Tail end grabbing mechanism for basketball robot

Abstract

The invention relates to the field of robots, in particular to a tail end grabbing mechanism for a basketball robot, which comprises a mounting plate and a plurality of clamping jaws, the mounting plate is provided with a central axis, and the plurality of clamping jaws are uniformly arranged around the central axis; the clamping jaw is provided with a connecting end and a tail end, the connecting end is rotationally connected with the mounting plate, and the tail end is a free end; a motor is arranged on the mounting plate, a connecting plate is arranged on an output shaft of the motor, each clamping jaw is connected with the connecting plate through a fisheye bearing, each fisheye bearing comprises a bearing rod and two bearing balls, and the two bearing balls are arranged at the two ends of the bearing rod respectively and can rotate relative to the bearing rod. The clamping jaw and the connecting plate are connected with the bearing balls at the two ends of the bearing rod respectively. The clamping jaws and the connecting plate are connected through the fisheye bearings, machining and assembling errors are compensated and over-constraint is eliminated by means of the multi-degree-of-freedom characteristic of the fisheye bearings, the grabbing mechanism is made to move without clamping stagnation, all the clamping jaws are driven by one driving piece through the fisheye bearings, and accurate synchronization of the clamping jaws is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of robotics, and more specifically, to an end effector for a basketball robot. Background Technology

[0002] The development of basketball robots is an important branch of robotics technology applied in practical sports. One of its core functions is to reliably grasp and release basketballs. The performance of the end effector directly determines the success rate and stability of the basketball robot's catching, holding, and shooting of the ball.

[0003] Currently, most basketball robot end effector grasping mechanisms employ linkage mechanisms or linear guide mechanisms. In linkage mechanisms, a drive motor drives multiple sets of links via a central disk. The other end of each link is hinged to a gripper, converting the motor's rotational motion into the gripper's opening and closing motion. However, this traditional rigid linkage hinge method has inherent technical drawbacks: First, due to machining precision, assembly errors, and the influence of micro-deformation of structural components after long-term use, it is difficult to guarantee the ideal geometric relationship of all moving parts. Traditional hinges (such as single-pin connections) only provide a single degree of rotational freedom. When the rotation planes of multiple grippers are slightly non-parallel to the rotation plane of the central disk, the linkage mechanism becomes an over-constrained system. This over-constraint generates significant internal stress at the hinge points, leading to uneven movement, jamming, abnormal wear, and noise. This not only reduces the success rate of grasping but also shortens the mechanism's lifespan. Second, the over-constraint problem places extremely high demands on the precision of the control system and the performance of the motor. The motor needs to output greater torque to overcome the friction and jamming within the mechanism, which not only increases energy consumption but may also lead to motor overheating or damage. Simultaneously, jamming makes the mechanism's movement unpredictable, making it difficult for the controller to precisely control the final position and gripping force of the grippers, thus affecting gripping stability. Furthermore, in scenarios requiring strictly synchronized movement of multiple grippers, jamming at any hinge point will disrupt this synchronization, resulting in uneven gripping force on the basketball, potentially causing the basketball to slip from the side with weaker gripping force. Summary of the Invention

[0004] The present invention aims to overcome at least one of the defects (deficiencies) of the prior art and provide an end effector for basketball robots, which solves the problem that the linkage structure of the existing end effector is an over-constrained system due to the influence of machining accuracy, assembly error and micro deformation of structural components after long-term use.

[0005] The technical solution adopted by this invention is an end effector for a basketball robot, comprising a mounting plate and multiple grippers. The mounting plate has a central axis, and the multiple grippers are evenly arranged around the central axis. Each gripper has a connecting end and an end end. The connecting end is rotatably connected to the mounting plate, and the end end is a free end. A motor is mounted on the mounting plate, and a connecting plate is mounted on the output shaft of the motor. Each gripper is connected to the connecting plate via a fisheye bearing. The fisheye bearing includes a bearing rod and two bearing balls, which are respectively disposed at both ends of the bearing rod and can rotate relative to the bearing rod. The grippers and the connecting plate are respectively connected to the bearing balls at both ends of the bearing rod.

[0006] By employing fisheye bearings with ball bearings at both ends to connect the grippers and the connecting plate, the multi-degree-of-freedom motion characteristics automatically compensate for errors caused by machining, assembly, and deformation, fundamentally eliminating over-constraint. This results in smoother, more seamless movement of the mechanism, significantly improving reliability and service life. All grippers are synchronously driven by a single drive component (connecting plate) via fisheye bearings. Combined with the error compensation capability of the fisheye bearings, precise synchronization of all gripper movements is ensured, achieving a uniform and stable grip on the basketball with a high success rate. Furthermore, its smooth motion characteristics reduce the requirements for motor performance and control algorithms, while also reducing the stringent requirements for component machining and assembly precision, making the overall system more economical.

[0007] Elastic components are interlocked among multiple grippers, allowing them to stabilize in a pre-catch position slightly smaller than the basketball's diameter, aided by a motor. This transforms the impact of the basketball into a squeezing motion, creating a guiding mechanism that significantly improves the success rate and fault tolerance of the gripping mechanism. The elastic components effectively absorb the impact energy of the basketball, converting a rigid collision into a compliant grip. This protects both the basketball and the gripping mechanism, while the passive fine-tuning of the grippers enables an adaptive envelope of the basketball. Furthermore, the restoring force of the elastic components ensures that the gripping mechanism automatically and reliably holds the basketball in the event of a drive system failure or power outage, preventing accidental drops and enhancing the overall safety and reliability of the device.

[0008] When the fisheye bearing connects to the connecting plate, a connection point is formed. The projection of the bearing rod of the fisheye bearing onto the connecting plate forms an angle α with the tangent direction of the motion trajectory at the connection point. This angle α decreases as the gripper closes. On the connecting plate or a plane parallel to the connecting plate, the force exerted by the bearing rod on the gripper can be decomposed into an effective component along the tangent direction of the motion trajectory at the connection point and an ineffective component along the radial direction. In the pre-receiving state, setting the angle α to 20-40 degrees maintains a high level of effective force. This means that at the moment of receiving the ball, the impact energy of the basketball or the driving force of the motor can be efficiently converted into the torque driving the gripper to rotate, thus giving the mechanism a high response sensitivity. If the angle α is greater than 40 degrees, the effective force will decrease, causing the gripping mechanism to react sluggishly in this state and failing to achieve fast and reliable triggering. If the angle is less than 20 degrees, although the theoretical effective force is greater, it will result in a short closing stroke of the gripping mechanism and significantly weaken its motion stability and reliability.

[0009] On a plane perpendicular to the connecting plate, the angle α1 between the projection of the bearing rod and the gripper increases as the gripper closes. On the plane perpendicular to the connecting plate, the force exerted by the bearing rod on the gripper can be decomposed into a component perpendicular to the gripper's rotation radius and a force along the gripper's rotation radius. The component perpendicular to the gripper's rotation radius generates the torque that drives the gripper to rotate and is the effective component; the component along the gripper's rotation radius only exerts positive pressure on the shaft and does no work, and is the ineffective component. In the pre-receiving state, setting the angle α1 to 60-80 degrees results in a larger effective component, enabling extremely high force transmission efficiency and motion response speed at the moment of ball reception. If the angle α1 is less than 60 degrees, the force transmission efficiency will be significantly reduced, leading to a sluggish mechanism response in the pre-receiving state, making fast and reliable gripping impossible. However, if the included angle a1 is greater than 80 degrees, although it can make the effective component force greater, it will result in the required closed working stroke of the gripping mechanism being too short and significantly increase the sensitivity to manufacturing precision and rigidity, thereby impairing the reliability and stability of the gripping process.

[0010] The length of the bearing rod of the fisheye bearing is adjustable. By adjusting the length of the bearing rod, manufacturing and assembly errors can be precisely compensated, ensuring the synchronization of multiple grippers and the uniformity of gripping, thus structurally guaranteeing gripping stability. Furthermore, by adjusting the length of the bearing rod, the gripping mechanism can adapt to basketballs of different sizes, improving the mechanism's versatility and adaptability. The length of the bearing rod can be adjusted via threads, telescopic mechanisms, or other means.

[0011] The gripper consists of a straight section, an arc section, and a bent section from the connecting end to the end. The bent section is located at the end of the gripper and has a rotatable guide wheel. When the basketball contacts the guide wheel, the guide wheel rolls to accommodate deviations. Even if the basketball does not hit the center, the guide wheel can still guide it into the preset gripping space, thereby further improving the success rate and error tolerance of dynamic ball reception and reducing the requirement for the accuracy of the basketball's rebound trajectory. In addition, when the gripper moves relative to the basketball surface (especially during the guiding phase of the basketball's entry), the rolling of the guide wheel replaces the sliding of the gripper end, allowing the basketball to enter the open gripper space more smoothly and effortlessly, while effectively avoiding scratches on the basketball surface that may be caused by sliding friction. By bending the bent section relative to the arc section in a direction away from the central axis (defined as outward), when the basketball squeezes the guide wheel, it generates a torque that is more conducive to the overall outward opening of the gripper, thereby reducing the force required for the basketball to enter the gripping space and making the ball reception process smoother. The bent section bends outward relative to the arc section to form a protrusion. To prevent the basketball from being stuck by the protrusion after being squeezed into the guide wheel, the net distance between the protrusion and the central axis needs to be set to be greater than the net distance between the guide wheel and the central axis. That is, when the gripper opens, the diameter of the first virtual circle formed by all the protrusions is greater than the diameter of the second virtual circle formed by all the guide wheels.

[0012] The curved section of the gripper faces the central axis (defined as inward) with an arc-shaped surface, and multiple grippers have these arc-shaped surfaces distributed along the same hemisphere. This design allows multiple arc-shaped surfaces to collectively form a near-spherical enclosing space. When the grippers close, these arc-shaped surfaces can simultaneously and evenly wrap around the basketball from multiple directions. Compared to flat surfaces or sharp edges, this significantly increases the contact area between the grippers and the basketball, resulting in a more even distribution of gripping force. This protects the basketball's surface while also making the grip more stable. Furthermore, the geometric relationship between the arc-shaped surface and the spherical surface provides greater restraint. During arm swings and throwing motions, this design effectively prevents slight slippage or rotation of the basketball, making the movements more precise.

[0013] A buffer pad is installed on the connecting plate to limit and cushion the impact, preventing rigid collisions between the basketball and the connecting plate. When the grippers are facing upwards, the buffer pad provides support. The side of the buffer pad facing the end of the grippers is designed with a curved concave surface, which provides a certain degree of limitation, making the grip more stable and improving the accuracy when swinging the arm or throwing.

[0014] Compared to three grippers, with the same total clamping force, four to six grippers can distribute the gripping force more evenly across the basketball surface, effectively avoiding excessive local pressure caused by too few grippers, thus better protecting the basketball's airtightness and surface integrity. On the other hand, with only three grippers, when the grippers are in preparation to open, the elastic components form a straight line between every two grippers, making the preparatory profile triangular. This results in a smaller effective capture diameter (i.e., the diameter of the inscribed circle), which may affect the normal entry of the basketball. When the number of grippers increases to four to six, the preparatory profile is closer to a complete circle, greatly eliminating the straight-edge effect, making the effective capture diameter closer to its theoretical maximum. With three grippers, the basketball may also slip out between the grippers, leading to unstable gripping. However, if the number of grippers exceeds six, the structural complexity and cost increase dramatically. Furthermore, more moving parts mean greater inertia and more internal friction, which can slow down the system's response in dynamic ball-catching scenarios requiring rapid opening and closing. Therefore, the number of grippers is set to 4-6.

[0015] Compared with existing technologies, the advantages of this invention are as follows: By using fisheye bearings with ball bearings at both ends to connect the grippers and the connecting plate, the multi-degree-of-freedom motion characteristics are utilized to compensate for errors caused by machining, assembly, and deformation, fundamentally eliminating over-constraint. This makes the gripping mechanism move smoothly and without jamming, significantly improving reliability and service life. All grippers are synchronously driven by a single drive component (connecting plate) via fisheye bearings, and the error compensation capability of the fisheye bearings ensures precise synchronization of the movement of all grippers. Elastic components are set between multiple grippers to connect them, allowing the grippers to stabilize in a ready-to-receive state slightly smaller than the diameter of the basketball, transforming the collision of the basketball into a squeezing motion, forming a guiding mechanism, which greatly improves the success rate and fault tolerance of folding. The restoring force of the elastic components also ensures that the gripping mechanism can automatically and reliably hold the basketball in the event of drive system failure or power failure, preventing accidental drops. In the ready-to-receive state, setting the included angle α to 20-40 degrees ensures that the force exerted by the fisheye bearing on the gripper has a high effective component on the connecting plate or a plane parallel to the connecting plate, giving the gripping mechanism high responsiveness and sufficient closed-loop stroke. Setting the included angle α1 to 60-80 degrees ensures that the force exerted by the fisheye bearing on the gripper has a high effective component on a plane perpendicular to the connecting plate. To compensate for manufacturing and assembly errors and ensure the synchronization and uniformity of gripping among multiple grippers, the length of the bearing rod is adjustable. Adjusting the bearing rod length also allows the gripping mechanism to adapt to basketballs of different sizes, improving its versatility and adaptability. A rotatable guide wheel is provided at the end of the gripper, transforming the sliding friction between the basketball and the gripper end into rolling friction between the basketball and the guide wheel. This allows the basketball to enter the gripping space more smoothly and effortlessly, while also preventing scratches on the basketball surface. The guide wheel can adapt to deviations through rolling, guiding the basketball into the gripping space, improving the success rate and error tolerance of the catch. The outward bending of the bend section generates a torque that facilitates the outward opening of the grippers when the basketball presses against the guide wheel, reducing the force required for the basketball to squeeze into the gripping space and making the receiving process smoother. To prevent the basketball from being stuck by the protrusion during the squeezing process, the net distance between the protrusion and the central axis is set to be greater than the net distance between the guide wheel and the central axis. The curved surfaces of multiple grippers are distributed along the same hemisphere, allowing them to collectively form a near-spherical enclosing space. When the grippers close, they evenly wrap around the basketball, increasing the contact area between the grippers and the basketball and distributing the gripping force evenly. At the same time, the curved surfaces provide greater restraint between the basketball and the spherical surface of the basketball. This design effectively prevents slight slippage or rotation of the basketball during arm swings and throws, making the action more precise. The buffer pad on the connecting plate provides cushioning and support. The side of the buffer pad facing the end of the gripper is designed as a concave curved surface, which provides a certain degree of limiting. Four to six grippers can achieve the best balance between gripping stability, adaptability to basketball surfaces, and control complexity. Attached Figure Description

[0016] Figure 1 This is a structural diagram of the present invention.

[0017] Figure 2 This is a structural diagram of the present invention from another angle.

[0018] Figure 3 This is a side view of the present invention.

[0019] Figure 4 This is a bottom view of the present invention.

[0020] Figure 5 This is a structural diagram of a fisheye bearing.

[0021] Figure 6 This is an exploded view of a fisheye bearing.

[0022] Figure 7 This is a structural diagram of the present invention mounted on a robotic arm.

[0023] 100. Mounting plate; 110. Central axis; 120. First rotating shaft; 200. Gripper; 210. Straight section; 220. Arc-shaped section; 221. Arc-shaped surface; 230. Bending section; 240. Protrusion; 300. Motor; 400. Drive mechanism; 410. Connecting plate; 420. Fisheye bearing; 421. Bearing rod; 4211. First bearing rod; 4212. Second bearing rod; 4213. Bearing outer ring; 422. Bearing ball; 4221. Through hole; 423. Connecting shaft; 500. Buffer pad; 510. Arc-shaped concave surface; 600. Guide wheel; 610. Second rotating shaft; 620. Annular groove; 700. Elastic component; 800. Robotic arm. Detailed Implementation

[0024] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the invention. To better illustrate the following embodiments, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions; it is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0025] In the description of this invention, it should be noted that the terms "upper," "lower," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. These terms are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0026] Example 1 like Figure 1 , Figure 2 As shown, an end effector for a basketball robot includes a mounting plate 100 and a plurality of grippers 200. The mounting plate 100 has a central axis 110, and the plurality of grippers 200 are evenly arranged around the central axis 110. Each gripper 200 has a connecting end and a distal end. The connecting end is connected to the mounting plate 100 via a first rotating shaft 120, and the gripper 200 is rotatable around the first rotating shaft 120. The distal end of each gripper 200 is a free end. A gripping space is formed between the plurality of grippers 200. Preferably, there are 4-6 grippers 200.

[0027] A motor 300 is mounted on the mounting plate 100, and the output shaft of the motor 300 is collinear with the central axis 110 of the mounting plate 100. The motor 300 is connected to multiple grippers 200 via a drive mechanism 400. The drive mechanism 400 includes a connecting plate 410 and multiple fisheye bearings 420. The connecting plate 410 is fixed to the output shaft of the motor 300, and one end of each fisheye bearing 420 is connected to the connecting plate 410, while the other end is connected to the grippers 200. When the motor 300 operates, the connecting plate 410 rotates, thereby causing the multiple grippers 200 to rotate synchronously around the first rotating shaft 120 via the fisheye bearings 420, achieving opening and closing. A buffer pad 500 is provided on the connecting plate 410. The buffer pad 500 is trumpet-shaped, with an arc-shaped concave surface 510 on the side facing the end of the gripper 200. The buffer pad 500 serves to limit, buffer, and support, and its material can be silicone, rubber, polyurethane, etc. A sensor (not shown) can be installed on the buffer pad 500. When the basketball touches the buffer pad 500, the motor 300 works, its output shaft reverses, drives the connecting plate 410 to reverse, and causes the gripper 200 to close through the fisheye bearing 420.

[0028] like Figure 5As shown, the fisheye bearing 420 includes a bearing rod 421 and bearing balls 422. The length of the bearing rod 421 is adjustable, and there are two bearing balls 422, respectively disposed at both ends of the bearing rod 421, and they can rotate relative to the bearing rod 421. Figure 3 , Figure 4 As shown, one end of the fisheye bearing 420 is connected to the connecting plate 410, forming a connection point, and the other end is connected to the gripper 200. When the motor 300 drives the connecting plate 410 to rotate, the movement trajectory of the connection point is a circle. The projection of the bearing rod 421 of the fisheye bearing 420 onto the connecting plate 410 forms an angle α with the tangent to the movement trajectory of the connection point; on a plane perpendicular to the connecting plate 410, the projection of the bearing rod 421 forms an angle α1 with the gripper. The gripping mechanism has a pre-catching state, in which the motor 300 drives the gripper 200 to open and maintain an opening, the diameter of which is slightly smaller than the diameter of the basketball. At this time, the angle α is 20-40 degrees, and the angle α1 is 60-80 degrees.

[0029] like Figure 5 , Figure 6 As shown, specifically, the bearing rod 421 includes a first bearing rod 4211 and a second bearing rod 4212. There are two second bearing rods 4212, respectively located at both ends of the first bearing rod 4211. One end of the second bearing rod 4212 is threadedly connected to the first bearing rod 4211. By screwing the second bearing rod 4212, the length of the bearing rod 421 can be adjusted. The other end of the second bearing rod 4212 is provided with a bearing outer ring 4213. The bearing ball 422 is located inside the bearing outer ring 4213 and can rotate within it. The bearing ball 422 is provided with a through hole 4221. Connecting shafts 423 are respectively provided on the gripper 200 and the connecting plate 410. The connecting shafts 423 and the through hole 4221 enable the connecting plate 410 to connect with the bearing ball 422, and the gripper 400 to connect with the bearing ball 422. Preferably, the connecting shaft 423 is movably connected to the bearing ball 422 to improve the degree of freedom.

[0030] like Figure 1 , Figure 2As shown, the gripper 200 includes a straight section 210, an arc-shaped section 220, and a bent section 230 sequentially from the connecting end to the end. A guide wheel 600 is provided on the bent section 230. The guide wheel 600 is connected to the bent section 230 via a second rotating shaft 610. The guide wheel 600 can rotate around the second rotating shaft 610, and its surface protrudes beyond the very end of the bent section 230. The guide wheel 600 guides the basketball into the gripping space formed by the multiple grippers 200. Simultaneously, the guide wheel 600 converts the sliding friction between the basketball and the ends of the grippers 200 into rolling friction, thereby protecting the outer surface of the basketball. To guide the basketball to the center of the gripping space, the central radial plane of the guide wheel 600 is set to be coplanar with the central axis 110 of the mounting plate 100. To increase the friction between the guide wheel 600 and the basketball and prevent slippage, an annular groove 620 is also provided on the surface of the guide wheel 600. Preferably, the annular groove 620 is V-shaped or U-shaped, used to form a geometric interlock with the surface of the basketball, effectively resisting the lateral movement or rotation of the basketball, and enhancing the stability of the grip and the ability to prevent slippage. Figure 3 As shown, a protrusion 240 is formed at the connection between the arc segment 220 and the bent segment 230. The net distance D between the protrusion 240 and the central axis 110 is greater than the net distance d between the guide wheel 600 and the central axis 110 to prevent the basketball from being stuck by the protrusion 240. Preferably, Dd > 5mm. The side of the arc segment 220 facing the central axis 110 is set as an arc surface 221. The arc surfaces 221 on the multiple grippers 200 are distributed along the same hemisphere, forming an approximately spherical enclosing space. When the multiple grippers 200 are closed, these arc surfaces 221 can simultaneously and evenly wrap the basketball from multiple directions. Compared with a flat surface or sharp edges, this greatly increases the contact area between the grippers 200 and the basketball, making the gripping force evenly distributed. While protecting the surface of the basketball, it also makes the grip more stable. On the other hand, the geometric relationship between the curved surface 230 and the spherical surface provides a higher degree of restraint. During arm swings, throwing, and other actions, this design can effectively prevent the basketball from slipping or rotating slightly, making the action more precise. A flexible layer (not shown) is also provided on the curved surface 221, which protects the surface of the basketball and increases the friction between the gripper 200 and the basketball surface. The flexible layer can be made of materials such as rubber or silicone.

[0031] An elastic component 700 is provided between multiple grippers 200. The elastic component 700 connects the multiple grippers 200 to each other. The elastic component 700 is provided on the straight section 210 of the gripper 200 to avoid interfering with the entry of the basketball. The elastic component 700 can be a spring, torsion spring, or elastic rope, etc. The elastic rope can be a rubber band or an elastic latex rope, etc. There can be one elastic rope or multiple elastic ropes.

[0032] Example 2 This embodiment provides a ball-catching method implemented by the end-effector grasping mechanism for a basketball robot as described in Embodiment 1 above, including the following steps: S1, The basketball bounces vertically upwards; S2. Control the motor 300 to rotate forward, driving all grippers to open synchronously to form an opening, with the opening vertically downward and aligned with the basketball. The ratio of the diameter of the opening formed by all grippers 200 to the diameter of the target basketball is 0.8-0.95. When the grippers 200 are open, the elastic component 700 is in a stretched state. S3. The basketball contacts the guide wheel 600 and, driven by its rebound kinetic energy, overcomes the tension of the elastic component 700 and squeezes into the gripping space formed by multiple grippers 200. At the same time, it forces the grippers 200 to further open and stretch the elastic component 700. S4. When the basketball touches the buffer pad 500 on the connecting plate 410, the motor 300 reverses, causing the connecting plate 410 to rotate. This causes multiple grippers 200 to retract via the fisheye bearing 420, working together to stably clamp the basketball within the gripping space.

[0033] Example 3 This embodiment illustrates the usage of the end effector through a complete throwing and catching motion, such as... Figure 7 As shown, in use, the end-effector is located at the end of the basketball robot's robotic arm, and its throwing and catching process is as follows: S10, Preparatory stage: Multiple grippers 200 close to hold the ball stably, and the robotic arm 800 is in the initial position, θ0≈-30° (downward relative to the horizontal line). S20, during the acceleration and release phase, the robotic arm 800 rapidly accelerates upwards, while the gripper 200 opens at a specific angle to control the ball's speed and direction. The release angle θ is +15° to +20° (relative to the horizontal upward direction), designed to ensure the basketball is thrown with a predominantly vertical upward velocity component, minimizing horizontal deviation. The maximum angular velocity ω (max) is 8 to 12 rad / s (adjustable), controlled by a brushless motor and encoder to achieve high-speed, stable swinging. The angular acceleration α is segmented: high acceleration in the initial stage (approximately 80 rad / s²) followed by deceleration in the later stage, designed to avoid jitter and improve ball release stability. The ball release position is located in the middle to later stage of the robotic arm 800's upward phase (released when θ ≈ +10°), because at this point the tangential velocity direction is close to vertically upward, resulting in the most stable ball release direction. S30, during the basketball's flight phase, the basketball rises and falls along a parabolic trajectory, and the control target is to predict the rebound point and timing; S40, during the rebound waiting phase, the grippers 200 of the end gripping mechanism open to an opening slightly smaller than the diameter of the basketball, waiting for the basketball to fall and "welcome" the ball; S50, during the squeezing and gripping phase, the rebound kinetic energy of the basketball overcomes the tension of the elastic component 700 and squeezes into the gripping space formed by multiple grippers 200. Then, the connecting plate 410 rotates, and the multiple grippers 200 retract through the fisheye bearing 420 to firmly grip the basketball.

[0034] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the technical solution of the present invention, and are not intended to limit the specific implementation of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the claims of the present invention should be included within the protection scope of the claims of the present invention.

Claims

1. An end effector for a basketball robot, comprising a mounting plate and a plurality of grippers, the mounting plate having a central axis, the plurality of grippers being evenly arranged around the central axis; each gripper having a connecting end and an end end, the connecting end being rotatably connected to the mounting plate, and the end end being a free end; a motor is mounted on the mounting plate, and a connecting plate is mounted on the output shaft of the motor, characterized in that, Each gripper is connected to the connecting plate via a fisheye bearing, which includes a bearing rod and two bearing balls. The bearing balls are respectively located at both ends of the bearing rod and can rotate relative to the bearing rod. The gripper and the connecting plate are respectively connected to the bearing balls at both ends of the bearing rod.

2. The end effector for a basketball robot according to claim 1, characterized in that, Multiple grippers are interconnected by elastic components.

3. The end effector for a basketball robot according to claim 2, characterized in that, The fisheye bearing is connected to the connecting plate to form a connection point. The projection of the bearing rod of the fisheye bearing on the connecting plate has an included angle α between it and the tangent of the movement trajectory of the connection point. The gripping mechanism has a pre-receiving ball state in which the included angle α is 20-40 degrees.

4. The end effector for a basketball robot according to claim 3, characterized in that, In the ready-to-receive state, on the plane perpendicular to the connecting plate, the angle a1 between the projection of the bearing rod and the gripper is 60-80 degrees.

5. The end effector for a basketball robot according to claim 1, characterized in that, The length of the bearing rod of the fisheye bearing is adjustable.

6. The end effector for a basketball robot according to any one of claims 1-5, characterized in that, The gripper includes a straight section, an arc section, and a bent section from the connecting end to the end. The bent section bends away from the central axis relative to the arc section, and a rotatable guide wheel is provided on the bent section.

7. The end effector for a basketball robot according to claim 6, characterized in that, A protrusion is formed between the arc-shaped segment and the bent segment, and the net distance between the protrusion and the central axis is greater than the net distance between the guide wheel and the central axis.

8. The end effector for a basketball robot according to claim 6, characterized in that, The arc-shaped segment has an arc-shaped surface on the side facing the central axis, and the arc-shaped surfaces of the multiple grippers are distributed along the same hemisphere.

9. The end effector for a basketball robot according to claim 1, characterized in that, The connecting plate is provided with a buffer pad, and the side of the buffer pad facing the end of the gripper is set as an arc-shaped concave surface.

10. The end effector for a basketball robot according to claim 1, characterized in that, The gripper has 4-6 jaws.

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