Obstacle sensor and robot cleaner having the same |
|||||||
申请号 | EP12185970.6 | 申请日 | 2012-09-25 | 公开(公告)号 | EP2575000A2 | 公开(公告)日 | 2013-04-03 |
申请人 | Samsung Electronics Co., Ltd; | 发明人 | Jeong, Yeon Kyu; Kim, Shin; Kim, Jeong Hun; Kim, Jong Owan; Yoon, Sang Sik; Lee, Dong Hun; So, Jea Yun; | ||||
摘要 | An obstacle sensor includes a line light irradiating unit including a light-emitting unit, a light-emitting driving unit to drive the light-emitting unit, and a first conical mirror, an apex of which is disposed towards the light-emitting unit in a light irradiation direction of the light-emitting unit and which converts light emitted from the light-emitting unit into line light irradiated in all directions, and a reflected light receiving unit including a second conical mirror to condense light, that is irradiated from the first conical mirror and is then reflected from an obstacle, a lens, that is spaced from the apex of the second conical mirror by a predetermined distance and transmits the reflected light, an imaging unit to image the reflected light that passes through the lens, an image processing unit, and an obstacle sensing control unit. | ||||||
权利要求 | |||||||
说明书全文 | The present invention relates to an obstacle sensor capable of sensing obstacles in all directions and a robot cleaner including the same. In general, an obstacle sensor irradiates light, ultrasonic waves and the like, senses light or ultrasonic waves reflected from obstacles, judges presence of obstacles and the distance thereof based on time difference, phase difference and intensity difference of the sensed signals or judges the distance using a reflected angle. Recently, a method for measuring the distance between a sensor and an obstacle using point light source or structural light such as line light has been developed. However, use of a point light source causes a problem in that only an obstacle present in the direction of a beam radiated from the point light source is detected. When a point light source sensor is rotated in order to solve this problem, a separate servomechanism and some degree of scanning time are required, thus disadvantageously causing deterioration in efficiency. In a case of using a line light, obstacles present throughout a plurality of regions, not in one point, can be simultaneously detected, but there are problems such as limited detection range and difficultly of formation of uniform line light when a line light is formed using a cylindrical lens of the related art. Therefore, it is an aspect of the present disclosure to provide an obstacle sensor capable of sensing obstacles in all directions by forming uniform line light using a conical mirror and a robot cleaner including the same. Additional aspects and/or advantages will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the disclosure. In accordance with one aspect of the present disclosure, provided is an obstacle sensor including: a line light irradiating unit including: a light-emitting unit; and a first conical mirror, an apex of which is disposed towards the light-emitting unit in a light irradiation direction of the light-emitting unit and which converts light emitted from the light-emitting unit into line light irradiated in all directions; and a reflected light receiving unit including: a second conical mirror to condense light, that is irradiated from the first conical mirror and is then reflected from an obstacle; a lens, that is spaced from the apex of the second conical mirror by a predetermined distance and transmits the reflected light; and an imaging unit to image the reflected light that passes through the lens. The line light irradiating unit may further include: a slit or an axicon lens disposed between the light-emitting unit and the first conical mirror to form light irradiated from the light-emitting unit in the form of a ring. The line light irradiating unit may further include: a slit having at least one groove disposed between the light-emitting unit and the first conical mirror. The slit may have a groove having a ring, cross (+), circular or linear (-) shape. The first conical mirror may be formed by joining two or more conical fragments having different bottom diameters. The obstacle sensor may further include: a rotator to rotate the first conical mirror. An angle of two sides formed on the apex on the vertical cross-section of the first conical mirror may be about 88 degrees to about 90 degrees. The lens of the reflected light receiving unit may be spaced from the apex of the second conical mirror by a focal distance of the lens. The surface of lens or the second conical mirror of the reflected light receiving unit may be coated with a band pass filter to transmit only wavelength of the reflected light. The apex of the first conical mirror of the line light irradiating unit and the apex of the second conical mirror of the reflected light receiving unit may be disposed in opposite directions. The apex of the first conical mirror of the line light irradiating unit and the apex of the second conical mirror of the reflected light receiving unit may be disposed in one direction. The apex of the first conical mirror of the line light irradiating unit and the apex of the second conical mirror of the reflected light receiving unit may face each other. The obstacle sensor may further include: a structure having a hole smaller than an irradiation cross-section area of light irradiated from the light-emitting unit, wherein the hole is disposed between the light-emitting unit and the first conical mirror in a light irradiation path of the light-emitting unit. The line light irradiating unit or the light-emitting unit may be inclined at a predetermined angle from a perpendicular line that is vertical to the ground. The obstacle sensor may further include: an obstacle sensing control unit to analyze an image recorded on the imaging unit and thereby extract the distance or shape of the obstacle. The line light irradiating unit may be provided in plural at different heights from the ground and the obstacle sensing control unit may analyze an image recorded on the imaging unit and thereby determine a height of the obstacle. The lens of the reflected light receiving unit may be a wide-angle lens. In accordance with another aspect of the present disclosure, provided is a robot cleaner including an obstacle sensor to sense obstacles and a driving control unit to control driving based on the sensing results of the obstacle sensor, wherein the obstacle sensor includes: a line light irradiating unit including: a light-emitting unit; a light-emitting driving unit to drive the light-emitting unit; and a first conical mirror, an apex of which is disposed towards the light-emitting unit in a light irradiation direction of the light-emitting unit and which converts light emitted from the light-emitting unit into line light irradiated in all directions; and a reflected light receiving unit including: a second conical mirror to condense light, that is irradiated from the first conical mirror and is then reflected from an obstacle; a lens, that is spaced from the apex of the second conical mirror by a predetermined distance and transmits the reflected light; an imaging unit to image the reflected light that passes through the lens; and an image processing unit to process the image obtained in the imaging unit; and an obstacle sensing control unit to analyze the image recorded in the imaging unit and thereby extract the distance or shape of the obstacle. The apex of the first conical mirror of the line light irradiating unit and the apex of the second conical mirror of the reflected light receiving unit may be disposed in the opposite directions. The line light irradiating unit may be mounted on the bottom of the front surface of the robot cleaner and the reflected light receiving unit may be mounted on the top of the front surface of the robot cleaner. The driving control unit may receive a shape or distance of the obstacle from the obstacle sensor and determine a travel path based on the shape or distance of the obstacle. The line light irradiating unit may be provided in plural at different heights from the ground and the obstacle sensing control unit may analyze an image recorded on the imaging unit and thereby determine a height of the obstacle. The obstacle sensing control unit may transmit a control signal to the light-emitting driving unit to turn the light-emitting unit off when the obstacle sensing control unit determines that the robot cleaner is lift from the ground. The obstacle sensing control unit may transmit a control signal to the light-emitting driving unit to turn the light-emitting unit off when the obstacle sensing control unit determines that a sensor window of the robot cleaner is detached. The robot cleaner may further include: a switch or a photo-interrupter adjacent to the sensor window, wherein the obstacle sensing control unit analyzes a signal output from the switch or the photo interrupter and thereby determines detachment of the sensor window. The obstacle sensing control unit may turn the light-emitting unit on, when the robot cleaner begins to travel, and may turn the light-emitting unit off, when the robot cleaner finishes travel. These and/or other aspects of the disclosure will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
Reference will now be made in detail to the embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. Hereinafter, embodiments of the present disclosure will be described with reference to the annexed drawings in detail. Referring to The light-emitting unit 112 is a light source that emits and irradiates light and may be a laser diode (LD), LED or the like. The type of light-emitting unit 112 is not limited, but a laser diode will be described for convenience of illustration in the following embodiments. The wavelength and amount of light emitted from the laser diode 112 are controlled by the light-emitting driving unit and the wavelength of laser may be an infrared ray region that is invisible to the naked eye or a visible light region. The region of used wavelength is not limited. The light-emitting driving unit 113 drives the light-emitting unit 112 according to the control signal of the obstacle sensing control unit 130 and feeds back the intensity of irradiated light to an obstacle sensing control unit 130 using a photo-detector or the like. The first conical mirror 111 enables light irradiated from the light-emitting unit 112 to be reflected from the surface of the first conical mirror 111 to produce line light that emits at 360 degrees in all directions. The second conical mirror 121 condenses light, that is reflected from the first conical mirror 111, collides with the obstacle and returns back, to the lens 122 and the lens 122 disposed in front of the apex of the second conical mirror 121 forms an image produced by the reflected light on the imaging unit 123. The imaging unit 123 converts an image produced by the light, that is reflected from an imaged target, passes through the lens 122 and contacts the imaging unit 123, into the intensity of an electric signal depending on the intensity of light, transforms the same into a digital signal and records the same. In the embodiment of the present disclosure, a charge-coupled device (CCD) image sensor, a complementary meta-oxide-semiconductor (CMOS) image sensor or the like may be used, although a CMOS image sensor is used in the following embodiments. The light, that is irradiated from the line light irradiating unit 110 and reflected from the obstacle, passes through the second conical mirror 121 and the lens 122 and forms an image on the CMOS image sensor 123, and the digital signal converted via the CMOS image sensor 123 is subjected to image processing via the image processing unit 124 and is then transmitted to the obstacle sensing control unit 130. The line light irradiating unit 110 and the reflected light receiving unit 120 constitute an optical module of the obstacle sensor 100. The obstacle sensing control unit 130 analyzes the image-processed image and extracts the distance between the obstacle sensor and the obstacle, and the shape or position of the obstacle. Also, the obstacle sensing control unit 130 modulates frequency, duty ratio and intensity based on the intensity of feedback laser, transmits a control signal to the light-emitting driving unit and thereby enables a user to irradiate a laser having a desired intensity. The obstacle sensing control unit 130 is not necessarily one module in which the line light irradiating unit 110 is physically joined to the reflected light receiving unit 120 and other apparatus to which the obstacle sensor 100 is mounted, for example, a control unit such as a central processing unit (CPU) or microcontroller (MCU) provided on a movable robot, robot cleaner or the like may be used as the obstacle sensing control unit 130. The configuration of the obstacle sensing control unit 130 is not limited so long as the obstacle sensing control unit 130 is capable of controlling the line light irradiating unit 110 and analyzing information obtained from the reflected light receiving unit 120. Hereinafter, the operation of the obstacle sensor according to one embodiment of the present disclosure will be described with reference to As shown in First, the configuration and operation of the line light irradiating unit 110 will be described. The first conical mirror 111 is disposed in an irradiation direction of the laser diode 112. When the apex of the first conical mirror 111 is directed toward the laser diode 112, the laser irradiated from the laser diode 112 collides with and is reflected from the surface of the first conical mirror 111 to produce line light that is irradiated at 360 degrees in all directions. At this time, a collimator lens (not shown) is disposed between the laser diode 112 and the first conical mirror 111 and can convert laser irradiated from the laser diode 112 into point light. The laser diode 112 provided with a collimator lens may be used or a laser may be directly reflected from the surface of the conical mirror without using a collimator lens. Next, a configuration of the reflected light receiving unit 120 will be described. The second conical mirror 121 is disposed such that the apex thereof is toward the bottom and the lens 122 is disposed under the apex of the second conical mirror 121 and the CMOS image sensor 123 is disposed under the lens 122. When the laser, that is irradiated from the line light irradiating unit 110 and is reflected from the obstacle, collides with the surface of the second conical mirror 121, is condensed on the lens 122 and passes through the lens 122, forms an image on the CMOS image sensor 123, the CMOS image sensor 123 converts the laser into a digital signal and records the same. At this time, a band pass filter to transmit only wavelength of the irradiated laser may be coated on the surface of the lens 122 or the surface of the second conical mirror 121 to remove other signals. Preferably, the lens 112 is disposed on the apex of the second conical mirror 121 so that an image can be accurately formed on the CMOS image sensor 123. However, when such a disposition is physically difficult, the lens 122 may be spaced from the apex of the second conical mirror 121 by a focal distance of the lens 122. The lens 122 means an optical lens and the kind thereof is not limited. When a wide-angle lens having a shorter focal distance than a general lens is used, the distance between the second conical mirror 121 and the lens 122 is shortened and the size of an obstacle sensor can thus be reduced. For example, the focal distance of the wide-angle lens may be 50mm or below. Referring to As shown in Meanwhile, when a plurality of grooves having ring shapes with different sizes are formed in the slit 114, line light can be irradiated to a plurality of different heights. As shown in Although formation of uniform line light may be advantageous in sensing obstacles, the intensity of light may often be changed depending on the direction. In this case, as shown in As shown in The shapes of laser beams shown in Referring to The base of the small hole described in In the obstacle sensor according to one embodiment of the present disclosure, an obstacle sense range is determined by an angle (hereinafter, referred to as an angle of apex) formed by two sides in the vertical cross-section between the first conical mirror 111 and the second conical mirror 121. The elevation angle of line light is determined according to the apex angle of the first conical mirror 111 and an obstacle sense range in up and down directions can be seen. When the apex angle of the first conical mirror 111 is set at 90 degrees, the line light is irradiated in parallel to the ground from the obstacle sensor and an obstacle disposed at the same level as the first conical mirror 111 can be seen. When line light is irradiated upward as in a case in which the obstacle sensor is mounted on the robot cleaner, it may contact the naked eye of the user. At this time, as shown in The apex angle of the second conical mirror 121 determines the position of the closest obstacle the sensor can sense, that is, a minimum distance to an obstacle that can be sensed (hereinafter, referred to as a "minimum sense distance"). As an apex angle of the second conical mirror 121 increases, minimum sense distance decreases, and as an apex angle is decreased, minimum sense distance is increased. When the obstacle sensor according to one embodiment of the present disclosure is disposed as shown in When the values of variables are substituted in Equation 1 and calculated, assuming that the apex angle (ρ) of the second conical mirror 121 is 150 degrees and the distance (b) between the light source and the second conical mirror 121 is 50 mm, the minimum sense angle is 30 degrees in the present embodiment of In this equation, d_min is about 30 mm, since θ_lower is 30 degrees and b is 50 mm. That is, the obstacle disposed at the closest distance that can be sensed by the obstacle sensor shown in The obstacle sensor according to one embodiment of the present disclosure measures the distance to the obstacle using an image recorded in the image sensor 123 and a resolution is changed depending on the measured distance. Also, the maximum sense distance is changed according to FOV of the camera module and the minimum sense distance is changed depending on the apex angle of the second conical mirror 121. As can be seen from As described above, since the sense range of the obstacle is determined by the apex angle of the first and second conical mirrors and FOV of the camera module, the obstacle sensor according to one embodiment of the present disclosure can be used for the desired application by suitably controlling these values. As described above, an elevation or irradiation angle of line light is changed according to the apex angle of the first conical mirror 111, but the apex angle of the first conical mirror 111 is determined during production of the first conical mirror. Control of elevation angle using the apex angle of the first conical mirror 111 may cause limitations on time and costs. Hereinafter, an embodiment in which an elevation angle at which the line light is irradiated can be changed without changing the apex angle of the first conical mirror 111 will be described. When the line light irradiating unit 110 illustrated in the left of Alternatively, as illustrated in the right of By controlling the angle at which the line light irradiating unit 110 or the light-emitting unit 112 is inclined, an obstacle having the desired height can be sensed. Referring to The first conical mirror 111 shown in The rotator 117 is controlled by the obstacle sensing control unit 130 and a control signal transmitted from the obstacle sensing control unit 130 to the rotator 117 may be synchronized with the reflected light receiving unit 120. Referring to As shown in Although a case in which the obstacle is higher than the first line light irradiating unit 110a is illustrated in In order to determine the line light irradiating unit that emits the light received by the reflected light receiving unit 120, light irradiation times of respective line light irradiating units may be different. When the line light irradiating units simultaneously emit light, color of light emitted from respective line light irradiating units may be different. In the embodiment of Alternatively, as illustrated in Accordingly, although a plurality of line light irradiating units do not have different vertical positions, that is, line light irradiating units are not mounted to different heights, obstacles present at different heights can be sensed by controlling the apex angle of the first conical mirror, or inclining the line light irradiating unit or light-emitting unit. Image information may be represented on a two-dimensional image plane. Referring to Calculation of the actual distance between the obstacle sensor and the obstacle will be described in accordance with First, when the laser reflected by the first conical mirror 111 collides with an obstacle and is then returned back, an angle (θi) formed by incident light and reflected light will be described in brief in accordance with the following [Equation 3]. Also, the distance (di) between the obstacle sensor and the obstacle can be obtained using θi and the following [Equation 4]. The obstacle sensor according to the present embodiment may be provided in a variety of apparatuses that require sensing of the obstacle and measurement of the distance between the sensor and the obstacle, in particular, in a movable robot that can autonomously walk or travel. At this time, the optical module of the obstacle sensor may be mounted into the shape shown in In accordance with the obstacle sensor according to one embodiment of the present disclosure, the line light irradiating unit and the reflected light receiving unit are not arranged in a row in a vertical line to realize reduction of the size of the optical module or the efficiency of obstacle sensing, but may be independently arranged at different positions. A detailed description thereof will be described below. Also, the obstacle sensor according to one embodiment of the present disclosure is mounted on the robot cleaner that performs cleaning while autonomously traveling to enable the robot cleaner to run without colliding with the obstacle. Hereinafter, a robot cleaner including an obstacle sensor according to one embodiment of the present disclosure will be described with reference to the drawings. Referring to As described in As shown in Referring to Also, the driving unit 300 drives the robot cleaner 400 according to the driving signal. Also, the slit disposed between the laser diode 112 and the first conical mirror 111 includes a plurality of ring-shaped grooves or a plurality of line light irradiating units 110, as shown in Also, the driving control unit 200 sets a travel path, based on information associated with environments such as distance to and shape of obstacles transmitted from the obstacle sensing control unit 130 and controls the travelling or cleaning operation of the robot cleaner 400 according to the set travel path. Also, the obstacle sensing control unit 130 judges the state of the robot cleaner based on the information obtained from the reflected light receiving unit 120 and turns on/off the obstacle sensor according to the condition of the robot cleaner. Specifically, the obstacle sensing control unit 130 analyzes the information obtained from the reflected light receiving unit 120, that is, the image information associated with the environments of the robot cleaner, and thereby judges detachment of the robot cleaner from the sensor window. The robot cleaner is provided with a sensor window to prevent direct emission of light produced in the light-emitting unit and light emitted from the line light irradiating unit 110 is emitted outside via the sensor window. In another embodiment in which detachment of the sensor window 410 is confirmed, when the sensor window 410 is mounted on the robot cleaner, a sensor window sensing unit such as switch or photo interrupter is mounted in a region which the robot cleaner contacts or is adjacent to the sensor window 410 and the obstacle sensing control unit 130 analyzes a signal output from the sensor window sensing unit and thereby confirms detachment of the sensor window. Referring to For example, whether the robot cleaner is lifted from the ground can be determined by obtaining upper part image information of the robot cleaner obtained from the vision sensor and analyzing the obtained image information. Specifically, when the distance to the ceiling obtained by setting based on the distance between the robot cleaner laid on the ground and the ceiling and calculating image information obtained from the vision sensor is lower than a predetermined level, the robot cleaner is considered to be lifted from the ground. Alternatively, variation in the distance to the ceiling can be sensed by mounting an ultrasonic sensor or the like to sense objects present in the ceiling direction on the top of the robot cleaner, or longitudinal acceleration can be sensed by mounting a longitudinal acceleration sensor, thereby judging the state in which the robot cleaner is lifted from the ground. Alternatively, by analyzing image information obtained from the reflected light receiving unit 120, the state in which the robot cleaner is lifted from the ground can be judged. Also, the obstacle sensing control unit 130 transmits a control signal to the light-emitting driving unit 113 after the robot cleaner begins to travel and thereby turns the light-emitting unit 112 on and the obstacle sensing control unit 130 turns the light-emitting unit 112 off after the robot cleaner finishes travel, thereby reducing power consumption and preventing unnecessary emission of the light source. Also, by disposing the first conical mirror 111 such that the first conical mirror 111 is spaced from the ground by a predetermined distance or more, the running robot cleaner 400 can be controlled to ignore an obstacle having a height that the travelling robot cleaner 400 can pass under. In one embodiment, when the position of the first conical mirror 111 is controlled so that the laser reflected from the first conical mirror 111 is irradiated to a height of 20 mm from the ground, the robot cleaner 400 passes over an obstacle having a height less than 20 mm without sensing the obstacle. However, As described above, the positions of the line light irradiating unit 110 and the reflected light receiving unit 120 are not limited. As shown in When the obstacle sensor is mounted on the robot cleaner 400, it is important to minimize the size of the obstacle sensor. Accordingly, in another embodiment of the present disclosure, as shown in the right of Also, as shown in As described above, in accordance with the obstacle sensor according to one embodiment of the present disclosure, the obstacle sensor uniformly generates line light, thereby sensing obstacles present in all directions, reducing an obstacle sensing dead section according to an elevation angle and extracting the shape of an obstacle. Also, the robot cleaner 400 including the obstacle sensor according to the present disclosure senses obstacles present in all directions and uses the obstacle sensor for driving control, thereby realizing more efficient cleaning and running. When the obstacle sensor according to embodiments of the present disclosure is used, it is possible to form uniform line light, improve accuracy of obstacle sensing, sense obstacles present in all directions using the line light, eliminate the necessity of mounting a plurality of sensors or separate servomechanisms and thus improve economical and structure efficiency. Also, the robot cleaner including the obstacle sensor is capable of accurately sensing obstacles present in all directions, thereby efficiently travelling. Also, the robot cleaner including the obstacle sensor is capable of efficiently controlling the obstacle sensor according to the state of the robot cleaner. Although a few embodiments of the present disclosure have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles of the invention, the scope of which is defined in the claims. |