Sliding-mode control method for robot palletizer

Abstract

The invention discloses a sliding mode control method for a stacking robot, which comprises the following steps: acquiring the pose information of bricks in a brick stack under a coordinate system of the stacking robot through a sensing unit arranged on the stacking robot; according to the kinematic model of the palletizing robot, the current pose of the palletizing robot under the world coordinate system is determined; according to the pose information of the bricks under the coordinate system of the stacking robot and the current pose of the stacking robot under the world coordinate system, the expected pose of the stacking robot under the world coordinate system is determined; according to the current pose and the expected pose of the palletizing robot under the world coordinate system, the pose error of the palletizing robot is determined; according to the pose error, sliding mode control is conducted on the current pose of the stacking robot under the world coordinate system till the pose error is smaller than a set threshold value; and the palletizing robot is controlled to move in the set direction till the pose information of the bricks in the coordinate system of the palletizing robot meets the set requirement. The method is high in control precision and good in robustness.

Description

Technical Field

[0001] The invention relates to the technical field of mobile robot control, and in particular to a sliding mode control method of a palletizing robot. Background Art

[0002] The development of mobile brick-moving robots stems from the continuous pursuit of automation and efficiency in the construction industry. Traditional brick handling is usually done manually, which is not only time-consuming and labor-intensive, but also has safety hazards. Therefore, it is of great significance to introduce robot technology to complete the task of brick handling, and how to achieve effective control of mobile robots is a major problem at present.

[0003] Most of the existing mobile robot control methods use traditional control methods, such as PID control, state space control, adaptive control, etc. 1) PID control is proportional-integral-differential control. Proportional control is used to reduce the current error, integral control is used to eliminate steady-state error, and differential control is used to predict the error change trend. It has a simple structure but has poor effects on nonlinear systems and time-varying systems. It is difficult to adjust parameters and cannot handle complex systems. 2) State space control uses matrices and vectors to describe the dynamic behavior of the system through state space representation. Although it is more flexible, it requires an accurate mathematical model of the system. When the model is inaccurate, the performance decreases. The design is complex and the calculation complexity is high. 3) Adaptive control can automatically adjust the control parameters according to the real-time state and performance of the system to cope with changes in system parameters and environmental changes, but it requires complex algorithms and real-time computing capabilities, has high real-time requirements for the system, and requires rapid response and adjustment of control parameters. It is not suitable for the control of palletizing robots.

[0004] Sliding mode control has strong robustness, can effectively cope with system parameter changes and external interference, and achieve fast response and stable operation. Compared with traditional control methods, it does not require an accurate system model, so it is more suitable for complex environments and uncertain systems. Its simple implementation also increases its practicality. In summary, this method not only ensures system stability, speed tracking accuracy and response speed, but also has good tracking accuracy and response speed for the direction angle of the mobile robot.

[0005] Based on the above background technology, the present invention intends to provide a control method of a palletizing robot using sliding mode control, which uses the advantages of sliding mode control to guide the movement strategy of the palletizing robot. Summary of the invention

[0006] The object of the present invention is to provide a sliding mode control method for a palletizing robot, so as to achieve accurate and stable control of the palletizing robot.

[0007] In order to solve the above technical problems, the present invention provides a technical solution: a sliding mode control method of a palletizing robot, comprising the following steps:

[0008] S1. Obtaining the position information of the bricks in the brick stack in the coordinate system of the stacking robot through the sensor unit provided on the stacking robot;

[0009] S2. Determine the current position of the palletizing robot in the world coordinate system according to the kinematic model of the palletizing robot;

[0010] S3, determining the expected posture of the palletizing robot in the world coordinate system according to the posture information of the bricks in the coordinate system of the palletizing robot and the current posture of the palletizing robot in the world coordinate system;

[0011] S4, determining the posture error of the palletizing robot according to the current posture and expected posture of the palletizing robot in the world coordinate system;

[0012] S5, performing sliding mode control on the current posture of the palletizing robot in the world coordinate system according to the posture error, until the posture error is less than a set threshold;

[0013] S6. Control the stacking robot to move in the set direction until the position information of the bricks in the coordinate system of the stacking robot meets the set requirements.

[0014] According to the above scheme, the sensing unit includes a depth camera and a lidar.

[0015] According to the above scheme, the method for obtaining the position information of the bricks in the brick stack in the coordinate system of the stacking robot includes:

[0016] S101, collecting data about the surrounding environment of the palletizing robot through a depth camera, and obtaining data collected by the depth camera;

[0017] S102, using the trained brick recognition algorithm to perform brick recognition on the data collected by the depth camera to determine the location information of the bricks;

[0018] S103, collecting the surrounding environment of the palletizing robot through a laser radar, and determining the original point cloud data of the bricks in combination with the position information of the bricks;

[0019] S104, determining the position and posture information of the brick in the coordinate system of the stacking robot according to the original point cloud data of the brick.

[0020] According to the above scheme, the method for determining the kinematic model includes:

[0021] S201, determining the starting position of the palletizing robot in the XY plane in the world coordinate system;

[0022] S202, determining a kinematic model of the palletizing robot according to a starting position of the palletizing robot in an XY plane in a world coordinate system.

[0023] According to the above scheme, the palletizing robot has four wheels, and the kinematic model of the palletizing robot is expressed as:

[0024]

[0025] Among them, v cx and w z are the linear velocity and angular velocity of the palletizing robot in the coordinate system of the palletizing robot, V L With V r are the speeds of the left and right wheels of the palletizing robot, c is the distance between the left and right wheels, w is c is the angular velocity of the four wheels around the instantaneous rotation center, d cy v is the distance from the instantaneous velocity center to the instantaneous rotation center of the palletizing robot projected on the y-axis of the palletizing robot coordinate system, cx is the projection of the instantaneous velocity of the palletizing robot on the x-axis of the palletizing robot coordinate system.

[0026] According to the above scheme, in step S3, the angle deviation is calculated based on the brick position obtained after preprocessing and the current posture of the robot, specifically:

[0027]

[0028] Where: θ e is the angle between the robot coordinate system X axis and the vertical line from the robot to the brick,

[0029] (x1, y1) is the coordinate of the brick in the world coordinate system, and (x0, y0) is the coordinate of the palletizing robot in the world coordinate system.

[0030] According to the above scheme, in step S4, the desired posture P * =[x1,y1,θ1], the current pose P = [x0,y0,θ0], where x i ,y i ,θ i ,i=0,1 is the position coordinate of the palletizing robot in the world coordinate system.

[0031] According to the above scheme, the method for determining the posture error of the palletizing robot according to the current posture and the expected posture of the palletizing robot in the world coordinate system includes:

[0032] According to the current position P = [x0, y0, θ0] of the palletizing robot in the world coordinate system and the expected position P *=[x1,y1,θ1], the position error Δp ​​of the palletizing robot is determined as:

[0033]

[0034] In the above formula, x e ,y e are the transformation tracking errors of the palletizing robot in the x and y directions in the world coordinate system, so the position error Δp ​​is expressed as:

[0035]

[0036] According to the above scheme, the method of performing sliding mode control on the current posture of the palletizing robot in the world coordinate system according to the posture error until the posture error is less than the set threshold includes:

[0037] S501, determine the switching function s as:

[0038] s=θ e

[0039]

[0040] S502: Determine the controller used for sliding mode control:

[0041]

[0042] Among them, k1, k2, and k3 are all constants greater than 0.

[0043] The present invention also provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the sliding mode control method of the palletizing robot described above when executing the computer program.

[0044] The beneficial effects of the present invention are as follows: the sliding mode control method of the palletizing robot provided by the present invention utilizes the characteristics of the sliding mode control, which has strong robustness, can effectively cope with changes in system parameters and external interference, and realizes rapid response and stable operation. The posture information of the bricks relative to the palletizing robot obtained by detection and the current posture of the palletizing robot in the world coordinate system are used to determine the posture error, and the palletizing robot is subjected to sliding mode control according to the posture error and the set threshold value, so that the posture of the palletizing robot gradually approaches the desired posture, and the palletizing robot moves in the direction close to the detected bricks, providing a pre-condition for the subsequent steps of the palletizing robot moving in the set direction to grasp. Compared with the existing control methods such as PID control, state space control, and adaptive control, this method not only ensures the system stability, speed tracking accuracy and response speed, but also has good tracking accuracy and response speed for the direction angle of the palletizing robot.

[0045] Furthermore, the method combines the detection information of the depth camera and the lidar to locate the bricks, which effectively improves the positioning accuracy of the bricks and thus improves the control accuracy of the sliding mode control. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 , Figure 2 This is a flow chart of a sliding mode control method of a palletizing robot according to the first embodiment of the present invention;

[0047] Figure 3 Schematic diagram of the kinematic model of the palletizing robot according to the first embodiment of the present invention;

[0048] Figure 4 is a flowchart of processing original point cloud data according to the first embodiment of the present invention;

[0049] Figure 5 Schematic diagram of a mathematical model of the relative posture relationship between the palletizing robot and bricks according to the first embodiment of the present invention;

[0050] Figure 6 It is a schematic diagram of the structure of a palletizing robot according to the second embodiment of the present invention.

[0051] Figure 3 Middle: v1, v2, v3, and v4 are the linear velocities of the left rear wheel, left front wheel, right front wheel, and right rear wheel of the palletizing robot in the coordinate system of the palletizing robot, respectively. 1x 、v 2x 、v 3x 、v 4x are the projections of the corresponding wheel linear speed on the x-axis of the palletizing robot coordinate system, v 1y 、v 2y 、v 3y 、v 4y are the projections of the corresponding wheel linear speed on the y-axis of the palletizing robot coordinate system. c 、v cx 、v cy are the instantaneous speed of the palletizing robot in the palletizing robot coordinate system, the projection of the instantaneous speed on the x-axis of the palletizing robot coordinate system, and the projection of the instantaneous speed on the y-axis of the palletizing robot coordinate system. c are the distances between the instantaneous speed center of the palletizing robot and the left rear wheel, left front wheel, right front wheel, right rear wheel and the geometric center of the palletizing robot, respectively; a is the distance between the origin of the coordinate system of the palletizing robot and the center of the rear wheel in the x-axis direction; b is the distance between the origin of the coordinate system of the palletizing robot and the center of the front wheel in the x-axis direction. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0053] Embodiment 1:

[0054] See also Figure 1 , Figure 2 , this embodiment discloses a sliding mode control method of a palletizing robot, comprising the following steps:

[0055] S1. Obtaining the position information of the bricks in the brick stack in the coordinate system of the stacking robot through the sensor unit provided on the stacking robot;

[0056] S2. Determine the current position of the palletizing robot in the world coordinate system according to the kinematic model of the palletizing robot;

[0057] S3, determining the expected posture of the palletizing robot in the world coordinate system according to the posture information of the bricks in the coordinate system of the palletizing robot and the current posture of the palletizing robot in the world coordinate system;

[0058] S4, determining the posture error of the palletizing robot according to the current posture and expected posture of the palletizing robot in the world coordinate system;

[0059] S5, performing sliding mode control on the current posture of the palletizing robot in the world coordinate system according to the posture error until the posture error is less than the set threshold value e1;

[0060] S6. Control the palletizing robot to move in the set direction (forward in this embodiment) until the posture information of the brick in the coordinate system of the palletizing robot meets the set requirements; if the radar of the palletizing robot can detect the brick during the movement in the set direction, the palletizing robot continues to move in the set direction, otherwise the method ends.

[0061] Furthermore, the sensing unit includes a depth camera and a laser radar; in this embodiment, the depth camera is a Realsence D435 depth camera.

[0062] Furthermore, the method for obtaining the position information of the bricks in the brick stack in the coordinate system of the stacking robot includes:

[0063] S101, collecting data about the surrounding environment of the palletizing robot through a depth camera, and obtaining data collected by the depth camera;

[0064] S102, using the trained brick recognition algorithm to perform brick recognition on the data collected by the depth camera to determine the location information of the bricks; in this embodiment, the yolov8 algorithm is specifically used as the brick recognition algorithm;

[0065] S103, collecting the surrounding environment of the palletizing robot through a laser radar, and determining the original point cloud data of the bricks in combination with the position information of the bricks;

[0066] S104, determine the position information of the brick in the coordinate system of the stacking robot according to the original point cloud data of the brick; the processing process of the original point cloud in this step includes voxel filtering (downsampling), coordinate transformation, straight-through filtering, Gaussian filtering, contour extraction, converting the rectangular coordinates of the original point cloud into polar coordinates, etc., and the specific process is shown in Figure 4 .

[0067] Among them, the voxel filtering process refers to creating a voxel filter to downsample the environmental data of the original point cloud data, reduce the point cloud data, and at the same time not destroy the function of the geometric structure of the point cloud itself, and remove a certain degree of noise points and outliers. Coordinate transformation refers to the initial processing of the point cloud coordinate system as the radar coordinate system. Considering the installation error between the radar and the palletizing robot, a coordinate transformation is performed on the point cloud data to make it coincide with the palletizing robot coordinate system to remove the installation error. Through filtering refers to filtering out the redundant point cloud data around the bricks in the point cloud environment, and only retaining the front point cloud of the bricks that need to be processed later. Gaussian filtering is a linear smoothing filter that further removes noise and facilitates subsequent contour extraction. Contour extraction refers to fitting the point cloud data of the bricks finally obtained, obtaining the brick contour data, and then extracting the coordinate information of the corner points of the contour based on the contour data, that is, the coordinate information of the corners of the corresponding actual bricks in the coordinate system of the palletizing robot.

[0068] Furthermore, the method for determining the kinematic model includes:

[0069] S201, determining the starting position of the palletizing robot in the XY plane in the world coordinate system;

[0070] S202, determining a kinematic model of the palletizing robot according to a starting position of the palletizing robot in an XY plane in a world coordinate system.

[0071] Further, see Figure 3 , the palletizing robot has four wheels, and the kinematic model of the palletizing robot is expressed as:

[0072]

[0073]

[0074] Among them, v cxand w z are the linear velocity and angular velocity of the palletizing robot in the coordinate system of the palletizing robot, V L With V r are the speeds of the left and right wheels of the palletizing robot, c is the distance between the left and right wheels, w is c is the angular velocity of the four wheels around the instantaneous rotation center, d cy v is the distance from the instantaneous velocity center to the instantaneous rotation center of the palletizing robot projected on the y-axis of the palletizing robot coordinate system, cx is the projection of the instantaneous velocity of the palletizing robot on the x-axis of the palletizing robot coordinate system.

[0075] Further, see Figure 5 In step S3, the angle deviation is calculated based on the brick position obtained after preprocessing and the current posture of the robot, specifically:

[0076]

[0077] Where: θ e is the angle between the robot coordinate system X axis and the vertical line from the robot to the brick,

[0078] (x1, y1) is the coordinate of the brick in the world coordinate system, and (x0, y0) is the coordinate of the palletizing robot in the world coordinate system.

[0079] Furthermore, in step S4, the desired posture P * =[x1,y1,θ1], the current pose P = [x0,y0,θ0], where x i ,y i ,θ i ,i=0,1 is the position coordinate of the palletizing robot in the world coordinate system.

[0080] Furthermore, the method for determining the posture error of the palletizing robot according to the current posture and the expected posture of the palletizing robot in the world coordinate system includes:

[0081] According to the current position P = [x0, y0, θ0] of the palletizing robot in the world coordinate system and the expected position P * =[x1,y1,θ1], the position error Δp ​​of the palletizing robot is determined as:

[0082]

[0083] In the above formula, x e ,y e are the transformation tracking errors of the palletizing robot in the x and y directions in the world coordinate system, so the position error Δp ​​is expressed as:

[0084]

[0085] Furthermore, the method of performing sliding mode control on the current posture of the palletizing robot in the world coordinate system according to the posture error until the posture error is less than a set threshold comprises:

[0086] S501, determine the switching function s as:

[0087] s=θ e

[0088]

[0089] S502: Determine the controller used for sliding mode control:

[0090]

[0091] Among them, k1, k2, and k3 are all constants greater than 0; when k1, k2, and k3 are all positive numbers, under this control law, the controlled system is globally asymptotically stable.

[0092] In order to verify the stability of the proposed vacancy rate, the V function is selected as the Lyapunov function:

[0093]

[0094] From the above two equations, it can be seen that the selected V function satisfies the Lyapunov stability condition and the proposed control rate is stable.

[0095] Embodiment 2:

[0096] This embodiment provides a palletizing robot, the palletizing robot comprising:

[0097] The sensor unit is used to obtain the position information of the brick stack in the coordinate system of the stacking robot;

[0098] A control unit, used for executing a preset sliding mode control method of a palletizing robot;

[0099] The mobile unit is controlled by the control unit and moves the palletizing robot in a certain direction;

[0100] The grabbing unit is used to grab the brick stack after the palletizing robot reaches the grabbing position of the brick stack.

[0101] The sliding mode control method of the palletizing robot comprises the following steps:

[0102] S1. Obtaining the position information of the bricks in the brick stack in the coordinate system of the stacking robot through the sensor unit provided on the stacking robot;

[0103] S2. Determine the current position of the palletizing robot in the world coordinate system according to the kinematic model of the palletizing robot;

[0104] S3, determining the expected posture of the palletizing robot in the world coordinate system according to the posture information of the bricks in the coordinate system of the palletizing robot and the current posture of the palletizing robot in the world coordinate system;

[0105] S4, determining the posture error of the palletizing robot according to the current posture and expected posture of the palletizing robot in the world coordinate system;

[0106] S5, performing sliding mode control on the current posture of the palletizing robot in the world coordinate system according to the posture error until the posture error is less than the set threshold value e1;

[0107] S6. Control the palletizing robot to move in the set direction (forward in this embodiment) until the posture information of the brick in the coordinate system of the palletizing robot meets the set requirements; if the radar of the palletizing robot can detect the brick during the movement in the set direction, the palletizing robot continues to move in the set direction, otherwise the method ends.

[0108] Furthermore, the sensing unit includes a depth camera and a laser radar; in this embodiment, the depth camera is a Realsence D435 depth camera.

[0109] Furthermore, the method for obtaining the position information of the bricks in the brick stack in the coordinate system of the stacking robot includes:

[0110] S101, collecting data about the surrounding environment of the palletizing robot through a depth camera, and obtaining data collected by the depth camera;

[0111] S102, using the trained brick recognition algorithm to perform brick recognition on the data collected by the depth camera to determine the location information of the bricks; in this embodiment, the yolov8 algorithm is specifically used as the brick recognition algorithm;

[0112] S103, collecting the surrounding environment of the palletizing robot through a laser radar, and determining the original point cloud data of the bricks in combination with the position information of the bricks;

[0113] S104. Determine the posture information of the brick in the coordinate system of the stacking robot based on the original point cloud data of the brick; the processing process of the original point cloud in this step includes voxel filtering (downsampling), coordinate transformation, pass filtering, Gaussian filtering, contour extraction, converting the rectangular coordinates of the original point cloud into polar coordinates, etc.

[0114] Furthermore, the method for determining the kinematic model includes:

[0115] S201, determining the starting position of the palletizing robot in the XY plane in the world coordinate system;

[0116] S202, determining a kinematic model of the palletizing robot according to a starting position of the palletizing robot in an XY plane in a world coordinate system.

[0117] Furthermore, the palletizing robot has four wheels, and the kinematic model of the palletizing robot is expressed as:

[0118]

[0119] Among them, v cx and w z are the linear velocity and angular velocity of the palletizing robot in the coordinate system of the palletizing robot, V L With V r are the speeds of the left and right wheels of the palletizing robot, c is the distance between the left and right wheels, w is c is the angular velocity of the four wheels around the instantaneous rotation center, d cy v is the distance from the instantaneous velocity center to the instantaneous rotation center of the palletizing robot projected on the y-axis of the palletizing robot coordinate system, cx is the projection of the instantaneous velocity of the palletizing robot on the x-axis of the palletizing robot coordinate system.

[0120] Furthermore, in step S3, the angle deviation is calculated based on the brick position obtained after preprocessing and the current posture of the robot, specifically:

[0121]

[0122] Where: θ e is the angle between the robot coordinate system X axis and the vertical line from the robot to the brick,

[0123] (x1, y1) is the coordinate of the brick in the world coordinate system, and (x0, y0) is the coordinate of the palletizing robot in the world coordinate system.

[0124] Furthermore, in step S4, the desired posture P * =[x1,y1,θ1], the current pose P = [x0,y0,θ0], where x i ,y i ,θ i ,i=0,1 is the position coordinate of the palletizing robot in the world coordinate system.

[0125] Furthermore, the method for determining the posture error of the palletizing robot according to the current posture and the expected posture of the palletizing robot in the world coordinate system includes:

[0126] According to the current position P = [x0, y0, θ0] of the palletizing robot in the world coordinate system and the expected position P *=[x1,y1,θ1], the position error Δp ​​of the palletizing robot is determined as:

[0127]

[0128] In the above formula, x e ,y e are the transformation tracking errors of the palletizing robot in the x and y directions in the world coordinate system, so the position error Δp ​​is expressed as:

[0129]

[0130] Furthermore, the method of performing sliding mode control on the current posture of the palletizing robot in the world coordinate system according to the posture error until the posture error is less than a set threshold comprises:

[0131] S501, determine the switching function s as:

[0132] s=θ e

[0133]

[0134] S502: Determine the controller used for sliding mode control:

[0135]

[0136] Among them, k1, k2, and k3 are all constants greater than 0; when k1, k2, and k3 are all positive numbers, under this control law, the controlled system is globally asymptotically stable.

[0137] Embodiment three:

[0138] This embodiment discloses a computer device for implementing the method described in Embodiment 1. The computer device may be a smart phone, a tablet computer, a laptop computer, a desktop computer, a rack server, a blade server, a tower server or a cabinet server (including an independent server, or a server cluster composed of multiple servers) that can execute a program. The computer device of this embodiment includes at least, but is not limited to: a memory and a processor that can be interconnected through a system bus. It should be noted that only a computer device with components is shown, but it should be understood that it is not required to implement all the components shown, and more or fewer components may be implemented instead.

[0139] In this embodiment, the memory (i.e., readable storage medium) includes flash memory, hard disk, multimedia card, card-type memory (e.g., SD or DX memory, etc.), random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM). The memory may also be an external storage device of a computer device, such as a plug-in hard disk equipped on the computer device, a smart memory card (SmartMedia Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. Of course, the memory may also include both the internal storage unit of the computer device and its external storage device. In this embodiment, the memory is generally used to store the operating system and various application software installed on the computer device, such as the program code of the sliding mode control method of the palletizing robot in the first embodiment. In addition, the memory may also be used to temporarily store various types of data that have been output or are to be output.

[0140] The processor may be a central processing unit (CPU), a controller, a microcontroller, a microprocessor, or other data processing chip in some embodiments. The processor is generally used to control the overall operation of a computer device. In this embodiment, the processor is used to run program codes stored in a memory or process data, such as running a sliding mode control method for a palletizing robot.

[0141] Embodiment 4:

[0142] The present embodiment provides a computer-readable storage medium, such as a flash memory, a hard disk, a multimedia card, a card-type memory (e.g., an SD or DX memory, etc.), a random access memory (RAM), a static random access memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a programmable read-only memory (PROM), a magnetic memory, a disk, an optical disk, a server, an App application store, etc., on which a computer program is stored, and the program is executed by a processor to implement the corresponding function. The computer-readable storage medium of the present embodiment is used to store the program code of the sliding mode control method of the palletizing robot, and when executed by the processor, the sliding mode control method of the palletizing robot of the first embodiment is implemented.

[0143] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0144] It should be pointed out that, according to the needs of implementation, the various steps / components described in this application can be split into more steps / components, and two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0145] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A sliding mode control method for a palletizing robot, characterized in that: The following steps are involved: S1. Obtaining the position information of the bricks in the brick stack in the coordinate system of the stacking robot through the sensor unit provided on the stacking robot; S2. Determine the current position of the palletizing robot in the world coordinate system according to the kinematic model of the palletizing robot; S3, determining the expected posture of the palletizing robot in the world coordinate system according to the posture information of the bricks in the coordinate system of the palletizing robot and the current posture of the palletizing robot in the world coordinate system; S4, determining the posture error of the palletizing robot according to the current posture and expected posture of the palletizing robot in the world coordinate system; S5, performing sliding mode control on the current posture of the palletizing robot in the world coordinate system according to the posture error, until the posture error is less than a set threshold; S6. Control the stacking robot to move in the set direction until the position information of the bricks in the coordinate system of the stacking robot meets the set requirements.

2. The sliding mode control method of the palletizing robot according to claim 1, characterized in that: The sensing unit includes a depth camera and a lidar.

3. The sliding mode control method of the palletizing robot according to claim 2, characterized in that: The method for obtaining the position information of the bricks in the brick stack in the coordinate system of the stacking robot comprises: S101, collecting data about the surrounding environment of the palletizing robot through a depth camera, and obtaining data collected by the depth camera; S102, using the trained brick recognition algorithm to perform brick recognition on the data collected by the depth camera to determine the location information of the bricks; S103, collecting the surrounding environment of the palletizing robot through a laser radar, and determining the original point cloud data of the bricks in combination with the position information of the bricks; S104, determining the position and posture information of the brick in the coordinate system of the stacking robot according to the original point cloud data of the brick.

4. The sliding mode control method of the palletizing robot according to claim 1, characterized in that: The method for determining the kinematic model includes: S201, determining the starting position of the palletizing robot in the XY plane in the world coordinate system; S202, determining a kinematic model of the palletizing robot according to a starting position of the palletizing robot in an XY plane in a world coordinate system.

5. The sliding mode control method of the palletizing robot according to claim 4, characterized in that: The palletizing robot has four wheels, and the kinematic model of the palletizing robot is expressed as: Among them, v cx and w z are the linear velocity and angular velocity of the palletizing robot in the coordinate system of the palletizing robot, V L With V r are the speeds of the left and right wheels of the palletizing robot, c is the distance between the left and right wheels, w is c is the angular velocity of the four wheels around the instantaneous rotation center, d cy v is the distance from the instantaneous velocity center to the instantaneous rotation center of the palletizing robot projected on the y-axis of the palletizing robot coordinate system, cx is the projection of the instantaneous velocity of the palletizing robot on the x-axis of the palletizing robot coordinate system.

6. The sliding mode control method of the palletizing robot according to claim 1, characterized in that: In step S3, the angle deviation is calculated based on the brick position obtained after preprocessing and the current posture of the robot, specifically: Where: θ e is the angle between the robot coordinate system X axis and the vertical line from the robot to the brick, (x1, y1) is the coordinate of the brick in the world coordinate system, and (x0, y0) is the coordinate of the palletizing robot in the world coordinate system.

7. The sliding mode control method of the palletizing robot according to claim 6, characterized in that: In step S4, the desired posture P * =[x1,y1,θ1], the current pose P = [x0,y0,θ0], where x i ,y i ,θ i ,i=0,1 is the position coordinate of the palletizing robot in the world coordinate system.

8. The sliding mode control method of the palletizing robot according to claim 7, characterized in that: The method for determining the posture error of the palletizing robot according to the current posture and the expected posture of the palletizing robot in the world coordinate system includes: According to the current position P = [[x0, y0, θ0] of the palletizing robot in the world coordinate system and the expected position P * =[x1,y1,θ1], the position error Δp ​​of the palletizing robot is determined as: In the above formula, x e ,y e are the transformation tracking errors of the palletizing robot in the x and y directions in the world coordinate system, so the position error Δp ​​is expressed as:

9. The sliding mode control method of the palletizing robot according to claim 8, characterized in that: The method of performing sliding mode control on the current posture of the palletizing robot in the world coordinate system according to the posture error until the posture error is less than a set threshold comprises: S501, determine the switching function s as: s=θ e S502: Determine the controller used for sliding mode control: Among them, k1, k2, and k3 are all constants greater than 0.

10. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the sliding mode control method of the palletizing robot according to any one of claims 1 to 9 are implemented.

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