A motion control method, device, and storage medium for a ball-controlled robot.

Abstract

This invention discloses a motion control method, device, and storage medium for a ball-controlling robot. The method includes: acquiring the motion parameters of a ball through a binocular vision system; determining control parameters for the ball table based on the ball control objective, the motion parameters, and the current posture of the table; the ball control objective includes basic movements such as juggling, catching, balancing, and tracking, as well as composite movements based on multiple basic movements; the motion axes of the ball table include rotation around the X-axis, rotation around the Y-axis, and height value around the Z-axis; and controlling the operation of each motor based on the control parameters to achieve the ball control objective. In this invention, acquiring the ball's motion parameters based on vision and determining the control parameters for the ball table based on the ball control objective and motion parameters can realize multiple ball control functions. Using this motion control method, data acquisition and control training can be performed to obtain ball attributes, and the parameters of various ball control methods can be modulated. The acquired data and the modulated data can be used to guide athletes and to set control parameters for dedicated training robots.

Description

Technical Field

[0001] This invention relates to the field of robotics, and in particular to a motion control method, device, and storage medium for a ball-controlling robot. Background Technology

[0002] Ball sports are an important part of sports. In order to study the various motion properties of the ball and obtain data that can be used to guide athletes' strategies, it is necessary to use ball control robots to perform various ball control actions. In the existing technology, patent CN114378795A discloses a five-degree-of-freedom parallel table tennis robot. This robot is mainly used for training against humans, has a single function, and does not disclose specific implementation methods. Summary of the Invention

[0003] Purpose of the invention: In order to overcome the shortcomings of the existing technology, the present invention provides a motion control method, device and storage medium for a ball-controlling robot that can realize rich ball control functions.

[0004] Technical solution: To achieve the above objectives, the present invention provides a motion control method for a ball-controlling robot, the method comprising:

[0005] The motion parameters of the ball are obtained through a binocular vision system;

[0006] Based on the ball control objective, the motion parameters, and the current posture of the table, control parameters for the table are determined. The ball control objective includes basic movements such as juggling, catching, balancing, and making the ball follow a trajectory, as well as composite movements based on multiple basic movements. The control parameters include at least one of the following three: the target motion amount of each motion axis of the table, the kinematic parameters of the table, and the time parameters. The motion axes of the table include the rotation amount around the X-axis, the rotation amount around the Y-axis, and the height value of the Z-axis.

[0007] The operation of each motor is controlled based on the control parameters, so that the movement of the ball table achieves the purpose of ball control.

[0008] Furthermore, when the purpose of ball control is to balance the ball or make the ball follow a trajectory, controlling the operation of each motor based on the control parameters to make the table move to achieve the purpose of ball control includes:

[0009] The target angle to be rotated by each motor is determined based on the target motion amount of each motion axis;

[0010] The inverse kinematics solution of the ball-controlling robot is obtained using geometric methods;

[0011] The inverse kinematics solution is mapped to the target angle to be rotated by each corresponding motor;

[0012] The operation of each motor is controlled based on the target angle.

[0013] Furthermore, when the ball control objective is to juggle the ball, controlling the operation of each motor based on the control parameters to make the table move to achieve the ball control objective includes:

[0014] The remaining hitting time is obtained based on the Z-axis coordinate value in the motion parameters and the ball speed calculation time parameter.

[0015] Calculate the target's hitting speed based on the ball speed and the height of the target's bounce;

[0016] If the remaining time for hitting the ball is between the start time and the stop time, then the table is controlled to juggle the ball based on the target hitting speed.

[0017] Furthermore, the control of each motor based on the control parameters specifically includes:

[0018] The motors are controlled by a PID controller. The input values ​​of the PID controller include the target rotation angle Rx1 of the ball table around the X-axis, the target rotation angle Ry1 of the ball table around the Y-axis, and the target height value z1. The output values ​​are the actual rotation angle Rx2 of the ball table around the X-axis, the actual rotation angle Ry2 of the ball table around the Y-axis, and the actual height value z2. When the purpose of ball control is to balance the ball or to make the ball follow a line on the ball table, the input and output values ​​of the PID controller do not include the height value.

[0019] Furthermore, when the purpose of ball control is to juggle the ball, when performing PID control on the height value of the table, the output amplitude of the PID controller is limited, specifically including:

[0020] Calculate the velocity difference between the ball and the table.

[0021] The speed difference is limited to keep it within a preset range;

[0022] Calculate the maximum output limit of the PID controller based on the relative speed between the ball and the table after the limit is set.

[0023] The height of the table tennis table is controlled by PID based on the maximum output limit.

[0024] A motion control device for a ball-controlling robot, comprising:

[0025] The motion parameters of the ball are obtained through a binocular vision system;

[0026] Based on the ball control objective, the motion parameters, and the current posture of the table, control parameters for the table are determined. The ball control objective includes basic movements such as juggling, catching, balancing, and making the ball follow a trajectory, as well as composite movements based on multiple basic movements. The control parameters include at least one of the following three: the target motion amount of each motion axis of the table, the kinematic parameters of the table, and the time parameters. The motion axes of the table include the rotation amount around the X-axis, the rotation amount around the Y-axis, and the height value of the Z-axis.

[0027] The operation of each motor is controlled based on the control parameters, so that the movement of the ball table achieves the purpose of ball control.

[0028] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the motion control method for a ball-controlling robot as described above.

[0029] Beneficial effects: The motion control method, device, and storage medium of the ball-controlling robot of the present invention have the following technical effects:

[0030] (1) By acquiring the ball's motion parameters based on vision and determining the control parameters of the table based on the ball control purpose and motion parameters, various ball control functions can be realized. Using this motion control method, data acquisition and control training can be carried out to obtain the ball's attributes, and the parameters of various ball control methods can be modulated, such as the timing, force, and speed of bouncing. The acquired data and the modulated data can be used to guide athletes and to set control parameters for dedicated training robots.

[0031] (2) The remaining hitting time was used to implement the time-control strategy. Based on the remaining hitting time, it was determined whether to perform the juggling action, which could ensure that the ball could be juggled successfully.

[0032] (3) By limiting the speed difference between the ball and the table, and then calculating the maximum output limit based on the relative speed between the ball and the table, the table can be reasonably and effectively controlled. This fully considers the structural characteristics of the ball control robot and the properties of the ball-bouncing motion, and can achieve the purpose of bouncing within the allowable range of the mechanical structure. Attached Figure Description

[0033] Figure 1 This is a structural diagram of a ball-controlling robot;

[0034] Figure 2 A simplified diagram of the ball control mechanism;

[0035] Figure 3 This is a flowchart illustrating the motion control method for a ball-controlling robot.

[0036] In the diagram: 1- Motion control device ball control mechanism; 11- Base; 12- Table tennis table; 13- First arm; 14- Second arm; 15- Motor; 2- Binocular vision system. Detailed Implementation

[0037] The invention will now be further described with reference to the accompanying drawings.

[0038] The motion control method of the ball-controlling robot of the present invention is based on, for example, Figure 1 The ball control robot shown includes a ball control mechanism 1 and a binocular vision system 2 mounted on the ball control mechanism 1. The ball control mechanism 1 includes a base 11, a ball table 12, and three sets of drive mechanisms disposed between the base 11 and the ball table 12. Each set of drive mechanisms includes a first arm 13 connected to the base 11 and a second arm 14 connected to the ball table 12. The first arm 13 and the second arm 14 are rotatably connected. A motor 15 is disposed between the first arm 13 and the base 11. The second arm 14 is connected to the ball table 12 through a ball joint. The binocular vision system 2 is installed directly above the table 12. The binocular vision system 2 and the motors 15 of all drive mechanisms are connected to the controller. The controller can obtain the position of the robot through the binocular vision system 2, and can control the movement of the table 12 by controlling the operation of each motor 15 according to the purpose of ball control, so as to realize the interaction between the table 12 and the ball. This invention is illustrated using table tennis as an example. Applying the method of this invention to other sports balls such as football, basketball, and tennis, as well as applying the method of this invention to the field of ball control of other non-sports attributes, should also be regarded as falling within the protection scope of this invention.

[0039] A motion control method for a ball-controlled robot, such as Figure 3 As shown, the method includes the following steps S101-S103:

[0040] Step S101: Obtain the motion parameters of the ball through a binocular vision system;

[0041] In this step, the motion parameters include the three-dimensional position coordinates of the ball, velocity (including falling velocity or movement velocity on the table 12), and other values.

[0042] Step S102: Based on the ball control objective, the motion parameters, and the current posture of the table 12, determine the control parameters for the table 12. The ball control objective includes basic movements such as juggling, catching, balancing, and making the ball follow a trajectory, as well as composite movements based on multiple basic movements. The control parameters include at least one of the following three: the target motion amount of each motion axis of the table 12, the kinematic parameters of the table 12, and the time parameters. The motion axes of the table 12 include the rotation amount around the X-axis, the rotation amount around the Y-axis, and the height value of the Z-axis. The kinematic parameters include parameters such as the motion speed and acceleration of the table 12, and the time parameters determine the time it takes for the table 12 to reach a certain motion position to grasp the timing of acting on the ball.

[0043] In this step, the ball control objective of juggling is to make the ball bounce after hitting the table 12. This requires a certain relative speed between the ball and the table 12. Depending on the real-time requirements of the juggling height, the table 12 can move upwards to meet the ball, maintain its height position, or even move in the direction of the ball's movement. Catching the ball involves moving the table 12 in the direction of the ball's descent so that the ball stops on the table 12 after contact. Balancing the ball involves keeping it within a predetermined range, which can be a point or a surface. Tracking the ball on the table 12 involves controlling the movement of the table 12 so that the ball moves relative to the table 12 along a target trajectory. The target trajectory can be a circle, polygon, heart, or other user-defined trajectory shape. A combined movement could be juggling the ball while simultaneously tracking it.

[0044] Depending on the purpose of ball control, the motion axes of the table 12 may differ, and the required control parameters will also vary. For example, when balancing the ball or making it follow a trajectory, the Z-axis height remains constant, while the table 12 needs to rotate around the X and Y axes. When juggling the ball, the main control is the change in the Z-axis height, and kinematic and time parameters are needed to control the force and timing of the shot. When juggling the ball while making it follow a trajectory, the values ​​of all three motion axes need to change.

[0045] Step S103: Control each motor 15 to operate based on the control parameters so that the ball table 12 moves to achieve the purpose of ball control.

[0046] In the above steps, the motion parameters of the ball are acquired based on vision, and the control parameters of the table 12 are determined based on the ball control purpose and motion parameters, enabling various ball control functions. Using this motion control method, data acquisition and control training can be performed to obtain the ball's attributes, and the parameters of various ball control methods can be modulated, such as the timing, force, and speed of bouncing. The acquired and modulated data can be used to guide athletes and to set control parameters for dedicated training robots.

[0047] Preferably, when the purpose of ball control is to balance the ball or make the ball follow a trajectory, the step S103 above, which involves controlling the operation of each motor 15 based on the control parameters to make the table 12 move to achieve the purpose of ball control, includes the following steps S201-S204:

[0048] Step S201: Determine the target angle to be rotated by each motor 15 based on the target motion amount of each motion axis;

[0049] Step S202: Obtain the inverse kinematics solution of the ball-controlling robot according to the geometric method, and obtain the posture corresponding to each first arm 13;

[0050] In this step, the purpose of performing inverse kinematics solutions is to obtain the motion quantities of each drive mechanism based on the target motion quantities of each motion axis of the ball table 12. Specifically, the calculations are performed based on the world coordinate system O-XYZ. A simplified diagram of the ball control robot model is shown below. Figure 2 As shown, A1, A2, and A3 are three points on the output shaft of motor 15. These three points are all revolute joints, and the connecting line of these three points forms an equilateral triangle. Point O of the O-XYZ coordinate system is located at the center of this equilateral triangle. Point A2 is located on the Y-axis, and the Z-axis is perpendicular to the equilateral triangle. B1, B2, and B3 are revolute joints between the first arm 13 and the second arm 14 in each drive mechanism. C1, C2, and C3 are the planes formed by the three ball joints connecting the ball table 12 to the second arm 14. These three points are ball joints, and the connecting line of these three ball joints forms an equilateral triangle.

[0051] Based on the above simplified diagram and coordinate system, the inverse kinematics solution process is as follows: In the world coordinate system described above, the three-dimensional coordinates of A1, A2, and A3 remain unchanged. Taking the three joints A1, B1, and C1 as examples, the known parameters are the rotation angles of the ball table 12 relative to the X and Y axes. The coordinate values ​​of C1 relative to the initial coordinates can be obtained, where the initial coordinates of C1, C2, and C3 are obtained when the ball table 12 is in a given initial position. Given the arm lengths L1 and L2 of the first arm 13 and the second arm 14, θ1 is obtained through trigonometric calculations. θ1 is an angle value directly related to the rotation angle of the motor 15. Using the same method, the attitude angles of the first arm 13 at positions A2 and A3 can be solved.

[0052] Step S203: Demap the inverse kinematics to the target angle to be rotated by each corresponding motor 15; In this step, the target angle corresponding to each motor 15 can be easily obtained based on the attitude angle θ1 of each first arm 13.

[0053] Step S204: Control the operation of each of the motors 15 based on the target angle.

[0054] Preferably, when the ball control objective is to juggle the ball, the step S103 above, which involves controlling the operation of each motor 15 based on the control parameters to move the table 12 and achieve the ball control objective, includes the following steps S301-S303:

[0055] Step S301: Obtain the remaining hitting time based on the Z-axis coordinate value and ball speed calculation time parameter in the motion parameters;

[0056] Step S302: Calculate the target hitting speed based on the ball speed and the target bouncing height;

[0057] Step S303: Determine whether the remaining hitting time is between the start time and the stop time. If so, control the table 12 to juggle the ball based on the target hitting speed.

[0058] In the above steps, a timing strategy is implemented using the remaining striking time. The decision to perform a juggling action is based on the remaining striking time, ensuring successful juggling. The start time is the earliest time a striking action can be performed. If the vertical distance between the ball and the table 12 is too far, the motor 15 will exhibit runaway motion during motion planning, exceeding the robot's movement space and potentially causing structural damage. The stop time is the latest time a striking action can be performed. If the vertical distance between the ball and the table 12 is too close, the motor will not be able to respond quickly enough, requiring a large acceleration in a short time; this situation must be avoided. Between the start and stop times, the table 12 is at a height where ball control is possible; this height is limited by the remaining striking time. During each juggling action, the target height can be customized. Based on this height, parameters such as the ball's movement time, the juggling timing, and the required speed of the table can be obtained.

[0059] Preferably, the step S103 above, which involves controlling the operation of each motor 15 based on the control parameters, specifically includes:

[0060] The motors 15 are controlled by a PID controller. The input values ​​of the PID controller include the target rotation angle Rx1 of the ball table 12 around the X-axis, the target rotation angle Ry1 of the ball table 12 around the Y-axis, and the target height value z1. The output values ​​are the actual rotation angle Rx2 of the ball table 12 around the X-axis, the actual rotation angle Ry2 of the ball table 12 around the Y-axis, and the actual height value z2. When the purpose of ball control is to balance the ball or to make the ball follow a line on the ball table 12, the input and output values ​​of the PID controller do not include the height value.

[0061] Preferably, when the purpose of ball control is to juggle the ball, when performing PID control on the height value of the table 12, the output amplitude of the PID controller is limited, specifically including the following steps S401-S404:

[0062] Step S401: Calculate the velocity difference between the ball and the table 12;

[0063] Step S402: Limit the speed difference to keep it within a preset range;

[0064] Step S403: Calculate the maximum output limit of the PID controller based on the relative speed between the ball and the table 12 after the limit is set. The output limit is inversely proportional to the relative speed; that is, when the relative speed is small, the output limit is large, and when the relative speed is large, the output limit is small.

[0065] Step S404: Perform PID control on the height value of the ball table 12 based on the maximum output limit.

[0066] By sampling the above scheme, limiting the speed difference between the ball and the table 12, and then calculating the maximum output limit based on the relative speed between the ball and the table 12, reasonable and effective control of the table 12 can be achieved. This fully considers the structural characteristics of the ball control robot and the properties of the ball-bouncing motion, and can achieve the purpose of bouncing the ball within the allowable range of the mechanical structure.

[0067] When receiving the ball, the controller controls the ball table 1 to move in the same direction as the ball, and makes the instantaneous speed of the ball table 1 when receiving the ball the same as that of the ball, or the difference between their relative speeds is less than a preset range. After receiving the ball, the ball table 1 decelerates to gradually counteract the kinetic energy of the ball, eventually bringing the ball to a stop.

[0068] This invention also provides a motion control device for a ball-controlling robot. The motion control device may include or be divided into one or more program modules. One or more program modules are stored in a storage medium and executed by one or more processors to complete this invention and implement the aforementioned motion control method. The program module referred to in this embodiment of the invention refers to a series of computer program instruction segments capable of performing a specific function, which is more suitable than the program itself for describing the execution process of the motion control method in the storage medium. The following description will specifically introduce the functions of each program module in this embodiment, including:

[0069] The acquisition module 510 acquires the motion parameters of the ball through a binocular vision system;

[0070] Here, motion parameters include the ball's three-dimensional position coordinates, velocity (including falling velocity or velocity on the table 12), and other values.

[0071] The calculation module 520 determines the control parameters for the table tennis table 12 based on the ball control objective, the motion parameters, and the current posture of the table tennis table 12. The ball control objective includes basic movements such as juggling, catching, balancing, and making the ball follow a trajectory, as well as composite movements based on multiple basic movements. The control parameters include at least one of the target motion quantities of each motion axis of the table tennis table 12, the kinematic parameters of the table tennis table 12, and the time parameters. The motion axes of the table tennis table 12 include the rotation amount around the X-axis, the rotation amount around the Y-axis, and the height value of the Z-axis. The kinematic parameters include parameters such as the motion speed and acceleration of the table tennis table 12, and the time parameters determine the time it takes for the table tennis table 12 to reach a certain motion position in order to grasp the timing of acting on the ball.

[0072] Depending on the purpose of ball control, the motion axes of the table 12 may differ, and the required control parameters will also vary. For example, when balancing the ball or making it follow a trajectory, the Z-axis height remains constant, while the table 12 needs to rotate around the X and Y axes. When juggling the ball, the main control is the change in the Z-axis height, and kinematic and time parameters are needed to control the force and timing of the shot. When juggling the ball while making it follow a trajectory, the values ​​of all three motion axes need to change.

[0073] The implementation module 530 controls the operation of each motor 15 based on the control parameters, so as to make the ball table 12 move to achieve the purpose of ball control.

[0074] Other aspects of implementing the above motion control method based on motion control devices have been described in detail in previous embodiments. Please refer to the corresponding content in the previous embodiments. They will not be repeated here.

[0075] The present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the motion control method for the ball-controlling robot as described above.

[0076] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A motion control method for a ball-controlled robot, characterized in that, The method includes: The motion parameters of the ball are obtained through a binocular vision system; Based on the ball control objective, the motion parameters, and the current posture of the table (12), control parameters for the table (12) are determined; the ball control objective includes basic movements such as juggling, catching, balancing, and making the ball follow a path, as well as composite movements based on multiple basic movements; the control parameters include at least one of the target motion quantities of each motion axis of the table (12), the kinematic parameters of the table (12), and the time parameters; the motion axes of the table (12) include the rotation amount around the X-axis, the rotation amount around the Y-axis, and the height value of the Z-axis; Based on the control parameters, each motor (15) is controlled to operate so that the ball table (12) moves to achieve the purpose of ball control; When the ball control objective is to juggle the ball, controlling each motor (15) to operate based on the control parameters to move the table (12) to achieve the ball control objective includes: The remaining hitting time is obtained based on the Z-axis coordinate value in the motion parameters and the ball speed calculation time parameter. Calculate the target's hitting speed based on the ball speed and the height of the target's bounce; Determine whether the remaining hitting time is between the start time and the stop time. If so, control the table (12) to juggle the ball based on the target hitting speed. When the purpose of ball control is to juggle the ball, when performing PID control on the height value of the table (12), the output amplitude of the PID controller is limited, specifically including: Calculate the velocity difference between the ball and the table (12); The speed difference is limited to keep it within a preset range; The maximum output limit of the PID controller is calculated based on the relative speed between the ball and the table (12) after the limit is set. The height of the ball table (12) is controlled by PID based on the maximum output limit.

2. The motion control method for the ball-controlling robot according to claim 1, characterized in that, When the ball control objective is to balance the ball or make the ball follow a trajectory, the step of controlling the operation of each motor (15) based on the control parameters to make the table (12) move to achieve the ball control objective includes: The target angle to be rotated by each motor (15) is determined based on the target motion amount of each motion axis; The inverse kinematics solution of the ball-controlling robot is obtained using geometric methods; The inverse kinematics solution is mapped to the target angle to be rotated by each corresponding motor (15); The operation of each motor (15) is controlled based on the target angle.

3. The motion control method for the ball-controlling robot according to claim 1, characterized in that, The control of each motor (15) based on the control parameters is specifically as follows: The motors (15) are controlled by a PID controller, wherein the input values ​​of the PID controller include the target rotation angle R of the ball table (12) around the X-axis. x1 The target rotation angle R of the table (12) around the Y-axis y1 The target height value z1, the output value is the actual rotation angle Rx2 of the ball table (12) around the X axis, the actual rotation angle Ry2 of the ball table (12) around the Y axis and the actual height value z2; when the purpose of ball control is to balance the task or to make the ball follow the track on the ball table (12), the input and output values ​​of the PID controller do not include the height value.

4. A motion control device for a ball-controlling robot, characterized in that, It includes: The acquisition module obtains the ball's motion parameters through a binocular vision system; The calculation module determines the control parameters of the table (12) based on the ball control objective, the motion parameters, and the current posture of the table (12). The ball control objective includes basic movements such as juggling, catching, balancing, and making the ball follow a trajectory, as well as composite movements based on multiple basic movements. The control parameters include at least one of the target motion amount of each motion axis of the table (12), the kinematic parameters of the table (12), and the time parameters. The motion axes of the table (12) include the rotation amount around the X-axis, the rotation amount around the Y-axis, and the height value of the Z-axis. The implementation module controls the operation of each motor (15) based on the control parameters so that the ball table (12) moves to achieve the purpose of ball control; When the ball control objective is to juggle the ball, controlling each motor (15) to operate based on the control parameters to move the table (12) to achieve the ball control objective includes: The remaining hitting time is obtained based on the Z-axis coordinate value in the motion parameters and the ball speed calculation time parameter. Calculate the target's hitting speed based on the ball speed and the height of the target's bounce; Determine whether the remaining hitting time is between the start time and the stop time. If so, control the table (12) to juggle the ball based on the target hitting speed. When the purpose of ball control is to juggle the ball, when performing PID control on the height value of the table (12), the output amplitude of the PID controller is limited, specifically including: Calculate the velocity difference between the ball and the table (12); The speed difference is limited to keep it within a preset range; The maximum output limit of the PID controller is calculated based on the relative speed between the ball and the table (12) after the limit is set. The height of the ball table (12) is controlled by PID based on the maximum output limit.

5. A computer-readable storage medium, characterized in that, It stores a computer program, which, when executed by a processor, implements the motion control method for the ball-controlling robot as described in any one of claims 1-3.

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