Abstract:
The invention relates to a carriage cart, which comprises a chassis frame with a front end and a rear end; a pair of front wheels mounted on the front end of the chassis frame; a pair of rear wheels mounted on the rear end of the chassis frame. The carriage cart according to example embodiments of the present invention may improve the performance of obstacle overcoming for robotic system.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to PCT/EP2014/065878 filed Jul. 24, 2014, which claims priority to EP Application No. 13180338.9 filed Aug. 14, 2013, both of which are hereby incorporated in their entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to obstacle overcoming in inspection field, in particular, to a carriage cart with obstacle overcoming for use in inspection. 
       BACKGROUND 
       [0003]    During inspection field, especially in environment not accessible by inspecting personnel, a robotic system is conventionally adopted which may carry payload such as a camera, a UT probe, a laser range scanner or other inspecting equipment. The robotic system should be provided with strong obstacle overcoming capability in order to improve the accessibility of the inspecting equipment. Generally, the robotic system comprises a carriage cart with wheels, wherein the wheels are driven by motors carried on the cart. In view of obstacle overcoming, relevant development has been proposed. 
         [0004]    A delivery trolley that may handle steps is disclosed in DE202004005391. The delivery trolley has a chassis frame supported through a leading caster wheel and at least two rear rollers. Steering arms supported by upright beams are provided in the region of the rear rollers and a walking element such as a travelling skid is associated with the at least one caster. In its rest or starting position the walking element projects forwards beyond the caster. It is swivel mounted on the chassis frame through a rod linkage to swivel about an axis aligned across the travel direction and during straight movement parallel to the caster wheel axis. Drive motors and sensors can be used to move the trolley. 
         [0005]    An arrangement in a wheel lifting mechanism designed to lift at least one wheel running on an underlying surface is disclosed in U.S. Pat. No. 7,036,185 B2, wherein the arrangement is capable of negotiating an obstacle rising above the underlying surface. The arrangement comprises an element which is formed with a contour convexly curved towards the underlying surface and is moveably supported in relation to the axle of the wheel. The said element is designed, when the contour of the element engages with the obstacle, to bring about the said lifting of the wheel as the element is rotated about its point of engagement with the obstacle. The arrangement further comprises a chassis, to which the wheel axle is firmly connected. Between the chassis and the element there is an operative connection designed, when the element engages with the obstacle, to allow the chassis firstly to undertake lifting of the wheel from a home position of the element during a displacing movement relative thereto in the direction of movement of the wheel, and secondly to bring about a return to the home position once the wheel has been lifted to the level of the obstacle. 
         [0006]    A device for facilitating driving a rollable walker of the type incorporating a chassis frame is disclosed in U.S. 20040135326A1, which is supported by at least one front wheel fitted to the depending frame part and a rear pair of wheels. The device incorporates a movable support attachable to the rollable walker in the area of its forward castor wheels and means adapted to move said movable support in front of said forward castor wheels when it/they are projecting backwards, at lifting of the said front castor wheels about the rear pair of wheels. 
         [0007]    Even great development has been achieved in the field of obstacle overcoming, there still needs a compact, low cost and easy to assembly solution that would have the ability to overcome various types of the obstacles especially in dirty environment, such as pressure vessel, cargo holds of bulk carriers, ballast tank, etc., which are common application scenario for inspection by robotic system. 
       SUMMARY 
       [0008]    It is an object of the present invention to provide a carriage cart for using in a robotic system, which may achieve obstacle overcoming with respect to various type of obstacle in a severe environment. 
         [0009]    This object is obtained by a carriage cart, comprises a chassis frame with a front end and a rear end; a pair of front wheels mounted on the front end of the chassis frame; a pair of rear wheels mounted on the rear end of the chassis frame; wherein each wheel comprises a lifting member pivotally mounted on a pivot at the same side of the chassis frame with the wheel, wherein when the carriage cart is moving in a travel direction running from the rear end to the front end of the chassis frame on a first surface by rotation of the wheel in a first rotation direction, the lifting member of the front wheel is projected beyond the front wheel in the travel direction, and wherein as the carriage cart is negotiating a second surface substantially perpendicular to the first surface, the lifting member of the front wheel contacts firstly the second surface, by which the lifting member is pivoted in a second rotation direction opposite to the first rotation direction, thereby lifting the front wheel off the first surface. 
         [0010]    According to one example embodiment of the present invention, the lifting member of the front wheel is configured to be a single piece component, and comprises a first arm extending substantially in the travel direction with a first contact end and a second arm extending substantially opposite to the first arm with a second contact end, wherein the first arm is configured to extend beyond the wheel in the travel direction so as to contact the second surface by the first contact end when the carriage cart is negotiating the second surface, and the second arm is configured to extend close to the first surface, thereby press of the first surface by the second arm at the second contact end results the lifting of the front wheel as the first contact end contacts the second surface. 
         [0011]    According to one example embodiment of the present invention, a distance between the first contact end and the first surface is greater than a distance between the pivot and the first surface. 
         [0012]    According to one example embodiment of the present invention, a distance between the first contact end and the first surface is greater than a radius of the wheel. 
         [0013]    According to one example embodiment of the present invention, a first idle wheel is disposed at the first contact end to contact and roll against the second surface when the carriage cart negotiates the second surface. 
         [0014]    According to one example embodiment of the present invention, a second idle wheel is disposed at the second contact end to contact and roll against the first surface when the carriage cart is moving on the first surface. 
         [0015]    According to one example embodiment of the present invention, the pair of the front wheel partially overlap the pair of rear wheels in the travel direction. 
         [0016]    According to one example embodiment of the present invention, the lifting member of the front wheel is configured to be a cam contour, wherein a first protrusion is provided on the cam contour serving as the first contact end to contact firstly the second surface, and a second protrusion is provided on the cam contour serving as the second contact end to contact the first surface. 
         [0017]    According to one example embodiment of the present invention, the lifting member of the rear wheel shares the same structure with that of the lifting member of the front wheel, and the lifting member of the rear wheel is symmetrical with the lifting member of the front wheel about a central vertical plane between the front wheel and the rear wheel. 
         [0018]    According to one example embodiment of the present invention, the front and rear wheels are made of ferromagnetic materials, and the first and second surface are made of ferrous materials. 
         [0019]    The carriage cart according to example embodiments of the present invention may improve the performance of obstacle overcoming for robotic system. And the carriage cart represents a low cost and easy assembly solution with high reliability for achieving obstacle overcoming in severe environment. The structure and arrangement of the carriage cart make it capable in handling various types of obstacles. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The objects, advantages and other features of the present invention will become more apparent upon reading of the following non-restrictive description of preferred embodiments thereof, given for the purpose of exemplification only, with reference to the accompany drawing, through which similar reference numerals may be used to refer to similar elements, and in which: 
           [0021]      FIG. 1  shows a schematic side view of a carriage cart according to one example embodiment of the present invention; 
           [0022]      FIG. 2  shows a schematic plan view of the carriage cart as shown in  FIG. 1 ; 
           [0023]      FIG. 3  shows a side view of a carriage cart with a lifting member according to one example embodiment of the present invention; 
           [0024]      FIG. 4  shows a partially cut-off schematic side view of another carriage cart with a lifting member according to one example embodiment of the present invention; 
           [0025]      FIG. 5  shows a partially cut-off schematic side view of another carriage cart with a lifting member according to one example embodiment of the present invention; 
           [0026]      FIG. 6  shows a schematic side view of the carriage cart with the lifting member as shown in  FIG. 5 ; 
           [0027]      FIG. 7  shows a schematic plan view of the carriage cart with the lifting member as shown in  FIG. 5 ; 
           [0028]      FIG. 8  shows a schematic side view of a carriage cart according to one example embodiment of the present invention; and 
           [0029]      FIG. 9  shows a schematic plan view of the carriage cart as shown in  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION 
       [0030]      FIG. 1  shows a schematic diagram of a carriage cart  100  according to one example embodiment of the present invention. Carriage cart  100  comprises a chassis frame  110  with a front end  112  and a rear end  114 , a pair of front wheels  120  mounted on an axis  122  on the front end  112  and a pair of rear wheels  130  mounted on an axis  132  on the rear end  114 . As shown in  FIG. 1 , the carriage cart  100  may move along a travel direction running from the rear end  114  to the front end  112  as shown by arrow  10 .  FIG. 2  shows a schematic plan view of the carriage cart  100 . In one example embodiment of the present invention, the carriage cart  100  comprises motors, not shown, for respective wheels  120 ,  130  to drive them move on a first surface  200 . 
         [0031]    According to one example embodiment, as shown in  FIG. 3 , the carriage cart  100  comprises a lifting member  140  for each wheels  120 ,  130 . For purpose of simplicity and clarity of description,  FIG. 3  shows only a part of the carriage cart  100  with only one front wheel  120  on the left side when viewed in the travel direction  10 , while the front wheel  120  on the right side is omitted for clearly showing the lifting member  140  on the right side for the front wheel  120  on the right side. As example embodiments of the present invention, the lifting member  140  for particular wheel  120 ,  130  is mounted closer to the chassis frame  110  than the particular wheel  120 ,  130 . In other words, the lifting member  140  is mounted inwardly to the chassis frame  110  from the particular wheel  120 ,  130 . 
         [0032]    As shown in  FIG. 3 , the lifting member  140  is pivotably mounted on a pivot  150  at the same side of the chassis frame  110  with the front wheel  120 , as an illustrative example. In other words, the lifting member  140  for the front wheel  120  on the right side is mounted on the right side of the chassis frame  110 , with the pivot  150  parallel to the axis  122  of the front wheel  120 . Even not shown in the drawings, it should be understood that other lifting members share similar arrangement with their respective wheels. With reference to  FIG. 3 , the lifting member  140  projects beyond the front wheel  120  substantially in the travel direction  10 . Thus, when the carriage cart  100  is negotiating a second surface  300  that is substantially perpendicular to the first surface  200 , the lifting member  140  will contact firstly the second surface  300  than the front wheel  120 . In other words, the lifting member  140  contacts the second surface  300  earlier than the front wheel  120 . As shown in  FIG. 3 , the lifting member  170  for the rear wheel  130  shares the same structure with that of the lifter member  140  for the front wheel  120 . However, the lifting member  170  for the rear wheel  130  is symmetrical with the lifting member  140  for the front wheel  120  about a central vertical plane between the front wheels  120  and the rear wheels  130 . As shown in  FIG. 3 , the lifting member  170  is pivotably mounted on a pivot  180  at the same side of the chassis frame  110  with the rear wheel  130 . 
         [0033]    As one example embodiment of the present invention, as shown in  FIG. 3 , the lifting member  140  is configured to be a single piece component, and comprises a first arm  142  extending substantially in the travel direction  10 , with a first contact end  146 , and a second arm  144  extending substantially opposite to the first arm  142 , with a second contact end  148 . It is seen from  FIG. 3 , the first contact end  146  of the first arm  142  extends beyond the front wheel  120  in the travel direction  10  so as to contact the second surface  300  by the first contact end  146  when the carriage cart  100  is negotiating the second surface  300 . Furthermore, the second arm  144  is configured to extend close to the first surface  200  when the carriage cart  100  is moving on the first surface  200 . For example, when the carriage cart  100  moving on the first surface  200  by the rotation of the wheels  120 ,  130  in clockwise direction is negotiating the second surface  300 , the first contact end  146  of first arm  142  of the lifting member  140  will impact the second surface  300  with the drive of the not shown motors applied to the wheels  120 ,  130 , by which the lifting member  140  will pivot about the pivot  150  in counterclockwise direction, thereby the second contact end  148  of the second arm  144  of the lifting member  140  will be pressed against the first surface  200 , resulting lifting of the front wheel  120 , i.e. the chassis frame  110  along with the front wheel  120  will pivot about the contact point of the rear wheel  130  with the first surface  200  in a counterclockwise direction. The operation of the lifting member  140  will prevent stuck of the front wheel  120  against the second surface  300  when the carriage cart  100  is negotiating the second surface  300 . Then, the front wheel  120  will move with the drive of the not shown motors and contact the second surface  300 , by which the movement of the carriage cart will continue on the second surface  300 . As shown in  FIG. 3 , the lifting member  170  is also configured to be a single piece component, and comprises a first arm  172  extending substantially in a direction opposite the travel direction  10 , with a first contact end  176 , and a second arm  174  extending substantially opposite to the first arm  172 , with a second contact end  178 . 
         [0034]    It should be noted that, since the lifting member  170  shares the same structure with that of the lifting member  140 , the structural features as detailed hereafter equally apply to the lifting member  170 . For purpose of simplicity and clarity, the below description takes only the lifting member  140  as an example. 
         [0035]    As one example embodiment of the present invention, the wheels  120 ,  130  of the carriage cart  100  are made of ferromagnetic materials, and the first and second surfaces  200 ,  300  are made of ferrous materials. The magnetic bond of the carriage cart  100  by the wheels  120 ,  130  to the second surface  300  will prevent drop of the carriage cart  100  when it is moving on the second surface  300 . At the same time, the magnetic bond of the wheels  120 ,  130  to the first surface  200  contributes to the stuck of the carriage cart  100  when it is negotiating the second surface  300 . With the operation of the lifting member  140 , lifting of the front wheel  120  will facilitate release of the carriage cart  100  from the first surface  200  hence reduction of the magnetic bond therebetween and prevent stuck of the carriage cart  100  against the second surface  300 . While the front wheel  120  will contact and adhere to the second surface  300  after lifting of the front wheel  120 , thereby facilitating transition of the movement of the carriage cart  100  from the first surface  200  to the second surface  300 , improving its obstacle overcoming capability. According to one example embodiment, the lifting member  140  may be combined with two rollers or bearings which are in contact with the surface, allowing for a smooth transition from one surface to the next of the carriage cart  100 . 
         [0036]    As one example embodiment of the present invention, the distance of the first contact end  146  and the first surface  200  is greater than a distance between the pivot  150  and the first surface  200 . This will facilitate pivot of the lifting member  140  in the opposite direction to the rotation of the front wheel  120 . As alternative embodiment, the distance between the first contact end  146  and the first surface  200  is greater than a radius of the wheel. This will further facilitate the pivot of the lifting member  140  in the opposite direction to the rotation of the front wheel  120 . 
         [0037]    As alternative embodiment of the present invention shown in  FIG. 4 , the first contact end  146  of the first arm  142  of the lifting member  140  may be provided with an idle wheel  147 , which will contact and roll on the second surface  300  when the carriage cart  100  is negotiating the second surface  300 , thereby reducing friction and facilitating pivot of the lifting member  140  hence facilitating lifting of the front wheel  120 . In addition, the second contact end  148  of the second arm  144  of the lifting member  140  may also be provided with an idle wheel  149 , which may roll on the first surface as the carriage cart  100  is moving on the first surface  200 . Furthermore, when the carriage cart  100  is negotiating the second surface  300  and the first arm  142  of the lifting member  140  is contacting the second surface  300  by the idle wheel  147 , the idle wheel  149  may press the first surface  200  so as to lifting the front wheel  120 . 
         [0038]    As another example embodiment shown in  FIG. 5 , the lifting member  140  may be configured to be a cam contour  240 . With reference to  FIG. 5 , cam contour  240  may consists of a first portion  242  with a protrusion  246  beyond the front wheel  120  in the travel direction  10 , and a second portion  244  with a protrusion  248  extending substantially close to the first surface  200  as the carriage cart  100  is moving on the first surface  200 . The cam contour  240  is pivotablly attached to the chassis frame  110  of the carriage cart  100  at the pivot  250 . As described above, similar to the lifting member  140  described with reference to  FIG. 3 , when the carriage cart  100  is negotiating the second surface  300  as moving on the first surface  200 , the cam contour  240  may contact the second surface  300  firstly by means of the protrusion  246 , by which the cam contour  240  will pivot around pivot  250  in counterclockwise direction that is opposite to the rotation direction of the front wheel  120 , thereby the protrusion  248  of the cam contour  240  will press the first surface  200  and lifting the front wheel  120 . As stated above, the lifting member  170  may be also configured to be another cam contour  270  (shown in  FIG. 6 ) that shares the same structure with that of the cam contour  240 . However, the cam contour  270  is symmetrical with the cam contour  240  about the central vertical plane between the front wheel  120  and the rear wheel  130 . 
         [0039]      FIG. 6  shows a side view of the carriage cart  100  with the cam contours  240  for each front wheels  120 , and cam contour  270  for each rear wheels  130 . As shown in  FIG. 6 , the cam contour  240  for front wheels  120  and the cam contour  270  for rear wheels  130  on the right side as viewed in the travel direction  10  is shown, with the front wheels  120  and rear wheels  130  on the right side omitted for clarity.  FIG. 7  shows the plan view of the carriage cart  100 , wherein all cam contours  240 ,  270  are presented for easy understanding their positions relating to the front and rear wheels  120 ,  130  and the chassis frame  110 . 
         [0040]    As another alternative embodiment not shown in the drawings, an idle wheel may be provided also to the protrusion  246 ,  248  in order to facilitate operation of the cam contour. The structure and arrangement of the idle wheel may be similar to that as described above with reference to  FIG. 4 , from which those skilled in the art will appreciate. 
         [0041]    In another aspect of the present invention, one example embodiment is shown in  FIG. 8 , where the carriage cart  100  comprises a pair of front wheels  120  and a pair of rear wheels  130 . As shown in  FIG. 8 , the pair of the front wheels  120  partially overlaps the pair of the rear wheels  130  in the travel direction  10 . As such, the carriage cart  100  is capable overcome an “I” shape obstacle  400  as shown by phantom line in  FIG. 8 . In this case, the rear wheels  130  may be provided with a larger distance in the axis  132  than that of the front wheels  120  in the axis  122  in order to avoid interference, as shown in  FIG. 9 . 
         [0042]    As another example embodiment that is not shown in the drawings, the carriage cart  100  as shown in  FIG. 8  may also comprises the lifting member  140 ,  170  or cam contour  240 ,  270  as shown in  FIG. 3  or  FIG. 5  in order to achieve the technical effect when negotiate the second surface. 
         [0043]    While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.