Mobile robot double-vehicle linkage positioning method

Abstract

The invention relates to the technical field of positioning of mobile robots, in particular to a mobile robot double-vehicle linkage positioning method, which comprises the following steps: step 1) after a scheduling system sends a linkage task, a master-slave relationship is allocated to two mobile robots about to execute the linkage task; 2) positioning in the natural contour map through laser point cloud data scanned on the main vehicle, and obtaining the absolute position of the main vehicle in the contour map; 3) acquiring laser point cloud data of the slave vehicle, and matching the laser point cloud data of the slave vehicle with the laser point cloud data of the master vehicle to obtain a relative position between the two vehicles; (4) whether the relative positions are correct or not is verified through the reflectors on the master vehicle and the slave vehicle; and step 5) through a verification result, carrying out coordinate conversion to obtain an absolute position of the slave vehicle. According to the invention, the positioning accuracy of double-vehicle linkage can be improved. A double-vehicle relative positioning concept is adopted as a whole, and error superposition caused by absolute positioning of double vehicles is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of mobile robot positioning, in particular to a dual-vehicle linkage positioning method for mobile robots. Background Art

[0002] With the continuous development of industrial automation, the demand for mobile robots to transport large goods is also increasing. Although heavy-duty mobile robots can carry large goods, they often need to be designed according to demand, and their functions are relatively simple and difficult to operate. Therefore, the demand for dual mobile robots to carry goods in a coordinated manner is particularly prominent.

[0003] The linkage of two mobile robots requires high positioning accuracy. When carrying the same cargo, the two robots need to be synchronized at the same frequency. At present, the linkage mobile robots basically use magnetic strips or ribbons for positioning. Although this positioning method has high accuracy, it is difficult to deploy and the running route cannot be easily changed; the natural contour positioning method generally divides the robots into a master-slave relationship, relying only on the positioning result of one of the robots, and then using optical communication to realize the scheduling of the two robots. However, this method is limited by the optical communication effect. If the two robots are positioned and scheduled separately, the positioning accuracy is often not guaranteed. When the positioning errors of the two vehicles are superimposed, the linkage relationship will be destroyed. Summary of the invention

[0004] The purpose of the present invention is to provide a mobile robot dual-vehicle linkage positioning method to overcome the situation that the positioning accuracy of the dual-vehicle linkage cannot meet the requirements of the natural contour positioning method.

[0005] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: a mobile robot dual-vehicle linkage positioning method, comprising the following steps:

[0006] Step 1) When the scheduling system issues a linkage task, a master-slave relationship is assigned to the two mobile robots that are about to perform the linkage task;

[0007] Step 2) Positioning the main vehicle in the natural contour map using the laser point cloud data scanned on the main vehicle to obtain the absolute position of the main vehicle in the contour map;

[0008] Step 3) Obtain the laser point cloud data of the slave vehicle and match it with the laser point cloud data of the master vehicle to obtain the relative position between the two vehicles;

[0009] Step 4) Verify the relative positions of the master and slave vehicles by using reflective objects on the master and slave vehicles to see if they are correct;

[0010] Step 5) By verifying the result, coordinate transformation is performed to obtain the absolute position of the slave vehicle.

[0011] Before executing step 1), a master-slave relationship is assigned to the two linked mobile robots, specifically:

[0012] Among them, the main vehicle uses 2D laser point cloud to locate in the natural contour map that has been built, so as to determine the absolute positioning result in the main vehicle contour map;

[0013] Then use the 2D laser point cloud of the slave vehicle and the 2D laser point cloud of the master vehicle for relative positioning; and add calibration reflective objects on the bodies of the master vehicle and the slave vehicle to further verify whether the relative position is accurate;

[0014] After verification, the absolute positioning result of the master vehicle and the relative positioning result between the two vehicles are converted to obtain the absolute position of the slave vehicle in the contour map.

[0015] The step 1) is specifically:

[0016] 1-1) In the dual-vehicle linkage, the center of the cargo is set as the center of the vehicle body when the master vehicle and the slave vehicle are linked according to the cargo situation;

[0017] 1-2) Calculate the position relationship of each vehicle relative to the center of the vehicle body in the linkage mode, where the center coordinate system of the vehicle body is represented by P o To represent, the conversion relationship is represented by T, then the corresponding coordinate P of the car c It can be expressed as:

[0018] P c =P o ·T

[0019] 1-3) Synchronize the driving information of the two vehicles’ system time, running speed, acceleration, and rotation angular velocity.

[0020] The step 2) is specifically:

[0021] 2-1) Before positioning, a natural contour map must be constructed first, and the collected 2D laser point cloud data must be sampled into features to form a feature map;

[0022] 2-2) During positioning, the current position of the robot in the natural environment can be determined by matching the laser point cloud data of the current frame with the feature map.

[0023] The step 3) is specifically:

[0024] 3-1) retaining the laser point cloud of the main vehicle located by natural contour in step 2), and adding the body model of the main vehicle to the laser point cloud in the form of point cloud information, thereby forming the target point cloud;

[0025] 3-2) Obtain the laser point cloud of the slave vehicle at the same time as the laser point cloud of the master vehicle positioning to form a matching source point cloud;

[0026] 3-3) Perform ICP point cloud matching on the source point cloud and the target point cloud to obtain the relative position of the slave vehicle to the master vehicle. The point cloud registration problem is described as:

[0027]

[0028] Among them, P s and P t It is the corresponding point in the laser point cloud of the master vehicle and the laser point cloud of the slave vehicle. The minimum distance difference between the laser point cloud of the slave vehicle and the corresponding point is calculated after the RT change.

[0029] The step 4) is specifically:

[0030] 4-1) According to the linkage form, the laser point clouds of the two vehicles are scanned on each other's body; the highlight points are extracted from the source point cloud and the target point cloud in step 3), and if the width of the highlight point is consistent with the width of the reflective object, it is extracted as a landmark point;

[0031] 4-2) When the slave vehicle verifies its relative relationship with the master vehicle or the master vehicle verifies its relative relationship with the slave vehicle, multiple marker point information is extracted from the source point cloud, and the marker points are selected according to the actual reflective object spacing, and two marker points that meet the actual reflective object spacing are selected to form a point pair;

[0032] 4-3) Describe the two marker points in the polar coordinate system of the laser head of the vehicle, and then calculate the relative relationship including angle and position. Use this relative position to verify the relative position of the point cloud matching solution in step 3);

[0033] The conversion relationship between the polar coordinate system and the rectangular coordinate system is calculated by the following formula, namely:

[0034] X=r·cosθ

[0035] Y=r·sinθ

[0036] Among them, X and Y are the coordinate values ​​of the rectangular coordinate system, and r and θ are two coordinates in the polar coordinate system.

[0037] The step 5) is specifically:

[0038] According to the robot coordinate system conversion principle, the absolute position of the master vehicle in the natural contour map in step 2) is multiplied by the relative position after verification in step 4) to calculate the absolute position of the slave vehicle in the natural contour map, thereby completing the linkage positioning between the two vehicles.

[0039] The present invention has the following beneficial effects and advantages:

[0040] 1. The present invention can improve the positioning accuracy of the dual-vehicle linkage. The overall concept of relative positioning of the dual-vehicles is adopted, which avoids the error superposition caused by absolute positioning of both vehicles.

[0041] 2. The present invention also adds a method of using reflective objects to verify the relative relationship, which further prevents the situation of no solution or wrong solution, increases the robustness of the relative relationship between the two vehicles, and thus ensures the operation effect of the two-vehicle linkage. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is the overall flow chart of the present invention. DETAILED DESCRIPTION

[0043] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0044] like Figure 1 As shown in the figure, it is an overall flow chart of the present invention. The present invention provides a mobile robot dual-vehicle linkage positioning method, comprising the following steps:

[0045] Step 1: When the scheduling system issues a linkage task, it assigns a master-slave relationship to the two mobile robots that are about to perform the linkage task. Specifically:

[0046] Before executing step 1, the two linked mobile robots are assigned a master-slave relationship, wherein the master vehicle uses a 2D laser point cloud to locate itself in a natural contour map that has been built, thereby determining the absolute positioning result in the contour map of the master vehicle. The 2D laser point cloud of the slave vehicle is then used to perform relative positioning with the 2D laser point cloud of the master vehicle. Verification reflectors are added to the bodies of the master and slave vehicles to further verify whether the relative position is accurate. After verification, the absolute positioning result of the master vehicle and the relative positioning result between the two vehicles are converted to obtain the absolute position of the slave vehicle in the contour map.

[0047] The specific contents of assigning the master-slave relationship to the two mobile robots include:

[0048] One is the master vehicle and the other is the slave vehicle. The center of the cargo is set as the center of the vehicle body when the two vehicles are linked according to the cargo situation. The position relationship of each vehicle relative to the center of the vehicle body in the linkage mode is calculated. The system time, running speed, acceleration, rotation angular velocity and other information of the two vehicles are synchronized.

[0049] 1-1) In the dual-vehicle linkage, the center of the cargo is set as the center of the vehicle body when the master vehicle and the slave vehicle are linked according to the cargo situation;

[0050] 1-2) Calculate the position relationship of each vehicle relative to the center of the vehicle body in the linkage mode, where the center coordinate system of the vehicle body is represented by P o To represent, the conversion relationship is represented by T, then the corresponding coordinate P of the car cIt can be expressed as:

[0051] P c =P o ·T

[0052] 1-3) Synchronize the driving information of the two vehicles’ system time, running speed, acceleration, and rotation angular velocity.

[0053] Step 2: Use the laser point cloud data of the main vehicle to locate in the natural contour map and obtain the absolute position of the main vehicle in the contour map. Specifically:

[0054] Before positioning, a natural contour map must be constructed first, and the 2D laser point cloud data collected during the map construction is sampled as features to form a feature map. During positioning, the laser point cloud data of the current frame is matched with the feature map to determine the current position of the robot in the natural environment.

[0055] Step 3: Get the laser point cloud data of the slave vehicle and match it with the laser point cloud data of the master vehicle to get the relative position between the two vehicles. Specifically:

[0056] The step 3) is specifically:

[0057] 3-1) retaining the laser point cloud of the main vehicle located by natural contour in step 2), and adding the body model of the main vehicle to the laser point cloud in the form of point cloud information, thereby forming the target point cloud;

[0058] 3-2) Obtain the laser point cloud of the slave vehicle at the same time as the laser point cloud of the master vehicle positioning to form a matching source point cloud;

[0059] 3-3) Perform ICP point cloud matching on the source point cloud and the target point cloud to obtain the relative position of the slave vehicle to the master vehicle. The point cloud registration problem is described as:

[0060]

[0061] Among them, P s and P t It is the corresponding point in the laser point cloud of the master vehicle and the laser point cloud of the slave vehicle. The minimum distance difference between the laser point cloud of the slave vehicle and the corresponding point is calculated after the RT change.

[0062] Step 4: Use the reflective objects on the master and slave vehicles to check whether their relative positions are correct. Specifically:

[0063] 4-1) According to the linkage form, the laser point clouds of the two vehicles are scanned on each other's body; the highlight points are extracted from the source point cloud and the target point cloud in step 3), and if the width of the highlight point is consistent with the width of the reflective object, it is extracted as a landmark point;

[0064] 4-2) When the slave vehicle verifies its relative relationship with the master vehicle or the master vehicle verifies its relative relationship with the slave vehicle, multiple marker point information is extracted from the source point cloud, and the marker points are selected according to the actual reflective object spacing, and two marker points that meet the actual reflective object spacing are selected to form a point pair;

[0065] 4-3) Describe the two marker points in the polar coordinate system of the laser head of the vehicle, and then calculate the relative relationship including angle and position. Use this relative position to verify the relative position of the point cloud matching solution in step 3);

[0066] The conversion relationship between the polar coordinate system and the rectangular coordinate system is calculated by the following formula:

[0067] X=r·cosθ

[0068] Y=r·sinθ

[0069] Among them, X and Y are the coordinate values ​​of the rectangular coordinate system, and r and θ are two coordinates in the polar coordinate system.

[0070] Step 5: Verify and convert the coordinates to get the absolute position of the slave vehicle. Specifically:

[0071] According to the robot coordinate system conversion principle, the absolute position of the master vehicle in the natural contour map in step 2 is multiplied by the relative position verified in step 4 to calculate the absolute position of the slave vehicle in the natural contour map, thereby completing the linkage positioning between the two vehicles.

[0072] In summary, the present invention adopts the concept of relative positioning of two vehicles, avoiding the error superposition caused by absolute positioning of both vehicles. At the same time, a method of using reflective objects to verify the relative relationship is added. This further prevents the situation of no solution or wrong solution, increases the robustness of the relative relationship between the two vehicles, and thus ensures the operation effect of the linkage of the two vehicles.

[0073] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A mobile robot dual-vehicle linkage positioning method, characterized in that: The following steps are involved: Step 1) When the scheduling system issues a linkage task, a master-slave relationship is assigned to the two mobile robots that are about to perform the linkage task; Step 2) Positioning the main vehicle in the natural contour map using the laser point cloud data scanned on the main vehicle to obtain the absolute position of the main vehicle in the contour map; Step 3) Obtain the laser point cloud data of the slave vehicle and match it with the laser point cloud data of the master vehicle to obtain the relative position between the two vehicles; Step 4) Verify the relative positions of the master and slave vehicles by using reflective objects on the master and slave vehicles to see if they are correct; Step 5) By verifying the result, coordinate transformation is performed to obtain the absolute position of the slave vehicle.

2. A mobile robot dual-vehicle linkage positioning method according to claim 1, characterized in that: Before executing step 1), a master-slave relationship is assigned to the two linked mobile robots, specifically: Among them, the main vehicle uses 2D laser point cloud to locate in the natural contour map that has been built, so as to determine the absolute positioning result in the main vehicle contour map; Then use the 2D laser point cloud of the slave vehicle and the 2D laser point cloud of the master vehicle for relative positioning; and add calibration reflective objects on the bodies of the master vehicle and the slave vehicle to further verify whether the relative position is accurate; After verification, the absolute positioning result of the master vehicle and the relative positioning result between the two vehicles are converted to obtain the absolute position of the slave vehicle in the contour map.

3. A mobile robot dual-vehicle linkage positioning method according to claim 1, characterized in that: The step 1) is specifically: 1-1) In the dual-vehicle linkage, the center of the cargo is set as the center of the vehicle body when the master vehicle and the slave vehicle are linked according to the cargo situation; 1-2) Calculate the position relationship of each vehicle relative to the center of the vehicle body in the linkage mode, where the center coordinate system of the vehicle body is represented by P o To represent, the conversion relationship is represented by T, then the corresponding coordinate P of the car c It can be expressed as: Pc=Po·T 1-3) Synchronize the driving information of the two vehicles’ system time, running speed, acceleration, and rotation angular velocity.

4. A mobile robot dual-vehicle linkage positioning method according to claim 1, characterized in that: The step 2) is specifically: 2-1) Before positioning, a natural contour map must be constructed first, and the collected 2D laser point cloud data must be sampled into features to form a feature map; 2-2) During positioning, the current position of the robot in the natural environment can be determined by matching the laser point cloud data of the current frame with the feature map.

5. The method for positioning a mobile robot using dual vehicles in linkage according to claim 1, characterized in that: The step 3) is specifically: 3-1) retaining the laser point cloud of the main vehicle located by natural contour in step 2), and adding the body model of the main vehicle to the laser point cloud in the form of point cloud information, thereby forming the target point cloud; 3-2) Obtain the laser point cloud of the slave vehicle at the same time as the laser point cloud of the master vehicle positioning to form a matching source point cloud; 3-3) Perform ICP point cloud matching on the source point cloud and the target point cloud to obtain the relative position of the slave vehicle to the master vehicle. The point cloud registration problem is described as: Among them, P s and P t It is the corresponding point in the laser point cloud of the master vehicle and the laser point cloud of the slave vehicle. The minimum distance difference between the laser point cloud of the slave vehicle and the corresponding point is calculated after the RT change.

6. A mobile robot dual-vehicle linkage positioning method according to claim 1, characterized in that: The step 4) is specifically: 4-1) According to the linkage form, the laser point clouds of the two vehicles are scanned on each other's body; the highlight points are extracted from the source point cloud and the target point cloud in step 3), and if the width of the highlight point is consistent with the width of the reflective object, it is extracted as a landmark point; 4-2) When the slave vehicle verifies its relative relationship with the master vehicle or the master vehicle verifies its relative relationship with the slave vehicle, multiple marker point information is extracted from the source point cloud, and the marker points are selected according to the actual reflective object spacing, and two marker points that meet the actual reflective object spacing are selected to form a point pair; 4-3) Describe the two markers in the polar coordinate system of the laser head of the vehicle, and then calculate the relative relationship including angle and position. Use this relative position to verify the relative position of the point cloud matching solution in step 3); the conversion relationship between the polar coordinate system and the rectangular coordinate system is calculated by the following formula, namely: Xrcos0 Yr·sinθ Among them, X and Y are the coordinate values ​​of the rectangular coordinate system, and r and θ are two coordinates in the polar coordinate system.

7. The method for positioning a mobile robot with two vehicles in linkage according to claim 1, characterized in that: The step 5) is specifically: According to the robot coordinate system conversion principle, the absolute position of the master vehicle in the natural contour map in step 2) is multiplied by the relative position after verification in step 4) to calculate the absolute position of the slave vehicle in the natural contour map, thereby completing the linkage positioning between the two vehicles.

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