Laser map updating method, robot and cluster robot system

Abstract

This application discloses a laser map update method, robot, and swarm robot system. The method includes: determining a point cloud to be updated based on the splicing results of a laser point cloud and a map laser point cloud, then updating the information of the point cloud to be updated to the laser map. If the difference between the updated laser map and the original map exceeds a preset first threshold, the update is abandoned; otherwise, the update is retained. This better ensures that the updated map is not rotated, translated, or scaled compared to the map before the update, laying the foundation for the normal operation of the upper-level business logic.

Description

Technical Field

[0001] The present application relates to the field of mobile robot map update technology, and in particular to a laser map update method, a robot, and a cluster robot system. Background Art

[0002] Existing laser navigation solutions all rely on maps and their immutability. In practice, they require a certain degree of robustness to environmental changes, particularly the structural environment upon which laser sensors rely. However, this robustness can be easily compromised in practice. The solution, therefore, is to update the map to maintain the robustness of the algorithm and thus ensure navigation accuracy.

[0003] However, existing map update solutions cannot guarantee that the updated map will not be rotated, translated, or scaled compared to the map before the update, which is the basis for ensuring the normal operation of the upper-level business logic.

[0004] Application Contents

[0005] Therefore, it is necessary to provide a laser map updating method, a robot and a cluster robot system to solve the technical problem that the updated map does not have rotation, translation and scaling compared with the map before the update.

[0006] To achieve the above objectives, the present application proposes a laser map updating method, which includes:

[0007] Splicing the laser point cloud with the map laser point cloud, and determining the point cloud to be updated based on the splicing result; the map laser point cloud is a combination of multiple point clouds that have a specific relationship with the laser point cloud;

[0008] According to the laser point cloud and the map laser point cloud, the information of the point cloud to be updated is updated to the laser map to obtain an updated laser map;

[0009] The updated laser map is compared with the original map. If the difference between the two maps exceeds a preset first threshold, the updated laser map is discarded; otherwise, the updated laser map is retained.

[0010] In some embodiments, stitching the laser point cloud with the map laser point cloud and determining the point cloud to be updated based on the stitching result specifically includes:

[0011] When the current laser point cloud and the map laser point cloud are successfully spliced, the current laser point cloud is spliced ​​with each point cloud in the map laser point cloud, and the successfully spliced ​​current laser point cloud is determined as the point cloud to be updated.

[0012] In some embodiments, stitching the laser point cloud with the map laser point cloud and determining the point cloud to be updated based on the stitching result specifically includes:

[0013] When the current laser point cloud and the map laser point cloud are successfully spliced, the current laser point cloud is spliced ​​with each point cloud in the map laser point cloud, and the successfully spliced ​​current laser point cloud is determined as the first point cloud to be updated;

[0014] When the current laser point cloud and the map laser point cloud are not successfully spliced, the current laser point cloud that fails to be spliced ​​is defined as a key point cloud, and the key point cloud is determined as a second point cloud to be updated, wherein the point cloud to be updated is a collection of the first point cloud to be updated and the second point cloud to be updated.

[0015] In some embodiments, updating the information of the point cloud to be updated to the laser map based on the laser point cloud and the map laser point cloud to obtain an updated laser map specifically includes:

[0016] Projecting the laser point cloud onto the pose of each point cloud in the map laser point cloud to generate a current projected point cloud;

[0017] Discretize the angle of each point cloud in the current projected point cloud and the map laser point cloud:

[0018] Traverse the current projected point cloud to determine whether it is a dynamic object and whether it is an obstacle / map change. If neither is the case, replace the corresponding point cloud on the map to be updated with the laser point cloud.

[0019] In some embodiments, traversing the current projected point cloud, determining whether it is a dynamic object and determining whether it is an obstacle / map change, and if neither is true, replacing the corresponding point cloud on the map to be updated with the laser point cloud, specifically includes:

[0020] Determine whether a first distance from any map laser point among all map laser points in the map laser point cloud to its emitting laser is greater than a second distance from the current laser point corresponding to the map laser point among all current laser points in the current laser point cloud to its emitting laser; if so, continue to determine whether the distance difference between the first distance and the second distance is greater than a second threshold; if so, determine that the current laser point cloud corresponds to a dynamic object, and do not update the map; if the distance difference is less than the second threshold, determine that the current laser point cloud does not correspond to the dynamic object, and replace the corresponding point cloud on the map to be updated with the current laser point cloud;

[0021] When it is determined that the first distance is less than the second distance, it is determined that the current laser point cloud corresponds to the obstacle / map change, and the current laser point cloud is used to replace the corresponding point cloud on the map to be updated.

[0022] In some embodiments, the method further comprises:

[0023] receiving at least one of the updated laser maps;

[0024] The at least one updated laser map is updated into the original map of the aircraft in chronological order.

[0025] To achieve the above objectives, the present application also proposes a robot, which includes a laser for acquiring the laser point cloud, and is used to execute the above laser map updating method.

[0026] To achieve the above objectives, the present application also proposes a robot, a cluster robot system, including multiple robots as described above.

[0027] In some embodiments, one of the robots in the system receives the updated laser map sent by other robots, updates multiple point cloud maps into the local original map in chronological order; and sends the updated map to other robots.

[0028] In some embodiments, the system further includes a central server, which is used to receive the updated laser map sent by one or more robots, and the central server updates one or more of the updated laser maps into the original map in time order, and sends the updated map to multiple robots.

[0029] The laser map updating method, robot and cluster robot system provided in the embodiments of the present application determine the point cloud to be updated based on the splicing results of the laser point cloud and the map laser point cloud, and then update the information of the point cloud to be updated to the laser map. If the difference between the updated laser map and the original map exceeds a preset first threshold, the update is abandoned; otherwise, the update is retained, thereby better ensuring that the updated map and the map before the update are not rotated, translated and scaled, laying the foundation for the normal operation of the upper-level business logic. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0031] Figure 1 This is a flowchart of a laser map updating method according to an embodiment of the present application;

[0032] Figure 2is a flowchart of a laser map updating method according to another embodiment of the present application;

[0033] Figure 3 is a flowchart of a laser map updating method according to another embodiment of the present application;

[0034] Figure 4 This is a structural block diagram of a robot according to an embodiment of the present application;

[0035] Figure 5 This is a structural block diagram of a cluster robot system according to an embodiment of the present application;

[0036] Figure 6 This is a structural block diagram of a cluster robot system according to another embodiment of the present application. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0038] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0039] In addition, the descriptions of "first", "second", etc. in this application are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0040] In this application, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] There is a laser on the robot. During the movement of the robot, the laser emits laser light, and the robot receives the reflection of objects, thereby sensing external objects.

[0042] In this application, a laser point cloud or simply point cloud is a collection of laser points captured by a robot at a location, and a laser point cloud map is a collection of such laser point clouds.

[0043] like Figure 1 As shown, the laser map updating method proposed in the embodiment of the present application includes:

[0044] Step 10: stitching the laser point cloud with the map laser point cloud, and determining the point cloud to be updated based on the stitching result; the map laser point cloud is a combination of multiple point clouds that have a specific relationship with the laser point cloud;

[0045] The laser point cloud can be the one currently being collected by the robot in real time, or it can be a collection of multiple laser point clouds collected at preset intervals during the robot's motion. The laser point cloud collected in real time is referred to as the current laser point cloud. Each laser point cloud is then stitched with the map laser point cloud.

[0046] A plurality of point clouds having a specific relationship with the laser point cloud, where the specific relationship can be selected according to the distance between each map point cloud and the laser point cloud, or in other ways.

[0047] Step 20: updating the information of the point cloud to be updated to the laser map based on the laser point cloud and the map laser point cloud to obtain an updated laser map;

[0048] Step 30: Compare the updated laser map with the original map. If the difference between the two maps exceeds a preset first threshold, the updated laser map is discarded; otherwise, the updated laser map is retained.

[0049] Specifically, the comparison algorithm is any image matching algorithm. The difference between the two maps exceeds a preset first threshold, specifically when the difference (in pixels) between the two maps is less than the first threshold. Typically, the first threshold ranges from 5% to 20% of the map size.

[0050] By comparing the updated laser map with the original map, if the updated laser map changes the map skeleton of the original map, the update is abandoned, thereby avoiding positioning deviations and preventing map update errors.

[0051] The laser map updating method provided in the embodiment of the present application determines the point cloud to be updated based on the splicing results of the current laser point cloud and the map laser point cloud, and then updates the information of the point cloud to be updated to the laser map. If the difference between the updated laser map and the original map exceeds a preset first threshold, the update is abandoned; otherwise, the update is retained, which better ensures that the updated map does not have rotation, translation, and scaling compared to the map before the update, laying the foundation for the normal operation of the upper-level business logic.

[0052] In some embodiments, the first strategy is used to determine the point cloud to be updated and the relative position between the current point cloud and the point cloud to be updated. The current laser point cloud and the map laser point cloud are spliced ​​together, and the point cloud to be updated is determined based on the splicing result, specifically including:

[0053] When the current laser point cloud and the map laser point cloud are successfully spliced, the current laser point cloud is spliced ​​with each point cloud in the map laser point cloud, and the successfully spliced ​​current laser point cloud is determined as the point cloud to be updated.

[0054] The current laser point cloud is stitched with the map laser point cloud. Each successful stitching result is considered a successful stitching. A successful stitching result is defined as the diagonal value of the covariance matrix of the stitched point cloud between the current laser point cloud and the corresponding point cloud in the map laser point cloud being less than a third threshold. The third threshold range is: 1e-6 to 1e-2.

[0055] In the embodiment of the present application, only the current laser point cloud that has been successfully spliced ​​is processed, and it is determined as the point cloud to be updated, and the map is updated in subsequent steps.

[0056] The specific method of using the current laser point cloud to update the map laser point cloud is as follows: current )’s pose (P current ) around a set of map point clouds ( by To express, the pose corresponding to each point cloud is by To express it), the selection method can be based on the position of each map point cloud from the current laser point (i.e. ) or other methods. Then use these map point clouds Combined generation of map laser point cloud (S merged ), S merged Pose P merged ) can be selected as The posture of It can also be other point cloud poses, but here we choose Then use S current With S merged The pose change between the two point clouds is obtained by stitching, that is,

[0057] When S current and S merged When the splicing is successful, use S current And each component S merged Point cloud Splice again, if the splicing is successful, you can get it directly If the splicing fails, It needs to be derived as follows:

[0058]

[0059] because So there is

[0060]

[0061] In another embodiment, the second strategy is used to determine the point cloud to be updated and the relative position between the current point cloud and the point cloud to be updated. The current laser point cloud and the map laser point cloud are spliced ​​together, and the point cloud to be updated is determined based on the splicing result, specifically including:

[0062] When the current laser point cloud and the map laser point cloud are successfully spliced, the current laser point cloud is determined as the first point cloud to be updated;

[0063] When the current laser point cloud and the map laser point cloud fail to be spliced, the failed current laser point cloud is determined as a key point cloud, the key point cloud is determined as the second point cloud to be updated, and the set of the first point cloud to be updated and the second point cloud to be updated is determined as the point cloud to be updated.

[0064] The first strategy simply updates the map laser point cloud only for the successful point clouds after the current laser point cloud and the map laser point cloud are successfully spliced ​​together, while the second strategy not only updates these successful point clouds, but also updates those unsuccessful point clouds (key point clouds) through the successful point clouds. For the sake of clarity, we define a successfully spliced ​​current point cloud as S current , pose P current , in this S current The current point cloud after the previous successful stitching, i.e. the key point cloud, is represented as Universal To express them, their corresponding poses are Universal Generally speaking, we set a maximum number of failures, n < the fourth threshold, and the fourth threshold is adjusted according to the actual situation, and the general range is 0-20. If the stitching is not successful, the increment between the key point cloud and the map laser point cloud corresponding to the key point cloud is S current This is derived from the stitching of the map, which means that the difference in angle and distance from the map laser point cloud meets the fifth threshold. The fifth threshold consists of two parts: angle between + / - 90 degrees and distance between 0 and 5 meters.

[0065] The derivation process of key point cloud to update map laser point cloud is as follows: Assume S current If the map is successfully connected, (See the first strategy for details.) For each failed splicing before this successful splicing First select the corresponding map laser point cloud (using the fifth threshold), by For universal expressions and their poses For these point clouds, each sum is derived The corresponding relative pose is

[0066]

[0067] In the second strategy, the key point cloud Failure of stitching does not mean giving up, but the map still needs to be updated because it is very likely that the environment has changed, resulting in unsuccessful stitching of the current laser point cloud with the point cloud in the map laser point cloud. This situation is very normal and is a very important part that needs to be updated in the embodiment of this application.

[0068] Furthermore, if Figure 2 As shown, the updating of the information of the point cloud to be updated to the laser map according to the laser point cloud and the map laser point cloud to obtain the updated laser map specifically includes:

[0069] Step 21: Project the current laser point cloud onto the pose of each point cloud in the map laser point cloud to generate a current projected point cloud;

[0070] Step 22: discretize the angle of each laser point in the current projected point cloud and the map laser point cloud;

[0071] Step 23: traverse the current projected point cloud to determine whether it is a dynamic object and whether it is an obstacle / map change. If neither is a dynamic object, replace the corresponding point cloud on the map to be updated with the laser point cloud.

[0072] When it is determined that the object is not a dynamic object and is not determined to be an obstacle / map change, the corresponding point cloud on the map to be updated is replaced by the laser point cloud.

[0073] Furthermore, the traversing of the current projected point cloud, determining whether it is a dynamic object and determining whether it is an obstacle / map change, and if neither is a dynamic object, replacing the corresponding point cloud on the map to be updated with the laser point cloud, specifically includes:

[0074] Determine whether a first distance from any map laser point among all map laser points in the map laser point cloud to its emitting laser is greater than a second distance from the current laser point corresponding to the map laser point among all current laser points in the current laser point cloud to its emitting laser; if so, continue to determine whether the distance difference between the first distance and the second distance is greater than a second threshold (the range of the second threshold is adjusted according to actual conditions, generally 5cm-30cm); if so, determine that the current laser point cloud corresponds to a dynamic object, and do not update the map; if the distance difference is less than the second threshold, determine that the current laser point cloud does not correspond to the dynamic object, and use the current laser point cloud to replace the corresponding point cloud on the map to be updated;

[0075] When it is determined that the first distance is less than the second distance, it is determined that the current laser point cloud corresponds to the obstacle / map change, and the current laser point cloud is used to replace the corresponding point cloud on the map to be updated.

[0076] Specifically, in this embodiment, the strategy adopted is: all laser points of the current laser point cloud are updated in the following way. As mentioned above, a laser point cloud is a collection of laser points captured by the robot at a position. First, use S current Projection to S map Under the pose of current ), then for S′ current and S map The angle of each point is discretized and then updated as described in the figure below.

[0077] Traverse S′ current Each laser point in Figure 3 In the figure, the origin O is defined as the location of the laser, the curve AB represents the map laser point under the map laser point cloud; the curve CD represents the current laser point under the current laser point cloud; Figure 3 In the left half of , the first distance from any map laser point of all map laser points in the map laser point cloud to its emitting laser, for example Figure 3The OA and OB segments in the definition curve AB represent the first distance rr. There are X map laser points on the definition curve AB. The distance from any map laser point to the origin O is the first distance. The second distance from the current laser point corresponding to the map laser point to the laser it emits among all the current laser points in the current laser point cloud is, for example, Figure 3 The OD line segment in the middle represents the second distance. In the right half, there are Y current laser points on the right side of the curve CD after point P. The distance from any current laser point to the origin O is the second distance rc.

[0078] Taking point P as the boundary, in the left half, the first distance is greater than the second distance; in the right half, the first distance is less than the second distance; point P is considered to have the first distance equal to the second distance, and this point does not need to be updated.

[0079] In the left half where the first distance is greater than the second distance, the new point (current laser point) may be a dynamic object. In this case, the second threshold T is used to make the judgment. Figure 3 Continuing to determine whether the distance difference between the first distance and the second distance is greater than a second threshold, if so, it is determined that the current laser point cloud corresponds to a dynamic object, and the map is not updated. If the distance difference is less than the second threshold, it is determined that the current laser point cloud does not correspond to the dynamic object, and the current laser point cloud is used to replace the corresponding point cloud on the map to be updated.

[0080] If the first distance is less than the right half of the second distance, the current laser point cloud is determined to correspond to the obstacle / map change, and the current laser point cloud replaces the corresponding point cloud on the map to be updated. If the first distance is less than the second distance, it indicates that the obstacle was previously moving or the map has changed. In this case, the update does not consider the second threshold T, that is, the current laser point cloud directly replaces the corresponding point cloud on the map to be updated.

[0081] Therefore, the laser map updating method of the embodiment of the present application can handle dynamic objects.

[0082] The above embodiment can be a single-machine (single-robot) map update solution, a laser map update method executed on a single machine, without involving interaction with other robots (except for map sharing and distribution). Of course, the embodiment of the present application can also be used in a multi-machine update solution, that is, multiple robots jointly update a laser map.

[0083] like Figure 4 As shown, when the subject executing the laser map updating method is a plurality of robots, the method further includes:

[0084] Step 40: receiving at least one updated laser map;

[0085] Step 50: Update the at least one updated laser map into the original map of the local machine in chronological order.

[0086] Steps 40 and 50 may be performed on a robot or on a central server.

[0087] At regular intervals (determined by the speed of map changes, such as half a day, daily, two days, three days, half a week, four days, or weekly), each robot sends its updated portion to the central server (or a specific robot). The central server (or a specific robot) receives the updated laser map from one or more robots and constructs one or more locally updated maps. Each locally updated map sent by each robot carries a number and is received by the central server (or a specific robot).

[0088] The center (or a robot) will do the following: for each local update received, add it to the original map in chronological order, and then execute steps 20 and 30 described in the single-machine strategy.

[0089] Finally, the fused map is sent to each robot. Multiple robots can collaboratively update the map. Each robot calculates the difference between its path and the original map. All robots then send this difference to a central processing location (either a server or a specific robot). The central server runs a fusion algorithm to integrate the collected information and then distributes the updated map to each robot, completing the map update process.

[0090] like Figure 5 As shown, an embodiment of the present application further provides a robot 100, wherein the robot 100 includes a laser 101 for acquiring the laser point cloud, and the robot 100 is used to execute the above-mentioned laser map updating method.

[0091] An embodiment of the present application also provides a cluster robot system 200, comprising a plurality of robots 100 as described above.

[0092] Optionally, one of the robots in the system receives the updated laser maps sent by other robots, updates multiple updated laser maps into a local original map in chronological order; and sends the updated map to other robots.

[0093] Furthermore, the system also includes a central server 201, which is used to receive the updated laser map sent by one or more robots. The central server updates the one or more updated laser maps into the original map in time order, and sends the updated fused map to multiple robots.

[0094] It should be noted that the robot and cluster robot system proposed in the embodiments of this application are based on the same inventive concept as the laser map update method proposed in the method embodiment of this application. The corresponding technical contents in the method embodiment, robot embodiment and cluster robot system embodiment are applicable to each other and will not be described in detail here.

[0095] The above are only preferred embodiments of the present application and do not limit the patent scope of the present application. All equivalent structural transformations made based on the contents of the present application specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present application.

Claims

1. A laser map updating method, characterized in that: The method comprises: Splicing the laser point cloud with the map laser point cloud, and determining the point cloud to be updated based on the splicing result; the map laser point cloud is a combination of multiple point clouds that have a specific relationship with the laser point cloud; According to the laser point cloud and the map laser point cloud, the information of the point cloud to be updated is updated to the laser map to obtain an updated laser map; Comparing the updated laser map with the original map, and if the difference between the two maps exceeds a preset first threshold, discarding the updated laser map; otherwise, retaining the updated laser map; The updating of the information of the point cloud to be updated to the laser map according to the laser point cloud and the map laser point cloud to obtain an updated laser map specifically includes: Projecting the laser point cloud onto the pose of each point cloud in the map laser point cloud to generate a current projected point cloud; Discretizing the angle of each point cloud in the current projected point cloud and the map laser point cloud; Traverse the current projected point cloud to determine whether it is a dynamic object and whether it is an obstacle / map change. If neither is the case, use the laser point cloud to replace the corresponding point cloud on the map to be updated.

2. The method according to claim 1, characterized in that The laser point cloud and the map laser point cloud are stitched together, and the point cloud to be updated is determined according to the stitching result, specifically including: When the current laser point cloud and the map laser point cloud are successfully spliced, the current laser point cloud is spliced ​​with each point cloud in the map laser point cloud, and the successfully spliced ​​current laser point cloud is determined as the point cloud to be updated.

3. The method according to claim 1, characterized in that The laser point cloud and the map laser point cloud are stitched together, and the point cloud to be updated is determined according to the stitching result, specifically including: When the current laser point cloud and the map laser point cloud are successfully spliced, the current laser point cloud is spliced ​​with each point cloud in the map laser point cloud, and the successfully spliced ​​current laser point cloud is determined as the first point cloud to be updated; When the current laser point cloud and the map laser point cloud are not successfully spliced, the current laser point cloud that fails to be spliced ​​is defined as a key point cloud, and the key point cloud is determined as a second point cloud to be updated, wherein the point cloud to be updated is a collection of the first point cloud to be updated and the second point cloud to be updated.

4. The method according to claim 1, wherein The traversing of the current projected point cloud, determining whether it is a dynamic object and determining whether it is an obstacle / map change, and if neither is the case, replacing the corresponding point cloud on the map to be updated with the laser point cloud, specifically includes: Determine whether a first distance from any map laser point among all map laser points in the map laser point cloud to its emitting laser is greater than a second distance from a current laser point corresponding to the map laser point among all current laser points in the current laser point cloud to its emitting laser; if so, continue to determine whether the distance difference between the first distance and the second distance is greater than a second threshold; if so, determine that the current laser point cloud corresponds to a dynamic object, and do not update the map; if the distance difference is less than the second threshold, determine that the current laser point cloud does not correspond to the dynamic object, and replace the corresponding point cloud on the map to be updated with the current laser point cloud; When it is determined that the first distance is less than the second distance, it is determined that the current laser point cloud corresponds to the obstacle / map change, and the current laser point cloud is used to replace the corresponding point cloud on the map to be updated.

5. The method according to any one of claims 1 to 4, characterized in that The method further comprises: receiving at least one updated laser map; The at least one updated laser map is updated into the original map of the aircraft in chronological order.

6. A robot, characterized in that: The robot includes a laser for acquiring the laser point cloud, and the robot is used to execute the laser map updating method according to any one of claims 1 to 5.

7. A cluster robot system, characterized in that: The method comprises a plurality of robots as claimed in claim 6.

8. The cluster robot system according to claim 7, characterized in that: One of the robots in the system receives the updated laser maps sent by other robots, and updates the multiple laser maps into a local original map in chronological order; And send the updated map to other robots.

9. The cluster robot system according to claim 7, characterized in that: The system also includes a central server, which is used to receive the updated laser map sent by one or more robots. The central server updates the one or more updated laser maps into the original map in time order and sends the updated map to multiple robots.

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