A dual AGV collaborative handling system and control method thereof

Abstract

The present invention belongs to the field of intelligent manufacturing and flexible manufacturing, and discloses a dual AGV collaborative handling system and a control method thereof, including a pilot AGV, a follower AGV and a shelf; the pilot AGV and the follower AGV are respectively connected to the bottom ends of the shelf, and the pilot AGV and the follower AGV are connected in communication; a first status information acquisition device is provided on the pilot AGV, and the first status information acquisition device is used to acquire the status information of the pilot AGV and send it to the follower AGV through the pilot AGV; a second status information acquisition device is provided on the follower AGV, and the second status information acquisition device is used to acquire the status information of the follower AGV and send it to the follower AGV, and the follower AGV is used to adjust its own position according to the status information of the pilot AGV and the status information of the follower AGV. The dual AGV collaborative handling system and the control method thereof of the present invention realize better handling and processing for the problem of handling large components that are difficult to be effectively carried out by a single AGV.

Description

Technical Field

[0001] The invention belongs to the field of intelligent manufacturing and flexible manufacturing, and relates to a dual AGV collaborative handling system and a control method thereof. Background Art

[0002] In actual manufacturing scenarios, AGV (Automated Guided Vehicle) is often used to replace manpower to perform repetitive handling and transportation tasks between several fixed workstations. It has been widely used in production automation logistics systems in industries such as automobiles, aviation manufacturing plants, and warehousing and logistics.

[0003] However, in some large and complex handling scenarios, such as in aircraft and high-speed rail assembly lines, the handling process of large components still mainly relies on manually operated gantry cranes, cranes and other large equipment, making the efficiency of the entire system low. The maximum handling capacity of the AGV-based handling system depends on the maximum carrying capacity of a single AGV. In the above large-scale manufacturing scenarios, the existing industrial AGVs are slightly insufficient in terms of function, efficiency, carrying capacity and stability. However, the development of AGVs with more powerful functions and greater carrying capacity will increase manufacturing costs and operation and maintenance costs. At the same time, the guidance control performance and motion control capabilities of a single AGV will be limited, and the entire system has a high degree of customization, poor versatility and reusability. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcoming of low handling efficiency of large components in the above-mentioned prior art and to provide a dual AGV collaborative handling system and a control method thereof.

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

[0006] In a first aspect, the present invention provides a dual AGV collaborative handling system, including a pilot AGV, a following AGV and a shelf; the pilot AGV and the following AGV are respectively connected to the bottom ends of the shelf, and the pilot AGV and the following AGV are communicatively connected; a first status information acquisition device is provided on the pilot AGV, and the first status information acquisition device is used to acquire the status information of the pilot AGV and send it to the following AGV via the pilot AGV; a second status information acquisition device is provided on the following AGV, and the second status information acquisition device is used to acquire the status information of the following AGV and send it to the following AGV, and the following AGV is used to adjust its own position according to the status information of the pilot AGV and the status information of the following AGV.

[0007] Optionally, the pilot AGV and the follower AGV are connected via WIFI, 5G or wired communication; the pilot AGV and the follower AGV are both AGVs with differential chassis.

[0008] Optionally, the pilot AGV and the follower AGV are connected to the two ends of the bottom of the shelf through latches, or are connected to the two ends of the bottom of the shelf through bull's eye balls.

[0009] Optionally, the first status information acquisition device includes a first visual recognition device, the second status information acquisition device includes a second visual recognition device, the status information of the pilot AGV includes the position information of the pilot AGV, and the status information of the following AGV includes the position information of the following AGV; the first visual recognition device is used to obtain the position information of the pilot AGV by obtaining the position error information between the first preset positioning mark and itself, and the second visual recognition device is used to obtain the position information of the following AGV by obtaining the position error information between the second preset positioning mark and itself; wherein the first preset positioning mark and the second preset positioning mark are both marks preset on the shelf or the goods on the shelf.

[0010] Optionally, the following AGV is further configured to generate control information of the pilot AGV according to the status information of the pilot AGV and the status information of the following AGV and send the control information to the pilot AGV, and the pilot AGV is configured to control its own operating status according to the control information of the pilot AGV.

[0011] In a second aspect, the present invention provides a control method for the dual AGV collaborative handling system, comprising:

[0012] Obtain the operation constraint information of the leading AGV and the following AGV;

[0013] The following AGV obtains the target position information of the following AGV according to the state information of the leading AGV and the state information of the following AGV, as well as the operation constraint information of the leading AGV and the following AGV;

[0014] The following AGV obtains the control information of the following AGV according to the target position information and the state information of the following AGV, and controls its own running state according to the control information of the following AGV.

[0015] Optionally, the control method of the dual AGV collaborative handling system further includes:

[0016] According to the status information of the pilot AGV and the status information of the follower AGV, the distance between the pilot AGV and the follower AGV is obtained;

[0017] When the distance between the pilot AGV and the following AGV exceeds a preset safety threshold, the following AGV generates a stop command for the pilot AGV and sends it to the pilot AGV. The pilot AGV responds to the stop command of the pilot AGV and stops running.

[0018] When the pilot AGV is in a stopped state and the distance between the pilot AGV and the following AGV exceeds a preset safety threshold, the following AGV generates a start command for the pilot AGV and sends it to the pilot AGV. The pilot AGV responds to the start command of the pilot AGV and starts running.

[0019] Optionally, the following AGV obtains the target position information of the following AGV according to the state information of the leading AGV and the state information of the following AGV, and the operation constraint information of the leading AGV and the following AGV, including:

[0020] The position information of the pilot AGV at time k+1 is obtained by the following formula:

[0021]

[0022]

[0023] in, is the position information of the pilot AGV at time k, is the speed information of the pilot AGV at time k, ΔT is the sampling interval, The position of the pilot AGV at time k+1 predicted at time k;

[0024] The forward angle of the following AGV from time k to time k+1 is obtained by the following formula:

[0025]

[0026] in, The position of the pilot AGV at k+1 And follow the AGVk's position at the moment The location is determined;

[0027] The predicted position information of the following AGV at time k+1 is obtained by the following formula:

[0028]

[0029]

[0030] in, To follow the position of the AGV at time k, To follow the speed of AGV at time k, ΔT is the sampling interval, is the linear velocity direction of the AGV at time k;

[0031] The predicted position information of the following AGV at time k+1 is corrected by the following formula to obtain the target position information (x, y) of the following AGV at time k+1:

[0032]

[0033] Among them, dist ref is the rated distance between the pilot AGV and the following AGV. is the position of the pilot AGV at time k+1, is the position of the following AGV at time k+1.

[0034] Optionally, the following AGV obtains the control information of the following AGV according to the target position information and the state information of the following AGV, including:

[0035] The tracking error of the following AGV at time k is obtained by the following formula:

[0036]

[0037] Among them, (x e ,y e ,θ e ) is the tracking error of the following AGV to the target position defined in the global coordinate system, (e x ,e y ,e θ ) is the tracking error of the following AGV to the target position defined in the vehicle coordinate system, and θ is the angle of the following AGV;

[0038] According to the tracking error of the following AGV at time k, the tracking error elimination control information of the following AGV is obtained by the following formula:

[0039]

[0040] Among them, (v r ,w r ) is the reference speed and angular velocity on the target trajectory of the AGV, k 1 ,k 2 and k 3 are the parameters in the control law, both are non-zero positive numbers;

[0041] The reference speed and reference angular velocity of the following AGV are obtained by the following formula:

[0042]

[0043]

[0044]

[0045] in, To follow the position of the AGV at time k, To follow the position of the AGV at time k+1, To follow the linear velocity direction of AGV at time k, (v r ,w r ) is the reference speed and angular velocity of the following AGV at the target position at time k, ΔT is the sampling interval;

[0046] According to the tracking error elimination control information of the following AGV and the reference operation information, the control information of the following AGV is obtained.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] The dual AGV collaborative handling system of the present invention adopts dual AGVs for collaborative handling. Based on the settings of the first status information acquisition device and the second status information acquisition device, it can obtain the status information of the pilot AGV and the status information of the follower AGV in real time, so that the follower AGV can completely and dynamically follow the movement process of the pilot AGV, and can effectively eliminate the errors generated during the movement. During the movement of the follower AGV, its direction is always toward the forward direction of the pilot AGV. Therefore, the path taken by the follower AGV at each sampling moment is a straight line trajectory pointing to the pilot AGV, ensuring that the distance between the two AGVs is stable during the entire handling process, so that the AGV and the goods being carried on the shelf will not be subjected to stress between each other, ensuring the stable operation of the dual AGV collaborative handling system. It can be seen that the dual AGV collaborative handling system achieves better handling and processing for the problem of handling large components that are difficult to be effectively carried out by a single AGV.

[0049] The control method of the dual AGV collaborative transport system of the present invention is based on the status information of the pilot AGV and the status information of the follower AGV, combined with the operation constraint information of the pilot AGV and the follower AGV, to achieve the acquisition of the target position information of the follower AGV and the generation of control information, so that the follower AGV can completely and dynamically follow the movement process of the pilot AGV, and can effectively eliminate the errors generated in the movement process; during the movement of the follower AGV, its direction is always toward the forward direction of the pilot AGV, therefore, the path taken by the follower AGV at each sampling moment is a straight line trajectory pointing to the pilot AGV, and the distance traveled is the shortest distance under the constraints; thanks to the target position generation method of the follower AGV, the speed of the follower AGV will not be greater than the speed of the pilot AGV, therefore, the speed of the entire collaborative transport system can be controlled by the movement speed of the pilot AGV, and the control is stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Schematic diagram of the structure of a dual AGV collaborative handling system according to an embodiment of the present invention.

[0051] Figure 2This is a flow chart of a control method of a dual AGV collaborative handling system according to an embodiment of the present invention.

[0052] Figure 3 This is a detailed flow chart of the control method of the dual AGV collaborative handling system according to an embodiment of the present invention.

[0053] Figure 4 It is a schematic diagram of the principle of calculating the target position of the follow-up AGV according to the status information of two AGVs according to an embodiment of the present invention.

[0054] Figure 5 The embodiment of the present invention is based on the distance constraint between the two AGVs F k+1|k Schematic diagram of the principle of correcting the position.

[0055] Figure 6 is a schematic diagram of the error between the position of the following AGV and the target position according to an embodiment of the present invention, wherein X F O F Y F The vehicle body coordinate system is established on the following AGV, the coordinate origin is the geometric center of the following AGV, and the X-axis direction is the speed direction of the following AGV.

[0056] Figure 7 This is a physical experiment trajectory diagram of two AGVs cooperating in transporting objects according to an embodiment of the present invention.

[0057] Figure 8 Schematic diagram of the distance fluctuation between two AGVs during the experiment of an embodiment of the present invention.

[0058] Fig. 9 Graph showing the linear speeds of two AGVs during the experiment of an embodiment of the present invention.

[0059] Fig.10 Angular velocity curves of two AGVs during the experiment of an embodiment of the present invention.

[0060] Among them: 1-Pilot AGV; 2-Following AGV; 3-Shelf. DETAILED DESCRIPTION

[0061] 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.

[0062] 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.

[0063] In response to the problems in the background technology, the inventors found in actual work that two existing, low-cost and easy-to-integrate AGVs can be used for collaborative transportation, which can greatly improve manufacturing efficiency and has very important scientific value and practical significance.

[0064] Based on this, the present invention proposes a dual AGV collaborative handling system, including a pilot AGV1, a follower AGV2 and a shelf 3; the pilot AGV1 and the follower AGV2 are respectively connected to the bottom ends of the shelf 3, and the pilot AGV1 and the follower AGV2 are in communication connection; a first status information acquisition device is provided on the pilot AGV1, and the first status information acquisition device is used to acquire the status information of the pilot AGV1 and send it to the follower AGV2 through the pilot AGV1; a second status information acquisition device is provided on the follower AGV2, and the second status information acquisition device is used to acquire the status information of the follower AGV2 and send it to the follower AGV2, and the follower AGV2 is used to adjust its own position according to the status information of the pilot AGV1 and the status information of the follower AGV2. The dual AGV collaborative handling system adopts dual AGVs for collaborative handling, and achieves better handling for the problem of handling large parts that are difficult to be effectively carried out by a single AGV.

[0065] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0066] See also Figure 1In one embodiment of the present invention, a dual AGV collaborative handling system is provided, including a pilot AGV1, a follower AGV2 and a shelf 3; the pilot AGV1 and the follower AGV2 are respectively connected to the two ends of the bottom of the shelf 3, and the pilot AGV1 and the follower AGV2 are in communication connection; a first status information acquisition device is provided on the pilot AGV1, and the first status information acquisition device is used to acquire the status information of the pilot AGV1 and send it to the follower AGV2 through the pilot AGV1; a second status information acquisition device is provided on the follower AGV2, and the second status information acquisition device is used to acquire the status information of the follower AGV2 and send it to the follower AGV2, and the follower AGV2 is used to adjust its own position according to the status information of the pilot AGV1 and the status information of the follower AGV2.

[0067] Among them, the leading AGV1 and the following AGV2 adopt a front-to-back connected layout. Each AGV is equipped with a lifting mechanism on the top to lift and transport the shelf 3. The two AGVs are connected by a rectangular shelf or bracket.

[0068] In summary, the dual AGV collaborative handling system of the present invention uses dual AGVs for collaborative handling. Based on the settings of the first status information acquisition device and the second status information acquisition device, it can obtain the status information of the pilot AGV and the status information of the follower AGV in real time, so that the follower AGV can completely and dynamically follow the movement process of the pilot AGV, and can effectively eliminate the errors generated during the movement. During the movement of the follower AGV, its direction is always toward the forward direction of the pilot AGV. Therefore, the path taken by the follower AGV at each sampling moment is a straight line trajectory pointing to the pilot AGV, ensuring that the distance between the two AGVs is stable during the entire handling process, so that the AGV and the goods being carried on the shelf will not be subject to stress between each other, ensuring the stable operation of the dual AGV collaborative handling system. It can be seen that the dual AGV collaborative handling system has achieved better handling and processing for the problem of handling large components that are difficult to be effectively carried out by a single AGV.

[0069] In a possible implementation manner, the pilot AGV1 and the follower AGV2 are connected to each other through WIFI, 5G or wired communication; the pilot AGV1 and the follower AGV2 are both AGVs with differential chassis.

[0070] Optionally, the pilot AGV 1 and the follower AGV 2 are connected to the bottom ends of the shelf 3 through a latch, or connected to the bottom ends of the shelf 3 through a bull's eye ball. When the connection is achieved through a bull's eye ball, the sliding of the bull's eye ball can ensure the allowable range of error.

[0071] Optionally, the first status information acquisition device includes a first visual recognition device, the second status information acquisition device includes a second visual recognition device, the status information of the pilot AGV1 includes the position information of the pilot AGV1, and the status information of the following AGV2 includes the position information of the following AGV2; the first visual recognition device is used to obtain the position information of the pilot AGV1 by obtaining the position error information between the first preset positioning mark and itself, and the second visual recognition device is used to obtain the position information of the following AGV2 by obtaining the position error information between the second preset positioning mark and itself; wherein the first preset positioning mark and the second preset positioning mark are both marks preset on shelf 3 or the goods on shelf 3.

[0072] The identification preset on the shelf 3 or the goods on the shelf 3 may be a label or a QR code. The first visual recognition device and the second visual recognition device are used to align with the label or QR code on the shelf or the goods to correct the positions of the pilot AGV1 and the follower AGV2. The distance between the pilot AGV1 and the follower AGV2 can be adjusted according to the actual handling situation.

[0073] See also Figure 2 In another embodiment of the present invention, a control method for the dual AGV collaborative handling system is provided, comprising the following steps:

[0074] S1: Obtain the operation constraint information of the leading AGV1 and the following AGV2.

[0075] S2: The following AGV2 obtains the target position information of the following AGV2 according to the state information of the leading AGV1 and the state information of the following AGV2, as well as the operation constraint information of the leading AGV1 and the following AGV2.

[0076] S3: The following AGV2 obtains the control information of the following AGV2 according to the target position information and the state information of the following AGV2, and controls its own running state according to the control information of the following AGV2.

[0077] In summary, the control method of the dual AGV collaborative transport system of the present invention is based on the status information of the pilot AGV1 and the status information of the follower AGV2, combined with the operation constraint information of the pilot AGV1 and the follower AGV2, to achieve the acquisition of the target position information of the follower AGV2 and the generation of control information, so that the follower AGV2 can completely and dynamically follow the movement process of the pilot AGV1, and can effectively eliminate the errors generated during the movement process; during the movement of the follower AGV2, its direction is always toward the forward direction of the pilot AGV1, therefore, the path taken by the follower AGV2 at each sampling moment is a straight line trajectory pointing to the pilot AGV1, and the distance traveled is the shortest distance under the constraints; thanks to the target position generation method of the follower AGV2, the speed of the follower AGV2 will not be greater than the speed of the pilot AGV1, therefore, the speed of the entire collaborative transport system can be controlled by the movement speed of the pilot AGV1, and the control is stable.

[0078] In a possible real-time mode, the control method of the dual AGV collaborative handling system also includes: obtaining the distance between the pilot AGV1 and the follower AGV2 according to the status information of the pilot AGV1 and the status information of the follower AGV2; when the distance between the pilot AGV1 and the follower AGV2 exceeds a preset safety threshold, the follower AGV2 generates a stop command for the pilot AGV1 and sends it to the pilot AGV1, and the pilot AGV1 responds to the stop command of the pilot AGV1 and stops running; when the pilot AGV1 is in a stopped running state and the distance between the pilot AGV1 and the follower AGV2 exceeds the preset safety threshold, the follower AGV2 generates a start command for the pilot AGV1 and sends it to the pilot AGV1, and the pilot AGV1 responds to the start command of the pilot AGV1 and starts running.

[0079] In a possible real-time mode, the control method of the dual AGV collaborative transport system of the present invention is composed of a front-to-back layout of two AGVs with differential chassis. In combination with the characteristics of the collaborative transport problem, the Leader-Follower method is used to calculate the target trajectory of the follower AGV2 in real time, and combined with the control law of trajectory tracking and correction, a system model of dual AGV collaborative transport is constructed. The judgment condition is that the distance between the two AGVs always meets the restriction, thereby achieving stable and reliable collaborative operation of the dual AGV collaborative transport system.

[0080] See also Figure 3 In this embodiment, the control method of the dual AGV collaborative handling system includes the following steps:

[0081] Step 1: According to the size of the parts to be transported or the length of the shelf, adjust the initial positions of the two AGVs so that the distance between the two AGVs meets the size of the goods for this transport task; at the same time, set up the communication environment. You can choose WIFI, 5G or wired communication methods to enable the two AGVs to start communicating with each other. The information that needs to be exchanged includes status information such as posture and speed and obstacle avoidance start and stop control instructions.

[0082] Step 2: The pilot AGV1 sends its own status information to the follower AGV2. The follower AGV2 combines the pilot AGV1 and its own status information to calculate the target position information at each moment in real time.

[0083] Step 3: Follow AGV2 to calculate the control amount required to reach the target position at each moment based on the deviation between its own position and the target position, and continue to send the calculated control amount to the chassis until the handling task is completed.

[0084] Step 4: The pilot AGV1 navigates forward according to the path of the handling task, and the following AGV2 tracks the pilot AGV1 according to the control amount in step 3; at the same time, the following AGV2 monitors the distance fluctuation between the two AGVs. When the distance exceeds the safety threshold, the following AGV2 sends a stop command to the pilot AGV1. At the same time, the following AGV2 adjusts its own position according to the control amount in step 3 to eliminate the distance deviation between the two AGVs. When the distance meets the safety threshold, the pilot AGV1 continues to follow the front vehicle until the handling task is completed.

[0085] Optional, see Figure 4 In step 2, the idea of ​​Leader-Follower is adopted to combine the posture information of the two AGVs to calculate the target position for the follower AGV2. The specific steps include:

[0086] Step 2.1: Collect the position and speed information of the leading AGV1 and the following AGV2 at time k: Correspondingly, the position information of the pilot AGV1 at time k+1 is calculated as:

[0087]

[0088]

[0089] in, and are the position and speed information of the pilot AGV1 at time k, ΔT is the sampling interval, is the position of the pilot AGV1 at time k+1 predicted at time k.

[0090] Step 2.2: Define the Angle That is, follow the forward angle of AGV2 at each moment:

[0091]

[0092] in, The position of the pilot AGV at k+1 And follow the AGVk's position at the moment The location is determined;

[0093] angle is the inertial coordinate system X-axis and L k+1|k and F k The angle between the connecting lines is calculated as follows:

[0094]

[0095]

[0096] in, and are the position and linear velocity of the following AGV2 at time k, ΔT is the sampling interval, is the linear velocity direction of AGV2 at time k.

[0097] Step 2.3: See Figure 5 , according to the operation constraint information of the leading AGV1 and the following AGV2, that is, the distance constraint of the leading AGV1 and the following AGV2, the predicted position information is corrected:

[0098]

[0099] Among them, dist ref is the rated distance between the pilot AGV1 and the following AGV2, and They are the positions of the leading AGV1 and the following AGV2 at time k+1 respectively. The calculated (x, y) is the accurate predicted position of the following AGV2 at time k+1.

[0100] At this point, the target position information that AGV2 needs to reach at each moment can be obtained.

[0101] Optional, see Figure 6 In step 3, the following AGV2 needs to calculate the control amount to achieve target position tracking based on the deviation between its position and the target position at each moment. The specific steps include:

[0102] Step 3.1: At time k, the positioning pose of the following AGV2 is [x, y, θ], and the target pose is [x r ,y r,θ r ], the tracking error at each moment can be converted to the vehicle coordinate system of AGV2 and calculated as:

[0103]

[0104] Among them, (x e ,y e ,θ e ) and (e x ,e y ,e θ ) are the tracking errors of the following AGV2 to the target position defined in the global coordinate system and the vehicle coordinate system, respectively, and θ is the angle of the following AGV2.

[0105] Step 3.2: Based on the tracking error in step 3.1, the control amount of AGV2 at each moment is:

[0106]

[0107] Among them, (v r ,w r ) is the reference speed and angular velocity on the target trajectory of AGV2, k 1 ,k 2 and k 3 are parameters in the control law, both of which are non-zero positive numbers.

[0108] Step 3.3: At the same time, the reference velocity and reference angular velocity on the target trajectory of AGV2 are calculated as follows:

[0109]

[0110]

[0111]

[0112] in, and are the positions of the following AGV2 at time k and time k+1 respectively, To follow the linear velocity direction of AGV2 at time k, (v r ,w r ) is the reference speed and angular velocity of AGV2 at the target position at time k, and ΔT is the sampling interval.

[0113] After the calculation and release of the speed and angular velocity of the following AGV2 at time k, the positions of the two AGVs will move to time k+1, and steps 2 and 3 will be repeated.

[0114] See also Figure 7, shows the actual experimental trajectory diagram of the collaborative handling of the pilot AGV1 and the follower AGV2, where the trajectory of the pilot AGV1 is a rounded rectangle, while the trajectory of the follower AGV2 is close to that of the pilot AGV1 in the straight stage, and the turning radius in the turning stage is smaller than that of the pilot AGV1, which ensures that the trajectory of the dual-AGV collaborative handling system can be completely determined by the motion trajectory of the pilot AGV1. At the same time, it ensures that the speed of the follower AGV will not exceed that of the pilot AGV1, ensuring the safety of the dual-machine collaborative handling system during the handling process; at the same time, 8 points on the trajectory are marked in the figure, so that the position of the shelf 3 during the handling process can be determined.

[0115] See also Figures 8 to 10 , showing the specific data during the actual experiment of collaborative handling between the leading AGV1 and the following AGV2.

[0116] in, Figure 8 This is the distance curve between the pilot AGV1 and the following AGV2. Compared with the rated distance of 3.28m, the distance between the pilot AGV1 and the following AGV2 is always kept within ±3cm; Fig. 9 and Fig.10 These are the linear speed and linear speed curve of the leading AGV1 and the following AGV2, respectively. During the handling process, the speed of the following AGV2 is always less than or equal to the speed of the leading AGV1, which is due to the target trajectory designed for the following AGV2. At the same time, the speed curve is smooth and has no mutations, which also reflects the stability of the motion process.

[0117] It can be seen that the control method of the dual AGV collaborative handling system of the present invention can ensure that the follower AGV follows the movement process of the lead AGV in a fully dynamic manner, and can effectively eliminate the errors generated in the handling process, so that the deviation between the distance between the two AGVs and the rated distance is kept within a very small range.

[0118] The above description is only a preferred embodiment of the present invention. It should be pointed out that the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make several improvements and substitutions within the technical scope of the present invention, and these improvements and substitutions should also be regarded as the protection scope of the present invention.

Claims

1. A control method for a dual AGV collaborative handling system, characterized in that: The dual AGV collaborative handling system comprises a pilot AGV (1), a follower AGV (2) and a shelf (3); The pilot AGV (1) and the follower AGV (2) are respectively connected to two ends of the bottom of the shelf (3), and the pilot AGV (1) and the follower AGV (2) are in communication connection; A first status information acquisition device is provided on the pilot AGV (1), and the first status information acquisition device is used to acquire status information of the pilot AGV (1) and send it to the following AGV (2) through the pilot AGV (1); a second status information acquisition device is provided on the following AGV (2), and the second status information acquisition device is used to acquire status information of the following AGV (2) and send it to the following AGV (2), and the following AGV (2) is used to adjust its own position according to the status information of the pilot AGV (1) and the status information of the following AGV (2); The control method comprises: Obtaining the operation constraint information of the leading AGV (1) and the following AGV (2); The following AGV (2) obtains the target position information of the following AGV (2) according to the state information of the leading AGV (1) and the state information of the following AGV (2), as well as the operation constraint information of the leading AGV (1) and the following AGV (2); The following AGV (2) obtains the control information of the following AGV (2) according to the target position information and the state information of the following AGV (2), and controls its own running state according to the control information of the following AGV (2); The control method of the dual AGV collaborative handling system also includes: According to the state information of the leading AGV (1) and the state information of the following AGV (2), the distance between the leading AGV (1) and the following AGV (2) is obtained; When the distance between the pilot AGV (1) and the follower AGV (2) exceeds a preset safety threshold, the follower AGV (2) generates a stop command for the pilot AGV (1) and sends it to the pilot AGV (1), and the pilot AGV (1) responds to the stop command of the pilot AGV (1) and stops running; When the pilot AGV (1) is in a stopped state and the distance between the pilot AGV (1) and the following AGV (2) meets a preset safety threshold, the following AGV (2) generates a start command for the pilot AGV (1) and sends it to the pilot AGV (1), and the pilot AGV (1) responds to the start command of the pilot AGV (1) and starts running; The following AGV (2) obtains the target position information of the following AGV (2) according to the state information of the leading AGV (1) and the state information of the following AGV (2), as well as the operation constraint information of the leading AGV (1) and the following AGV (2), including: The position information of the pilot AGV (1) at time k+1 is obtained by the following formula: in, is the position information of the pilot AGV (1) at time k, is the speed information of the pilot AGV (1) at time k, ΔT is the sampling interval, is the position of the pilot AGV (1) at time k+1 predicted at time k; The forward angle of the following AGV (2) from time k to time k+1 is obtained by the following formula: in, The position of the pilot AGV (1) at time k+1 and the position of the following AGV (2) at time k The location is determined; The predicted position information of the following AGV (2) at time k+1 is obtained by the following formula: in, To follow the position of AGV (2) at time k, is the speed of AGV (2) at time k, ΔT is the sampling interval, is the linear velocity direction of the following AGV (2) at time k; The predicted position information of the following AGV (2) at time k+1 is corrected by the following formula to obtain the target position information (x, y) of the following AGV (2) at time k+1: Among them, dist ref is the rated distance between the pilot AGV (1) and the following AGV (2), is the position of the pilot AGV (1) at time k+1, is the position of the following AGV (2) at time k+1.

2. The control method of the dual AGV collaborative handling system according to claim 1, characterized in that: The following AGV (2) obtains the control information of the following AGV (2) according to the target position information and the state information of the following AGV (2), including: The tracking error of the following AGV (2) at time k is obtained by the following formula: Among them, (x e ,y e ,θ e ) is the tracking error of the target position of the following AGV (2) defined in the global coordinate system, (e x ,e y ,e θ ) is the tracking error of the following AGV (2) to the target position defined in the vehicle coordinate system, and θ is the angle of the following AGV (2); According to the tracking error of the following AGV (2) at time k, the tracking error elimination control information of the following AGV (2) is obtained by the following formula: Among them, (v r ,w r ) are the reference speed and angular velocity of the target trajectory of the AGV (2), k1, k2 and k3 are the parameters in the control law, all of which are non-zero positive numbers; The reference speed and reference angular velocity of the following AGV (2) are obtained by the following formula: in, To follow the position of AGV (2) at time k, To follow the position of AGV (2) at time k+1, is the linear velocity direction of the following AGV (2) at time k, (v r ,w r ) is the reference speed and angular velocity of the following AGV (2) at the target position at time k, ΔT is the sampling interval; According to the tracking error elimination control information and the reference operation information of the following AGV (2), the control information of the following AGV (2) is obtained.

3. The control method of the dual AGV collaborative handling system according to claim 1, characterized in that: The pilot AGV (1) and the follower AGV (2) are connected to each other by WIFI, 5G or wired communication; the pilot AGV (1) and the follower AGV (2) are both AGVs with differential chassis.

4. The control method of the dual AGV collaborative handling system according to claim 1, characterized in that: The pilot AGV (1) and the follower AGV (2) are respectively connected to the two ends of the bottom of the shelf (3) through latches, or connected to the two ends of the bottom of the shelf (3) through bull's eye balls.

5. The control method of the dual AGV collaborative handling system according to claim 1, characterized in that: The first status information acquisition device includes a first visual recognition device, the second status information acquisition device includes a second visual recognition device, the status information of the pilot AGV (1) includes the position information of the pilot AGV (1), and the status information of the following AGV (2) includes the position information of the following AGV (2); the first visual recognition device is used to obtain the position information of the pilot AGV (1) by obtaining the position error information between the first preset positioning mark and itself, and the second visual recognition device is used to obtain the position information of the following AGV (2) by obtaining the position error information between the second preset positioning mark and itself; wherein the first preset positioning mark and the second preset positioning mark are both marks preset on the shelf (3) or the goods on the shelf (3).

6. The control method of the dual AGV collaborative handling system according to claim 1, characterized in that: The following AGV (2) is also used to generate control information of the leading AGV (1) based on the status information of the leading AGV (1) and the status information of the following AGV (2) and send it to the leading AGV (1). The leading AGV (1) is used to control its own operating state based on the control information of the leading AGV (1).

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