot cleaner that travels

along a virtual traveling line connecting a start point to a predetermined target point in a

straight line includes a body having formed therein a space for accommodating a battery,

a water container, and a motor, and a pair of rotation plates that have coupled to lower

sides thereof, mopping cloths facing a floor surface, and are rotatably disposed on a

bottom surface of the body.

When a shortest distance between the body and the traveling line is greater than

or equal to a predetermined reference distance, rotation speeds of the pair of rotation

plates may be different from each other to approach the traveling line.

The pair of rotation plates may be such that the rotation speed of the rotation plate

located far from the traveling line is higher than the rotation speed of the rotation plate

located close to the traveling line.

The pair of rotation plates may be such that when the shortest distance between

the body and the traveling line decreases, the rotation speed of the rotation plate located

close to the traveling line is increased.

The pair of rotation plates may include a first rotation plate that has coupled to a

lower side thereof a first mopping cloth facing the floor surface and is rotatably disposed

on the bottom surface of the body and a second rotation plate that has coupled to a lower

side thereof a second mopping cloth facing the floor surface and is rotatably disposed on

the bottom surface of the body.

When a midpoint between a rotation axis of the first rotation plate and a rotation

axis of the second rotation plate is located on the traveling line after the first mopping

cloth passes through the traveling line, the rotation speed of the first rotation plate may

be higher than the rotation speed of the second rotation plate.

The robot cleaner according to the present disclosure may further include a

virtual connection line connecting rotation axes of the pair of rotation plates to each other

and a virtual traveling direction line perpendicularly intersecting the connection line at

the midpoint of the connection line and extending in parallel to the floor surface.

The traveling direction line may include a forward traveling direction line

extending in parallel to the floor surface toward a direction in which the battery is

disposed with respect to the connection line and a backward traveling direction line

extending in parallel to the floor surface toward a direction in which the water container

is disposed with respect to the connection line.

The body may rotate such that the forward traveling direction line and the traveling line intersect each other, when an angle formed by intersection between the backward traveling direction line and the traveling line is greater than or equal to a predetermined reference angle.

The pair of rotation plates may be such that the rotation speed of the rotation plate

located far from the traveling line is higher than the rotation speed of the rotation plate

located close to the traveling line, when the angle formed by intersection between the

backward traveling direction line and the traveling line is greater than or equal to the

predetermined reference angle.

The robot cleaner according to the present disclosure may further include a

virtual movement point located on the traveling line and disposed at a shortest distance

to the midpoint of the connection line and a virtual target intersection point located on the

traveling line and disposed at a predetermined distance from the movement point toward

the target point.

The target intersection point may be a point at which the traveling line and the

forward traveling direction line intersect each other.

The pair of rotation plates may be such that the rotation speed of the rotation plate

located far from the target intersection point is higher than the rotation speed of the

rotation plate located close to the target intersection point.

A relative movement speed of a mopping cloth located far from the traveling line

with respect to the floor surface may be higher than a relative movement speed of a

mopping cloth located close to the traveling line with respect to the floor surface.

An output of a motor located far from the traveling line may be greater than an

output of a motor located close to the traveling line.

Some embodiments of the present disclosure relate to a method of controlling a

robot cleaner that includes a pair of rotation plates having coupled to lower sides thereof, mopping cloths facing a floor surface, and travels by rotating the pair of rotation plates includes a straight traveling operation of causing the robot cleaner to travel straight along a virtual traveling line connecting a start point to a predetermined target point in a straight line and a straight-traveling correction operation of rotating a body of the robot cleaner to approach the traveling line by changing the rotation speed of rotation plates when the robot cleaner deviates from the traveling line.

In the straight traveling operation, the pair of rotation plates may be rotated at a

same speed.

In the straight traveling operation, rotation directions of the pair of rotation plates

may be opposite to each other.

The straight-traveling correction operation may include a first correction

operation of rotating a rotation plate located far from the traveling line faster than a

rotation plate located close to the traveling line.

The straight-traveling correction operation may further include a second

correction operation of increasing the rotation speed of the rotation plate located close to

the traveling line between the pair of rotation plates, after the first correction operation.

In the straight-traveling correction operation, a virtual movement point disposed

at a shortest distance from the robot cleaner may be generated on the traveling line, a

target intersection point may be generated at a predetermined distance from the movement

point to the target point, and the robot cleaner may be caused to travel toward the target

intersection point.

In the first correction operation, as a shortest distance between the traveling line

and the body of the robot cleaner increases, a rotation angle of the body of the robot

cleaner may increase.

In the first correction operation, as a change per time of the shortest distance between the traveling line and the body of the robot cleaner increases, the rotation angle of the body of the robot cleaner may increase.

In the first correction operation, as a distance difference between a front end of

the robot cleaner and a rear end of the robot cleaner with respect to the traveling line

increases, the rotation speed of the rotation plate located far from the traveling line

between the pair of rotation plates may be increased.

In the first correction operation, as a change per time of the distance difference

between the front end of the robot cleaner and the rear end of the robot cleaner with

respect to the traveling line increases, the rotation speed of the rotation plate located far

from the traveling line may be increased.

In the second correction operation, the rotation speed of the rotation plate located

close to the traveling line may be increased as the shortest distance between the traveling

line and the body of the robot cleaner decreases.

In second correction operation, a weight value may be applied to

increase/reduction of the rotation speeds of the pair of rotation plates according to a

distance between the traveling line and the robot cleaner.

The method may further include a deviation determination operation of

determining whether the robot cleaner deviates from a virtual traveling line that connects

the start point to the target point in a straight line.

In the deviation determination operation, it may be determined that the robot

cleaner deviates from the traveling line, when the shortest distance between the traveling

line and the front end of the robot cleaner is greater than or equal to a predetermined

reference distance.

In the deviation determination operation, it may be determined that the robot

cleaner deviates from the traveling line, when the shortest distance between the traveling line and the front end of the robot cleaner is greater than or equal to a predetermined reference distance.

As described above, with a robot cleaner and a method of controlling the same

according to the present disclosure, when the robot cleaner deviates from a straight path

due to slippage between a mopping cloth and a floor surface, a rotation speed of a rotation

plate located far from the straight path is higher than that of a rotation plate located close

to the straight path, such that the robot cleaner may turn to the straight path, thereby

compensating for a deviating distance.

Moreover, with the robot cleaner and the method of controlling the same

according to the present disclosure, it is possible to quickly determine whether the robot

cleaner deviates from the straight path, based on a predetermined reference distance or a

predetermined reference angle, and thus the robot cleaner may return to the straight path

by changing the direction thereof.

Furthermore, even after the robot cleaner deviates from the straight path, the

traveling direction of the robot cleaner is determined and the robot cleaner is caused to

move, thereby preventing the robot cleaner from wandering due to a failure to find the

traveling direction.

In addition, even when the robot cleaner deviates from the straight path, the robot

cleaner may return to the straight path and gradually move to a final target point.

The robot cleaner also returns to the straight path while continuously traveling,

thereby maintaining cleaning performance for an area to be cleaned.

[Description of Drawings]

FIG. IA is a perspective view of a robot cleaner according to an embodiment of

the present disclosure;

FIG. lB is a view of some components separated from the robot cleaner shown in FIG. IA;

FIG. IC is a rear view of the robot cleaner shown in FIG. IA;

FIG. ID is a bottom view of a robot cleaner according to an embodiment of the

present disclosure;

FIG. IE is an exploded perspective view of a robot cleaner according to an

embodiment of the present disclosure;

FIG. IF is a cross-sectional view schematically showing a robot cleaner and

components thereof, according to an embodiment of the present disclosure;

FIG. 2 is a schematic view of a robot cleaner, viewed from top, according to an

embodiment of the present disclosure;

FIG. 3 is a block diagram of a robot cleaner according to an embodiment of the

present disclosure;

FIG. 4 is a flowchart of a method of controlling a robot cleaner, according to an

embodiment of the present disclosure;

FIGS. 5 through 9 are views for roughly describing a path in which a robot

cleaner travels based on the method of controlling the robot cleaner according to an

embodiment of the present disclosure;

FIG. 10 is a flowchart of a method of controlling a robot cleaner, according to

another embodiment of the present disclosure; and

FIGS. 11 through 14 are views for roughly describing a path in which a robot

cleaner travels based on the method of controlling the robot cleaner according to another

embodiment of the present disclosure.

[Mode for Invention]

Hereinafter, embodiments of the present disclosure will be described with

reference to the accompanying drawings.

Various changes may be made to the present disclosure and the present disclosure

may have various embodiments which will be described in detail with reference to the

drawings. Such a description is not intended to limit the present disclosure to specified

embodiments, and is construed as including all changes, equivalents, or substitutes

included in the spirit and technical scope of the present disclosure.

To describe the present disclosure, terms such as first, second, and the like may

be used to describe various components, but the components may not be limited to those

terms. These terms may be used merely for the purpose of distinguishing one component

from another component. For example, a first component may be named as a second

component without departing from the right scope of the present disclosure, and similarly,

the second component may be named as the first component.

The term "and/or" used herein includes any and all combinations of one or more

of a plurality of associated listed items.

When a component is referred to as being "connected" or "accessed" to or by any

other component, it should be understood that the component may be directly connected

or accessed by the other component, but another new component may also be interposed

between them. Contrarily, when a component is referred to as being "directly connected"

or "directly accessed" to or by any other component, it should be understood that there is

no component between the component and the other component.

The terms used in the present application are for the purpose of describing

particular exemplary embodiments only and are not intended to be limiting. It is to be

understood that the singular forms include plural references unless the context clearly

dictates otherwise.

It will be further understood that the terms "comprises" and/or "has," when used

in this application, specify the presence of a stated feature, number, step, operation, component, element, or combination thereof, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, elements, or combinations thereof.

All of the terms used herein including technical or scientific terms have the same

meanings as those generally understood by an ordinary skilled person in the related art

unless they are defined otherwise. The terms defined in a generally used dictionary may

be interpreted as having meanings that are the same as or similar with the contextual

meanings of the relevant technology and may not be interpreted as having ideal or

exaggerated meanings unless they are clearly defined in the present application.

Moreover, the following embodiments are provided to more fully describe the

present disclosure to those of ordinary skill in the art, and the shapes, sizes, etc., of

components in the drawings may be exaggerated for clear description.

FIGS. IA through IF are structural views for describing a structure of a robot

cleaner 1 controlled by a control device 5 according to the present disclosure, and FIG. 2

is a schematic view of the robot cleaner 1, viewed from top, according to an embodiment

of the present disclosure.

More specifically, FIG. IA is a perspective view of the robot cleaner 1, FIG. lB

is a view of some components separated from the robot cleaner 1, FIG. 1C is a rear view

of the robot cleaner 1, FIG. ID is a bottom view of the robot cleaner 1, FIG. IE is an

exploded perspective view of the robot cleaner 1, and FIG. IF is an internal cross

sectional view of the robot cleaner 1.

Referring to FIGS. iAthrough IF and 2, a descriptionwill be made of a structure

of the robot cleaner 1 according to the present disclosure.

The robot cleaner 1 may be placed on a floor and clean the floor by using a

mopping cloth while moving along a floor surface B. Thus, hereinbelow, a description will be made by setting a top-bottom direction based on a state where the robot cleaner 1 is placed on the floor.

A side to which a first lower sensor 123 to be described later is coupled will be

described as a front side with respect to a first rotation plate 10 and a second rotation plate

20.

A'lowest portion' of each component described in the present disclosure may be

a portion positioned lowest or a portion closest to the floor, when the robot cleaner 1 is

used placed on the floor.

The robot cleaner 1 may include a body 50, the rotation plates 10 and 20, and

mopping cloths 30 and 40. In this case, the rotation plates 10 and 20 may form a pair

including the first rotation plate 10 and the second rotation plate 20, and the mopping

cloths 30 and 40 may include a first mopping cloth 30 and a second mopping cloth 40.

The body 50 may form an overall appearance of the robot cleaner 1 or may be in

a frame form. Respective parts of the robot cleaner 1 may be coupled to the body 50, and

some parts of the robot cleaner 1 may be accommodated inside the body 50. The body 50

may be divided into a lower body 50a and an upper body 50b, and parts of the robot

cleaner 1 including a battery 135, a water container 141, and motors 56 and 57 may be

provided on a space formed by coupling between the lower body 50a and the upper body

50b (see FIG. iE).

The first rotation plate 10 may be rotatably disposed on a bottom surface of the

body 50 and may have the first mopping cloth 30 coupled to a lower side thereof.

The first rotation plate 10 may have a predetermined area and have a form such

as a flat plate, a flat frame, etc. The first rotation plate 10 may be generally horizontally

laid, such that a horizontal width (or diameter) thereof is sufficiently greater than a

vertical height thereof. The first rotation plate 10 coupled to the body 50 may be parallel or inclined to the floor surface B. The first rotation plate 10 may be in a circular plate form, may have a bottom surface that is generally circular, and may be in a rotationally symmetric shape as a whole.

The second rotation plate 20 may be rotatably disposed on the bottom surface of

the body 50, and may have the second mopping cloth 40 coupled to a lower side thereof.

The second rotation plate 20 may have a predetermined area and have a form

such as a flat plate, a flat frame, etc. The second rotation plate 20 may be generally

horizontally laid, such that a horizontal width (or diameter) thereof is sufficiently larger

than a vertical height thereof. The second rotation plate 20 coupled to the body 50 may

be parallel or inclined to the floor surface B. The second rotation plate 20 may be in a

circular plate form, may have a bottom surface that is generally circular, and may be in a

rotationally symmetric shape as a whole.

In the robot cleaner 1, the second rotation plate 20 may be formed identically or

symmetrically to the first rotation plate 10. When the first rotation plate 10 is located in a

left side of the robot cleaner 1, the second rotation plate 20 may be located in a right side

of the robot cleaner 1, and in this case, the first rotation plate 10 and the second rotation

plate 20 may be bilaterally symmetric to each other.

The first mopping cloth 30 may be coupled to the lower side of the first rotation

plate 10 to face the floor surface B.

The first mopping cloth 30 may include a bottom surface having a predetermined

area, which faces the floor, , and may have a flat form. The first mopping cloth 30 may

have such a form that a horizontal width (or diameter) thereof is sufficiently greater than

a vertical height thereof. When the first mopping cloth 30 is coupled to the body 50, the

bottom surface of the first mopping cloth 30 may be parallel or inclined to the floor

surface B.

The bottom surface of the first mopping cloth 30 may be generally circular, and

the first mopping cloth 30 may be in a rotationally symmetric shape as a whole. The first

mopping cloth 30 may be attached to and detached from the bottom surface of the first

rotation plate 10 and may be coupled to the first rotation plate 10 to rotate together with

the first rotation plate 10.

The second mopping cloth 40 may be coupled to the lower side of the second

rotation plate 20 to face the floor surface B.

The second mopping cloth 40 may include a bottom surface having a

predetermined area, which faces the floor, and may have a flat form. The second mopping

cloth 40 may have such a form that a horizontal width (or diameter) thereof is sufficiently

greater than a vertical height thereof. When the second mopping cloth 40 is coupled to

the body 50, the bottom surface of the second mopping cloth 40 may be parallel or

inclined to the floor surface B.

The bottom surface of the second mopping cloth 40 may be generally circular,

and the second mopping cloth 40 may be in a rotationally symmetric shape as a whole.

The second mopping cloth 40 may be attached to and detached from the bottom surface

of the second rotation plate 20 and may be coupled to the second rotation plate 20 to rotate

together with the second rotation plate 20.

When the first rotation plate 10 and the second rotation plate 20 rotate in opposite

directions and at the same speed, the robot cleaner 1 may move in a straight direction and

move forward or backward. For example, when viewed from top, when the first rotation

plate 10 rotates counterclockwise and the second rotation plate 20 rotates clockwise, the

robot cleaner 1 may move forward.

When any one of the first rotation plate 10 and the second rotation plate 20

rotates, the robot cleaner 1 may change a direction and turn.

When the first rotation plate 10 and the second rotation plate 20 have different

rotation speeds or rotate in the same direction, the robot cleaner 1 may move while

changing a direction and may move in a curved direction.

The robot cleaner 1 may further include the first lower sensor 123.

The first lower sensor 123 may be formed in the lower side of the body 50 to

sense a relative distance to the floor surface B. The first lower sensor 123 may be

variously formed within a range in which the first lower sensor 123 is capable of sensing

the relative distance between a point where the first lower sensor 123 is formed and the

floor surface B.

When the relative distance, sensed by the first lower sensor 123, to the floor

surface B (a vertical distance on the floor surface B or a distance in an inclined direction

on the floor surface B) exceeds a predetermined value or a predetermined range, this case

may correspond to a case where the floor surface B is suddenly lowered, such that the

first lower sensor 123 may sense a cliff.

The first lower sensor 123 may include an optical sensor, a light-emitter that

irradiates light, and a light-receiver to which reflected light is incident. The first lower

sensor 123 may include an infrared sensor.

The first lower sensor 123 may be referred to as a cliff sensor.

The robot cleaner 1 may further include a second lower sensor 124 and a third

lower sensor 125.

When a virtual line connecting the center of the first rotation plate 10 with the

center of the second rotation plate 20 in a horizontal direction (a direction parallel to the

floor surface B) is a connection line L , the second lower sensor 124 and the third lower

sensor 125 may be formed in the lower side of the body 50 in the same side as the first

lower sensor 123 with respect to the connection line LI and sense a relative distance to the floor surface B (see FIG. ID).

The third lower sensor 125 may be formed opposite to the second lower sensor

124 with respect to the first lower sensor 123.

Each of the second lower sensor 124 and the third lower sensor 125 may be

variously formed within a range in which they are capable of sensing a relative distance

to the floor surface B. Each of the second lower sensor 124 and the third lower sensor

125 may be formed identically to the first lower sensor 123 except for a position where

each of them is formed.

The robot cleaner 1 may further include the first motor 56, the second motor 57,

the battery 135, the water container 141, and a water supply tube 142.

The first motor 56 may be coupled to the body 50 to rotate the first rotation plate

10. More specifically, the first motor 56 may include an electric motor coupled to the

body 50, and one or more gears may be connected to the first motor 56 to deliver a

rotational force to the first rotation plate 10.

The second motor 57 may be coupled to the body 50 to rotate the second rotation

plate 20. More specifically, the second motor 57 may include an electric motor coupled

to the body 50, and one or more gears may be connected to the second motor 57 to deliver

a rotational force to the second rotation plate 20.

As such, in the robot cleaner 1, the first rotation plate 10 and the first mopping

cloth 30 may rotate by the operation of the first motor 56, and the second rotation plate

20 and the second mopping cloth 40 may rotate by the operation of the second motor 57.

The second motor 57 may be symmetric (bilaterally symmetric) to the first motor

56.

The battery 135 may be coupled to the body 50 to supply power to other

components of the robot cleaner 1. The battery 135 may supply power to the first motor

56 and the second motor 57.

The battery 135 may be charged by an external power source, and to this end, a

charging terminal for charging the battery 135 may be provided in a side of the body 50

or in the battery 135.

In the robot cleaner 1, the battery 135 may be coupled to the body 50.

The water container 141 may be in a container form having an inner space for

storing liquid such as water therein. The water container 141 may be fixedly coupled to

the body 50 or coupled attachably/detachably to/from the body 50.

In the robot cleaner 1, the water supply tube 142 may be in a tube or pipe form

and may be connected to the water container 141 to allow liquid in the water container

141 to flow therethrough. An opposite end of the water supply tube 142, which is

connected to the water container 141, may be positioned in upper sides of the first rotation

plate 10 and the second rotation plate 20, such that the liquid in the water container 141

may be supplied to the first mopping cloth 30 and the second mopping cloth 40.

In the robot cleaner 1, the water supply tube 142 may have a form in which one

pipe is branched into two parts and an end of any one of the parts may be positioned in

the upper side of the first rotation plate 10 and an end of the other part may be positioned

in the upper side of the second rotation plate 20.

The robot cleaner 1 may include a separate water pump 143 for liquid movement

through the water supply tube 142.

The robot cleaner 1 may further include a bumper 58, a first sensor 121, and a

second sensor 122.

The bumper 58 may be coupled along an edge of the body 50 and move relative

to the body 50. For example, the bumper 58 may be coupled to the body 50 to reciprocate

in a direction close to the center of the body 50.

The bumper 58 may be coupled along a part of the edge of the body 50 or the

entire edge of the body 50.

The first sensor 21 may be coupled to the body 50 and sense movement (relative

movement) of the bumper 58 relative to the body 50. The first sensor 121 may be formed

using a microswitch, a photo interrupter, a tact switch, etc.

The second sensor 122 may be coupled to the body 50 and sense a relative

distance to an obstacle. The second sensor 122 may include a distance sensor.

Meanwhile, the robot cleaner 1 according to an embodiment of the present

disclosure may further include a displacement sensor 126.

The displacement sensor 126 may be disposed on the bottom surface (rear

surface) of the body 50 and measure a distance the robot cleaner 1 moves along the floor

surface B.

For example, the displacement sensor 126 may use an optical flow sensor (OFS)

that obtains image information of the floor surface by using light. Herein, the OFS may

include an image sensor that obtains the image information of the floor surface by

capturing an image of the floor surface and one or more light sources that adjust the

amount of light.

An operation of the displacement sensor 126 will be described using the OFS as

an example. The OFS may be provided on the bottom surface (rear surface) of the robot

cleaner I to capture an image in a downward direction, i.e., an image of the floor surface.

The OFS may convert a downward image input from the image sensor to generate

downward image information of a predetermined format.

With this configuration, the displacement sensor 126 may detect a relative

position of the robot cleaner 1 with respect to a predetermined point, regardless of

slippage. That is, by allowing the downward direction of the robot cleaner 1 to be observed using the OFS, position correction corresponding to slippage may be possible.

Meanwhile, the robot cleaner 1 according to an embodiment of the present

disclosure may further include an angle sensor 127.

The angle sensor 127 may be disposed inside the body 50 and measure a

movement angle of the body 50.

For example, the angle sensor 127 may use a gyro sensor that measures a rotation

speed of the body 50. The gyro sensor may detect a direction of the robot cleaner 1 by

using the rotation speed.

With this configuration, the angle sensor 127 may detect an angle of the traveling

direction of the robot cleaner 1 with respect to a predetermined virtual line.

Meanwhile, the present disclosure may further include the virtual connection

line Li that connects rotation axes of one pair of rotation plates 10 and 20 to each other.

More specifically, the connection line LI may mean a virtual line that connects the

rotation axis of the first rotation plate 10 to the rotation axis of the second rotation plate

20.

The connection line LI may be a reference that divides the robot cleaner 1 into

a front and a rear. For example, a direction in which the first lower sensor 123 is disposed

with respect to the connection line Li may be referred to as the front of the robot cleaner

1 and a direction in which the water container 141 is disposed with respect to the

connection line Limay be referred to as the rear of the robot cleaner 1.

Thus, the first lower sensor 123, the second lower sensor 124, and the third lower

sensor 125 may be disposed in a front lower side of the body 50 with respect to the

connection line LI, the first sensor 121 may be disposed in an inner side of a front outer

circumferential surface of the body 50, and the second sensor 122 may be disposed in a

front upper side of the body 50. The battery 135 may be insertedly coupled to the front of the body 50 with respect to the connection line Li in a direction perpendicular to the floor surface B. The displacement sensor 126 may be disposed in the rear of the body 50 with respect to the connection line Ll.

Meanwhile, the present disclosure may further include a virtual traveling

direction line H that perpendicularly intersects with the connection line Li at a midpoint

C of the connection line LI and extends in parallel to the floor surface B. More

specifically, the traveling direction line H may include a forward traveling direction line

Hf that extends in parallel to the floor surface B toward a direction in which the battery

135 is disposed with respect to the connection line L and a backward traveling direction

line Hb that extends in parallel to the floor surface B toward a direction in which the water

container 141 is disposed with respect to the connection line LI. The battery 135 and the

first lower sensor 123 may be disposed on the forward traveling direction line Hf, and the

displacement sensor 126 and the water container 141 may be disposed on the backward

traveling direction line Hb. The first rotation plate 10 and the second rotation plate 20

may be disposed symmetric (line-symmetric) to each other around (with respect to) the

traveling direction line H.

With this configuration, the traveling direction line H may mean a direction in

which the robot cleaner 1 travels.

Meanwhile, to help understanding, the front end of the robot cleaner 1 according

to the present disclosure will be described as below. The front end of the robot cleaner 1

in the present disclosure may mean the farthest point protruding forward along the

horizontal direction with respect to the connection line Ll. For example, the front end of

the robot cleaner 1 may mean a point through which the forward traveling direction line

Hf passes on an outer circumferential surface of the bumper 58.

A rear end of the robot cleaner 1 may mean the farthest point protruding backward along the horizontal direction with respect to the connection line Ll. For example, the rear end of the robot cleaner 1 may mean a point through which the backward traveling direction line Hb passes on an outer circumferential surface of the water container 141.

Meanwhile, a block diagram of the robot cleaner 1 shown in FIG. 1 of the present

disclosure is shown in FIG. 3.

Referring to FIG. 3, the robot cleaner 1 may include a controller 110, a sensor

unit 120, a power source unit 130, a water supply unit 140, a driving unit 150, a

communication unit 160, a display unit 170, and memory 180. The components shown in

the block diagram of FIG. 2 are not essential to implement the robot cleaner 1, and the

robot cleaner 1 described herein may include components that are more or less than the

above-described components.

The controller 110 may be disposed inside the body 50, and may be connected

to a control device (not shown) by wireless communication through the communication

unit 160 to be described later. In this case, the controller 110 may transmit various data

regarding the robot cleaner 1 to the connected control device (not shown). The controller

110 may receive input data from the connected control device and store the same. Herein,

the data input from the control device may be a control signal for controlling at least one

function of the robot cleaner 1.

That is, the robot cleaner 1 may receive a control signal based on a user input

from the control device and operate according to the received control signal.

The controller 110 may control overall operations of the robot cleaner 1. The

controller 110 may control the robot cleaner 1 to perform a cleaning operation while

autonomously traveling on a cleaning surface to be cleaned, based on configuration

information stored in the memory 180 to be described later.

Meanwhile, straight-traveling control of the controller 110 will be described later

in the present disclosure.

The sensor unit 120 may include one or more of the first lower sensor 123, the

second lower sensor 124, the third lower sensor 125, the first sensor 121, and the second

sensor 122 of the foregoing robot cleaner 1.

That is, the sensor unit 120 may include a plurality of different sensors capable

of sensing a surrounding environment of the robot cleaner 1, and information about the

surrounding environment of the robot cleaner 1 sensed by the sensor unit 120 may be

transmitted to the control device by the controller 110. Herein, the information about the

surrounding environment may include, for example, existence of an obstacle, sensing of

a cliff, sensing of collision, etc.

The controller 110 may control operations of the first motor 56 and/or the second

motor 57 based on information from the first sensor 121. For example, when the bumper

58 contacts an obstacle during traveling of the robot cleaner 1, a contact position of the

bumper 58 may be recognized by the first sensor 121 and the controller 110 may control

the operations of the first motor 56 and/or the second motor 57 to leave the contact

position.

Based on information from the second sensor 122, when a distance between the

robot cleaner 1 and an obstacle is less than or equal to a predetermined value, the

controller 110 may control the operations of the first motor 56 and/or the second motor

57 such that the robot cleaner 1 changes the traveling direction thereof or moves in a

direction away from the obstacle.

According to a distance sensed by the first lower sensor 123, the second lower

sensor 124, or the third lower sensor 125, the controller 110 may control the operations

of the first motor 56 and/or the second motor 57 such that the robot cleaner 1 stops or changes the traveling direction thereof.

According to a distance sensed by the displacement sensor 126, the controller

110 may control the operations of the first motor 56 and/or the second motor 57 such that

the robot cleaner 1 changes the traveling direction thereof. For example, when the robot

cleaner 1 deviates from an input traveling path or traveling pattern due to slippage

occurring therein, the displacement sensor 126 may measure a distance deviating from

the input traveling path or traveling pattern, and the controller 110 may control the

operations of the first motor 56 and/or the second motor 57 to compensate for the

deviating distance.

According to an angle sensed by the angle sensor 127, the controller 110 may

control the operations of the first motor 56 and/or the second motor 57 such that the robot

cleaner 1 changes the traveling direction thereof. For example, when the robot cleaner 1

deviates from the input traveling direction due to slippage occurring therein, the angle

sensor 127 may measure an angle deviating from the input traveling direction, and the

controller 110 may control the operations of the first motor 56 and/or the second motor

57 to compensate for the deviating angle.

Meanwhile, the power source unit 130 may receive external power or internal

power and supply power required for operations of components, under control of the

controller 110. The power source unit 130 may include the battery 135 of the robot cleaner

1.

The water supply unit 140 may include the water container 141, the water supply

tube 142, and the water pump 143 of the above-described robot cleaner 1. The water

supply unit 140 may adjust the amount of supply of liquid (water) to the first mopping

cloth 30 and the second mopping cloth 40, according to a control signal of the controller

110. The controller 110 may control a driving time of a motor for driving the water pump

143 to adjust the amount of water supply.

The driving unit 150 may include the first motor 56 and the second motor 57 of

the robot cleaner 1 described above. The driving unit 150 may cause the robot cleaner 1

to rotate or move straight according to the control signal of the controller 110.

The communication unit 160 may be disposed inside the body 50, and may

include at least one module enabling wireless communication between the robot cleaner

1 and a wireless communication system, between the robot cleaner 1 and a preset

peripheral device, or between the robot cleaner 1 and a preset external server.

For example, at least one module may include at least one of an infrared (IR)

module for IR communication, an ultrasonic module for ultrasonic communication, or a

short-range communication module such as a wireless fidelity (WiFi) module or a

Bluetooth module. Alternatively, a wireless Internet module may be included to transmit

or receive data to or from a preset device through various wireless techniques such as a

wireless local area network (WLAN), WiFi, etc.

Meanwhile, the display unit 170 may display information to be provided to a

user. For example, the display unit 170 may include a display that displays a screen. In

this case, the display may be exposed on a top surface of the body 50.

The display unit 170 may also include a speaker that outputs sound. For example,

the speaker may be built in the body 50. In the body 50, a hole may be formed to pass

sound therethrough at a position corresponding to a position of the speaker. A source of

sound output through the speaker may be sound data stored previously in the robot cleaner

1. For example, the previously stored sound data may regard to a voice guide

corresponding to each function of the robot cleaner 1 or an alert sound indicating an error.

The display unit 170 may include any one of a light-emitting diode (LED), a

liquid crystal display (LCD), a plasma display panel (PDP), and an organic light-emitting diode (OLED).

The memory 180 may include various data for driving and operations of the

robot cleaner 1. The memory 180 may include application programs and related various

data for autonomous traveling of the robot cleaner 1. The memory 180 may also store

respective data sensed by the sensor unit 120 and include setting information, etc., about

user-selected or user-input settings (values) (e.g., a cleaning reservation time, a cleaning

mode, the amount of water supply, an LED brightness level, a volume of the alert sound,

etc.).

The memory 180 may include information about a cleaning surface to be cleaned,

currently given to the robot cleaner 1. For example, the information about the cleaning

surface to be cleaned may be map information autonomously mapped by the robot cleaner

1. The map information, i.e., a map may include various information set by the user for

each area of the cleaning surface to be cleaned.

FIG. 4 is a flowchart of a method of controlling a robot cleaner, according to an

embodiment of the present disclosure, and FIGS. 5 through 9 are views for roughly

describing a traveling path of the robot cleaner 1 based on the method of controlling the

robot cleaner, according to an embodiment of the present disclosure.

Referring to FIGS. ID, iE, and 4 through 9, a description will be made of a

method of controlling a robot cleaner, according to an embodiment of the present

disclosure.

The method of controlling a robot cleaner 1 according to an embodiment of the

present disclosure may include straight traveling operation S10.

In straight traveling operation S1, the controller 110 may control the robot

cleaner I to travel straight from a start point P1 to a predetermined target point P2.

For example, in straight traveling operation S10, the user may input coordinates of a particular position or a particular structure in a cleaning area, through a terminal (not shown).

In another example, the user may instruct the robot cleaner 1 through the

terminal (not shown) to continuously move straight until a particular obstacle appears.

In this case, the controller 110 may control the traveling direction line H of the

robot cleaner 1 to be directed to the target point P2. That is, the controller 110 may

calculate an angle difference between the traveling direction line H and the target point

P2 and drive the first motor 56 and/or the second motor 57 to match the traveling direction

line H to the target point P2 by rotating the robot cleaner 1 by the angle difference.

In this case, the controller 110 may drive the first motor 56 and the second motor

57 in the same rotation direction at the same rotation speed to rotate the robot cleaner 1

at the same place. That is, the first rotation plate 10 and the second rotation plate 20 may

rotate the robot cleaner 1 at the same place by rotating in the same rotation direction at

the same rotation speed.

Meanwhile, according to an embodiment of the present disclosure, when the

robot cleaner 1 slips when rotating at the same place, the controller 110 may perform a

control operation to compensate for the slippage.

When a traveling line LD connecting the start point P Ito the target point P2

coincides with the traveling direction line H of the robot cleaner 1, the controller 110 may

start straight traveling.

Upon start of the straight traveling, the controller 110 may rotate the first motor

56 and the second motor 57 in opposite directions and at the same speed. That is, as the

first rotation plate 10 and the second rotation plate 20 may rotate in the opposite directions

at the same rotation speed, the first rotation plate 10 and the second rotation plate 20 may

cause the robot cleaner 1 to travel straight. For example, when viewed from top, when the first rotation plate 10 rotates counterclockwise and the second rotation plate 20 rotates clockwise, the robot cleaner 1 may move forward.

Meanwhile, when the robot cleaner 1 travels straight as described above, the

robot cleaner 1 may deviate from the traveling line LD due to a frictional force difference

than the floor surface B.

In particular, when compared to a robot cleaner capable of traveling straight

based on rotation of wheels, the robot cleaner 1 which travels by a frictional force between

the floor surface B and the mopping cloths 30 and 40 based on rotation of the pair of

mopping cloths 30 and 40 in the present disclosure has a difficulty in traveling straight.

That is, in the robot cleaner 1 of a type where the pair of mopping cloths 30 and

40 rotate, a frictional force between the first mopping cloth 30 and the floor surface B and

a frictional force between the second mopping cloth 40 and the floor surface B may be

often different from each other depending on a condition (non-uniformity) of the floor

surface B or a difference in contamination level or moisture content between the pair of

the mopping cloths 30 and 40.

As a result, it may be difficult for the robot cleaner 1 to travel straight to the

target point P2.

To solve this problem, in the present disclosure, it is determined whether the

robot cleaner 1 deviates from the traveling line LD connecting the start point PI to the

target point P2, and when it is determined that the robot cleaner 1 deviates from the

traveling line LD, a control operation for compensating for the deviation may be

performed.

Hereinbelow, a detailed control method will be described.

The method of controlling the robot cleaner 1 according to the present disclosure

may include deviation determination operation S20 of determining whether the robot cleaner 1 deviates from the traveling line LD.

In deviation determination operation S20, the controller 110 may determine that

the robot cleaner 1 deviates from the traveling line LD when a shortest distance d between

the traveling line LD and the robot cleaner 1 is greater than or less than a predetermined

reference distance D (d > D).

More specifically, in deviation determination operation S20, the controller 110

may measure a shortest distance between a position of each component of the robot

cleaner 1 and the traveling line LD through the displacement sensor 126. For example,

the controller 110 may receive information about a distance between the displacement

sensor 126 and a reference point (the start point PI or a predetermined point on the

traveling line LD) and calculate a distance between the traveling line LD and the

displacement sensor 126 based on the received information. The controller 110 may

calculate the shortest distance between the position of each component of the robot

cleaner 1 and the traveling line LD, by using relative position information between the

displacement sensor 126 and another component of the robot cleaner 1.

Thus, the controller 110 may measure a shortest distance dl between the front

end of the robot cleaner 1 and the traveling line LD, a shortest distance d2 between a rear

end of the robot cleaner 1 and the traveling line LD, a shortest distance between the

midpoint C of the connection line LI and the traveling line LD, the shortest distance d

between the body 50 and the traveling line LD, etc.

The controller 110 may determine that the robot cleaner 1 deviates from the

traveling line LD when the measured shortest distance d between the traveling line LD

and the robot cleaner 1 is greater than or equal to the predetermined reference distance D

(d > D). For example, the reference distance D may be about 3 cm.

Alternatively, the controller 110 may determine that the robot cleaner 1 deviates from the traveling line LD when a shortest distance dl between the front end of the robot cleaner 1 and the traveling line LD is greater than or equal to the predetermined reference distance D (dl>D). For example, the reference distance D may be about 3 cm.

Alternatively, the controller 110 may draw virtual deviation reference lines LR

arranged in parallel to the traveling line LD with a predetermined reference distance D to

the traveling line LD and determine that the robot cleaner 1 deviates from the traveling

line LD when the robot cleaner 1 is not located between the driving line LD and the

deviation reference lines LR.

With this configuration, the robot cleaner 1 may quickly determine deviation

from a straight path and change the direction thereof to return to the straight path.

When it is determined that the robot cleaner 1 deviates from the traveling line

LD in deviation determination operation S20, a straight-traveling correction operation of

rotating the body 50 to cause the robot cleaner 1 to approach the traveling line LD may

be performed. In the straight-traveling correction operation, the controller 110 may cause

the rotation speeds of the pair of rotation plates 10 and 20 to be different from each other,

thus controlling the robot cleaner 1 to travel close to the traveling line LD.

The straight-traveling correction operation may include first correction operation

S30 of rotating a rotation plate located far from the traveling line LD between the pair of

rotation plates 10 and 20 faster than the rotation plate located close to the traveling line

LD.

That is, in first correction operation S30, the controller 110 may control an output

of the motor located far from the traveling line LD to be greater than an output of the

motor located close to the traveling line LD.

That is, in first correction operation S30, the controller 110 may control a relative

movement speed of the mopping cloth located far from the traveling line LD with respect to the floor surface B to be higher than a relative movement speed of the mopping cloth located close to the traveling line LD with respect to the floor surface B.

For example, as shown in FIG. 6, when the robot cleaner 1 slips to the left and

thus deviates from the traveling line LD, the controller 110 may operate such that an

output of the first motor 56 located far from the traveling line LD is greater than an output

of the second motor 57. As a result, a rotation speed wl of the first rotation plate 10

located far from the traveling line LD may be higher than a rotation speed w2 of the

second rotation plate 20 located close to the traveling line LD (wI > w2). The relative

movement speed of the first mopping cloth 30 with respect to the floor surface B may be

higher than that of the second mopping cloth 40 with respect to the floor surface B.

In another example, symmetrically to FIG. 6, the robot cleaner 1 may slip to the

right and thus deviate from the traveling line LD, and the controller 110 may operate such

that the output of the second motor 57 located far from the traveling line LD is greater

than the output of the first motor 56. As a result, the rotation speed w2 of the second

rotation plate 20 located far from the traveling line LD may be higher than the rotation

speed wi of the first rotation plate 10 located close to the traveling line LD (w2 > wI).

The relative movement speed of the second mopping cloth 40 with respect to the floor

surface B may be higher than that of the first mopping cloth 30 with respect to the floor

surface B.

In first correction operation S30 of the present disclosure, the first rotation plate

10 and the second rotation plate 20 may rotate in the opposite directions at different

rotation speeds. That is, in the current embodiment, the robot cleaner 1 preferably changes

the direction thereof while maintaining traveling (movement).

With such a configuration, it is possible to prevent the robot cleaner 1 from

wandering (stopping or rotating at the same place) due to a failure to find a traveling direction after deviation from a straight line (i.e., the traveling line LD).

Meanwhile, in first correction operation S30, as the shortest distance d between

the traveling line LD and the robot cleaner 1 increases, an angle by which the robot

cleaner 1 rotates may increase. Alternatively, in another embodiment, as the shortest

distance dl between the traveling line LD and the front end of the robot cleaner 1

increases, the angle by which the robot cleaner 1 rotates may increase.

That is, as the deviating distance of the robot cleaner 1 from the traveling line

LD increases, the controller 110 may drive the first motor 56 and/or the second motor 57

to increase a speed difference Aw between the rotation speed of the rotation plate located

far from the traveling line LD and the rotation speed of the rotation plate located close to

the traveling line LD.

In first correction operation S30, as a change per time (Ad/At) of the shortest

distance d between the traveling line LD and the robot cleaner 1 increases, the angle by

which the robot cleaner 1 rotates may increase. Alternatively, as a change per time

(Adl/At) of the shortest distance dl between the traveling line LD and the front end of

the robot cleaner 1 increases, the angle by which the robot cleaner 1 rotates may increase.

That is, as a deviating change per time of the robot cleaner 1 from the traveling

line LD increases, the controller 110 may drive the first motor 56 and/or the second motor

57 to increase the speed difference Aw between the rotation speed of the rotation plate

located far from the traveling line LD and the rotation speed of the rotation plate located

close to the traveling line LD.

Meanwhile, in first correction operation S30, a control output for returning the

robot cleaner 1 to the traveling line LD by rotating the robot cleaner 1 may be as below.

Pr x dl + Dr xAdl/At

That is, in first correction operation S30, the controller 110 may output a proportional action Pr that is proportional to the shortest distance dl between the traveling line LD and the front end of the robot cleaner 1 and a derivative action Dr that is proportional to the change per time Adl/At of the shortest distance dl between the traveling line LD and the front end of the robot cleaner 1.

With such a configuration, in first correction operation S30, the robot cleaner 1

may turn toward the traveling line LD and travel to approach the traveling line LD.

After first correction operation S30, the controller 110 may continuously

measure the shortest distance between the robot cleaner 1 and the traveling line LD and

go to second correction operation S50 to be described later when the shortest distance

between the robot cleaner 1 and the traveling line LD decreases.

The straight-traveling correction operation may include second correction

operation S50 of increasing the rotation speed of the rotation plate located close to the

traveling line LD between one pair of rotation plates, after first correction operation S30.

In second correction operation S50, as the shortest distance d between the

traveling line LD and the robot cleaner 1 decreases, the rotation speed of the rotation plate

located close to the traveling line LD may be increased. In this case, the rotation speed of

the rotation plate located far from the traveling line LD may be gradually reduced.

For example, as shown in FIG. 8, when the robot cleaner 1 slips to the left,

deviates from the traveling line LD, and then turns to move toward the traveling line LD,

the controller 110 may gradually increase the rotation speed w2 of the second rotation

plate 20 located close to the traveling line LD. That is, the controller 110 may gradually

increase the rotation speed of the second motor 57. The controller 110 may gradually

reduce the rotation speed wl of the first rotation plate 10 located far from the traveling

line LD. That is, the controller 110 may gradually reduce the rotation speed of the first

motor 56. Thus, the relative velocity of the second mopping cloth 40 with respect to the floor surface B may gradually increase, and the relative velocity of the first mopping cloth

30 with respect to the floor surface B may gradually decrease.

In another example, symmetrically to FIG. 8, when the robot cleaner 1 slips to

the right, deviates from the traveling line LD, and then turns to move toward the traveling

line LD, the controller 110 may gradually increase the rotation speed w Iof the first

rotation plate 10 located close to the traveling line LD. That is, the controller 110 may

gradually increase the rotation speed of the first motor 56. The controller 110 may

gradually reduce the rotation speed w2 of the second rotation plate 20 located far from

the traveling line LD. That is, the controller 110 may gradually reduce the rotation speed

of the second motor 57. Thus, the relative velocity of the first mopping cloth 30 with

respect to the floor surface B may gradually increase, and the relative velocity of the

second mopping cloth 40 with respect to the floor surface B may gradually decrease.

In second correction operation S50, as the change per time (Ad/At) of the shortest

distance d between the traveling line LD and the robot cleaner 1 increases, the controller

110 may increase the rotation speed of the rotation plate located close to the traveling line

LD. The controller 110 may gradually reduce the rotation speed of the rotation plate

located far from the traveling line LD.

In second correction operation S50, a distance difference (dl - d2) between the

front end of the robot cleaner 1 and the rear end of the robot cleaner 1 with respect to the

traveling line LD has a negative value, and as the negative value increases, the rotation

speed of the rotation plate located close to the traveling line LD may be increased. The

controller 110 may gradually reduce the rotation speed of the rotation plate located far

from the traveling line LD.

In second correction operation S50, a change per time (A(dl-d2)/At) of the

distance difference (dl - d2) between the front end of the robot cleaner 1 and the rear end of the robot cleaner 1 with respect to the traveling line LD has a negative value, and as the negative value increases, the controller 110 may increase the rotation speed of the rotation plate located close to the traveling line LD. The controller 110 may gradually reduce the rotation speed of the rotation plate located far from the traveling line LD.

Meanwhile, in second correction operation S50, a control output for rotating the

robot cleaner 1 to parallelize the robot cleaner 1 to the traveling line LD may be as below.

Pp x (d1-d2) + Dp x A(dl -d2)/At

That is, in second correction operation S50, the controller 110 may output a

proportional action Pp that is proportional to the distance difference (d1 - d2) between the

front end of the robot cleaner 1 and the rear end of the robot cleaner 1 with respect to the

traveling line LD and a derivative action Dp that is proportional to the change per time

(A(dl-d2)/At) of the distance difference (dl - d2) between the front end of the robot

cleaner 1 and the rear end of the robot cleaner 1 with respect to the traveling line LD.

Meanwhile, in second correction operation S50, a weight value may be applied

to increase/reduction of the rotation speeds of one pair of rotation plates according to a

distance between the traveling line LD and the robot cleaner 1.

That is, in second correction operation S50, a weight value may be applied

between a control output for returning the robot cleaner 1 to the traveling line LD by

rotating the robot cleaner 1 and a control output for parallelizing the robot cleaner 1 to

the traveling line LD by rotating the robot cleaner 1.

The control output for rotating the robot cleaner 1 including the weight value in

second correction operation S50 may be as below.

a x (Pr x d1 + Dr xAd1/At)+(1- a) x (Pp x (d1-d2) + Dp xA(dl-d2)/At)

In this case, a weight value a may mean a rate of the shortest distance dl between the traveling line LD and the front end of the robot cleaner 1 to the reference distance D.

For example, when the reference distance D is 3 cm and the shortest distance dl between

the front end of the robot cleaner 1 and the traveling line LDis 1 cm, then the weight value

a may be 1/3.

Thus, when the shortest distance dl between the traveling line LD and the front

end of the robot cleaner 1 is greater than or equal to the reference distance D, there may

be only the control output for returning the robot cleaner 1 to the traveling direction LD

by rotating the robot cleaner 1. When the robot cleaner 1 returns to the traveling line LD,

there may be only the control output for parallelizing the robot cleaner 1 to the traveling

line LD by rotating the robot cleaner 1.

For example, when the midpoint C is positioned on the traveling line LD after

any one mopping cloth passes through the traveling line LD, the rotation speed of the

mopping cloth having passed through the traveling line LD may be higher than that of the

mopping cloth that has not passed through the traveling line LD.

With this configuration, when the robot cleaner 1 converges to the traveling line

LD, the controller 110 may reduce the rotation speed of the rotation plate located far from

the traveling line LD and increase the rotation speed of the rotation plate located close to

the traveling line LD, thus turning the robot cleaner 1 to gently converge to the traveling

line LD.

After second correction operation S50, the controller 110 may determine using

the displacement sensor 126 whether the robot cleaner 1 travels being located on the

traveling line LD, in operation S60. That is, when the distance between the front end of

the robot cleaner 1 and the traveling line LD is 0 and the distance difference (dl - d2)

between the front end of the robot cleaner 1 and the rear end of the robot cleaner 1 with

respect to the traveling line LD is 0, the controller 110 may determine that the robot cleaner 1 is traveling on the traveling line LD toward the target point P2.

In this case, when the controller 110 determines that the robot cleaner 1 is

traveling on the traveling line LD, the controller 110 may rotate one pair of rotation plates

10 and 20 at the same speed to cause the robot cleaner 1 to travel straight, in operation

S70. That is, when the controller 110 determines that the robot cleaner 1 has returned to

the traveling line LD, the controller 110 may drive the first motor 56 and the second motor

57 at the same rotation speed. The rotation directions of the first motor 56 and the second

motor 57 are opposite to each other. For example, the rotation speeds of the first rotation

plate 10 and the second rotation plate 20 are the same as each other, but when the first

rotation plate 10 rotates counterclockwise, then the second rotation plate 20 may rotate

clockwise.

Thereafter, the controller 110 may sense using the displacement sensor 126

whether the robot cleaner 1 moves away from the traveling line LD, in operation S80.

In this case, the controller 110 may return the robot cleaner 1 to the traveling line

LD, regardless of whether the shortest distance dl between the front end of the robot

cleaner 1 and the traveling line LD is greater than or equal to the predetermined reference

distance D. That is, when the front end of the robot cleaner 1 moves away from the

traveling line LD, the controller 110 may control the rotation speed of the rotation plate

located far from the traveling line LD to be higher than that of the rotation plate located

close to the traveling line LD.

Thereafter, until the robot cleaner 1 arrives at the target point P2, a process after

deviation determination operation S20 may be repeated.

Thus, according to the present disclosure, even when the robot cleaner 1 deviates

from the traveling line LD by slipping, the robot cleaner 1 may sense the deviation and

quickly return to the traveling line LD to travel straight.

In the current embodiment, even when the robot cleaner 1 deviates from the

traveling line LD, the robot cleaner 1 continuously turns toward the traveling line LD,

thereby maintaining cleaning quality for a cleaning area around the traveling line LD.

FIG. 10 is a flowchart of a method of controlling a robot cleaner, according to

another embodiment of the present disclosure, and FIGS. 11 through 14 are views for

roughly describing a traveling path of the robot cleaner 1 based on the method of

controlling the robot cleaner 1, according to another embodiment of the present disclosure.

Referring to FIGS. ID, IE, and 10 through 14, a description will be made of a

method of controlling a robot cleaner, according to another embodiment of the present

disclosure.

The method of controlling a robot cleaner according to the current embodiment

may include straight traveling operation S110.

In straight traveling operation S110, the controller 110 may cause the robot

cleaner 1 to travel straight from the start point P Ito the predetermined target point P2.

For example, in straight traveling operation S110, the user may input coordinates

of a particular position or a particular structure in a cleaning area, through a terminal (not

shown).

In another example, the user may instruct the robot cleaner 1 through the

terminal (not shown) to continuously move straight until a particular obstacle appears.

In this case, the controller 110 may control the forward traveling direction line

Hf of the robot cleaner 1 to be directed to the target point P2. That is, the controller 110

may calculate an angle difference between the forward traveling direction line Hf and the

target point P2 and drive the first motor 56 and/or the second motor 57 to match the

forward traveling direction line Hf with the target point P2 by rotating the robot cleaner

1 by the angle difference.

In this case, the controller 110 may drive the first motor 56 and the second motor

57 in the same rotation direction at the same rotation speed to rotate the robot cleaner 1

at the same place. That is, the first rotation plate 10 and the second rotation plate 20 may

rotate the robot cleaner 1 at the same place by rotating in the same rotation direction at

the same rotation speed.

Meanwhile, according to an embodiment of the present disclosure, when the

robot cleaner 1 slips during rotation at the same place, the controller 110 may perform a

control operation to compensate for the slippage.

When the traveling line LD connecting the start point P Ito the target point P2

coincides with the traveling direction line H of the robot cleaner 1, the controller 110 may

start straight traveling.

Upon start of the straight traveling, the controller 110 may rotate the first motor

56 and the second motor 57 in the opposite directions at the same speed. That is, as the

first rotation plate 10 and the second rotation plate 20 rotate in the opposite directions at

the same rotation speed, the first rotation plate 10 and the second rotation plate 20 may

cause the robot cleaner 1 to travel straight. For example, when viewed from top, when the

first rotation plate 10 rotates counterclockwise and the second rotation plate 20 rotates

clockwise, the robot cleaner 1 may move forward.

The method of controlling the robot cleaner 1 according to the current

embodiment may include deviation determination operation S120 of determining whether

the robot cleaner 1 deviates from the traveling line LD.

In deviation determination operation S120, the controller 110 may determine that

the robot cleaner 1 deviates from the traveling line LD when an angle between the

traveling direction line H and the traveling line LD is greater than or equal to a

predetermined reference angle. More specifically, when an angle formed by intersection between the backward traveling direction line Hb and the traveling line LD is greater than or equal to the predetermined reference angle, the controller 110 may determine that the robot cleaner 1 deviates from the traveling line LD. For example, the reference angle may be greater than or equal to 30 degrees and less than or equal to 60 degrees.

When it is determined that the robot cleaner 1 deviates from the traveling line

LD in deviation determination operation S120, the controller 110 may perform straight

traveling correction operations S130 and S140.

On the other hand, in the current embodiment, straight-traveling correction

operations S130 and S140 may be directly performed after straight-traveling correction

operation Sl10, without undergoing deviation determination operation S120. In this case,

when the traveling direction line H of the robot cleaner 1 does not coincide with the

traveling line LD, the controller 110 may immediately rotate the robot cleaner 1.

In straight-traveling correction operations S130 and S140, the controller 110

may rotate the body 50 to cause the robot cleaner 1 to approach the traveling line LD.

More specifically, the controller 110 may set a virtual target intersection point P4 on the

traveling line LD in operation S130 and control the rotation speeds of the pair of rotation

plates 10 and 20 to cause the forward traveling direction line Hf of the robot cleaner I to

coincide with the target intersection point P4 in operation S140.

Sequentially referring to straight-traveling correction operations S130 and S140,

the controller 110 may form a virtual movement point P3 corresponding to a position of

the midpoint C of the robot cleaner 1 on the traveling line LD. In this case, the movement

point P3 may be disposed at the shortest distance from the midpoint C. That is, a virtual

line connecting the movement point P3 to the midpoint C may be perpendicular to the

traveling line LD. With this configuration, the movement point P3 may indicate a position

on the traveling line LD of the robot cleaner 1.

Next, the controller 110 may form the virtual target intersection point P4 at a

predetermined distance from the movement point P3 toward the target point P2 on the

traveling line LD. For example, the target intersection point P4 may be disposed at a

distance of 50 cm from the movement point P3 toward the target point P2, in operation

S130.

After the virtual target intersection point P4 is set on the traveling line LD, the

controller 110 may control the rotation speeds (outputs) of the first motor 56 and the

second motor 57 to cause the forward traveling direction line Hf to coincide with the

target intersection point P4. The controller 110 may travel toward the target intersection

point P4 while causing the forward traveling direction line Hf to coincide with the target

intersection point P4, in operation S140.

Meanwhile, in straight-traveling correction operations S130 and S140, a control

output for causing the robot cleaner 1 to converge to the traveling line LD by rotating the

robot cleaner 1 may be as below.

. Ps x E + Is x J + Ds x AO/At + Pr x d + Ir xJd+ Dr x Ad/At That is, the control output for causing the robot cleaner 1 to converge to the

traveling line LD may include a control output for aligning the robot cleaner 1 to the

traveling line LD and a control output for returning the robot cleaner 1 close to the

traveling line LD.

In this case, to align the robot cleaner 1 to the traveling line LD, the controller

110 may output a proportional action Ps that is proportional to an angle difference 0

between the forward traveling direction line Hf and the target intersection point P4 with

respect to the midpoint C, an integral action Is that is proportional to an integral value of

the angle difference 0, and a derivative action Ds that is proportional to a change per time

(A/At) of the angle difference 0.

In addition, to return the robot cleaner 1 to the traveling line LD, the controller

110 may output the proportional action Pr that is proportional to the shortest distance d

of the reference line LR with respect to the midpoint C, an integral action Ir that is

proportional to an integral value of the shortest distance d, and the derivative action Dr

that is proportional to the change per time (Ad/At) of the shortest distance d.

More specifically, the controller 110 may control the rotation speed of the motor

located far from the target intersection point P4 to be higher than the rotation speed of the

motor located close to the target intersection point P4. Thus, the rotation speed of the

rotation plate located far from the target intersection point P4 may be higher than the

rotation speed of the rotation plate located close to the target intersection point P4. The

relative movement speed of the mopping cloth located far from the target intersection

point P4 with respect to the floor surface B may be higher than the relative movement

speed of the mopping cloth located close to the target intersection point P4.

For example, as shown in FIG. 11, when the angle difference 0 between the

forward traveling direction line Hf and the target intersection point P4 with respect to the

midpoint C occurs due to deviation of the robot cleaner 1 to the left of the traveling line

LD, the controller 110 may rotate the first motor 56 located far from the target intersection

point P4 faster than the second motor 57 located close to the target intersection point P4.

As a result, the first rotation plate 10 may be rotated faster than the second rotation plate

20. The relative movement speed of the first mopping cloth 30 with respect to the floor

surface B may be higher than that of the second mopping cloth 40 with respect to the floor

surface B.

Next, when the first rotation plate 10 is located closer to the target intersection

point P4 than the second rotation plate 20, the controller 110 may control the rotation speed of the second rotation plate 20 to be higher than that of the first rotation plate 10.

As a result, at the target intersection point P4, the traveling line LD and the

forward traveling direction line Hf may intersect each other (see FIG. 12).

Meanwhile, as the robot cleaner 1 moves to the target intersection point P4, the

movement point P3 linked to positional movement of the midpoint C may be moved

toward the target point P2. The target intersection point P4 located by a predetermined

interval X from the movement point P3 may be moved to the target point P2 (see FIG.

13).

Thus, the target intersection point P4, the robot cleaner 1, and the forward

traveling direction line Hf may gradually converge toward the target point P2 (see FIG.

14).

Therefore, at the target intersection point P4, the traveling line LD and the

forward traveling direction line Hf may be maintained as intersecting each other, in

operation S150.

Thereafter, the controller 110 may maintain straight traveling while repeating the

foregoing process until the robot cleaner 1 arrives at the target point P2, in operation S160.

Thus, according to the current embodiment, even when the robot cleaner 1

deviates from the traveling line LD by slipping, the robot cleaner 1 may quickly return to

the traveling line LD to travel straight.

In the current embodiment, even when the robot cleaner 1 deviates from the

traveling line LD, the robot cleaner 1 continuously turns toward the traveling line LD,

thereby maintaining cleaning quality for a cleaning area around the traveling line LD.

Moreover, in the current embodiment, the robot cleaner 1 turns while drawing a

natural curve without suddenly changing a direction thereof, thereby increasing energy

efficiency and extending the lifespan of the robot cleaner 1.

Although the present disclosure has been described in detail through specific

embodiments, it is intended to describe the present disclosure in detail, without limiting

the present disclosure thereto, and it is apparent that the present disclosure may be

modified or improved by those of ordinary skill in the art within the technical spirit of the

present disclosure.

All simple modifications and variations of the present disclosure fall within the

scope of the present disclosure, and the specific protection range of the present disclosure

will be made clear by the appended claims.

Claims (20)

1. [Claims]

   [Claim 1]

   A robot cleaner that travels along a virtual traveling line connecting a start point

   to a predetermined target point in a straight line, the robot cleaner comprising:

   a body having formed therein a space for accommodating a battery, a water

   container, and a motor; and

   a pair of rotation plates that have coupled to lower sides thereof, mopping cloths

   facing a floor surface, and are rotatably disposed on a bottom surface of the body,

   wherein when a shortest distance between the body and the traveling line is

   greater than or equal to a predetermined reference distance, rotation speeds of the pair of

   rotation plates are different from each other to approach the traveling line.
2. [Claim 2]

   The robot cleaner of claim 1, wherein the pair of rotation plates are such that the

   rotation speed of the rotation plate located far from the traveling line is higher than the

   rotation speed of the rotation plate located close to the traveling line.
3. [Claim 3]

   The robot cleaner of claim 1 or claim 2, wherein the pair of rotation plates are

   such that when the shortest distance between the body and the traveling line decreases,

   the rotation speed of the rotation plate located close to the traveling line is increased.
4. [Claim 4]

   The robot cleaner of any one of claims 1 to 3, wherein the pair of rotation plates

   comprises: a first rotation plate that has coupled to a lower side thereof a first mopping cloth facing the floor surface and is rotatably disposed on the bottom surface of the body; and a second rotation plate that has coupled to a lower side thereof a second mopping cloth facing the floor surface and is rotatably disposed on the bottom surface of the body, and when a midpoint between a rotation axis of the first rotation plate and a rotation axis of the second rotation plate is placed on the traveling line after the first mopping cloth passes through the traveling line, the rotation speed of the first rotation plate is higher than the rotation speed of the second rotation plate.
5. [Claim 5]

   The robot cleaner of any one of claims I to 4, further comprising:

   a virtual connection line connecting rotation axes of the pair of rotation plates to

   each other; and

   a virtual traveling direction line perpendicularly intersecting the connection line

   at the midpoint of the connection line and extending in parallel to the floor surface,

   wherein the traveling direction line comprises:

   a forward traveling direction line extending in parallel to the floor surface toward

   a direction in which the battery is disposed with respect to the connection line; and

   a backward traveling direction line extending in parallel to the floor surface

   toward a direction in which the water container is disposed with respect to the connection

   line, and

   the body rotates such that the forward traveling direction line and the traveling

   line intersect each other, when an angle formed by intersection between the backward

   traveling direction line and the traveling line is greater than or equal to a predetermined reference angle.
6. [Claim 6]

   The robot cleaner of any one of claims I to 4, further comprising:

   a virtual connection line connecting rotation axes of the pair of rotation plates to

   each other; and

   a virtual traveling direction line perpendicularly intersecting the connection line

   at the midpoint of the connection line and extending in parallel to the floor surface,

   wherein the traveling direction line comprises:

   a forward traveling direction line extending in parallel to the floor surface toward

   a direction in which the battery is disposed with respect to the connection line; and

   a backward traveling direction line extending in parallel to the floor surface

   toward a direction in which the water container is disposed with respect to the connection

   line, and

   the pair of rotation plates are such that the rotation speed of the rotation plate

   located far from the traveling line is higher than the rotation speed of the rotation plate

   located close to the traveling line, when an angle formed by intersection between the

   backward traveling direction line and the traveling line is greater than or equal to a

   predetermined reference angle.
7. [Claim 7]

   The robot cleaner of claim 5, further comprising:

   a virtual movement point located on the traveling line and disposed at a shortest

   distance to the midpoint of the connection line; and

   a virtual target intersection point located on the traveling line and disposed at a predetermined distance from the movement point toward the target point, wherein the target intersection point is a point at which the traveling line and the forward traveling direction line intersect each other.
8. [Claim 8]

   The robot cleaner of any one of claims I to 4, further comprising:

   a virtual connection line connecting rotation axes of the pair of rotation plates to

   each other;

   a virtual traveling direction line perpendicularly intersecting the connection line

   at the midpoint of the connection line and extending in parallel to the floor surface;

   a virtual movement point located on the traveling line and disposed at a shortest

   distance to the midpoint of the connection line; and

   a virtual target intersection point located on the traveling line and disposed at a

   predetermined distance from the movement point toward the target point,

   wherein the pair of rotation plates are such that the rotation speed of the rotation

   plate located far from the target intersection point is higher than the rotation speed of the

   rotation plate located close to the target intersection point.
9. [Claim 9]

   The robot cleaner of any one of claims I to 8, wherein a relative movement speed

   of a mopping cloth located far from the traveling line with respect to the floor surface is

   higher than a relative movement speed of a mopping cloth located close to the traveling

   line with respect to the floor surface.
10. [Claim 10]

    The robot cleaner of any one of claims 1 to 9, wherein an output of a motor

    located far from the traveling line is greater than an output of a motor located close to the

    traveling line.
11. [Claim 11]

    A method of controlling a robot cleaner that comprises a pair of rotation plates

    having coupled to lower sides thereof, mopping cloths facing a floor surface, and travels

    by rotating the pair of rotation plates, the method comprising:

    a straight traveling operation of causing the robot cleaner to travel straight along

    a virtual traveling line connecting a start point to a predetermined target point in a straight

    line; and

    a straight-traveling correction operation of rotating a body of the robot cleaner

    to approach the traveling line by changing the rotation speed of rotation plates when the

    robot cleaner deviates from the traveling line.
12. [Claim 12]

    The method of claim 11, wherein in the straight traveling operation, the pair of

    rotation plates are rotated at a same speed.
13. [Claim 13]

    The method of claim 11 or claim 12, wherein in the straight traveling operation,

    rotation directions of the pair of rotation plates are opposite to each other.
14. [Claim 14]

    The method of any one of claims 11 to 13, wherein the straight-traveling correction operation comprises a first correction operation of rotating a rotation plate located far from the traveling line faster than a rotation plate located close to the traveling line.
15. [Claim 15]

    The method of claim 14, wherein the straight-traveling correction operation

    further comprises a second correction operation of increasing the rotation speed of the

    rotation plate located close to the traveling line, after the first correction operation.
16. [Claim 16]

    The method of any one of claims 11 to 15, wherein in the straight-traveling

    correction operation, a virtual movement point disposed at a shortest distance from the

    robot cleaner is generated on the traveling line, a target intersection point at a

    predetermined distance from the movement point to the target point is generated, and the

    robot cleaner is caused to travel toward the target intersection point.
17. [Claim 17]

    The method of claim 14 or claim 15, wherein in the first correction operation, a

    rotation angle of the body of the robot cleaner increases as a shortest distance between

    the traveling line and the body of the robot cleaner increases.
18. [Claim 18]

    The method of claim 15, wherein in the second correction operation, the rotation

    speed of the rotation plate located close to the traveling line is increased as a shortest

    distance between the traveling line and the body of the robot cleaner decreases.
19. [Claim 19]

    The method of any one of claims 11 to 18, further comprising a deviation

    determination operation of determining whether the robot cleaner deviates from the

    traveling line.
20. [Claim 20]

    The method of claim 19, wherein the deviation determination operation

    comprises determining that the robot cleaner deviates from the traveling line, when a

    shortest distance between the traveling line and a front end of the robot cleaner is greater

    than or equal to a predetermined reference distance.