An automatic following control method and system for picking carts based on joint positioning

Abstract

This invention discloses an automatic following control method for picking carts based on joint positioning, comprising: activating the following function of the picking cart and setting a following area; performing joint positioning of the following object using a UWB positioning module and a lidar module; executing automatic following operation when the following object is within the following area; stopping following when the following object leaves the following area; using a lidar module and an ultrasonic module to detect obstacles in the direction of travel and executing corresponding obstacle avoidance measures according to preset control commands; and also disclosing an automatic following control system for picking carts using this method. This invention employs a combination of UWB positioning technology and lidar positioning technology, using UWB positioning technology for initial positioning of the following object and lidar positioning technology for auxiliary positioning to determine the effectiveness of the UWB positioning technology, thereby achieving precise positioning of the following object.

Description

Technical Field

[0001] This invention relates to the field of picking cart technology, and in particular to an automatic following control method and system for picking carts based on joint positioning. Background Technology

[0002] In warehouse management, picking carts play a crucial role in handling and sorting. However, most current warehouse operations rely on operators to move goods from the starting point to the destination using picking carts. This requires operators to frequently get on and off the carts, driving them to different points for loading and unloading. This not only drains the operators' mental energy but also hinders warehouse efficiency. To address this issue, automated following picking carts have emerged. Existing automated following picking carts use wireless ranging sensors to detect the distance between the cart and the object being followed, or employ UWB technology to locate the object, before performing the following operation. However, warehouse environments often contain numerous shelves and other items that obstruct or block the wireless positioning information, causing it to drift or become obstructed, compromising the accuracy of the picking cart's location when automatically following the object.

[0003] The Chinese patent document "A Method and System for Automatic Vehicle Following Based on UWB Technology," publication number CN114889594A, published on August 12, 2022, includes the following steps: A user activates the automatic vehicle following function; the vehicle detects the road conditions based on a high-precision map and determines that the road is not a highway; the vehicle then uses multiple sensors to detect the surrounding environment in real time and determines that there are no obstacles obstructing its passage; it then uses UWB technology to detect the distance between the vehicle and the user in real time, and if the distance is within a set following distance range, it plans a driving path to follow the user; the vehicle then follows the driving path and approaches the user until the distance between the vehicle and the user is less than the minimum following distance, at which point the vehicle stops; when the distance between the vehicle and the user is again within the set following distance range, the above steps are repeated, and this cycle continues until the user deactivates the automatic following function. This technology uses UWB technology for vehicle and object positioning. However, when applied to a warehouse environment, it also suffers from the problem of wireless positioning information drifting or being obstructed by numerous shelves and items, making it impossible to guarantee the accuracy of object positioning when a picking vehicle automatically follows within the warehouse. Summary of the Invention

[0004] This invention aims to overcome the problem in existing technologies where wireless positioning suffers from information drift and inaccurate positioning of the following object in warehouse environments with numerous shelves and items obstructing the view. It provides an automatic following control method and system for picking carts based on joint positioning. This method combines UWB positioning technology and LiDAR positioning technology. UWB positioning technology is used for initial positioning of the following object, while LiDAR positioning technology is used for auxiliary positioning to determine the effectiveness of UWB positioning, thereby achieving precise positioning of the following object.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] An automatic following control method for picking carts based on joint positioning includes:

[0007] Activate the following function of the picking vehicle and set the following area;

[0008] The UWB positioning module and the LiDAR module are used to jointly locate the target object. When the target object is within the tracking area, the automatic tracking operation is performed; when the target object leaves the tracking area, the tracking stops.

[0009] The system uses a lidar module and an ultrasonic module to detect obstacles in the direction of travel and executes corresponding obstacle avoidance measures according to preset control commands.

[0010] This invention combines UWB positioning technology and LiDAR positioning technology to determine the location of the object being followed. This overcomes the problem of inaccurate positioning information drift caused by the large number of shelves and items obstructing the view in the warehouse environment when using UWB positioning technology alone. The high precision of LiDAR makes the positioning more accurate. In addition, using LiDAR in conjunction with ultrasonic radar to detect obstacles in the direction of the picking vehicle's movement provides high sensitivity, strong long-distance detection capability, and can cover a large obstacle detection range, which can improve the stability and accuracy of the following system and achieve more effective obstacle avoidance and following.

[0011] Preferably, the process of setting the following region includes:

[0012] Select several fixed points on the picking cart as following points, and set a corresponding following distance threshold for each following point; set a certain width range on both sides of the picking cart as the initial area, and the part of the initial area from which the distance to the following point is greater than or equal to its corresponding following distance threshold is the following area of ​​that following point;

[0013] The following area is switched by switching the following point.

[0014] In this invention, the following area setting allows the picking vehicle to follow only when the object being followed is within the following area; if the object is outside the following area, the picking vehicle will not follow. Multiple following areas can be pre-set, and the appropriate following area can be selected for the picking vehicle's following operation as needed. The following function of the picking vehicle can be activated via buttons on the vehicle body or the remote control unit in the UWB positioning module.

[0015] Preferably, the line connecting the wireless base station of the UWB positioning module and the lidar of the lidar module is parallel to the length direction of the picking cart, and the joint positioning process includes:

[0016] The target object is located to obtain its azimuth angle and following distance (θ) relative to the lidar. l ,L l ) and the azimuth and following distance relative to the wireless base station (θ) b ,L b ); The azimuth angle is the offset angle based on the width direction of the picking cart;

[0017] Based on the azimuth angle and following distance, distance projection is performed in the width direction of the picking vehicle. When the difference between the distance projection of the lidar and the wireless base station is within the preset error range, the joint positioning is effective and the positioning is completed.

[0018] In this invention, since the line connecting the lidar and the wireless base station is parallel to the length direction of the picking cart and perpendicular to the width direction, the lidar, the wireless base station, and the object being followed can be considered as the three vertices of a triangle. The azimuth angle of the object being followed relative to the lidar is the angle between the line connecting the object and the lidar and the width direction of the picking cart. Similarly, the azimuth angle of the object being followed relative to the wireless base station can be obtained. Under ideal and precise conditions, the projection length of the following distance in the width direction of the picking cart is exactly the height of the triangle with the line connecting the lidar and the wireless base station as its base. Therefore, this is used as a standard to compare the distance projection difference between the lidar and the wireless base station to determine whether the positioning is effective. The preset error range is determined by the actual required positioning accuracy. If the positioning is invalid, the positioning is re-performed. If the positioning is still invalid after multiple repetitions, the following stops.

[0019] Preferably, the lidar module's positioning process for the target object includes:

[0020] Obtain distance data for all laser points within the tracking area;

[0021] All laser points are clustered according to a preset threshold for the distance difference between adjacent laser points to obtain several laser lines;

[0022] Based on the geometric parameters of the object being followed and the following distance, filter conditions are set to obtain several laser lines that meet the filter conditions; the difference between the maximum and minimum following distances of the laser points in the laser lines is calculated, and laser lines whose differences are within the preset difference threshold range are selected, with the following distance and azimuth of the central laser point of the laser line as the positioning data.

[0023] In this invention, the data obtained by the lidar can be programmed in an industrial control computer. In addition to clustering the lidar data, corresponding filtering conditions are set to delete the lidar lines that are not the objects being followed, leaving the lidar lines that represent the objects being followed, thereby determining the position of the lidar relative to the objects being followed. Then, the position of the objects being followed is determined by combining UWB positioning and lidar positioning, resulting in higher accuracy and a more stable system.

[0024] Preferably, the screening criteria are:

[0025] The angle range Δθ occupied by the width parameter range of the following object is obtained by using the sector arc length formula l=Δθ×R, where l represents the width parameter range of the following object and R represents the following distance;

[0026] The angle between the two endpoints of the laser line and the line connecting the laser radar is taken as the angle of the laser line, and a laser line that fits the angle range Δθ is selected.

[0027] In this invention, the two ends of the width of the following object can be approximated as the two ends of an arc centered on the LiDAR. Therefore, the central angle of the following object relative to the LiDAR can be obtained using the sector arc length formula. After setting the width parameter of the following object in advance, the angle range corresponding to the following object can be directly obtained according to the following distance. Based on this, all laser lines that meet the requirements can be screened out, which can improve the speed of positioning processing and improve the accuracy of following object recognition and positioning.

[0028] Preferably, after completing joint positioning, the azimuth angle and following distance (θ) of the target object relative to the wireless base station are used as the basis for positioning. b ,L b ) as positioning parameters;

[0029] Using the distance from the following point to the wireless base station, the following distance, and the azimuth angle as the two sides and the included angle of a triangle, the distance from the following object to the following point is obtained through the law of cosines. This distance is then compared with the following distance threshold to determine whether the following object is within the following area.

[0030] In this invention, once the object being followed leaves the following area, the following function immediately enters a dormant state, and the picking vehicle does not follow it. When the object returns to the following area within a set time, the following function is immediately awakened from the dormant state, and the picking vehicle moves along with the object. If the object does not return to the following area within the set time, for safety reasons, the following function is automatically turned off, and the following operation indicator light goes out. At this time, after the object returns to the following area, the following function can be restarted or not restarted as needed.

[0031] Preferably, the lidar module and the ultrasonic module detect obstacles in the direction of the picking vehicle's movement, and the obstacle detection area of ​​the lidar module is set.

[0032] When the ultrasonic module detects an obstacle, it performs a stop operation and then follows the object to detour around it.

[0033] When an obstacle is detected within the obstacle detection area of ​​the lidar module but outside the detection range of the ultrasonic module, a speed limit operation is performed.

[0034] In this invention, the laser radar has a large scanning detection range. It can extract a fan-shaped obstacle detection area with the required detection angle and distance according to actual needs. The angle and distance corresponding to the effective laser points in this fan-shaped area are considered as the detection angle and distance of the obstacle. The ultrasonic radar has a smaller detection distance, so there is no restriction on the obstacle detection area. Any object that can be detected within its own detection range is considered as an obstacle. Once an obstacle is detected in the forward direction of the picking vehicle, the control module will first light up the obstacle indicator light to remind the user.

[0035] An automated following control system for picking carts based on joint positioning includes:

[0036] UWB positioning module, used to locate the following object, includes a wireless base station set on the picking cart, a matching unit and a remote control unit carried by the following object;

[0037] A lidar module, including lidar for locating objects and obstacles;

[0038] An ultrasonic module, including ultrasonic radar for detecting and locating obstacles;

[0039] The control module is used to control the operation of the entire automatic following control system.

[0040] In this invention, the UWB positioning module and the LiDAR module locate the object being followed, while the LiDAR module and the ultrasonic module detect obstacles. The control module includes control for the follow-up start-up, follow-up operation and positioning, obstacle indicator light control, and picking cart operation control. This automatic follow-up control system can be modified and added to existing picking carts. Operators can choose whether to enable the follow-up function according to their own wishes. As long as the follow-up function is enabled, the operator only needs to walk to the shelf where the goods to be loaded or unloaded, and the picking cart will automatically follow the operator. If the two target shelves are far apart, the operator can disable the follow-up function at any time and drive the picking cart to the next shelf, making the control of the picking cart more flexible.

[0041] Preferably, a joint positioning component is symmetrically arranged on both sides of the picking cart. The joint positioning component includes a lidar and a wireless base station arranged at a certain distance, and the line connecting the lidar and the wireless base station is parallel to the length direction of the picking cart.

[0042] A third lidar for detecting obstacles is fixed below the front of the picking vehicle, and an ultrasonic radar is installed above the front of the picking vehicle and above the third lidar.

[0043] In this invention, the positions of each component of the lidar module, each component of the UWB positioning module, and the component of the ultrasonic module are set accordingly. The position combination of the lidar and the wireless base station used for object following is beneficial to the analysis of positioning data and improves positioning accuracy. The position combination of the lidar and the ultrasonic radar used for obstacle detection can increase the obstacle detection coverage in the forward direction of the picking vehicle and ensure the stability of automatic following.

[0044] This invention has the following advantages: It combines UWB positioning technology and LiDAR positioning technology. UWB positioning technology is used for initial positioning of the object being followed, and LiDAR positioning technology is used for auxiliary positioning to determine the effectiveness of UWB positioning, thus achieving precise positioning of the object. In LiDAR positioning technology, laser point data is not only clustered, but also filtered according to corresponding conditions to select laser lines that match the object being followed, assisting UWB positioning technology to achieve higher positioning accuracy. The picking vehicle only performs the following operation according to the object being followed, without a prescribed following route, resulting in greater freedom and flexibility, which better suits the randomness of picking goods in a warehouse. Attached Figure Description

[0045] Figure 1 This is a flowchart of the automatic following control method of the present invention;

[0046] Figure 2 This is a schematic diagram of the following region in an embodiment of the present invention;

[0047] Figure 3 This is a schematic diagram of joint positioning in an embodiment of the present invention;

[0048] Figure 4 This is a schematic diagram of the obstacle detection range in an embodiment of the present invention. Detailed Implementation

[0049] The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0050] like Figure 1 As shown, an automatic following control method for picking carts based on joint positioning includes:

[0051] Activate the following function of the picking vehicle and set the following area; the process of setting the following area includes:

[0052] Select several fixed points on the picking cart as following points, and set a corresponding following distance threshold for each following point; set a certain width range on both sides of the picking cart as the initial area, and the part of the initial area from which the distance to the following point is greater than or equal to its corresponding following distance threshold is the following area of ​​that following point;

[0053] The following area is switched by switching the following point.

[0054] The UWB positioning module and the LiDAR module are used to jointly locate the object being followed. When the object is within the following area, the automatic following operation is performed; when the object leaves the following area, the following stops.

[0055] The connection between the wireless base station of the UWB positioning module and the lidar of the lidar module is parallel to the length direction of the picking cart. The joint positioning process includes:

[0056] The target object is located to obtain its azimuth angle and following distance (θ) relative to the lidar. l ,L l ) and the azimuth and following distance relative to the wireless base station (θ) b ,L b ); The azimuth angle is the offset angle based on the width direction of the picking cart;

[0057] Based on the azimuth angle and following distance, distance projection is performed in the width direction of the picking vehicle. When the difference between the distance projection of the lidar and the wireless base station is within the preset error range, the joint positioning is effective and the positioning is completed.

[0058] The process of locating the target object by the lidar module includes:

[0059] Obtain distance data for all laser points within the tracking area;

[0060] All laser points are clustered according to a preset threshold for the distance difference between adjacent laser points to obtain several laser lines;

[0061] Based on the geometric parameters of the object being followed and the following distance, filter conditions are set to obtain several laser lines that meet the filter conditions; the difference between the maximum and minimum following distances of the laser points in the laser lines is calculated, and laser lines whose differences are within the preset difference threshold range are selected, with the following distance and azimuth of the central laser point of the laser line as the positioning data.

[0062] The filtering criteria are:

[0063] The angle range Δθ occupied by the width parameter range of the following object is obtained by using the sector arc length formula l=Δθ×R, where l represents the width parameter range of the following object and R represents the following distance;

[0064] The angle between the two endpoints of the laser line and the line connecting the laser radar is taken as the angle of the laser line, and a laser line that fits the angle range Δθ is selected.

[0065] After joint positioning is completed, the azimuth angle and following distance (θ) of the followed object relative to the wireless base station are used. b ,L b ) as positioning parameters;

[0066] Using the distance from the following point to the wireless base station, the following distance, and the azimuth angle as the two sides and the included angle of a triangle, the distance from the following object to the following point is obtained through the law of cosines. This distance is then compared with the following distance threshold to determine whether the following object is within the following area.

[0067] The system uses a lidar module and an ultrasonic module to detect obstacles in the direction of travel and executes corresponding obstacle avoidance measures according to preset control commands.

[0068] The lidar module and ultrasonic module detect obstacles in the direction the picking cart is moving, and the obstacle detection area of ​​the lidar module is set.

[0069] When the ultrasonic module detects an obstacle, it performs a stop operation and then follows the object to detour around it.

[0070] When an obstacle is detected within the obstacle detection area of ​​the lidar module but outside the detection range of the ultrasonic module, a speed limit operation is performed.

[0071] This invention combines UWB positioning technology and LiDAR positioning technology to determine the location of the object being followed. This overcomes the problem of inaccurate positioning information drift caused by the large number of shelves and items obstructing the view in the warehouse environment when using UWB positioning technology alone. The high precision of LiDAR makes the positioning more accurate. In addition, using LiDAR in conjunction with ultrasonic radar to detect obstacles in the direction of the picking vehicle's movement provides high sensitivity, strong long-distance detection capability, and can cover a large obstacle detection range, which can improve the stability and accuracy of the following system and achieve more effective obstacle avoidance and following.

[0072] In this invention, the following area setting allows the picking vehicle to follow only when the object being followed is within the following area; if the object is outside the following area, the picking vehicle will not follow. Multiple following areas can be pre-set, and the appropriate following area can be selected for the picking vehicle's following operation as needed. The following function of the picking vehicle can be activated via buttons on the vehicle body or the remote control unit in the UWB positioning module.

[0073] In this invention, since the line connecting the lidar and the wireless base station is parallel to the length direction of the picking cart and perpendicular to the width direction, the lidar, the wireless base station, and the object being followed can be considered as the three vertices of a triangle. The azimuth angle of the object being followed relative to the lidar is the angle between the line connecting the object and the lidar and the width direction of the picking cart. Similarly, the azimuth angle of the object being followed relative to the wireless base station can be obtained. Under ideal and precise conditions, the projection length of the following distance in the width direction of the picking cart is exactly the height of the triangle with the line connecting the lidar and the wireless base station as its base. Therefore, this is used as a standard to compare the distance projection difference between the lidar and the wireless base station to determine whether the positioning is effective. The preset error range is determined by the actual required positioning accuracy. If the positioning is invalid, the positioning is re-performed. If the positioning is still invalid after multiple repetitions, the following stops.

[0074] In this invention, the data obtained by the lidar can be programmed in an industrial control computer. In addition to clustering the lidar data, corresponding filtering conditions are set to delete the lidar lines that are not the objects being followed, leaving the lidar lines that represent the objects being followed, thereby determining the position of the lidar relative to the objects being followed. Then, the position of the objects being followed is determined by combining UWB positioning and lidar positioning, resulting in higher accuracy and a more stable system.

[0075] In this invention, the two ends of the width of the following object can be approximated as the two ends of an arc centered on the LiDAR. Therefore, the central angle of the following object relative to the LiDAR can be obtained using the sector arc length formula. After setting the width parameter of the following object in advance, the angle range corresponding to the following object can be directly obtained according to the following distance. Based on this, all laser lines that meet the requirements can be screened out, which can improve the speed of positioning processing and improve the accuracy of following object recognition and positioning.

[0076] In this invention, once the object being followed leaves the following area, the following function immediately enters a dormant state, and the picking vehicle does not follow it. When the object returns to the following area within a set time, the following function is immediately awakened from the dormant state, and the picking vehicle moves along with the object. If the object does not return to the following area within the set time, for safety reasons, the following function is automatically turned off, and the following operation indicator light goes out. At this time, after the object returns to the following area, the following function can be restarted or not restarted as needed.

[0077] In this invention, the laser radar has a large scanning detection range. It can extract a fan-shaped obstacle detection area with the required detection angle and distance according to actual needs. The angle and distance corresponding to the effective laser points in this fan-shaped area are considered as the detection angle and distance of the obstacle. The ultrasonic radar has a smaller detection distance, so there is no restriction on the obstacle detection area. Any object that can be detected within its own detection range is considered as an obstacle. Once an obstacle is detected in the forward direction of the picking vehicle, the control module will first light up the obstacle indicator light to remind the user.

[0078] An automated following control system for picking carts based on joint positioning includes:

[0079] UWB positioning module, used to locate the following object, includes a wireless base station set on the picking cart, a matching unit and a remote control unit carried by the following object;

[0080] A lidar module, including lidar for locating objects and obstacles;

[0081] An ultrasonic module, including ultrasonic radar for detecting and locating obstacles;

[0082] The control module is used to control the operation of the entire automatic following control system.

[0083] A joint positioning component is symmetrically arranged on both sides of the picking cart. The joint positioning component includes a lidar and a wireless base station set at a certain distance. The line connecting the lidar and the wireless base station is parallel to the length direction of the picking cart.

[0084] A third lidar for detecting obstacles is fixed below the front of the picking vehicle, and an ultrasonic radar is installed above the front of the picking vehicle and above the third lidar.

[0085] In this invention, the UWB positioning module and the LiDAR module locate the object being followed, while the LiDAR module and the ultrasonic module detect obstacles. The control module includes control for the follow-up start-up, follow-up operation and positioning, obstacle indicator light control, and picking cart operation control. This automatic follow-up control system can be modified and added to existing picking carts. Operators can choose whether to enable the follow-up function according to their own wishes. As long as the follow-up function is enabled, the operator only needs to walk to the shelf where the goods to be loaded or unloaded, and the picking cart will automatically follow the operator. If the two target shelves are far apart, the operator can disable the follow-up function at any time and drive the picking cart to the next shelf, making the control of the picking cart more flexible.

[0086] In this invention, the positions of each component of the lidar module, each component of the UWB positioning module, and the component of the ultrasonic module are set accordingly. The position combination of the lidar and the wireless base station used for object following is beneficial to the analysis of positioning data and improves positioning accuracy. The position combination of the lidar and the ultrasonic radar used for obstacle detection can increase the obstacle detection coverage in the forward direction of the picking vehicle and ensure the stability of automatic following.

[0087] In the embodiments of the present invention, the following will be described in sequence according to the three aspects of the picking vehicle’s follow-up start, follow-up object positioning and obstacle detection. In this embodiment, the follow-up object is the operator and the matching unit is the NFC unit; there are a total of three lidars, two wireless base stations and two ultrasonic radars.

[0088] Follow the startup section:

[0089] Both the picking cart and the remote control unit are equipped with a follow function switch button. Operators can choose one of these methods to activate or deactivate the vehicle's follow function based on their situation. The two switches are interoperable; activating the follow function using the vehicle's switch button allows deactivation using either the vehicle's switch button or the button on the remote control unit, and vice versa. When the follow function is activated, the operator brings their remote control unit close to or places it on the NFC unit on the picking cart to swipe a card and match the vehicle with the UWB positioning unit (remote control unit + wireless base station), ensuring that each vehicle follows only one remote control unit (operator).

[0090] The conditions for following the picking cart include:

[0091] Condition 1: The operator must be in accordance with... Figure 2The following function can only operate normally within the indicated following area; otherwise, even if the following function is enabled, the picking vehicle will only be in a dormant state.

[0092] Condition 2: If Figure 2 The pallet positions A, B, and C shown are the selectable following points for the picking cart by the operator. The shaded area in the diagram represents the initial region, the width of which can be set according to actual conditions. Taking pallet position A as the following point as an example, when the operator is within the following area and the distance from pallet position A is greater than or equal to the set following distance threshold, the picking cart will follow the operator. However, when the distance between the operator and pallet position A is less than the set following distance threshold, the following function is in a dormant state. This situation typically occurs when the operator is stationed in front of a storage rack, loading, unloading, or sorting goods. The distance between pallet position A and the operator is related to the operator's positioning data, θ in the diagram. b It is the operator's azimuth angle relative to the wireless base station. Given the following distance from the wireless base station to the operator, the distance from the wireless base station to tray position A, and the azimuth angle, the distance from the operator to tray position A can be calculated using the law of cosines.

[0093] Condition 3: Once the operator leaves the following area, the following function immediately goes into dormancy and the picking cart does not follow. Once the operator returns to the following area within the set time, the following function is immediately awakened from dormancy and the picking cart moves with the operator. If the operator does not return to the following area within the set time, the following function will automatically shut down for safety reasons and the following operation indicator light will turn off. At this time, the operator can restart the following function as desired after returning to the following area.

[0094] Following object positioning section:

[0095] The UWB positioning module locates the operator. After the follow function is activated, the remote control unit on the operator transmits a signal, and the wireless base station on the picking vehicle receives the signal transmitted by the remote control unit. The operator's (remote control unit's) azimuth and distance relative to the wireless base station can be obtained, which is the operator's positioning information.

[0096] The LiDAR module is used for operator positioning. UWB uses AOA positioning technology. However, there are many obstructions from the shelves in the warehouse, which can cause the wireless positioning information to drift. To ensure the accuracy of the position signal, LiDAR is used to assist in the positioning of the operator.

[0097] (1) Laser data preprocessing: First, obtain the distance data of all laser points of the lidar, then remove laser points outside the following distance and azimuth range, and retain the distance data of laser points within the following area.

[0098] (2) Clustering of laser points: A threshold for the distance difference between adjacent laser points is set. Starting from the first laser point corresponding to the smallest angle, laser points whose distance difference is within the threshold range are grouped into one category. Since a single-line lidar is used for scanning, several laser lines composed of laser points can be seen.

[0099] (3) Set the range of operator body width parameters. Use the fan arc length formula l=Δθ×R, where arc length l represents the operator's body width and R represents the following distance. This gives the angle Δθ of the line representing the operator's body width. Based on the range of body width parameters, the range of the current operator's angle Δθ can be obtained. Remove the laser lines that are not within the obtained angle range from the above clustering and leave the laser lines that are within the angle range of the operator's body width.

[0100] (4) Based on the characteristics of the operator's laser line, the remaining laser lines are filtered to determine the final positioning azimuth and following distance of the operator. The operator's laser line is an arc that is close to a semicircle. The distance data corresponding to the two ends of the arc is not much different. The maximum and minimum distances between the laser point in the arc and the lidar are quite different. Based on this characteristic, the distance difference threshold is set according to the actual size of the operator to determine the laser line representing the operator. Finally, the distance and azimuth of the laser point located in the center of the laser line to the lidar are used as the positioning data information of the lidar for the operator.

[0101] In joint positioning, the operator's location obtained by UWB and the operator's location obtained by LiDAR are respectively the azimuth and distance relative to the wireless base station and the LiDAR. A schematic diagram of its joint positioning is shown below. Figure 3 As shown, the wireless base station positioning data is represented as (θ) b ,L b The lidar positioning data is represented as (θ). l ,L l ).Depend on Figure 3 It can be seen that the wireless base station lines on both sides of the vehicle body are parallel to the lidar lines, and their positive directions are consistent. The wireless base station locates the remote control unit in the operator's hand or pocket, while the lidar locates the operator himself. Since UWB wireless base station positioning lacks spatial vertical distance information, only planar offset azimuth angle, and lidar positioning is similar, it is approximately assumed that the remote control unit, lidar, and wireless base station are coplanar. The tracking distance data is projected onto the remote control unit based on its respective azimuth angle. and If the difference between these two projections is within the preset error range, then the UWB positioning is considered valid, and L will be... b As the operator's following distance, θ b As the direction angle.

[0102] The UWB positioning module inputs the operator's positioning information to the control module via a serial port, while the LiDAR inputs the operator's positioning information to the control module via an industrial computer. The control module then performs joint positioning. If the positioning is valid, the control module sends a speed command to the motor controller of the picking cart, controlling the motor to rotate at a certain speed so that the picking cart follows the operator's movement. Otherwise, the control module does not issue a command, the motor speed is zero, the picking cart does not move, and the follow indicator light flashes, indicating a follow-up error.

[0103] Obstacle detection section:

[0104] like Figure 4 The diagram shows obstacle detection in the forward direction of the picking cart. The lidar is installed below the cart's forward direction. Because it's a single-line lidar, its obstacle detection area is a laser scanning plane perpendicular to the forward direction. The detection space in the vertical direction is limited, so it's paired with two ultrasonic radars to form an obstacle detection system. There are two ultrasonic radars: one installed above the front of the picking cart, and the other installed in the lower middle part of the front, above the lidar. The detection area is as shown... Figure 4 As shown, the ultrasonic detection area and the laser detection area together cover the obstacle detection area in the direction of the picking vehicle's movement.

[0105] (1) The laser radar used for obstacle detection has a scanning angle range of [-180°, 180°] and a maximum detection distance of 50 meters. Based on actual needs, a fan-shaped obstacle detection area with the required detection angle and distance is selected. The angle and distance corresponding to the effective laser points within this fan-shaped area are considered as the detection angle and distance of the obstacle.

[0106] (2) The maximum range of ultrasonic obstacle detection is 5 meters, so there is no restriction on the obstacle detection area. Any object that can be detected within its own detection range is considered an obstacle.

[0107] Once an obstacle is detected in the direction the picking vehicle is moving forward, the control module first illuminates the obstacle indicator light. Secondly, based on the obstacle detection distance, it controls the motor speed to either limit the speed or stop the vehicle. If the obstacle is within the ultrasonic detection range (i.e., when the ultrasonic module detects the obstacle), it stops and then follows the object around it. If the obstacle detection distance is greater than the ultrasonic detection distance but less than the laser detection distance, it limits the speed.

[0108] The above embodiments are further elaborations and descriptions of the present invention to facilitate understanding, and are not intended to limit the present invention in any way. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for automatic following control of picking carts based on joint positioning, characterized in that, include: Activate the following function of the picking vehicle and set the following area; The process of setting the following region includes: Select several fixed points on the picking cart as following points, and set a corresponding following distance threshold for each following point; The initial area is defined as a certain width range on both sides of the picking cart. The part of the initial area whose distance to the following point is greater than or equal to its corresponding following distance threshold is the following area of ​​that following point. The following area is switched by switching the following point; The UWB positioning module and the LiDAR module are used to jointly locate the target object. When the target object is within the tracking area, the automatic tracking operation is performed; when the target object leaves the tracking area, the tracking stops. The system uses a lidar module and an ultrasonic module to detect obstacles in the direction of travel and executes corresponding obstacle avoidance measures according to preset control commands.

2. The automatic following control method for picking carts based on joint positioning according to claim 1, characterized in that, The connection between the wireless base station of the UWB positioning module and the lidar of the lidar module is parallel to the length direction of the picking cart. The joint positioning process includes: The target object is located to obtain its azimuth and tracking distance relative to the lidar. and azimuth and following distance relative to the wireless base station The azimuth angle is the offset angle based on the width direction of the picking cart. Based on the azimuth angle and following distance, distance projection is performed in the width direction of the picking vehicle. When the difference between the distance projection of the lidar and the wireless base station is within the preset error range, the joint positioning is effective and the positioning is completed.

3. The automatic following control method for picking carts based on joint positioning according to claim 2, characterized in that, The process of locating the target object by the lidar module includes: Obtain distance data for all laser points within the tracking area; All laser points are clustered according to a preset threshold for the distance difference between adjacent laser points to obtain several laser lines; Based on the geometric parameters of the object being followed and the following distance, filter conditions are set to obtain several laser lines that meet the filter conditions; Calculate the difference between the maximum and minimum following distances of the laser points in the laser line, select laser lines whose differences are within a preset difference threshold range, and use the following distance and azimuth of the central laser point of the laser line as positioning data.

4. The automatic following control method for picking carts based on joint positioning according to claim 3, characterized in that, The filtering criteria are as follows: Using the sector arc length formula ,in This represents the range of the width parameter of the following object. This represents the following distance, and gives the angular range occupied by the width parameter range of the following object. ; The angle of the laser line is defined by the angle between the two endpoints of the laser line and the line connecting the laser radar, and a suitable angle range is selected. Laser lines.

5. The automatic following control method for picking carts based on joint positioning according to claim 2, characterized in that, After joint positioning is completed, the azimuth and following distance of the target object relative to the wireless base station are used. As a positioning parameter; Using the distance from the following point to the wireless base station, the following distance, and the azimuth angle as the two sides and the included angle of a triangle, the distance from the following object to the following point is obtained through the law of cosines. This distance is then compared with the following distance threshold to determine whether the following object is within the following area.

6. A method for automatic following control of a picking cart based on joint positioning according to claim 1, 3, 4, or 5, characterized in that, The lidar module and ultrasonic module detect obstacles in the direction the picking cart is moving, and the obstacle detection area of ​​the lidar module is set. When the ultrasonic module detects an obstacle, it performs a stop operation and then follows the object to detour around it. When an obstacle is detected within the obstacle detection area of ​​the lidar module but outside the detection range of the ultrasonic module, a speed limit operation is performed.

7. An automatic following control system for picking carts based on joint positioning, employing the automatic following control method for picking carts as described in any one of claims 1-6, characterized in that, include: UWB positioning module, used to locate the following object, includes a wireless base station set on the picking cart, a matching unit and a remote control unit carried by the following object; A lidar module, including lidar for locating objects and obstacles; An ultrasonic module, including ultrasonic radar for detecting and locating obstacles; The control module is used to control the operation of the entire automatic following control system.

8. The automatic following control system for picking carts based on joint positioning according to claim 7, characterized in that, A joint positioning component is symmetrically arranged on both sides of the picking cart. The joint positioning component includes a lidar and a wireless base station arranged at a certain distance. The line connecting the lidar and the wireless base station is parallel to the length direction of the picking cart. A third lidar for detecting obstacles is fixed below the front of the picking vehicle, and an ultrasonic radar is installed above the front of the picking vehicle and above the third lidar.

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