Patent Publication Number: US-2023136647-A1

Title: Autonomous cleaner

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of U.S. Pat. Application Serial No. 17/994,187, filed Nov. 25, 2022, which is a Continuation of U.S. Application No. 17/162,899, filed Jan. 29, 2021, which a Continuation of U.S. Application No. 16/014,994, filed Jun. 21, 2018, now U.S. Pat. No. 10,939,792, issued on Mar. 9, 2021, which is a Continuation of U.S. Application Serial No. 15/599,870 filed May 19, 2017, now U.S. Pat. No. 10,398,276, issued on Sep. 3, 2019, which claims priority under 35 U.S.C. §119 to Korean Application No. 10-2016-0062415, filed in Republic of Korea on May 20, 2016, Korean Application No. 10-2016-0072690, filed in Republic of Korea on Jun. 10, 2016, Korean Application No. 10-2016-0141106, filed in Republic of Korea on Oct. 27, 2016, and Korean Application No. 10-2016-0184446, filed in Republic of Korea on Dec. 30, 2016, whose entire disclosures are hereby incorporated by reference. 
    
    
     BACKGROUND 
     1. Field 
     The present disclosure relates to a robot cleaner and/or autonomous cleaner. 
     2. Background 
     In general, robots have been developed for industrial purposes to play a role in factory automation. Recently, application fields of robots have extended, and robots for medical purpose, space navigation robots, etc., and even home robots available that may be used in general houses have been developed. 
     A representative example of home robots is a robot cleaner. The robot cleaner performs a function of cleaning a floor while traveling by itself in a certain area. For example, a household robot cleaner is configured to suck dust (including foreign substances) on a floor or mop the floor while autonomously traveling inside a house. 
     Such a robot cleaner generally includes a rechargeable battery and various sensors for avoiding an obstacle during traveling. Thus, the robot cleaner performs a cleaning function while traveling by itself. 
     In order to allow the autonomous traveling of a robot cleaner to be smoothly performed, it is important to set the entire traveling route and sense obstacles on the traveling route. The robot cleaner may also perform a function of photographing or monitoring the inside of a house using autonomous traveling characteristics thereof. In order to perform the above-described functions, various sensors are used in the robot cleaner, but studies for an optimized design have not been satisfactory yet. 
     In addition, a typical robot cleaner has a structure in which a suction unit is provided at a lower portion of a cleaner body. However, the structure in which the suction unit is built in the cleaner body has problems in that the suction force of the robot cleaner is decreased, that the separation of a brush roller is impossible, and the like. Accordingly, there has been proposed a structure in which a suction unit is provided to protrude from a cleaner body as disclosed in the following patent documents. However, the structure has many problems to be solved in that the probability of collision between the suction unit and an obstacle is increased, that the suction unit is located in a blind spot of a sensing unit provided in the cleaner body, and the like. 
     In a structure in which a dust container is coupled to a cleaner body, and a dust container cover is coupled to the dust container, it is important to accurately assemble the components and easily perform the assembly. However, any product having the structure has not been released yet. 
     In addition, air introduced into a robot cleaner typically passes through a HEPA filter for filtering fine dust before the air is discharged through an exhaust port. In the existing robot cleaners, there is an inconvenience that a portion of a cleaner body should be disassembled so as to replace or clean the HEPA filter. 
     Various robot cleaners are described in the following documents: 
     Patent Document 1: U.S. Pat. Laid-Open Publication No. US 2013/0305484 A1 (published on Nov. 21, 2013); 
     Patent Document 2: U.S. Pat. Laid-Open Publication No. US 2013/0061420 A1 (published on Mar. 14, 2013); and 
     Patent Document 3: U.S. Pat. Laid-Open Publication No. US 2013/0061417 A1 (published on Mar. 14, 2013). 
     The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments will be described in detail with reference to the following drawings in which like reference numerals refer to like elements wherein: 
         FIG.  1    is a perspective view illustrating an example of a robot cleaner according to an embodiment; 
         FIG.  2    is a plan view of the robot cleaner shown in  FIG.  1   ; 
         FIG.  3    is a side view of the robot cleaner shown in  FIG.  1   ; 
         FIG.  4    is a view illustrating a sensing unit shown in  FIG.  1   ; 
         FIG.  5    is an exploded perspective view of the sensing unit shown in  FIG.  4   ; 
         FIG.  6    is a view illustrating a section of the sensing unit shown in  FIG.  4   ; 
         FIG.  7    is a view illustrating separation of an image photographed by a first sensing part shown in  FIG.  6   ; 
         FIG.  8    illustrates sensing of an obstacle by a second sensing part shown in  FIG.  4   ; 
         FIG.  9    is a block diagram illustrating main parts related to avoidance of an obstacle using the second sensing part; 
         FIG.  10    is a view illustrating a beam irradiation range of first and second pattern irradiating parts and an obstacle detection range of an image acquisition part; 
         FIG.  11    is a view illustrating a beam having a first pattern, irradiated by the first pattern irradiating part; 
         FIG.  12    is a view illustrating shapes of first and second beam patterns irradiated onto each obstacle for each shape of the obstacle. 
         FIG.  13    is a view illustrating a suction unit shown in  FIG.  1   ; 
         FIG.  14    is a side view of the suction unit shown in  FIG.  13   ; 
         FIG.  15    is a front view of the suction unit shown in  FIG.  13   ; 
         FIG.  16    is a view illustrating a bottom portion of the suction unit shown in  FIG.  13   ; 
         FIG.  17    illustrates a brush roller protruding through a manipulation of a manipulation part in the suction unit shown in  FIG.  13   ; 
         FIG.  18    illustrates a flow of air inside the robot cleaner shown in  FIG.  1   ; 
         FIG.  19    is a view illustrating a state in which a dust container is mounted in a dust container accommodation part in the robot cleaner shown in  FIG.  1   ; 
         FIG.  20    is a view illustrating the dust container shown in  FIG.  1   ; 
         FIG.  21    is an exploded perspective view illustrating main parts of the dust container illustrated in  FIG.  20   ; 
         FIG.  22    is a bottom view of the dust container shown in  FIG.  20   ; 
         FIG.  23    is a view illustrating a state in which the dust container is mounted in the dust container accommodation part shown in  FIG.  19   ; 
         FIG.  24    is a front view of the dust container shown in  FIG.  20   ; 
         FIGS.  25  and  26    are perspective views of a flow separation member illustrated in  FIG.  24   , viewed from different directions; 
         FIG.  27    is a sectional view taken along the line A-A of  FIG.  24   ; 
         FIG.  28    is a left side view of the dust container of  FIG.  20   ; 
         FIG.  29    is a view illustrating the dust container of  FIG.  20   , excluding the upper case; 
         FIG.  30    is a view illustrating a state in which an upper case and an upper cover are separated from the dust container shown in  FIG.  20   ; 
         FIG.  31    is a view illustrating a dust container cover shown in  FIG.  1   ; 
         FIG.  32    is an exploded perspective view of the dust container cover shown in  FIG.  31   ; 
         FIG.  33    is a view illustrating a rear surface of the dust container cover shown in  FIG.  31   ; 
         FIG.  34    is a sectional view illustrating a structure in which a hook part shown in  FIG.  33    is fastened to the dust container; 
         FIG.  35    is a view illustrating an inside of the dust container accommodation part shown in  FIG.  19   ; 
         FIG.  36    is a view illustrating a state in which a filter unit shown in  FIG.  35    is rotated; and 
         FIG.  37    is an exploded perspective view of the filter unit shown in  FIG.  36   . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS.  1  to  3   , the robot cleaner  100  cleans a floor while traveling autonomously in a certain area. The cleaning of the floor includes sucking foreign substances, e.g., debris, dust, fine dust, ultrafine dust, etc., of the floor or mopping the floor. The robot cleaner  100  includes a cleaner body  110 , a suction unit  120  (e.g. cleaner head), a sensing unit or module  130 , and a dust container  140 . The cleaner body  110  is provided with a controller for controlling the robot cleaner  100  and wheels  111  for allowing the robot cleaner  100  to travel. The robot cleaner  100  may be moved in all directions or be rotated by the wheels  111 . 
     The wheels  111  includes main wheels  111   a  and a sub-wheel  111   b . The main wheels  111   a  are provided at both sides of the cleaner body  110  to be rotatable in one direction or the other direction according to a control signal of the controller. The main wheels  111   a  may be configured to be driven independently from each other. For example, the main wheels  111   a  may be driven by different driving motors, respectively. The sub-wheel  111   b  supports the cleaner body  110  together with the main wheels  111   a , and is configured to assist traveling of the robot cleaner  100  through the main wheels  111   a . The sub-wheel  111   b  may also be provided in the suction unit  120 . The controller controls the driving of the wheels  111 , such that the robot cleaner  100  autonomously travels on the floor. 
     A battery  180  ( FIG.  18   ) supplies power to the robot cleaner  100  and is mounted in the cleaner body  110 . The battery  180  is rechargeable and may be configured to be attachable/detachable to/from a bottom surface of the cleaner body  110 . 
     The suction unit  120  is provided in a shape protruding from one side of the cleaner body  110  to suck air containing foreign substances. The one side may be a side at which the cleaner body  110  travels in a forward direction F, i.e., the front of the cleaner body  110 . The suction unit  120  may have a shape protruding frontward, leftward, and rightward at the one side of the cleaner body  110 . A front end portion of the suction unit  120  may be provided at a position spaced apart forward from the one side of the cleaner body  110 , and both left and right end portions of the suction unit  120  are provided at positions spaced apart leftward and rightward from the one side of the cleaner body  110 , respectively. 
     As the cleaner body  110  is formed in a circular shape, and both sides of a rear end portion of the suction unit  120  are respectively formed to protrude leftward and rightward from the cleaner body  110 , empty spaces, i.e., gaps may be formed between the cleaner body  110  and the suction unit  120 . The empty spaces are spaces between both left and right end portions of the cleaner body  110  and both left and right end portions of the suction unit  120 , and have a shape recessed inward of the robot cleaner  100 . 
     When an obstacle is inserted into the empty space, a problem may occur where the robot cleaner  100  is caught by the obstacle and may stop movement. In order to prevent this problem, a cover member  129  or a flap of a plate or wedge shape may be provided to cover at least one portion of the empty space. The cover member  129  may be provided to the cleaner body  110   or the suction unit  120 . In this embodiment, the cover members  129  may protrude from both sides of the rear end portion of the suction unit  120  to cover outer circumferential surfaces of the cleaner body  110 , respectively. 
     The cover members  129  are provided to fill in the empty space, i.e., at least one portion of the empty spaces between the cleaner body  110  and the suction unit  120 . The cover member  129  is provided to fill in at least one portion of spaces recessed inward between left and right outer circumferential surfaces of the cleaner body  110  formed in a curve and both left and right end portions of the suction unit  120  formed to protrude from the respective left and right outer circumferential surfaces. The structure of the cover member  129  may prevent an obstacle from being caught in the empty space or may allow escape from an obstacle even when the obstacle is caught in the empty space. 
     The cover member  129  formed to protrude from the suction unit  120  may be supported by the outer circumferential surface of the cleaner body  110 . When the cover member  129  is formed to protrude from the cleaner body  110 , the cover member  129  may be supported by a rear surface portion of the suction unit  120 . When the suction unit  120  collides with an obstacle and receives an impact from the obstacle, a portion of the impact is transferred to the cleaner body  110 , such that the force of impact may be distributed. 
     The suction unit  120  may be detachably coupled to the cleaner body  110 . The suction unit  120  may be swapped with a mop module. When a user intends to remove dust of a floor, the user may mount the suction unit  120  to the cleaner body  110 . When the user intends to mop the floor, the user may mount the mop module to the cleaner body  110 . 
     When the suction unit  120  is mounted to the cleaner body  110 , the mounting may be guided by the cover members  129 . The cover members  129  are provided to cover the outer circumferential surface of the cleaner body  110  such that a relative position of the suction unit  120  with respect to the cleaner body  110  can be determined and/or aligned. 
     The sensing unit  130  (sensor module) is provided at the cleaner body  110 . The sensing unit  130  may be provided at one side of the cleaner body  110 , i.e., the front of the cleaner main body  110 . The sensing unit  130  may protrude from top and side surfaces of the cleaner body  110 , and an upper end  134   b   1  ( FIG.  5   ) of the sensing unit  130  is formed at a position protruding upward from the top surface of the cleaner body  110 . 
     The sensing unit  130  may be provided to overlap with the suction unit  120  in the top-bottom direction of the cleaner body  110 . The sensing unit  130  is provided above the suction unit  120  to sense an obstacle and/or geographic feature at the front thereof such that the suction unit  120  located foremost of the robot cleaner  100  does not collide with the obstacle and/or geographic feature. The sensing unit  130  is configured to additionally perform another sensing function other than a sensing function, which will be described in detail hereinafter. 
     A dust container accommodation part  113  (recess) is provided in the cleaner body  110 , and the dust container  140  that separates and collects foreign substances of the sucked air is detachably coupled to the dust container accommodation part  113 . The dust container accommodation part  113  may be formed at the other side of the cleaner body  110 , e.g., the rear of the cleaner body  110 . The dust container accommodation part  113  has a shape opened rearward and upward from the cleaner body  110 . The dust container accommodation part  113  may be formed in a shape dented toward rear and front sides of the cleaner body  110 . 
     A portion or front of the dust container  140  is accommodated in the dust container accommodation part  113 . In this case, the other portion or rear of the dust container  140  may be formed to protrude toward the rear of the cleaner body  110  (i.e., in a reverse direction R opposite to the forward direction F). 
     An entrance  140   a  (see  FIG.  20   ) through which air containing dust is introduced and an exit  140   b  (see  FIG.  20   ) through which air having dust separated therefrom is discharged are formed in the dust container  140 . When the dust container  140  is mounted in the dust container accommodation part  113 , the entrance or inlet  140   a  and the exit or outlet  140   b  are configured to respectively communicate with a first opening  110   a  (see  FIG.  19   ) and a second opening  110   b  (see  FIG.  19   ), which are formed in an inner wall of the dust container accommodation part  113 . 
     An intake flow path in the cleaner body  110  corresponds to a flow path from an introduction port  110 ′ communicating with a communication part  120   b ″ to the first opening  110   a , and an exhaust flow path in the cleaner body  110  corresponds to a flow path from the second opening  110   b  to an exhaust port  112 . See  FIG.  18   . 
     According to such an air flow connection relationship, air containing foreign substances, which is introduced through the suction unit  120 , is introduced into the dust container  140  via the intake flow path in the cleaner body  110 , and the foreign substances are separated from the sucked air by passing through at least one cyclone provided in the dust container  140 . The foreign substances, e.g., dust is collected in the dust container  140 , and the air is discharged from the dust container  140 . The filtered air is discharged to the outside through the exhaust port  112  by passing through the exhaust flow path in the cleaner body  110 . 
     Referring to  FIGS.  4  to  6   , the sensing unit  130  includes a first sensing part  131  and a second sensing part  132 . The first sensing part  131  (first image sensor) is provided inclined with respect to one surface of the cleaner body  110  to simultaneously photograph front and upper parts of the cleaner body  110 . A camera may be used as the first sensing part  131 . The camera may be inclined relative to a floor surface as a surface parallel to the floor, or the top or side surface of the cleaner body  110 . For example, the first sensing part  131  may be provided inclined at 30 degrees with respect to the top surface of the cleaner body  110 . 
     The first sensing part  131  may be located at an upper corner portion at which the top and side surfaces of the cleaner body  100  meet each other. For example, the first sensing part  131  may be provided at a middle upper corner portion of the cleaner body  110  to be inclined with respect to each of the top and side surfaces of the cleaner body  110 . As the first sensing part  131  is provided inclined within a range of acute angles with respect to the one surface of the cleaner body  110 , the sensing part  131  is configured to simultaneously photograph the front and upper parts of the cleaner body  110 . 
       FIG.  7    in conjunction with  FIG.  6    illustrates an image photographed by the first sensing part  131 , which is divided into a front image A and an upper image B. The front image A and the upper image B, may be divided based on an angle α of view (field of view) in the top and bottom direction) of the first sensing part  131 . An image corresponding to a portion α1 of the angle α of view in the photographed image A+B may be recognized as the front image A, and an image corresponding to the other portion α2 of the angle α of view in the photographed image A+B may be recognized as the upper image B. As shown in  FIG.  6   , the angle α of view may be an obtuse angle. 
     The front image A photographed by the first sensing part  131  is used to monitor the front in real time. For example, when the robot cleaner  100  is used for household purposes, the front image A photographed by the first sensing part  131  may be used for monitoring or to provide an image of the inside of the house to an electronic device (e.g., a mobile terminal possessed by the user) through a remote connection. 
     When the front image A photographed by the first sensing part  131  is used for monitoring a house, the following control or operational mode may be performed. The controller may compare fronts images A photographed by the first sensing part  131  at a preset time interval. When the front images A are different from each other, the controller may generate a control signal. The control may be performed in a state in which the cleaner body  110  is stationary. The control signal may be an alarm sound output signal or a transmission signal that provides a notification, a photographed front image, and the like to the electronic device through the remote connection. 
     When the front image A photographed by the first sensing part  131  is used to provide an image of the inside of the house to the electronic device, the following control or operational mode may be performed. When an image request signal is received by the robot cleaner from the electronic device through the remote connection, the controller may ascertain a front image A from an image photographed by the first sensing part  131  and transmit the front image A to the electronic device. The robot cleaner may be configured to move to a specific position by controlling driving of the wheel unit  111  and then transmit a front image at the corresponding position to the electronic device. 
     As shown in  FIG.  6   , the angle α of view may have a range in which the first sensing part  131  can photograph the upper image B including a ceiling. The upper image B photographed by the first sensing part  131  is used to generate a map of a traveling area and sense or determine a current position in the traveling area. For example, when the robot cleaner  100  is used for household purposes, the controller may generate a map of a traveling area, using a boundary between a ceiling and a side surface in the upper image B photographed by the first sensing part  131 , and sense or determine a current position in the traveling area based on main feature points of the upper image B. The controller may use both upper image B and the front image A to generate a map of a traveling area and sense or determine a current position in the traveling area. 
     The second sensing part  132  (second sensor) is provided in a direction intersecting the first sensing part  131  to sense an obstacle or geographic feature located at the front thereof. The second sensing part  132  may be provided along the top-bottom direction at the side surface of the cleaner body  110 . The second sensing part  132  includes a first pattern irradiating part or a first light source  132   a , a second pattern irradiating part or a second light source  132   b , and an image acquisition part or an image sensor  132   c . 
     The first pattern irradiating part  132   a  is configured to irradiate a beam having a first pattern toward a front lower side or front bottom direction of the robot cleaner  100 , and the second pattern irradiating part  132   b  is configured to irradiate a beam having a second pattern toward a front upper side or front upper direction of the robot cleaner  100 . The first pattern irradiating part  132   a  and the second pattern irradiating part  132   b  may be provided in a line along the top-bottom direction of the cleaner body. As an example, the second pattern irradiating part  132   b  is provided under or below the first pattern irradiating part  132   a . 
     The image acquisition part or second image sensor  132   c  is configured to photograph, in a preset photographing area, the beams having the first and second patterns, which are respectively irradiated by the first pattern irradiating part  132   a  and the second pattern irradiating part  132   b . The preset photographing area includes an area from the floor to an upper end of the robot cleaner  100 . The robot cleaner  100  may sense or detect an obstacle at the front thereof, and it is possible to prevent the robot cleaner  100  from colliding with an upper portion of the cleaner body being stuck or colliding with an obstacle. 
     The preset photographing area may be, for example, an area within an angle of view of 105 degrees in the top-bottom direction (i.e., the vertical direction), an angle of view of 135 degrees in the left-right direction (i.e., the horizontal direction), and the front of 25 m relative to the cleaner body. The preset photographing area may be changed depending on various factors such as installation positions of the first and second pattern irradiating parts  132   a  and  132   b , irradiation angles of the first and second pattern irradiating parts  132   a  and  132   b , and a height of the robot cleaner  100 . 
     The first pattern irradiating part  132   a , the second pattern irradiating part  132   a , and the image acquisition part  132   c  may be provided in a line along the top-bottom direction of the cleaner body  110 . As illustrated, the image acquisition part  132   c  is provided under the second pattern irradiating part  132   b . The first pattern irradiating part  132   a  is provided to be downwardly inclined with respect to the side surface of the cleaner body  110 , and the second pattern irradiating part  132   b  is provided to be upwardly inclined with respect to the side surface of the cleaner body  110 . 
     Referring to (a) of  FIG.  8   , the first pattern irradiating part  132   a  and the second pattern irradiating part  132   b  are configured to respectively irradiate beams having first and second patterns that have a shape extending at least one direction. As illustrated, the first pattern irradiating part  132   a  irradiates linear beams intersecting each other and the second pattern irradiating part  132   b  irradiates a single linear beam. Accordingly, a bottommost beam is used to sense an obstacle at a bottom portion, a topmost beam is used to sense an obstacle at a top portion, and a middle beam between the bottommost beam and the topmost beam is used to sense an obstacle at a middle portion. 
     For example, as shown in (b) of  FIG.  8   , when an obstacle O is located at the front, the bottommost beam and a portion of the middle beam may be interrupted or distorted by the obstacle O. When such interruption or distortion is sensed, the image acquisition part  132   c  transmits an obstacle sensing signal to the controller. 
     If the obstacle sensing signal is received, the controller determines that the obstacle O is located, and controls the driving of the wheel unit  111 . For example, the controller may apply a driving force in the opposite direction to the main wheels  111   a  such that the robot cleaner  100  moves rearward. Alternatively, the controller may apply the driving force to only any one of the main wheels  111   a  such that the robot cleaner  100  rotates, or apply the driving force to both the main wheels  111   a  in directions different from each other. 
       FIG.  9    is a block diagram illustrating main parts or components related to avoidance of an obstacle using the second sensing part  132 . The robot cleaner  100  includes the wheel unit  111 , a data part or storage device  191 , a second sensing part  132 , and a controller  190  that controls overall operations. 
     The controller  190  may include a traveling or movement controller  190   c  that controls the wheel unit  111 . As a left main wheel  111   a  and a right main wheel  111   a  are independently driven by the traveling controller  190   c , the robot cleaner  100  may move in a straight direction or rotate left or right. A driving motor of which driving is controlled according to a control command of the traveling controller  190   c  may be connected to each of the left main wheel  111   a  and the right main wheel  111   a . 
     The controller  190  may include a pattern detection part or pattern detector  190   a  that detects a pattern by analyzing data input from the second sensing part  132  and an obstacle information acquisition part or module  190   b  that determines whether an obstacle exists from the detected pattern. The pattern detection part  190   a  detects beam patterns P 1  and P 2  from an image (acquired image) acquired by the image acquisition part  132 . The pattern detection part  190   a  may detect features of points, lines, surfaces, and the like with respect to predetermined pixels constituting the acquired image, and detect the beam patterns P 1  and P 2  or points, lines, surfaces, and the like, which constitute the beam patterns P 1  and P 2 . The obstacle information acquisition part  190   b  determines whether an obstacle exists based on the patterns detected from the pattern detection part  190   a , and determine a shape of the obstacle. 
     The data part  191  stores reference data that stores an acquired image input from the second sensing part  132  and allows the obstacle information acquisition part  190   b  to determine whether an obstacle exists. The data part  191  stores obstacle information on a sensed obstacle. The data part  191  stores control data for controlling an operation of the robot cleaner  100  and data corresponding to a cleaning mode of the robot cleaner  100 . The data part  191  stores a map generated or received from the outside. In addition, the data part  191  stores data readable by a microprocessor, and may include a hard disk driver (HDD), a solid state disk (SSD), a silicon disk drive (SDD), a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, and an optical data storage device. 
     The second sensing part  132  includes the first pattern irradiating part  132   a , the second pattern irradiating part  132   b , and the image acquisition part  132   c . The second sensing part  132  is installed at a front side of the cleaner body  110 . In the second sensing part  132 , the first and second pattern irradiating parts  132   a  and  132   b  irradiate beams P 1  and P 2  having first and second patterns toward the front of the robot cleaner  100 , and the image acquisition part  132   c  acquires an image by photographing the irradiated beams having the patterns. 
     The controller  190  stores an acquired image in the data part  191 , and the pattern detection part  190   a  extracts a pattern by analyzing the acquired image. The pattern detection part  190   a  extracts a beam pattern obtained by irradiating a beam having a pattern, which is irradiated from the first pattern irradiating part  132   a  or the second pattern irradiating part  132   b , onto a floor or obstacle. The obstacle information acquisition part  190   b  determines whether an obstacle exists, based on the extracted beam pattern. 
     The controller  190  determines whether an obstacle exists through an acquired image input from the second sensing part  132  and controls the wheel unit  111  to travel while avoiding the obstacle by changing a moving direction or traveling route. 
     When a cliff (e.g., stairs) exists in the vicinity of the robot cleaner  100 , the robot cleaner  100  may fall from the cliff. The controller  190  may sense the cliff through an acquired image, and reconfirm whether the cliff exists through a cliff sensor  124 , to control the traveling of the robot cleaner  100  such that the robot cleaner  100  does not fall from the cliff. When it is determined that a cliff does exist, the controller  190  may control the wheel unit  111  to travel along the cliff by determining a change in beam pattern through an acquired image. 
     In addition, when the movement of the robot cleaner  100  may be restricted due to a plurality of obstacles existing in an area having a certain size or less, the controller  190  may determine whether the robot cleaner  100  is in a restricted situation, and set an escape mode such that the robot cleaner  100  avoids the restricted situation. The controller  190  may allow the robot cleaner  100  to avoid the restricted situation by setting an escape route based on information on each obstacle around the robot cleaner  100  according to whether a currently set mode is a fundamental mode or a fast cleaning mode. 
     For example, in the fundamental mode, the controller  190  may generate a map on a peripheral area by acquiring information on all obstacles around the robot cleaner  100  and then set an avoidance route. In the fast cleaning mode, the controller  190  may set an avoidance route by determining whether the robot cleaner  100  is to enter according to a distance between sensed obstacles. 
     The controller  190  determines a distance between sensed obstacles by analyzing a beam pattern of an acquired image with respect to the sensed obstacles, and determines that the robot cleaner  100  is to travel and enter when the distance between the obstacles is a certain value or more, to control the robot cleaner  100  to travel. Thus, the controller  190  enables the robot cleaner  100  to escape a restricted situation. 
       FIG.  10    is a view illustrating a beam irradiation range of the first and second pattern irradiating parts  132   a  and  132   b  and an obstacle detection range of the image acquisition part  132   c . Each of the first and second pattern irradiating parts  132   a  and  132   b  may include a beam source and an optical pattern projection element (OPPE) that generates a beam having a predetermined pattern as a beam irradiated from the beam source is transmitted therethrough. 
     The beam source may be a laser diode (LD), a light emitting diode (LED), or the like. Since a laser beam has characteristics of monochromaticity, straightness, and connectivity, the laser diode is superior to other beam sources, and thus can accurately measure a distance. In particular, since an infrared or visible ray has a large variation in accuracy of distance measurement depending on factors such as a color and a material of an object, the laser diode is used as the beam source. 
     A pattern generator may include a lens and a diffractive optical element (DOE). Beams having various patterns may be irradiated according to a configuration of a pattern generator provided in each of the first and second pattern irradiating parts  132   a  and  132   b . The first pattern irradiating part  132   a  may irradiate a beam P 1  having a first pattern (hereinafter, referred to as a first pattern beam) toward a front lower side of the cleaner body  110 . The first pattern beam P 1  may be incident onto a floor of a cleaning area. The first pattern beam P 1  may be formed in the shape of a horizontal line. The first pattern beam P 1  may be formed in the shape of a cross pattern in which a horizontal line and a vertical line intersect each other. 
     The first pattern irradiating part  132   a , the second pattern irradiating part  132   b , and the image acquisition part  132   c  may be vertically aligned. As illustrated, the image acquisition part  132   c  is provided under the first pattern irradiating part  132   a  and the second pattern irradiating part  132   b . However, the present disclosure is not necessarily limited thereto, and the image acquisition part  132   c  may be provided above the first pattern irradiating part  132   a  and the second pattern irradiating part  132   b . 
     The first pattern irradiating part  132   a  may also sense an obstacle located lower than the first pattern irradiating part  132   a  by downwardly irradiating the first pattern beam P 1  toward the front, and the second pattern irradiating part  132   b  may be located at a lower side of the first pattern irradiating part  132   a  to upwardly irradiate a beam P 2  having a second pattern (hereinafter, referred to as a second pattern beam) toward the front. The second pattern beam P 2  may be incident onto an obstacle or a certain portion of the obstacle, which is located higher than at least the second pattern irradiating part  132   b  from the floor of the cleaning area. The second pattern beam P 2  may have a pattern different from that of the first pattern beam P 1 , and may be configured to include a horizontal line. The horizontal line is not necessarily a consecutive line segment but may be formed as a dotted line. 
     Meanwhile, a horizontal irradiation angle of the first pattern beam P 1  irradiated from the first pattern irradiating part  132   a  (e.g., an angle made by both ends of the first pattern beam P 1  and the first pattern irradiating part  132   a ) may be defined in a range of 130 degrees to 140 degrees, but the present disclosure is not necessarily limited thereto. The first pattern beam P 1  may be formed in a shape symmetrical with respect to the front of the robot cleaner  100 . 
     Like the first pattern irradiation part  132   a , a horizontal irradiation angle of the second pattern irradiating part  132   b  may be defined in a range of 130 degrees to 140 degrees. In some other embodiments, the second pattern irradiating part  132   b  may irradiate the second pattern beam P 2  at the same horizontal irradiation angle as the first pattern irradiating part  132   a . In this case, the second pattern beam P 2  may also be formed in a shape symmetrical with respect to the front of the robot cleaner  100 . 
     The image acquisition part  132   c  may acquire an image of the front of the cleaner body  110 . The pattern beams P 1  and P 2  are shown in an image acquired by the image acquisition part  132   c  (hereinafter, referred to as an acquired image). Hereinafter, images of the pattern beams P 1  and P 2  shown in the acquired image are referred to as beam patterns. Since the beam patterns are images formed as the pattern beams P 1  and P 2  incident onto an actual space are formed in an image sensor, the beam patterns are designated by the same reference numerals as the pattern beams P 1  and P 2 . Images corresponding to the first pattern beam P 1  and the second pattern beam P 2  are referred to as a first beam pattern P 1  and a second beam pattern P 2 , respectively. 
     The image acquisition part  132  may include a digital image acquisition part that converts an image of a subject into an electrical signal and then converts the electrical signal into a digital signal to be stored in a memory device. The digital image acquisition part may include an image sensor and an image processing part or processor. 
     The image sensor is a device that converts an optical image into an electrical signal, and is configured as a chip having a plurality of photo diodes integrated therein. An example of the photo diode may be a pixel. Electric charges are accumulated in each of the pixels by an image formed in the chip through a beam passing through a lens. The electric charges accumulated in the pixel are converted into an electric signal (e.g., a voltage). A charge coupled device (CCD), a complementary metal oxide semiconductor (CMOS), and the like are well known as the image sensor. 
     The image processing part generates a digital image, based on an analog signal output from the image sensor. The image processing part may include an AD converter that converts an analog signal into a digital signal, a buffer memory that temporarily records digital data according to the digital signal output from the AD converter, and a digital signal processor (DSP) that generates a digital image by processing the data recorded in the buffer memory. 
     The pattern detection part  190   a  may detect features of points, lines, surfaces, and the like with respect to predetermined pixels constituting an acquired image, and detect the beam patterns P 1  and P 2  or points, lines, surfaces, and the like, which constitute the beam patterns P 1  and P 2 . For example, the pattern detection part  190   a  may extract a horizontal line constituting the first beam pattern P 1  and a horizontal line constituting the second beam pattern P 2  by extracting line segments configured as pixels brighter than surroundings are consecutive. However, the present disclosure is not limited thereto. Since various techniques of extracting a pattern having a desired shape from a digital image have already been well known in the art, the pattern detection part  190   a  may extract the first beam pattern P 1  and the second beam pattern P 2  using these techniques. 
     The first pattern irradiating part  132   a  and the second pattern irradiating part  132   b  are vertically provided to be spaced apart from each other at a distance h3. The first pattern irradiating part  132   a  downwardly irradiates a first pattern beam, and the second pattern irradiating part  132   b  upwardly irradiates a second pattern beam, so that the first and second pattern beams intersect each other. 
     The image acquisition part  132   c  is provided downward from the second pattern irradiating part  132   b  at a distance h2 to photograph an image of the front of the cleaner body  110  at an angle θs of view with respect to the top-bottom direction. The image acquisition part  132   c  is installed at a position spaced apart from the bottom surface at a distance h1. The image acquisition part  132   c  may be preferably installed at a position that does not interfere with the photographing of an image of the front, by considering the shape of the suction unit  120 . 
     Each of the first pattern irradiating part  132   a  and the second pattern irradiating part  132   b  is installed such that a direction in which the direction of optical axes of lenses constituting each of the first pattern irradiating part  132   a  and the second pattern irradiating part  132   b  forms a certain irradiation angle. 
     The first pattern irradiating part  132   a  downwardly irradiates the first pattern beam P 1  at a first irradiation angle θr1, and the second pattern irradiating part  132   b  upwardly irradiates the second pattern beam P 2  at a second irradiation angle θr2. The first irradiation angle θr1 and the second irradiation angle θr2 are basically different from each other, but may be set equal to each other in some cases. The first irradiation angle θr1 and the second irradiation angle θr2 may be preferably set in a range of 50 degrees to 75 degrees, but the present disclosure is not necessarily limited thereto. For example, the first irradiation angle θr1 may be set to 60 degrees to 70 degrees, and the second irradiation angle θr2 may be set to 50 degrees to 55 degrees. The first irradiation angle θr1 and the second irradiation angle θr2 may be changed depending on the shape of the suction unit  120  and the height of an upper portion to be sensed. 
     When a pattern beam irradiated from the first pattern irradiating part  132   a  and/or the second pattern irradiating part  132   b  is incident onto an obstacle, the positions of the beam patterns P 1  and P 2  in an acquired image may be changed depending on a position at which the obstacle is distant from the first pattern irradiating part  132   a . For example, when the first pattern beam P 1  and the second pattern beam P 2  are incident onto a predetermined obstacle, the first beam pattern P 1  is displayed at a higher position in the acquired image as the obstacle is located closer to the robot cleaner  100 . On the contrary, the second beam pattern P 2  is displayed at a lower position in the acquired image as the obstacle is located more distant from the robot cleaner  100 . 
     Data on distances to an obstacle, which correspond to rows (lines configured with pixels arranged in the lateral direction) constituting an image generated by the image acquisition part  132   c , is stored in advance. If the beam patterns P 1  and P 2  detected in the image acquired through the image acquisition part  132   c  are detected on a predetermined row, a position of the obstacle may be estimated from data on a distance to the obstacle, which corresponds to the row. The angle θs of view of the image acquisition part  132   c  may be set to a value of 100 degrees or more, and be preferably set to 100 degrees to 110 degrees. However, the present disclosure is not necessarily limited thereto. 
     In addition, the distance from the floor of the cleaning area to the image acquisition part  132   c  may be set to about 60 mm to 70 mm. In this case, the floor of the cleaning area in the image acquired by the image acquisition part  132   c  is shown posterior to D1 from the image acquisition part  132   c , and D2 is a position at which the first beam pattern P 1  is displayed on the floor shown in the acquired image. 
     When an obstacle is located in D2, an image in which the first beam pattern P 1  is incident onto the obstacle may be acquired by the image acquisition part  132   c . When the obstacle comes closer to the robot cleaner  100  than D2, the first optical pattern is displayed upward of a reference position ref1, corresponding to the incident first pattern beam P 1 . 
     The distance from the cleaner body  110  to D1 may be 100 mm to 150 mm, and the distance from the cleaner body  110  to D2 may be preferably 180 mm to 280 mm. However, the present disclosure is not necessarily limited thereto. Meanwhile, D3 represents a distance from a most protruding portion of the front of the cleaner body  110  to a position at which the second pattern beam is incident. Since the cleaner body  110  senses an obstacle during traveling, D3 is a minimum of distance at which the cleaner body  110  can sense the obstacle at the front (upper portion) thereof without colliding with the obstacle. D3 may be set to about 23 mm to 30 mm. 
     When the first beam pattern P 1  shown in an acquired image disappears in a normal state during traveling of the cleaner body  110  or when a portion of the first beam pattern is displayed in the acquired image, the obstacle information acquisition part  190   b  determines that a cliff exists in the vicinity of the robot cleaner  100 . 
     When the first beam pattern P 1  is not displayed in the acquired image, the obstacle information acquisition part  190   b  may recognize that a cliff exists at the front of the robot cleaner  100 . When a cliff (e.g., stairs) exists at the front of the robot cleaner  100 , the first pattern beam is not incident onto the floor, and therefore, the first beam pattern P 1  disappears in the acquired image. 
     The obstacle information acquisition part  190   b  may determine that a cliff exists at the front distant by D2 from the cleaner body  110 , based on a length of D2. In this case, when the first beam pattern P 1  has a cross shape, the horizontal line disappears and only the vertical line is displayed. Therefore, the obstacle information acquisition part  190   b  may determine that a cliff exists. 
     In addition, when a portion of the first beam pattern is not displayed, the obstacle information acquisition part  190   b  may determine that a cliff exists at the left or right side of the robot cleaner  100 . When a right portion of the first beam pattern is not displayed, the obstacle information acquisition part  190   b  may determine that a cliff exists at the right side of the robot cleaner  100 . Based on detected information on a cliff, the obstacle information acquisition part  190   b  can control the wheel unit  111  to travel along a route on which the robot cleaner  100  does not fall from the cliff. 
     When a cliff exists at the front of the robot cleaner  100 , the traveling controller  190   c  may again check whether a cliff exists, using a cliff sensor installed at a lower portion of the cleaner body  110 , by moving forward by a certain distance, e.g., D2 or less. The robot cleaner  100  can primarily check whether a cliff exists through an acquired image and secondarily check whether a cliff exists through the cliff sensor. 
       FIG.  11    is a view illustrating a beam having a first pattern, irradiated by the first pattern irradiating part  132   a . The pattern detection part  190   a  detects a first beam pattern or a second beam patter from an acquired image input from the image acquisition part  132   c  and applies the first or second beam pattern to the obstacle information acquisition part  190   b . The obstacle information acquisition part  190   b  analyzes the first or second beam pattern detected from the acquired image and compares a position of the first beam pattern with the reference position ref1, thereby determining whether an obstacle exists. 
     As shown in (a) of  FIG.  11   , when the horizontal line of the first beam pattern P 1  is located at the reference position ref1, the obstacle information acquisition part  190   b  determines that a current state is a normal state. The normal state is a state in which the floor is even and flat, and is a state in which the robot cleaner  100  can continuously travel as any obstacle does not exist at the front of the robot cleaner. 
     The second beam pattern P 2  is incident onto an obstacle only when the obstacle exists at an upper portion of the front to be displayed in an acquired image. The second beam pattern P 2  is not generally displayed in the acquired image in the normal state. 
     As shown in (b) of  FIG.  11   , when the horizontal line of the first beam pattern P 1  is located above the reference position ref1, the obstacle information acquisition part  190   b  determines that an obstacle exists at the front. If an obstacle is detected through the obstacle information acquisition part  190   b  as described above, the traveling controller  190   c  controls the wheel unit  111  to travel while avoiding the obstacle. Meanwhile, the obstacle information acquisition part  190   b  may determine the position and size of the sensed obstacle, corresponding to the positions of the first and second beam patterns P 1  and P 2  and whether the second beam pattern P 2  has been displayed. In addition, the obstacle information acquisition part  190   b  may determine the position and size of the obstacle, corresponding to changes of the first and second beam patterns P 1  and P 2  displayed in the acquired image during traveling. 
     The traveling controller  190   c  controls the wheel unit  111  by determining whether the wheel unit  111  is to continuously travel with respect to the obstacle or to travel while avoiding the obstacle, based on information of the obstacle, which is input from the obstacle information acquisition part  190   b . For example, when the height of the obstacle is lower than a certain height or less or when the cleaner body  110  is to enter into a space between the obstacle and the floor, the traveling controller  190   c  determines that the traveling of the wheel unit  111  is possible. 
     As shown in (c) of  FIG.  11   , the first beam pattern P 1  may be displayed at a position lower than the reference position ref1. When the first beam pattern P 1  may be displayed at a position lower than the reference position ref1, the obstacle information acquisition part  190   b  determines that a downhill road exists. In the case of a cliff, the first beam pattern P 1  disappears, and therefore, the downhill road is distinguished from the cliff. 
     As shown in (d) of  FIG.  11   , the obstacle information acquisition part  190   b  determines that a cliff exists in a traveling direction when the first beam pattern P 1  is not displayed. As shown in (e) of  FIG.  11   , when a portion of the first beam pattern P 1  is not displayed, the obstacle information acquisition part  190   b  may determines that a cliff exists at the left or right side of the cleaner body  110 . In this case, the obstacle information acquisition part  190   b  determines that a cliff exists at the left side of the cleaner body  110 . Meanwhile, when the first beam pattern P 1  has a cross shape, an obstacle may be determined by considering both the position of the horizontal line and the length of the vertical line. 
       FIG.  12    illustrates shapes of the first and second beam patterns P 1  and P 2  irradiated onto each obstacle for each shape of the obstacle. As beams irradiated from the first and second pattern irradiating parts  132   a  and  132   b  are incident onto an obstacle, so that beam patterns are shown in an acquired image, the obstacle information acquisition part  190   b  may determine the position, size, and shape of the obstacle. 
     As shown in (a) of  FIG.  12   , when a wall surface exists at the front during traveling of the cleaner body  110 , a first pattern beam is incident onto a floor and a second pattern beam is incident onto the wall surface. The first beam pattern P 1  and the second beam pattern P 2  are displayed as two horizontal lines in an acquired image. When a distance of the cleaner body  110  to the wall surface is longer than D2, the first beam pattern P 1  is displayed at the reference position ref1, but the second beam pattern P 2  is also displayed together with the first beam pattern P 1 . Therefore, the obstacle information acquisition part  190   b  may determine that an obstacle exists. 
     Meanwhile, when the distance of the cleaner body  110  to the wall surface is less than D2, the first pattern beam is incident onto the wall surface instead of the floor. Therefore, the first beam pattern P 1  is displayed at an upper side of the reference position ref1, and the second beam pattern P 2  is displayed at an upper side of the first beam pattern P 1 . Since the position of the second beam pattern P 2  is displayed at a lower side as the second beam pattern P 2  approaches the obstacle, the second beam pattern P 2  is displayed at a lower side as compared with when the distance of the cleaner body  110  to the wall surface is longer than D2. The second pattern beam P 2  is displayed at an upper side as compared with the reference position ref1 and the first beam pattern P 1 . Accordingly, the obstacle information acquisition part  190   b  can calculate a distance of the cleaner body  110  to the wall surface as an obstacle through the first beam pattern P 1  and the second beam pattern P 2 . 
     As shown in (b) of  FIG.  12   , when an obstacle such as a bed or a dresser exists, the first beam pattern P 1  and the second beam pattern P 2  are incident as two horizontal lines onto a floor and an obstacle, respectively. The obstacle information acquisition part  190   b  determines whether an obstacle exists, based on the first beam pattern P 1  and the second beam pattern P 2 . The height of the obstacle may be determined based on a position of the second beam pattern P 2  and a change of the second beam pattern P 2 , which occurs while the cleaner body  110  is approaching the obstacle. Accordingly, the traveling controller  190   c  controls the wheel unit  111  by determining whether the cleaner body  110  is to enter into a lower space of the obstacle. For example, when an obstacle having a predetermined space formed from the floor, such as a bed in a cleaning area, is located, the traveling controller  190   c  may recognize the space, and preferably determine whether to pass through or avoid the obstacle by detecting the height of the space. 
     When it is determined that the height of the space is lower than that of the cleaner body  110 , the traveling controller  190   c  may control the wheel unit  111  such that the cleaner body  110  travels while avoiding the obstacle. On the other hand, when it is determined that the height of the space is higher than that of the cleaner body  110 , the traveling controller  190  may control the wheel unit  111  such that cleaner body  110  enters into or passes through the space. 
     Although the first beam pattern P 1  and the second beam pattern P 2  are displayed as two horizontal lines even in (a) of  FIG.  12   , a distance between the first beam pattern P 1  and the second beam pattern P 2  in (b) of  FIG.  12    is different from that between the first beam pattern P 1  and the second beam pattern P 2  in (a) of  FIG.  12   . Therefore, the obstacle information acquisition part  190   b  may distinguish the difference. In (a) of  FIG.  12   , the position of the first beam pattern P 1  is displayed higher than the reference position ref1 as the first beam pattern approaches the obstacle. However, as shown in (b) of  FIG.  12   , when an obstacle is located above the cleaner body  110 , the first beam pattern P 1  is displayed at the reference position ref1 and the position of the second beam pattern P 2  is changed even when they approach the obstacle by a certain distance. The obstacle information acquisition part  190   b  may distinguish the kind of the obstacle. 
     As shown (c) of  FIG.  12   , in the case of a corner of an obstacle such as a bed or dresser, as the first beam pattern P 1  is irradiated as a horizontal line onto a floor, and the second beam pattern P 2  is irradiated onto the corner of the obstacle. As the second beam pattern P 2  is irradiated onto the corner of the obstacle, a portion of the second beam pattern P 2  is displayed as a horizontal line, and the other portion of the second beam pattern P 2  is displayed as an oblique line. Since the position of the second beam pattern P 2  becomes higher as the second beam pattern P 2  is more distant from the cleaner body  110 , the second beam pattern P 2  irradiated onto a side surface of the obstacle is displayed as an oblique line bent upward of the horizontal line irradiated onto a front surface of the obstacle. 
     As shown in (d) of  FIG.  12   , when the cleaner body  110  approaches a corner of a wall surface by a certain distance or more, a portion of the first beam pattern P 1  is displayed as a horizontal line at an upper side of the reference position ref1. As a portion of the second beam pattern P 2  is irradiated onto a side surface of the corner, the portion of the second beam pattern P 2  is displayed as an oblique line bent downward. As for a bottom surface, a portion of the second beam pattern P 2  is displayed as a horizontal line at the reference position ref1. 
     Meanwhile, a portion of the second beam pattern P 2  is displayed as a horizontal line as shown in (c) of  FIG.  12   , and a portion of the second beam pattern P 2 , which is irradiated onto the side surface of the corner, is displayed as an oblique line bent upward. 
     As shown in (e) of  FIG.  12   , in the case of an obstacle protruding from a wall surface, the first beam pattern P 1  is displayed as a horizontal line as the reference position ref1. A portion of the second beam pattern P 2  is displayed as a horizontal line on a protruding surface, another portion of the second beam pattern P 2  is displayed as an oblique line bent upward on a side surface of the protruding surface, and the other portion of the second beam pattern P 2  is displayed as a horizontal line on the wall surface. 
     Accordingly, the obstacle information acquisition part  190   b  can determine the position, shape, and size (height) of an obstacle, based on the positions and shapes of first and second pattern beams. 
     Additional details of the first sensor and second sensor are disclosed in U.S. Application Serial No. 15/597,333 filed on May 17, 2017 (Attorney Docket No. PBC-0602) or Korean Application No. 10-2016-0060444 filed May 17, 2016, and Korean Application No. 10-2016-0014116 filed on Oct. 27, 2016, whose entire disclosure is incorporated herein by reference. 
     Referring to  FIG.  5   , the sensing unit  130  further includes a window part or assembly  133  and a case  134 , in addition to the first sensing part  131  and the second sensing part  132 . The window part  133  is provided to cover the first and second sensing parts  131  and  132 , and has transparency. The transparency is a property that at least one portion of an incident beam is transmitted, and is translucent. 
     The window part  133  may be formed of a synthetic resin material or a glass material. When the window part  133  has the translucency, the material may be formed to have the translucency. Further, the material may have the transparency, and a film attached to the material may have the translucency. 
     The case  134  is mounted to the cleaner body  110 , and is configured to fix the first and second sensing parts  131  and  132  and the window part  133 . As shown in this figure, the case  134  is configured to accommodate at least one portion of the window part  133 . The case  134  may be formed of a synthetic resin material or a metallic material, and has opaqueness. 
     As shown in this figure, the case  134  may include a mounting frame  134   a  and the cover frame  134   b . The mounting frame  134   a  provides a space in which the first and second sensing parts  131  and  132  are mounted and supported. The mounting frame  134   a  may be provided with a first mounting part  134   a   1  (e.g., inclined protrusions) for mounting the first sensing part  131  thereto and a second mounting part  134   a   2  (e.g., tabs) for mounting the second sensing part  132  thereto. A board or a substrate  132 ′ on which the first and second pattern irradiating parts  132   a  and  132   b  and the image acquisition part  132   c  are mounted may be mounted to the second mounting part  134   a   2 . The second mounting part  134   a   2  may be provided inclined with respect to the first mounting part  134   a   1 . 
     The mounting frame  134   a  is provided with first and second fastening hooks  134   a ′ and  134   a ″ for allowing the mounting frame  134   a  to be fastened to the cover frame  134   b  and the window part  133 . The first fastening hook  134   a ′ is fastened to a fastening hole  134   b ′ of the cover frame  134   b , and the second fastening hook  134   a ″ is fastened to a fastening hole  133   b ″ of the window part  133 . The mounting frame  134   a  may be mounted to the cleaner body  110 . 
     The cover frame  134   b  is mounted to the cleaner body  110  in a state in which the cover frame  134   b  is coupled to the mounting frame  134   a  and accommodates at least one portion of the window part  133 . The cover frame  134   b  may be formed in an ‘L’ shape to cover top and side surfaces of the cleaner body  110  at a corner of the cleaner body  110 . 
     The upper end  134   b   1  of the cover frame  134   b  is located at an upper side of the first sensing part  131 , and may be formed inclined to have a sharp shape. According to the above-described shape, although the robot cleaner  100  is inserted into furniture or a gap during traveling thereof, the robot cleaner  100  can easily escape from the furniture or gap, and the first and second sensing parts  131  and  132  can be protected by the upper end  134   b   1  located upward of the first and second sensing parts  131  and  132 . In this figure, a case where the upper end  134   b   1  is formed at an end portion of a hole  134   b ″ which will be described later is illustrated as an example. 
     The first sensing part  131  and at least one portion of the second sensing part  132  may be accommodated in the hole  134   b ″ formed inside the cover frame  134   b . As illustrated, the first sensing part  131  and the first and second pattern irradiating parts  132   a  and  132   b  of the second sensing part  132  are accommodated in the hole  134   b ″. 
     The window part  133  may include a first window  133   a  and a second window  133   b . The first window  133   a  is formed of a transparent material, and is provided to cover the first sensing part  131 . The second window  133   b  is translucent, and is provided to cover the second sensing part  132 . As illustrated , a through-hole  133   b ′ may be formed at a portion of the second window part  133   b , which corresponds to the first sensing part  131 , and the first window  133   a  may be provided to cover the through-hole  133   b ′. 
     As the first window  133   a  is formed of a transparent material, images at the front and upper parts of the cleaner body  110  can be clearly photographed. Further, as the second window  133   b  is translucent, the first pattern irradiating part  132   a , the second pattern irradiating part  132   b , and the image acquisition part  132   c  on a rear surface of the second window  133   b  are not noticeable by the naked eye from the outside for a clean appearance. 
     The second window  133   b  may be divided in a first part  133   b   1  (first window cover), a second part  133   b   2  (second window cover), an extension part  133   b   4  (extension cover), and a third part  133   b   3  (third window cover). 
     The first part  133   b   1  is a part having the through-hole  133   b ′, and is provided inclined with respect to the top surface of the cleaner body  110 . The first window  133   a  mounted in the through-hole  133   b ′ is provided to cover the first sensing part  131 . 
     The second part  133   b   2  downwardly extends in an inclined shape from the first part  133   b   1 , and is provided to cover the first and second pattern irradiating parts  132   a  and  132   b . As illustrated, the second part  133   b   2  downwardly extends in parallel to the side surface of the cleaner body  110 . 
     The extension part  133   b   4  downwardly extends from the second part  133   b   2 , and is covered by the cover frame  134   b . As illustrated, the extension part  133   b   4  may downwardly extend toward the inside of the second part  133   b   2 . In other words, the extension part  133   b   4  may be provided upwardly inclined with respect to the third part  133   b   3  not to interfere with the angle of view in the top-bottom direction of the image acquisition part  132   c . Similarly, a portion of the cover frame  134   b , which covers the extension part  133   b   4 , is provided inclined not to interfere with the angle of view in the top-bottom direction of the image acquisition part  132   c . 
     The third part  133   b   3  downwardly extends from the extension part  133   b   4  to protrude outward of the cover frame  134   b , and is provided to cover the image acquisition part  132   c . The third part  133   b   3  may downwardly extend in parallel to the second part  133   b   2  along the side surface of the cleaner body  110 . 
     The suction unit  120  of  FIG.  1    will be described in more detail with reference to  FIGS.  13 - 16   . When the suction unit  120  has a shape protruding from the cleaner body  110 , it is likely that the suction unit  120  will collide with an obstacle unless a separate sensing unit is provided to the suction unit  120 . The sensing unit  130  provided to the cleaner body  110  senses an obstacle at the front of the suction unit  120 . 
     When an obstacle exists in a blind spot that the sensing unit  130  does not sense, a physical collision may occur between the robot cleaner  100  and the obstacle. When the physical collision occurs, the robot cleaner  100  is to move rearward or change a direction so as to avoid further collision with the obstacle. To avoid further collision, it is first required to sense the physical collision between the robot cleaner  100  and the obstacle. 
     The suction unit  120  includes a case  121  and a bumper switch  122  that senses the physical collision. The case  121  forms an appearance of the suction unit  120 , and includes an inlet port  120   b ′ that sucks air containing foreign substances, e.g., dust, and the communication part  120   b ″ (air outlet port of the suction unit  120 ) communicating with the inhalation flow path in the cleaner body  110 . At least one portion of the case  121  may have transparency such that the inside of the suction unit  120  may be viewable. The bumper switch  122  may be provided at at least one surface of the case  121 . When the bumper switch  122  in contact with an obstacle, the bumper switch  122  is pressurized to transmit a contact signal to the controller. The bumper switch  122  may be also provided to surround the case  121 . As illustrated, a front bumper switch  122   a  is provided at a front side of the case  121 , and side bumper switches  122   b  and  122   c  are provided at both left and right sides of the case  121 , respectively. It is possible to sense not only a physical collision with an obstacle located at the front of the suction unit  120  but also a physical collision of an obstacle located on a side surface of the suction unit  120 . The sensing range of a physical collision with an obstacle can be increased. 
     Referring back to  FIG.  2   , the side bumper switches  122   b  and  122   c  may protrude further than both the sides of the cleaner body  110  in a side direction. In other words, the width of the cleaner head with bumper switches is wider than the width of the cleaner body. When an obstacle is located on a side surface of the robot cleaner  100 , the side bumper switch  122   b  or  122   c  collides with the obstacle earlier than the cleaner body  110 , so that the obstacle can be effectively sensed. 
     The bumper switch  122  includes a bumper  122 ′ and a switch  122 ″. The bumper  122 ′ is a part mounted to the case  121  to be exposed to the outside and movable inwards, and the bumper  122 ′ is pressurized when it is in contact with an obstacle. 
     An elastic member or elastic spring pressurizes the bumper  122 ′ to the outside. The elastic spring may be provided at the inside of the bumper  122 ′ so that the bumper  122 ′ returns to the original state when the bumper  122 ′ is pressurized by the obstacle. The elastic member may be supported by the bumper  122 ′ and the case  121 . The switch  122 ″ is provided at the inside of the bumper  122 ′ to generate an electrical signal by being pressurized when the bumper  122 ′ is moved inward. A micro-switch may be used as the switch  122 ″. 
     If a contact signal with an obstacle is transmitted through the bumper switch  122 , the controller determines that the suction unit  120  has collided with the obstacle to control the driving of the wheel unit  111 . For example, the controller may apply a driving force in the opposite direction to the main wheels  111   a  such that the robot cleaner  100  moves rearward. Alternatively, the controller may apply a driving force to only any one of the main wheels  111   a  or apply a driving force in different directions to both the main wheels  111   a  such that the robot cleaner  100  rotates. 
     In the above, the bumper switch  122  is configured to be divided into the front bumper switch  122   a  and the side bumper switches  122   b  and  122   c , but the present disclosure is not limited thereto. The bumper switch  122  may be also formed in a ‘⊏’ shape to cover the front and left and right surfaces of the case  121 . In such a case, the bumper switch  122  is configured to be movable to a rear side (when a portion provided at the front surface of the case  121  is in contact with an obstacle), a right side (when a portion provided at the left surface of the case  121  is in contact with an obstacle), and a left side (when a portion provided at the right surface of the case  121  is in contact with an obstacle). 
     As described above, when a mechanical bumper switch  122  is provided in the suction unit  120 , a collision with an obstacle may be directly sensed as compared with when an electronic sensor (e.g., an acceleration sensor, a PSD sensor, etc.) is provided. Further, manufacturing cost can be reduced, and a circuit configuration can be simplified. In addition, an improved function of sensing an obstacle and changing a direction can be implemented by the combination of the bumper switch  122  and the sensing unit  130  provided to the cleaner body  110 . 
     Meanwhile, when the robot cleaner is located close to a step, cliff, or a surface having a steep profile, an additional avoidance operation may be required. If an additional sensing of such a situation and control corresponding to the sensing are not provided, the robot cleaner may break after falling from the step, or may be unable to recover to climb or drive over the steep surface to perform cleaning again. To this end, the cliff sensor  124  that senses topography thereunder is provided at a front end portion of a lower side of the suction unit  120 . 
     The cliff sensor  124  may be provided with a light emitting part (light emitter) and a light receiving part (light receiver), and measures a distance between the cliff sensor  124  and a floor G by measuring a time for which a beam irradiated onto the floor G from the light emitting part is received to the light receiving part. When a rapidly lowered surface exists at the front, the received time increases rapidly. When a cliff or step exists at the front, the emitted beam is not received by the light receiving part. 
     In these figures, it is illustrated that an inclined part  120   a  upwardly inclined with respect to the floor G is formed at the front end portion of the lower side of the suction unit  120 , and the cliff sensor  124  is installed at the inclined part  120   a  to face the floor G. According to the above-described structure, the cliff sensor  124  is provided inclined toward the floor G at a front lower side of the suction unit  120 . Therefore, topography the front lower side of the suction unit  120  may be sensed by the cliff sensor  124 . Alternatively, the cliff sensor  124  may be provided parallel to the floor G to sense topography immediately under the cliff sensor  124 . 
     If it is sensed through the cliff sensor that the topography under the cliff sensor is lowered to a certain level or lower, the controller controls the driving of the wheel unit  111 . For example, the controller may apply a driving force in the opposite direction to the main wheels  111   a  such that the robot cleaner  100  moves rearward in the reverse direction R. Alternatively, the controller may apply a driving force to only any one of the main wheels  111   a  or apply a driving force in different directions to both the main wheels  111   a  such that the robot cleaner  100  rotates. 
     The cliff sensor  124  may also be provided at the bottom surface of the cleaner body  110 . By considering the function of the cliff sensor  124 , a cliff sensor provided to the cleaner body  110  may be provided adjacent to the rear of the cleaner body  110 . 
     For reference, as the inclined part  120   a  is formed at the front end portion of the lower side of the suction unit  120 , the robot cleaner  100  can easily climb a low threshold or obstacle. In addition, as shown in these figures, when an auxiliary wheel  123  is provided at the inclined part  120   a , the climbing may be more easily performed. For reference, the auxiliary wheel  123  is omitted in  FIG.  14    so as to describe the cliff sensor  124 . 
     Because the robot cleaner  100  is autonomously driven, it is required to charge the battery  180  provided in the cleaner body  110  to continuously use the robot cleaner  100 . In order to charge the battery  180 , a charging station as a power supply is provided, and a charging terminal  125  configured to be connectable to the charging station is provided in the suction unit  120 . In these figures, it is illustrated that the charging terminal  125  is provided at the inclined part  120   a  to be exposed to the front. The charging terminal  125  may be provided between the cliff sensors  124  which are provided at both sides of the suction unit  120 . 
     Meanwhile, a brush roller  126  may be provided in the suction unit  120  to permit effective suction of dust. The brush roller  126  is rotatable in the inlet port  120   b ′ to sweep foreign substances, e.g., dust and allow the dust to be introduced into the suction unit  120 . 
     By considering the function of the brush roller  126 , foreign substances may become stuck to the brush roller  126  over a length of time. Although there are needs for cleaning of the brush roller  126 , the suction unit  120  typically has a structure making it difficult to disassemble the suction unit  120 , resulting in difficulty to clean the brush roller  126 . In the present disclosure, the brush roller  126  can be separated and cleaned easily without entire disassembly of the suction unit  120 . 
     Referring to  FIG.  17   , the case  121  includes a main case  121   a  and a cover case  121   b  (or inner case). The main case  121   a  is provided with the rotatable brush roller  126 , and an opening  121   a ′ is formed at one side of the main case  121   a . The front bumper switch  122   a  is mounted at a front side of the main case  121   a , and any one of the side bumper switches  122   b  and  122   c  is mounted at the other side of the main case  121   a . 
     The cover case  121   b  is detachably coupled to the main case  121   a  to open/close the opening  121   a ′ provided at the one side of the main case  121   a . The other of the side bumper switches  122   b  and  122   c  is mounted to the cover case  121   b . If the cover case  121   b  is separated from the main case  121   a , the opening  121   a ′ provided at the one side of the main case  121   a  is exposed to the outside. The brush roller  126  provided in the main case  121   a  may be exposed to the outside through the opening  121   a ′. 
     The manipulation part  127  (lock/unlock switch) through which locking of the cover case part  121   b  to the main case part  121   a  is released in manipulation thereof may be provided in the suction unit  120 . The manipulation part  127  may be implemented in various types such as a slide type and a press type. In this embodiment, the manipulation part  127  of the slide type is installed at the main case part  121   a . An elastic member or elastic spring  128  elastically pressurizes the brush roller  126  inside the other side of the main case  121 . A leaf spring, a coil spring, and the like may be used as the elastic member  128 . 
     When the elastic member  128  is pressurized, the brush roller  126  held by the cover case  121   b  is fastened to the main case  121   a . If the fastening is released by the manipulation of the manipulation part  127 . 
     Referring to  FIG.  18   , air introduced into the suction unit  120  through the inlet port  120   b ′ of the suction unit  120  is introduced into the cleaner body  110  through the communication part  120   b ″. The air introduced into the cleaner body  120  is introduced into the dust container  140 . The intake flow path corresponds to a flow path continued from the introduction port  110 ′ communicating with the communication part  120   b ″ to the first opening  110   a  (see  FIG.  19   ). The intake flow path may be formed as a duct, a peripheral component(s), or a combination of the duct and the peripheral component(s). As illustrated, an intake duct  117  connects the introduction port  110 ′ to the first opening  110   a , thereby forming the inhalation flow path. 
     The communication part  120   b ″ of the suction unit  120  may be provided under a bottom surface of the front side of the cleaner body  110 . In this case, the introduction port  110 ′ is formed in the bottom surface of the front side of the cleaner body  110 . In addition, as the dust container  140  is provided at the rear of the cleaner body  110 , a fan motor module  170  and the battery  180  are provided at both left and right sides of the front of the dust container  140 , respectively. 
     A front end portion of the inlet duct  117  communicating with the introduction port  110 ′ (inlet port) is formed to extend upward. In addition, the inlet duct  117  extends to one side of the cleaner body  110  while avoiding the battery  180 . In this case, the inlet duct  117  may be provided to pass over the fan motor module  170  provided at the one side of the cleaner body  110 . 
     The first opening  110   a  is formed in an upper inner circumferential surface of the dust container accommodation part  113  to communicate with the entrance  140   a  formed in an upper outer circumferential surface of the container  140 . The inlet duct  117  is formed to extend upward toward the first opening  110   a  from the introduction port  110 ′. 
     Air introduced into the dust container  140  passes through at least one cyclone in the dust container  140 . Foreign substances, e.g., dust contained in the air is separated by the at least one cyclone and collected in the dust container  140 . The air having the foreign substances removed therefrom is discharged from the dust container  140 . 
     Air forms a rotational flow in the dust container  140 , and foreign substances and air are separated from each other by a difference in centrifugal force between the air and the dust. The air is flowed into the exit  140  via the at least one cyclone by a suction force generated by the fan motor module  170 . Since an inertial force caused by the weight of the foreign substance is larger than the suction force generated by the fan motor module  170 , the foreign substances are collected at a lower portion of the dust container  140  by gradually falling into the dust container  140 . 
     The introduction port  110 ′ may be formed at the bottom center surface of the front side of the cleaner body  110 . The entrance  140   a  of the dust container  140  may be formed opened in a tangential direction in an inner circumferential surface of the dust container  140  such that air is introduced in a lateral direction to naturally form a rotational flow. In the state in which the dust container  140  is accommodated in the dust container accommodation part  113 , the entrance  140   a  may be located in a lateral direction of the cleaner body  110 . 
     The air having the dust separated therefrom is discharged or exhausted from the dust container  140  and then is finally discharged to the outside through the exhaust port  112  via the exhaust port in the cleaner body  110 . The exhaust flow path corresponds to a flow path from the second opening  110   b  (see  FIG.  19   ) to the exhaust port  112 . The exhaust flow path may be formed as a duct, a peripheral component(s), or a combination of the duct and the peripheral component(s). 
     The exhaust flow path is configured as a combination of an exhaust duct  118  that connects the second opening  110   b  to the fan exhaust port of the fan motor module  170  and an internal component(s) that guides the flow of air from the fan exhaust port  170  to the exhaust port  112 . The fan exhaust port may be provided adjacent to a central portion of the cleaner body  110  to reduce noise discharged to the outside. Correspondingly, the second opening  110   b  may also be formed adjacent to the central portion of the cleaner body  110 . 
     A front end portion of the exhaust duct  118  communicating with the second opening  110   b  and a rear end portion of the intake port  117  communicating with the first opening  110   a  may be provided side by side at the same height. 
     Referring to  FIG.  19   , the dust container accommodation part  113  (dust container dock) to dock the dust container  140  therein is formed in the cleaner body  110 . The dust container accommodation part  113  has a shape indented toward a front side from a rear side of the cleaner body  110 , and is opened rearward and upward. The dust container accommodation part  113  may be defined by a bottom surface supporting the dust container  140  and an inner wall surrounding a portion of the outer circumference of the dust container  140 . 
     A recessed part  116  (recess) dented from the top surface of the cleaner body  110  is formed along the outer circumference of the dust container accommodation part  113 . The dust container cover  150  is provided for in the dust container accommodation part  113  and rotatably hinged. The dust container cover  150  is provided to simultaneously cover the top surface of the dust container  140  and the recessed part  116  (see  FIG.  2   ). A portion of the dust container cover  150  is accommodated in the recessed part  116  in the state in which the dust container cover  150  is coupled to the dust container  140 . 
     The first opening  110   a  and the second opening  110   b  are formed in the inner wall of the dust container accommodation part  113 . The first opening  110   a  and the second opening  110   b  may be provided at the same height. As illustrated, the first opening  110   a  and the second opening  110   b  are laterally formed adjacent to each other at an upper end of the inner wall of the dust container accommodation part  113 . 
     In order to form the flow of air continued from the intake flow path to the exhaust flow path through the dust container  140 , the first and second openings  110   a  and  110   b  are to be provided to respectively communicate with the entrance  140   a  and the exit  140   b . In order to permit the communication, the dust container  140  is to be mounted at a normal position of the dust container accommodation part  113 . 
     A mounting or alignment projection  113   b  is formed to protrude from the bottom surface of the dust container accommodation part  113 , and a mounting or alignment groove  149  (see  FIG.  22   ) corresponding to the mounting projection  113   b  is formed in a bottom surface of the dust container  140 . The dust container  140  may be mounted at the normal position of the dust container accommodation part  113  as the mounting projection  113   b  is accommodated in the mounting groove  149 . 
     The mounting projection  113   b  may be formed at a position such that the dust container  140  shaped cylindrically is not rotated when docked in the dust container accommodation part  113 . For example, the mounting projection  113   b  may be formed at both left and right sides with respect to the center of the dust container  140 . 
     The positions of the mounting projection  113   b  and the mounting groove  149  may be reversed to each other. The mounting projection may be formed to protrude from the bottom surface of the dust container  140 , and the mounting groove may be formed in the bottom surface of the dust container accommodation part  113 . 
     A protruding part or a protrusion  113   a  may be formed to protrude from the bottom surface of the dust container accommodation part  113 , and a groove part or a recess  148  (see  FIG.  22   ) corresponding to the protruding part  113   a  may be formed in the bottom surface of the dust container  140 . The groove part  148  may be formed at the center of the dust container  140 . 
     The dust container accommodation part  113  or the dust container  140  may be provided with gaskets  110   a ′ and  110   b ′ that maintain airtightness between the first opening  110   a  and the entrance  140   a  and airtightness between the second opening  110   b  and the exit  140   b  when the dust container  140  is mounted at the normal position of the dust container accommodation part  113 . The gaskets  110   a ′ and  110   b ′ may be formed to surround the first opening  110   a  and the second opening  110   b , or be formed to surround the entrance  140   a  and the exit  140   b . 
     As illustrated in  FIGS.  20  and  21   , the dust container  140  is accommodated in the dust container accommodation part  113  formed at the other side of the cleaner body  110 , and is configured to collect dust filtered from sucked air. The dust container  140  may be formed in a cylindrical shape, and include an external case  141   a  defining appearance, an upper case  141   b , an upper cover  141   d , and a lower case  141   c . 
     The external case  141   a  is formed in a cylindrical shape with both ends open so as to define a side appearance of the dust container  140 . The dust container  140  is provided with the entrance  140   a  through which unfiltered air is introduced, and the exit  140   b  through which filtered air is discharged. The entrance  140   a  and the exit  140   b  may be formed through a side surface of the external case  141   a . The entrance  140   a  and the exit  140   b  may be arranged at the same height. The entrance  140   a  and the exit  140   b  may be formed adjacent to each other at an upper end of the external case  141   a . 
     At least one cyclone may be provided in the external case  141   a . For example, a first cyclone  147   a  filtering larger substances and/or particles from air introduced through the entrance  140   a  and a second cyclone  147   b  provided in the first cyclone  147   a  to filter fine substance and/or particles may be provided in the external case  141   a . 
     The unfiltered air, introduced into the dust container  140  through the entrance  140   a  flows along the first cyclone  147   a  as an empty space which is formed in an annular shape between the external case  141   a  and the inner case  141   h . During the flow, relatively heavy particles (e.g., debris and/or dust) is dropped down and collected and relatively light air is introduced into the inner case  141   h  through a mesh filter  141   h ′ by a suction force. Finer particles (e.g., fine dust and/or ultrafine dust) may be introduced into the inner case  141   h  together with the air. 
     The mesh filter  141   h ′ is mounted in the inner case  141   h  to spatially partition inside and outside of the inner case  141   h . The mesh filter  141   h ′ is formed in a mesh shape or a porous shape such that the air can flow therethrough. 
     A criterion for distinguishing sizes of dust and fine dust may be decided by the mesh filter  141   h ′. Foreign substances and/or particles as small as passing through the mesh filter  141   h ′ may be classified as the fine dust, and foreign substances and/or particles failing to pass through the mesh filter  141   h ′ may be classified as the dust. 
     Foreign materials and dust which have dropped down without passing through the mesh filter  141   h ′ are collected in a first storage portion or chamber S 1  located under the mesh filter  141   h ′. The first storage portion S 1  is defined by the external case  141 , the inner case  141   h  and the lower case  141   c . 
     A skirt  141   h   1  may be provided at a lower side of the mesh filter  141   h ′ protruding along a circumference of the inner case  141   h . The skirt  141   h   1  may restrict air flow into the first storage portion S 1  located under the skirt  141   h   1 . This may result in preventing the foreign materials and dust collected in the first storage portion S 1  from being dispersed and upward reverse flow toward the skirt  141   h   1 . 
     The second cyclone  147   b  is configured to separate fine dust from the air introduced therein through the mesh filter  141   h ′. The second cyclone  147   b  includes a cylindrical portion and a conical portion extending downwardly from the cylindrical portion. In the cylindrical portion, the air rotates due to a guide vane provided in therein. In the conical portion, the fine dust and the air are separated from each other, and the second cyclone  147   b  may be provided in plurality. The second cyclones  147   b  may be arranged within the first cyclone  147   a  in an up and down direction of the dust container  140 . The height of the dust container  140  may be reduced with respect to the arrangement structure of the second cyclones on the first cyclone. 
     The air introduced into the inner case  141   h  is introduced into intake openings  147   b ′ on upper portions of the second cyclones  147   b . An empty space in which the second cyclones  147   b  are not arranged within the inner case  147   h  is used as a path along which the air flows upward. The empty space may be formed by the adjacent cyclones  147   b  and/or by the inner case  141   h  and the second cyclones  147   b  adjacent to the inner case  141   h . 
     A vortex finder  147   b   1  through which air from which the fine dust is separated is discharged is provided on a center of the upper portion of each second cyclone  147   b . The intake opening  147   b ′ may be defined as an annular space between an inner circumference of the second cyclone  147   b  and an outer circumference of the vortex finder  147   b   1 . 
     A guide vane extending in a spiral shape along an inner circumference is provided in the intake opening  147   b ′ of the second cyclone  147   b . The guide vane allows air introduced in the second cyclone  147   b  through the introduction opening  147   b ′ to be rotated. The vortex finder  147   b   1  and the guide vane are arranged in the cylindrical portion of the second cyclone  147   b . Additional details may be found in U.S. Application Serial No. 15/487,756 (Attorney Docket No. P-1509), and U.S. Application Serial No. 15/487,821 (Attorney Docket No. P-1510), both filed on Apr. 14, 2017, whose entire disclosures are incorporated herein by reference. 
     The fine dust gradually flows downward while spirally orbiting along the inner circumference of the second cyclone  147   b , is discharged through a discharge opening  147   b ″ and is finally collected in a second storage portion S 2 . The air which is relatively lighter than the fine dust is discharged through the upper vortex finder  147   b   1  by a suction force. 
     The second storage portion or chamber S 2  may be called as a fine dust storage portion in the aspect of forming a storage space of the fine dust. The second storage portion S 2  is a space defined by an inside of the inner case  141   h  and the lower case  141   c . 
     A cover  141   k  is arranged on the top of the second cyclones  147   b . The cover  141   k  is provided to cover the intake openings  147   b ′ of the second cyclones  147   b  with a predetermined interval. The cover  141   k  is provided with communication holes  141   k ′ corresponding to the vortex finders  147   b   1 . The cover  141   k  may be provided to cover the inner case  141   h  except for the vortex finders  147   b   1 . 
     A partition plate  141   b   2  is installed on outer circumferences of the second cyclones  147   b . The partition plate  141   b   2  partitions a space such that the air introduced into the inner case  141   h  through the mesh filter  141   h ′ is not mixed with the fine dust discharged through the discharge opening  147   b ″. The air passed through the mesh filter  141   h ′ flows above the partition plate  141   b   2  and the fine dust discharged through the discharge opening  147   b ″ is collected below the partition plate  141   b   2 . 
     The discharge opening  147   b ″ of the second cyclone  147   b  has a shape penetrating through the partition plate  141   b   2 . The partition plate  141   b   2  may be formed integral with the second cyclone  147   b , or may be mounted on the second cyclone  147   b  after being produced as a separate member. 
     A flow separation member or guide  141   g  is provided on an inner upper portion of the external case  141   a . The flow separation member  141   g  separates a flow of air introduced through the entrance  140   a  of the dust container  140  from a flow of air discharged through the exit  140   a  of the dust container  140 . 
     The upper case  141   b  is provided to cover the flow separation member  141   g , and the lower case  141   c  is provided to cover a lower portion of the external case  141   a . The flow separation member  141   g , the upper case  141   b , the upper cover  141   d  and the filter  141   f  will be described later. 
     Since the dust container  140  is configured to be detachably coupled to the dust container accommodation part  113 , a handle  143  may be provided to the dust container  140  such that the dust container  140  may be grabbed for detachment from the dust container accommodation part  113 . The handle  143  is hinge-coupled to the upper case  141   b  to be rotatable. A handle accommodation part or recess  142  having the handle  143  accommodated therein is formed in the upper case  141   b . 
     When the dust container cover  150  is coupled to the dust container  140  to cover the dust container  140 , the handle  143  may be pressurized by the dust container cover  150  to be accommodated in the handle accommodation part  142 . In a state in which the dust container cover  150  is separated from the dust container  140 , the handle  143  may protrude from the handle accommodation part  142 . To this end, the upper case  141   b  may be provided with an elastic part or elastic spring that elastically pressurizes the handle  143 . 
     A locking hook  145  may be formed to protrude from the upper case  141   b . The locking hook  145  is formed at the front of the upper case  141   b . The front of the upper case  141   b  means a direction toward the front of the cleaner body  110  when the dust container  140  is mounted normally in the dust container accommodation part  113 . 
     The locking hook  145  is accommodated in an accommodation or locking groove  116   a  formed in the recessed part  116  of the cleaner body  110 . The locking hook  145  may have a shape protruding from an outer circumferential surface of the upper case  141   b  to be bent downward. A step  116   a ′ is formed in the accommodation groove  116   a , and the locking hook  145  may be configured to be locked to the step  116   a ′. See  FIGS.  35 - 36   . 
       FIG.  22    is a bottom view of the dust container  140  illustrated in  FIG.  20   . The lower case  141   c  may be rotatably coupled to the external case  141   a  by a hinge  141   c ′. A lock  141   c ″ provided to the lower case  141   c  is detachably coupled to the external case  141   a , to allow the lower case  141   c  to be fixed to the external case  141   a  when the lock  141   c ″ is coupled to the external case  141  and to allow the lower case  141   c  to be rotatable with respect to the external case  141   a  when the coupling is released. 
     The lower case  141   c  is coupled to the external case  141   a  to form a bottom surface of the first storage portion S 1  and the second storage portion S 2 . When the lower case  141   c  is rotated by a hinge portion  141   c ′ to simultaneously open the first storage portion S 1  and the second storage portion S 2 , the dust and the fine dust may simultaneously be discharged. 
     The hinge  141   c ′ and the lock  141   c ″ may be provided at positions opposite to each other with the center of the lower case  141   c , which is interposed therebetween. When the dust container  140  is normally mounted in the dust container accommodation part  113 , the hinge part  141   c ′ and the locking member  141   c ″ may be covered by the inner wall of the dust container accommodation part  113  and not exposed to the outside. 
     The mounting groove  149  corresponding to the mounting projection  113   b  is formed at a bottom surface of the lower case  141   c . As shown in  FIG.  21   , the mounting groove  149  may be formed at a position adjacent to the hinge part  141   c ′ and the locking member  141   c ″. The groove part  148  corresponding to the protruding part  113   a  may be formed in the bottom surface of the lower case  141   c . The groove part  148  may be formed at the center of the dust container  140 . 
       FIG.  23    is a view illustrating a state in which the dust container  140  is mounted in the dust container accommodation part  113  shown in  FIG.  19   . When the dust container  140  is not mounted in the dust container accommodation part  113 , the dust container cover  150  may be provided upwardly inclined by a hinge  150   a  that provide an upward elastic force. The dust container  140  may be inserted downwardly inclined at a rear upper side of the dust container accommodation part  113  for docketing in the dust container accommodation part  113 . 
     If the dust container  140  is docked normally, the locking hook formed to protrude from the outer circumference of the dust container  140  is accommodated in the accommodation groove  116   a  formed in the recessed part  116  of the cleaner body  110 . The accommodation groove  116   a  has a shape dented relatively further than the recessed part  116 . 
     Accordingly, the step  116   a ′ is formed in the accommodation groove  116   a . The step  116   a ′ is inserted into the inside of the locking hook  145  to be locked when the locking hook  145  is moved in a lateral direction. In the state in which the dust container cover  150  is coupled to the dust container  140 , the duct container cover  150  is provided to cover the locking hook  145 . When the dust container  140  is accommodated in the dust container accommodation part  113 , a top surface of the upper case  141   b  of the dust container may be at the same plane as the recessed part  116 . 
     An alignment mark  146  may be formed at an upper portion of the dust container  140 , and a guide mark  116 ′ corresponding to the alignment mark  146  may be formed at the recessed part  116 , so that the locking hook  145  can be accommodated at the regular position of the accommodation groove  116   a . The alignment mark  146  may be engraved or painted in the upper case  141   b  and the guide mark  116 ′ may be engraved or painted in the recessed part  116 . 
     The accommodation groove  116   a  may be formed to extend long toward the front of the cleaner body  110 . When the dust container cover  150  is coupled to the dust container  140 , the hinge  150   a  of the duct container cover  150  may be accommodated into the accommodation groove  116   a . 
     The locking hook  145  is locked to the step  116   a ′ of the accommodation groove  116   a , so that the dust container  140  is restricted from being moved in the lateral direction in the dust container accommodation part  113 . The mounting projection  113   b  of the dust container accommodation part  113  is inserted into the mounting groove  149  formed in the dust container  140 . The dust container  140  is also restricted from being moved in the lateral direction in the dust container accommodation part  113 . 
     The dust container  140  may not separate from the dust container accommodation part  113  except when the dust container  140  is moved upward. When the dust container cover  150  is fastened to the dust container  140  to cover the dust container  140 , the dust container  140  is also restricted from being moved upward. Thus, the dust container  140  cannot be separated from the dust container accommodation part  113 . 
     Referring to  FIGS.  24  to  30    in conjunction with  FIG.  20   , the upper cover  141   d  is configured to open/close an upper opening  141   b ′ of the dust container  140 . The upper opening  141   b ′ may be formed in the upper case  141   b , and the upper cover  141   d  is detachably coupled to the upper case  141   b  to open/close the upper opening  141   b ′. The upper opening  141   b ′ is provided to overlap with the cover  141   k . See  FIG.  30   . 
     The upper cover  141   d  is provided with manipulation parts  141   d ′ (lock/unlock mechanical switch) that allows the upper cover  141   d  to be fastened to the upper case  141   b  and allow the fastening to be released. The manipulation parts  141   d ′ may be respectively formed at both left and right sides of the upper cover  141   d , to permit pressing in directions opposite to each other, i.e., inward and returning to the original state by an elastic force. See  FIG.  29   . 
     The upper cover  141   d  is provided with fixing projections  141   d ″ withdrawn or retracted from the outer circumference of the upper cover  141   d  in linkage with the manipulation of the manipulation part  141   d . When the pressing manipulation of the manipulation parts  141   d ′ is performed, the fixing projections  141   d ″ are retracted into accommodation parts formed in the upper cover  141   d  not to protrude from the outer circumference of the upper cover  141   d . If the manipulation parts  141   d ′ are turned to the original state by the elastic force, the fixing projections  141   d ″ protrude from the outer circumference of the upper cover  141   d . 
     A fixing groove  141   b ″ having the fixing projection  141   d ″ inserted and fixed thereinto is formed in an inner surface of the upper case  141   b , which forms the upper opening  141   b ′. The fixing groove  141   b ″ may be formed at a position corresponding to each of the fixing projections  141   d ″, so that the fixing grooves  141   b ″ are opposite to each other. The fixing groove  141   b ″ may be formed in a loop shape to extend along the inner surface of the upper case  141   b  to allow a greater degree of freedom in installing the fixing projections  141   d ″. 
     The flow separation member or guide  141   g  that separate the flow of the air introduced through the entrance  140   a  from the flow of the air discharged toward the exit  140   a , and guides the air flow in the dust container  140 . The flow separation member  141   g  may be coupled to an upper end portion at an inner side of the external case  141   a . 
     First and second holes  141   a ′ and  141   a ″ corresponding to the entrance  140   a  and the exit  140   b  of the dust container  140  are formed through the external case  141   a . A first opening  141   g ′ and a second opening  141   g ″ corresponding to the first and second holes  141   a ′ and  141   a ″ are formed through the flow separation member  141   g . With this structure, when the flow separation member  141   g  is coupled to the inner side of the external case  141   a , the first hole  141   a ′ and the first opening  141   g ′ communicate with each other to form the entrance  140   a  of the dust container  140 , and the second hole  141   a ″ and the second opening  141   g ” communicate with each other to form the exit  140   b  of the dust container  140 . See  FIG.  29   . 
     The flow separation member  141   g  may be provided with insertion protrusions  141   g   2  which are inserted into recesses  141   a   1  formed on an inner circumferential surface of the external case  141   a . A support rib  141   g   3  may protrude from an upper portion of the flow separation member  141   g  along a circumference, such that the flow separation member  141   g  can be supported on an upper end of the external case  141   a . 
     The flow separation member  141   g  has a hollow portion and is provided with a flow separating part  141   g   1  surrounding the hollow portion along a circumference. The hollow portion of the flow separation member  141   g  is configured to overlap the cover  141   k  such that air discharged through the communication holes  141   k ′ can be introduced into an upper portion of the flow separating parts  141   g   1 . 
     The first and second openings  141   g ′ and  141   g ″ are formed on surfaces of the flow separation member  141   g , which are opposite to each other. As shown in this figure, the first opening  141   g ′ is provided on a bottom surface of the flow separation member  141   g , so that air introduced through the entrance  140   a  flows at a lower portion of the flow separation member  141   g . The second opening  141   g ″ is provided on a top surface of the flow separation member  141   g , so that air discharged toward the exit  140   b  flows at an upper portion of the flow separation member  141   g . 
     The flow separation member  141   g  is formed to block between the first opening  141   g ′ and the second opening  141   g ″, so that air introduced through the first opening  141   g ’ and air discharged toward the second opening  141   g ″ are separated from each other. The first opening  141   g ′ may be provided with a guide part  141   g   4  which extends from one side of the first opening  141   g ′ to guide air introduced into the dust container  140  to form a rotational flow. The exit  140   b  of the dust container  140  may be formed to minimize flow loss and to harmonize with peripheral structures without interruption. 
     The first opening  141   g ′ and the second opening  141   g ″ may be laterally provided side by side along the circumference of an upper portion of the flow separation member  141   g . Accordingly, the entrance  140   a  and the exit  140   b  of the dust container  140  corresponding to the first and second openings  141   g ’ and  141   g ″, respectively, may be formed at the same height of the dust container  140 . The entrance  140   a  is formed at an upper portion of the dust container  140  such that air introduced into the dust container  140  does not scatter dust collected on the bottom of the dust container  140 . 
     In a cleaner (e.g., an upright type cleaner, a canister type cleaner, etc.) in which the height of the multi-cyclone is less restricted, an exit is typically installed at a position higher than that of an entrance. However, in the robot cleaner  100  of the present disclosure, when the capacity of the dust container  140  is to increase while considering of height restriction, the exit  140   b  along with the entrance  140   a  may be formed at the same height of the dust container  140 . 
     In the structure of the present disclosure, in which air introduced through the entrance  140   a  is guided by the downwardly inclined flow separating part  141   g   1  (inclined guide), an angle at which the air introduced through the entrance  140   a  flows downward is related to inclination of the flow separating part  141   g   1 . In this respect, if the inclination of the flow separating part  141   g   1  is large, the air introduced through the entrance  140   a  does not receive a sufficient centrifugal force, and may scatter dust collected on the bottom of the dust container  140 . 
     The inclination of the flow separating part  141   g   1  may be relatively as small as possible. Since the flow separating part  141   g   1  is continued from an upper side of the entrance  140   a  to a lower side of the exit  140   b , when the entrance  140   a  and the exit  140   b  are formed at the same height of the dust container  140 , the downward inclination of the flow separating part  141   g   1  becomes more gentle as the length of the flow separating part  141   g   1  becomes longer. The flow separating part  141   g   1  is formed longest when the second opening  141   g ″ is located immediately next to the first opening  141   g ′. 
     As illustrated, the entrance  140   a  and the exit  140   b  are laterally formed side by side at an upper end of the external case  141   a . The flow separation member  141   g  may have a shape downwardly inclined spirally along an inner circumferential surface of the external case  141   a  from an upper end of the first opening  141   g ′ to the lower end of the second opening  141   g ″. 
     The inner case  141   h , the cover  141   k  and the flow separation member  141   g  are coupled together. The inner case  141   h  may be provided with coupling bosses  141   h ” for coupling to the cover  141   k  and the flow separation member  141   g . 
     The multi-cyclone provided within the dust container  140  filters foreign substances or dust in air introduced into the dust container  140  through the entrance  140   a . The air having the foreign substances or dust filtered therefrom ascends and flows toward the exit  140   b  at an upper portion of the flow separating part  141   g   1 . In the present disclosure, the dust container  140  has a structure in which foreign substances or dust is again filtered before the air flowing as described above is finally discharged through the exit  140   b . 
     A filter  141   f  that passes through the multi-cyclone and then filters foreign substances or dust in air discharged toward the exit  140   b  is provided at a rear surface of the upper cover  141   d . The filter  141   f  is provided to cover the cover  141   k , so that dust in air passing through the vortex finder of the second cyclone  147   b  can be filtered by the filter  141   f . 
     When the upper cover  141   d  is mounted to the upper case  141   b , the filter  141   f  is provided to cover the cover  141   k . For example, the filter  141   f  may be adhered closely to the top surface of the flow separating part  141   g   1  or be adhered closely to a top surface of the cover  141   k . 
     The filter  141   f  may be mounted to a mounting rib  141   e  protruding from the rear surface of the upper cover  141   d . The mounting rib  141   e  includes a plurality of protruding parts  141   e ′ and a mounting part  141   e ″. The mounting rib  141   e  may be integrally formed with the upper cover  141   d  in injection molding of the upper cover  141   d . 
     The protruding parts  141   e ′ are formed to protrude from the rear surface of the upper cover  141   d , and are provided at a plurality of places, respectively. The mounting part  141   e ″ is provided to be spaced apart from the rear surface of the upper cover  141   d  at a certain distance, and is supported at a plurality of places by the plurality of protruding parts  141   e ′. The mounting part  141   e ″ may be formed in a loop shape larger than the hollow portion of the flow separation member  141   g . 
     The filter  141   f  includes a filter part  141   f ′ and a sealing part  141   f ′. The filter part  141   f  is provided to cover the hollow portion of the flow separation member  141   g  or the cover  141   k  to filter foreign substances or dust in air discharged through the communication holes  141   k  of the cover  141   k . The filter part  141   f ′ may have a mesh shape. 
     The sealing part  141   f ″ is provided to surround the filter part  141   f , and is mounted to the mounting part  141   e ″ to allow the filter  141   f  to be fixed to the mounting rib  141   e . In order for the filter  141   f  to be fixed to the mounting rib  141   e , a groove into the mounting part  141   e ″ is inserted may be formed in the sealing part  141   f ″. The sealing part  141   f ″ may be adhered closely to the top surface of the flow separating part  141   g   1  or the top surface of the cover  141   k  to cover the communication holes  141   k ′ of the cover  141   k . 
     Air from which foreign substances or dust is filtered by the multi-cyclone is discharged toward the exit  140   b  through an empty space between the protruding parts  141   e ′ by passing through the filter part  141   f . Here, the empty space is formed at the outer circumference of the filter  141   f , and communicates with an upper portion of the flow separating part  141   g   1 . In addition, the sealing part  141   f ″ is configured to seal a gap between the filter  141   f  and the top surface of the flow separating part  141   g   1  adhered closely to the filter  141   f  or the top surface of the cover  141   k , so that it is possible to prevent foreign substances or dust in air from being discharged toward the exit  140   b  through the gap. 
     Referring to  FIGS.  31  and  32    in conjunction with  FIGS.  1  to  3   , the dust container cover  150  is rotatably coupled to the cleaner body  110  by a hinge  150   a , and is provided to completely cover a top surface of the dust container  140  when the dust container cover  150  is coupled to the dust container  140 . In this state, a portion of the dust container cover  150  is accommodated in at the dust container accommodation part  113 , and the other portion of the dust container cover  150  may be formed to protrude toward the rear of the cleaner body  110  (i.e., in the reverse direction R opposite to the forward direction F). The hinge  150   a  is configured to elastically pressurize the dust container cover  150  in the upper direction. When the dust container cover  150  is not coupled to the dust container  140 , the dust container cover  150  may be tilted upwardly inclined with respect to the top surface of the dust container  140 . 
     The dust container cover  150  may be formed in an elliptical shape in the front-rear direction of the cleaner body  110  to completely cover the circular dust container  140  when the dust container cover  150  is coupled to the dust container  140 . A recessed part  116  dented from the top surface of the cleaner body  110  is formed along the outer circumference of the dust container accommodation part  113  in the cleaner body  110  (see  FIGS.  19  and  23   ). The dust container cover  150  is accommodated in the dust container accommodation part  113  through rotation thereof. 
     The dust container cover  150  is provided to simultaneously cover the top surface of the dust container and the recessed part  116 . A front-rear length of the dust container cover  150  corresponding to the front-rear direction of the cleaner body  110  may be formed longer than a left-right length of the dust container cover  150  corresponding to the left-right direction of the cleaner body  110 . The left-right direction is formed equal to or longer than a radius of the dust container cover  150 . 
     The dust container cover  150  may be provided with at least one of a touch key  150 ′, a touch screen  150 ″, and a display. The touch screen  150 ″ may be distinguished from the display that outputs visual information but has no touch function, in that the touch screen  150 ″ outputs visual information and receives a touch input to the visual information. The dust container cover  150  may include a top cover  151 , a bottom cover  152 , and a middle frame  153  between the top cover  151  and the bottom cover  152 . The components may be formed of a synthetic resin material. 
     The top cover  151  may be configured to have a certain degree of transparency. For example, the top cover may be translucenct. Alternatively, the top cover itself may be formed to be transparent, and a film attached to a rear surface of the top cover  151  may be translucenct. As the top cover  151  has the transparency, a pictogram of the touch key  150 ′ or visual information output from the touch screen  150 ″ or the display may be transmitted to a user through the top cover  151 . 
     A touch sensor that senses a touch input to the top cover  151  may be attached to the rear surface of the top cover  151 . The touch sensor may constitute a touch key module  154   a  and/or a touch screen module  154   b , which will be described later. 
     The bottom cover  152  is coupled to the top cover  151 , so that the top cover  151  and the bottom cover  152  form an appearance of the dust container cover  150 . The bottom cover  152  may be formed of an opaque material, and form a mounting surface on which electronic devices or a sub-circuit board  151  can be mounted in the dust container cover  150 . 
     The hinge  150   a  rotatably coupled to the cleaner body  110  may be coupled to the top cover  151  or the bottom cover  152 . The hinge part  150   a  may be provided in the top cover  151  or the bottom cover  152 . 
     The electronic devices or the sub-circuit board  157  may be mounted on the bottom cover  152 . For example, the sub-circuit board  157  electrically connected to a main circuit board of the cleaner body  110  may be mounted on the bottom cover  152 . The main circuit board may be configured as an example of the controller for operating various functions of the robot cleaner  100 . 
     Various electronic devices are mounted on the sub-circuit board  157 . In  FIG.  23   , the touch key module  154   a , the touch screen module  154   b , and infrared receiving units  156  (e.g., IR sensors) are electrically connected on the sub-circuit board  157 . The electrical connection includes not only that the electronic devices are mounted on the sub-circuit board  157  but also that the electronic devices are connected to the sub-circuit board  157  through a flexible printed circuit board (FPCB). 
     A pictogram may be printed on the top cover above the touch key module  154   a , and the touch key module  154   a  is configured to sense a touch input to the pictogram of the top cover  151 . The touch key module  154   a  may include a touch sensor, and the touch sensor may be provided to be attached or adj acent to the rear surface of the top cover  151 . The touch key module  154   a  may further include a backlight unit that lights the pictogram. 
     The touch screen module  154   b  provides an output interface between the robot cleaner  100  and the user through the output of visual information. The touch screen module  154   b  senses a touch input to the top cover  151  to provide an input interface between the robot cleaner  100  and the user. The touch screen module  154   b  includes a display that outputs visual information through the top cover  151  and a touch sensor that senses a touch input to the top cover  151 , and the display and the touch sensor form a mutual-layered structure or is integrally formed, thereby implementing a touch screen. 
     The touch screen module  154   b  may be accommodated in a through-hole  153   b  of the middle frame  153  to be coupled to the middle frame  153  through bonding, hook-coupling, or the like. In this case, the touch screen module  154   b  may be electrically connected to the sub-circuit board  157  through the FPCB. The touch screen module  154   b  may be attached to or provided adjacent to the rear surface of the top cover  151 . 
     The dust container cover  150  may be provided with an acceleration sensor  155 . The acceleration sensor  155  may be mounted on the sub-circuit board  157  or be electrically connected to the sub-circuit board  157  through the FPCB. The acceleration sensor  155  senses a gravitational acceleration acting on the acceleration sensor  155 , which is divided into X, Y, and Z vectors perpendicular to one another. 
     The controller may sense whether the dust container cover  150  has been opened/closed, using X, Y, and Z vector values sensed by the acceleration sensor  155 . Specifically, based on a state in which the dust container cover  150  is closed, at least two vector values are changed in a state in which the dust container cover  150  is opened (tilted). That is, the vector values sensed through the acceleration sensor  155  are changed depending on a degree to which the dust container cover  150  is inclined. 
     When a difference between vector values in the two states is equal to or greater than a preset reference value, the controller may determine that the dust container cover  150  has not been coupled to the dust container  140 , to generate a corresponding control signal. For example, if the dust container cover  150  is in a tilted state as it is opened, the controller  155  may senses the tilted state to stop the driving of wheel unit  111  and generate an alarm. 
     In addition, if vibration is applied to the dust container cover  150 , vector values sensed through the acceleration sensor  155  are changed. When a difference between the vector values, which is equal to or greater than the preset reference value, is sensed within a certain time, the state of the touch screen module  154   b  may be changed from a non-activation (OFF) state to an activation (ON) state. For example, if the user taps the dust container cover  150  plural times in a state in which the touch screen module  154   b  is not activated, the controller may sense the tapping of the user through the acceleration sensor  155  to change the state of the touch screen module  154   b  from the non-activation state to the active state. 
     A gyro sensor may be used instead of the acceleration sensor  155 . The acceleration sensor  155  and the gyro sensor may be used together, so that improved sensing performance can be implemented through complementary detection. 
     The infrared receiving units  156  may be provided at corner portions of the sub-circuit board  157  to receive infrared signals transmitted from directions different from one another. Here, the infrared signal may be a signal output from a remote controller (not shown) for controlling the robot cleaner  100  in manipulation of the remote controller. 
     The middle frame  153  is provided to cover the sub-circuit board  157 , and has through-holes  153   a  and  153   b  respectively corresponding to the touch key module  154   a  and the touch screen module  154   b , which are mounted on the sub-circuit board  157 . Inner surfaces defining the through-holes  153   a  and  153   b  are formed to surround the touch key module  154   a  and a touch screen module  154   b , respectively. 
     An accommodation part  153   c  that is provided to cover an upper portion of each of the infrared receiving units  156  and has an opened front to receive infrared light may be provided at each corner portion of the middle frame  153 . According to the above-described disposal, the infrared receiving unit  156  is provided to face a side surface of the dust container cover  150  (specifically, a side surface of the top cover  151  having transparency). Since the upper portion of the infrared receiving unit  156  is covered by the accommodation part  153   c , it is possible to prevent a malfunction of the infrared receiving unit  156 , caused by a three-wavelength lamp provided on a ceiling or sunlight. 
     At least one portion of the dust container cover  150  may be provided to protrude further than the top surface of the cleaner body  110 . As shown in these figures, the top cover  151  may be provided with a tapered part  151   a  extending downwardly inclined to the outside from a top surface thereof. The tapered part  151   a  may be formed to extend along the outer circumference of the top cover  151 , and be located to protrude further than the top surface of the cleaner body  110  in the state in which the dust container cover  150  is coupled to the dust container  140  as shown in  FIG.  3   . 
     If a side surface vertically downwardly extending from the top surface of the top cover  151  is continuously formed, an infrared signal introduced into the top cover  151  at a corner portion of the top cover  151  is refracted or reflected, and therefore, the receiving performance of the infrared receiving unit  156  may be deteriorated. Further, if the side surface of the top cover  151  is completely covered by the top surface of the cleaner body  110 , the receiving performance of the infrared receiving unit  156  may further deteriorate. 
     An infrared signal introduced into the top cover  151  can be introduced into the infrared receiving unit  156  provided adjacent to the inside of the tapered part  151   a  without being almost refracted or reflected by the tapered part  151   a . In addition, as the tapered part  151   a  is located to protrude further than the top surface of the cleaner body  110 , and the infrared receiving unit  156  is provided in plural numbers to be spaced apart from each other at a certain distance inside the tapered part  151   a , infrared signals can be received in all directions. Thus, the receiving performance of the infrared receiving unit  156  may be improved. 
     Referring to  FIGS.  33  and  34    in conjunction with  FIG.  20   , the dust container cover  150  is provided with the hook  158  configured to be fastened to a locking part  144  of the dust container  140 . In these figures, it is illustrated that the hook part  158  is formed to protrude at one side of the bottom surface of the bottom cover  152 . The hook part  158  may be provided at the opposite side of the hinge  150   a . 
     When the hook  158  is fastened to the locking part  144 , the handle  143  provided at an upper portion of the dust container  140  is pressurized by the dust container cover  150  to be accommodated in the handle accommodation part  142 . If the fastening between the hook part  158  and the locking part  144  is released, the handle  143  is pressurized by the elastic member to protrude from the handle accommodation part  142 . As described above, the handle  143  may be provided inclined with respect to the upper case  141   b . 
     The locking part  144  provided in the dust container  140  includes a button part  144   a  and a holding part  144   b . The locking part  144  is exposed to the rear of the cleaner body  110 . 
     The button part  144   a  is provided at a side surface of the dust container  140  to permit pressing manipulation, and the holding part  146   b  is configured such that the hook part  158  of the dust container cover  150  can be locked thereto. Also, the holding part  146   b  is configured such that the locking of the holding part  146   b  to the hook part  158  is released in the pressing manipulation of the button part  144   a . The holding part  144   b  may be formed at an upper portion of the dust container  140 . 
     In the above, the case where the hook part  158  is provided in the dust container cover  150  and the locking part  144  is provided in the dust container  140  has been described as an example, but formation positions of the hook part  158  and the locking part  144  may be changed from each other. In other words, the locking part may be provided in the dust container cover  150  and the hook part may be provided in the dust container  140 . 
     As described above, the dust container cover  150  is detachably coupled to the dust container by the fastening structure between the hook part  158  and the locking part  144 . That is, there exists no direct fastening relation between the dust container cover  150  and the cleaner body  110 , and the dust container cover  150  is fastened to the dust container  140  accommodated in the dust container accommodation part  113 . 
     As described above, the dust container  140  accommodated in the dust container accommodation part  113  is restricted from being moved in the lateral direction by the fastening between the mounting projection  113   b  and the mounting groove  149  and the fastening between the locking hook  145  and the step  116   a ′. In the state in which the dust container  140  is accommodated in the dust container accommodation part  113 , if the dust container cover  150  is fastened to the dust container  140  in a state in which the dust container cover  150  covers the dust container  140 , the dust container  140  is also restricted from being moved upward. Thus, the dust container  140  can be prevented from being separated from the dust container accommodation part  113 . 
     When the dust container  140  is not mounted, the dust container cover  150  is in a state in which it is freely rotatable about the hinge part  150   a , i.e., a non-fixing state. As described above, the dust container cover  150  may be provided upwardly tilted in the non-fixing state. 
     The dust container cover  150  is provided in a horizontal state when the dust container cover  150  is fastened to the dust container  140 . If the dust container cover  150  is not fastened to the dust container  140 , the dust container cover  150  is in a state in which it is tilted upwardly inclined. When the dust container  140  is not accommodated in the dust container accommodation part  113 , the dust container cover  150  is also in the state in which it is tilted upwardly inclined. Thus, the user can intuitively check whether the dust container cover  150  has been fasted to the dust container  140 , by checking, with the naked eye, whether the dust container cover  150  is in the state in which it is tilted. 
     Air filtered in the dust container  140  is discharged from the dust container and finally discharged to the outside through the exhaust port  112 . A filter unit  160  that filters fine dust included in the filtered air is provided at the front of the exhaust port  112 . 
     Referring to  FIGS.  35  to  37   , the filter unit  160  is accommodated in the cleaner body  110 , and is provided at the front of the exhaust port  112 . The filter unit  160  is exposed to the outside when the dust container  140  is separated from the dust container accommodation part  113 . The exhaust port  112  may be formed in an inner wall of the cleaner body  110  that defines the dust container accommodation part  113 . The exhaust port  112  may be formed at one (left or right) end portion of the cleaner body  110  that surrounds the dust container accommodation part  113 . In this exemplary embodiment, it is illustrated that the exhaust port  112  is formed long along the height direction of the cleaner body  110  at the left end portion of the dust container accommodation part  113  on the drawing. 
     Air discharged from the second opening  110   b  is guided to the exhaust port  112  through the exhaust flow path. In the structure in which the exhaust port  112  is formed at the one end portion of the cleaner body  110 , the exhaust flow path extends to the one end of the cleaner body  100 . The filter unit  160  is provided on the exhaust flow path. 
     The filter unit  160  includes a filter case  161  and a filter  162 . The filter case  161  is provided with a hinge part  161   c  hinge-coupled to the inner wall of the cleaner body  110  that defines the dust container accommodation part  113 . The filter case  161  is configured to be rotatable with respect to the cleaner body  110 . 
     The filter case  161  includes a filter accommodation part  161   a  (filter housing) and a ventilation port  161   b  that communicates with the filter accommodation part  161   a  and is provided to face the exhaust port  112 . Air introduced into the filter case  161  is discharged to the ventilation port  161   b  via the filter  162  mounted in the filter accommodation part  161   a . 
     The filter  162  is mounted in the filter accommodation part  161   a . A HEPA filter for filtering fine dust may be used as the filter  162 . A handle  162   a  may be provided to the filter  162 . 
     In  FIG.  30   , it is illustrated that the filter accommodation part  161   a  is formed at a front surface of the filter case  161 , and the ventilation port  161   b  is formed in a side surface of the filter case  161 . More specifically, a through-hole  161   e  is formed in the side surface of the filter case  161 , and a guide rail  161   f  protrudes along the insertion direction of the filter  162  on a bottom surface of the filter case  161  to guide the insertion of the filter  162  through the through-hole  161   e . 
     The structure in which the filter  162  is mounted in the filter case  161  is not limited thereto. As another example, unlike the structure shown in  FIG.  30   , the filter  162  may be mounted at a front surface of the filter case  161  to be accommodated in the filter accommodation part  161   a . In this case, the filter  162  may be fixed to the filter accommodation part  161   a  through hook coupling. 
     The filter case  161  may be received in the cleaner body  110  through an opening  115  formed in the inner wall of the cleaner body  110 , and an outer surface of the filter case  161  is exposed to the outside in the state in which the filter case  161  is received in the cleaner body  110  to define the dust container accommodation part  113  together with the inner wall of the cleaner body  110 . To this end, the outer surface of the filter case  161  may have a rounded shape, and be preferably formed as a curved surface having the substantially same curvature as the inner wall of the dust container accommodation part  113 . 
     A knob  161   d  may be formed on one surface of the filter case  161  that defines the dust container accommodation part  113  together with the inner wall of the cleaner body  110 . Referring to  FIGS.  2  and  19   , when the dust container  140  is accommodated in the dust container accommodation part  113 , the dust container  140  is configured to cover the filter case  161 , and the knob  161   d  is not exposed to the outside as the dust container  140  covers the knob  161   d . 
     The filter case  161  may be provided in the dust container accommodation part  113  in a state in which the filter case  161  is rotated to open the opening  115 . The filter accommodation part  161   a  is exposed to the outside, so that the filter  162  can be easily replaced. 
     Therefore, an aspect of the detailed description is to provide a new sensing unit capable of minimizing a sensing part, implementing a front monitoring/photographing function, a simultaneously localization and mapping function, and an obstacle sensing function, and improving obstacle sensing performance. 
     Another aspect of the detailed description is to provide a suction unit capable of more directly sensing a collision with an obstacle by complementing the sensing unit, and sensing in advance a step or cliff that is rapidly lowered when the step or cliff exist at the front thereof. 
     Still another aspect of the detailed description is to provide a structure in which a dust container can be firmly fixed to a dust container accommodation part, and assembly convenience of a cleaner body, a dust container, and a dust container cover can be improved. 
     Still another aspect of the detailed description is to provide a new flow structure in a dust container, which can increase the capacity of the dust container while considering a limitation of the height of a cleaner body. 
     Still another aspect of the detailed description is to provide a structure in which a filter for filtering fine dust can be easily replaced. 
     A robot cleaner may include: a cleaner body including a controller, the cleaner body having a dust container accommodation part formed therein; a wheel unit mounted in the cleaner body, the wheel unit of which driving is controlled by the controller; and a dust container detachably coupled to the dust container accommodation part, wherein a first opening and a second opening are provided at the same height in an inner wall of the dust container accommodation part, wherein the dust container includes: an entrance and an exit, provided side by side along the circumference of the dust container, the entrance and the exit, respectively communicating with the first opening and the second opening when the dust container is accommodated in the dust container accommodation part; and a guide part extending downwardly inclined along the inner circumference of the dust container, the guide part separating the flow of air introduced into the entrance from the flow of air discharged toward the exit to be respectively guided to lower and upper portions thereof. 
     The entrance may be provided under the guide part such that the air introduced through the entrance flows at the lower portion of the guide part. The exit may be provided above the guide part such that the air discharged toward the exit flows at the upper portion of the guide part. 
     The guide part may extend from an upper side of the entrance to a lower side of the exit. 
     The exit may be formed immediately next to the entrance. 
     The guide part may be formed to block between the entrance and the exit. 
     At least one cyclone filtering dust in air introduced into the dust container may be provided in the dust container. 
     The cyclone may include: a first cyclone filtering dust from air introduced through the entrance; and a second cyclone accommodated in an accommodation part defined by the guide part, the second cyclone being provided in the first cyclone to filter fine dust. 
     The robot cleaner may further include a filter covering the accommodation part to filter dust in air passing through the second cyclone. 
     The filter may be adhered closely to an inner circumferential surface of the accommodation part. 
     An empty space communicating with the upper portion of the guide part may be formed at the outer circumference of the filter such that air passing through the filter is introduced into the upper portion of the guide part. 
     The dust container may further include: an external case including the entrance, the exit, the accommodation part, and the guide part, the external case accommodating the first and second cyclones therein; an upper case coupled to an upper portion of the external case, the upper case having an upper opening that overlaps with the accommodation part; and an upper cover detachably coupled to the upper case to open/close the upper opening, the upper cover having the filter mounted to a rear surface thereof. 
     A robot cleaner may include: a cleaner body having a dust container accommodation part formed therein; and a dust container detachably coupled to the dust container accommodation part, wherein the dust container includes: an entrance and an exit, formed at the circumference of the dust container, the entrance and the exit, respectively communicating with a first opening and a second opening, which are formed in an inner wall of the dust container accommodation part, when the dust container is accommodated in the dust container accommodation part; and a guide part extending along the inner circumference of the dust container, the guide part separating the flow of air introduced into an entrance from the flow of air discharged toward an exit to be respectively guided to lower and upper portions thereof; a first cyclone filtering dust from air introduced through the entrance; a second cyclone accommodated in an accommodation part defined by the guide part, the second cyclone being provided in the first cyclone to filter fine dust; and a filter covering the accommodation part to filter dust in air passing through the second cyclone. 
     The filter may be adhered closely to a top surface of the guide part, or be adhered closely to an inner circumferential surface of the accommodation part. 
     An empty space communicating with the upper portion of the guide part may be formed at the outer circumference of the filter such that air passing through the filter is introduced into the upper portion of the guide part. 
     The dust container may further include: an external case including the entrance, the exit, the accommodation part, and the guide part, the external case accommodating the first and second cyclones therein; an upper case coupled to an upper portion of the external case, the upper case including an upper opening that overlaps with the accommodation part; and an upper cover detachably coupled to the upper case to open/close the upper opening, the upper cover having the filter mounted to a rear surface thereof. 
     An autonomous cleaner according to the present disclosure may include a cleaner body having a dust container dock formed therein; and a dust container configured to be separated from the dust container dock. The dust container may include an entrance and an exit formed at a circumference of the dust container, the entrance and the exit, respectively communicating with a first opening and a second opening formed at an inner wall of the dust container dock, when the dust container is positioned in the dust container dock; a flow separation guide extending along an inner circumference of the dust container, the flow separation guide separating the flow of air introduced into an entrance from the flow of air discharged toward an exit such that the air introduced into the entrance is guided to a lower portion of the dust container and filtered air is guided upwards toward the exit; a first cyclone filtering dust from air introduced through the entrance; a second cyclone positioned through an opening defined by a guide wall provided with the flow separation guide, the second cyclone being disposed in the first cyclone to filter fine dust; and a filter covering the opening to filter dust in air exiting through the second cyclone. 
     The filter may be fitted to a top surface of the flow separation guide, or may be fitted to an inner circumferential surface of the guide wall. An air flow guide around an outer circumference of the filter may be provided by an upper surface of the flow separation guide such that air passing through the filter flows above the upper surface the flow separation guide. 
     The dust container may further includes a body case including the entrance, the exit, the opening defined by the guide wall, and the flow separation guide, the body case housing the first and second cyclones; an upper case coupled to an upper portion of the body case, the upper case including an upper opening that overlaps with the opening defined by the guide wall; and an upper cover detachably coupled to the upper case to open/close the upper opening, the upper cover having the filter mounted to a rear surface thereof 
     The present disclosure has advantageous effects as follows. 
     First, the first sensing part is provided inclined with respect to one surface of the cleaner body to simultaneously photograph front and upper parts, and the controller divides a photographed image into front and upper images according to objects different from each other. Thus, the first sensing part can be more efficiently used, and the existing sensing parts provided for every object can be integrated as one. 
     Also, the second sensing part of the sensing unit includes the first and second pattern irradiating parts that respectively irradiate beams having first and second patterns toward a front lower side and a front upper side, and the image acquisition part that photographs the beams having the first and second patterns, so that a front geographic feature and an upper obstacle can be sensed together. As a result, the obstacle avoidance performance of the robot cleaner can be improved. 
     In addition, the first sensing part and the second sensing part are integrated to constitute one module called as the sensing unit, so that it is possible to provide a robot cleaner having a new form factor. 
     Second, the bumper switch that mechanically operates is provided in the suction unit provided to protrude from one side of the cleaner body, so that, when the suction unit collides with an obstacle, the collision can be directly sensed. In addition, side bumper switches respectively provided at both sides of the suction unit are provided to protrude in a lateral direction instead of both sides of the cleaner body, so that the collision with an obstacle in the lateral direction can be effectively sensed. 
     If the bumper switches are combined with the sensing unit, more improved obstacle sensing and a direction changing function corresponding thereto can be realized. 
     In addition, the cliff sensor is mounted at the inclined part of the suction unit, so that when a step or cliff that is rapidly lowered exists at the front, a proper avoidance operation can be performed by sensing the step or cliff in advance. 
     Also, the cover case part of the suction unit is configured to open/close the opening of the main case part, so that the brush roller built in the main case part can be withdrawn to the outside. Thus, the brush roller can be more easily cleaned. 
     Third, the dust container is restricted from being moved rearward by the locking structure between the dust container and the dust container accommodation part in a state in which the dust container is mounted in the dust container accommodation part, and is restricted from being moved upward in a state in which the dust container cover is fastened to the dust container. Thus, the dust container can be firmly fixed to the dust container accommodation part, and assembly convenience of the cleaner body, the dust container, and the dust container cover can be improved. 
     In addition, the accommodation part that is provided to cover an upper portion of each of the infrared receiving units and has an opened front to receive infrared light is provided in the middle frame of the dust container cover, so that it is possible to prevent a malfunction of the infrared receiving unit, caused by a three-wavelength lamp provided on a ceiling or sunlight. In addition, the side surface of the dust container cover is provided to protrude further than the top surface of the cleaner body, so that the receiving performance of the infrared receiving unit can be improved. 
     Fourth, the exit of the dust container is formed at the same height as the entrance of the dust container, so that the capacity of the dust container can be increased without increasing the height of the cleaner body. In addition, as the exit of the dust container is formed immediately next to the entrance of the dust container, the downward inclination angle of the guide part that separates the flow of air introduced into the entrance from the flow of air discharged toward the exit to be respectively guided to lower and upper portions thereof is decreased. Thus, air introduced through the entrance can form a sufficient rotational flow, and dust collected on the bottom of the dust container can be prevented from being scattered. 
     Fifth, the filter case is hinge-coupled to the cleaner body to open/close the opening formed in the inner wall of the dust container accommodation part. Thus, the filter case is provided in the dust container accommodation part in a state in which the filter case is rotated to open the opening, and the filter accommodation part is exposed to the outside, so that the filter can be easily replaced. 
     This application relates to U.S. Application Serial No. 15/599,780 (Attorney Docket No. P-1522), U.S. Application Serial No. 15/599,783 (Attorney Docket No. P-1523), U.S. Application Serial No. 15/599,786 (Attorney Docket No. P-1524), U.S. Application Serial No. 15/599,800 (Attorney Docket No. P-1525), U.S. Application Serial No. 15/599,804 (Attorney Docket No. P-1526), U.S. Application Serial No. 15/599,829 (Attorney Docket No. P-1527), U.S. Application Serial No. 15/599,862 (Attorney Docket No. P-1528), U.S. Application Serial No. 15/599,863 (Attorney Docket No. P-1529) and U.S. Application Serial No. 15/599,894 (Attorney Docket No. P-1531), all filed on May 19, 2017, which are hereby incorporated by reference in their entirety. Further, one of ordinary skill in the art will recognize that features disclosed in these above-noted applications may be combined in any combination with features disclosed herein. 
     Any reference in this specification to “one embodiment,” “an embodiment,” “example embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments. 
     Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.