Tennis ball serving robot and tennis ball serving system

Abstract

The invention provides a tennis ball serving robot and a tennis ball serving system, the tennis ball serving robot responds to a user-defined ball serving instruction of a user, enters a user-defined ball serving mode based on the user-defined ball serving instruction of the user, and performs user-defined ball serving according to received user-defined ball serving parameters in the user-defined ball serving mode. The consistency and switching control of tennis ball falling points can be improved, and the ball serving route is improved; the interaction is more visual and simpler; the capability and the application scene of the tennis serving robot are improved; and equipment maintenance is safer and more convenient.

Description

Technical Field

[0001] The invention belongs to the technical field of sports equipment, and in particular relates to a tennis serving robot and a tennis serving system. Background Art

[0002] With the popularity of tennis and the improvement of technical level, the demand for tennis serving robots is growing. Most of the existing extruded tennis serving robots adopt traditional mechatronics design, aiming to provide users with stable serving practice. However, a series of problems in the actual use of such devices limit their support for training effects and user experience, which are specifically manifested in the following aspects: the preset serving mode is too single, the consistency of tennis ball landing point is poor, there is a lack of tennis ball speed adjustment function, inconvenient fault handling, and lack of effective interactive mechanism. Summary of the invention

[0003] In order to overcome the problems existing in the related art at least to a certain extent, the present invention provides a tennis serving robot and a tennis serving system.

[0004] According to a first aspect of an embodiment of the present invention, the present invention provides a tennis serving robot, which responds to a user's customized serving instruction, enters a customized serving mode based on the user's customized serving instruction, and performs a customized serve according to received customized serving parameters in the customized serving mode.

[0005] According to an embodiment of the present invention, a tennis serving robot is provided, which includes a robot body and a ball collecting basket, a controller, a ball sending module, a ball squeezing module, a pitch module and a left and right module arranged on the robot body; wherein the ball collecting basket is arranged above the ball sending module, and the ball sending module, the ball squeezing module, the pitch module and the left and right modules are all connected to the controller; the ball sending module is used to obtain the collected tennis balls from the ball collecting basket and transport the tennis balls to the ball squeezing module, the ball squeezing module is used to squeeze the tennis balls to achieve serving, and the pitch module and the left and right modules are used to adjust the up and down and left and right directions of the tennis balls squeezed by the ball squeezing module.

[0006] Furthermore, the tennis serving robot also includes a hatch module, which is connected to the controller and is used to respond to the user's hatch opening and closing instructions to open or close the hatch.

[0007] Furthermore, the ball delivery module includes a ball delivery motor and a photoelectric sensor, both of which are connected to the controller, and the photoelectric sensor is arranged in the ball delivery channel to detect information that a tennis ball enters the ball delivery channel; the controller is used to receive a signal from the photoelectric sensor and control the action of the ball delivery motor based on the received signal; when the photoelectric sensor detects that a tennis ball enters the ball delivery channel, the controller stops the ball delivery motor in response to the signal sent by the photoelectric sensor, and restarts the ball delivery motor after the tennis ball completely passes through the ball delivery channel, thereby ensuring that only one tennis ball is delivered each time.

[0008] Furthermore, the ball squeezing module includes an upper wheel motor, a lower wheel motor, an upper wheel speed sensor and a lower wheel speed sensor, and the upper wheel motor, the lower wheel motor, the upper wheel speed sensor and the lower wheel speed sensor are all connected to the controller, and the upper wheel speed sensor and the lower wheel speed sensor respectively detect the rotational speed of the upper wheel motor and the lower wheel motor, and send the detected rotational speed to the controller, and the controller adjusts the rotational speed of the upper wheel motor and the lower wheel motor in real time according to the received rotational speed.

[0009] Furthermore, the upper wheel speed v of the squeezing wheel is obtained according to the serving speed, the serving rotation type and the serving rotation speed. u and the lower wheel speed v d They are:

[0010]

[0011] Among them, k u , k d , k c ,q u ,q d and q c They represent the linear fitting coefficients, v n represents the speed of the tennis ball, w n represents the serve rotation speed vector, which is composed of the serve rotation type and the serve rotation speed magnitude w s The combined parameters.

[0012] Further, the pitch module includes a pitch motor and a pitch angle sensor, both of which are connected to the controller, and the pitch angle sensor is used to detect the pitch angle of the pitch motor and send it to the controller, and the controller performs closed-loop control on the pitch motor;

[0013] The left and right modules include left and right motors and left and right angle sensors, which are both connected to the controller. The left and right angle sensors are used to detect the left and right angles of the left and right motors and send them to the controller, which performs closed-loop control on the left and right motors.

[0014] According to the tennis serving robot provided by the embodiment of the present invention, it also includes a user positioning device, which communicates with a controller. The controller enters one or more of a custom serving mode, a return running mode, a follow-up battle mode and a smart step comparison mode in response to the user position information detected by the user positioning device, wherein the custom serving mode is configured to perform a custom serve based on the user's custom serving parameters, the return running mode is configured to start serving when it is determined based on the information detected by the user positioning device that the user has run to the restoration point area, the follow-up battle mode is configured to determine the single ball parameters of the next serve based on the information detected by the user positioning device, and the smart step comparison mode is configured to compare the running information detected by the user positioning device with the expected running information template; wherein the single ball parameters include one or more of serving speed, serving rotation type, serving rotation speed, arc, left and right direction and single ball interval.

[0015] Furthermore, the user positioning device includes a main base station, a secondary base station and a tag, wherein the main base station is arranged on the robot body, the secondary base station is arranged on the ball net, and the tag is arranged on the user;

[0016] The tag and the primary base station as well as the tag and the secondary base station all use electromagnetic wave flight time to achieve distance measurement, and calculate the tag position based on triangulation positioning to obtain the user's location information.

[0017] Furthermore, when the number of the secondary base station is one, the two solutions of the horizontal coordinate of the tag in the coordinates of the tennis court are:

[0018]

[0019] The two solutions for the ordinate of the label in the coordinates of the tennis court are:

[0020]

[0021] In the formula, parameters A, B, and C are:

[0022]

[0023] x0 and y0 represent the horizontal and vertical coordinates of the primary base station on the tennis court, respectively; x1 and y1 represent the horizontal and vertical coordinates of the secondary base station on the tennis court, respectively; t1 and x t2They represent the two solutions of the horizontal coordinates of the label in the coordinates of the tennis court, y t1 and t2 They represent the two solutions of the vertical coordinates of the label in the coordinates of the tennis court. Both t1 and t2 represent intermediate variables.

[0024]

[0025] D0 represents the two-dimensional distance between the tag and the primary base station, and D1 represents the two-dimensional distance between the tag and the secondary base station.

[0026] Furthermore, when there are more than two secondary base stations, the least square method is used to solve the over-constrained distance equation group, and the coordinates of the tag on the tennis court are obtained as follows:

[0027]

[0028] In the formula, x t and t They represent the horizontal and vertical coordinates of the label on the tennis court respectively. The cosine theorem coefficient matrix M and the cosine theorem constant matrix P are:

[0029]

[0030] In the formula, (x i ,y i ) represents the coordinates of the ith secondary base station on the tennis court, D i represents the two-dimensional distance between the tag and the i-th secondary base station.

[0031] Furthermore, in the follow-up battle mode, the user positioning device is configured to locate the user at a period T. p Get the user's location information and transmits it to the controller, which first uses the offset mode and offset distance x configured by the user in the follow-up battle mode. o Get the expected angle of the left and right modules, the expected angle θ of the left and right modules in the case of forehand offset dy for in, is the placement of the robot on the court, and the expected angle θ of the left and right modules in the case of backhand offset dy for

[0032] The robot body obtains the actual angle θ of the current left and right modules ay and speed Combined with the remaining time T ly Calculate the movement angle θ of the left and right modules of this serve ymin and θ ymax ;

[0033] Compare the expected angles θ of the left and right modules dy and the motion angle θ ymin and θ ymax When θ dy <θ ymin , the target angle of the left and right modules 15 of the serving robot is θ ymin ; When θ dy >θ ymax , the target angle of the left and right modules of the serving robot is θ ymax ; When θ ymax ≥θ dy ≥θ ymin , the target angle of the left and right modules of the serving robot is θ dy .

[0034] Furthermore, in the smart step comparison mode, the interval between two serves of the serving robot is taken as an analysis period, and each serve is defined as having an expected starting area and a hitting area, and the serving time of the serving robot is defined as The time when the user runs out of the expected starting area is The time when the user enters the hitting area is The time it takes for the user to enter the expected starting area for the next serve after hitting the ball is The next serve time is Get four evaluation times, the four evaluation times include: first waiting time Startup time Return time and the second waiting time

[0035] For the first waiting time Less than This means that the user does not have enough time to prepare for the shot. Less than It means that the user's running and hitting ability meets the standard, otherwise the running and hitting ability is insufficient; for the return time Less than It means that the user's running ability to return to the position meets the standard, otherwise the running ability to return to the position is insufficient; for the second waiting time Less than This means that the user does not have enough time to prepare for the next shot.

[0036] According to a second aspect of an embodiment of the present invention, the present invention further provides a tennis serving system, which comprises the tennis serving robot and the smart racket as described above, wherein the smart racket communicates with a controller, and the controller enters one or more of a custom serving mode, a return running mode, a follow-up battle mode, a smart step comparison mode, a smart racket mode, and a simulated battle mode in response to the motion trajectory of the smart racket and the collision information between the tennis ball and the smart racket, wherein the custom serving mode is configured to perform a custom serve based on the user's custom serving parameters, and the return running mode is configured to perform a custom serve based on the user's custom serving parameters. The serve is initiated when the information detected by the positioning device determines that the user has run to the restoration point area, and the single-ball parameters of the next serve are determined based on the information detected by the user positioning device. The smart step comparison mode is configured to compare the running information detected by the user positioning device with the expected running information template. The smart racket mode is configured to initiate the tennis serving robot to serve when it is determined that the user's serve is successful based on the collision information between the smart racket and the tennis ball. The simulated battle mode is configured to use the information detected by the user positioning device and the collision information between the smart racket and the tennis ball to adjust the single-ball parameters and combined parameters of the tennis serve in real time.

[0037] According to the tennis serving system provided by an embodiment of the present invention, the smart racket includes a racket body, a rubber cover and a detection module, wherein the detection module is fixed to the end of the handle in the racket body through the rubber cover, and an inertial measurement unit is provided in the detection module, and the inertial measurement unit is used to measure the motion trajectory of the racket body and the collision information between the tennis ball and the racket body.

[0038] According to the above specific embodiments of the present invention, it can be known that at least the following beneficial effects are achieved: the tennis serving robot provided by the present invention can diversify the serving modes by setting custom serving modes, meet personalized needs, and make the interaction more intuitive and simple; through the closed-loop control of the ball squeezing module, the consistency of the tennis landing point and the switching control can be improved, and the serving routine can be improved; the present invention can improve the capabilities and application scenarios of the tennis serving robot by setting a robot body, a user positioning system and a smart racket, and setting a custom serving mode, a return running mode, a follow-up battle mode, a smart step comparison mode, a smart racket mode and a simulated battle mode in the robot body; the present invention can open the hatch when a fault occurs by setting a hatch module, making equipment maintenance safer and more convenient.

[0039] It should be understood that the foregoing general description and the following detailed description are merely exemplary and illustrative and are not intended to limit the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings below are part of the specification of the present invention, and illustrate embodiments of the present invention. The accompanying drawings together with the description of the specification are used to explain the principle of the present invention.

[0041] Figure 1 A schematic diagram of the overall structure of a tennis serving robot provided in a specific embodiment of the present invention;

[0042] Figure 2 One of the schematic diagrams of the internal structure of a robot body in a tennis serving robot provided in a specific embodiment of the present invention;

[0043] Figure 3 The second schematic diagram of the internal structure of the robot body of a tennis serving robot provided in a specific embodiment of the present invention;

[0044] Figure 4 A structural block diagram of a tennis serving robot provided in a specific embodiment of the present invention;

[0045] Figure 5 A flowchart of a tennis serving robot opening a hatch provided by a specific embodiment of the present invention;

[0046] Figure 6 A flowchart of a custom serving mode in a tennis serving robot provided in a specific embodiment of the present invention;

[0047] Figure 7 A flowchart of a return running mode in a tennis serving robot provided in a specific embodiment of the present invention;

[0048] Figure 8 A flowchart of a follow-up battle mode in a tennis serving robot provided in a specific embodiment of the present invention;

[0049] Fig. 9 A flowchart of a smart-step comparison mode in a tennis serving robot provided in a specific embodiment of the present invention;

[0050] Fig.10 A result block diagram of a tennis serving system provided by a specific embodiment of the present invention;

[0051] Fig.11 A flowchart of an intelligent racket mode in a tennis serving robot provided in a specific embodiment of the present invention;

[0052] Fig.12 A flowchart of a simulated battle mode in a tennis serving robot provided in a specific embodiment of the present invention.

[0053] Description of reference numerals:

[0054] 1. Robot body; 10. Ball collecting basket; 11. Controller;

[0055] 12. Ball feeding module; 121. Ball feeding motor; 122. Photoelectric sensor;

[0056] 13. Ball squeezing module; 131. Upper wheel motor; 132. Lower wheel motor; 133. Upper wheel speed sensor; 134. Lower wheel speed sensor;

[0057] 14. Pitch module; 141. Pitch motor; 142. Pitch angle sensor;

[0058] 15. Left and right modules; 151. Left and right motors; 152. Left and right angle sensors;

[0059] 16. Hatch door module; 161. Integrated electromagnet;

[0060] 2. User positioning device; 21. Main base station;

[0061] 3. Smart racket. DETAILED DESCRIPTION

[0062] In order to make the objectives, technical solutions and advantages of the embodiments of the present invention more clearly understood, the spirit of the contents disclosed by the present invention will be clearly explained with the accompanying drawings and detailed descriptions below. After understanding the embodiments of the contents of the present invention, any technician in the relevant technical field can change and modify the techniques taught by the contents of the present invention without departing from the spirit and scope of the contents of the present invention.

[0063] The exemplary embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention. In addition, the same or similar reference numerals used in the drawings and embodiments are used to represent the same or similar parts.

[0064] The terms “first”, “second”, etc. used in this document do not particularly refer to an order or sequence, nor are they used to limit the present invention. They are only used to distinguish elements or operations described with the same technical terms.

[0065] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0066] As used herein, "and / or" includes any or all combinations of the items described.

[0067] As used herein, “plurality” includes “two” and “more than two”; as used herein, “plurality groups” includes “two groups” and “more than two groups”.

[0068] Certain terms that are used to describe the invention are discussed below or elsewhere in the specification to provide additional guidance to those skilled in the art regarding the description of the invention.

[0069] The existing tennis ball serving robot's ball squeezing motor generally adopts an open-loop control system. This means that without external feedback, the system cannot automatically adjust the working state according to the actual situation, resulting in a large deviation in the landing position of each tennis ball served, that is, the consistency of the tennis ball landing point is poor, which affects the accuracy requirements during training.

[0070] The existing extruded tennis serving robot keeps the speed of its internal drive motor constant during the task, and lacks a dynamic speed adjustment mechanism. As a result, it is difficult to simulate the ever-changing serving styles in real game scenarios, for example, the ability to quickly switch between different types of spin balls (such as from topspin to backspin) is greatly limited.

[0071] Existing extruded tennis serving robots are usually equipped with only a few fixed serving schemes pre-set by the manufacturer, with little room for users to choose from, and the preset modes are too simple. This modular design is difficult to meet the needs of personalized training, especially when conducting special exercises for specific skills or strategies.

[0072] Existing extruded tennis serving robots generally lack a feedback system that allows users to interact with them well, and lack an effective interaction mechanism. This requires operators to try many times to find the most suitable configuration when adjusting the settings to match their personal skill level, greatly reducing training efficiency.

[0073] In addition, when encountering common problems such as ball jamming, existing extruded tennis serving robots often require users to disassemble some components for cleaning or repair. The process is complicated and time-consuming, which brings many inconveniences to daily use.

[0074] Although the existing extrusion-type tennis serving robot can assist tennis enthusiasts and professional players to complete basic exercises to a certain extent, the above-mentioned defects seriously restrict the possibility of further improving the training effect. Therefore, the development of a new generation of tennis serving robots with higher intelligence and better user experience has become an urgent need for the development of the industry.

[0075] The tennis serving robot provided by the present invention responds to a user's custom serving instruction, enters a custom serving mode based on the user's custom serving instruction, and performs a custom serving according to the received custom serving parameters in the custom serving mode. The custom serving parameters include single ball parameters and combined parameters, the single ball parameters include one or more of serving speed, serving rotation type, serving rotation speed, arc, left and right direction, single ball interval, and single ball repetition number; the combined parameters include one or more of group interval, single ball switching mode, automatic stop mode and parameters, and countdown time.

[0076] like Figure 1-Figure 3 As shown, the tennis serving robot provided by the present invention includes a robot body 1 and a ball collecting basket 10, a controller 11, a ball sending module 12, a ball squeezing module 13, a pitch module 14 and a left and right module 15 arranged on the robot body 1; wherein, the ball collecting basket 10 is arranged above the ball sending module 12, and the ball sending module 12, the ball squeezing module 13, the pitch module 14 and the left and right modules 15 are all connected to the controller; the ball sending module 12 is used to obtain the collected tennis balls from the ball collecting basket 10 and transport the tennis balls to the ball squeezing module 13, the ball squeezing module 13 is used to squeeze the tennis balls to achieve serving, and the pitch module 14 and the left and right modules 15 are used to adjust the up and down and left and right directions of the tennis balls squeezed by the ball squeezing module 13.

[0077] In this embodiment, the ball collecting frame 10 adopts a foldable fabric design for easy storage, and the upper sealing zipper can effectively prevent the tennis ball from falling during the movement of the tennis serving robot, which has great practical value.

[0078] In the above embodiment, the tennis serving robot provided by the present invention further includes a door module 16, which is connected to the controller 11 and is used to respond to the user's door opening and closing instructions to open or close the door.

[0079] In a specific embodiment, the ball delivery module 12 includes a ball delivery motor 121 and a photoelectric sensor 122, and both the ball delivery motor 121 and the photoelectric sensor 122 are connected to the controller 11. The photoelectric sensor 122 is arranged in the ball delivery channel to detect information about a tennis ball entering the ball delivery channel. The information about a tennis ball entering the ball delivery channel includes information such as the position and movement state of the tennis ball.

[0080] The controller 11 is used to receive signals from the photoelectric sensor 122 and control the action of the ball feeding motor 121 based on the received signals; when the photoelectric sensor 122 detects that a tennis ball enters the ball feeding channel, the controller 11 stops the ball feeding motor 121 in response to the signal sent by the photoelectric sensor 122, and restarts the ball feeding motor 121 after the tennis ball completely passes through the ball feeding channel, thereby ensuring that only one tennis ball is fed out at a time.

[0081] In a specific embodiment, the ball squeezing module 13 includes an upper wheel motor 131, a lower wheel motor 132, an upper wheel speed sensor 133 and a lower wheel speed sensor 134. The upper wheel motor 131, the lower wheel motor 132, the upper wheel speed sensor 133 and the lower wheel speed sensor 134 are all connected to the controller 11. The upper wheel speed sensor 133 and the lower wheel speed sensor 134 respectively detect the rotation speeds of the upper wheel motor 131 and the lower wheel motor 132, and send the detected rotation speeds to the controller 11. The controller 11 adjusts the rotation speeds of the upper wheel motor 131 and the lower wheel motor 132 in real time according to the received rotation speeds, completes the closed-loop control of the upper wheel motor 131 and the lower wheel motor 132, and improves the consistency of the serve.

[0082] In a specific embodiment, the pitch module 14 includes a pitch motor 141 and a pitch angle sensor 142, both of which are connected to the controller 11, and the pitch angle sensor 142 is used to detect the pitch angle of the pitch motor 141 and send it to the controller 11, and the controller 11 performs closed-loop control on the pitch motor 141. The left and right modules 15 include left and right motors 151 and left and right angle sensors 152, both of which are connected to the controller 11, and the left and right angle sensors 152 are used to detect the left and right angles of the left and right motors 151 and send them to the controller 11, and the controller 11 performs closed-loop control on the left and right motors 151.

[0083] In a specific embodiment, the door module 16 includes an integrated electromagnet 161, and the integrated electromagnet 161 is connected to the controller 11. Figure 4 As shown, the controller 11 controls the ball feeding motor 121, the upper wheel motor 131, the lower wheel motor 132 and the left and right motors 151 to stop running according to the received hatch opening command to ensure the safety during the maintenance process. Then the controller 11 controls the integrated electromagnet 161 to open the hatch to facilitate the user to clean the stuck ball or foreign objects. After the user completes the maintenance, the device can be used normally by manually closing the hatch. The entire operation process is safe and simple.

[0084] When the tennis serving robot is stuck in the ball or needs to clean foreign objects for maintenance, the provision of the hatch module 16 can provide great convenience. The user no longer needs to disassemble the robot body 1 to complete the maintenance, which is both safe and practical.

[0085] In another embodiment, Figure 5As shown, the tennis serving robot provided by the present invention also includes a user positioning device 2, which communicates with the controller 11. The controller 11 enters one or more of a custom serving mode, a return running mode, a follow-up battle mode and a smart step comparison mode in response to the user position information detected by the user positioning device 2, wherein the custom serving mode is configured to perform a custom serve based on the user's custom serving parameters, the return running mode is configured to start serving when it is determined that the user has run to the restoration point area based on the information detected by the user positioning device 2, the follow-up battle mode is configured to determine the single ball parameters of the next serve based on the information detected by the user positioning device 2, and the smart step comparison mode is configured to compare the running information such as speed, time and trajectory detected by the user positioning device 2 with the expected running information template, so as to obtain the user's running ability, whether the running meets the standard, advantages and disadvantages and other analysis results.

[0086] In a specific embodiment, the user positioning device 2 is implemented based on the UWB positioning principle, and the user positioning device 2 includes a main base station 21, a secondary base station and a tag, wherein the main base station 21 is set on the robot body 1, the secondary base station is set on the ball net, and the tag is set on the user, which can effectively reduce the deployment difficulty of the user positioning device 2. The user positioning device 2 uses the electromagnetic wave flight time to complete the distance measurement between the tag and the main base station 21 and the distance measurement between the tag and the secondary base station, and then completes the calculation of the tag position based on triangulation positioning.

[0087] The ranging principle between the tag and the primary base station 21 and the ranging principle between the tag and the secondary base station is a bilateral two-way ranging method with four messages.

[0088] Taking the distance measurement between the tag and the main base station 21 as an example, the main base station 21 actively initiates the first distance measurement message, and the tag responds. The time from the main base station 21 sending the timestamp to receiving the tag response timestamp is T r1 The time from when the tag receives the timestamp to when it sends the timestamp to the main base station 21 is T y1 After a certain period of time, the tag actively initiates a ranging message, and the main base station 21 responds to the response. The time from the tag sending the timestamp to receiving the main base station 21 response timestamp is T r2 The time from the main base station 21 receiving the timestamp to sending the timestamp to the tag is T y2 , then the flight time T f for:

[0089]

[0090] The three-dimensional distance L0 between the tag and the main base station 21 is:

[0091] L0=V*T f .

[0092] Where V represents the communication speed between the primary base station 21 and the tag, and L represents the three-dimensional distance between the tag and the secondary base station i. i The distance calculation principle between the tag and the main base station 21 is the same as above.

[0093] The user positioning device 2 supports the case where there is only one secondary base station and also supports the case where there are more than one secondary base stations. Considering that the tennis court is a plane, more attention is paid to the two-dimensional coordinates of the plane. Therefore, in either case, the three-dimensional straight-line distance needs to be projected into a two-dimensional straight-line distance. Assuming that the height of the main base station 21 is H0 and the height of the tag is H tag , the height of secondary base station i is H i , the distance between the tag and the primary base station 21 is L0, and the distance between the tag and the secondary base station i is L i , then the two-dimensional distance between the tag and the main base station The two-dimensional distance D between the tag and the secondary base station i i for:

[0094]

[0095] In the formula, i=1…n, and n represents the number of secondary base stations in the user positioning device 2 .

[0096] For the case where there is only one secondary base station, the intersection of a circle with the main base station 21 as the center and the two-dimensional distance D0 between the tag and the main base station 21 as the radius and a circle with the secondary base station as the center and the two-dimensional distance D1 between the tag and the secondary base station as the radius is the required coordinate; when the two circles do not intersect, the positioning system fails to solve; when the two circles are tangent, the tangent point is the required coordinate point; when the two circles intersect, the two intersection points may be the required coordinate points. At this time, it is necessary to select according to the application scenario. For example, when the main base station 21 is installed on the robot body 1 and the secondary base station is installed just above the doubles sideline on the right side of the net, the coordinate point on the upper left of the robot body 1 is selected as the user's positioning coordinate, because the user's range of motion when playing can only be located in the opposite half of the robot body 1. The coordinate calculation method obtained based on the above principle is as follows. Assume that the coordinates of the main base station 21 on the tennis court are (x0, y0), the coordinates of the secondary base station on the tennis court are (x1, y1), and the coordinates of the tag to be determined on the tennis court are (x t ,y t ), then the constraint equation is as follows:

[0097]

[0098] Arrange and eliminate to get x t The quadratic equation system is:

[0099]

[0100] Where t1 and t2 are intermediate variables, respectively expressed as:

[0101]

[0102] Solve the quadratic equation to obtain two solutions for the label's horizontal coordinate Further obtain two solutions for the label ordinate Taking advantage of the fact that the user's range of motion when playing the ball can only be in the half court opposite to the robot body 1, (x t1 ,y t1 ) and (x t2 ,y t2 ) are substituted into the (x, y) in the inequality x1-t1(y-y1)>x. The label coordinate value that satisfies the inequality is the desired one.

[0103] When the number of secondary base stations is more than two, the distance measurement between the tag and the primary base station 21 and the secondary base station is over-constrained. Therefore, the following least squares formula is used to solve the coordinates of the tag on the tennis court:

[0104]

[0105] In the formula, the cosine theorem coefficient matrix M and the cosine theorem constant matrix P are respectively:

[0106]

[0107] In the formula, (x i ,y i ) represents the coordinates of the ith secondary base station on the tennis court, D i represents the two-dimensional distance between the tag and the i-th secondary base station.

[0108] In a specific embodiment, based on the information detected by the upper wheel speed sensor 133, the lower wheel speed sensor 134, the pitch angle sensor 142, the left and right angle sensor 152, the photoelectric sensor 122 and the IMU, a serving mode can be customized in the controller 11.

[0109] like Figure 6 As shown, the parameters that need to be configured in the custom serving mode include single ball parameters and combined parameters, wherein the single ball parameters include serving speed, serving rotation type (topspin, backspin and no spin), rotation speed, arc, left and right direction, single ball interval and single ball repetition times; the combined parameters include group interval, single ball switching mode (sequential, random, etc.), automatic stop mode and parameters (infinite, timed, fixed number and fixed group mode) and countdown time. Several single ball parameters and one combined parameter constitute a training routine.

[0110] The present invention converts the serving speed, serving rotation type and serving rotation speed into the upper wheel rotation speed and the lower wheel rotation speed of the ball squeezing wheel through the contact model between the ball squeezing wheel of the ball squeezing module 13 and the tennis ball. The specific implementation process is as follows:

[0111] Set the serve spin type and serve spin speed w s Merge into one parameter w n , when the serve rotation type is topspin, w n =-w s , w n When the value is less than 0, the serve rotation type is no spin w n =0, when the serve spin type is backspin, w n =w s , w n A value greater than 0.

[0112] Since the ball squeezing wheel adopts speed closed-loop control, the speed and rotation speed of the tennis ball at different up and down squeezing speeds are obtained by a 1000fps high-speed camera, and the tennis ball speed v is obtained by linear fitting. n and rotation w n With the upper wheel speed v u and the lower wheel speed v d The expression k u , k d , k c ,q u ,q d and q c are the linear fitting coefficients respectively.

[0113] The upper wheel speed v is obtained by elimination u and the lower wheel speed v d With tennis ball speed v n and rotation w n The relationship is Thus, the desired rotation speeds of the upper wheel motor 131 and the lower wheel motor 132 of the ball squeezing module 13 are obtained.

[0114] Combined with the pitch module 14 controlled by arc, the left and right modules 15 controlled by left and right orientation, and the ball delivery module 12 controlled by single ball interval and inter-group interval, the motion control of the tennis serving robot is realized. At the same time, based on the placement position of the tennis serving robot in the field, the left and right joint angles of the left and right modules 15, the pitch joint angles of the pitch module 14, and the structural dimensions of the robot body 1, the initial position of the tennis serve can be obtained by using the robot's forward kinematics, and the flight trajectory of the tennis ball before landing can be obtained by analyzing the initial state of the tennis ball (initial position, serving speed, serving rotation type, and serving rotation speed) and the dynamic model of the tennis ball flying in the air. Based on the flight trajectory of the tennis ball, the trajectory state (netting and out of bounds, etc.), landing point, net crossing height, and maximum height can be obtained.

[0115] The specific calculation process is:

[0116] With the midpoint of the tennis court net as the center, the right side of the robot body 1 as the x direction, and the forward direction as the y direction, the world coordinate system Ow is established, and the placement position of the robot body 1 in the venue is P r (x r ,y r ), defined as the coordinate value of the rotation axis of the left and right modules 15 projected on the tennis court in the world coordinate system, so that the conversion matrix between the base coordinate system of the robot body 1 and the world coordinate system is obtained as follows:

[0117] According to the configuration design of the tennis serving robot, the conversion matrix of the left and right modules 15 is where θ y is the angle of the left and right motion joints, and the conversion matrix of the pitch module 14 is where θ p is the angle of the pitch motion joint, L1, L2 and L3 represent the structural offset dimensions of the pitch joint and the left and right joints of the tennis serving robot respectively.

[0118] The transformation matrix of the ball squeezing module 13 relative to the world coordinate system can be obtained by using the continuous multiplication rule of the coordinate transformation matrix:

[0119] Further obtain the initial position information of the tennis ball machine at the moment of serving Initial velocity information and initial rotation information

[0120] Using the dynamic iteration model of a tennis ball flying in the air, all trajectory points before the tennis ball collides with the tennis court ground can be obtained based on the initial position, velocity, and rotation information of the tennis ball. The dynamic iteration model is described as follows:

[0121] The acceleration of a tennis ball flying through the air is expressed as:

[0122] where k z is the air resistance coefficient, k m is the Magnus force coefficient, is the acceleration of the tennis ball at the kth iteration, is the speed of the tennis ball at the kth iteration, ||V k || is the speed of tennis ball The modulus, wx, wy and wz are the rotation speeds of the tennis ball in the x, y and z directions, which remain approximately unchanged during the flight, and g is the acceleration due to gravity.

[0123] Integrating the acceleration gives the speed of the tennis ball. and location Where dt is the iteration time step.

[0124] With flight track points You can get the landing point of the tennis ball (z k When x is less than 0 k and k The value of the landing point) and the height of the net (y k When z is greater than 0 for the first time k The value of is the height over the net), and the trajectory status (ball in, out of bounds, and in) is further obtained. The entire trajectory points before the landing point can be reconstructed in three dimensions to obtain a simulation animation, which changes in real time as the serving parameters are adjusted.

[0125] The entire trajectory points before the landing point can be displayed on the terminal, thereby realizing the animation simulation display of customized serve parameter adjustment, which greatly facilitates the user's parameter adjustment and what you see is what you get.

[0126] In a specific embodiment, Figure 7 As shown, the tennis serving robot can be set to a return running mode. In this mode, the robot body 1 determines that the user has run to the restoration point area based on the information detected by the user positioning device 2 before starting to serve. The serving information (single ball parameters and combination parameters) and the restoration point area (the center coordinates of the restoration point area) can be obtained through the tennis skills and tactics configured by the user. Area width wa, area length la, delay time Tad), the user positioning device 2 obtains the user's location information in real time. When the user's location information enters the restoration point area for the first time, if the ball delivery module 12 of the robot body 1 is not delivering the ball, the ball delivery module 12 starts delivering the ball. If the ball delivery module 12 of the robot body 1 is already delivering the ball, the serving robot does not make adjustments and continues the serving business logic. When the user's location is not entering the restoration point area for the first time, the judgment method for entering the restoration point area for the first time is described as follows:

[0127] Assume the user's coordinates are When x ac-wa / 2≤x h ≤x ac +wa / 2 and y ac -la / 2≤y h ≤y ac +la / 2 are satisfied at the same time, the user's location is determined to be within the restore point area, otherwise it is determined to be outside the restore point area. When the user's location is outside the restore point area N times in a row, it is determined that the user's location is far away from the restore point area to filter out false triggers caused by the fluctuation error of the positioning system. The first entry into the restore point area means that the user's location is within the restore point area at the current moment, and the user's status at the previous moment was far away from the restore point area.

[0128] At this time, if the ball delivery module 12 of the robot body 1 is not delivering the ball, the ball squeezing module 13, the pitch module 14 and the left and right modules 15 start the serve preparation, otherwise the serving robot does not make any adjustments and continues the serving business logic. The tennis court is relatively large. In daily training, the user usually returns to a reasonable position on the court after a hitting action to cope with the next shot. The user needs to independently set the time interval between two serves to adapt to himself, and it cannot be changed in this process. The return running mode of the present invention can adapt to the running ability of the user. The serving robot starts serving only when the user runs to the designated area. The faster the user runs, the shorter the serving interval is, and the slower the user runs, the longer the serving interval is, realizing an intelligent serving mode with adaptive serving frequency.

[0129] In a specific embodiment, the tennis serving robot can be set to a follow-up battle mode, such as Figure 8 As shown, the user positioning device 2 obtains the user's position information in real time, thereby obtaining the user's running ability, and realizes the adaptive motion control of the serving robot by combining the driving ability of the serving robot and the tennis skills and tactics configured by the user. In daily tennis training, a large number of varied serves are required to mobilize users. The follow-up battle mode of the present invention can realize serving by following the user at the venue position, and realizes an intelligent serving mode with adaptive serving point, speed and rotation.

[0130] Taking the baseline pull-up training as an example, the specific process is as follows:

[0131] The serving robot receives the serving parameters (single ball parameters and combined parameters) and serves at a normal fixed frequency. However, in this mode, the angles of the left and right modules 15 are adjusted in real time based on the user positioning device 2. After startup, the user positioning device 2 obtains the user's position information at a period Tp. The data is transmitted to the controller 11 through the serial port. The controller 11 first uses the offset mode (forehand offset, backhand offset and random offset) and the offset distance x configured by the user in the follow-up battle mode. o Obtain the desired angles of the left and right modules 15, the desired angles of the left and right modules 15 in the case of forehand offset in, The placement position of the robot body 1 on the court, and the expected angles of the left and right modules 15 in the case of backhand offset The random offset is to obtain the desired angle of the left and right modules 15 in a random situation of the current forehand offset or the backhand offset.

[0132] Then, the serving robot obtains the actual angle θ of the current left and right modules 15 ay and speed Combined with the remaining time T ly Calculate the reachable motion angle θ of the left and right modules 15 for this serve ymin and θ ymax Next, compare the desired angles θ of the left and right modules 15 dy and the achievable motion angle θ ymin and θ ymax When θ dy <θ ymin , the target angle of the left and right modules 15 of the serving robot is θ ymin , when θ dy >θ ymax , the target angle of the left and right modules 15 of the serving robot is θ ymax , when θ ymax ≥θ dy ≥θ ymin , the target angle of the left and right modules 15 of the serving robot is θ dy , thus achieving the serve following the user's position on the court, and the landing point changes more intelligently.

[0133] In a specific embodiment, the tennis serving robot can be set to a smart step comparison mode, such as Fig. 9 As shown, based on tennis skills and tactics, the user's expected running information (speed, time, trajectory, etc.) is collected in advance through the user positioning device 2 as a template. The user obtains the actual running information through the user positioning device 2 and compares it with the template, thereby obtaining the user's running ability, whether the running meets the standard, advantages and disadvantages, and other analysis results; the specific method is described as follows:

[0134] Taking the running time as an example, the interval between two serves of the serving robot is taken as an analysis period. It is defined that each serve has an expected starting area (similar to the return run) and a hitting area (there is landing point information in the simulation animation). The serving time of the serving robot is defined as The time when the user runs out of the expected starting area is The time when the user enters the hitting area is The time it takes for the user to enter the expected starting area for the next serve after hitting the ball is The next serve time is Thus, four evaluation times can be obtained, the first waiting time Startup time Return time and the second waiting time For a fixed training routine, each of the four evaluation times has an expected value. Less than This means that the user does not have enough time to prepare for the shot. Less than This means that the user's running and hitting ability meets the standard. Otherwise, the running and hitting ability is insufficient, and the return time Less than This means that the user's running ability to return to the position meets the standard. Otherwise, the running ability to return to the position is insufficient. Less than In addition, the state feedback and analysis can also be performed for the failure to enter the expected starting area and hitting area, and the feedback and evaluation of the training results can be achieved by comparing with the template parameters.

[0135] Based on the tennis serving robot provided by the present invention, Fig.10 As shown, the present invention also provides a tennis serving system, which includes a tennis serving robot, a user positioning device 2 and an intelligent racket 3. Among them, the tennis serving robot and the user positioning device 2 use wired serial communication, and the tennis serving robot and the intelligent racket 3 use wireless communication, which can be wireless Bluetooth communication. The user positioning device 2 is used to detect the user's location information and send it to the tennis serving robot, and the intelligent racket 3 is used to measure the motion trajectory of the racket body and the collision information between the tennis ball and the racket body and send it to the tennis serving robot. The tennis serving robot sets the serving mode, the return running mode, the follow-up battle mode, the smart step comparison mode, the intelligent racket mode and the simulated battle mode according to the received information.

[0136] In a specific embodiment, the smart racket 3 includes a racket body, a rubber sleeve and a detection module, wherein the detection module is fixed to the end of the handle in the racket body through the rubber sleeve, and the rubber sleeve can adapt to handles of different thicknesses. An IMU (Inertial Measurement Unit) is provided in the detection module, and the IMU is used to measure the motion trajectory of the racket body and the collision information between the tennis ball and the racket body.

[0137] In a specific embodiment, Fig.11As shown, the tennis serving robot can be set to the intelligent racket mode. In the intelligent racket mode, the intelligent racket 3 obtains the racket's three-dimensional acceleration and three-dimensional angular velocity information in real time. This information can be used to detect the hitting and hitting state (hitting time, hitting speed, racket posture and action category, etc.). Combined with the incoming ball information (that is, the serving information of the tennis serving robot), the user's return ball information can be obtained. Finally, the motion control of the tennis serving robot is realized through the tennis serving robot's serving information, tennis skills and tactics, and the user's return ball information. The specific implementation method is described as follows:

[0138] The smart racket 3 is connected to the tennis serving robot via Bluetooth. The IMU data results processed and analyzed by the smart racket 3 are sent to the controller 11 via Bluetooth. The controller 11 determines the parameters of the next serve (such as single ball parameters and combination parameters, etc.) based on the current serving information, tennis skills and tactics (user configuration or AI) and the current user return information.

[0139] Serving connection is an important part of tennis training, which trains the user's ability to receive and receive serves. The specific description is as follows: the user serves first, then the opponent receives the serve, and then the user receives the serve. The tennis serving robot of the present invention can detect the user's serving information and respond to a serve to simulate receiving and receiving in time, thereby achieving the effect of training serving connection. The specific implementation method is described as follows:

[0140] The smart racket 3 analyzes the IMU data to obtain the user's serve information (serve type, serve strength and serve time, etc.) and informs the controller 11 through Bluetooth communication. The controller 11 uses the established strategy (tennis skills and tactics) to automatically adjust the single ball parameters (serve speed, rotation type and speed) and combination parameters of the next serve to simulate the serve reception in actual combat.

[0141] In a specific embodiment, the tennis serving robot can be set to a simulated battle mode, as shown in the flow chart. Fig.12As shown, the user positioning device 2 obtains the user's running information, and transmits the user's running information to the controller 11 through serial communication, and the intelligent racket 3 transmits the user's hitting information to the serving robot controller 11 through Bluetooth. The two external information and the skills and tactics of tennis (user-configured strategies or AI) are used to adjust the single ball parameters and combined parameters of tennis serving in real time. The serving robot controller 11 further converts the serving single ball parameters and combined parameters into the upper and lower wheel speed control targets of the ball squeezing module 13, the target angles of the motors of the pitch module 14 and the left and right modules 15, and the start and stop timing of the motor of the ball delivery module 12, thereby achieving the target serve. The tennis serving robot changes the serve in real time, which is more intelligent and closed-loop than the traditional fixed-rule serve. This system can effectively simulate the full link of tennis, which observes the running position and characteristics of the user and the hitting information to make a return strategy, and can realize an intelligent tennis serving robot that simulates the battle.

[0142] Specifically, the smart racket 3 detects the information and state of the tennis ball after the user hits the tennis ball, obtains the incoming ball trajectory parameters through animation simulation, adjusts the serving parameters of the serving robot, and realizes the serve in response to the incoming ball, and obtains the serve trajectory through animation simulation, and obtains the user's running information in combination with the user positioning device 2, and utilizes the encounter motion principle to obtain the trajectory state (intercept, hit the ball before the highest point of the rebound, and hit the ball after the highest point of the rebound), position, speed and rotation of the user when hitting the ball this time, as well as the action information of the user hitting the tennis ball by the smart racket 3 to obtain the information and state of the tennis ball after the user hits the ball this time, obtains the incoming ball trajectory parameters through animation simulation, adjusts the serving parameters of the serving robot, and realizes the serve in response to the incoming ball, and this cycle is repeated to realize the simulated battle.

[0143] The above-described embodiments of the present invention may be implemented in various hardware, software coding, or a combination of the two. For example, embodiments of the present invention may also be program codes for executing the above-described methods in a digital signal processor. The present invention may also relate to various functions performed by a computer processor, a digital signal processor, a microprocessor, or a field programmable gate array. The above-described processor may be configured according to the present invention to perform specific tasks, which are accomplished by executing machine-readable software code or firmware code that defines the specific methods disclosed by the present invention. The software code or firmware code may be developed into different programming languages ​​and different formats or forms. The software code may also be compiled for different target platforms. However, the different code styles, types, and languages ​​of the software code for performing tasks according to the present invention and other types of configuration codes do not depart from the spirit and scope of the present invention.

[0144] The above description is only an illustrative specific implementation manner of the present invention. Without departing from the concept and principle of the present invention, any equivalent changes and modifications made by those skilled in the art should fall within the scope of protection of the present invention.

Claims

1. A tennis serving robot, characterized in that: In response to the user's customized serving instruction, the customized serving mode is entered based on the user's customized serving instruction, and a customized serving is performed according to the received customized serving parameters in the customized serving mode.

2. The tennis serving robot according to claim 1, characterized in that: It includes a robot body and a ball collecting basket, a controller, a ball sending module, a ball squeezing module, a pitch module and a left and right module arranged on the robot body; wherein the ball collecting basket is arranged above the ball sending module, and the ball sending module, the ball squeezing module, the pitch module and the left and right modules are all connected to the controller; the ball sending module is used to obtain the collected tennis balls from the ball collecting basket and transport the tennis balls to the ball squeezing module, the ball squeezing module is used to squeeze the tennis balls to realize serving, and the pitch module and the left and right modules are used to adjust the up and down and left and right directions of the tennis balls squeezed by the ball squeezing module.

3. The tennis serving robot according to claim 2, characterized in that: It also includes a door module, which is connected to the controller and is used to respond to the user's door opening and closing instructions to open or close the door.

4. The tennis serving robot according to claim 2, characterized in that: The ball delivery module includes a ball delivery motor and a photoelectric sensor, both of which are connected to the controller, and the photoelectric sensor is arranged in the ball delivery channel to detect information that a tennis ball enters the ball delivery channel; The controller is used to receive a signal from the photoelectric sensor and control the action of the ball feeding motor based on the received signal; when the photoelectric sensor detects that a tennis ball enters the ball feeding channel, the controller stops the ball feeding motor in response to the signal sent by the photoelectric sensor, and restarts the ball feeding motor after the tennis ball completely passes through the ball feeding channel, thereby ensuring that only one tennis ball is fed out at a time.

5. The tennis serving robot according to claim 2, characterized in that: The ball squeezing module includes an upper wheel motor, a lower wheel motor, an upper wheel speed sensor and a lower wheel speed sensor, and the upper wheel motor, the lower wheel motor, the upper wheel speed sensor and the lower wheel speed sensor are all connected to the controller, the upper wheel speed sensor and the lower wheel speed sensor respectively detect the rotation speed of the upper wheel motor and the lower wheel motor, and send the detected rotation speed to the controller, and the controller adjusts the rotation speed of the upper wheel motor and the lower wheel motor in real time according to the received rotation speed.

6. The tennis serving robot according to claim 5, characterized in that: The upper wheel speed v of the squeezing wheel is obtained according to the serving speed, the serving rotation type and the serving rotation speed. u and the lower wheel speed v d They are: Among them, k u , k d , k c ,q u ,q d and q c They represent the linear fitting coefficients, v n represents the speed of the tennis ball, w n represents the serve rotation speed vector, which is composed of the serve rotation type and the serve rotation speed magnitude w s The combined parameters.

7. The tennis serving robot according to claim 2, characterized in that: The pitch module includes a pitch motor and a pitch angle sensor, both of which are connected to the controller, and the pitch angle sensor is used to detect the pitch angle of the pitch motor and send it to the controller, and the controller performs closed-loop control on the pitch motor; The left and right modules include left and right motors and left and right angle sensors, which are both connected to the controller. The left and right angle sensors are used to detect the left and right angles of the left and right motors and send them to the controller, which performs closed-loop control on the left and right motors.

8. The tennis serving robot according to claim 1, characterized in that: It also includes a user positioning device, which communicates with a controller. The controller enters one or more of a custom serving mode, a return running mode, a follow-up battle mode and a smart step comparison mode in response to the user position information detected by the user positioning device, wherein the custom serving mode is configured to perform a custom serve based on the user's custom serving parameters, the return running mode is configured to start serving when it is determined based on the information detected by the user positioning device that the user has run to the restoration point area, the follow-up battle mode is configured to determine the single ball parameters of the next serve based on the information detected by the user positioning device, and the smart step comparison mode is configured to compare the running information detected by the user positioning device with the expected running information template; wherein the single ball parameters include one or more of serving speed, serving rotation type, serving rotation speed, arc, left and right direction and single ball interval.

9. The tennis serving robot according to claim 8, characterized in that: The user positioning device includes a main base station, a secondary base station and a tag, wherein the main base station is arranged on the robot body, the secondary base station is arranged on the ball net, and the tag is arranged on the user; The tag and the primary base station as well as the tag and the secondary base station all use electromagnetic wave flight time to achieve distance measurement, and calculate the tag position based on triangulation positioning to obtain the user's location information.

10. The tennis serving robot according to claim 9, characterized in that: When the secondary base station is set to one, the two solutions of the horizontal coordinate of the tag in the coordinates of the tennis court are: The two solutions for the ordinate of the label in the coordinates of the tennis court are: In the formula, parameters A, B, and C are: In the formula, x0 and y0 represent the horizontal and vertical coordinates of the primary base station on the tennis court, respectively; x1 and y1 represent the horizontal and vertical coordinates of the secondary base station on the tennis court, respectively; t1 and x t2 They represent the two solutions of the horizontal coordinates of the label in the coordinates of the tennis court, y t1 and t2 They represent the two solutions of the vertical coordinates of the label in the coordinates of the tennis court. Both t1 and t2 represent intermediate variables. Where D0 represents the two-dimensional distance between the tag and the primary base station, and D1 represents the two-dimensional distance between the tag and the secondary base station.

11. The tennis serving robot according to claim 9, characterized in that: When there are more than two secondary base stations, the least square method is used to solve the over-constrained distance equation group, and the coordinates of the tag on the tennis court are obtained as follows: In the formula, x t and t They represent the horizontal and vertical coordinates of the label on the tennis court respectively. The cosine theorem coefficient matrix M and the cosine theorem constant matrix P are: In the formula, (x i ,y i ) represents the coordinates of the ith secondary base station on the tennis court, D i represents the two-dimensional distance between the tag and the i-th secondary base station.

12. The tennis serving robot according to claim 8, characterized in that: In the follow-up battle mode, the user positioning device is set to a period T p Get the user's location information and transmits it to the controller, which first uses the offset mode and offset distance x configured by the user in the follow-up battle mode. o Get the expected angle of the left and right modules, the expected angle θ of the left and right modules in the case of forehand offset dy for in, is the placement of the robot on the court, and the expected angle θ of the left and right modules in the case of backhand offset dy for The robot body obtains the actual angle θ of the current left and right modules ay and speed Combined with the remaining time T ly Calculate the movement angle θ of the left and right modules of this serve ymin and θ ymax ; Compare the expected angles θ of the left and right modules dy and the motion angle θ ymin and θ ymax When θ dy <θ ymin , the target angle of the left and right modules of the serving robot is θ ymin ; When θ dy >θ ymax , the target angle of the left and right modules 15 of the serving robot is θ ymax ; When θ ymax ≥θ dy ≥θ ymin , the target angle of the left and right modules of the serving robot is θ dy .

13. The tennis serving robot according to claim 8, characterized in that: In the smart step comparison mode, the interval between two serves of the serving robot is taken as an analysis period, and each serve is defined as having an expected starting area and a hitting area, and the serving time of the serving robot is defined as T. s k , the time when the user runs out of the expected start area is The time when the user enters the hitting area is The time it takes for the user to enter the expected starting area for the next serve after hitting the ball is The next serve time is Get four evaluation times, the four evaluation times include: first waiting time Startup time Return time and the second waiting time For the first waiting time Less than This means that the user does not have enough time to prepare for the shot. Less than It means that the user's running and hitting ability meets the standard, otherwise the running and hitting ability is insufficient; for the return time Less than It means that the user's running ability to return to the position meets the standard, otherwise the running ability to return to the position is insufficient; for the second waiting time Less than This means that the user does not have enough time to prepare for the next shot.

14. A tennis serving system, characterized in that: The invention comprises a tennis serving robot and a smart racket as claimed in any one of claims 8 to 13, wherein the smart racket communicates with a controller, and the controller enters one or more of a custom serving mode, a return running mode, a follow-up battle mode, a smart step comparison mode, a smart racket mode and a simulated battle mode in response to the motion trajectory of the smart racket and the collision information between the tennis ball and the smart racket, wherein the custom serving mode is configured to perform a custom serve based on a user's custom serving parameters, the return running mode is configured to start serving when it is determined based on information detected by the user positioning device that the user has run to a restore point area, and to determine a single ball parameter of the next serve based on information detected by the user positioning device, the smart step comparison mode is configured to compare the running information detected by the user positioning device with an expected running information template, the smart racket mode is configured to start the tennis serving robot to serve when it is determined based on the collision information between the smart racket and the tennis ball that the user has successfully served, and the simulated battle mode is configured to adjust the single ball parameter and the combination parameter of the tennis serve in real time using the information detected by the user positioning device and the collision information between the smart racket and the tennis ball.

15. The tennis ball serving system according to claim 14, wherein: The smart racket includes a racket body, a rubber cover and a detection module, wherein the detection module is fixed to the end of the handle in the racket body through the rubber cover, and an inertial measurement unit is arranged in the detection module, and the inertial measurement unit is used to measure the motion trajectory of the racket body and the collision information between the tennis ball and the racket body.

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