AGV laser obstacle avoidance method based on safe PLC control

Abstract

The invention relates to the technical field of AGVs (Automatic Guided Vehicle), in particular to an AGV laser obstacle avoidance method based on safety PLC (Programmable Logic Controller) control, which adopts signal fusion of a safety laser radar and a plurality of sensors at an input level, adopts redundancy design, and adopts matching of a safety PLC and AGV master control at a decision level (a safety PLC layer serves as a main decision center). A plurality of flexible laser obstacle avoidance area switching strategies and safe AGV motion control (deceleration or power-off band-type brake) are adopted on the output level, redundancy design is also adopted, the overall system design safety is high, and the problems existing in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of AGV (Automated Guided Vehicle) vehicles, and more particularly to an AGV laser obstacle avoidance method based on safety PLC control. Background Art

[0002] In current field applications, AGVs are becoming increasingly popular in industries such as logistics and warehousing. They can effectively reduce labor costs and achieve higher levels of automation. However, how to avoid obstacles and collisions during the application process to protect personal and property safety has become a technical problem that AGVs must solve. In traditional technologies, AGV laser obstacle avoidance solutions use ordinary laser radars to perceive obstacles. The AGV master analyzes the acquired point cloud data and then formulates corresponding obstacle avoidance strategies. For example, patent publication number CN114564024A describes a forklift-type AGV laser obstacle avoidance control method. Old mobile phones use this method, which has problems such as low security and slow processing speed in data input, data processing, and decision output. This application is an improvement based on the existing technology, and adopts a safe laser radar for obstacle detection. Through the safe IO input and output of the safe laser radar, it has high security at the perception data input level; the safe PLC serves as the control center of the laser obstacle avoidance, and the AGV master control serves as an auxiliary to ensure the safety of the laser obstacle avoidance decision layer; the detection results of multiple sensors are comprehensively judged as the conditions for switching between different laser obstacle avoidance areas, and the processing speed is fast, which solves the problem of low security of the currently commonly used method of switching the laser obstacle avoidance area after the non-safe AGV master control determines the current state of the AGV. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide an AGV laser obstacle avoidance method based on safety PLC control, which has the advantages of

[0004] The above technical objectives of the present invention are achieved through the following technical solutions: an AGV laser obstacle avoidance method based on safety PLC control, comprising: Step S1: The AGV master control machine controls the AGV to move according to the scene requirements; Step S2: The safety PLC control layer generates a corresponding laser obstacle avoidance area switching instruction based on the AGV's location, the AGV's travel speed, and the AGV's cargo status. Step S3: The safety PLC control layer controls and adjusts the detection area of ​​the safety laser radar based on the generated laser obstacle avoidance area switching instruction; Step S4: When the safety laser radar detects an obstacle in the detection area, it transmits a signal to the safety PLC control layer to execute corresponding countermeasures.

[0005] Optionally, the area where the AGV in step S2 is located includes a normal moving area, a pick-up and placement area, and a complex area; according to the different working areas where the AGV is located, the safety PLC control layer generates a corresponding first judgment signal.

[0006] Optionally, the traveling speed of the AGV in step S2 includes several set speed intervals; according to the different speed intervals of the AGV, the safety PLC control layer generates a corresponding second judgment signal.

[0007] Optionally, the cargo consignment status of the AGV in step S2 includes a no-cargo status, a small pallet consignment status, and a large pallet consignment status; according to the cargo holding status of the AGV, the safety PLC control layer generates a corresponding third judgment signal.

[0008] Optionally, the safety PLC control layer in step S2 outputs corresponding laser obstacle avoidance area switching instructions according to different judgment signal combinations, including: increasing the detection area of ​​the safety laser radar, reducing the detection area of ​​the safety laser radar, turning off the safety laser radar, or turning on the safety laser radar.

[0009] Optionally, the AGV master computer in step S3 is bidirectionally connected to the safety PLC layer via CAN communication, for receiving the transmitted laser obstacle avoidance area switching instruction, and controlling and adjusting the detection area of ​​the safety laser radar according to the laser obstacle avoidance area switching instruction.

[0010] Optionally, the detection area of ​​the safety laser radar includes a deceleration area and a parking area.

[0011] Optionally, in step S4, when the safety laser radar identifies an obstacle in the deceleration zone within the detection area, it transmits a signal to the safety PLC layer, and the safety PLC layer transmits a deceleration control instruction to the AGV main control machine to execute the deceleration of the AGV vehicle drive wheel; when the safety laser radar identifies an obstacle in the parking area within the detection area, it transmits a signal to the safety PLC layer, and the safety PLC layer executes the motor power-off brake instruction to stop the AGV vehicle.

[0012] Optionally, step S2 also includes: the AGV main control machine detects the status of the AGV vehicle, and executes the laser obstacle avoidance area active switching instruction according to the working status of the AGV vehicle; the laser obstacle avoidance area active switching instruction includes: reducing the detection area of ​​the safety laser radar and turning off the safety laser radar.

[0013] Optionally, the working status of the AGV trolley includes: normal consignment working status, AGV trolley charging status and AGV trolley equipment docking status.

[0014] In summary, the present invention has the following beneficial effects: 1. At the input level, it uses signal fusion of safety laser radar and multiple sensors, and also adopts a redundant design. At the decision-making level, it adopts a combination of safety PLC + AGV master control (the safety PLC layer serves as the main decision-making center). At the output level, it adopts a variety of flexible laser obstacle avoidance area switching strategies and safe AGV motion control (deceleration or power-off braking) with a redundant design. The overall system design is highly secure.

[0015] 2. In actual application, by matching the corresponding laser obstacle avoidance areas according to different speed ranges, distinguishing the presence or absence of goods, and the laser obstacle avoidance areas during the picking and placing process, it can adapt to the requirements of extremely small channels, intelligent identification equipment docking, and intelligent identification of charging piles for automatic charging; according to the above trigger conditions, the combination of laser obstacle avoidance area switching trigger conditions is reasonable. According to the operating characteristics of the AGV car, different sensors and other signals are combined into a matrix management to match different laser obstacle avoidance areas to meet the scene condition requirements of the AGV car in different operating environments and different working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a flow chart of the method steps of the present invention; Figure 2 This is a schematic diagram of the logic flow of switching the laser obstacle avoidance detection area of ​​the present invention; Figure 3 It is a schematic diagram of the obstacle detection and countermeasure logic flow of the present invention. DETAILED DESCRIPTION

[0017] To make the objectives, features, and advantages of the present invention more readily apparent, the following detailed description of the present invention is provided with reference to the accompanying drawings. The accompanying drawings illustrate several embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein.

[0018] In the present invention, unless otherwise expressly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be a communication between the two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. The terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of such features.

[0019] In the present invention, unless otherwise expressly specified and limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature includes the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature. The terms "vertical," "horizontal," "left," "right," "above," "below," and similar expressions are for illustrative purposes only and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the present invention.

[0020] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0021] The present invention provides an AGV laser obstacle avoidance method based on safety PLC control, such as Figure 1 As shown, it includes step S1, the AGV master control machine controls the AGV car to move according to the scene requirements; Step S2: The safety PLC control layer generates a corresponding laser obstacle avoidance area switching instruction based on the AGV's location, the AGV's travel speed, and the AGV's cargo status. Step S3: The safety PLC control layer controls and adjusts the detection area of ​​the safety laser radar based on the generated laser obstacle avoidance area switching instruction; Step S4: When the safety laser radar detects an obstacle in the detection area, it transmits a signal to the safety PLC control layer to execute corresponding countermeasures.

[0022] Specifically, in actual application, a sensor array is installed on the AGV to identify the AGV's walking speed, the area where the AGV is located, and whether there is any cargo on the AGV, so as to facilitate subsequent identification and judgment; The signals transmitted by the above sensor arrays are all input into the safety PLC layer. After being processed by the safety PLC layer, the corresponding laser obstacle avoidance area switching instructions are transmitted to the AGV main control machine to realize the function of adjusting the detection area of ​​the safety laser radar to adapt to the working scene.

[0023] Furthermore, the area where the AGV in step S2 is located includes a normal moving area, a pick-up and placement area, and a complex area; according to the different working areas where the AGV is located, the safety PLC control layer generates a corresponding first judgment signal.

[0024] Specifically, the location of the AGV is identified through a GPS sensor or other position sensor, or through fixed marks such as QR codes and textures and laser slam, and then corresponded with the work map to identify the area where the AGV is located, and the signal is output to the safety PLC layer to generate a corresponding first judgment signal.

[0025] Specifically, the complex areas described above include but are not limited to areas with various obstacles, extremely narrow passages, and other areas where it is difficult to carry out work operations.

[0026] Furthermore, the traveling speed of the AGV in step S2 includes several set speed intervals; according to the different speed intervals of the AGV, the safety PLC control layer generates a corresponding second judgment signal.

[0027] Specifically, the non-IO signal of the AGV driving wheel speed is input into the safety PLC layer through speed sensors and other sensors that can identify the actual walking speed of the AGV. The safety PLC judgment layer judges the speed range based on the input speed. The speed ranges are high speed, medium speed, low speed and ultra-low speed. Each speed range matches a different laser obstacle avoidance area to output a corresponding different second judgment signal; the faster the speed, the larger the area, ensuring that the AGV can stably slow down or stop when encountering obstacles at any speed without causing a collision; similarly, if the AGV slows down due to the detection of obstacles or other reasons during movement, the laser obstacle avoidance area will also switch accordingly when the speed drops to the corresponding speed range.

[0028] Furthermore, the cargo consignment status of the AGV in step S2 includes a no-cargo status, a small pallet consignment status, and a large pallet consignment status; according to the cargo holding status of the AGV, the safety PLC control layer generates a corresponding third judgment signal.

[0029] Specifically, pressure sensors or laser sensors are used to identify whether there is checked cargo on the AGV and whether the checked cargo exceeds the size of the AGV, so as to distinguish large pallets from small pallets, and then output corresponding different third judgment signals; when the area of ​​the pallet is much larger than the AGV, even if the AGV is carrying cargo, it can adaptively match the appropriate laser obstacle avoidance area, and there will be no situation where the laser obstacle avoidance area cannot protect the pallet.

[0030] In other embodiments, sensors such as proximity switches and other sensors that can identify the position relationship of objects can also be used to sense the position of the AGV's motion mechanism, and then perceive the AGV's state, and then match the appropriate laser obstacle avoidance area based on the AGV's state, thereby further improving scene adaptability.

[0031] Furthermore, the safety PLC control layer in step S2 outputs corresponding laser obstacle avoidance area switching instructions according to different judgment signal combinations, including: increasing the detection area of ​​the safety laser radar, reducing the detection area of ​​the safety laser radar, turning off the safety laser radar, or turning on the safety laser radar.

[0032] Specifically, such as Figure 2 As shown, through the combination of the first judgment signal, the second judgment signal and the third judgment signal, the detection area size of the corresponding safety laser radar is matched and compared with the detection area size of the safety laser radar of the AGV vehicle in real time, and then the laser obstacle avoidance area switching instruction of increasing the detection area of ​​the safety laser radar, reducing the detection area of ​​the safety laser radar, turning off the safety laser radar or turning on the safety laser radar is output to adapt to actual application needs.

[0033] Furthermore, the AGV master computer in step S3 is bidirectionally connected to the safety PLC layer via CAN communication, for receiving the transmitted laser obstacle avoidance area switching instruction, and controlling and adjusting the detection area of ​​the safety laser radar according to the laser obstacle avoidance area switching instruction.

[0034] Furthermore, the detection area of ​​the safety laser radar includes a deceleration area and a parking area.

[0035] Furthermore, in step S4, when the safety laser radar identifies an obstacle in the deceleration zone within the detection area, it transmits a signal to the safety PLC layer, and the safety PLC layer transmits a deceleration control instruction to the AGV main control machine to execute the deceleration of the AGV vehicle drive wheel; when the safety laser radar identifies an obstacle in the parking area within the detection area, it transmits a signal to the safety PLC layer, and the safety PLC layer executes the motor power-off brake instruction to stop the AGV vehicle.

[0036] Specifically, such as Figure 3 As shown in the figure, when the safety laser radar identifies an obstacle in the deceleration zone within the detection area, the safety laser radar transmits a signal to the safety PLC layer. After processing, the safety PLC layer transmits a deceleration control instruction to the AGV master control machine to control the drive wheels to decelerate. The AGV master control must combine the signal from the input layer and the necessary decision signal from the safety PLC layer before outputting the execution action signal to the AGV. This design mechanism is also safer than simply controlling the execution action output of the AGV master control. like Figure 3As shown in the figure, when the safety laser radar identifies an obstacle in the parking area within the detection area, the safety laser radar transmits a signal to the safety PLC layer. After processing by the safety PLC layer, multiple actuator motors such as the walking mechanism and fork arm lifting mechanism on the AGV are equipped with brakes. The safety PLC layer can control the power off and brakes of all actuator motors, allowing the AGV to stop urgently to avoid the risk of collision or pinching.

[0037] Furthermore, step S2 also includes: the AGV main control machine detects the status of the AGV vehicle, and executes the laser obstacle avoidance area active switching instruction according to the working status of the AGV vehicle; the laser obstacle avoidance area active switching instruction includes: reducing the detection area of ​​the safety laser radar and turning off the safety laser radar.

[0038] Furthermore, the working status of the AGV trolley includes: normal consignment working status, AGV trolley charging status and AGV trolley equipment docking status.

[0039] In other embodiments, in actual scene applications, the AGV car will also perform various situations such as charging and device docking, which cannot be fully identified in the above combinations. At this time, the signal can be transmitted to the AGV main control through the external device function. After the AGV main control transmits the signal to the safety PLC layer for judgment, the safety PLC layer executes the laser obstacle avoidance area switching instruction, so that it can complete the effect of actively adjusting the detection area of ​​the safety laser radar, further improving the scene adaptability.

[0040] For example, when an AGV docks with equipment such as grounded rollers, if the normal laser obstacle avoidance area for pallet pickup and placement is used, the AGV may mistake the perceived equipment for an obstacle and encounter an obstacle. Through functions including but not limited to safety laser radar contour recognition, the AGV can intelligently identify the current equipment docking stage and switch to the corresponding laser obstacle avoidance area. For example, intelligent recognition of charging piles for automatic charging includes but is not limited to safety laser radar contour recognition functions, navigation QR codes posted on the ground and other markers. The AGV uses the above multiple recognition methods to confirm that it is currently in the automatic charging stage, and then switches to the corresponding laser obstacle avoidance area to ensure that the charging pile is not mistaken for an obstacle.

[0041] The present invention provides an AGV laser obstacle avoidance method based on safety PLC control, which adopts the signal fusion of safety laser radar and multiple sensors at the input level, and also adopts redundant design. It adopts the combination of safety PLC+AGV master control at the decision-making level (the safety PLC layer serves as the main decision-making center), and adopts multiple flexible laser obstacle avoidance area switching strategies and safe AGV motion control (deceleration or power-off braking) at the output level. It also adopts redundant design, and the overall system design has high safety. In actual application, by matching corresponding laser obstacle avoidance areas according to different speed ranges, distinguishing the presence or absence of goods, and the laser obstacle avoidance areas during the picking and releasing process, it can adapt to the requirements of extremely small channels, intelligent identification equipment docking, and intelligent identification charging piles for automatic charging. According to the above-mentioned trigger conditions, the combination of laser obstacle avoidance area switching trigger conditions is reasonable. According to the operating characteristics of the AGV car, different sensors and other signals are combined for matrix management to match different laser obstacle avoidance areas to meet the scene condition requirements of the AGV car in different operating environments and different working conditions.

[0042] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiment. All technical solutions based on the concept of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. An AGV laser obstacle avoidance method based on safety PLC control, characterized in that: include: Step S1: The AGV master control machine controls the AGV to move according to the scene requirements; Step S2: The safety PLC control layer generates a corresponding laser obstacle avoidance area switching instruction based on the AGV's location, the AGV's travel speed, and the AGV's cargo status. Step S3: The safety PLC control layer controls and adjusts the detection area of ​​the safety laser radar based on the generated laser obstacle avoidance area switching instruction; Step S4: When the safety laser radar detects an obstacle in the detection area, it transmits a signal to the safety PLC control layer to execute corresponding countermeasures.

2. The AGV laser obstacle avoidance method based on safety PLC control according to claim 1 is characterized in that: The area where the AGV car is located in step S2 includes a normal moving area, a pick-up and placement area, and a complex area; according to the different working areas where the AGV car is located, the safety PLC control layer generates a corresponding first judgment signal.

3. The AGV laser obstacle avoidance method based on safety PLC control according to claim 1 is characterized in that: The traveling speed of the AGV in step S2 includes several set speed intervals; according to the different speed intervals of the AGV, the safety PLC control layer generates a corresponding second judgment signal.

4. The AGV laser obstacle avoidance method based on safety PLC control according to claim 1 is characterized in that: The cargo consignment status of the AGV in step S2 includes a no-cargo status, a small pallet consignment status, and a large pallet consignment status; according to the cargo holding status of the AGV, the safety PLC control layer generates a corresponding third judgment signal.

5. The AGV laser obstacle avoidance method based on safety PLC control according to any one of claims 1 to 4, characterized in that: The safety PLC control layer in step S2 outputs corresponding laser obstacle avoidance area switching instructions according to different judgment signal combinations, including: increasing the detection area of ​​the safety laser radar, reducing the detection area of ​​the safety laser radar, turning off the safety laser radar, or turning on the safety laser radar.

6. The AGV laser obstacle avoidance method based on safety PLC control according to claim 5 is characterized in that: The AGV master computer in step S3 is bidirectionally connected to the safety PLC layer via CAN communication, and is used to receive the transmitted laser obstacle avoidance area switching instruction, and control and adjust the detection area of ​​the safety laser radar according to the laser obstacle avoidance area switching instruction.

7. The AGV laser obstacle avoidance method based on safety PLC control according to claim 1 is characterized in that: The detection area of ​​the safety laser radar includes the deceleration area and the parking area.

8. The AGV laser obstacle avoidance method based on safety PLC control according to claim 7 is characterized in that: In step S4, when the safety laser radar identifies an obstacle in the deceleration zone within the detection area, it transmits a signal to the safety PLC layer, and the safety PLC layer transmits a deceleration control instruction to the AGV main control machine to execute the deceleration of the AGV vehicle drive wheel; When the safety laser radar identifies an obstacle in the parking area within the detection area, it transmits a signal to the safety PLC layer, which executes the motor power-off brake command to stop the AGV.

9. The AGV laser obstacle avoidance method based on safety PLC control according to claim 1 is characterized in that: The step S2 also includes: the AGV main control machine detects the status of the AGV vehicle and executes the laser obstacle avoidance area active switching instruction according to the working status of the AGV vehicle; the laser obstacle avoidance area active switching instruction includes: reducing the detection area of ​​the safety laser radar and turning off the safety laser radar.

10. The AGV laser obstacle avoidance method based on safety PLC control according to claim 9 is characterized in that: The working status of the AGV includes: normal consignment working status, AGV charging status and AGV equipment docking status.

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