Portable football field football rebound rate detector

Abstract

The invention belongs to the technical field of rebound testing, and particularly relates to a portable football field football rebound rate detector which comprises a bottom frame, an upper frame and a sensor used for detecting football rebound, a plurality of supporting rods are fixedly connected to the upper side wall of the bottom frame, and a circular ring is fixed to the upper ends of the supporting rods jointly. The circular ring is connected with the upper frame through a connecting rod, a ball lifting and discharging mechanism is arranged in the upper frame, a return pipe is connected between the bottom frame and the upper frame, and a pushing mechanism for pushing a football to move along the return pipe and then enter the upper frame is arranged on the circular ring. By arranging the lifting and ball feeding mechanism, bearing and releasing of a football are achieved, automatic putting of the football is completed, rebound rate detection work is conducted, after detection work is finished, automatic recovery of the football is achieved through the pushing mechanism, continuous detection work can be achieved, the whole device can move through contact between rolling wheels and the ground, movement is convenient, and the detection efficiency is improved. Meanwhile, the backflow pipe is detachably connected with the bottom frame and the upper frame, so that the whole device is more portable.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rebound testing, in particular to a portable football field football rebound rate detector. BACKGROUND

[0002] The rebound rate (sometimes also called the rebound rate or ball rebound height ratio) of a football field is one of the key indicators of the performance of the field surface, directly affecting the movement characteristics of football, such as bounce height, trajectory predictability and rolling speed. A standard rebound rate is essential to ensure the fairness and consistency of the game, as well as the player's control, passing and shooting techniques. A rebound rate that is too high can make the ball difficult to control and the game too fast; a rebound rate that is too low can make the ball roll slowly and the bounce weak, affecting the smoothness and attractiveness of the game.

[0003] The rebound rate of a football field is a core indicator of field certification, directly affecting the fairness of the game and the dynamics of the ball. The traditional detector has the following bottlenecks or defects: Efficiency bottleneck: manual ball picking is required for single detection, with an operation interval of > 2 minutes, which cannot meet the intensive point detection requirements of international football match certification (standard field requires 9 point detection); Mobility obstacle: the overall structure weighs more than 20 kg, relies on transport vehicles for transportation, and the rigid base cannot adapt to the slope changes (> 3°) of natural grass.

[0004] After searching, Chinese patent CN105527187A discloses a portable football field football rebound rate detector, which comprises a support, a sensor mounted on the support, an adsorption and release device, the adsorption and release device is provided with a suction cup, the cavity of the suction cup is matched with the arc surface of the football, and the suction cup is communicated with the suction device through a connecting pipe; the support is an assembled support. Compared with the prior art, the device has the following advantages: the upper and lower lifting assemblies are not provided on the support, the number of components is reduced, the weight of the detector is reduced, the structure of the device is simplified, the weight is reduced, and the device is more convenient to carry and use; but there are the following problems: The suction cup is used to adsorb and release the football to complete the test of the football rebound rate, but the football cannot be recovered after a single test, and the football rebound rate cannot be continuously tested unless the football is manually placed, which is inconvenient.

[0005] To solve the above problems, we propose a portable football field football rebound rate detector. SUMMARY

[0006] The present application relates to the technical field of rebound testing, in particular to a portable football field football rebound rate detector.

[0007] In order to achieve the above object, the application adopts the following technical scheme: a portable football field football rebound rate detector, comprising a bottom frame, an upper frame and a sensor for detecting football rebound, the upper side wall of the bottom frame is fixedly connected with a plurality of supporting rods, the upper ends of the plurality of supporting rods are commonly fixed with a circular ring, the circular ring is connected with the upper frame through a connecting rod, a ball lifting mechanism is arranged in the upper frame, a reflux pipe is connected between the bottom frame and the upper frame, a pushing mechanism is arranged on the circular ring to push the football to move along the reflux pipe and then enter the upper frame, The football is released by the ball lifting mechanism, falls into the bottom frame, contacts with the ground and rebounds, after the football is stabilized, the football is pushed into the reflux pipe by the pushing mechanism, moves to the end of the reflux pipe and then falls into the ball lifting mechanism, so that continuous detection is realized.

[0008] In the above-mentioned portable football field football rebound rate detector, the outer walls of the two ends of the reflux pipe are fixedly connected with connecting blocks, the connecting blocks are fixed on the outer walls of the bottom frame and the upper frame through bolts one and bolts two, a ball outlet is arranged at the connection between the bottom frame and the reflux pipe, a ball inlet gap is arranged at the connection between the upper frame and the reflux pipe, and the end of the reflux pipe is provided with a tangent surface abutting against the ground.

[0009] In the above-mentioned portable football field football rebound rate detector, the ball lifting mechanism comprises a right-angle fixed plate fixed on the outer wall of the upper frame, an electric telescopic rod is fixed at the end of the right-angle fixed plate, a disc is fixed at the driving end of the electric telescopic rod, a load ring for loading the football is fixedly connected with the lower side wall of the disc through a vertical rod, a torsional spring shaft is mounted on the outer wall of the load ring, a load plate is fixed on the outer wall of the torsional spring shaft, a pull rope is fixedly connected between the lower side wall of the load plate and the outer wall of the circular ring, and the sensor is vertically installed on the lower side wall of the disc.

[0010] In the above-mentioned portable football field football rebound rate detector, the vertical rods are staggered with the ball inlet gap.

[0011] In the above-mentioned portable football field football rebound rate detector, the pushing mechanism comprises an electric motor fixed on the outer wall of the circular ring, a right-angle push plate is fixedly connected at the driving end of the electric motor, a ball pushing gap is formed in the outer wall of the bottom frame, and the width of the ball pushing gap is consistent with the width of the right-angle push plate.

[0012] In the above-mentioned portable football field football rebound rate detector, a stop block is fixedly arranged on the outer wall of each side of the right-angle push plate.

[0013] In the above-mentioned portable football field football rebound rate detector, a plurality of connecting columns are fixed on the side of the right-angle push plate away from the bottom frame, and a roller is mounted at the end of each connecting column.

[0014] The outer wall of the reflux pipe is fixed with an auxiliary pipe arranged vertically, the outer wall of the auxiliary pipe is fixed with an air pump, and the output end of the air pump is located in the auxiliary pipe and arranged vertically upward.

[0015] In the portable football field football rebound rate detector, the sensor is an ultrasonic sensor.

[0016] Compared with the prior art, the portable football field football rebound rate detector has the following advantages: 1. The reflux pipe is connected with the bottom frame and the upper frame through the bolt I and the bolt II, and after the detection is completed, the reflux pipe can be separately disassembled and placed, thereby reducing the overall occupied area and making the whole more portable. 2. The ball lifting mechanism is arranged, and under the torsional force of the torsion spring shaft, the bearing plate rotates upward to lift the football. During the detection work, the driving end of the electric telescopic rod is retracted upward, the bearing ring and the bearing plate are moved upward by the vertical rod, and the circular ring cannot move upward. After the pull rope is straightened, the end of the pull rope pulls the end of the bearing plate downward as the bearing plate moves upward, so that the distance gap between the plurality of bearing plates increases, and is greater than the diameter of the football. After that, the football falls out of the plurality of bearing plates, and the automatic falling out of the football is realized. 3. The reflux pipe and the pushing mechanism are arranged, after the single detection work is completed, the electric motor drives the right-angle push plate to rotate from the outer side to the bottom frame side, the right-angle push plate contacts the football, and the football is pushed into the reflux pipe through the ball outlet and moves to the end of the reflux pipe. After that, the football falls out of the end of the reflux pipe into the upper frame and then falls into the bearing ring for bearing, so that the automatic recovery of the football is realized, and the football does not need to be manually placed, and the rebound rate detection work can be continuously performed. 4. The auxiliary pipe and the air pump are arranged, so as to avoid the problems of insufficient pushing force of the right-angle push plate or kinetic energy loss caused by friction between the football and the inner wall of the reflux pipe, so that the football cannot continue to move forward or the power for continuing to move forward is insufficient. When the football moves to the upper side of the auxiliary pipe, the air pump sprays compressed air, which contacts the football and pushes the football to continue to move upward, and then falls out of the end of the reflux pipe into the upper frame, so that the automatic recovery of the football is realized. In summary, the ball lifting mechanism is arranged to realize the bearing and release of the football, the automatic feeding of the football is realized, the automatic recovery of the football is realized by the pushing mechanism after the detection work is completed, the continuous detection work is realized, the device as a whole can be moved by the contact between the rollers and the ground, the movement is convenient, and the reflux pipe can be disassembled from the bottom frame and the upper frame, so that the whole device is more portable. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1An external structure schematic view of a portable football field football rebound rate detector according to the present application is provided; Figure 2 A state schematic view of a portable football field football rebound rate detector according to the present application is provided when the right angle push plate is turned out. Figure 3 A structure schematic view of a portable football field football rebound rate detector according to the present application is provided at the connection between the upper frame and the ball lifting mechanism. Figure 4 A state schematic view of a portable football field football rebound rate detector according to the present application is provided when the ball lifting mechanism lifts the football. Figure 5 A structure schematic view of a portable football field football rebound rate detector according to the present application is provided for the ball lifting mechanism. Figure 6 A structure schematic view of a portable football field football rebound rate detector according to the present application is provided for the return pipe. Figure 7 A structure schematic view of a portable football field football rebound rate detector according to the present application is provided for the connection between the bottom frame and the support rod. Figure 8 A structure schematic view of a portable football field football rebound rate detector according to the present application is provided for the circular ring. Figure 9 A structure schematic view of a portable football field football rebound rate detector according to the present application is provided for the right angle push plate.

[0018] In the figure: 1 bottom frame, 2 support rod, 3 circular ring, 4 connecting rod, 5 upper frame, 6 return pipe, 7 right angle fixed plate, 8 electric telescopic rod, 9 disc, 10 vertical rod, 11 bearing ring, 12 pull rope, 13 connecting block, 14 bolt one, 15 bolt two, 16 motor, 17 right angle push plate, 18 connecting column, 19 roller, 20 stop block, 21 auxiliary pipe, 22 air pump, 23 bearing plate, 24 ball outlet, 25 cutting surface. DETAILED DESCRIPTION

[0019] The following examples are for illustrative purposes only and are not intended to limit the scope of the present application.

[0020] REFERENCE Figures 1-9The utility model provides a portable football ground football rebound rate detector, including bottom frame 1, upper frame 5 and be used for detecting football rebound sensor, the upper side wall of bottom frame 1 is fixedly connected with a plurality of support bars 2, the upper end of a plurality of support bars 2 is jointly fixed with ring 3, ring 3 is connected with upper frame 5 through connecting rod 4, the outer wall of both ends of backflow pipe 6 is fixedly connected with connecting block 13, connecting block 13 is fixed on the outer wall of bottom frame 1 and upper frame 5 through bolt one 14 and bolt two 15 respectively, the connecting place of bottom frame 1 and backflow pipe 6 is provided with ball outlet 24, the connecting place of upper frame 5 and backflow pipe 6 is provided with ball inlet gap, the end of backflow pipe 6 is provided with the tangent plane 25 that grounds is pasted together, setting bolt one 14, bolt two 15 and connecting block 13 realize the connection of both ends of backflow pipe 6 and bottom frame 1 and upper frame 5, after detection, backflow pipe 6 can be separately taken down and be placed, reduce the area that occupies as a whole, make as a whole more convenient to carry, when the connection of backflow pipe 6 and bottom frame 1 and upper frame 5 is also more convenient, through bolt one 14 and bolt two 15 are rotated into to the thread port on the outer wall of bottom frame 1 and upper frame 5 can complete the connection of backflow pipe 6 and bottom frame 1 and upper frame 5, again place as a whole on the grassland of detection, can carry out the rebound work detection of grassland, The tangent plane 25 of the end of backflow pipe 6 enables the end of backflow pipe 6 to be placed in close contact with the ground, ensuring the stability of the entire detection device.

[0021] The upper frame 5 is provided with a ball lifting mechanism, the ball lifting mechanism includes a right-angle fixed plate 7 fixed to the outer wall of the upper frame 5, an electric telescopic rod 8 fixed to the end of the right-angle fixed plate 7, a disc 9 fixed to the driving end of the electric telescopic rod 8, a load ring 11 fixed to the lower side wall of the disc 9 through a vertical rod 10, the vertical rod 10 is staggered with the ball inlet gap, a torsion spring shaft is installed on the outer wall of the load ring 11, a load plate 23 is fixed to the outer wall of the torsion spring shaft, a pull rope 12 is fixed between the lower side wall of the load plate 23 and the outer wall of the ring 3, a sensor is vertically installed on the lower side wall of the disc 9, a football is placed in the load ring 11 and lifted by the load plate 23, under the action of the torsion of the torsion spring shaft, the load plate 23 rotates upward to lift the football, during the detection work, the driving end of the electric telescopic rod 8 is retracted upward, the load ring 11 and the load plate 23 are pulled upward by the vertical rod 10, the ring 3 cannot move upward, after the pull rope 12 is straightened, with the upward movement of the load plate 23, the end of the pull rope 12 pulls the end of the load plate 23 to rotate downward, the distance between the load plates 23 increases, which is greater than the diameter of the football, the football falls out of the load plates 23, bounces after colliding with the grass, the rebound height of the football is detected by the sensor, and a single detection work is completed.

[0022] Torsion spring rotating shaft: the torsion spring is fixed on the rotating shaft. When the rotating shaft is driven to rotate by external force, the torsion spring is twisted and deformed (the diameter of the spring ring changes), storing elastic potential energy. After the external force disappears, the torsion spring releases energy to drive the rotating shaft back. Bearings and other bearing seats are provided for the installation of the torsion spring rotating shaft. The end of the rotating shaft is installed in the bearing seat. One end of the torsion spring is fixed on the rotating shaft, and the other end is fixed on the outer wall of the bearing seat or the bearing ring 11. The torsion of the torsion spring realizes the storage and release of elastic potential energy, and the up and down rotation of the bearing plate 23, thereby realizing the bearing and release of the football. The rotating shaft needs to maintain a gap with the inner diameter of the torsion spring (recommended shaft diameter ≤ 90% of the inner diameter of the torsion spring) to prevent sticking or friction loss. It is commonly used on structures such as door leaves, and automatic return is achieved through the torsion spring.

[0023] A return pipe 6 is connected between the bottom frame 1 and the upper frame 5. A pushing mechanism is provided on the circular ring 3 to push the football along the return pipe 6 and into the upper frame 5. The pushing mechanism includes a motor 16 fixed on the outer wall of the circular ring 3. The driving end of the motor 16 is fixedly connected with a right-angle push plate 17. A ball pushing gap is formed in the outer wall of the bottom frame 1. The width of the ball pushing gap is the same as the width of the right-angle push plate 17. A vertical auxiliary pipe 21 is fixed on the outer wall of the return pipe 6. A gas pump 22 is fixed on the outer wall of the auxiliary pipe 21. The output end of the gas pump 22 is located in the auxiliary pipe 21 and is vertically upward. After a single detection is completed, the driving end of the electric telescopic rod 8 is extended, and the bearing plate 23 returns to the original position. When the football is stable, the motor 16 is started to drive the right-angle push plate 17 to rotate from the outside to one side of the bottom frame 1. After the right-angle push plate 17 contacts the football, the football is pushed through the ball outlet 24 into the return pipe 6, moves along the return pipe 6 to the end, and falls from the end of the return pipe 6 into the upper frame 5, and then falls into the bearing ring 11 for bearing. The above process can be repeated to detect the rebound rate again without manually taking and placing the football, which is more convenient. When the football moves to the upper side of the end of the auxiliary pipe 21, the gas pump 22 is started to spray high-pressure airflow, which pushes the football to move under the action of the airflow. The problem that the football cannot continue to move forward or has insufficient power to continue to move forward due to insufficient pushing force of the right-angle push plate 17 or friction between the football and the inner wall of the return pipe 6 is avoided. Inductors can be provided on the inner wall of the auxiliary pipe 21. When the football moves to the upper side of the auxiliary pipe 21, the inductors send signals to the controller to start the gas pump 22. The gas pump 22 compresses and sprays air, which contacts the football to push it to continue to move upward, and then falls from the end of the return pipe 6 into the upper frame 5 to realize automatic recovery of the football.

[0024] Gas pump 22 power compensation: solves the problem of football jamming, and ensures that the success rate of transportation in the inclined pipe reaches 99%.

[0025] In order to ensure that the right angle push plate 17 stably pushes the football into the ball outlet 24, an arc-shaped opening corresponding to the position of the ball outlet 24 can be formed on the right angle push plate 17, or an arc-shaped plate corresponding to the position of the ball outlet 24 is fixed on the end of the right angle push plate 17. When the arc-shaped opening and the arc-shaped plate are in contact with the football, the football has a centering effect, so that the football moves along the path between the ball outlet 24 and the center of the arc-shaped opening or arc-shaped plate, and the football can stably enter the ball outlet 24 and then enter the return pipe 6.

[0026] The right angle push plate 17 is fixed with a plurality of connecting columns 18 on the side away from the bottom frame 1, and each connecting column 18 is provided with a roller 19 at the end. After the detection work is completed, the right angle push plate 17 can be driven to rotate to be vertical by the motor 16, and then the whole device is placed flat so that the rollers 19 are in contact with the ground, and the blocks 20 are in contact with the outer wall of the bottom frame 1, so that the bottom frame 1 and the right angle push plate 17 bear the ground pressure together, and the whole device can be moved.

[0027] After the football is released by the ball lifting mechanism and falls into the bottom frame 1 and is in contact with the ground, it is bounced back. After the football is stable, it is pushed into the return pipe 6 by the pushing mechanism, moves along the return pipe 6 to the end, and then falls out into the ball lifting mechanism, realizing continuous detection.

[0028] Further, in order to reduce the friction between the football and the inner wall of the return pipe 6, the inner wall of the return pipe 6 is sprayed with a PTFE coating (friction coefficient μ≤0.12).

[0029] Further, through tests, when the electric telescopic rod 8 has a stroke of 120 mm, the tension peak of the pull rope 12 is 82 N, and the bearing plate needs only 0.8 seconds to open to the maximum gap of 220 mm, so that the football can be quickly dropped.

[0030] Further, the sensor can be an ultrasonic sensor, or a sensor array: When the object bounces up, the distance between the sensor and the object will gradually decrease (the object approaches the sensor), and the distance is smallest at the highest point, and then increases when the object falls. By continuously measuring and recording the minimum value, the rebound height can be determined. When the distance continuously decreases, start recording, and when the distance first increases, determine the highest point. The speed of sound is affected by temperature, so a temperature sensor can be added for calibration. Measure 3-5 times and take the average value to reduce noise. Use Kalman filtering or moving average to process data fluctuations. Small objects such as small balls may have weak reflected signals, so the sensitivity of the sensor needs to be adjusted or a reflecting plate needs to be added.

[0031] High frame rate camera (120fps) + laser range finder synchronous acquisition, football landing point positioning accuracy ±2mm, rebound height error <1%, high frame rate camera based on YOLOv5 model real-time identification football ellipsoid profile, calculate the centroid projection coordinates, track the football centroid trajectory under high frame rate, construct three-dimensional motion equation, calculate the trajectory curvature through differential algorithm: when dz / dt=0 and d 2 z / dt 2 <0 record the rebound peak, laser range finder uses time: emit infrared laser beam→football surface reflection→receiver calculates time difference→real-time output distance value.

[0032] The application discloses a football automatic closed loop system and a modular quick disassembly and assembly framework, a ball outlet 24 is arranged on a bottom frame 1, a section 25 is laser cut and profiled, and the adhesion of the bottom frame 1 is ensured to be greater than 90% when the inclination is 5°; six supporting rods 2 and a reinforced circular ring 3 form a truss structure, the self weight is only 2.3 kg, the bending strength is greater than or equal to 180 MPa, the inner diameter of a bearing ring 11 is Φ450 mm, a vertical rod 10 is offset by 15° to a ball inlet gap, backflow interference is avoided, the detection efficiency is significantly improved, and the portability is greatly enhanced.

[0033] The application discloses a football automatic closed loop system and a modular quick disassembly and assembly framework, a ball outlet 24 is arranged on a bottom frame 1, a section 25 is laser cut and profiled, and the adhesion of the bottom frame 1 is ensured to be greater than 90% when the inclination is 5°; six supporting rods 2 and a reinforced circular ring 3 form a truss structure, the self weight is only 2.3 kg, the bending strength is greater than or equal to 180 MPa, the inner diameter of a bearing ring 11 is Φ450 mm, a vertical rod 10 is offset by 15° to a ball inlet gap, backflow interference is avoided, the detection efficiency is significantly improved, and the portability is greatly enhanced.

[0034] The application discloses a football automatic closed loop system and a modular quick disassembly and assembly framework, a ball outlet 24 is arranged on a bottom frame 1, a section 25 is laser cut and profiled, and the adhesion of the bottom frame 1 is ensured to be greater than 90% when the inclination is 5°; six supporting rods 2 and a reinforced circular ring 3 form a truss structure, the self weight is only 2.3 kg, the bending strength is greater than or equal to 180 MPa, the inner diameter of a bearing ring 11 is Φ450 mm, a vertical rod 10 is offset by 15° to a ball inlet gap, backflow interference is avoided, the detection efficiency is significantly improved, and the portability is greatly enhanced. 1、the detachable backflow pipe 6 design; 2、 1、the detachable backflow pipe 6 design: the backflow pipe 6 is connected with the bottom frame 1 and the upper frame 5 through the bolt one 14 and the bolt two 15 at both ends, the bolt can adopt a butterfly bolt, has an integrated self-locking ratchet structure, and is manually operated to complete disassembly and assembly within 8 seconds; The connecting block 13 can adopt a conical positioning pin design, so that the repeated installation positioning accuracy is ensured to be ±0.5mm.

[0035] 2、the automatic lifting release mechanism: the bearing ring 11 is driven to move up and down by the electric telescopic rod 8, the football is placed in the bearing ring 11 and is lifted by the bearing plate 23, under the torsion effect of the torsion spring rotating shaft, the bearing plate 23 rotates upwards to lift the football, the driving end of the electric telescopic rod 8 is retracted upwards, the bearing ring 11 and the bearing plate 23 are pulled upwards by the vertical rod 10, the end part of the bearing plate 23 is pulled downwards by the straightened pull rope 12, so that the football falls out of the bearing plate 23, and the football is released; 3. Pneumatic auxiliary recovery system: the air pump 22 adopts pulse jet, single work 8 seconds, power consumption 12 Wh, the inner wall of the backflow pipe 6 is coated with PTFE nano (friction coefficient μ = 0.10), which reduces the resistance by 60% compared with ordinary PVC pipe; the air flow speed of the air pump 22 outlet is 25 m / s, which provides an additional thrust of ≥ 15 N, the inclination angle of the auxiliary pipe 21 is 30° ± 1°, and the centrifugal force of the football bending is reduced by 40%; 4. Portable moving mechanism: the whole body is tilted by 90°, so that the whole body is moved through the roller 19, the position of the whole body is adjusted, the roller 19 adopts a polyurethane rubber-encased wheel to reduce the moving resistance, the lawn dragging resistance is < 50 N, and the length of the connecting column 18 can be adjusted to adapt to different operator heights.

[0036] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A portable football rebound rate detector for a football field, comprising a base frame (1), an upper frame (5), and a sensor for detecting football rebound, characterized in that, The upper side wall of the bottom frame (1) is fixedly connected with multiple support rods (2), and the upper ends of the multiple support rods (2) are fixed with a ring (3). The ring (3) is connected to the upper frame (5) through a connecting rod (4). The upper frame (5) is provided with a ball-lifting mechanism. A return pipe (6) is connected between the bottom frame (1) and the upper frame (5). The ring (3) is provided with a pushing mechanism that pushes the football along the return pipe (6) and into the upper frame (5). After the football is released by the ball-lifting mechanism, it falls into the bottom frame (1) and bounces after contacting the ground. After the football stabilizes, it is pushed into the return pipe (6) by the pushing mechanism. After moving along the return pipe (6) to the end, it falls out into the ball-lifting mechanism, thus realizing continuous detection.

2. The portable football rebound rate detector for a football field according to claim 1, characterized in that, Connecting blocks (13) are fixedly connected to the outer walls of both ends of the return pipe (6). The connecting blocks (13) are fixed to the outer walls of the bottom frame (1) and the top frame (5) respectively by bolt one (14) and bolt two (15). A ball outlet (24) is provided at the connection between the bottom frame (1) and the return pipe (6). A ball inlet is provided at the connection between the top frame (5) and the return pipe (6). A ball inlet is provided at the connection between the top frame (5) and the return pipe (6). The end of the return pipe (6) is provided with a cut surface (25) that fits with the ground.

3. The portable football rebound rate detector for a football field according to claim 2, characterized in that, The ball-lifting mechanism includes a right-angle fixing plate (7) fixed on the outer wall of the upper frame (5). An electric telescopic rod (8) is fixed at the end of the right-angle fixing plate (7). A disc (9) is fixed at the driving end of the electric telescopic rod (8). A bearing ring (11) for carrying a football is fixedly connected to the lower side wall of the disc (9) through a vertical rod (10). A torsion spring shaft is installed on the outer wall of the bearing ring (11). A bearing plate (23) is fixed on the outer wall of the torsion spring shaft. A pull rope (12) is fixedly connected between the lower side wall of the bearing plate (23) and the outer wall of the ring (3). The sensor is installed vertically downward on the lower side wall of the disc (9).

4. The portable football rebound rate detector for a football field according to claim 1, characterized in that, The vertical rod (10) is staggered from the goal opening.

5. A portable football rebound rate detector for a football field according to claim 1, characterized in that, The pushing mechanism includes a motor (16) fixed on the outer wall of the ring (3). The driving end of the motor (16) is fixedly connected to a right-angle push plate (17). A ball-pushing notch is opened on the outer wall of the bottom frame (1). The width of the ball-pushing notch is the same as the width of the right-angle push plate (17).

6. A portable football rebound rate detector for a football field according to claim 5, characterized in that, The right-angle push plate (17) has symmetrically fixed blocks (20) on its two outer walls.

7. A portable football rebound rate detector for a football field according to claim 5, characterized in that, The right-angle push plate (17) is fixed with a plurality of connecting posts (18) on the side away from the bottom frame (1), and each of the connecting posts (18) is equipped with a roller (19) at its end.

8. A portable football rebound rate detector for a football field according to claim 1, characterized in that, An auxiliary pipe (21) is fixed on the outer wall of the return pipe (6) and is arranged vertically. An air pump (22) is fixed on the outer wall of the auxiliary pipe (21) and the output end of the air pump (22) is located inside the auxiliary pipe (21) and is arranged vertically upward.

9. A portable football rebound rate detector for a football field according to claim 1, characterized in that, The sensor is an ultrasonic sensor.

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