Multi-diameter multi-ball pressure self-adaptive double-wheel serving robot and control method thereof

Abstract

A multi-diameter multi-ball pressure self-adaptive double-wheel ball launching robot and a control method thereof, the robot mainly comprises: a channel module, which automatically adapts to the elastic deformation of different ball diameters and ball pressures by using the gradual structure inside the channel and the flexible guide surface; a ball extruding module cooperates with a lifting module to form a double-wheel extruding ball launching structure; a left-right pitch joint module is used to drive the adjustment of the pitch angle and left-right turning; and the lifting module dynamically compensates the double-wheel spacing and the ball launching height according to the changes of the ball diameter and the ball pressure. The robot realizes the non-damage adaptation of various diameters and ball pressure balls and the effective locking of the lifting mechanism during extruding ball launching by using the self-adaptive ball launching channel module and the trapezoidal screw self-locking lifting adjustment module, so as to realize the high-stable, high-compatible and non-damage ball launching effect.

Description

Technical Field

[0001] This invention relates to the field of intelligent sports training equipment technology, and in particular to a multi-ball diameter, multi-ball pressure adaptive dual-wheel serving robot and its control method. Background Technology

[0002] Currently available ball-serving robots generally suffer from the following technical shortcomings, making them unable to meet the needs of multi-category, high-precision training:

[0003] Poor compatibility between ball diameter and ball pressure: The existing ball-serving robots have a fixed wheel spacing, which can only adapt to a single size of ball. They cannot cover tennis balls, peak balls, baseballs and other balls with different diameters such as 65±2mm and 70±2mm. Furthermore, they cannot accommodate the elastic deformation differences of balls with different pressures, which can easily lead to problems such as ball jamming, weak ball release, disordered trajectory and even ball damage. This limits the applicable scenarios of the equipment and increases training costs.

[0004] Lack of adaptive channel posture: When adjusting the pitch angle, the traditional fixed ball delivery channel cannot dynamically match the tangential position of the serving wheel, resulting in fluctuations in the initial velocity of the ball and deviations in the contact angle, which affects the consistency of the serving trajectory and further reduces the training effect.

[0005] It lacks an automatic spacing adjustment function and does not employ a transmission structure with self-locking capability. Even the few models with manual coarse adjustment suffer from low adjustment accuracy and cumbersome operation. Furthermore, at the moment of ball compression during the serve, the lifting mechanism is easily displaced by the ball's reaction force, leading to unstable serves.

[0006] Existing equipment typically uses a fixed spacing, with pitch angle adjustment being independently controlled and unrelated to spacing adjustment. This fixed spacing limits the equipment's serving ability and lacks quantitative analysis and control over the serving attributes caused by spacing. Summary of the Invention

[0007] To overcome the industry pain points of existing ball-serving robots, such as lack of automatic spacing adjustment, lack of self-locking function, poor compatibility, and unstable serving, this disclosure provides a multi-ball diameter and multi-ball pressure adaptive ball-serving robot. Through an adaptive ball delivery channel module and a trapezoidal screw self-locking lifting adjustment module, it achieves non-damaging adaptation to tennis balls, peak balls, baseballs, and balls with different pressures of 65±2mm and 70±2mm. At the same time, the self-locking effect of the trapezoidal screw ensures that the lifting mechanism remains stationary when the ball is squeezed for serving, ultimately achieving a highly stable, highly compatible, and non-damaging intelligent serving effect.

[0008] The multi-ball diameter, multi-ball pressure adaptive ball-serving robot disclosed herein mainly includes: a base module (005), a ball-supplying module (006), a channel module (004), a left and right pitch joint module (002), a ball-squeezing module (003), a lifting module (001), and a control unit, wherein:

[0009] The base module (005) serves as the basic support structure for the entire machine.

[0010] A ball-feeding module (006) is located at the feeding end of the channel module (004), and has a built-in sensing unit for real-time acquisition of ball diameter and ball pressure related parameters;

[0011] The channel module (004) includes: a ball delivery channel (402) for guiding the ball delivered by the ball supply module (006) to the double-wheel extrusion ball serving area; wherein, the bottom of the inlet end of the ball delivery channel is embedded in the arc-shaped groove on the left and right pitch support of the left and right pitch joint module (002), forming an arc-shaped sliding fit with the groove; the outlet end of the ball delivery channel is hinged to the pitch swing arm of the extrusion module (003);

[0012] The lifting module (001) and the ball extrusion module (003) are respectively provided with upper and lower ball-serving wheels, forming a double-wheel extrusion ball-serving structure;

[0013] The lifting module adjusts the distance between the two wheels and the height of the serve by adjusting the height of the upper serve wheel;

[0014] Meanwhile, the ball delivery channel is equipped with a gradient step and a flexible guide surface, and the geometric profile adopts a redundant design to adapt to the elastic deformation caused by different ball diameters and different ball pressures.

[0015] The left and right pitch joint module (002) is used to drive the ball extrusion module (003) and the channel module (004) to complete the adjustment of pitch angle and left and right steering.

[0016] The control unit is used to control the movement of the left and right pitch joints, the lifting module and the ball squeezing module according to the current ball diameter, ball pressure and the desired serving parameters to complete the serve.

[0017] Furthermore, the channel module (004) includes: a ball feeding channel (402) and a U-shaped bearing (401); wherein:

[0018] The ball delivery channel (402) is a bent tube structure with gradually changing steps on the side wall of the channel for balls with a diameter larger than the bottom surface of the channel to pass through; the channel adopts a flexible guide surface to adapt to the elastic deformation of the ball under different pressures; the bottom surface of the channel is provided with a ball center guide;

[0019] The bottom of the ball delivery channel (402) entrance end is fitted into the arc-shaped groove on the left and right pitch support (214) of the left and right pitch joint module (002) through a U-shaped bearing (401), and the curved tube of the channel module and the groove form an arc-shaped sliding fit;

[0020] The side wall of the ball feeding channel outlet is hinged to the ball feeding channel bearing (304) of the ball extrusion module (003) and the pitch swing arm (302) of the ball extrusion module (003);

[0021] The upper part of the ball delivery channel outlet is the serving wheel, and the height of the serving wheel is adjustable; the lower part is the serving wheel; within the pitch angle range of -10° to 50°, by controlling the relative height of the serving wheel, balls of various diameters output through the ball delivery channel (402) can be tangent to the wheel surface of the serving wheel (105) to obtain initial velocity.

[0022] Furthermore, the arc-shaped groove on the left and right pitch support (214) is an Archimedes spiral groove.

[0023] Furthermore, the lifting module (001) includes: a linear bearing (101), a trapezoidal lead screw nut (102), a lifting bracket (103), an upper wheel brushless motor (104), and a serving upper wheel (105); wherein:

[0024] The lifting bracket (103) rigidly supports the brushless motor (104) of the upper wheel and the serving upper wheel (105). According to the changes in ball diameter and ball pressure, it drives the serving upper wheel to move in the vertical direction to dynamically compensate for the distance between the two wheels and the serving height.

[0025] The linear bearings (101) are symmetrically arranged on the frame to provide clearance-free linear guidance for the lifting support (103);

[0026] The trapezoidal lead screw nut (102) cooperates with the trapezoidal lead screw to convert rotational motion into linear displacement. In conjunction with the servo motor and encoder, it enables minute adjustment of the distance between the two wheels. At the same time, the mechanical self-locking characteristic of the trapezoidal lead screw is used to lock the adjustment in place, ensuring that the lifting mechanism remains stationary when the ball is squeezed out.

[0027] Furthermore, the ball supply module (006) is equipped with a built-in sensing unit for real-time acquisition of parameters related to the ball diameter and ball pressure.

[0028] This disclosure also provides a method for controlling the squeeze serve of a dual-wheel serve robot based on serve attributes, which mainly includes the following steps:

[0029] Based on the set serving attributes, including the expected speed of the serving robot's serve. and desired rotation speed ,in Indicates top rotation. Indicates irrotation. Indicates backspin; solve for the control parameters of the squeeze serve, including: the rotation speed of the serve's upper roller. Next wheel speed and extrusion volume Specific methods include:

[0030] S1, constructing the extrusion volume With the maximum speed of the serve Constraints:

[0031] ,

[0032] in, and A coefficient related to the type and diameter of the ball. These are parameters related to the contact surface material and the coefficient of friction.

[0033] Then based on the expected speed To obtain a minimum value of the extrusion amount:

[0034] ;

[0035] S2, constructing extrusion volume With the maximum spin speed of the serve Constraints:

[0036] ,

[0037] in, and A coefficient related to the type and diameter of the ball. These are parameters related to the contact surface material and the coefficient of friction.

[0038] Then based on the desired rotation speed To obtain a minimum value of the extrusion amount

[0039] ;

[0040] S3, take and minimum value and judge The maximum amount of pressure that the serving robot can support for each type of ball. Size, Determined by the type of ball, if This indicates the desired speed. Expected rotational speed of chord If it cannot be achieved, then it indicates the desired speed. Expected rotational speed of chord This can be achieved; proceed to the next step of optimization.

[0041] S4, establish the constraint relationship between the serve speed and the rotation speed of the upper and lower rollers.

[0042]

[0043] In the formula, upper wheel speed Next wheel speed , For velocity transmission coefficient, These are parameters related to the friction coefficient. The diameter of the serve wheel;

[0044] At the same time, a constraint relationship is established between the serve spin speed and the rotation speed of the upper and lower rollers:

[0045]

[0046] In the formula, upper wheel speed Next wheel speed , For velocity transmission coefficient, These are parameters related to the coefficient of friction.

[0047] Construct the optimal objective function:

[0048]

[0049] In the formula, , and Weighting coefficients It is an energy function;

[0050] The required extrusion control parameter is the upper wheel speed. Next wheel speed Constrained by the drive motor, the extrusion amount Due to the constraints imposed by the type of ball, the following boundary constraints apply:

[0051]

[0052] In the formula, and The speed of the previous wheel The minimum and maximum values, and For the next wheel speed The minimum and maximum values, and Extrusion amount The minimum and maximum values;

[0053] Based on the objective function, boundary constraints, and constraint relationships, a sequential least squares quadratic programming approach is used to solve the problem, which yields the desired speed. and desired rotation speed To obtain the optimal upper wheel speed Next wheel speed and extrusion volume .

[0054] Furthermore, the energy function is specifically:

[0055] in, The rotational speed of the previous wheel. The speed of the next wheel. This refers to the extrusion amount. This represents the energy function of the previous round. This represents the energy coefficient of the previous round. This represents the energy function for the next round. Indicates the energy coefficient for the next round. The energy function of the extrusion amount. This represents the energy coefficient of the extrusion quantity. Represents the friction energy function. This represents the friction energy coefficient.

[0056] This disclosure also provides a motion control method for a multi-ball diameter, multi-ball pressure adaptive dual-wheel serving robot, mainly including the following steps:

[0057] Based on the set serve parameters, including: squeeze amount and desired pitch angle Solve for the motion displacement of the lifting module The rotation angle of the pitch swing arm (302) of the ball extrusion module The specific calculation process includes:

[0058] (1) Calculate the angle between the line connecting the centers of the upper and lower serving wheels and the direction of motion of the lifting module:

[0059] ,

[0060] In the formula, The length of the pitch control arm (302); The desired pitch angle for the serve is also the angle between the line connecting the centers of the upper and lower serve wheels and the vertical direction; The angle between the direction of motion of the lifting module and the vertical direction is defined as the median value of the range of motion of the pitch swing arm (302); The distance between the centers of the upper and lower service wheels. , The diameter of the sphere, The diameter of the serve wheel, This refers to the extrusion amount;

[0061] (2) Calculate the angle between the line connecting the centers of the upper and lower serve wheels and the pitching arm (302).

[0062] ;

[0063] (3) The motion displacement of the lifting module to be determined is calculated. Furthermore, the control quantity of the lead screw stepper motor (213) is obtained based on the lead screw lead;

[0064] (4) Finally, the rotation angle of the pitch swing arm (302) is obtained. ;

[0065] By extrusion amount and desired pitch angle Calculate the motion displacement of the lifting module and the rotation angle of the pitch swing arm (302) Then, based on the reduction ratio, the control quantity of the pitch stepper motor (207) is obtained.

[0066] This invention solves the core pain points of ball-serving robots on the market that lack automatic spacing adjustment and self-locking by using an adaptive ball delivery channel module and a trapezoidal screw self-locking automatic spacing adjustment structure. It can simultaneously launch various balls such as tennis balls, peak balls, and baseballs with different diameters and ball pressures.

[0067] Compared with the prior art, the beneficial effects of this disclosure are:

[0068] ① Compatible with all types of balls: It can adaptively adapt to tennis balls, peak balls, baseballs and other balls with different pressures, such as 65±2mm and 70±2mm balls, breaking the limitation of a single ball type, greatly expanding the training scenarios and realizing multiple uses of one machine.

[0069] ② Stable and reliable serve: The trapezoidal screw has an inherent self-locking function, and the lifting mechanism remains stationary when the ball is squeezed for a serve, without displacement or drift; at the same time, the channel design based on the Archimedes spiral achieves precise tangency at any pitch angle, resulting in extremely high consistency of the serve trajectory.

[0070] ③ Micrometer-level non-destructive adjustment: Trapezoidal lead screw servo control achieves micrometer-level compensation for wheel pitch and height, combined with flexible channel guidance, to avoid excessive compression of the ball and protect the structural integrity of the ball.

[0071] ④ Intelligent, collaborative and efficient: The modules are linked and adapted through kinematic models, without the need for manual intervention, and automatically complete the ball type identification, parameter calculation and posture adjustment, adapting to the automated operation of the intelligent ball serving robot.

[0072] ⑤ High reliability and long lifespan: The core transmission and guiding components are made of wear-resistant materials and have a long-lasting lubrication design. The structure is simple and reliable, with no complex pneumatic or hydraulic components, resulting in a low failure rate, significantly improved service life, and reduced maintenance costs.

[0073] ⑥ A squeeze-based ball control method for a dual-wheel serving robot based on ball attributes was established: using an optimization algorithm, solutions were obtained for two constraints (serving speed and spin speed) and three unknowns (upper wheel speed, lower wheel speed, and squeeze amount). By adjusting the weight coefficients of the objective function, the serving robot can achieve the most suitable performance in different application scenarios. For example, for scenarios powered by personal batteries, the compression amount can be appropriately increased to increase the battery life; for scenarios used in club training halls with power outlets, the compression amount can be appropriately reduced to reduce the impact on the equipment and damage to the ball, thereby increasing the service life of the equipment and the ball.

[0074] ⑦ A motion control method for the lifting module, left and right pitch joint module and ball squeezing module of the serving robot described in this disclosure is established: by utilizing structural principles, the displacement control amount of the lifting mechanism and the rotation angle of the pitch arm are obtained through the squeezing amount and the desired serving pitch angle, thereby achieving precise quantitative serving control. Attached Figure Description

[0075] The above and other objects, features and advantages of this disclosure will become more apparent from the more detailed description of exemplary embodiments of this disclosure taken in conjunction with the accompanying drawings, in which the same reference numerals generally represent the same components.

[0076] Figure 1 This is a schematic diagram of the overall structure assembly according to an exemplary embodiment of the present disclosure; the diagram includes: a lifting module 001, a left and right tilt joint module 002, a ball extrusion module 003, a channel module 004, a base module 005, and a ball supply module 006;

[0077] Figure 2 is a structural schematic diagram of the lifting module 001; the diagram includes: linear bearing 101, lead screw nut 102, lifting bracket 103, upper wheel brushless motor 104, and serving upper wheel 105;

[0078] Figure 3 is a structural schematic diagram of the left and right pitch joint module 002; in the figure: lead screw motor bearing 201, lead screw motor bearing seat 202, optical axis guide rail 203, lead screw motor upper limit sensor 204, lead screw motor lower limit sensor 205, lead screw motor mounting seat 206, pitch stepper motor 207, pitch zero point position sensor 208, left and right rotation zero point position sensor 209, left and right rotation drive gear 210, left and right rotation bearing seat 211, left and right rotation bearing seat flange cover 212, lead screw stepper motor 213, left and right pitch bracket 214, pitch rotation bearing flange cover A215, pitch rotation drive gear 216, left and right stepper motor 217, diffuse reflection sensor 218;

[0079] Figure 4 is a structural schematic diagram of the ball extrusion module 003; in the figure: pitch bearing 301, pitch swing arm 302, pitch rotation bearing flange cover B303, ball delivery channel bearing 304, lower wheel brushless motor 305, and lower ball delivery wheel 306.

[0080] Figure 5 is a structural schematic diagram of channel module 004; in the figure: U-shaped bearing 401, ball feeding channel 402;

[0081] Figure 6 is a structural schematic diagram of the base module 005; in the figure: base 501, base circuit board 502, base left and right rotating support wheel 503, left and right rotating driven gear 504, left and right rotating bearing 505, base rubber foot pad 506.

[0082] Figure 7 Simplified schematic diagrams of the lifting module, left and right pitch joint module, and ball extrusion module are provided for solving the control objectives of the motion control unit. Detailed Implementation

[0083] Preferred embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While preferred embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art.

[0084] This disclosure provides a ball-serving robot that can automatically adapt to multiple ball diameters and pressures, possesses reliable self-locking functionality, and achieves precise guidance from all angles. It can adaptively adapt to various sizes of tennis balls, pickles, baseballs, and balls with different pressures, including 65±2mm and 70±2mm. Its core components are an adaptive ball delivery channel module and a high-precision lifting and adjusting module based on trapezoidal screw self-locking control, making it suitable for intelligent training scenarios involving multiple ball types.

[0085] The robot mainly includes: a lifting module 001, a left and right pitch joint module 002, a ball extrusion module 003, a channel module 004, a base module 005, a ball supply module 006, and a control unit. Among them:

[0086] The base module 005 serves as the basic support carrier for the entire machine, and the remaining modules are sequentially assembled on the base module; the ball supply module 006 is located at the feeding end of the channel module 004; the left and right tilt joint modules 002 are respectively connected to the lifting module 001, the ball extrusion module 003, and the channel module 004; the ball extrusion module 003 and the lifting module 001 cooperate to form a double-wheel ball launching structure based on the upper and lower wheels.

[0087] The control unit controls the movement of each motion module based on the current ball diameter, ball pressure, and desired serving attributes such as serving speed and spin speed. This includes adjusting the posture and angle of the ball delivery channel, the lifting and lowering displacement of the serving wheel, and the rotation speed of the upper and lower serving wheels, thus completing the serve.

[0088] As a preferred embodiment, the channel module 004 includes: a ball delivery channel (402) and a U-shaped bearing (401); the ball delivery channel (402) is a curved tube structure, with a gradient step and flexible guide surface at the bottom and side wall of the channel, which can be adapted to tennis balls, pickles, baseballs and balls of different pressures with a diameter of 65±2mm and 70±2mm; the bottom of the inlet end of the ball delivery channel (402) is embedded in the Archimedes spiral groove on the left and right pitch brackets (214) through the U-shaped bearing (401); the outlet end of the ball delivery channel (402) is hinged to the pitch swing arm (302) through the ball delivery channel bearing (304) of the ball extrusion module; within the pitch angle range of -10° to 50°, the ball output by the ball delivery channel (402) always maintains dynamic and precise tangency with the serving wheel (105).

[0089] The channel module 004 and the Archimedes spiral groove are calculated using inverse kinematics and tangent constraint equations to ensure that the ball output from the channel is precisely tangent to the serving wheel at the full pitch angle, thus avoiding ball jamming and deviation of the ball trajectory.

[0090] Preferably, the lifting module 001 includes: a linear bearing (101), a trapezoidal screw nut (102), a lifting bracket (103), an upper wheel brushless motor (104), and a serving upper wheel (105). The lifting bracket (103) rigidly supports the upper wheel brushless motor (104) and the serving upper wheel (105), and can adjust the height of the serving upper wheel according to changes in ball diameter and ball pressure to dynamically compensate for the distance between the two wheels and the serving height. The linear bearing (101) is symmetrically arranged on the frame, providing a backlash-free linear guide for the lifting bracket (103). The trapezoidal screw nut (102) cooperates with a C3-grade trapezoidal screw, along with a servo motor and encoder, to achieve micron-level distance / height adjustment. Simultaneously, utilizing the mechanical self-locking characteristic of the trapezoidal screw (the screw's thread helix angle is less than the equivalent friction angle, possessing inherent mechanical self-locking properties; even after adjustment, the motor remains rigidly self-locked even when power is off), locking is achieved after adjustment, ensuring the lifting mechanism remains stationary during ball compression.

[0091] As a preferred embodiment, the ball supply module (006) located at the feeding end of the channel module (004) is equipped with a built-in sensing unit for real-time acquisition of ball diameter and ball pressure related parameters.

[0092] The following is a further detailed description of an exemplary embodiment of a multi-ball diameter, multi-ball pressure adaptive dual-wheel serving robot.

[0093] The structure is as shown in the attached figure. Figures 1-6 As shown. Figure 1 The diagram shows the assembly relationships and overall layout between the modules; Figure 2 The image shows the T-shaped lead screw drive, linear guide, and height adjustment structure of the serve roller in the lifting module; Figure 3 The drive and sensing structures for left and right rotation, pitch adjustment, and lead screw pitch adjustment in the left and right pitch joint module are shown. Figure 4 The dual-wheel extrusion ball serving and the ball extrusion module swing arm hinge support structure were demonstrated; Figure 5 The arc-shaped motion guide structure of the ball delivery channel and the main body of the multi-ball diameter adaptable channel are demonstrated; Figure 6 The base module's overall support, slewing support, and electrical installation foundation structure are displayed.

[0094] I. Structure

[0095] It mainly includes six modules: lifting module 001, left and right tilt joint module 002, ball squeezing module 003, channel module 004, base module 005, and ball supply module 006. These modules cooperate and work together to form a complete adaptive ball serving system.

[0096] ① The base module 005 serves as the basic support structure for the entire machine, providing an installation carrier and electrical installation space for all other modules. It also enables the stable placement and left-right rotation support of the entire machine, ensuring smooth operation.

[0097] ②The ball supply module 006 is installed at the upper feeding end of the whole machine and is responsible for receiving and launching the ball.

[0098] In this embodiment, the ball supplied by the ball module falls into the ball delivery channel of the channel module by gravity.

[0099] In addition, in this embodiment, the ball supply module collects relevant parameters such as ball diameter and ball pressure in real time through the built-in sensing unit, and transmits the signals to the control system to complete the automatic identification of ball type and parameter calibration, providing data support for subsequent adjustment.

[0100] ③ After receiving the signal from the ball supply module 006, the control system issues commands to the left and right tilt joint module 002 and the lifting module 001;

[0101] Among them, the left and right pitch joint module 002 serves as the core of motion drive, driving the ball extrusion module 003 and the channel module 004 to complete the adjustment of pitch angle and left and right steering, while providing power support for the screw drive of the lifting module 001.

[0102] After receiving the command, the lifting module 001 uses a trapezoidal screw drive to precisely adjust the height of the ball-serving upper wheel and the distance between the two wheels. Once adjusted, it relies on the inherent mechanical properties of the trapezoidal screw to achieve self-locking, ensuring that the mechanism has no displacement when squeezing the ball to serve.

[0103] The lower ball-serving roller in the ball-squeezing module 003 works in conjunction with the upper ball-serving roller in the lifting module 001 to form a double-roller extrusion ball-serving structure, which receives the ball conveyed by the channel module 004.

[0104] ④ The main components of channel module 004 are the ball feeding channel and the U-shaped bearing.

[0105] The bottom of the ball delivery channel inlet is embedded in the arc-shaped groove of the left and right pitch bracket of the left and right pitch joint module 002 via the U-shaped bearing. The outlet end is hinged to the pitch swing arm 302 of the ball extrusion module 003. The upper part of the outlet end is the upper serving wheel, and the lower part is the lower serving wheel.

[0106] The left and right pitch joint module (002) drives the ball extrusion module (003) and the channel module (004) to adjust the pitch angle and left and right rotation. At this time, the outlet end of the ball delivery channel rotates at the center of the pitch swing arm 302 of the ball extrusion module, while the inlet end slides in the arc-shaped groove through the U-shaped bearing, forming an arc-shaped sliding fit with the arc-shaped groove; so that the ball delivery channel automatically adjusts its posture with the change of pitch angle, ensuring that the ball at the channel outlet is always tangent to the ball serving wheel, and smoothly guides the ball delivered by the ball supply module 006 to the double wheel extrusion area.

[0107] The ball delivery channel adopts an arc-shaped curved tube design with steps on the side wall. Balls with a diameter smaller than the width of the channel bottom roll along the bottom of the channel; balls with a diameter larger than the width of the channel bottom roll along the steps on the side wall, thus adapting to balls of different diameters. At the same time, the lifting module controls the up-and-down movement of the serving wheel in the vertical direction, ensuring that balls of different diameters can roll within the arc of the curved tube, and at the exit end, they are tangent to the serving wheel to obtain initial velocity.

[0108] The channel module moves in conjunction with the left and right pitch joint module and the ball extrusion module. The ball extrusion module (003) and the channel module (004) adjust the pitch angle and left and right direction by being driven by the left and right pitch joint module (002). The outlet end of the ball delivery channel rotates with the center of the pitch swing arm of the ball extrusion module, while the inlet end slides in the groove through a U-shaped bearing.

[0109] The arc-shaped slide is a metal slide on the sheet metal of the left and right pitch joint module that fixes the left and right pitch motors. Preferably, an Archimedes spiral slide is used.

[0110] ⑤ After all modules are adjusted, the ball is launched precisely by differentially squeezing the ball through the high-speed rotation of the upper and lower balls. The entire process achieves self-adaptation for multiple ball diameters and pressures without the need for manual intervention.

[0111] 1. Adaptive ball delivery channel module 004

[0112] (1) Structural composition

[0113] Adaptive guide channel: The curved ball feeding channel 402 is made of high-strength engineering plastic or aerospace aluminum alloy in one piece, and the inner wall is mirror polished to minimize the rolling friction of the ball. The inside of the channel adopts a gradient step and flexible guide surface design, which can naturally adapt to balls of different diameters such as 65±2mm and 70±2mm, while also being compatible with the elastic deformation of balls with different pressures, avoiding ball jamming or excessive compression.

[0114] Hinged linkage unit: High-precision ball feeding channel bearing 304, which hinges the channel outlet end to the pitch swing arm 302, realizes synchronous rotation with the pitch angle, and ensures dynamic coupling between the channel attitude and pitch motion.

[0115] Arc trajectory compensation unit: U-shaped deep groove ball bearing 401, which is embedded in the channel entrance end and has a pre-set Archimedean spiral groove on the left and right pitch bracket 214 embedded in the bottom, forming a rolling fit with the latter to achieve low friction and high precision arc motion compensation.

[0116] (2) Core working principle: Spatial attitude adaptive coupling and multi-sphere diameter compatibility mechanism

[0117] In this embodiment, the channel module, based on kinematic trajectory planning and multi-sphere diameter flexible adaptation principles, achieves non-destructive guidance of spheres of various sizes and angles.

[0118] Multi-diameter flexible adaptation: The gradient steps and flexible guide surface inside the channel, through the redundant design of the geometric contour, can automatically accommodate balls of different diameters such as 65±2mm and 70±2mm, and adapt to the elastic deformation of balls with different pressures. After the ball enters the channel, it is automatically centered and guided, achieving "one channel adapts to all categories" without manual adjustment. It can launch multiple types of balls such as tennis balls, pickles, and baseballs at the same time.

[0119] Archimedean spiral trajectory compensation: When the pitch joint module drive mechanism pitches within the range of -10° to 50°, one end of the channel rotates in a circle with the pitch swing arm 302, while the other end, relying on the U-shaped bearing 401, performs a pure rolling arc motion along the Archimedean spiral groove. This spiral trajectory is precisely calculated through inverse kinematics and tangent constraint equations, ensuring that at any pitch angle, the ball at the channel exit end always maintains dynamic and precise tangency with the outer circumference of the serving wheel 105. Before contacting the lower wheel, the ball only rolls along the tangential direction, obtaining a stable initial velocity.

[0120] Non-damaging guiding mechanism: The ball rolls tangentially throughout the entire process within the channel, subjected only to gravity and rolling friction, without any additional compressive stress. This completely avoids the damage to the ball skin and inner liner caused by traditional compression channels, while ensuring a high degree of consistency between the initial velocity and angle of the ball.

[0121] (3) Technical effects

[0122] Ultra-wide ball compatibility: Single channel is compatible with 65±2mm and 70±2mm tennis balls, peak balls, baseballs and balls of different pressures, and can adapt to a variety of balls at the same time, covering more than 98% of mainstream training ball specifications, filling the gap in multi-category compatibility in the industry.

[0123] Precise tangency at all angles: Based on the trajectory compensation of the Archimedes spiral, the tangency deviation is extremely small within the pitch angle of -10° to 50°, completely eliminating the problems of ball jamming and trajectory deviation.

[0124] Damage-free ball delivery: Tangential rolling mode + flexible guide surface, eliminating the risk of ball compression and deformation, significantly extending the service life of the ball.

[0125] High reliability linkage: The U-shaped bearing rolling friction design results in low motion resistance and low wear, making it suitable for high-speed continuous serve scenarios.

[0126] 2. High-precision trapezoidal lead screw self-locking lifting adjustment module 001

[0127] (1) Structural composition

[0128] High-precision linear guide unit: 4 sets of symmetrically distributed linear bearings 101 provide backlash-free, high-rigidity guidance for lifting motion, completely eliminating lateral sway and torsion, and ensuring precise movement of the lifting mechanism.

[0129] Lead screw self-locking transmission unit: C3 grade precision trapezoidal lead screw nut pair 102, in conjunction with servo type lead screw motor and high precision encoder, realizes micron-level conversion from rotary motion to linear motion. The core adopts trapezoidal lead screw (non-ball screw), and utilizes the inherent mechanical characteristics of trapezoidal lead screw thread helix angle being smaller than equivalent friction angle to achieve reliable self-locking, providing core power for wheel track and height adjustment, while ensuring that the lifting mechanism remains stationary during ball compression and serving.

[0130] Lightweight load-bearing unit: Hollow-out lifting bracket 103, made of carbon fiber composite material or high-strength aluminum alloy, maximizes weight reduction while ensuring rigidity, and supports the upper roller brushless motor 104 and the serve roller 105.

[0131] Precision control unit: The upper brushless motor 104 (using FOC vector control), along with the position feedback encoder and upper and lower limit sensors, constitute a complete closed-loop control system to control the up and down movement of the upper ball wheel 105.

[0132] (2) Core working principle: micron-level pitch adaptive adjustment and self-locking mechanism

[0133] In this embodiment, the lifting module is based on the principle of trapezoidal lead screw self-locking transmission, closed-loop control and attitude coupling adjustment to achieve precise response to changes in ball diameter and ball pressure, while ensuring that the lifting mechanism remains stable during the serve.

[0134] Micron-level lead screw drive and self-locking: The lead screw motor receives commands from the control unit and converts the rotational motion into linear displacement through the C3-level trapezoidal lead screw nut 102. With the feedback of the high-resolution encoder, it achieves single-pulse micron-level adjustment accuracy. It can adjust the relative height of the ball-serving roller according to the changes in ball diameter and ball pressure, accurately compensate for the distance between the two rollers and the serving height, and avoid excessive compression or insufficient clamping of the ball.

[0135] The key is that the trapezoidal lead screw has an inherent mechanical self-locking function. Once adjusted, even if the motor loses power, it can still achieve rigid self-locking by relying on the friction constraint of the thread pair itself. When the ball is squeezed for a serve, the lifting mechanism will not be displaced under the reaction force of the ball, thus ensuring the stability of the serve from a structural perspective.

[0136] Posture coupling linkage: The lifting module, channel module, and pitch joint module form a kinematic linkage. The control unit calculates the optimal height of the serving wheel 105 in real time based on the ball diameter, ball pressure, and pitch angle, and drives the lifting module to dynamically fine-tune to ensure that the ball at the channel exit and the serving wheel always remain tangent, while ensuring that the squeezing force of the two wheels on the ball is within a safe threshold.

[0137] Safety closed-loop protection: The lead screw motor is equipped with upper and lower limit sensors and position feedback encoders to achieve dual protection of hardware limit and software closed loop. Once position deviation or overtravel is detected, the protection mechanism is immediately triggered to ensure adjustment accuracy and equipment safety.

[0138] (3) Technical effects

[0139] Ultra-precision adjustment: The trapezoidal lead screw drive enables micron-level pitch / height adjustment, which can precisely adapt to the minute differences in ball diameter and ball pressure, avoiding damage to the ball.

[0140] Reliable self-locking function: The trapezoidal lead screw has inherent mechanical self-locking, and the lifting mechanism remains stationary when the ball is squeezed for serving, which completely solves the problem of displacement drift during serving in existing equipment and greatly improves the consistency of serving.

[0141] High rigidity and stability: Symmetrical linear bearing guidance + lightweight load-bearing bracket, no swaying or deformation during the lifting process, ensuring the relative positional accuracy of the serving wheel and the channel.

[0142] High-speed response adaptation: FOC brushless motor + closed-loop servo control can quickly respond to ball type switching and angle changes, adapting to the needs of high-speed continuous ball serving.

[0143] Long life and high reliability: The trapezoidal lead screw pair adopts a long-term lubrication design, and both the linear bearing and the U-shaped bearing are made of wear-resistant materials, which significantly improves the service life of the core components.

[0144] II. Control Methods

[0145] 1. A dual-wheel squeeze serve control model based on serve attributes

[0146] Serving attributes include: the expected speed of the robot's serve. and desired rotation speed ,in Indicates top rotation. Indicates irrotation. Indicating backspin, the control parameters for the squeeze serve include: topspin speed. Next wheel speed and extrusion volume This model describes how to achieve the desired speed. and desired rotation speed To obtain the optimal upper wheel speed Next wheel speed and extrusion volume The specific solution steps are as follows:

[0147] (1) Constructing the extrusion volume With the maximum speed of the serve constraint relationship ,in and A coefficient related to the type of ball (inflatable ball, filled ball, and rigid plastic ball, etc.) and the diameter of the ball. For parameters related to the contact surface material and friction coefficient, the above constraint relationship shows that, with a constant extrusion amount, regardless of how the speeds of the upper and lower rollers are adjusted... and It will not increase the serve speed, through the desired speed This allows us to obtain a minimum value of the extrusion amount. ;

[0148] (2) Constructing the extrusion volume With the maximum spin speed of the serve constraint relationship ,in and A coefficient related to the type of ball (inflatable ball, filled ball, and rigid plastic ball, etc.) and the diameter of the ball. For parameters related to the contact surface material and friction coefficient, the above constraint relationship shows that, with a constant extrusion amount, regardless of how the speeds of the upper and lower rollers are adjusted... and It will not increase the serve spin speed, through the desired spin speed This allows us to obtain a minimum value of the extrusion amount. ;

[0149] (3) Take and minimum value and judge The maximum amount of pressure that the serving robot can support for this type of ball. Size, Depending on the type of ball, inflatable balls (such as tennis balls) can withstand a greater maximum amount of compression than filled balls (such as baseballs) and rigid plastic balls (such as peaks). This indicates the desired speed. Expected rotational speed of chord If it cannot be achieved, then it indicates the desired speed. Expected rotational speed of chord This can be achieved; proceed to the next step of optimization.

[0150] (4) Establish the constraint relationship between the serve speed and the rotation speed of the upper and lower rollers.

[0151] In the formula upper wheel speed Next wheel speed , For velocity transmission coefficient, These are parameters related to the friction coefficient. Given the diameter of the serving wheel, the constraint relationship indicates that under a constant extrusion amount, Once the ball reaches a certain size, the serve speed will no longer increase;

[0152] Simultaneously, establish a constraint relationship between the serve spin speed and the rotation speed of the upper and lower wheels.

[0153] In the formula upper wheel speed Next wheel speed , For velocity transmission coefficient, For parameters related to the coefficient of friction, the constraint relationship indicates that under a constant extrusion amount, Once the spin reaches a certain level, the serve spin speed will no longer increase;

[0154] Construct the optimal objective function In the formula , and Weighting coefficients The energy function is, specifically: ,in This represents the energy function of the previous round. This represents the energy coefficient of the previous round. This represents the energy function for the next round. Indicates the energy coefficient for the next round. The energy function of the extrusion amount. This represents the energy coefficient of the extrusion quantity. Represents the friction energy function. Indicates the friction energy coefficient;

[0155] The control parameters of the ball extrusion module to be determined are the upper wheel speed. Next wheel speed Constrained by the drive motor, the extrusion amount Due to the constraints imposed by the type of ball, the following boundary constraints apply. , and The speed of the previous wheel The minimum and maximum values, and For the next wheel speed The minimum and maximum values, and Extrusion amount The minimum and maximum values;

[0156] Based on the above objective function, boundary constraints, and constraint relationships, sequential least squares quadratic programming (SLSQP) is used to solve the problem, which yields the desired speed. and desired rotation speed To obtain the optimal upper wheel speed Next wheel speed and extrusion volume The speed of the upper wheel This refers to the target control quantity of the brushless motor 104 in the upper wheel, and the speed of the lower wheel. This is the target control quantity for the next brushless motor 305.

[0157] 2. Motion control of the lifting module, left and right pitch joint module and extrusion ball module

[0158] The motion control of the lifting module, left and right tilt joint module, and extrusion module mainly addresses the following: given extrusion volume and desired pitch angle Solve for the motion displacement of the lifting module The rotation angle of the pitch control arm 302 of the left and right pitch joint module The specific calculation process is shown in the attached figure. Figure 7 As shown.

[0159] (1) Calculate the angle between the line connecting the centers of the upper and lower serving wheels and the direction of motion of the lifting module.

[0160] ,

[0161] In the formula The length of the pitch control arm 302 The desired pitch angle for the serve is also the angle between the line connecting the centers of the upper and lower serve wheels and the vertical direction. The angle between the direction of motion of the lifting module and the vertical direction is usually defined as the median value of the range of motion of the pitch control arm 302. The distance between the centers of the upper and lower service wheels. , The diameter of the sphere, The diameter of the serve wheel, This refers to the extrusion amount;

[0162] (2) Calculate the angle between the line connecting the centers of the upper and lower serve wheels and the pitching arm 302. ;

[0163] (3) The motion displacement of the lifting module to be determined is calculated. Furthermore, the control quantity of the lead screw stepper motor 213 is obtained based on the lead screw lead;

[0164] (4) Finally, the rotation angle of the pitch swing arm 302 of the left and right pitch joint module is obtained. .

[0165] By extrusion amount and desired pitch angle Solve for the motion displacement of the lifting module The rotation angle of the pitch control arm 302 of the left and right pitch joint module Then, the control quantity of the pitch stepper motor 207 is obtained based on the reduction ratio.

[0166] Application Examples

[0167] (a) Adaptive ball delivery channel module

[0168] Processed ball feeding channel 402: Made of 7075 aviation aluminum alloy or high-strength POM engineering plastic in one piece, with mirror polished inner wall and internally processed with gradient steps and flexible guide surface, adaptable to 65±2mm and 70±2mm balls and different ball pressure deformation, ensuring that tennis balls, peaks, baseballs and other types of balls can pass through smoothly.

[0169] Assemble the hinge unit: Press the high-precision ball feed channel bearing 304 onto one end of the channel and rigidly connect it to the pitch arm 302 with bolts to ensure that there is no gap or looseness at the hinge and realize that the channel rotates synchronously with the pitch arm.

[0170] Install the trajectory compensation unit: Install a U-shaped bearing 401 at the other end of the channel, embed it into the Archimedes spiral groove of the left and right pitch bracket 214, adjust the bearing preload to ensure smooth rolling without jamming, and ensure accurate channel attitude compensation.

[0171] Debugging and verification: Drive the pitch joint module to reciprocate within the range of -10° to 50°, detect the tangency between the channel exit and the serving wheel, and test the passability of different ball types and ball pressures to ensure no ball jamming, no squeezing damage, and stable serving posture.

[0172] (ii) High-precision trapezoidal lead screw self-locking lifting adjustment module

[0173] Assemble the linear guide unit: symmetrically fix 4 sets of linear bearings 101 to the frame to ensure that the parallelism and straightness of the bearing axis meet the accuracy requirements and eliminate lateral wobble and torsion during lifting and lowering.

[0174] Install the lead screw drive unit: Assemble the C3 grade trapezoidal lead screw nut pair 102 (using a trapezoidal lead screw, not a ball screw) at the center of the frame. The lead screw motor and the lead screw are connected through a flexible coupling to ensure coaxiality and accurate transmission. At the same time, verify the self-locking performance of the trapezoidal lead screw to ensure no displacement after adjustment.

[0175] Fixed bearing unit: The lifting bracket 103 is rigidly connected to the lead screw nut 102 and the linear bearing 101. The upper brushless motor 104 and the serving upper wheel 105 are assembled. The coaxiality and parallelism are adjusted to ensure that the serving wheel rotates smoothly.

[0176] Debugging accuracy: The control unit drives the lifting module to complete the full stroke adjustment, and the adjustment accuracy is detected by the laser displacement sensor to verify the closed-loop control and limit protection functions; at the same time, the squeeze ball-launching test is carried out to confirm that the trapezoidal screw self-locking is reliable and that the lifting mechanism has no displacement.

[0177] (III) Assembly and Coordinated Debugging of the Complete Machine

[0178] The lifting module 001 and the left and right tilt joint module 002 are fixed to the base module 005 in sequence to ensure the coaxiality and parallelism of each module and to complete the connection between the transmission components and the electrical components.

[0179] The ball extrusion module 003 is hinged to the left and right pitch joint module 002. One end of the channel module 004 is connected to the ball extrusion module 003, and the other end is embedded in the slide groove of the left and right pitch joint module 002 to complete the mechanical linkage assembly.

[0180] Install ball supply module 006 at the feeding end of channel module 004, connect it to the whole machine control system, power on and debug the linkage effect of each module, verify the coordinated operation of ball type recognition, spacing adjustment, channel attitude compensation and self-locking function, and ensure that multi-diameter and multi-ball pressure balls can be launched stably.

[0181] The above technical solutions are merely exemplary embodiments of the present invention. For those skilled in the art, based on the application methods and principles disclosed in the present invention, it is easy to make various types of improvements or modifications, and not limited to the methods described in the specific embodiments of the present invention. Therefore, the methods described above are merely preferred and not restrictive.

Claims

1. A multi-diameter multi-ball pressure self-adaptive double-wheel serving robot, characterized in that, include: The system includes a base module (005), a ball supply module (006), a channel module (004), a left and right tilt joint module (002), a ball extrusion module (003), a lifting module (001), and a control unit, wherein: The base module (005) serves as the basic support structure for the entire machine. The ball supply module (006) is located at the feed end of the channel module (004); The channel module (004) includes: a ball delivery channel (402) for guiding the ball delivered by the ball supply module (006) to the double-wheel extrusion ball serving area; wherein, the bottom of the inlet end of the ball delivery channel is embedded in the arc-shaped groove on the left and right pitch support of the left and right pitch joint module (002), forming an arc-shaped sliding fit with the groove; the outlet end of the ball delivery channel is hinged to the pitch swing arm of the extrusion module (003); The lifting module (001) and the ball squeezing module (003) are respectively provided with upper and lower serving wheels, forming a double-wheel squeezing serving structure; the lifting module adjusts the distance between the double wheels and the serving height by adjusting the height of the upper serving wheel; Meanwhile, the ball delivery channel is equipped with a gradient step and a flexible guide surface, and the geometric profile adopts a redundant design to adapt to the elastic deformation caused by different ball diameters and different ball pressures. The left and right pitch joint module (002) is used to drive the ball extrusion module (003) and the channel module (004) to complete the adjustment of pitch angle and left and right steering. The control unit is used to control the movement of the left and right pitch joints, the lifting module and the ball squeezing module according to the current ball diameter, ball pressure and the desired serving parameters to complete the serve.

2. The robot of claim 1, wherein, The channel module (004) includes: a ball feeding channel (402) and a U-shaped bearing (401); wherein: The ball delivery channel (402) is a bent tube structure with gradually changing steps on the side wall of the channel for balls with a diameter larger than the bottom surface of the channel to pass through; the channel adopts a flexible guide surface to adapt to the elastic deformation of the ball under different pressures; the bottom surface of the channel is provided with a ball center guide; The bottom of the ball delivery channel (402) entrance end is fitted into the arc-shaped groove on the left and right pitch support (214) of the left and right pitch joint module (002) via a U-shaped bearing (401), and the curved tube of the channel module and the groove form an arc-shaped sliding fit; The side wall of the ball feeding channel outlet is hinged to the ball feeding channel bearing (304) of the ball extrusion module (003) and the pitch swing arm (302) of the ball extrusion module (003); The upper part of the ball delivery channel outlet is the serving wheel, and the height of the serving wheel is adjustable; the lower part is the serving wheel; within the pitch angle range of -10° to 50°, by controlling the relative height of the serving wheel, balls of various diameters output through the ball delivery channel (402) can be tangent to the wheel surface of the serving wheel (105) to obtain initial velocity.

3. The robot of claim 2, wherein, The arc-shaped groove on the left and right pitch support (214) adopts an Archimedes spiral groove.

4. The robot of claim 1, wherein, The lifting module (001) includes: a linear bearing (101), a trapezoidal lead screw nut (102), a lifting bracket (103), an upper wheel brushless motor (104), and a serving upper wheel (105); wherein: The lifting bracket (103) rigidly supports the brushless motor (104) of the upper wheel and the serving upper wheel (105). According to the changes in ball diameter and ball pressure, it drives the serving upper wheel to move in the vertical direction to dynamically compensate for the distance between the two wheels and the serving height. The linear bearings (101) are symmetrically arranged on the frame to provide gapless linear guidance for the lifting support (103); The trapezoidal lead screw nut (102) cooperates with the trapezoidal lead screw to convert rotational motion into linear displacement. In conjunction with the servo motor and encoder, it enables minute adjustment of the distance between the two wheels. At the same time, the mechanical self-locking characteristic of the trapezoidal lead screw is used to lock the adjustment in place, ensuring that the lifting mechanism remains stationary when the ball is squeezed out.

5. The robot according to any of claims 1-4, characterized in that, The ball supply module (006) is equipped with a built-in sensing unit for real-time acquisition of parameters related to the ball diameter and ball pressure.

6. A method for controlling the squeeze serve of a dual-wheel serving robot based on serving attributes, applied to the serving robot of claim 1, characterized in that, Includes the following steps: Based on the set serving attributes, including the expected speed of the serving robot's serve. and desired rotation speed ,in Indicates top rotation. Indicates irrotation. Indicates backspin; solve for the control parameters of the squeeze serve, including: the rotation speed of the serve's upper roller. Next wheel speed and extrusion volume Specific methods include: S1, constructing the extrusion volume With the maximum speed of the serve Constraints: ， in, and A coefficient related to the type and diameter of the ball. These are parameters related to the contact surface material and the coefficient of friction. Then based on the expected speed To obtain a minimum value of the extrusion amount: ； S2, constructing extrusion volume With the maximum spin speed of the serve Constraints: ， in, and A coefficient related to the type and diameter of the ball. These are parameters related to the contact surface material and the coefficient of friction. Then based on the desired rotation speed To obtain a minimum value of the extrusion amount ； S3, take and minimum value and judge The maximum amount of pressure that the serving robot can support for each type of ball. Size, Determined by the type of ball, if This indicates the desired speed. Expected rotational speed of chord If it cannot be achieved, then it indicates the desired speed. Expected rotational speed of chord This can be achieved; proceed to the next step of optimization. S4, establish the constraint relationship between the serve speed and the rotation speed of the upper and lower rollers. ； In the formula, upper wheel speed Next wheel speed , For velocity transmission coefficient, These are parameters related to the friction coefficient. The diameter of the serve wheel; At the same time, a constraint relationship is established between the serve spin speed and the rotation speed of the upper and lower rollers: ； In the formula, upper wheel speed Next wheel speed , For velocity transmission coefficient, These are parameters related to the coefficient of friction. Construct the optimal objective function: ； In the formula, , and Weighting coefficients It is an energy function; The required extrusion control parameter is the upper wheel speed. Next wheel speed Constrained by the drive motor, the extrusion amount Due to the constraints imposed by the type of ball, the following boundary constraints apply: ； In the formula, and The speed of the previous wheel The minimum and maximum values, and For the next wheel speed The minimum and maximum values, and Extrusion amount The minimum and maximum values; Based on the objective function, boundary constraints, and constraint relationships, a sequential least squares quadratic programming approach is used to solve the problem, which yields the desired speed. and desired rotation speed To obtain the optimal upper wheel speed Next wheel speed and extrusion volume .

7. The squeeze serve control method according to claim 6, characterized in that, The energy function is specifically: ； in, The rotational speed of the previous wheel. The speed of the next wheel, This refers to the extrusion amount. This represents the energy function of the previous round. This represents the energy coefficient of the previous round. This represents the energy function for the next round. Indicates the energy coefficient for the next round. The energy function of the extrusion amount. This indicates the energy coefficient of the extrusion quantity. Represents the friction energy function. This represents the friction energy coefficient.

8. A motion control method for a multi-ball diameter, multi-ball pressure adaptive dual-wheel serving robot applied to the serving robot of claim 1, characterized in that, Includes the following steps: Based on the set serve parameters, including: squeeze amount and desired pitch angle Solve for the motion displacement of the lifting module The rotation angle of the pitch swing arm (302) of the ball extrusion module The specific calculation process includes: (1) Calculate the angle between the line connecting the centers of the upper and lower serving wheels and the direction of motion of the lifting module: ， In the formula, The length of the pitch control arm (302); The desired pitch angle for the serve is also the angle between the line connecting the centers of the upper and lower serve wheels and the vertical direction; The angle between the direction of motion of the lifting module and the vertical direction is defined as the median value of the range of motion of the pitch swing arm (302); The distance between the centers of the upper and lower service wheels. , The diameter of the sphere, The diameter of the serve wheel, This refers to the extrusion amount; (2) Calculate the angle between the line connecting the centers of the upper and lower serve wheels and the pitching arm (302). ； (3) The motion displacement of the lifting module to be determined is calculated. Furthermore, the control quantity of the lead screw stepper motor (213) is obtained based on the lead screw lead; (4) Finally, the rotation angle of the pitch swing arm (302) is obtained. ; By extrusion amount and desired pitch angle Calculate the motion displacement of the lifting module and the rotation angle of the pitch swing arm (302) Then, based on the reduction ratio, the control quantity of the pitch stepper motor (207) is obtained.

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