Patent Publication Number: US-2022221871-A1

Title: Unmanned vehicle path control method, apparatus, and system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a U.S. National Stage Application under 35 U.S.C. § 371 of International Patent Application No. PCT/CN2020/080866, filed on Mar. 24, 2020, which is based on and claims priority from CN application No. 201910411149.1, filed on May 17, 2019, the disclosure of both of which are hereby incorporated into this disclosure by reference in its entirety 
    
    
     TECHNICAL FIELD 
     The disclosure relates to the field of path planning, and in particular relates to a method, a device and a system for controlling a path of an unmanned vehicle. 
     BACKGROUND 
     In the prior art, automated equipment such as unmanned vehicles have been widely used in warehouse management and production. By providing one-way landmarks on a lane between adjacent shelves and the main road convenient for the unmanned vehicle to pass through, and it can be ensured that the unmanned vehicle moves in a preset path by identifying the one-way landmarks. 
     SUMMARY 
     According to a first aspect of an embodiment of the present disclosure, there is provided a method for controlling a path of an unmanned vehicle, comprising: querying a current position and a target position of the unmanned vehicle; performing path planning according to the current position, the target position and advancing directions indicated by landmarks disposed on two sides of roads to obtain a planned path with a minimum path cost, wherein the unmanned vehicle moves forward on a predetermined side of a road; and transmitting the planned path to the unmanned vehicle, thereby the unmanned vehicle reaching the target position according to the planned path. 
     In some embodiments, the performing path planning according to the current position, the target position and advancing directions indicated by landmarks disposed on two sides of the roads comprises: determining whether the current position and the target position are both located in a first lane in the roads; determining whether the unmanned vehicle can reach the target position by moving straight forward without turning around according to an advancing direction indicated by a landmark corresponding to the current position under a condition that the current position and the target position are both located in a first lane; and planning a first path according to the current position, the target position and an advancing direction indicated by the landmark disposed on the predetermined side of the first lane under a condition that the unmanned vehicle can reach the target position by moving straight forward without turning around, thereby the unmanned vehicle moving straight forward from the current position to reach the target position according to the first path. 
     In some embodiments, detecting a type of the landmark corresponding to the current position under a condition that the unmanned vehicle reaches the target position by turning around; and planning a second path according to the current position, the target position and advancing directions indicated by the landmarks disposed on two sides of the first lane under a condition that the type of the landmark corresponding to the current position is a first-type of the landmark, thereby the unmanned vehicle turning around at the current position to reach the target position according to the second path, wherein the first-type of the landmark comprises a first advancing direction for turning around. 
     In some embodiments, determining a turning-around position according to the current position, the target position and the advancing direction of the landmark corresponding to the current position under a condition that the type of the landmark corresponding to the current position is a second-type of the landmark, thereby the unmanned vehicle directly reaching the target position, or moving straight forward to reach the target position, after turning around from the turning-around position to another side of the lane, wherein the second-type of the landmark comprises a second advancing direction for moving straight forward and a third advancing direction for turning around; determining whether the turning-around position coincides with the current position; and planning a third path according to the current position, the target position and the advancing directions indicated by landmarks disposed on two sides of the first lane under a condition that the turning-around position coincides with the current position, thereby the unmanned vehicle turning around at the current position to reach the target position according to the third path. 
     In some embodiments, planning a fourth path according to the current position, the turning-around position, the target position, and the advancing directions indicated by the landmarks disposed on two sides of the first lane under a condition that the turning-around position does not coincide with the current position, thereby the unmanned vehicle moving straight forward from the current position to the turning-around position and turning around at the turning-around position to reach the target position according to the fourth path. 
     In some embodiments, selecting a first lane opening corresponding to the current location and a second lane opening corresponding to the target location according to the current location and the target location under a condition that the current location is within the first lane and the target location is within a second lane in the roads, wherein a lane opening is an intersection area between an exit of a corresponding lane and a main road in the roads; and planning a fifth path according to the current position, the target position, advancing directions indicated by the landmarks disposed in the first lane opening, the advancing directions indicated by the landmarks disposed at two sides of the first lane and the advancing directions indicated by the landmarks disposed at two sides of the second lane under a condition that the first lane opening coincides with the second lane opening, thereby the unmanned vehicle entering the first lane opening from the current position, moving straight forward to pass through the first lane opening and entering the second lane to reach the target position according to the fifth path. 
     In some embodiments, planning a sixth path according to the current position, the target position, the advancing directions indicated by the landmarks disposed in the first lane opening, advancing directions indicated by landmarks disposed in the second lane opening, advancing directions indicated by landmarks disposed on two sides of a first main road between the first lane opening and the second lane opening, the advancing directions indicated by the landmarks disposed on two sides of the first lane, and advancing directions indicated by landmarks disposed on two sides of the second lane under a condition that the first lane opening does not coincide with the second lane opening, thereby the unmanned vehicle entering the first lane opening from the current position, turning from the first lane opening into the first main road, entering the second lane opening from the first main road, and entering the second lane from the second lane opening to reach the target position according to the sixth path. 
     In some embodiments, selecting a third lane opening corresponding to the target position according to the current position and the target position under a condition that the current position is within a second main road in the roads and the target position is within in a third lane in the roads; and planning a seventh path according to the current position, the target position, advancing directions indicated by the landmarks disposed at two sides of the second main road, advancing directions indicated by the landmarks disposed in the third lane opening and advancing directions indicated by the landmarks disposed at two sides of the third lane, thereby the unmanned vehicle entering the third lane opening from the current position and entering the third lane from the third lane opening to reach the target position according to the seventh path. 
     In some embodiments, each lane opening includes four third-type landmarks, each third-type landmark comprises a fourth advancing direction for moving straight forward and a fifth advancing direction for turning around, the unmanned vehicle can cyclically move between positions corresponding to the four third-type landmarks in each lane opening. 
     In some embodiments, controlling the unmanned vehicle to reach a first position corresponding to a first landmark in a predetermined lane opening under a condition that the unmanned vehicle moving straight forward through a predetermined lane opening; controlling the unmanned vehicle to move straight forward from the first position to reach a second position corresponding to a second landmark in the predetermined lane opening; and controlling the unmanned vehicle to move straight forward from the second position to pass through the predetermined lane opening. 
     In some embodiments, controlling the unmanned vehicle to reach a first position corresponding to the first landmark in the predetermined lane opening under a condition that the unmanned vehicle turning to a predetermined side through a predetermined lane opening; and controlling the unmanned vehicle to turn from the first position to the predetermined side, thereby the unmanned vehicle turning to the predetermined side through the predetermined lane opening. 
     In some embodiments, controlling the unmanned vehicle to reach a first position corresponding to the first landmark in the predetermined lane opening under a condition that the unmanned vehicle turning to an opposite side of the predetermined side through a predetermined lane opening; controlling the unmanned vehicle to move straight forward from the first position to reach a second position corresponding to the second landmark in the predetermined lane opening; controlling the unmanned vehicle to turn from the second position to the opposite side of the predetermined side to reach a third position corresponding to a third landmark in a predetermined lane opening; and controlling the unmanned vehicle to move straight forward from the third position, thereby the unmanned vehicle turning to an opposite side of the predetermined side through the predetermined lane opening. 
     In some embodiments, the querying the current position of the unmanned vehicle comprises: determining the current position of the unmanned vehicle according to a landmark information on the current position of the unmanned vehicle. 
     According to a second aspect of the embodiments of the present disclosure, there is provided an apparatus for controlling a path of an unmanned vehicle, comprising: a memory configured to store instructions; a processor coupled to the memory, wherein based on the instructions stored in the memory, the processor is configured to implement: query a current position and a target position of the unmanned vehicle; perform path planning according to the current position, the target position and advancing directions indicated by landmarks disposed on two sides of roads to obtain a planned path with a minimum path cost, wherein the unmanned vehicle moves forward on a predetermined side of a road; and transmit the planned path to the unmanned vehicle, thereby the unmanned vehicle reaching the target position according to the planned path. 
     According to a third aspect of the embodiments of the present disclosure, there is provided an system for controlling a path of an unmanned vehicle, comprising: an apparatus for controlling a path of an unmanned vehicle according to any one of the embodiments described above, and an unmanned vehicle, configured to transmit landmark information on a current position to the apparatus, thereby the apparatus planning a path from the current position to a target position of the unmanned vehicle, and configured to move to the target position according to a planned path transmitted by the apparatus. 
     In some embodiments, the unmanned vehicle is further configured to identify landmark information of landmarks disposed on two sides of roads during moving to the target position according to the planned path, compare identified landmark information with the planned path, and transmit the landmark information at the current position to the apparatus under a condition that the identified landmark information does not consistent with the planned path, thereby the apparatus replanning a path from the current position to the target position. 
     According to a fourth aspect of the embodiments of the present disclosure, there is provided a non-transitory computer-readable storage medium, wherein the computer readable storage medium stores computer instructions which, when executed by a processor, cause the processor to implement: query a current position and a target position of the unmanned vehicle; perform path planning according to the current position, the target position and advancing directions indicated by landmarks disposed on two sides of roads to obtain a planned path with a minimum path cost, wherein the unmanned vehicle moves forward on a predetermined side of a road; and transmit the planned path to the unmanned vehicle, thereby the unmanned vehicle reaching the target position according to the planned path. 
     Other features of the present disclosure and advantages thereof will become apparent from the following detailed description of exemplary embodiments thereof, which proceeds with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below. Apparently, the drawings in the following description are only some of the embodiments of the present disclosure, and for those skilled in the art, other drawings may be obtained according to the drawings without paying inventive effort. 
         FIG. 1  is a schematic flow chart of a method for controlling a path of an unmanned vehicle according to one embodiment of the present disclosure; 
         FIG. 2  is a schematic diagram of an application scenario of one embodiment of the present disclosure; 
         FIG. 3  is a schematic diagram of an application scenario of another embodiment of the present disclosure; 
         FIG. 4  is a schematic illustration of an application scenario of still another embodiment of the present disclosure; 
         FIG. 5  is a schematic illustration of an application scenario of still another embodiment of the present disclosure; 
         FIG. 6  is a schematic illustration of an application scenario of still another embodiment of the present disclosure; 
         FIG. 7  is a schematic illustration of an application scenario of still another embodiment of the present disclosure; 
         FIG. 8  is a schematic structural view of an apparatus for controlling a path of an unmanned vehicle according to one embodiment of the present disclosure; 
         FIG. 9  is a schematic structural view of an apparatus for controlling a path of an unmanned vehicle according to another embodiment of the present disclosure; 
         FIG. 10  is a schematic structural view of an system for controlling a path of an unmanned vehicle according to another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The technical solutions in the embodiments of the present disclosure will be described clearly and completely with reference to the drawings in the embodiments of the present disclosure, and it is obvious that the embodiments described are only some, instead of all, of the embodiments of the present disclosure. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments disclosed herein without inventive step, are intended to be within the scope of the present disclosure. 
     The relative arrangement of parts and steps, numerical expressions and values set forth in these embodiments do not limit the scope of the present disclosure unless specifically stated otherwise. 
     Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. 
     Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. 
     In all examples shown and discussed herein, any particular value should be construed as exemplary only and not as limiting. Thus, other examples of the exemplary embodiments may have different values. 
     It should be noted that similar reference signs and letters refer to similar items in the following figures, and thus, once an item is defined in one figure, it need not be discussed further in subsequent figures. 
     The inventors found through research that congestion is likely to occur because only one-way landmarks are provided on the lanes and the main roads, i.e., unmanned vehicles traveling in different directions use the same landmark. At the lane exit, there are lots of unmanned vehicles moving straight forward, turning left or turning right, which intensifies the condition of traffic jam and seriously affects working efficiency. 
     To this end, the present disclosure provides an unmanned vehicle path control scheme that reduces congestion conditions. 
       FIG. 1  is a schematic flow chart of a method for controlling a path of an unmanned vehicle according to one embodiment of the present disclosure. In some embodiments, the following steps of the method for controlling the path of the unmanned vehicle are performed by an apparatus for controlling the path of the unmanned vehicle. 
     In step  101 , a current position and a target position of the unmanned vehicle are queried. 
     In some embodiments, the current position of the unmanned vehicle is determined based on landmark information on the current position of the unmanned vehicle. 
     In step  102 , path planning is performed according to the current position, the target position and advancing directions indicated by landmarks disposed on two sides of roads to obtain a planned path with a minimum path cost, wherein the unmanned vehicle moves forward on a predetermined side of a road. 
       FIG. 2  is a schematic diagram of an application scenario according to an embodiment of the present disclosure. Here, the roads on which the unmanned vehicle passes is a bidirectional road, and landmarks indicating the moving direction of the unmanned vehicle are disposed on two sides of the road. The unmanned vehicle approaches a predetermined side of the road when moving forward, for example, the unmanned vehicle always approaches the right side of the road when moving forward. The roads comprises lanes and main roads, the lane is disposed between the adjacent shelves, and an intersection area between the exit of a lane and a main road is the lane opening. 
     As shown in  FIG. 2 , a road between adjacent shelves  11  is a lane  12 . The intersection between the exit of the lane  12  and the main road  13  is a lane opening  14 . The lane  12  and the main road  13  are provided with landmarks  15  for the two-way moving of an unmanned vehicle. 
     In step  103 , the planned path is transmitted to the unmanned vehicle, thereby the unmanned vehicle reaching the target position according to the planned path. 
     In the method for controlling the path of the unmanned vehicle provided by the above embodiment of the disclosure, the lanes and the main roads in the warehouse are both set as bidirectional roads, so that the unmanned vehicles in different moving directions can conveniently move on different roads, and the road congestion is effectively reduced. 
       FIG. 3  is a schematic diagram of an application scenario of another embodiment of the present disclosure. As shown in  FIG. 3 , there are three types of landmarks provided on the lanes and the main roads. For simplicity, only part of the landmark types are labeled in  FIG. 3 . 
     The landmarks contained in the box  21  are first-type landmarks, also called two-way landmarks. 
     A two-way landmark, i.e. an edge landmark, has only two landmarks adjacent to it. The two-way landmark includes an inlet direction and a forward direction. That is, of the two landmarks adjacent to the two-way landmark, the unmanned vehicle moves from the position corresponding to one of the adjacent landmarks to the position corresponding to the two-way landmark along the inlet direction, and moves from the position corresponding to the two-way landmark to the position corresponding to the other adjacent landmark along the forward direction. 
     For example, the format information of the two-way landmark is: [X, Y, landmark KEY, Up_NONE_NONE, Down_Inlet_landmark KEY, Left_Outlet_landmark KEY, Right_NONE_NONE], where X, Y represents coordinates of a two-way landmark, the landmark KEY is related information of the landmark, and the up, lower, left or right represents adjacent positions, the Down_Inlet_landmark KEY indicates that an unmanned vehicle can move from a position corresponding to a landmark located below the two-way landmark to a position corresponding to the two-way landmark, and the Left_Outlet_landmark KEY indicates that the unmanned vehicle can move from the position corresponding to the two-way landmark to a position corresponding to the adjacent landmark to the left. 
     Since the inlet and outlet of a two-way landmark are both unidirectional, and the unmanned vehicle on the two-way landmark has only one advancing direction, the unmanned vehicle thereby passes the position corresponding to the two-way landmark in accordance with the advancing direction. 
     The landmarks included in box  22  are landmarks of a second-type, also known as three-way landmarks. 
     The three-way landmarks have three adjacent landmarks. A three-way landmark includes an inlet direction, a second advancing direction for moving straight forward, and a third advancing direction for turning around. The unmanned vehicle can move from the position corresponding to the first adjacent landmark to the position corresponding to the current three-way landmark, and can move forward from the position corresponding to the current three-way landmark to the position corresponding to the second adjacent landmark. In addition, the unmanned vehicle is also able to traverse between a location corresponding to the current three-way landmark and a location corresponding to a third adjacent landmark (also a three-way landmark). 
     For example, the format information of the three-way landmark is: [X, Y, Landmark KEY, Up_Inlet_Landmark KEY, Down_Outlet_Landmark KEY, Left_NONE_NONE, Right_Inlet/Outlet_Landmark KEY]. 
     Since the inlet and the outlet of the three-way landmark are both bidirectional, the unmanned vehicle can turn around when needed. 
     The landmarks included in box  23  are landmarks of a third-type, also known as four-way landmarks. 
     The lane opening can be regarded as a crossroad, and four four-way landmarks are disposed in each lane opening. The four-way landmark includes two inlet directions, a fourth advancing direction for moving straight forward and a fifth advancing direction for turning around. The unmanned vehicle is able to cyclically move between positions corresponding to the four landmarks in each lane opening. The four-way landmark has four adjacent landmarks at the up, down, left and right sides, and the unmanned vehicle can move to the position corresponding to the adjacent landmark of the current four-way landmark through the positions corresponding to the two adjacent landmarks and also can move to the positions corresponding to the other two adjacent landmarks from the position corresponding to the current four-way landmark. 
     For example, the format information of the four-way landmark is: [X, Y, Landmark KEY, Up_Inlet_Landmark KEY, Down_Outlet_Landmark KEY, left_Outlet_Landmark KEY, Right_Inlet_Landmark KEY]. 
     As shown in  FIG. 3 , in a lane opening, four four-way landmarks can form a counterclockwise cycle, so that the unmanned vehicle can realize various direction adjustments at the lane opening, and the occurrence of congestion can be effectively avoided. 
       FIG. 4  is a schematic diagram of an application scenario of another embodiment of the present disclosure. 
     As shown on the right side of  FIG. 4 , in a case where an unmanned vehicle needs to move straight through a lane opening, the unmanned vehicle first arrives at a first position corresponding to a first landmark in the lane opening from a landmark  31 . The unmanned vehicle continues to move straight from the first position to a second position corresponding to a second landmark in the lane opening. The unmanned vehicle continues to move straight from the second position to reach the location of the landmark  32  to realize straight through the lane opening. The corresponding path is shown as path  41 . 
     As shown in the middle of  FIG. 4 , in a case where an unmanned vehicle needs to turn right through a lane opening, the unmanned vehicle first arrives at a first position corresponding to a first landmark in the lane opening from the landmark  33 . The unmanned vehicle turns to the right from the first position to reach the location of the landmark  34  to realize a right turn through the lane opening. The corresponding path is shown as path  42 . 
     As shown on the left side of  FIG. 4 , in a case where an unmanned vehicle needs to turn to the left through a lane opening, the unmanned vehicle first arrives at a first position corresponding to a first landmark in the lane opening from a landmark  35 . The unmanned vehicle continues to move straight from the first position to a second position corresponding to a second landmark in the lane opening. The unmanned vehicle turns left from the second position and reaches a third position corresponding to a third landmark in the lane opening. The unmanned vehicle continues to move straight from the third position to reach the location of the landmark  36  to realize a left turn through the lane opening. The corresponding path is shown as path  43 . 
       FIG. 5  is a schematic diagram of an application scenario of another embodiment of the present disclosure. 
     As shown in  FIG. 5 , in some embodiments, a first path is planned according to the current position, the target position and an advancing direction indicated by the landmark disposed on the predetermined side of the lane under a condition that the current position and the target position are both located in a same lane, and the unmanned vehicle can reach the target position by moving straight forward without turning around, thereby the unmanned vehicle moving straight forward from the current position to reach the target position according to the first path. 
     As shown in the upper right portion of  FIG. 5 , the unmanned vehicle needs to move from a position corresponding to the landmark  51  to a position corresponding to the landmark  52 . Since the unmanned vehicle moves straight ahead to reach the target position, the path  501  can be planned directly between the landmark  51  and the landmark  52 . 
     In some embodiments, a type of the landmark corresponding to the current position is detected under a condition that the current position and the target position are located in the same lane and the unmanned vehicle can reach the target position by turning around. If the type of the landmark corresponding to the current position is a two-way landmark, the unmanned vehicle must turn around. A second path is planned according to the current position, the target position and advancing directions indicated by the landmarks disposed on two sides of the lane, thereby the unmanned vehicle turning around at the current position to reach the target position according to the second path. 
     As shown in the upper left portion of  FIG. 5 , the unmanned vehicle needs to move from a position corresponding to the landmark  53  to a position corresponding to the landmark  55 . Since the landmark  53  is a two-way landmark, the unmanned vehicle must turn around to reach the target location, therefore a path  502  can be planned between the landmark  53 , the landmark  54 , and the landmark  55 . 
     In some embodiments, the current position and the target position are located in the same lane, and the unmanned vehicle reaches the target position by turning around. A turning-around position is determined according to the current position and the target position under a condition that the type of the landmark corresponding to the current position is a three-way landmark, wherein the unmanned vehicle can directly reach the target position, or move straight forward to reach the target position, after turning around from the turning-around position to another side of the lane. A third path is planned according to the current position, the target position and the advancing directions indicated by landmarks disposed on two sides of the lane under a condition that the turning-around position coincides with the current position, thereby the unmanned vehicle turning around at the current position to reach the target position according to the third path. A fourth path is planned according to the current position, the turning-around position, the target position, and the advancing directions indicated by the landmarks disposed on two sides of the lane under a condition that the turning-around position does not coincide with the current position, thereby the unmanned vehicle moving straight forward from the current position to the turning-around position and turning around at the turning-around position to reach the target position according to the fourth path. 
     As shown in the lower right portion of  FIG. 5 , the landmark  56  and the landmark  58  are located on two sides of the road, and the unmanned vehicle needs to turn around to reach the location of the landmark  58 . Because the unmanned vehicle can reach the landmark  58  by turning around at the landmark  56  where the unmanned vehicle is currently located, and the landmark  56  is a three-way landmark, the path  503  can be planned between the landmark  56 , the landmark  57  and the landmark  58 . 
     In the lower left portion of  FIG. 5 , landmark  59  and landmark  511  are located on two sides of the road, and the unmanned vehicle needs to turn around to reach the location of landmark  511 . Although the landmark  59  is a three-way landmark, the unmanned vehicle cannot reach the landmark  511  after turning around at the landmark  59 . Therefore, the unmanned vehicle needs to move to landmark  510  firstly. The landmark  510  is also a three-way landmark, therefore the unmanned vehicle can turn around from landmark  510  to reach landmark  511 . Path  504  may thus be planned between landmark  59 , landmark  510 , and landmark  511 . 
       FIG. 6  is a schematic diagram of an application scenario of another embodiment of the present disclosure. 
     In some embodiments, as shown in  FIG. 6 , the current position is located in a first lane and the target position is located in a second lane, a first lane opening corresponding to the current position and a second lane opening corresponding to the target position are selected according to the current position and the target position. A fifth path is planned according to the current position, the target position, advancing directions indicated by the landmarks disposed in the first lane opening, the advancing directions indicated by the landmarks disposed at two sides of the first lane and the advancing directions indicated by the landmarks disposed at two sides of the second lane under a condition that the first lane opening coincides with the second lane opening, thereby the unmanned vehicle entering the first lane opening from the current position, moving straight forward to pass through the first lane opening and entering the second lane where the targe position is located to reach the target position according to the fifth path. 
     As shown in the right part of  FIG. 6 , the unmanned vehicle needs to move from a position corresponding to the landmark  61  to a position corresponding to the landmark  62 . Since the lane opening for leaving the lane where the landmark  61  is located is the same lane opening for entering the lane where the landmark  62  is located, path  601  can be planned using landmark  61 , lane opening a 1  and landmark  62 . 
     In some embodiments, upon selection of a first lane opening corresponding to the current location and a second lane opening corresponding to the target location, a sixth path is planned according to the current position, the target position, the advancing directions indicated by the landmarks disposed in the first lane opening, advancing directions indicated by landmarks disposed in the second lane opening, advancing directions indicated by landmarks disposed on two sides of a main road between the first lane opening and the second lane opening, the advancing directions indicated by the landmarks disposed on two sides of the first lane, and advancing directions indicated by landmarks disposed on two sides of the second lane under a condition that the first lane opening does not coincide with the second lane opening, thereby the unmanned vehicle entering the first lane opening from the current position, turning from the first lane opening into the second lane opening, and entering the second lane from the second lane opening to reach the target position according to the sixth path. 
     As shown in the left part of  FIG. 6 , the unmanned vehicle needs to move from a position corresponding to the landmark  63  to a position corresponding to the landmark  64 . Since a lane opening a 3  for leaving the lane where the landmark  63  is located is not the same as the lane opening a 4  for entering the lane were the landmark  64  is located, path  602  can be planned using landmark  63 , lane opening a 3 , lane opening a 2  and landmark  64 . 
     In some embodiments, a third lane opening corresponding to the target position is selected according to the current position and the target position under a condition that the current position is within a main road in the roads and the target position is within in a third lane. A seventh path is planned according to the current position, the target position, advancing directions indicated by the landmarks disposed at two sides of the main road, advancing directions indicated by the landmarks disposed in the third lane opening and advancing directions indicated by the landmarks disposed at two sides of the third lane, thereby the unmanned vehicle entering the third lane opening from the current position and entering the third lane from the third lane opening to reach the target position according to the seventh path. 
     As shown in the left portion of  FIG. 6 , the unmanned vehicle needs to move from landmark  65  to landmark  66 . Landmark  65  is located on the main road. The unmanned vehicle moves to the landmark  66  according to the landmark  65 , and selects a lane opening a 2  corresponding to the landmark  66 . Path  603  is thus planned depending on landmark  65 , lane opening a 2  and landmark  66 . 
       FIG. 7  is a schematic diagram of an application scenario of still another embodiment of the present disclosure. As shown in  FIG. 7 , the unmanned vehicle is initially located at the position corresponding to the landmark with coordinates (9, 4), and needs to sequentially reach the positions corresponding to the landmarks with coordinates (5, 1), (4, 2), (2, 0) , (1, 1), and (1, 7). 
     According to the embodiments of  FIGS. 1 to 6 , in the process that the unmanned vehicle arrives at the landmark with the coordinates (5, 1) from the landmark with the coordinates (9, 4) , the corresponding information of the landmarks it passes is as follows:
     [9,  4 , KEY/9/4, Up_NONE_NONE, Down_Inlet KEY/9/5, Left_Outlet_KEY/8/5, Right_NONE_NONE ];   [8, 4, KEY/8/4, Up_Outlet_KEY/8/3, Down_Inlet_KEY/8/5, Left_Outlet_KEY/7/4, Right_Inlet_KEY/9/4];   . . .   [5, 2, KEY/5/2, Up_Outlet_KEY/5/1, Down_Inlet_KEY/5/3, Left_Inlet/Outlet_KEY/4/2, Right_NONE_NONE];   [5,  1 , KEY/5/1, Up_Outlet_KEY/5/0, Down_Inlet_KEY/5/2, Left_Inlet/Outlet_KEY/4/1, Right_NONE_NONE].   

     Accordingly, after the unmanned vehicle reaches the landmark with the coordinates (5, 1), the landmarks with the coordinates (4, 2), (2, 0), (1, 1) and (1, 7) may also be reached sequentially according to the embodiments of  FIGS. 1 to 6 . 
       FIG. 8  is a schematic structural view of an apparatus for controlling a path of an unmanned vehicle according to one embodiment of the present disclosure. As shown in  FIG. 8 , the apparatus includes an querying module  81 , a path planning module  82 , and a transmitting module  83 . 
     The querying module  81  is configured to query a current position and a target position of the unmanned vehicle. 
     The path planning module  82  is configured to perform path planning according to the current position, the target position and advancing directions indicated by landmarks disposed on two sides of the roads to obtain a planned path with a minimum path cost, wherein the unmanned vehicle moves forward on a predetermined side of a road. 
     In some embodiments, the path planning module  82  performs path planning according to the embodiments illustrated in  FIGS. 2-7 . 
     The sending module  83  is configured to transmit the planned path to the unmanned vehicle, thereby the unmanned vehicle reaching the target position according to the planned path. 
     In the apparatus for controlling the path of the unmanned vehicle provided by the above embodiment of the present disclosure, the lane and the main road in the warehouse are both set as bidirectional roads, so that unmanned vehicles in different moving directions can move on different roads, and the road congestion is effectively reduced. 
       FIG. 9  is a schematic structural view of an apparatus for controlling the path of the unmanned vehicle according to another embodiment of the present disclosure. As shown in  FIG. 9 , the apparatus includes a memory  91  and a processor  92 . 
     The memory  91  is used for storing instructions, the processor  92  is coupled to the memory  91 , and the processor  92  is configured to execute the method according to any one of  FIGS. 1 to 7  based on the instructions stored in the memory. 
     As shown in  FIG. 9 , the apparatus for controlling the path of the unmanned vehicle further includes a communication interface  93  for information interaction with other devices. Meanwhile, the apparatus for controlling the path of the unmanned vehicle further comprises a bus  94 , and the processor  92 , the communication interface  93  and the memory  91  communicate with each other through the bus  94 . 
     The memory  91  may comprise high-speed RAM memory, and may also include non-volatile memory, such as at least one disk memory. The memory  91  may also be a memory array. The storage  91  may also be partitioned and the blocks may be combined into virtual volumes according to certain rules. 
     Further, the processor  92  may be a central processing unit CPU, or may be an application specific integrated circuit ASIC, or one or more integrated circuits configured to implement embodiments of the present disclosure. 
     The present disclosure also relates to a computer-readable storage medium, in which computer instructions are stored, and when executed by a processor, the instructions implement the method according to any one of  FIGS. 1 to 7 . 
       FIG. 10  is a schematic structural view of an system for controlling a path of a unmanned vehicle according to an embodiment of the present disclosure. As shown in  FIG. 10 , the apparatus for controlling the path of the unmanned vehicle includes an unmanned vehicle path control device  1001  and an unmanned vehicle  1002 . The unmanned vehicle path control device  1001  is the apparatus for controlling the path of the unmanned vehicle according to any one of the embodiments of  FIGS. 8 and 9 . 
     The unmanned vehicle  1002  is configured to provide landmark information on a current location to the unmanned vehicle path control device  1001 , so that the unmanned vehicle path control device  1001  plans a path of the unmanned vehicle  1002  from the current location to the target location. After receiving the planned path transmitted by the unmanned vehicle path control device  1001 , the unmanned vehicle  1002  travels to the target position according to the planned path. 
     In some embodiments, the unmanned vehicle  1002  is further configured to identify landmark information set on a road during moving to the target location according to the planned path, and compare the identified landmark information with the planned path. If the recognized landmark information does not coincide with the planned path, the unmanned vehicle  1002  transmits the landmark information on the current position to the unmanned vehicle path control device  1001 , so that the unmanned vehicle path control device  1001  replans the path from the current position to the target position of the unmanned vehicle  1002 . 
     In some embodiments, the functional unit modules described above can be implemented as a general purpose Processor, a Programmable Logic Controller (PLC), a Digital Signal Processor (Digital Signal Processor, DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable Logic device, discrete Gate or transistor Logic, discrete hardware components, or any suitable combination thereof for performing the functions described in this disclosure. 
     It will be understood by those skilled in the art that all or part of the steps for implementing the above embodiments may be implemented by hardware, or may be implemented by a program instructing relevant hardware, where the program may be stored in a computer-readable storage medium, and the storage medium may be a read-only memory, a magnetic disk or an optical disk. 
     The description of the present disclosure has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the disclosure in the form disclosed. Many modifications and variations will be apparent to practitioners skilled in this art. The embodiment was chosen and described in order to best explain the principles of the disclosure and the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated.