Tennis pitching machine ball squeezing wheel control system and control method

Abstract

The invention provides a tennis pitching machine ball squeezing wheel control system and method. The control system comprises a main control module, an upper wheel motor module and a lower wheel motor module, wherein the upper wheel motor module and the lower wheel motor module are connected with the main control module; the main control module is used for sending full duty ratio PWM signals to the upper wheel motor module and the lower wheel motor module. The upper wheel motor module and the lower wheel motor module are respectively used for detecting the current and the rotating speed of the ball extruding upper wheel motor and the ball extruding lower wheel motor and sending the current and the rotating speed to the main control module; the master control module outputs PWM signals with the required duty ratio to the upper wheel motor module and the lower wheel motor module in a PID control mode. The main control module is further used for correspondingly judging whether the ball extruding upper wheel motor and the ball extruding lower wheel motor are started or accelerated to the target rotating speed according to the rotating speed of the ball extruding upper wheel motor and the rotating speed of the ball extruding lower wheel motor, and then PWM signals output by the upper wheel motor module and the lower wheel motor module are adjusted. According to the invention, quick starting and quick switching of the ball squeezing wheel motor can be realized, and the user experience is enhanced.

Description

Technical Field

[0001] The invention belongs to the technical field of sports equipment, and in particular relates to a control system and a control method for a ball squeezing wheel of a tennis ball serving machine. Background Art

[0002] As an important device to improve the efficiency of tennis training, tennis serving machines are widely used in professional training and amateur daily practice. In order to simulate real game situations, modern tennis serving machines need to be able to not only launch tennis balls at different speeds, but also have the ability to adjust the rotation of the ball. This requires that the internal drive motor has sufficient torque to achieve high-speed serving (usually over 100km / h), and can quickly adjust the rotation speed in a short period of time to change the speed and rotation type of the ball.

[0003] Most high-performance tennis serving machines on the market currently use brushed DC motors as power sources. This type of motor is known for its high power density and good speed regulation performance. However, since these motors consume very large currents at startup - around 20A at rated voltage - this poses a considerable challenge to the power supply system. Especially considering that most tennis serving machines are deployed in outdoor environments and tend to use rechargeable lithium batteries as power sources, this further limits the battery capacity and discharge capacity that can be used. Generally, due to portability, the selected lithium battery capacity is about 5000mAh, supporting a maximum 3C discharge rate, or a peak current output of 15A. Therefore, how to effectively manage the high current during the startup phase becomes one of the key issues in the design.

[0004] In response to the above challenges, a common strategy currently adopted is to soft-start the motor through PWM (pulse width modulation) technology. The specific approach is to only provide a PWM signal with a small duty cycle (for example, 20%) to the motor at the beginning of the startup, thereby limiting the starting current level; then as the motor gradually accelerates, the duty cycle of the PWM signal is gradually increased until the target operating state is reached. Although this method helps to alleviate the adverse effects of large current shocks, it also brings obvious disadvantages: first, the startup process becomes quite slow, and it may take up to 10 to 20 seconds to accelerate from a standstill to a preset speed; second, when it is necessary to frequently switch between different working modes (for example, quickly increase from a low speed of 20km / h to a high speed of 100km / h or vice versa), it is also limited by this progressive control method, resulting in an overall response speed that is not ideal and difficult to meet the needs of flexible adjustment in practical applications. Summary of the invention

[0005] In order to overcome the problems existing in the related art at least to a certain extent, the present invention provides a control system and a control method for a ball squeezing wheel of a tennis ball serving machine.

[0006] According to a first aspect of an embodiment of the present invention, the present invention provides a tennis ball serving machine ball squeezing wheel control system, which includes a main control module and an upper wheel motor module and a lower wheel motor module connected to the main control module;

[0007] The main control module is used to send a full duty cycle PWM signal to the upper wheel motor module and the lower wheel motor module to control the squeezing ball upper wheel motor in the upper wheel motor module and the squeezing ball lower wheel motor in the lower wheel motor module to start or accelerate;

[0008] The upper wheel motor module is used to detect the current and speed of the upper wheel motor of the ball squeezing device and send them to the main control module, and the lower wheel motor module is used to detect the current and speed of the lower wheel motor of the ball squeezing device and send them to the main control module;

[0009] The main control module is used to output a PWM signal of a required duty cycle to the upper wheel motor module in a PID control manner according to the received current of the upper wheel motor of the ball squeezing, so as to drive the upper wheel motor of the ball squeezing to operate; the main control module is also used to output a PWM signal of a required duty cycle to the lower wheel motor module in a PID control manner according to the received current of the lower wheel motor of the ball squeezing, so as to drive the lower wheel motor of the ball squeezing to operate;

[0010] The main control module is also used to judge whether the upper wheel motor of the squeezing ball has been started or accelerated to the target speed of the upper wheel motor according to the received speed of the upper wheel motor of the squeezing ball, and to judge whether the lower wheel motor of the squeezing ball has been started or accelerated to the target speed of the lower wheel motor according to the received speed of the lower wheel motor of the squeezing ball, and then adjust the PWM signal output to the upper wheel motor module and the lower wheel motor module according to the judgment result.

[0011] According to the tennis ball machine squeezing wheel control system provided by the present invention, the upper wheel motor module includes a first auxiliary control module, a first brake module, a squeezing upper wheel motor, an upper wheel current detection module and an upper wheel speed encoder;

[0012] The first auxiliary control module is connected to the main control module and is used to receive the PWM signal sent by the main control module; the first auxiliary control module is connected to the first braking module and the upper wheel motor of the ball squeezing ball and is used to control the operation of the upper wheel motor of the ball squeezing ball, and is also used to control the deceleration braking of the upper wheel motor of the ball squeezing ball through the first braking module; the upper wheel current detection module is used to detect the operating current of the upper wheel motor of the ball squeezing ball and send it to the main control module, and the upper wheel speed encoder is used to detect the rotational speed of the upper wheel motor of the ball squeezing ball and send it to the main control module.

[0013] Furthermore, the lower wheel motor module includes a second auxiliary control module, a second brake module, a ball squeezing lower wheel motor, a lower wheel current detection module and a lower wheel speed encoder;

[0014] The second auxiliary control module is connected to the main control module and is used to receive the PWM signal sent by the main control module; the second auxiliary control module is connected to the second braking module and the lower wheel motor of the ball squeezing ball and is used to control the operation of the lower wheel motor of the ball squeezing ball, and is also used to control the deceleration braking of the lower wheel motor of the ball squeezing ball through the second braking module; the lower wheel current detection module is used to detect the operating current of the lower wheel motor of the ball squeezing ball and send it to the main control module, and the lower wheel speed encoder is used to detect the rotational speed of the lower wheel motor of the ball squeezing ball and send it to the main control module.

[0015] Furthermore, the first auxiliary control module is implemented by an H half-bridge circuit, the first braking module is implemented by a braking circuit, and the upper wheel current detection module is implemented by a sampling and amplifying circuit.

[0016] Furthermore, the H half-bridge circuit includes a first field effect transistor and a second field effect transistor, the gate of the first field effect transistor is connected to the first IO port of the main control module, the drain of the first field effect transistor is connected to the positive pole of the motor power supply, the negative pole of the motor power supply is grounded, the source of the first field effect transistor is connected to one end of the ball squeezing upper wheel motor and the drain of the second field effect transistor; the gate of the second field effect transistor is connected to the second IO port of the main control module, and the source of the second field effect transistor is connected to the other end of the ball squeezing upper wheel motor.

[0017] Furthermore, the braking circuit includes a third field effect transistor and a braking resistor, the gate of the third field effect transistor is connected to the third IO port of the main control module, the drain is connected to the source of the first field effect transistor through the braking resistor, and the source of the third field effect transistor is grounded.

[0018] Furthermore, the sampling and amplifying circuit includes a sampling resistor and a current amplifier, one end of the sampling resistor is connected to the source of the second field effect transistor, and the other end thereof is grounded; the two input ports of the current amplifier are respectively connected to the two ends of the sampling resistor, and the output port thereof is connected to the fourth IO port of the main control module.

[0019] Furthermore, the main control module is configured with a startup program and an acceleration program, and the process of the startup program and the acceleration program is as follows:

[0020] Output full duty cycle PWM signal to the upper wheel motor module and the lower wheel motor module to control the upper wheel motor and the lower wheel motor of the ball squeezing device to start or accelerate;

[0021] Receive the running current of the upper wheel motor of the ball squeezing device detected by the upper wheel current detection module and the running current of the lower wheel motor of the ball squeezing device detected by the lower wheel current detection module;

[0022] According to the received running current, the running current of the upper wheel motor and the lower wheel motor of the ball squeezing device is controlled by PID control, and a PWM signal with a required duty cycle is output so that the running current is maintained at a preset target current;

[0023] Outputting the PWM signal of the required duty cycle to the upper wheel motor module and the lower wheel motor module, so as to control the operation of the upper wheel motor and the lower wheel motor of the ball squeezing device by using the PWM signal of the required duty cycle;

[0024] The rotation speeds of the upper wheel motor and the lower wheel motor detected by the upper wheel speed encoder and the lower wheel speed encoder are obtained, and when it is determined that the obtained rotation speed reaches the first target rotation speed, the startup or acceleration program is exited.

[0025] Furthermore, the main control module is configured with a deceleration and braking program, and the process of the deceleration and braking program is as follows:

[0026] Turn off the power supply of the motor, control to open the first brake module and the second brake module, and the motor current is braked through the first brake module and the second brake module;

[0027] The rotation speeds of the upper wheel motor and the lower wheel motor detected by the upper wheel speed encoder and the lower wheel speed encoder are obtained, and when it is determined that the obtained rotation speed reaches the second target rotation speed, the deceleration and braking program is exited.

[0028] According to a second aspect of an embodiment of the present invention, the present invention further provides a tennis ball machine squeezing wheel control method based on any of the above tennis ball machine squeezing wheel control systems, characterized in that it includes a starting process, an acceleration process and a deceleration braking process;

[0029] The startup process and acceleration process include the following steps:

[0030] The main control module outputs a full duty cycle PWM signal to the upper wheel motor module and the lower wheel motor module to control the ball squeezing upper wheel motor in the upper wheel motor module and the ball squeezing lower wheel motor in the lower wheel motor module to start or accelerate;

[0031] The upper wheel current detection module detects the running current of the upper wheel motor of the squeezing ball, and the lower wheel current detection module detects the running current of the lower wheel motor of the squeezing ball, and feeds back the detected running current to the main control module;

[0032] The main control module uses PID control to output PWM signals with the required duty cycle to the upper wheel motor module and the lower wheel motor module according to the received running current;

[0033] The first auxiliary control module in the upper wheel motor module and the second auxiliary control module in the lower wheel motor module control the operation of the upper wheel motor and the lower wheel motor of the ball squeezing device according to the received PWM signal of the required duty cycle;

[0034] The upper wheel speed encoder detects the speed of the upper wheel motor of the squeezing ball, and the lower wheel speed encoder detects the speed of the lower wheel motor of the squeezing ball, and feeds the detected speed back to the main control module;

[0035] The main control module compares the acquired rotation speed with a preset first target rotation speed, and exits the startup or acceleration procedure if the acquired rotation speed reaches the first target rotation speed;

[0036] The deceleration braking process comprises the following steps:

[0037] The main control module controls the first brake module and the second brake module to open respectively through the first auxiliary control module and the second auxiliary control module, so as to brake the upper wheel motor and the lower wheel motor of the squeezing ball;

[0038] The upper wheel speed encoder detects the speed of the upper wheel motor of the squeezing ball, and the lower wheel speed encoder detects the speed of the lower wheel motor of the squeezing ball, and feeds the detected speed back to the main control module;

[0039] The main control module compares the acquired rotation speed with a preset second target rotation speed, and exits the deceleration braking procedure if the acquired rotation speed reaches the second target rotation speed.

[0040] 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 ball serving machine ball squeezing wheel control system and control method provided by the present invention can realize precise control of the ball squeezing upper wheel motor and the ball squeezing lower wheel motor by integrating the main control module, the upper wheel motor module and the lower wheel motor module, and adopting the PID control method; the tennis ball serving machine ball squeezing wheel control system and control method provided by the present invention can significantly shorten the time required from static to target speed by directly sending a full duty cycle PWM signal during the startup phase, so as to prompt the ball squeezing upper wheel motor and the ball squeezing lower wheel motor to quickly reach the working state; the PID control method can adjust the output signal according to real-time feedback, and can effectively manage the subsequent acceleration process even after the initial full-power startup, ensuring a quick and smooth transition to the target speed.

[0041] The tennis serving machine ball squeezing wheel control system and control method provided by the present invention can not only solve the problems of slow startup, slow response, slow switching, etc. in the prior art, but also provide users with a more efficient and stable serving solution through precise speed control and optimized energy consumption management.

[0042] It should be understood that the above 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

[0043] 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.

[0044] Figure 1 A structural block diagram of a tennis ball serving machine ball squeezing wheel control system provided in a specific embodiment of the present invention;

[0045] Figure 2 A schematic diagram of a control brake circuit in a tennis ball serving machine ball squeezing wheel control system provided in a specific embodiment of the present invention;

[0046] Figure 3 A flowchart of a startup program and an acceleration program of a main control module in a tennis ball serving machine squeezing wheel control system provided by a specific embodiment of the present invention;

[0047] Figure 4 The present invention provides a flowchart of a deceleration and braking program of a main control module in a tennis ball serving machine ball squeezing wheel control system according to a specific embodiment of the present invention.

[0048] Description of reference numerals:

[0049] 11. Main control module;

[0050] 12. Upper wheel motor module; 121. First auxiliary control module; 122. First brake module; 123. Upper wheel motor for squeezing ball; 124. Upper wheel current detection module; 125. Upper wheel speed encoder;

[0051] 13. Lower wheel motor module; 131. Second auxiliary control module; 132. Second brake module; 133. Ball squeezing lower wheel motor; 134. Lower wheel current detection module; 135. Lower wheel speed encoder;

[0052] MOS1: first field effect transistor; MOS2: second field effect transistor; MOS3: third field effect transistor; PWM_H: first IO port; PWM_L: second IO port; SW1: third IO port; ADC1: fourth IO port; R1: brake resistor; R2: sampling resistor; AMP1: current amplifier. DETAILED DESCRIPTION

[0053] 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.

[0054] 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, elements / components with the same or similar reference numerals used in the drawings and embodiments are used to represent the same or similar parts.

[0055] 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.

[0056] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0057] As used herein, "and / or" includes any or all combinations of the items described.

[0058] As used herein, “plurality” includes “two” and “more than two”; as used herein, “plurality of groups” includes “two groups” and “more than two groups”.

[0059] 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.

[0060] Although the existing technical solutions can solve the problem of excessive starting current of the motor of the tennis ball machine to a certain extent, they also introduce new bottlenecks, especially in application scenarios that require higher operational flexibility and faster response speed. Therefore, it is particularly important to develop a new generation of tennis ball machine ball squeezing wheel control system and control method that can ensure efficient energy conversion and quickly respond to changing needs.

[0061] Combine the following Figure 1-Figure 4 The invention describes a control system and a control method for a ball squeezing wheel of a tennis ball serving machine.

[0062] like Figure 1 As shown, the tennis ball serving machine ball squeezing wheel control system provided by the embodiment of the present invention includes a main control module 11 and an upper wheel motor module 12 and a lower wheel motor module 13 connected to the main control module 11. Among them, the main control module 11 is used to send a full duty cycle PWM signal to the upper wheel motor module 12 and the lower wheel motor module 13 to control the ball squeezing upper wheel motor 123 in the upper wheel motor module 12 and the ball squeezing lower wheel motor 133 in the lower wheel motor module 13 to start or accelerate; the upper wheel motor module 12 is used to detect the current and speed of the ball squeezing upper wheel motor 123 and send them to the main control module 11, and the lower wheel motor module 13 is used to detect the current and speed of the ball squeezing lower wheel motor 133 and send them to the main control module 11.

[0063] The main control module 11 is used to output a PWM signal with a required duty cycle to the upper wheel motor module 12 using a PID control method according to the received current of the upper wheel motor 123 of the ball squeezing ball, so as to drive the upper wheel motor 123 to operate; the main control module 11 is also used to output a PWM signal with a required duty cycle to the lower wheel motor module 13 using a PID control method according to the received current of the lower wheel motor 133 of the ball squeezing ball, so as to drive the lower wheel motor 133 to operate.

[0064] The main control module 11 is also used to determine whether the upper wheel motor 123 of the ball squeezing device has been started or accelerated to the target speed of the upper wheel motor according to the received speed of the upper wheel motor 123 of the ball squeezing device, and to determine whether the lower wheel motor 133 of the ball squeezing device has been started or accelerated to the target speed of the lower wheel motor according to the received speed of the lower wheel motor 133 of the ball squeezing device, and then adjust the PWM signals output to the upper wheel motor module 12 and the lower wheel motor module 13 according to the judgment results.

[0065] Specifically, the main control module 11 may be a single chip microcomputer or a similar controller with analog-to-digital conversion and multiple timer peripherals.

[0066] The tennis serving machine ball squeezing wheel control system provided in the embodiment of the present invention can realize precise control of the ball squeezing upper wheel motor 123 and the ball squeezing lower wheel motor 133 by integrating the main control module 11, the upper wheel motor module 12 and the lower wheel motor module 13, and adopting the PID control method.

[0067] The tennis ball serving machine ball squeezing wheel control system provided by the embodiment of the present invention directly sends a full duty cycle PWM signal during the startup phase, prompting the ball squeezing upper wheel motor 123 and the ball squeezing lower wheel motor 133 to quickly reach the working state, significantly shortening the time required from static to target speed. The PID control method can adjust the output signal according to real-time feedback, and even after the initial full-power startup, it can effectively manage the subsequent acceleration process to ensure a smooth transition to the target speed.

[0068] The tennis ball machine squeezing wheel control system provided by the embodiment of the present invention can realize accurate control of the motor speed by dynamically adjusting the duty cycle of the PWM signal through the PID control method by real-time monitoring the current and speed of the squeezing upper wheel motor 123 and the squeezing lower wheel motor 133. This closed-loop control system can automatically correct the output according to the actual operation of the tennis ball machine squeezing wheel, thereby ensuring the consistency and accuracy of the tennis ball machine's serving speed.

[0069] When it is necessary to switch to different speeds, for example, from 20km / h to 100km / h, the PID control method can quickly respond and adjust the PWM signal, so that the upper wheel motor 123 and the lower wheel motor 133 of the ball squeezing ball can reach a new speed in a short time, thereby improving the response speed and flexibility of the system.

[0070] The tennis serving machine ball squeezing wheel control system provided by the present invention can not only solve the problems of slow startup, slow response, slow switching, etc. in the prior art, but also provide users with a more efficient and stable serving solution through precise speed control and optimized energy consumption management.

[0071] In a specific embodiment, the upper wheel motor module 12 includes a first auxiliary control module 121, a first brake module 122, a squeeze ball upper wheel motor 123, an upper wheel current detection module 124 and an upper wheel speed encoder 125. Among them, the first auxiliary control module 121 is connected to the main control module 11, and is used to receive the PWM signal sent by the main control module 11; the first auxiliary control module 121 is connected to the first brake module 122 and the squeeze ball upper wheel motor 123, and is used to control the operation of the squeeze ball upper wheel motor 123, and is also used to control the deceleration and braking of the squeeze ball upper wheel motor 123 through the first brake module 122. The upper wheel current detection module 124 is used to detect the operating current of the squeeze ball upper wheel motor 123 and send it to the main control module 11, and the upper wheel speed encoder 125 is used to detect the rotation speed of the squeeze ball upper wheel motor 123 and send it to the main control module 11.

[0072] The lower wheel motor module 13 includes a second auxiliary control module 131, a second brake module 132, a lower wheel motor 133, a lower wheel current detection module 134 and a lower wheel speed encoder 135. Among them, the second auxiliary control module 131 is connected to the main control module 11, and is used to receive the PWM signal sent by the main control module 11; the second auxiliary control module 131 is connected to the second brake module 132 and the lower wheel motor 133, and is used to control the operation of the lower wheel motor 133, and is also used to control the deceleration and braking of the lower wheel motor 133 through the second brake module 132. The lower wheel current detection module 134 is used to detect the operating current of the lower wheel motor 133 and send it to the main control module 11, and the lower wheel speed encoder 135 is used to detect the rotation speed of the lower wheel motor 133 and send it to the main control module 11.

[0073] The first auxiliary control module 121 and the second auxiliary control module 131 both receive the PWM signal from the main control module 11, and can achieve fine adjustment of the rotation speed of the upper wheel motor 123 and the lower wheel motor 133. By changing the duty cycle of the PWM signal, the rotation speed and torque output of the upper wheel motor 123 and the lower wheel motor 133 can be effectively adjusted to meet the needs under different working conditions.

[0074] The first brake module 122 and the second brake module 132 can quickly cut off the motor power supply or implement reverse electromagnetic braking when necessary, which can effectively slow down or stop the operation of the upper wheel motor 123 and the lower wheel motor 133 of the ball squeezing ball, thereby improving the safety and responsiveness of the system in emergency situations.

[0075] The upper wheel current detection module 124 continuously detects the working state of the upper wheel motor 123 of the squeezing ball, and the lower wheel current detection module 134 continuously detects the working state of the lower wheel motor 133 of the squeezing ball, and feeds back the data to the main control module 11. This instant information transmission mechanism enables the control system to detect abnormal conditions (such as overload) in time, take corresponding measures to avoid the occurrence of potential faults, and extend the service life of the upper wheel motor 123 and the lower wheel motor 133 of the squeezing ball.

[0076] By using the speed information collected by the upper wheel speed measuring encoder 125 and the lower wheel speed measuring encoder 135 and combining it with the current detection result, the actual operating condition of the motor can be analyzed more accurately, providing a basis for the control optimization of the main control module 11.

[0077] In this embodiment, the entire upper wheel motor module 12 and the lower wheel motor module 13 integrate multiple functions such as control, execution, and sensing, which reduces the number of external connection cables, reduces system complexity, and is also conducive to improving the miniaturization design level of the overall device.

[0078] In a specific embodiment, the first auxiliary control module 121 and the second auxiliary control module 131 can both be implemented by an H half-bridge circuit, the first brake module 122 and the second brake module 132 can both be implemented by a brake circuit, and the upper wheel current detection module 124 and the lower wheel current detection module 134 can both be implemented by a sampling amplifier circuit. The motor power supply, the H half-bridge circuit, the brake circuit and the sampling amplifier circuit can constitute a specific control brake circuit, which is different from the H bridge control circuit in the prior art. It combines the half-bridge control and the motor brake circuit to achieve the control function in the simplest way.

[0079] like Figure 2 As shown, the H half-bridge circuit includes a first field effect transistor MOS1 and a second field effect transistor MOS2, the gate of the first field effect transistor MOS1 is connected to the first IO port PWM_H of the main control module, the drain thereof is connected to the positive electrode of the motor power supply, the negative electrode of the motor power supply is grounded, the source of the first field effect transistor MOS1 is connected to one end of the ball squeezing upper wheel motor 123 and the drain of the second field effect transistor MOS2; the gate of the second field effect transistor MOS2 is connected to the second IO port PWM_L of the main control module, and the source thereof is connected to the other end of the ball squeezing upper wheel motor 123.

[0080] The braking circuit includes a third field effect transistor MOS3 and a braking resistor R1. The gate of the third field effect transistor MOS3 is connected to the third IO port SW1 of the main control module, and its drain is connected to the source of the first field effect transistor MOS1 through the braking resistor R1. The source of the third field effect transistor MOS3 is grounded.

[0081] The sampling and amplifying circuit includes a sampling resistor R2 and a current amplifier AMP1. One end of the sampling resistor R2 is connected to the source of the second field effect transistor MOS2, and the other end thereof is grounded. The two input ports of the current amplifier AMP1 are respectively connected to the two ends of the sampling resistor R2, and its output port is connected to the fourth IO port ADC1 of the main control module.

[0082] The working process of the above-mentioned control brake circuit includes the motor acceleration and operation process and the motor braking process, wherein, during the motor acceleration and operation process, the PWM signal of the required duty cycle output by the main control module 11 controls the first field effect tube MOS1 and the second field effect tube MOS2 to open and close, and its specific working principle is: when the duty cycle is full, the first IO port PWM_H of the main control module is high level, the first field effect tube MOS1 is always open, the second IO port PWM_L of the main control module is low level, the second field effect tube MOS2 is always closed, and the squeezing ball upper wheel motor 123 is directly powered by the power supply to accelerate or run. When the duty cycle is 50%, in the entire PWM control cycle, for example, the frequency of the PWM signal is 10kHz, that is, the cycle is 100us, and half of the cycle time is 50us. During this 50us time, the first IO port PWM_H of the main control module is at a high level, the first field effect transistor MOS1 is in the open state, the second IO port PWM_L of the main control module is at a low level, the second field effect transistor MOS2 is in the off state, and the ball squeezing upper wheel motor 123 absorbs current from the power supply; during another 50us time, the first IO port PWM_H of the main control module is at a low level, the first field effect transistor MOS1 is in the off state, the second IO port PWM_L of the main control module is at a high level, the second field effect transistor MOS2 is in the open state, and the ball squeezing upper wheel motor 123 itself continues current through the second field effect transistor MOS2; during the acceleration and operation process, the third IO port SW1 of the main control module is always at a low level, and the third field effect transistor MOS3 is always in the off state.

[0083] During the motor braking process, the first IO port PWM_H and the second IO port PWM_L of the main control module are both at low levels, the first field effect transistor MOS1 and the second field effect transistor MOS2 are both in the off state, the third IO port SW1 of the main control module is at a high level, and the third field effect transistor MOS3 is in the open state, and the ball-squeezing upper wheel motor 123 absorbs the braking energy of the ball-squeezing upper wheel motor 123 through the braking resistor R1.

[0084] In the above embodiment, the main control module 11 is configured with a start-up program, an acceleration program and a deceleration and braking program. The start-up program and the acceleration program have the same process, and both use a full duty cycle to start the upper wheel motor 123 and the lower wheel motor 133 of the squeezing ball, which can greatly shorten the start-up time and acceleration time.

[0085] The full duty cycle is used to start the upper ball-squeezing wheel motor 123 and the lower ball-squeezing wheel motor 133, that is, the power supply voltage is directly loaded to both ends of the motor. Since the torque requirement of the tennis ball serving machine's ball-squeezing wheel is very large, the starting current of the upper ball-squeezing wheel motor 123 and the lower ball-squeezing wheel motor 133 is very large, reaching about 20A, or even higher. If the full duty cycle is always started, the motor current will soon reach 20A, so the power supply current is also required to reach 20A. Limited by the output capacity of the tennis ball serving machine battery in the prior art (generally 5A-10A continuously) and the low cost requirements of components (the cost of high-current components will increase). The present invention is started by full duty cycle, and then the duty cycle of the PWM signal is adjusted in real time according to the detected motor current and the preset current threshold, so that the starting current of the upper ball-squeezing wheel motor 123 and the lower ball-squeezing wheel motor 133 is controlled to the maximum output capacity of the battery power supply. For example, the preset current threshold is 10A. If the current exceeds 10A, the duty cycle of the PWM signal will decrease and will no longer be the full duty cycle. If the current is less than 10A, the load will continue to be applied to accelerate the motor through the full duty cycle.

[0086] like Figure 3 As shown, the process of the startup program and the acceleration program configured in the main control module 11 is:

[0087] A full duty cycle PWM signal is output to the upper wheel motor module 12 and the lower wheel motor module 13 to control the upper wheel motor 123 and the lower wheel motor 133 of the ball squeezing device to start or accelerate.

[0088] The operating current of the upper wheel motor 123 of the ball squeezing device detected by the upper wheel current detection module 124 and the operating current of the lower wheel motor 133 of the ball squeezing device detected by the lower wheel current detection module 134 are received.

[0089] According to the received operating current, the operating current of the upper wheel motor 123 and the lower wheel motor 133 of the ball squeezing device is controlled by PID control, and a PWM signal with the required duty cycle is output, so that the operating current is maintained at a preset target current. By setting the target current, the required operating current will not exceed the output capacity of the battery and can maximize the performance of the upper wheel motor 123 and the lower wheel motor 133 of the ball squeezing device. In order to achieve the fastest acceleration, the target current for motor acceleration can be set to the maximum output current capacity of the battery power supply. For example, if the maximum output current capacity of the battery power supply is 10A, the target current for motor acceleration is set to 10A.

[0090] The PWM signal of the required duty cycle is output to the upper wheel motor module 12 and the lower wheel motor module 13, so as to use the PWM signal of the required duty cycle to control the operation of the upper wheel motor 123 and the lower wheel motor 133 of the squeezing ball.

[0091] Obtain the rotational speeds of the upper wheel motor 123 and the lower wheel motor 133 of the ball-squeezing ball detected by the upper wheel speed encoder 125 and the lower wheel speed encoder 135, and determine whether the obtained rotational speeds reach the first target rotational speed. If so, exit the startup or acceleration program; otherwise, re-receive the operating current of the upper wheel motor 123 and the lower wheel motor 133 of the ball-squeezing ball, and repeat the above process until the rotational speeds of the upper wheel motor 123 and the lower wheel motor 133 of the ball-squeezing ball reach the first target rotational speed.

[0092] like Figure 4 As shown, the process of the deceleration braking program configured in the main control module 11 is:

[0093] Turn off the motor power supply, control to turn on the third field effect tube MOS3, and the motor current is braked through the braking resistor R1 and the third field effect tube MOS3. Specifically, different braking effects can be achieved by selecting different types of braking resistors R1. The selection of braking resistor R1 depends on the braking current and braking time. The braking current determines the braking time. The shorter the required time, the higher the braking current requirement. The calculation formula of braking resistor R1 is: braking resistor R1 = motor back electromotive force / braking current.

[0094] Obtain the rotational speeds of the upper wheel motor 123 and the lower wheel motor 133 of the ball squeezing ball detected by the upper wheel speed measuring encoder 125 and the lower wheel speed measuring encoder 135, and determine whether the obtained rotational speeds reach the second target rotational speed. If so, exit the deceleration braking program; otherwise, adjust the motor current to brake again through the braking resistor R1 and the third field effect transistor MOS3, and repeat the above process until the rotational speeds of the upper wheel motor 123 and the lower wheel motor 133 of the ball squeezing ball reach the second target rotational speed.

[0095] Based on a tennis ball machine squeezing wheel control system provided by the present invention, the present invention also provides a tennis ball machine squeezing wheel control method, which includes a starting process, an acceleration process and a deceleration braking process, and the starting process and the acceleration process include the following steps:

[0096] S1, the main control module 11 outputs a full duty cycle PWM signal to the upper wheel motor module 12 and the lower wheel motor module 13 to control the ball squeezing upper wheel motor 123 in the upper wheel motor module 12 and the ball squeezing lower wheel motor 133 in the lower wheel motor module 13 to start or accelerate.

[0097] S2, the upper wheel current detection module 124 detects the operating current of the upper wheel motor 123 of the squeezing ball, and the lower wheel current detection module 134 detects the operating current of the lower wheel motor 133 of the squeezing ball, and feeds back the detected operating current to the main control module 11.

[0098] S3, the main control module 11 outputs a PWM signal with a required duty cycle to the upper wheel motor module 12 and the lower wheel motor module 13 in a PID control manner according to the received operating current.

[0099] S4, the first auxiliary control module 121 in the upper wheel motor module 12 and the second auxiliary control module 131 in the lower wheel motor module 13 control the operation of the upper wheel motor 123 and the lower wheel motor 133 of the ball squeezing according to the received PWM signal of the required duty cycle.

[0100] S5, the upper wheel speed encoder 125 detects the rotation speed of the upper wheel motor 123 of the squeezing ball, and the lower wheel speed encoder 135 detects the rotation speed of the lower wheel motor 133 of the squeezing ball, and feeds back the detected rotation speed to the main control module 11.

[0101] S6, the main control module 11 compares the acquired rotational speed with the preset first target rotational speed. If the acquired rotational speed reaches the first target rotational speed, the startup or acceleration program is exited; otherwise, the process returns to step S3 and steps S3-S6 are repeated until the rotational speeds of the upper wheel motor 123 and the lower wheel motor 133 of the ball-squeezing device reach the first target rotational speed.

[0102] The deceleration braking process includes the following steps:

[0103] S7. The main control module 11 controls the first brake module 122 and the second brake module 132 to open respectively through the first auxiliary control module 121 and the second auxiliary control module 131, so as to brake the upper wheel motor 123 and the lower wheel motor 133 of the squeezing ball.

[0104] S8, the upper wheel speed encoder 125 detects the rotation speed of the upper wheel motor 123 of the squeezing ball, and the lower wheel speed encoder 135 detects the rotation speed of the lower wheel motor 133 of the squeezing ball, and feeds back the detected rotation speed to the main control module 11.

[0105] S9, the main control module 11 compares the acquired rotational speed with the preset second target rotational speed. If the acquired rotational speed reaches the second target rotational speed, the deceleration braking program is exited. Otherwise, the process returns to step S7 and steps S7-S9 are repeated until the rotational speeds of the upper wheel motor 123 and the lower wheel motor 133 of the ball-squeezing device reach the second target rotational speed.

[0106] The tennis ball serving machine ball squeezing wheel control system and control method provided by the present invention can speed up the starting time of the tennis ball serving machine ball squeezing wheel, ultimately achieving a starting or acceleration time of 1-2 seconds, and can speed up the speed switching time of the tennis ball serving machine ball squeezing wheel, ultimately achieving a speed switching time of 1-2 seconds.

[0107] 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.

[0108] 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 ball machine squeezing wheel control system, characterized in that: It includes a main control module and an upper wheel motor module and a lower wheel motor module connected to the main control module; The main control module is used to send a full duty cycle PWM signal to the upper wheel motor module and the lower wheel motor module to control the squeezing ball upper wheel motor in the upper wheel motor module and the squeezing ball lower wheel motor in the lower wheel motor module to start or accelerate; The upper wheel motor module is used to detect the current and speed of the upper wheel motor of the ball squeezing device and send them to the main control module, and the lower wheel motor module is used to detect the current and speed of the lower wheel motor of the ball squeezing device and send them to the main control module; The main control module is used to output a PWM signal of a required duty cycle to the upper wheel motor module in a PID control manner according to the received current of the upper wheel motor of the ball squeezing, so as to drive the upper wheel motor of the ball squeezing to operate; the main control module is also used to output a PWM signal of a required duty cycle to the lower wheel motor module in a PID control manner according to the received current of the lower wheel motor of the ball squeezing, so as to drive the lower wheel motor of the ball squeezing to operate; The main control module is also used to judge whether the upper wheel motor of the squeezing ball has been started or accelerated to the target speed of the upper wheel motor according to the received speed of the upper wheel motor of the squeezing ball, and to judge whether the lower wheel motor of the squeezing ball has been started or accelerated to the target speed of the lower wheel motor according to the received speed of the lower wheel motor of the squeezing ball, and then adjust the PWM signal output to the upper wheel motor module and the lower wheel motor module according to the judgment result.

2. The tennis ball machine squeezing wheel control system according to claim 1, characterized in that: The upper wheel motor module includes a first auxiliary control module, a first brake module, a ball-squeezing upper wheel motor, an upper wheel current detection module and an upper wheel speed encoder; The first auxiliary control module is connected to the main control module and is used to receive the PWM signal sent by the main control module; the first auxiliary control module is connected to the first braking module and the upper wheel motor of the ball squeezing ball and is used to control the operation of the upper wheel motor of the ball squeezing ball, and is also used to control the deceleration braking of the upper wheel motor of the ball squeezing ball through the first braking module; the upper wheel current detection module is used to detect the operating current of the upper wheel motor of the ball squeezing ball and send it to the main control module, and the upper wheel speed encoder is used to detect the rotational speed of the upper wheel motor of the ball squeezing ball and send it to the main control module.

3. The tennis ball machine squeezing wheel control system according to claim 2, characterized in that: The lower wheel motor module includes a second auxiliary control module, a second brake module, a ball-squeezing lower wheel motor, a lower wheel current detection module and a lower wheel speed encoder; The second auxiliary control module is connected to the main control module and is used to receive the PWM signal sent by the main control module; the second auxiliary control module is connected to the second braking module and the lower wheel motor of the ball squeezing ball and is used to control the operation of the lower wheel motor of the ball squeezing ball, and is also used to control the deceleration braking of the lower wheel motor of the ball squeezing ball through the second braking module; the lower wheel current detection module is used to detect the operating current of the lower wheel motor of the ball squeezing ball and send it to the main control module, and the lower wheel speed encoder is used to detect the rotational speed of the lower wheel motor of the ball squeezing ball and send it to the main control module.

4. The tennis ball machine squeezing wheel control system according to claim 2, characterized in that: The first auxiliary control module is implemented by an H half-bridge circuit, the first braking module is implemented by a braking circuit, and the upper wheel current detection module is implemented by a sampling and amplifying circuit.

5. The tennis ball machine squeezing wheel control system according to claim 4, characterized in that: The H half-bridge circuit includes a first field effect transistor and a second field effect transistor, the gate of the first field effect transistor is connected to the first IO port of the main control module, the drain of the first field effect transistor is connected to the positive pole of the motor power supply, the negative pole of the motor power supply is grounded, the source of the first field effect transistor is connected to one end of the ball squeezing upper wheel motor and the drain of the second field effect transistor; the gate of the second field effect transistor is connected to the second IO port of the main control module, and the source of the second field effect transistor is connected to the other end of the ball squeezing upper wheel motor.

6. The tennis ball machine squeezing wheel control system according to claim 5, characterized in that: The braking circuit includes a third field effect tube and a braking resistor, the gate of the third field effect tube is connected to the third IO port of the main control module, the drain is connected to the source of the first field effect tube through the braking resistor, and the source of the third field effect tube is grounded.

7. The tennis ball machine squeezing wheel control system according to claim 5, characterized in that: The sampling and amplifying circuit includes a sampling resistor and a current amplifier, one end of the sampling resistor is connected to the source of the second field effect transistor, and the other end is grounded; the two input ports of the current amplifier are respectively connected to the two ends of the sampling resistor, and the output port is connected to the fourth IO port of the main control module.

8. The tennis ball machine squeezing wheel control system according to claim 3, characterized in that: The main control module is configured with a startup program and an acceleration program, and the process of the startup program and the acceleration program is as follows: Output full duty cycle PWM signal to the upper wheel motor module and the lower wheel motor module to control the upper wheel motor and the lower wheel motor of the ball squeezing device to start or accelerate; Receive the running current of the upper wheel motor of the ball squeezing device detected by the upper wheel current detection module and the running current of the lower wheel motor of the ball squeezing device detected by the lower wheel current detection module; According to the received running current, the running current of the upper wheel motor and the lower wheel motor of the ball squeezing device is controlled by PID control, and a PWM signal with a required duty cycle is output so that the running current is maintained at a preset target current; Outputting the PWM signal of the required duty cycle to the upper wheel motor module and the lower wheel motor module, so as to control the operation of the upper wheel motor and the lower wheel motor of the ball squeezing device by using the PWM signal of the required duty cycle; The rotation speeds of the upper wheel motor and the lower wheel motor detected by the upper wheel speed encoder and the lower wheel speed encoder are obtained, and when it is determined that the obtained rotation speed reaches the first target rotation speed, the startup or acceleration program is exited.

9. The tennis ball machine squeezing wheel control system according to claim 3, characterized in that: The main control module is equipped with a deceleration and braking program, and the process of the deceleration and braking program is as follows: Turn off the power supply of the motor, control to open the first brake module and the second brake module, and the motor current is braked through the first brake module and the second brake module; The rotation speeds of the upper wheel motor and the lower wheel motor detected by the upper wheel speed encoder and the lower wheel speed encoder are obtained, and when it is determined that the obtained rotation speed reaches the second target rotation speed, the deceleration and braking program is exited.

10. A method for controlling a ball squeezing wheel of a tennis ball serving machine based on the ball squeezing wheel control system of any one of claims 1 to 9, characterized in that: Including starting process, acceleration process and deceleration braking process; The startup process and acceleration process include the following steps: The main control module outputs a full duty cycle PWM signal to the upper wheel motor module and the lower wheel motor module to control the ball squeezing upper wheel motor in the upper wheel motor module and the ball squeezing lower wheel motor in the lower wheel motor module to start or accelerate; The upper wheel current detection module detects the running current of the upper wheel motor of the squeezing ball, and the lower wheel current detection module detects the running current of the lower wheel motor of the squeezing ball, and feeds back the detected running current to the main control module; The main control module uses PID control to output PWM signals with the required duty cycle to the upper wheel motor module and the lower wheel motor module according to the received running current; The first auxiliary control module in the upper wheel motor module and the second auxiliary control module in the lower wheel motor module control the operation of the upper wheel motor and the lower wheel motor of the ball squeezing device according to the received PWM signal of the required duty cycle; The upper wheel speed encoder detects the speed of the upper wheel motor of the squeezing ball, and the lower wheel speed encoder detects the speed of the lower wheel motor of the squeezing ball, and feeds the detected speed back to the main control module; The main control module compares the acquired rotation speed with a preset first target rotation speed, and exits the startup or acceleration procedure if the acquired rotation speed reaches the first target rotation speed; The deceleration braking process comprises the following steps: The main control module controls the first brake module and the second brake module to open respectively through the first auxiliary control module and the second auxiliary control module, so as to brake the upper wheel motor and the lower wheel motor of the squeezing ball; The upper wheel speed encoder detects the speed of the upper wheel motor of the squeezing ball, and the lower wheel speed encoder detects the speed of the lower wheel motor of the squeezing ball, and feeds the detected speed back to the main control module; The main control module compares the acquired rotation speed with a preset second target rotation speed, and exits the deceleration braking procedure if the acquired rotation speed reaches the second target rotation speed.

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