Method for capturing multiple dynamic targets by multiple robots

Abstract

The invention discloses a method for multiple robots to surround multiple dynamic targets, and the method comprises the steps: sensing the position information of the multiple dynamic targets through sensors carried by the robots, and determining the center and radius of a minimum circle containing all the targets according to the position information; and inputting the position of the circle center into each robot controller, and controlling the robot to surround the circle center according to the collision avoidance distance. The method has the advantages that under the condition that the position information of the targets does not need to be known in advance and the formation of the multiple robots does not need to be preset in advance, the concept of the virtual circle center is utilized, and surrounding of the multiple targets is converted into surrounding of the multiple robots on a circle with an area. The method is good in convergence, and can well complete a task of hunting a plurality of targets.

Description

Technical Field

[0001] The invention relates to the technical field of robot target encirclement and capture, and is particularly applicable to a method for encircling multiple dynamic targets by multiple robots. Background Art

[0002] Robot system is an important branch of robotics research, and it has attracted the attention of a large number of scholars as early as the 1980s. Compared with a single robot, a multi-robot system has the advantages of small size, large number, strong flexibility, high robustness, and simple structure, and can perform some tasks that a single robot cannot perform. Generally speaking, a multi-robot system is equipped with more sensing devices, has a wider sensing range and a flexible and changeable topological structure, and can handle multiple tasks at the same time; in addition, the multi-robot system also has a certain degree of robustness. Therefore, when a robot fails due to some force majeure during the operation of the multi-robot system, the multi-robot system can coordinate internally and use other normal robots to temporarily replace the failed one to continue to complete the task. When performing some difficult tasks with constantly changing environments and high efficiency requirements, a multi-robot system can greatly improve the robustness and work efficiency of the entire system, and is a better choice.

[0003] The coordinated capture of targets is about how multiple robots can complete the capture of multiple targets while being able to sense the positions of all targets. At the same time, it is also necessary to consider the collision avoidance between robots and between robots and targets. It has important significance in life.

[0004] However, most current research only focuses on the capture of a single target by multiple robots. When the number of targets becomes multiple, additional restrictions are required, such as requirements on the initial formation shape of the robots, or failure to consider issues such as obstacle avoidance between robots. Summary of the invention

[0005] The present invention aims to provide a method for capturing multiple dynamic targets by multiple robots, which is used for capturing multiple dynamic targets in a two-dimensional plane map.

[0006] To achieve the above object, the present invention adopts the following technical solutions: The method for multi-robot encirclement and capture of multiple dynamic targets described in the present invention comprises the following steps: the multi-robots sense the position information of the multiple dynamic targets through the sensors carried by the multi-robots, determine the center and radius of the smallest circle containing all the targets according to the position information; input the center position of the circle into the controllers of each robot, and control the robots to encircle the center of the circle according to the collision avoidance distance.

[0007] Furthermore, the number n of robots is greater than or equal to 3 times the number m of dynamic targets.

[0008] Furthermore, the step of determining the center and radius of the smallest circle containing all the objects includes: S1, randomly select three non-collinear points from the point set consisting of the position information of all dynamic targets; S2, constructing a circle based on the three-point position information; S3, determining whether the position information of the dynamic targets is included in the construction circle one by one, until the position information of all the dynamic targets is included in the construction circle; S4, using the three-point position information to determine the center and radius of the constructed circle.

[0009] Furthermore, in step S3, if the position information of the current dynamic target is outside the construction circle, it is necessary to select three non-collinear points from the position information of the current dynamic target and the three-point position information selected for the current construction circle, and construct a second construction circle that includes both the position information of the current dynamic target and the three-point position information selected for the current construction circle, and then determine one by one whether the position information of the dynamic target is covered by the second construction circle until the second construction circle covers the position information of all dynamic targets.

[0010] Furthermore, the collision avoidance distance is slightly larger than the radius of the minimum circle.

[0011] The advantages of the present invention are that it does not need to know the position information of the target in advance, and it does not need to predetermine the multi-robot formation in advance. By using the concept of virtual center of circle, the capture of multiple targets is converted into the capture of a circle with an area by multiple robots. The present invention has good convergence and can well complete the task of capturing multiple targets. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The present invention is a flowchart of the steps of determining the center and radius of the smallest circle containing all objects in the method of the present invention.

[0013] Figure 2 The present invention is a specific implementation flow chart of the method. DETAILED DESCRIPTION

[0014] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] Example 1 In the method for multi-robot encirclement and capture of multiple dynamic targets described in the present invention, the multi-robots sense the position information of the multiple dynamic targets through the sensors they carry, and determine the center and radius of the smallest circle containing all the targets based on the position information; the center position is input into each robot controller, and the robots are controlled to encircle the center according to the collision avoidance distance.

[0016] The number of robots n is greater than or equal to 3 times the number of dynamic targets m, that is, n≥3m.

[0017] like Figure 1 As shown, the step of determining the center and radius of the smallest circle containing all the targets includes: S1, randomly select three non-collinear points from the point set consisting of the position information of all dynamic targets; if the three points are on a straight line, change other points.

[0018] S2, construct a circle based on the three-point position information.

[0019] S3, determining whether the position information of the dynamic targets is included in the construction circle one by one, until the position information of all the dynamic targets is included in the construction circle.

[0020] If the constructed circle covers the position information of all dynamic targets, the center and radius of the constructed circle are directly calculated.

[0021] If it is found during the judgment process that the position information of the current dynamic target is outside the construction circle, three points that are not collinear should be selected from the position information of the current dynamic target and the three points of the position information selected by the current construction circle, and a second construction circle containing both the position information of the current dynamic target and the three points of the position information selected by the current construction circle should be constructed, and then the position information of the dynamic targets should be judged one by one whether it is included in the second construction circle, until the second construction circle covers the position information of all dynamic targets.

[0022] S4, using the three-point position information to determine the center and radius of the constructed circle.

[0023] Finally, it should be emphasized that in order to prevent collisions between multiple robots and between robots and moving targets, a collision avoidance distance needs to be set. However, the collision avoidance distance should be slightly larger than the radius of the minimum circle, so that the encirclement formed covers the construction circle and the target is captured.

[0024] Example 2 Specific implementation steps of the multi-robot multi-target capture method of the present invention like Figure 2 As shown, the multi-robot capture multi-target method of the present invention is adopted: Step 1: Create a two-dimensional plane map. There are n robots and m targets in the map, and the positions of the robots and moving targets are randomly distributed in a certain area.

[0025] Neither the robot nor the moving target requires an initial formation. The random seed function in MATLAB can be used to generate the initial position information of the two in a certain area of ​​the two-dimensional plane map. At the same time, the number n of robots and the number m of targets satisfy the quantitative relationship.

[0026] Step 2: Set the kinematic equations of each moving target to control the motion trajectory of each moving target.

[0027] In this embodiment, the dynamic characteristics of each moving target are the same, and the kinematic equation is as follows: In the formula Indicates The position of a target at time t; Indicates The speed of a target at time t; Indicates The acceleration input of a target at time t; M is the number of targets.

[0028] Step three: Each robot senses the position information of each moving target through the sensors it carries.

[0029] Step 4: determine the smallest circle that includes all moving targets based on the position information of each moving target and obtain the center and radius of the circle.

[0030] According to the method steps for obtaining the minimum circle containing all moving targets in the multi-robot multi-target capture method of the present invention, it is assumed that the position information of the three points of the minimum circle obtained at time t is: The coordinates of the center of the circle are determined as follows: The radius of the circle is: Step 5: Input the center position of the circle into each robot controller, and control the robot to surround the center of the circle according to the collision avoidance distance, that is, the encirclement of multiple targets by multiple robots is transformed into the encirclement of a single target, i.e., the center of the circle, by multiple robots.

[0031] The kinematic equation of the robot is In the formula Indicates The position of a robot at time t; Indicates The speed of a robot at time t; Indicates The acceleration input of a robot at time t; N is the number of robots.

[0032] As the robots surround the center of the circle, the speed of the moving target is unknown, so a pair is needed Speed ​​Observer , considering that the control input of the multi-robot system is ,in The definition is as follows: In the formula, is a positive constant gain, P O is the determined center of the circle. i is the position of the ith robot , represents the position difference between the i-th robot and the j-th robot. for p ij Model.

[0033] is the collision avoidance threshold function, the formula is: in, is the collision avoidance threshold, that is, the shortest distance between robots that cannot be less than. Used to determine the agent's neighbors, that is, the distance less than For neighbors. Overall, The smaller, The larger it is, the greater the repulsion effect.

[0034] In addition, by setting the collision avoidance distance d, the collision avoidance distance is slightly larger than the radius of the circle. In this way, the encirclement formed by multiple robots around the center of the circle is slightly larger than the minimum circle containing all the targets mentioned above, which means that the task of capturing multiple targets is completed.

[0035] The neighbors of robot i are defined as the following set: , Used to determine the agent's neighbors, that is, the distance less than For neighbors.

Claims

1. A method for capturing multiple dynamic targets by multiple robots, characterized in that: The multiple robots sense the position information of multiple dynamic targets through the sensors they carry, and determine the center and radius of the smallest circle that includes all the targets based on the position information; the center position of the circle is input into each robot controller, and the robots are controlled to surround the center of the circle according to the collision avoidance distance.

2. The method for capturing multiple dynamic targets by multiple robots according to claim 1, characterized in that: The number n of robots is greater than or equal to 3 times the number m of dynamic targets.

3. The method for capturing multiple dynamic targets by multiple robots according to claim 1, characterized in that: The step of determining the center and radius of the smallest circle containing all the objects comprises: S1, randomly select three non-collinear points from the point set consisting of the position information of all dynamic targets; S2, constructing a circle based on the three-point position information; S3, determining whether the position information of the dynamic targets is included in the construction circle one by one, until the position information of all the dynamic targets is included in the construction circle; S4, using the three-point position information to determine the center and radius of the constructed circle.

4. The method for capturing multiple dynamic targets by multiple robots according to claim 3, characterized in that: In step S3, if the position information of the current dynamic target is outside the construction circle, it is necessary to select three non-collinear points from the position information of the current dynamic target and the three-point position information selected for the current construction circle, and construct a second construction circle that includes both the position information of the current dynamic target and the three-point position information selected for the current construction circle. Then, determine one by one whether the position information of the dynamic target is covered by the second construction circle until the second construction circle covers the position information of all dynamic targets.

5. The method for capturing multiple dynamic targets by multiple robots according to claim 1, characterized in that: The collision avoidance distance is slightly larger than the radius of the minimum circle.

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