Patent Publication Number: US-2010118371-A1

Title: Three-dimensional space scanner

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority of Korean Patent Application No. 10-2008-0111890, filed on Nov. 11, 2008, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a three-dimensional space scanner, and more particularly, to a three-dimensional space scanner which can obtain spatial data by scanning a space around a mobile object not only in the horizontal direction but also in the vertical direction using a mirror that is driven to rotate as well as to tilt. 
     2. Description of the Related Art 
     An autonomous mobile (walking) device such as a mobile robot senses a surrounding object and measures a distance from the object using a laser beam, supersonic waves or the like in order to locate its position and determine a moving direction. 
     Laser range finding is known as a most accurate method for measuring the distance to an object, particularly, by sensing a laser beam reflecting from the object and measuring the time taken for the laser beam to travel to the object and back. 
     A conventional autonomous mobile device adopting such a laser range finding technique scans a surrounding space using laser beams emitted directly along a two-dimensional horizontal plane. Accordingly, the autonomous mobile device can sense surrounding objects and measure distances from the objects only if the objects are located at a specific height corresponding to a laser emitter. 
     That is, sensible objects are limited to those onto which the laser beams are emitted and to those which are located at the same horizontal plane of the laser emitter. Thus, it is impossible to scan other ranges and distance information on only a specific horizontal plane can be obtained. 
     However, while consumer demands on autonomous mobile devices capable of performing more accurate drive and more various operations are increasing, the distance information only on a specific horizontal plane cannot sufficiently ensure safety and functionality. 
     SUMMARY OF THE INVENTION 
     The present invention has been made to solve the foregoing problems with the prior art, and embodiments of the present invention provide a three-dimensional space scanner which can obtain spatial data by scanning a space around a mobile object not only in the horizontal direction but also in the vertical direction using a mirror that is driven to rotate as well as to tilt. 
     According to an aspect of the present invention, the three-dimensional space scanner may include a rotary drive unit transmitting a rotating force from a rotary motor through a vertical rotary shaft; a mirror holder having a plurality of holder guides extending downwards from an underside thereof, wherein the mirror holder is rotated by the rotating force of the rotary drive unit; a mirror provided to tilt inside the mirror holder and rotating together with the mirror holder; a tilt drive unit coupling with the holder guide to rotate and vertically reciprocate below the mirror holder so as to tilt the mirror connected via a rod; and a vertical drive unit vertically reciprocating the tilt drive unit. 
     In an exemplary embodiment, the rod may be hinged to one end of the mirror, which tilts depending a distance of vertical displacement of the tilt drive unit. 
     A range of tilting of the mirror is determined depending on a range of vertical displacement of the rod. 
     The tilt drive unit may vertically reciprocate along an outer circumference of the rotary motor to a lower end of the mirror holder, with a vertical displacement of the tilt drive unit substantially corresponding to a length of the holder guide. 
     The tilt drive unit may include a first plate defining therein a penetrating opening and connected to the vertical drive unit to vertically reciprocate; a second plate defining a central hole in a central portion thereof, which allows the rotary motor to pass through, wherein the second plate is fitted into the opening of the first plate and is rotatably coupled with the first plate; and the rod hinged at one end to the second plate and at the other end to the mirror. 
     The second plate and the rod may rotate inside the opening of the first plate and vertically reciprocate together with the first plate. 
     The second plate may define a plurality of penetrating guide holes in positions corresponding to the holder guides, such that the holder guides are fitted into and coupled with the guide holes. 
     The tilt drive unit may further include a guide rod guiding the tilt drive unit to vertically reciprocate along a predetermined path. 
     The first plate may have a penetrating guide hole in a position corresponding to the guide rod, the guide hole receiving the guide rod. 
     According to embodiments of the invention, the three-dimensional space scanner can obtain spatial data by scanning a space around a mobile object not only in the horizontal direction but also in the vertical direction using the mirror that is driven to rotate as well as to tilt. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective view illustrating a three-dimensional space scanner according to an exemplary embodiment of the invention; 
         FIG. 2  is an exploded perspective view of the three-dimensional space scanner shown in  FIG. 1 ; 
         FIG. 3  is an assembled sectional view illustrating a rotary drive unit and a mirror holder of the three-dimensional spacer shown in  FIG. 2 ; 
         FIGS. 4A to 4D  are enlarged perspective views illustrating a tilt drive unit of the three-dimensional space scanner shown in  FIG. 2 ; 
         FIGS. 5A and 5B  are schematic views illustrating a process of tilting a mirror of the three-dimensional scanner shown in  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
     A three-dimensional space scanner of the present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which an exemplary embodiment thereof is shown. 
       FIG. 1  is a perspective view illustrating a three-dimensional space scanner according to an exemplary embodiment of the invention,  FIG. 2  is an exploded perspective view of the three-dimensional space scanner shown in  FIG. 1 , and  FIG. 3  is an assembled sectional view illustrating a rotary drive unit and a mirror holder of the three-dimensional spacer shown in  FIG. 2 . 
     As shown in  FIGS. 1 and 2 , the three-dimensional scanner of the invention includes a rotary drive unit  100 , a mirror holder  200 , a mirror M, a tilt drive unit  300  and a vertical drive unit  400 . 
     In the autonomous mobile space scanner of the invention, the rotary drive unit  100  is to generate a rotating force for continuously rotating the mirror M for 360 degrees. The rotary drive unit  100  is provided in the lower portion with a rotary motor  110  that rotates a vertical rotary shaft  120 . The rotary motor  110  can be housed inside a case for the purpose of protection. 
     The vertical rotary shaft  120  is coupled at one end with the rotary motor  110  and at the other end with the mirror holder  200  to transmit the rotating force from the rotary motor  110  to the mirror holder  200 . 
     In the meantime, the mirror holder  200  is a rotary member that is axially connected to the vertical rotary shaft  120  to be rotated in a predetermined direction by the rotating force of the rotary drive unit  100 . 
     As shown in the figures, the mirror holder  200  has an angled U-shaped overall configuration with a horizontal portion  210  and sidewalls  230  extending directly vertically from opposite (right and left) ends of the horizontal portion  210 . Substantially the central portion of the horizontal portion  210  is axially connected to the vertical rotary shaft  120 . 
     In addition, a plurality of holder guides  220  extend downwards from the underside of the mirror holder  200 . 
     As shown in  FIG. 3 , the holder guides  220  have a length l to be shorter than the length L of the rotary drive unit (the entire length including the height of the rotary motor and the length of the vertical rotary shaft) in order to prevent an interference between the holder guides  220  and a frame  10  when the mirror holder  200  is rotating. The interference between the holder guides  220  and a frame  10  would otherwise interfere with the rotation of the mirror holder  200 . 
     The holder guides  220  are connected with the tilt drive unit  300  (which will be described later) to rotate the tilt drive unit  300  following the rotation of the mirror holder  200 . The holder guides  220  also act as reference coordinates that guide the vertical displacement of the tilt drive unit  300  as well as controlling the range of the vertical displacement. 
     As a result, the distance of vertical displacement of the tilt drive unit  300  can be acquired through the holder guides  220 , and the range of displacement of the tilt drive unit  300  can also be controlled by adjusting the length of the holder guides  220 . 
     On top of that mirror holder  200 , the mirror M is provided so as to tilt on a horizontal rotary shaft  231  connecting the right and left sidewalls  230 . 
     Specifically, since the mirror M is hinged along the horizontal rotary shaft  231  that connects one with the other of the sidewalls  230  of the mirror holder  200  while extending across the mirror holder  200 , the mirror M can be tilted at a variety of angles without being fixed at a predetermined angle. 
     The mirror M functions not only to reflect a laser beam emitted from a laser emitter (not shown) to an area around the three-dimensional space scanner but also to receive the laser beam reflecting from an obstacle and the like and reflect the beam again to an optical sensor (not shown). 
     Thus, the mirror M can rotate together with the mirror holder  200  at a predetermined rate to scan the laser beam at 360 degrees continuously across the areas around the scanner. 
     In addition, since the mirror M is tilted in a variety of ranges of angle without being fixed to an inclination 45° to scan a surrounding space, it is possible to obtain spatial data including two-dimensional data on a horizontal plane according to a specific height of the related art as well as a vertical distance. 
     In the meantime, the tilt drive unit  300  acts to rotate and vertically reciprocate below the mirror holder  200 , in cooperation with the holder guides  220 . Thereby, the tilt drive unit  300  tilts the mirror M connected thereto using a rod  340 . 
     Below, a detailed description will be given of the construction and operation of the tilt drive unit  300  with reference to  FIG. 4 . 
       FIGS. 4A to 4D  are enlarged perspective views illustrating the tilt drive unit of the three-dimensional space scanner shown in  FIG. 2 . 
     As shown in  FIGS. 2 and 4A , the tilt drive unit  300  includes a first plate  310 , a second plate  320  and the rod  340 . 
     The first plate  310  is connected to the vertical drive unit  400  via a coupling protrusion  314  in the outer circumference thereof and is thus supported by the vertical drive unit  400 . The first plate  310  vertically reciprocates using a rotating force generated by the vertical drive unit  400 . 
     While this embodiment of the invention is configured such that the vertical drive unit  400  includes the rotary motor  410  and the rotary shaft  420 , the coupling protrusion  314  has a through-hole  315 , into which the rotary shaft  420  having teeth is fitted to be meshed with the protrusion  314 , and the rotary shaft  420  is rotated in a predetermined direction by the rotating force from the rotary motor  410  so as to vertically reciprocate the first plate  310 , this is not intended to be limiting. 
     The first plate  310  has a penetrating opening  312  therein and a groove  313  formed along the outer circumference of the opening  312 . 
     This construction allows the second plate  320  to be fitted into the opening  312  and be rotatably coupled with the first plate  310 . 
     Here, a bearing  330  can be provided between the groove  313  and the outer circumference of the second plate  320  in order to ensure that the second plate  320  can smoothly rotate. 
     As shown in  FIGS. 3 and 4A , the second plate  320  has a central opening  322  in the central portion thereof such that both the vertical rotary shaft  120  and the rotary motor  110  of the rotary drive unit  100  can pass through the central opening  322  when the second plate  320  vertically moves together with the first plate  310 . 
     With this configuration, as shown in  FIG. 4B , when the second plate  320  vertically reciprocates, it can reach the lower end of the mirror holder  200  along the outer circumference of the rotary motor  110  without colliding into the rotary drive unit  100 . As an advantageous effect, this can reduce the size of the scanner. 
     Specifically, the displacement range of the tilt drive unit  300  is limited to the lower side of the mirror holder  200 , and the distance of displacement of the tilt drive unit  300  substantially corresponds to the length of the holder guides  220 . Therefore, the scanner can be miniaturized by controlling the size of the rotary motor  110  and the vertical rotary shaft  120  of the rotary drive unit  100 . 
     In addition, the second plate  320  has a plurality of penetrating guide holes  321  in positions corresponding to the holder guides  220  of the mirror holder  200  such that the holder guides  220  are fitted into and coupled with the guide holes  321 . 
     Therefore, as shown in  FIG. 4C , when the mirror holder  200  rotates, the holder guides  220  allow the second plate  320  and the rod  340  to rotate together with the mirror M connected with the rod  340  inside the opening  312  of the first plate  310 . 
     Since the second plate  320  moves along the holder guides  220  through the guide holes  321  when the first plate  310  vertically reciprocates, the mirror holder  200  is not influenced by the vertical reciprocation of the tilt drive unit  300 . 
     The tilt drive unit  300  can also include guide rods  317  that guide the tilt drive unit  300  to vertically reciprocate along a predetermined path. In this case, the first plate  310  has penetrating guide holes  311  in positions corresponding to the guide rods  317  to receive the guide rods  317 . 
     In addition, as shown in  FIG. 4D , the rod  340  is hinged at one end to the second plate  320  and at the other end to the mirror M such that the mirror M tilts depending on the distance of vertical displacement of the tilt drive unit  300 . 
     Particularly, the tilting range of the mirror M is determined depending on the range of vertical displacement of the rod  340 . Thus, the tilting range of the mirror M can be controlled by adjusting the distance of vertical displacement of the rod  340 . 
     Below, a description will be given of a structure of rotating and tilting the mirror of the invention with reference to  FIG. 5 . 
       FIGS. 5A and 5B  are schematic views illustrating a process of tilting the mirror of the three-dimensional scanner shown in  FIG. 3 . 
     As shown in  FIG. 5A , when the first plate  310  is moved upwards along the rotary shaft  420  by a rotating force from the rotary motor  410  of the vertical drive unit  400 , the tilt drive unit  300  moves in the right upward direction along the holder guides  220  and the guide rods  317  to reach the upper end of the holder guides  220 . 
     Then, the mirror M is pulled in the right upward direction by the rod  340  up to an inclination θ of 45 degrees or more with respect to the horizon. 
     In addition, as shown in  FIG. 5B , when the first plate  310  is moved downwards along the rotary shaft  420  by the rotating force from the rotary motor  410  of the vertical drive unit  400 , the tilt drive unit  300  moves in the right downward direction along the holder guides  220  and the guide rods  317  to reach the lower end of the holder guides  220 . 
     Then, the mirror M is pushed in the right downward direction by the rod  340  up to an inclination θ of 45 degrees or less with respect to the horizon. 
     The tilting of the mirror M is repeatedly carried out in the range 0°&lt;θ&lt;90° by the first plate  310  that is vertically reciprocating. The tilting range of the mirror M can be controlled by adjusting the range of vertical displacement of the rod  340 . 
     In addition, the rotation of the mirror M can be carried out in the same fashion by the vertical rotary shaft  120  that is continuously rotating. 
     As set forth above, the invention can obtain spatial data by scanning information on a variety of ranges of angle using a tilting structure of the mirror, which is not fixed to 45 degrees unlike the related art. 
     While the present invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims and their equivalents.