End effector for basketball robot and ball catching method

Abstract

The invention relates to the field of robots, in particular to an end effector for a basketball robot and a ball catching method.The end effector comprises a mounting plate and a plurality of clamping jaws, the mounting plate is provided with a central axis, and the multiple clamping jaws are evenly 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 and connected with the multiple clamping jaws through a driving mechanism so as to drive all the clamping jaws to synchronously rotate around the connecting position. The multiple clamping jaws are connected with one another through elastic components. The multiple clamping jaws are connected through the elastic component, all the clamping jaws jointly hold the basketball evenly and stably under the action of restoring force of the elastic component, the clamping state does not depend on continuous electric power, even if the motor is powered off, the basketball can still be held reliably, and as long as the diameters of the basketballs are within a certain range, even if the diameters of the basketballs are different, the basketball can be held stably. The end effector can also achieve stable clamping.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of robots, and more particularly, to an end effector for a basketball robot and a ball catching method. BACKGROUND

[0002] In the field of basketball robot technology, the end effector is a key component to realize the core functions such as grabbing, holding and shooting the ball. Its performance directly determines the reliability and competitiveness of the robot in a fast and dynamic game environment. Especially when completing the key task of "catching the ball", the end effector needs to quickly, stably and robustly capture the basketball rebounding from the wall or the basket, which puts high requirements on the success rate of the gripper, the self-adaptive ability and the safety and reliability of the end effector.

[0003] At present, the common end effector of a basketball robot mostly adopts a multi-claw structure based on motor driving. Its typical working mode is: the control system determines the catching time according to visual or time sequence information, and instructs the motor to drive multiple claws to open synchronously to form an acceptance space larger than the diameter of the basketball. When the basketball enters the space, the control system again issues an instruction to drive the motor to make the claws close quickly to hold the basketball. However, this traditional mode of "first fully opening, then waiting, and finally active closing" has the following defects: first, it lacks an effective physical guiding mechanism, and has high requirements on the positioning of the robot and the trajectory accuracy of the basketball, and poor fault tolerance. The claws of the existing technology form a fixed and passive acceptance space after opening. When there is even a small deviation in the trajectory of the rebounding basketball or the final positioning of the robot, the edge of the basketball will collide with the end of the claw instead of smoothly guiding it in. Such a collision is likely to produce a moment that makes the basketball bounce off, resulting in a failed catch. Second, it lacks a power-off safety mechanism. The clamping force of the traditional end effector is completely derived from the continuous power supply of the motor, and once the power is cut off, the claws often cannot maintain the clamping state, resulting in the falling of the basketball. SUMMARY

[0004] The present application aims to overcome at least one of the above-mentioned defects of the prior art, and provides an end effector for a basketball robot to solve the problems of the existing end effector lacking an effective physical guiding mechanism, having high requirements on the positioning of the robot and the trajectory accuracy of the basketball, poor fault tolerance, and lacking a power-off safety mechanism.

[0005] The technical solution adopted by the present application is an end effector for a basketball robot, comprising a mounting plate and multiple claws, the mounting plate having a central axis, and the multiple claws being evenly arranged around the central axis; the claws have a connecting end and a free end, the connecting end being rotationally connected to the mounting plate, and the free end being a free end; a motor is arranged on the mounting plate, and the motor is connected to the multiple claws through a driving mechanism to drive all the claws to rotate synchronously around the connecting part; the multiple claws are connected to each other through elastic components.

[0006] The end effector is arranged at the end of the basketball robot mechanical arm. After the basketball robot controls the mechanical arm to throw the basketball, the motor drives the plurality of clamping jaws to rotate around the connection, so that the clamping jaws are opened to an opening slightly smaller than the diameter of the basketball. At this time, the clamping jaws maintain the opening state and wait for the basketball to rebound. When the basketball rebounds to the area of the end effector, the basketball, with its rebounding kinetic energy, overcomes the tension generated by the elastic component and is squeezed into the grabbing space formed by the plurality of clamping jaws. Finally, the clamping jaws are retracted, and all the clamping jaws cooperatively hold the basketball evenly and stably, completing a catching task. By arranging the elastic component to connect the plurality of clamping jaws, the end of the clamping jaw is always close to the surface of the basketball when the basketball enters the grabbing space formed by the plurality of clamping jaws, thereby playing a guiding role and achieving a high success rate of grabbing and excellent fault tolerance. Secondly, after the basketball is squeezed in, the restoring force of the elastic component causes the clamping jaws to remain retracted. Even if the motor is powered off in subsequent movements, the basketball can still be reliably held, providing a power-off protection function and improving reliability. In addition, the elastic component can effectively absorb the impact energy when the basketball contacts the clamping jaws, changing the collision into squeezing, greatly reducing the possibility of impact, vibration and jamming, making the grabbing process more smooth and smooth, and having a buffering protection effect.

[0007] The clamping jaw includes, in sequence from the connection end to the end, a straight section, an arc section and a bent section. The bent section is located at the end of the clamping jaw, and a rotatable guide wheel is arranged on the bent section. When the basketball contacts the guide wheel, the guide wheel rolls to adapt to the deviation, so that even if the basketball does not hit the center directly, the guide wheel can guide it into the preset grabbing space through rolling, thereby further improving the success rate and fault tolerance of dynamic catching and reducing the requirement for the accuracy of the rebounding trajectory of the basketball. In addition, when the clamping jaw moves relative to the surface of the basketball (especially during the guiding stage in the process of the basketball being squeezed in), the rolling of the guide wheel replaces the sliding of the end of the clamping jaw, so that the basketball can be more smoothly and labor-savingly squeezed into the opened clamping jaw space, while effectively avoiding scratching the surface of the basketball due to sliding friction. The bent section is bent outward relative to the arc section, i.e., away from the center axis. When the basketball squeezes the guide wheel, a torque is generated that is more conducive to the overall outward opening of the clamping jaw, thereby reducing the force required for the basketball to squeeze into the grabbing space, making the catching process smoother. The bent section is bent outward relative to the arc section to form a protruding part. To prevent the basketball from being stuck by the protruding part after being squeezed into the guide wheel, the net distance between the protruding part and the center axis is set to be greater than the net distance between the guide wheel and the center axis, i.e., the diameter of a first virtual circle formed by all the protruding parts is greater than the diameter of a second virtual circle formed by all the guide wheels when the clamping jaws are opened.

[0008] The arc-shaped section of the clamping jaw is arc-shaped on the side facing the central axis (defined as the inner side), and the arc-shaped surfaces of the plurality of clamping jaws are distributed along the same hemispherical surface. In this way, the plurality of arc-shaped surfaces can collectively form an approximately spherical containing space, and when the clamping jaws are closed, these arc-shaped surfaces can simultaneously and uniformly wrap the basketball from multiple directions. Compared to flat surfaces or edges, the contact area between the clamping jaws and the basketball is greatly increased, and the gripping force is evenly distributed, thereby making the gripping more stable while protecting the surface of the basketball. On the other hand, the geometric relationship between the arc-shaped surface and the spherical surface provides a higher degree of constraint, which can effectively prevent the basketball from moving or rotating slightly during arm swinging or throwing, making the movement more accurate.

[0009] Compared to three clamping jaws, four to six clamping jaws can more evenly distribute the gripping force on the surface of the basketball under the same total clamping force, effectively avoiding excessive local pressure caused by too few clamping jaws, thereby better protecting the air tightness and surface integrity of the basketball. On the other hand, when there are only three clamping jaws, the elastic component forms a straight line between each two clamping jaws when the clamping jaws are opened in preparation, making the preparation profile a triangle, and the effective capture diameter (i.e. the diameter of the inscribed circle) will be smaller, which may affect the normal entry of the basketball. When the number of clamping jaws increases to four to six, the preparation profile is closer to a complete circle, greatly eliminating the straight edge effect, and making the effective capture diameter of the preparation opening closer to its theoretical maximum. However, if the number of clamping jaws is greater than six, the structural complexity and cost will increase dramatically. In addition, more moving parts mean greater inertia and more internal friction, which will slow down the response of the system in dynamic catching scenarios that require rapid opening and closing. Therefore, the number of clamping jaws is set to four to six.

[0010] The driving mechanism includes a connecting plate and a plurality of fish-eye bearings. The connecting plate is arranged on the output shaft of the motor, and each clamping jaw is connected to the connecting plate through a fish-eye bearing. When the motor is working, the connecting plate rotates, thereby rotating the clamping jaws around their connections with the mounting plate through the fish-eye bearings, achieving synchronous opening and closing of the plurality of clamping jaws. The fish-eye bearings provide a spherical pair of movements that can swing arbitrarily within a certain cone angle, compensating for assembly errors and avoiding jamming, abnormal noise, and additional wear caused by over-constraint, ensuring smooth driving. A buffer pad is provided on the connecting plate, which can limit and buffer the rigid collision between the basketball and the connecting plate. When the clamping jaws are upward, the buffer pad acts as a support. The side of the buffer pad facing the end of the clamping jaw is arc-shaped and concave, which can limit the movement of the basketball and make the clamping more stable, and improve the accuracy of arm swinging or throwing.

[0011] A method of catching a basketball implemented by the end effector of the basketball robot according to any one of claims 2-7, comprising the following steps: S1, the basketball bounces vertically upward; S2, control the motor to drive all the clamping jaws to open synchronously to form an opening, the opening is vertically downward aligned with the basketball, wherein the ratio of the diameter of the opening formed by the plurality of clamping jaws to the diameter of the target basketball is 0.8-0.95; S3, the basketball contacts the guide wheel and, driven by the rebounding kinetic energy, overcomes the tension of the elastic component, and is squeezed into the grabbing space formed by the plurality of clamping jaws, while forcing the clamping jaws to open further and stretch the elastic component; S4, the plurality of clamping jaws contracts to stably clamp the basketball in the grabbing space.

[0012] In the traditional ball catching method, the opening of the clamping jaw is larger than the diameter of the basketball, and at the moment when the basketball enters the grabbing space, the clamping jaw contracts to clamp the basketball in the grabbing space. This ball catching method requires high accuracy of positioning and trajectory of the basketball robot and has poor fault tolerance. Unlike the traditional ball catching method, in the ball catching method of the present application, the ratio of the diameter of the opening of the clamping jaw to the diameter of the basketball is 0.8-0.95, and the diameter of the opening is slightly smaller than the diameter of the basketball. The basketball overcomes the tension of the elastic component and is squeezed into the grabbing space. The cooperation of the elastic component and the guide wheel can make the guide wheel closely contact the surface of the basketball, thereby effectively guiding the basketball to the center of the plurality of clamping jaws and improving the success rate of grabbing. In addition, after the basketball is squeezed into the grabbing space, the restoring force of the elastic component will make the clamping jaw contract, so that the clamping jaw can remain in the clamping state even if the motor is powered off. By setting the ratio of the diameter of the opening of the clamping jaw to the diameter of the basketball to 0.8-0.95, the basketball can be smoothly squeezed into the grabbing space, and the clamping jaw can effectively clamp the basketball after it is squeezed in to prevent it from falling. If the ratio is less than 0.8, i.e. the opening is too small, the basketball may be bounced back after contacting the guide wheel and cannot be squeezed into the grabbing space. If the ratio is greater than 0.95, i.e. the opening is too large, the contact between the basketball and the end of the clamping jaw will change from squeezing to the traditional direct collision. In addition, when the diameter of the opening of the clamping jaw is constant, the end effector is still applicable to different diameters of the basketball as long as the diameter of the opening and the diameter of the basketball are within the range of 0.8-0.95.

[0013] In step S2, when the clamping jaw is opened, the elastic component is in a stretched state and has a certain restoring force, which ensures that the basketball can be pushed towards the center at the moment of contacting the clamping jaw, thereby playing a role in forced guidance. In addition, this initial stretched state is the basis for generating sufficient clamping force, which ensures that the elastic component still has restoring force to promote the clamping jaw to clamp the basketball even if the motor is powered off after the basketball is squeezed into the grabbing space.

[0014] In step S4, when the basketball contacts the cushion on the connecting plate, the connecting plate rotates and the plurality of claws are retracted by the fish-eye bearing. This ensures that the final clamping action of the claws occurs at the moment when the basketball has moved to the deepest part of the gripping space, in the most ideal clamping position.

[0015] Compared with the prior art, the present application has the advantages that: the plurality of clamping jaws are connected to each other by the elastic component, so that the end of the clamping jaw is always close to the surface of the basketball during the process of the basketball being squeezed into the grabbing space, thereby playing a guiding role and improving the success rate of grabbing, and having excellent fault tolerance. When the basketball is squeezed into the grabbing space, the restoring force of the elastic component causes the clamping jaw to remain in a contracted state, so that the basketball can be reliably held even if the motor is powered off in subsequent actions, thereby providing a power-off protection function. The elastic component can also effectively absorb the impact energy when the basketball contacts the clamping jaw, thereby playing a buffering and protecting role. The end of the clamping jaw is provided with a rotatable guide wheel, so that the sliding friction between the basketball and the end of the clamping jaw is changed into rolling friction between the basketball and the guide wheel, so that the basketball can be more smoothly and labor-savingly squeezed into the grabbing space, and the surface of the basketball is effectively prevented from being scratched due to sliding friction. The guide wheel can further improve the success rate and fault tolerance of dynamic ball catching by rolling in response to deviation, thereby reducing the requirement for the accuracy of the rebound trajectory of the basketball, so that even if the basketball does not hit the center directly, the guide wheel can guide the basketball into the preset grabbing space through rolling. The bent part is bent outward, so that a torque that is more conducive to the overall outward opening of the clamping jaw is generated when the basketball squeezes the guide wheel, thereby reducing the force required for the basketball to be squeezed into the grabbing space, and making the ball catching process smoother. The net distance between the protruding part and the center axis is greater than the net distance between the guide wheel and the center axis, so that the basketball can be prevented from being stuck by the protruding part during the squeezing process. The inner side of the arc-shaped section is provided with an arc surface, and the arc surfaces of the plurality of clamping jaws are distributed along the same hemispherical surface, so that the plurality of arc surfaces collectively form an approximately spherical containing space, and when the clamping jaws are closed, the basketball can be uniformly wrapped, the contact area between the clamping jaw and the basketball is increased, and the grabbing force is uniformly distributed. At the same time, the arc surface and the surface of the basketball provide a higher degree of constraint, so that the basketball is effectively prevented from moving or rotating slightly during actions such as arm swinging and throwing, thereby making the action more accurate. The driving mechanism includes a connecting plate arranged on the output shaft of the motor, and a plurality of fish-eye bearings for connecting the clamping jaw and the connecting plate, so that when the motor drives the connecting plate to rotate, the plurality of clamping jaws can be synchronously driven through the fish-eye bearings, thereby realizing the opening and closing of the plurality of clamping jaws. The connecting plate is provided with a buffer pad, so that the buffer pad can play a buffering and supporting role, and the side of the buffer pad facing the end of the clamping jaw is provided with an arc-shaped concave surface, so that the buffer pad can play a certain limiting role. In the ball catching method, the ratio of the opening diameter of the clamping jaw when opened to the diameter of the basketball is 0.8-0.95, so that the basketball can be conveniently and smoothly squeezed into the grabbing space, and after the basketball is squeezed into the grabbing space, the clamping jaw can effectively hold the basketball, thereby avoiding the situation that the basketball cannot be squeezed into the grabbing space due to the opening of the clamping jaw being too small, and the situation that the basketball may fall out of the grabbing space after being squeezed into the grabbing space due to the opening of the clamping jaw being too large. When the clamping jaw is opened, the elastic component is in a stretched state and has a certain restoring force, so that after the basketball is squeezed into the grabbing space, the elastic component can cause the plurality of clamping jaws to be in a contracted state, thereby stably holding the basketball.When the basketball contacts the cushioning pad, the connecting plate rotates, causing all the grippers to retract via the fisheye bearing, thus achieving clamping. This ensures that the basketball moves to the deepest part of the gripping space and is in the most ideal clamping position during clamping. 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 structural diagram of the present invention mounted on a robotic arm.

[0020] 100. Mounting plate; 110. Central axis; 120. First rotating shaft; 200. Gripper; 210. Straight section; 220. Arc section; 221. Arc surface; 230. Bending section; 240. Protrusion; 300. Motor; 400. Drive mechanism; 410. Connecting plate; 420. Fisheye bearing; 500. Buffer pad; 510. Arc concave surface; 600. Guide wheel; 610. Second rotating shaft; 620. Annular groove; 700. Elastic component; 800. Robotic arm. Detailed Implementation

[0021] 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.

[0022] 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.

[0023] Example 1 like Figure 1 , Figure 2As shown, an end effector for a basketball robot comprises a mounting plate 100 having a central axis 110 and a plurality of grippers 200 evenly arranged around the central axis 110; the gripper 200 has a connecting end and a terminal end, the connecting end is connected with the mounting plate 100 through a first rotating shaft 120, the gripper 200 can rotate around the first rotating shaft 120, and the terminal end of the gripper 200 is a free end. A plurality of grippers 200 form a gripping space. Preferably, the gripper 200 has 4-6.

[0024] The mounting plate 100 is provided with a motor 300, 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 with the plurality of grippers 200 through a driving mechanism 400, the driving mechanism 400 comprises a connecting plate 410 and a plurality of fish-eye bearings 420, the connecting plate 410 is fixed on the output shaft of the motor 300, one end of the fish-eye bearing 420 is connected with the connecting plate 410, and the other end is connected with the gripper 200. When the motor 300 works, the connecting plate 410 rotates, thereby synchronously rotating the plurality of grippers 200 around the first rotating shaft 120 through the fish-eye bearings 420, so as to realize opening and closing. The connecting plate 410 is provided with a buffer pad 500, the buffer pad 500 is a horn-shaped, and the side facing the terminal end of the gripper 200 is provided with an arc-shaped concave surface 510. The buffer pad 500 has the functions of limiting, buffering and supporting, and the material thereof can be silica gel, rubber, polyurethane and the like. A sensor (not shown) can be arranged on the buffer pad 500, when the basketball touches the buffer pad 500, the motor 300 works, the output shaft thereof reverses, drives the connecting plate 410 to reverse, and closes the gripper 200 through the fish-eye bearing 420.

[0025] As Figure 1 , Figure 2As shown, the clamping jaw 200 comprises, in sequence from the connecting end to the terminal end, a flat section 210, an arc section 220 and a bent section 230, the bent section 230 is provided with a guide wheel 600, the guide wheel 600 is connected with the bent section 230 through a second rotating shaft 610, the guide wheel 600 can rotate around the second rotating shaft 610, and the wheel surface of the guide wheel 600 protrudes from the terminal end of the bent section 230. The guide wheel 600 is used to guide the basketball into the grabbing space formed by the plurality of clamping jaws 200, at the same time, the setting of the guide wheel 600 can convert the sliding friction between the basketball and the terminal end of the clamping jaw 200 into rolling friction, thereby protecting the outer surface of the basketball. In order to guide the basketball to the center of the grabbing space, the central radial plane of the guide wheel 600 is arranged to be coplanar with the central axis 110 of the mounting plate 100. In order to increase the friction between the guide wheel 600 and the basketball and prevent slipping, the wheel surface of the guide wheel 600 is further provided with an annular groove 620, preferably, the annular groove 620 is V-shaped or U-shaped in shape, which is used to form geometric interlocking with the spherical surface of the basketball, effectively resisting the lateral movement or rotation of the basketball, enhancing the stability and anti-dropping ability of grabbing. As shown in the figure, Figure 3 As shown, a protrusion 240 is formed at the connection between the arc section 220 and the bent section 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, so as to prevent the basketball from being stuck by the protrusion 240. Preferably, D-d>5mm. The side of the arc section 220 towards the central axis 110 is provided with an arc surface 221, the arc surfaces 221 on the plurality of clamping jaws 200 are distributed along the same hemispherical surface, and together constitute an approximately spherical containing space. When the plurality of clamping jaws 200 are closed, these arc surfaces 221 can simultaneously and uniformly wrap the basketball from multiple directions, greatly increasing the contact area between the clamping jaw 200 and the basketball compared to flat surfaces or edges, so that the grabbing force is uniformly distributed, protecting the surface of the basketball while making the grabbing more stable. On the other hand, the geometric relationship between the arc surface 230 and the spherical surface provides higher restraint, which can effectively prevent the slight movement or rotation of the basketball during arm swinging, throwing and other actions, making the action more accurate. The arc surface 221 is further provided with a flexible layer (not shown), which can protect the surface of the basketball and increase the friction between the clamping jaw 200 and the surface of the basketball. The flexible layer can be made of rubber, silicone or other materials.

[0026] A plurality of elastic components 700 are arranged between the plurality of clamping jaws 200, the elastic components 700 connect the plurality of clamping jaws 200 to each other, the elastic components 700 are arranged on the flat section 210 of the clamping jaw 200 to avoid interfering with the entry of the basketball, the elastic components 700 can be springs, torsional springs or elastic ropes, the elastic rope can be a rubber band or a latex rope with elasticity, and the elastic rope can be one or multiple.

[0027] Embodiment 2 The embodiment provides a ball catching method realized by the end effector of the basketball robot in Embodiment 1, and the method comprises the following steps: S1, the basketball rebounds vertically upward; S2, the motor 300 is controlled to rotate in the forward direction, all the clamping jaws are driven to open synchronously to form an opening, and the opening is vertically downward aligned with the basketball, wherein the ratio of the diameter of the opening formed by the opening of all the clamping jaws 200 to the diameter of the target basketball is 0.8-0.95; when the clamping jaws 200 open, the elastic component 700 is in a stretched state; S3, the basketball contacts the guide wheel 600, and under the driving of the rebounding kinetic energy, the basketball squeezes into the grabbing space formed by the plurality of clamping jaws 200, and at the same time, the clamping jaws 200 are forced to open further and the elastic component 700 is stretched; S4, when the basketball touches the buffer pad 500 on the connecting plate 410, the motor 300 reverses, the connecting plate 410 rotates, the plurality of clamping jaws 200 are retracted through the fisheye bearing 420, and the basketball is stably clamped in the grabbing space.

[0028] Embodiment 3 The embodiment introduces the use of the end effector through a complete throwing and catching action, as shown in the following table: Figure 4 When in use, the end effector is arranged at the end of the mechanical arm of the basketball robot, and the throwing and catching process is as follows: S10, a preparation stage, the plurality of clamping jaws 200 are closed to stably hold the ball, and the mechanical arm 800 is located at an initial position, θ0≈-30° (downward relative to the horizontal line); S20, an acceleration and throwing stage, the mechanical arm 800 is accelerated upward quickly, the clamping jaws 200 are opened at a specific angle to control the throwing speed and direction; the throwing angle θ is +15°~+20° (upward relative to the horizontal line), and the purpose is to ensure that the basketball is thrown with a vertical upward speed component as the main component and the horizontal deviation is reduced; the maximum angular velocity ω(max) is 8~12 rad / s (adjustable), which is realized by controlling the brushless motor and the encoder, so that the high-speed stable throwing is realized; the angular acceleration α is controlled in sections: the front section is high acceleration (about 80 rad / s²), and the rear section is deceleration, so as to avoid shaking and improve the throwing stability; the ball is released at the middle and rear section of the rising section of the mechanical arm 800 (when θ ≈ +10°), because at this time, the tangential velocity direction is close to vertical upward, and the throwing direction is most stable; S30, a basketball flying stage, the basketball rises and falls along a parabolic trajectory, and the control target is to predict the rebounding point and timing; S40, rebound waiting stage, the gripper 200 of the end effector is opened to an opening slightly smaller than the diameter of the basketball, and waits for the basketball to fall and "welcome" the ball; S50, extrusion gripping stage, the rebound kinetic energy of the basketball overcomes the tension of the elastic component 700, and is extruded into the gripping space formed by the plurality of grippers 200, and then the connecting plate 410 rotates to make the plurality of grippers 200 shrink through the fisheye bearing 420 to stably clamp the basketball.

[0029] Obviously, the above embodiments of the present application are only examples for clearly illustrating the technical solutions of the present application, and are not intended to limit the specific embodiments of the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the claims of the present application should be included in the protection scope of the claims of the present application.

Claims

1. A terminal actuator 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; the grippers having a connecting end and a terminal end, the connecting end being rotatably connected with the mounting plate, and the terminal end being a free end; a motor being arranged on the mounting plate, the motor being connected with the plurality of grippers through a driving mechanism to drive all the grippers to synchronously rotate around the connecting end; characterized in that, The plurality of clamping claws are connected to each other by elastic components.

2. The end effector for a basketball robot of claim 1, wherein, The clamping claw comprises, from the connecting end to the terminal end, a straight section, an arc section and a bent section in sequence, the bent section is bent away from the central axis relative to the arc section, and a rotatable guide wheel is arranged on the bent section.

3. The end effector for a basketball robot of claim 2, wherein, A protrusion is formed between the arc section and the bent section, 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.

4. The end effector for a basketball robot of claim 2, wherein, The side of the arc section facing the central axis is an arc surface, and the arc surfaces of the plurality of clamping claws are distributed along the same hemisphere.

5. The end effector for a basketball robot according to any one of claims 1-4, wherein, The clamping claw has 4-6 clamping claws.

6. The end effector for a basketball robot according to any one of claims 1-4, wherein, The driving mechanism comprises a connecting plate and a plurality of fish-eye bearings, the connecting plate is fixed to the output shaft of the motor, and each clamping claw is connected to the connecting plate through a fish-eye bearing.

7. The end effector for a basketball robot of claim 6, wherein, A buffer pad is arranged on the connecting plate, and the side of the buffer pad facing the terminal end of the clamping claw is arranged as an arc concave surface.

8. A method of catching a ball implemented by the end effector of the basketball robot of any one of claims 2-7, characterized in that, The method comprises the following steps: S1, the basketball bounces vertically upward; S2, the motor is controlled to drive all the clamping claws to open synchronously to form an opening, the opening is vertically downward aligned with the basketball, wherein the ratio of the diameter of the opening formed by the plurality of clamping claws to the diameter of the target basketball is 0.8-0.95; S3, the basketball contacts the guide wheel and, driven by the rebounding kinetic energy, overcomes the tension of the elastic component and is squeezed into the grabbing space formed by the plurality of clamping claws, while forcing the clamping claws to open further and stretch the elastic component; S4, the plurality of clamping claws are retracted to stably clamp the basketball in the grabbing space.

9. The method of catching a ball of claim 8, wherein, In step S2, when all the clamping claws open synchronously to form an opening, the elastic component is in a stretched state.

10. The method of catching a ball of claim 8, wherein, In step S4, when the basketball contacts the buffer pad on the connecting plate, the connecting plate rotates and retracts the plurality of clamping claws through the fish-eye bearings.

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