KR20100098999A - Robot cleaner and method for detecting position thereof - Google Patents

Abstract

PURPOSE: A robot cleaner and a position detecting method there are provided to detect the absolute position of a robot cleaner according to the slick condition of a floor using sensors in all directions. CONSTITUTION: A robot cleaner comprises an absolute position detecting part(100), a relative position detecting part(200), and a control part(300). The absolute position detecting part detects absolute position by extracting a feature point from the upward video information in a regular interval. The relative position detecting part comprises a downward sensor. The downward sensor takes a downward image for a specific time cycle and detects the downward video information. The control part revises the absolute position based on a relative position and produces an environmental map according to the revised absolute position.

Description

ROBOT CLEANER AND METHOD FOR DETECTING POSITION THEREOF}

The present invention relates to a robot cleaner capable of detecting the absolute position of the robot cleaner robustly to the sliding condition of the floor, and a method for detecting the position thereof.

In general, robots have been developed for industrial use and have been a part of factory automation. Recently, the application of robots has been further expanded, medical robots, aerospace robots, and the like have been developed, and home robots that can be used in general homes have also been made.

A representative example of the home robot is a robot cleaner, which is a kind of home appliance that cleans by suctioning dust or foreign matter while driving around a certain area by itself. Such a robot cleaner generally includes a rechargeable battery, and includes an obstacle sensor that can avoid obstacles while driving, so that the robot cleaner can run and clean itself.

In order to clean all the areas while the robot cleaner runs by itself, the robot cleaner should be able to determine the cleaning area such as the cleaned area and the area to be cleaned, and have a function of identifying the magnetic location to identify the cleaning area. .

The robot cleaner according to the related art detects a position through sensors capable of estimating a change in relative motion of a robot such as an encoder connected to a driving motor, a gyroscope, a gyro sensor, and an angular velocity sensor. However, the robot cleaner according to the related art has a problem in that a large position error occurs due to slipping under similar conditions such as a floor on which slipping occurs badly.

SUMMARY OF THE INVENTION An object of the present invention is to provide a robot cleaner and a method for detecting a position thereof, including an upper camera and a lower image sensor, capable of detecting the absolute position of the robot cleaner robustly to the sliding condition of the floor.

Robot cleaner according to an embodiment of the present invention for achieving the above object, the absolute position detection unit for detecting the absolute position by extracting the feature point from the upper image information at a predetermined time period, and the down image information by shooting down at a predetermined time period And a lower position sensor for detecting a position, a relative position detecting unit detecting a relative position according to movement from the lower image information, and correcting the absolute position based on the relative position, and adjusting an environment map according to the corrected absolute position. It is configured to include a control unit for generating.

In addition, the position detection method of the robot cleaner according to an embodiment of the present invention for achieving the above object, the absolute position detection step of detecting the absolute position by extracting the feature point from the upper image information at a predetermined time period, and downward at a predetermined time period A relative position detection step of detecting a relative position according to a movement from down image information by photographing the position, a position correction step of correcting the absolute position based on the relative position, and generating an environment map according to the corrected absolute position It includes a map generation step.

According to the present invention, by including a unit for detecting an absolute position including an upper camera and a unit for detecting a relative position including a lower image sensor, it is possible to reduce the position error due to slippage and to accurately detect the position of the robot cleaner. .

In addition, the cleaning area can be cleaned without omission according to the present invention, thereby improving user convenience and improving system stability.

Hereinafter, a robot cleaner and a position detection method thereof according to the present invention will be described in detail with reference to the accompanying drawings.

1 and 6 together, the robot cleaner according to an embodiment of the present invention, the absolute position detection unit 100 for detecting the absolute position by extracting the feature point from the upper image information at a predetermined time period, and at a predetermined time period A relative position detection unit 200 which detects a relative position according to movement from the downward image information by photographing downward, and corrects the absolute position based on the relative position, and generates an environment map according to the corrected absolute position It comprises a unit 300. In addition, the robot cleaner includes a power unit 400 having a rechargeable battery-type power supply means, a traveling unit 500 including a plurality of wheels to move the robot cleaner, dust and dust on the periphery and the bottom surface during the movement. A cleaning unit 600 for sucking foreign substances, an input unit 700 capable of data input with one or more buttons, an output unit 800 for displaying information on a current operating state and a setting mode, and the environment It further comprises a storage unit 900 for storing the map and the driving route.

The power supply unit 400 supplies the operation power according to the movement of the robot cleaner and cleaning, and when the remaining battery capacity is insufficient, the power supply unit receives the charging current from the charging stand and charges it. The driving unit 500 includes the plurality of wheels and a predetermined wheel motor for rotating the wheels, and the control unit 300 drives the wheel motor to move the robot cleaner. The cleaning unit 600 includes a predetermined suction motor for sucking air, and means for agglomerating dust, and sucks dust or foreign matter from the surroundings. In addition, the robot cleaner according to the present invention may further include an obstacle detecting unit (not shown) that includes a plurality of sensors to detect an obstacle in the vicinity.

Here, the absolute position detection unit 100 includes a top camera 110 for acquiring the upper image information by photographing the upper direction at a predetermined time period, and a feature point extraction unit 120 for extracting feature points from the upper image information. It is configured by. The predetermined time period may be set in advance by a user or the like.

The upper camera 110 uses a lens having a wide angle of view so that all areas of the upper part, for example, all areas of the ceiling can be photographed even at a predetermined position. For example, it includes a lens having an angle of view of 160 degrees or more. The feature point extracting unit 120 may extract the feature point from an arbitrary mark, and in particular, extracts the feature point using a natural mark such as a fluorescent lamp or an interior structure existing in an upper region including the ceiling surface.

A feature point extraction process according to the present invention will be described with reference to FIG. 7. Although the feature point may be extracted after photographing the upper side once, an operation of extracting the feature point by photographing twice during the movement will be described. As shown in FIG. 7, when comparing the first mark C1 and the second mark N1, the robot cleaner moves and the first time k and the second time k + through the upper camera 110. Shoot 1) above, including the ceiling surface. In this case, the first mark C1 and the second mark N1 in the upper image information captured at the first time k and the second time k + 1 are the first feature point M1 and the second feature point ( M2). At this time, the first mark C1 and the second mark N1 are represented by the first feature points M1 (k) and the second feature points M2 (k). On the other hand, the first mark C1 and the second mark N1 at the second time k + 1 are the first feature points M1 (k + 1) and the second feature points M2 (k + 1). appear.

The feature point extracting unit 120 includes a first feature point M1 (k) and a second feature point M2 (k), which are feature points of upper image information on the first mark C1 and the second mark N1, The first feature point M1 (k + 1) and the second feature point M2 (k + 1) are matched and compared to calculate the moving distance between the feature points. That is, as shown in (c) of FIG. 7, the moving distance PL1 and the first distance of the first feature point are compared by comparing the feature points of the image information photographed at the first time k and the second time k + 1. 2 Calculate the movement distance PL2 of the feature point. At this time, the moving distance L1 between the first mark C1 and the second mark N1 and the robot cleaner according to the movement of the robot cleaner is constant and is equal to the actual moving distance of the robot cleaner. However, PL1 and PL2, which are moving distances of the feature points of the captured image information, are different from each other. The farther the mark is, the smaller the movement distance of the feature point relative to the mark, while the closer the mark is to the robot cleaner, that is, the lower the ceiling surface, the larger the difference in the movement distance of the feature point. Accordingly, the feature point extraction unit 120 determines that unnecessary feature points are removed when the movement ratio of the feature points according to the movement of the robot cleaner, such as the second mark N1, is greater than or equal to a predetermined ratio.

Meanwhile, the moving distances are changed when the robot cleaner slides. That is, an error occurs in the absolute position detection using the upper camera 110 according to the relative position variation of the robot cleaner.

In addition, since the first mark C1 of the first point C1 and the second mark N1 is located on the ceiling, the feature point extraction unit 120 uses the distance from the robot cleaner to the ceiling. The height of (N1) is calculated, and if the calculated height is less than or equal to the reference height, it is determined as unnecessary feature point and removed. When the first feature point M1 and the second feature point M2 are compared, the movement distance PL1 of the first feature point M1 and the movement distance PL2 of the second feature point M2 are the first marks, 2 marks, and is proportional to the ratio of the actual travel distance and height of the robot cleaner. In this case, since the actual moving distance is the same and the height of the first feature point M1 is the ceiling height, the height of the second feature point M2, that is, the second mark N1, can be calculated. Here, it is determined that the feature point located at the center of the captured upper image information is located at the ceiling surface, and the height of the feature point is calculated based on the feature point located at the center.

The control unit 300 prepares an environment map based on the absolute position detected through the absolute position detection unit 100. In this case, the control unit 300 may include the feature extraction unit 120 or the feature extraction algorithm, and simultaneously perform location detection and environment map generation using SLAM (Simultaneous Localizaion and Mapping). Can be.

On the other hand, the relative position detection unit 200 includes a downward sensor for detecting downward image information. The lower sensor may use a camera having the same function as the upper camera 110, but unlike the upper camera 110, the lower sensor acquires lower image information by photographing the lower side, that is, the bottom, and thus, the image having different specifications. Use the sensor to acquire. As the downward sensor, an optical flow sensor (OFS) for acquiring the downward image information using light may be used. Here, the optical flow sensor OFS includes an image sensor 210 for capturing the downward image to obtain the downward image information, and at least one light source 220 for adjusting the amount of light.

The operation of the relative position detection unit 200 will be described using the optical flow sensor as an example. The optical flow sensor is provided on the back of the robot cleaner, and photographs the lower side of the robot cleaner, that is, the floor. The optical flow sensor converts the downward image input from the image sensor 210 to generate downward image information of a predetermined format. In this case, the optical flow sensor further includes a lens (not shown) and a lens control unit (not shown) for adjusting the lens, and it is appropriate to use a pan focus lens having a short focal length and a deep depth as the lens. And, the lens control unit is provided with a predetermined motor and moving means to move back and forth to adjust the lens. In addition, the one or more light sources 220 are installed adjacent to the image sensor 210 and irradiate light to an area of the bottom surface photographed by the image sensor 210. That is, when the robot cleaner moves a flat floor, the image sensor 210 is maintained at a constant distance to the floor surface, whereas when the robot cleaner moves the floor surface of the non-uniform surface, the robot cleaner is moved by a predetermined distance or more due to the irregularities and obstacles of the floor. Away. In this case, the one or more light sources 220 adjust the amount of light to be irradiated. On the other hand, the optical flow sensor can detect the relative position regardless of slip. That is, by observing the lower side of the robot cleaner using the optical flow sensor, position correction that is robust against slipping is possible.

The control unit 300 generates an environment map using feature points extracted from the upper image information through the absolute position detection unit 100, and the slip detected from the lower image information through the relative position detection unit 200. The absolute position is fused to correct the absolute position, and the environment map is generated again.

On the contrary, for example, in the case of an optical flow sensor that is not a laser type, a signal may be disconnected when the bottom is a reflective material. At this time, when the image information of the absolute position detection unit 100 is used, it is possible to clearly know whether the signal is cut off due to slip, or cut off because the bottom is a reflective material.

1, 2 and 6 together, the robot cleaner according to another embodiment of the present invention, the absolute position detection unit 100 for detecting the absolute position by extracting the feature point from the upper image information at a predetermined time period, and A relative position detection unit 200 which detects the relative position according to the movement from the downward image information by photographing the downward direction at a predetermined time period, and corrects the absolute position based on the relative position, and generates an environment map according to the corrected absolute position. It is configured to include a control unit 300, the relative position detection unit 200 obtains the downward image information based on the down sensor for detecting the relative position and the wheel motor for driving the wheel of the robot cleaner It is connected to include an encoder (Encoder, 230) for detecting the straight speed and rotation speed. Here, the relative position detection unit 200 may calculate and detect another relative position using the straight speed and the rotation speed of the motor.

On the other hand, the relative position detection unit 200 further includes a gyro sensor (Gyro Sensor, 240) for detecting the rotational speed of the robot cleaner. Here, the relative position detection unit 200 detects another relative position by using the direction information calculated from the rotational speed, and corrects the relative position detected by the downward sensor using this.

Portions described in the robot cleaner according to an embodiment of the present invention are replaced with the following, and will be omitted below.

The robot cleaner may be equipped with the upper camera 110 to acquire a feature point and draw an environment map through image processing, and detect the absolute position of the robot cleaner based on the environment map, but the relative position through the sensors of the robot cleaner. Inaccurate detection results in inaccurate environmental maps, resulting in greater absolute position detection errors. As the sensors, the encoder 230, the gyro sensor 240, or the acceleration sensor is used. The sensors are also used in fusion. In addition, the downward sensor is further added to reduce the error caused by the sliding of the bottom surface generated in these speed sensors. That is, the relative position detection unit 200 easily detects the relative position from the speed by using the encoder 230, the gyro sensor 240, or the encoder and the gyro sensor, The relative position is corrected by using the downward sensor, which is robust against slip caused by materials and the like. Therefore, the control unit 300 corrects the absolute position detected by the absolute position detection unit 100 using the corrected relative position, and generates an environment map.

Referring to FIG. 3, a method of detecting a position of a robot cleaner according to an embodiment of the present disclosure includes an absolute position detection step (S100) of extracting a feature point from upper image information at a predetermined time period and detecting an absolute position at a predetermined time period. Relative position detection step (S200) of detecting the relative position according to the movement from the down image information by shooting down, position correction step (S300) for correcting the absolute position based on the relative position, and the corrected absolute position According to the map generation step (S400) for generating an environment map is configured. The predetermined time period may be set by the user or the like. Hereinafter, the configuration of the apparatus will be referred to the configuration of FIGS. 1 and 2.

Referring to FIG. 4, the absolute position detecting step (S100) includes an upward photographing process (S110) of photographing the upper part at a predetermined time period, and an upper information obtaining process (S120) of obtaining the upper image information from the photographed image. And a feature point extraction process (S130) for extracting feature points from the upper image information, and detects an absolute position based on the feature points (S140). The absolute position detecting step S100 may further include a feature point correction process (not shown) for removing unnecessary feature points from the feature points.

A feature point extraction process according to the present invention will be described with reference to FIG. 7. Although the feature point may be extracted after photographing the upper side once, an operation of extracting the feature point by photographing twice during the movement will be described. As shown in FIG. 7, when comparing the first mark C1 and the second mark N1, the robot cleaner includes the ceiling surface at the first time k and the second time k + 1 while moving. Each picture is photographed upward (S110). In this case, the first mark C1 and the second mark N1 in the upper image information photographed at the first time k and the second time k + 1 have the first feature point M1 and the second feature point ( M2). At this time, the first mark C1 and the second mark N1 are represented by the first feature points M1 (k) and the second feature points M2 (k). On the other hand, the first mark C1 and the second mark N1 at the second time k + 1 are the first feature points M1 (k + 1) and the second feature points M2 (k + 1). Appear (S120).

Subsequently, the absolute position detecting step S100 may include a first feature point M1 (k) and a second feature point M2 (k), which are feature points of upward image information of the first mark C1 and the second mark N1. ) And the first feature point M1 (k + 1) and the second feature point M2 (k + 1) are matched and compared to calculate the moving distance between the feature points. That is, as shown in (c) of FIG. 7, the moving distance PL1 and the first distance of the first feature point are compared by comparing the feature points of the image information photographed at the first time k and the second time k + 1. 2 Calculate the movement distance PL2 of the feature point. At this time, the moving distance L1 between the first mark C1 and the second mark N1 and the robot cleaner according to the movement of the robot cleaner is constant and is equal to the actual moving distance of the robot cleaner. However, PL1 and PL2, which are moving distances of the feature points of the captured image information, are different from each other. The farther the mark is, the smaller the movement distance of the feature point relative to the mark, while the closer the mark is to the robot cleaner, that is, the lower the ceiling surface, the larger the difference in the movement distance of the feature point. Accordingly, in the absolute position detecting step S100, when the moving ratio of the feature point according to the movement of the robot cleaner, such as the second mark N1, is greater than or equal to the predetermined ratio, it is determined that the feature point is unnecessary and removed (S130).

Meanwhile, the moving distances are changed when the robot cleaner slides. That is, an error occurs in the absolute position detection according to the relative position variation of the robot cleaner.

Also, in the absolute position detecting step S100, since the first mark C1 of the first mark C1 and the second mark N1 is located on the ceiling surface, the second position is determined by using a distance from the robot cleaner to the ceiling surface. The height of the mark N1 is calculated, and when the calculated height is less than or equal to the reference height, it is determined as an unnecessary feature point and removed. When the first feature point M1 and the second feature point M2 are compared, the movement distance PL1 of the first feature point M1 and the movement distance PL2 of the second feature point M2 are the first marks, 2 marks, and is proportional to the ratio of the actual travel distance and height of the robot cleaner. In this case, since the actual moving distance is the same and the height of the first feature point M1 is the ceiling height, the height of the second feature point M2, that is, the second mark N1, can be calculated. Here, it is determined that the feature point located at the center of the captured upper image information is located at the ceiling surface, and the height of the feature point is calculated based on the feature point located at the center.

The map generation step S400 prepares an environment map based on the absolute position detected in the absolute position detection step S100. In this case, the map generation step S400 may include the feature point extraction algorithm, and simultaneously perform location detection and environment map generation using Simulaneous Localizaion and Mapping (SLAM).

On the other hand, referring to Figure 4, the relative position detection step (S200) is a downward photographing process (S210) for photographing the down at a predetermined time period and the down information acquisition process for obtaining the down image information from the photographed image (S220) ), And detects a relative position according to the movement from the down image information (S230).

In addition, the down information acquisition process (S220), the process of determining whether an error occurs in the photographed image, and as a result of the determination, the process of adjusting the amount of light irradiated downward when the error occurs, and It may consist of a process of re-photographing the down.

The relative position detection step S200 will be described by taking the case of employing the optical flow sensor as an example. The optical flow sensor is provided on the rear surface of the robot cleaner and photographs the bottom of the robot cleaner, that is, the floor (S210). The relative position detection step (S200) converts an inputted downward image to generate downward image information of a predetermined format (S220). The relative position is detected based on the downward image information (S230).

The map generation step S400 generates an environment map using feature points extracted from upper image information. At this time, the position correction step (S300) corrects the absolute position by fusing the relative position that is robust to the slip detected from the down image information, and the map generation step (S400) generates the environment map again.

On the contrary, for example, in the case of a non-laser type optical flow sensor, a signal is interrupted when the bottom is a reflective material. At this time, if the image information in the absolute position detection step (S100) is used, it is clear whether the signal is cut off due to slip or whether the bottom is cut off because it is a reflective material.

3 and 5 together, the position detection method of the robot cleaner according to another embodiment of the present invention, the absolute position detection step (S100) for detecting the absolute position by extracting the feature point from the upper image information at a predetermined time period; A relative position detection step (S200) of detecting a relative position according to a movement from down image information by photographing downwards at a predetermined time period, and a position correction step (S300) of correcting the absolute position based on the relative position; It comprises a map generation step (S400) for generating an environment map according to the corrected absolute position. Hereinafter, the structure of the apparatus will be described with reference to FIGS. 1 and 2, and the parts described in the position detecting method according to the above embodiment will be omitted and replaced.

In this case, the relative position detection step (S200) is a down shooting process (S210) for shooting down at a predetermined time period, and down information acquisition process (S220) for obtaining the down image information from the captured image, and the down image A first detection process (S230) for detecting a first relative position according to movement from the information, a speed detection process (S240) for detecting a speed of a wheel motor driving the wheel of the robot cleaner, and position information calculated from the speed A second detection process (S250) for detecting a second relative position using the step and correcting the first relative position based on the second relative position (S280 to S281) is configured. Correcting the first relative position based on the second relative position includes comparing the first relative position with the second relative position to determine whether the first relative position is within a preset error range (S280), and the determination result error. If out of the range, the first relative position is corrected based on the second relative position. Here, the error range is set in advance by the user or the like. Of course, the second relative position may be corrected based on the first relative position (S281). After the correction, the relative position is finally detected (S290).

That is, the position detection method detects a straight speed or a rotation speed of the wheel motor driving the wheel of the robot cleaner (S240), and detects a second relative position by double integration of the straight speed or the rotation speed (S250). . Meanwhile, the position detecting method photographs the bottom of the robot cleaner, that is, the bottom (S210), obtains down image information from the photographed down image (S220), and determines a first relative position based on the down image information. It is detected (S230). Wherein the second relative position can be easily detected from the configuration of the robot cleaner, the position error occurs due to the sliding according to the characteristics of the floor material. On the other hand, the first relative position can detect the relative position robustly to the slip. Then, the first relative position and the second relative position is compared (S280). It is determined whether the difference between the two relative positions is within the error range (S280), the relative position is corrected according to the determination result (S281), and finally the relative position is detected (S290).

On the other hand, the relative position detection step (S200) is a downward photographing process (S210) for photographing the down at a predetermined time period, the down information acquisition process (S220) for obtaining the down image information from the photographed image and the down image A first detection process (S230) for detecting a first relative position according to movement from the information, a rotation speed detection process (S260) for detecting a rotation speed of the robot cleaner, and a direction information calculated from the rotation speed; And a third detection step (S270) of detecting the third relative position, and a step (S280 to S281) of correcting the first relative position based on the third relative position. Compensating the first relative position based on the third relative position includes comparing the first relative position with the third relative position to determine whether the first relative position is within a preset error range (S280), and the determination result error. If out of the range, the first relative position is corrected based on the third relative position (S281). Here, the error range is set in advance by the user or the like. Of course, the third relative position may be corrected based on the first relative position. Finally, the relative position is detected after the correction (S290).

That is, the rotation speed, that is, the angular velocity of the robot cleaner, is detected using a gyro sensor for detecting the direction of the robot cleaner (S260), and the third relative position is detected by double integration of the angular velocity (S270). Meanwhile, the robot cleaner is photographed downward, that is, the floor (S210), and the down image information is obtained from the photographed down image (S220), and a first relative position is detected based on the down image information (S230). Wherein the third relative position can be easily detected from the configuration of the robot cleaner, the position error occurs due to the sliding according to the characteristics of the floor material. On the other hand, the first relative position can detect the relative position robustly to the slip. Then, the first relative position and the third relative position is compared (S280). It is determined whether the difference between the two relative positions is within the error range (S280), the relative position is corrected according to the determination result (S281), and the final relative position is detected (S290).

In addition, the relative position detection step (S200) is according to the second relative position according to the straight or rotational speed of the wheel motor, the rotational speed of the robot cleaner, that is, the third relative position according to the angular speed, and the down image information By comparing the first relative position at once (S280), it is possible to determine the relative position according to the comparison result (S290).

Accordingly, the map generation step S400 generates an environment map using the feature points extracted from the upper image information. At this time, the position correction step (S300) corrects the absolute position by fusing the relative position that is robust to the slip detected from the down image information, and the map generation step (S400) generates the environment map again.

On the contrary, in the case of an optical flow sensor that is not a laser type, a signal is broken when the bottom is a reflective material. At this time, if the image information in the absolute position detection step (S100) is used, it is clear whether the signal is cut off due to slip or whether the bottom is cut off because it is a reflective material.

As described above, the robot cleaner and the method for detecting its position according to the present invention include a unit for detecting an absolute position including an upper camera and a unit for detecting a relative position including a lower image sensor to reduce a position error due to slipping. It is possible to reduce and precisely detect the position of the robot cleaner, thereby cleaning the cleaning area without omission. In addition, according to the present invention, it is resistant to changes in the floor environment, and can reduce the position recognition error even in a dark environment in which the upper camera cannot operate.

1 is a block diagram schematically showing the configuration of a robot cleaner according to an embodiment of the present invention;

2 is a block diagram schematically showing the configuration of a relative position detection unit of a robot cleaner according to another embodiment of the present invention;

3 is a flow chart schematically showing a method for detecting a position of a robot cleaner according to an embodiment of the present invention;

4 is a flowchart illustrating an example for describing the position detection method of FIG. 3;

5 is a flow chart schematically showing a relative position detection method of the position detection method of the robot cleaner according to another embodiment of the present invention;

6 is a perspective view showing the appearance of the robot cleaner according to the present invention;

7 is a conceptual view illustrating an absolute position detection method of the robot cleaner according to the present invention.

Claims (13)

An absolute position detection unit for detecting an absolute position by extracting feature points from the upper image information at a predetermined time period; A relative position detection unit having a downward sensor for detecting downward image information by shooting downward at a predetermined time period, and detecting a relative position according to movement from the downward image information; And And a control unit for correcting the absolute position based on the relative position and generating an environment map according to the corrected absolute position. The method of claim 1, wherein the absolute position detection unit, An upper camera photographing the upper part at a predetermined time period to obtain the upper image information; And And a feature point extraction unit for extracting feature points from the upper image information. The method of claim 1, wherein the downward sensor, And an optical flow sensor for obtaining the downward image information by using light. The method of claim 3, wherein the optical flow sensor, An image sensor for capturing the downward image to obtain the downward image information; And And at least one light source for adjusting the amount of light. The method of claim 1, wherein the relative position detection unit, And an encoder connected to a wheel motor for driving wheels of the robot cleaner to detect a speed. And correcting the relative position using the position information calculated from the speed. The method of claim 1, wherein the relative position detection unit, And a gyro sensor for detecting a rotation speed of the robot cleaner. Robot cleaner, characterized in that for correcting the relative position using the direction information calculated from the rotation speed. An absolute position detection step of detecting an absolute position by extracting feature points from upper image information at a predetermined time period; Relative position detection step of detecting the relative position according to the movement from the down image information by photographing the down at a predetermined time period; A position correction step of correcting the absolute position based on the relative position; And And a map generation step of generating an environment map according to the corrected absolute position. The method of claim 7, wherein the absolute position detection step, An upper photographing process of photographing the upper part at a predetermined time period; An upward information acquisition process of obtaining the upward image information from the captured image; And And a feature point extraction process for extracting feature points from the upper image information. The method of claim 8, wherein the absolute position detection step, And a feature point correction process for removing unnecessary feature points from the feature points. The method of claim 7, wherein the relative position detection step, Down shooting process to shoot down at a certain time period; And And a downward information acquisition process of acquiring the downward image information from the photographed image. And detecting the relative position according to the movement from the downward image information. The method of claim 10, wherein the downward information acquisition process comprises: Determining whether an error occurs in the captured image; Adjusting the amount of light irradiated downward when the error occurs as a result of the determination; And Re-shooting the downward; Position detection method of the robot cleaner comprising a. The method of claim 7, wherein the relative position detection step, Down shooting process to shoot down at a certain time period; A downward information acquisition process of obtaining the downward image information from the captured image; A first detection step of detecting a first relative position according to a movement from the down image information; A speed detection process of detecting a speed of the wheel motor driving the wheel of the robot cleaner; A second detection step of detecting a second relative position using the position information calculated from the speed; And Correcting the first relative position based on the second relative position. The method of claim 7, wherein the relative position detection step, Down shooting process to shoot down at a certain time period; A downward information acquisition process of obtaining the downward image information from the captured image; A first detection step of detecting a first relative position according to a movement from the down image information; A rotation speed detection process of detecting a rotation speed of the robot cleaner; A third detection step of detecting a third relative position by using the direction information calculated from the rotation speed; And And correcting a first relative position based on the third relative position.

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