Multi-robot flexible connection cooperative transportation system and its visual error positioning and navigation method

Abstract

The present invention discloses a multi-robot flexible connection cooperative transportation system and a visual error positioning and navigation method thereof, which belongs to the field of intelligent logistics transport robots. The cooperative transportation system includes a pilot robot with a pilot cooperation device and several follower robots with follower cooperation devices. Both the pilot cooperation device and the follower cooperation device can connect the mobile robot with the transported object, which allows large deviations during cooperative transportation and can actively reduce errors based on them. The visual error positioning and navigation method includes a cooperative device of the follower robot and other heterogeneous sensors, and the errors detected by the cooperative device of the follower robot are combined with information from other heterogeneous sensors to complete the formation maintenance control during cooperative transportation of multiple mobile robots.

Description

Technical Field

[0001] The present invention belongs to the field of intelligent logistics delivery robots, and specifically relates to a multi-robot flexible connection collaborative transportation system and a visual error positioning and navigation method thereof. Background Art

[0002] With the development of smart factories, the problems that need to be solved by robots are becoming more and more complex, and higher requirements are placed on the performance of robots. Complex and arduous tasks may require a single expensive and highly intelligent robot to complete, which brings a high economic burden, and even some tasks cannot be completed by a single robot. However, using multiple cheap and simple robots to cooperate to complete a complex and arduous task can save costs and improve work efficiency more than a single robot, so scholars have proposed a solution for multi-robot collaborative work. Multi-robot collaboration refers to multiple robots forming a group, which can overcome external interference while maintaining a complete formation during the movement, and reach the designated destination to complete the designated task. Usually, when transporting objects with irregular shapes or excessive weight, multiple robots can be used to transport them collaboratively in a limited space, which can effectively reduce transportation costs. Therefore, multi-robot collaborative transportation has become a hot topic of research at home and abroad, with broad application and development prospects.

[0003] The research focus of multi-robot cooperative transportation is on formation control. Domestic and foreign scholars have proposed theoretical methods such as pilot-follower method, virtual structure method, behavior-based method, and artificial potential field method to achieve formation control of cooperative transportation. Based on the above methods, the existing technology reports have conducted a lot of research on the cooperative control of multi-robots, but most of them are concentrated in the field of cooperative transportation of two robots. There are still few studies on the cooperative control of three or more robots, and the relevant technology is still imperfect. Summary of the invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a multi-robot flexible connection collaborative transportation system and its visual error positioning and navigation method, so as to solve the technical problems of multi-robot collaborative transportation of large objects, heavy objects and special-shaped objects.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention discloses a multi-robot flexible connection cooperative transportation system, comprising a pilot robot and a plurality of follower robots, a follower cooperative device is arranged on the top of each follower robot, a pilot cooperative device is arranged on the top of the pilot robot, and the pilot cooperative device and the plurality of follower cooperative devices cooperate to transport the transported object;

[0007] In the following cooperative device, an image acquisition device is provided for detecting and feeding back the relative displacement and relative rotation of the following robot.

[0008] Preferably, the following cooperative device is provided with a supporting top plate, a cooperative outer ring, a first lubricating sheet and a cooperative bottom plate in order from top to bottom; a cooperative supporting block and a second lubricating sheet are stacked in the cavity of the cooperative outer ring, and buffer pads for limiting and buffering are distributed on the inner wall of the cooperative outer ring, one end of the spring is fixed on the cooperative supporting block, and the other end is fixed on the inner wall of the cooperative outer ring between adjacent buffer pads; wherein:

[0009] The inner diameter of the first lubricating sheet is greater than that of the second lubricating sheet; a characteristic mark is provided at the bottom of the first lubricating sheet, and the first lubricating sheet and the cooperative bottom plate are provided with holes that penetrate each other. An image acquisition device is provided at the bottom of the cooperative bottom plate for acquiring the position information of the characteristic mark.

[0010] Preferably, the pilot coordination device is provided with a support top plate, a coordination outer ring, a first lubricating sheet and a coordination bottom plate in order from top to bottom; a coordination support block and a second lubricating sheet are stacked in the cavity of the coordination outer ring, and a buffer pad for limiting and buffering is distributed on the inner wall of the coordination outer ring; wherein:

[0011] The inner diameters of the first lubricating sheet and the second lubricating sheet are the same, and the inner diameter of the buffer pad is the same as the outer diameter of the second lubricating sheet.

[0012] Further preferably, the first lubricating sheet and the second lubricating sheet are brass graphite sheets.

[0013] Further preferably, a plurality of supporting cylinders connected to the robot are provided at the bottom of the cooperative base plate.

[0014] Further preferably, the supporting top plate includes a common supporting plate with holes, a foam supporting plate and a supporting plate with a V-shaped bracket.

[0015] Further preferably, the image acquisition device is a camera, a video camera or a camera.

[0016] Further preferably, the number of the follower robots is 2, 3 or more.

[0017] Further preferably, the following cooperative device and the pilot cooperative device are also provided with vehicle-mounted sensors, and there are three types of vehicle-mounted sensors, namely, a wheel encoder, a vehicle-mounted radar and an inertial navigation device; wherein:

[0018] Wheel encoder, used to detect the displacement and running speed of the robot;

[0019] Onboard radar, used to identify the geometric features of the operating environment and move the robot's global position and global posture;

[0020] The inertial navigation device is used to detect the linear acceleration, linear velocity, angular acceleration and angular velocity of the robot's motion.

[0021] The present invention also discloses a visual error navigation method based on the above-mentioned multi-robot flexible connection cooperative transportation system, comprising the following steps:

[0022] S1: Detect the relative displacement and relative rotation angle between each follower robot and the transported object through an image acquisition device;

[0023] S2: Combine the relative displacement and relative rotation angle obtained in S1 with the world coordinates of the pilot robot to obtain the world coordinates and posture of each follower robot based on the onboard sensor of the pilot robot;

[0024] S3: Using the Kalman filter algorithm, the world coordinate and posture information of each following robot obtained by S2 is integrated with the current world coordinate and posture information obtained by its own vehicle-mounted sensor to obtain the actual world coordinate and posture information of each robot, thereby adjusting the current state of the robot to achieve navigation.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention connects the movable robot and the transported object through a cooperative device to form a multi-robot flexible connection cooperative transportation system, so that the cooperative transportation of three or more robots becomes possible, and the robustness of the control of the multi-robot cooperative transportation formation is improved; the relative error detection between the mobile robot and the transported object is more convenient; the error of the follower robot can be fed back to the active robot. Specifically: compared with the conventional large-scale carrier platform, it is more flexible; compared with the general system that can only carry out cooperative transportation with two robots, the present invention can be applied to three or more robots; the relative movement of the cooperative support block and the cooperative base plate supports the robot to carry out cooperative transportation within a wider range of deviations; the error detection using camera vision is simple and fast, and the encoder and displacement sensor are omitted to directly detect relative displacement and relative rotation through vision; the Kalman filter is used to obtain a more accurate posture and position of each robot; the errors of multiple robots can be fed back to the active robot, so that the active robot can adjust according to the errors of the remaining robots, and the robustness of the cooperative transportation control is higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a simplified structural diagram of the multi-mobile robot flexible connection cooperative transportation system of this embodiment 1;

[0028] Figure 2 To follow the assembly exploded view of the collaborative device;

[0029] Figure 3A state diagram of a characteristic mark being recognized by a camera when working with a cooperative device;

[0030] Figure 4 for Figure 3 Bottom view of

[0031] Figure 5 This is the assembly exploded view of the pilot coordination device;

[0032] Figure 6 The structure diagram of the cooperative device for installing support top plates of different structures; wherein (a) is a common support plate; (b) is a foam support plate; (c) is a V-shaped support plate;

[0033] Figure 7 This is a schematic diagram of the structure of a multi-mobile robot flexibly connected cooperative transportation system according to Example 2 of the present invention.

[0034] Among them: 1-1 is the pilot cooperative device, 1-2 is the follower cooperative device; 2 is the pilot robot; 3 is the first follower robot; 4 is the transported object; 5 is the second follower robot; 6 is the support top plate; 7 is the cooperative support block; 8 is the buffer pad; 9 is the second lubricating plate; 10 is the first lubricating plate; 11 is the camera; 12 is the spring; 13 is the cooperative outer ring; 14 is the cooperative bottom plate; 15 is the support cylinder; 16 is the characteristic mark; 17 is the ordinary support plate; 18 is the foam support plate; 19 is the V-shaped support plate. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0036] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0037] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0038] Example 1

[0039] See also Figure 1 , is a multi-mobile robot flexible connection cooperative transportation system disclosed in the present invention, which is composed of multiple movable robots that are flexibly connected to the transported objects 4 through cooperative devices. Figure 1 The figure shows a schematic diagram of three mobile robots cooperatively transporting objects based on the pilot-following strategy, including a pilot robot 2, a first follower robot 3, a second follower robot 5 and a transported object 4. The pilot robot 2 cooperates with the transported object 4 through the pilot cooperation device 1-1, and the first follower robot 3 and the second follower robot 5 cooperate with each other through the follower cooperation devices 1-2 respectively set.

[0040] Figure 2 The exploded view of the assembly of the following cooperative device 1-2 is shown. The following cooperative device 1-2 includes a supporting top plate 6, a cooperative supporting block 7, a buffer pad 8, a first lubricating sheet 10, a second lubricating sheet 9, a camera 11, a spring 12, a cooperative outer ring 13, a cooperative bottom plate 14, a supporting cylinder 15 and a characteristic mark 16. Among them, the first lubricating sheet 10 and the second lubricating sheet 9 are made of brass graphite sheets as lubricating sheets, and the supporting top plate 6, the cooperative supporting block 7 and the second lubricating sheet 9 are connected, and relative rotation and relative displacement occur relative to the first lubricating sheet 10. The rotation and displacement of the characteristic mark 16 are scanned by the camera 11 to detect the relative displacement and relative rotation of the following robot relative to the transported object 4. The collaborative devices are respectively located on the movable pilot robot and the follower robot, and are connected to the transported object 4 through the support plate top 6. The first follower robot 3 and the second follower robot 5 obtain their own posture and position information by combining the posture and position information of the pilot robot 2 with the errors detected by the following collaborative devices 1-2 thereon, and use Kalman filtering to fuse the posture and position information obtained by other sensors to obtain more accurate posture and position, and actively adjust their motion state to reduce errors.

[0041] Figure 3 The following diagram is a schematic diagram of the structural changes of the initial state and the working state of the following cooperative device 1-2, wherein the cooperative support block 7 is connected to the cooperative outer ring 13 through the spring 12, and when the following cooperative device 1-2 does not contact the transported object 4, the cooperative support block 7 returns to and maintains the initial position through the combined force of the three springs 11. After the following cooperative device 1-2 is connected to the transported object 4, when the two following robots and the transported object 4 undergo relative displacement and relative rotation, the second lubricating plate 9 and the first lubricating plate 10 undergo relative displacement and relative rotation, wherein the buffer pad 8 plays a role of limiting and buffering.

[0042] Figure 4 for Figure 3 In the top view corresponding to the following collaborative device 1-2 shown, the characteristic mark 16 on the collaborative support block 7 corresponds to the movement of the collaborative support block 7. The relative displacement and relative rotation of the collaborative support block 7 relative to the two follower robots are detected and calculated by the camera 11, and then the relative displacement and relative rotation of the three mobile robots relative to the transported object 4 can be obtained. Then, the world coordinates and posture of the two follower robots can be obtained through the world coordinates and posture of the pilot robot 2. The world coordinates and posture of the two follower robots are merged with the current world coordinates and posture obtained by the sensors thereon by Kalman filtering, and the actual world coordinates and posture of the two follower robots are obtained to provide feedback and adjust the current state of the robots, so as to realize robot collaborative control navigation.

[0043] Figure 5 This is an exploded view of the assembly of the pilot cooperative device 1-1 of the pilot robot 2. It is similar to the follower cooperative device 1-2 of the follower robot, but the outer diameter of the cooperative support block 7 and the second lubricating plate 9 of the pilot robot 2 is the same as the inner diameter of the buffer pad 8, that is, the cooperative support block 7 in the pilot cooperative device 1-1 of the pilot robot 2 is limited by the buffer pad 8 and can only rotate relative to each other. This can not only ensure that the relative displacement between the pilot robot 2 and the transported object 4 is fixed, but also ensure that the transported object 4 and the follower robot have effective relative displacement during startup and operation.

[0044] Figure 6 It is a schematic diagram of the structure of different support top plates 6, wherein the ordinary support plate 17 is used for the transportation of general objects, the foam support plate 18 is used for objects with curved surfaces or fragile objects such as glass, and the V-shaped support plate 19 is used for objects with cylindrical features. Correspondingly, if there are other special needs, a special support top plate 6 can be used for transportation. Different support top plates 6 can be used in combination in the robot collaborative transportation system, and different robots can be equipped with different support top plates 6 to complete the collaborative transportation task.

[0045] Example 2

[0046] See also Figure 7 , which is different from Example 1, is a structural diagram of four robots cooperating in handling. The four robots include a pilot robot 2, a follower robot A 20, a follower robot B 21 and a follower robot C 22. The device can be applied to situations where multiple robots cooperate in handling.

[0047] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A multi-robot flexible connection cooperative transportation system, characterized in that: It comprises a pilot robot (2) and a plurality of follower robots, a follower coordination device (1-2) is arranged on the top of each follower robot, a pilot coordination device (1-1) is arranged on the top of the pilot robot (2), and the pilot coordination device (1-1) and the plurality of follower coordination devices (1-2) cooperate to transport a transported object (4); In the following cooperative device (1-2), an image acquisition device for detecting and feeding back the relative displacement and relative rotation of the following robot is provided; The following cooperative device (1-2) is provided with a supporting top plate (6), a cooperative outer ring (13), a first lubricating sheet (10) and a cooperative bottom plate (14) in order from top to bottom; a cooperative supporting block (7) and a second lubricating sheet (9) are stacked in the cavity of the cooperative outer ring (13); buffer pads (8) for limiting and buffering are distributed on the inner wall of the cooperative outer ring (13); one end of the spring (12) is fixed on the cooperative supporting block (7), and the other end is fixed on the inner wall of the cooperative outer ring (13) between adjacent buffer pads (8); wherein the inner diameter of the first lubricating sheet (10) in the following cooperative device (1-2) is larger than the inner diameter of the second lubricating sheet (9); a characteristic mark (16) is provided at the bottom of the first lubricating sheet (10); the first lubricating sheet (10) and the cooperative bottom plate (14) are provided with holes that penetrate each other; and an image acquisition device is provided at the bottom of the cooperative bottom plate (14) for acquiring position information of the characteristic mark (16); The pilot cooperative device (1-1) is provided with a supporting top plate (6), a cooperative outer ring (13), a first lubricating plate (10) and a cooperative bottom plate (14) in order from top to bottom; a cooperative supporting block (7) and a second lubricating plate (9) are stacked in the cavity of the cooperative outer ring (13), and a buffer pad (8) for limiting and buffering is distributed on the inner wall of the cooperative outer ring (13); wherein the first lubricating plate (10) and the second lubricating plate (9) in the pilot cooperative device (1-1) have the same inner diameter size, and the inner diameter of the buffer pad (8) is the same as the outer diameter size of the second lubricating plate (9).

2. The multi-robot flexible connection cooperative transportation system according to claim 1 is characterized in that: The first lubricating sheet (10) and the second lubricating sheet (9) are made of brass graphite sheets.

3. The multi-robot flexible connection cooperative transportation system according to claim 1 is characterized in that: A plurality of supporting columns (15) connected to the robot are also provided at the bottom of the cooperative bottom plate (14).

4. The multi-robot flexible connection cooperative transportation system according to claim 1 is characterized in that: The supporting top plate (6) comprises a common supporting plate (19) with holes, a foam supporting plate (20) and a supporting plate (21) with a V-shaped bracket.

5. The multi-robot flexible connection cooperative transportation system according to claim 1, characterized in that: It is characterized in that The image acquisition device is a camera, a video camera or a camera.

6. The multi-robot flexible connection cooperative transportation system according to claim 1, characterized in that: It is characterized in that The number of the following robots is 2 or 3.

7. The multi-robot flexible connection cooperative transportation system according to claim 1 is characterized in that: The following cooperative device (1-2) and the pilot cooperative device (1-1) are also provided with vehicle-mounted sensors, and there are three types of vehicle-mounted sensors, namely, a wheel encoder, a vehicle-mounted radar and an inertial navigation device; among them: Wheel encoder, used to detect the displacement and running speed of the robot; Onboard radar, used to identify the geometric features of the operating environment and move the robot's global position and global posture; The inertial navigation device is used to detect the linear acceleration, linear velocity, angular acceleration and angular velocity of the robot's motion.

8. The visual error navigation method of the multi-robot flexible connection cooperative transportation system according to claim 7 is characterized in that: The following steps are involved: S1: Detect the relative displacement and relative rotation angle between each follower robot and the transported object through an image acquisition device; S2: Combine the relative displacement and relative rotation angle obtained in S1 with the world coordinates of the pilot robot to obtain the world coordinates and posture of each follower robot based on the onboard sensor of the pilot robot; S3: Using the Kalman filter algorithm, the world coordinate and posture information of each following robot obtained by S2 is integrated with the current world coordinate and posture information obtained by its own vehicle-mounted sensor to obtain the actual world coordinate and posture information of each robot, thereby adjusting the current state of the robot to achieve navigation.

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