Hybrid platform based on 3SPS-PU-3PRR, working method and application

Abstract

The invention relates to a hybrid platform based on 3SPS-PU-3PRR, a working method and application, and belongs to the technical field of manipulators. Comprising a fixed platform, a relay platform and a movable platform, three PRR branch chains are connected between the fixed platform and the relay platform, three SPS branch chains and a PU branch chain are connected between the relay platform and the movable platform, three sets of lead screws are arranged on the fixed platform, the lead screws drive the relay platform to move relative to the fixed platform when doing reciprocating rectilinear motion, and the lead screws drive the relay platform to move relative to the fixed platform when doing reciprocating rectilinear motion when doing reciprocating rectilinear motion. And when the PU branch chains act, the distance between the movable platform and the relay platform is limited, and more reliable structural support and motion stability are provided. The movable platform can perform limited six-degree-of-freedom movement relative to the fixed platform, and the relay platform can perform limited planar movement and rotation relative to the fixed platform. Performance balance is achieved, and the mechanical arm has the advantages of being large in rigidity, stable in structure, high in precision, small in error and large in working space.

Description

Technical Field

[0001] The present invention relates to a hybrid platform based on 3SPS-PU-3PRR, its working method and application, and belongs to the technical field of manipulators. Background Art

[0002] As more and more platform devices begin to develop towards intelligence and automation, considering safety, accuracy, etc., in some special application scenarios, it is required that the platform structure moves finely and gently within a small range, and has high requirements for the accuracy, reliability, stiffness and working space of the platform mechanism. Existing platforms using series mechanisms or parallel mechanisms can only meet the requirements of large-amplitude and large-movement. To solve such problems, the present invention designs a hybrid platform based on 3SPS-PU-3PRR, and adopts a combination of a parallel robot and a platform to achieve fine movement of the platform. Utilizing the characteristics of high stability, low error, high stiffness and high dynamic performance of the parallel robot to ensure natural movement and stable structure of the platform. Combining the serial robot with the platform increases the degrees of freedom and working space of the mechanism, and ensures that the mechanism will not appear in a singular configuration. Combining the serial and parallel robots not only retains the advantages of the parallel robot but also adds the characteristics of the serial robot. Therefore, it is very necessary to propose a hybrid platform based on 3SPS-PU-3PRR. Summary of the Invention

[0003] Aiming at the deficiencies of the prior art, the present invention provides a hybrid platform based on 3SPS-PU-3PRR and its application, whose actions are directly controlled by lead screws and electric cylinders, with large load and high operating efficiency.

[0004] The technical solution of the present invention is as follows:

[0005] A hybrid platform based on 3SPS-PU-3PRR includes a fixed platform, a relay platform and a moving platform. There are three PRR chains connected between the fixed platform and the relay platform, and three SPS chains and one PU chain connected between the relay platform and the moving platform;

[0006] There are three groups of lead screws on the fixed platform. Each lead screw includes a guide rail, and a slider is arranged through the guide rail. One end of the guide rail is connected with a motor, and the guide rail is threadedly connected with the slider; the motor drives the guide rail to rotate, and drives the slider to move horizontally through the thread;

[0007] The PRR chain includes a first rotating pair, a moving pair rod and a second rotating pair connected in sequence. The first rotating pair is connected with the slider, and the second rotating pair is connected with the relay platform; the PRR chain forms a first driving device. When the slider makes a reciprocating linear motion along the guide rail, it drives the relay platform to move relative to the fixed platform;

[0008] The SPS branch chain includes an upper spherical pair, an SPS prismatic pair, and a lower spherical pair connected in sequence. The upper spherical pair is connected to the moving platform, and the lower spherical pair is connected to the relay platform; the SPS branch chain forms the second driving device; when the SPS prismatic pair acts, it drives the moving platform to move relative to the relay platform;

[0009] The PU branch chain includes a PU prismatic pair and a universal joint connected in sequence. One end of the PU prismatic pair is fixedly connected to the moving platform, the other end of the PU prismatic pair is connected to the universal joint, and the universal joint is connected to the relay platform. The PU branch chain forms the third driving device. When the PU prismatic pair acts, it restricts the distance between the moving platform and the relay platform, providing more reliable structural support and motion stability.

[0010] The moving platform can perform six-degree-of-freedom movement with restrictions relative to the fixed platform, and the relay platform can perform planar movement and rotation with restrictions relative to the fixed platform.

[0011] Preferably, the fixed platform and the relay platform are in the same plane, and the moving direction of the second moving platform is restricted to the plane where the first moving platform is located; or the planes where they are located are parallel to each other.

[0012] Preferably, the first revolute pair is a U-shaped plate, and two plates at the opening of the U-shaped plate are hinged to the slider; the second revolute pair is a U-shaped plate, and two plates at the opening of the U-shaped plate are hinged to the relay platform.

[0013] Preferably, the projection of the fixed platform is a hexagon, the projection of the relay platform is a triangle, and the projection of the moving platform is a triangle; the three groups of lead screws on the fixed platform are spaced apart on six sides, the three PRR branch chains are respectively connected to three sides of the relay platform, both ends of the three SPS branch chains are respectively connected to the acute angles of the relay platform and the moving platform, and both ends of the PU branch chain are connected to the centers of the relay platform and the moving platform.

[0014] Further preferably, the area of the triangle of the moving platform is smaller than the area of the triangle of the relay platform. In this way, the three SPS branch chains are not placed vertically up and down, but are inclined at a certain angle to the vertical direction.

[0015] Preferably, the PU prismatic pair is vertically fixed to the moving platform.

[0016] Preferably, both the SPS prismatic pair and the PU prismatic pair are cylinders controlled by motors. The cylinder includes a cylinder rod and a slideway, and the cylinder rod expands and contracts in the slideway. The motor controls the expansion and contraction of the cylinder, thereby realizing the change of the distance on the line where the prismatic pair is located.

[0017] A working method of a hybrid platform based on 3SPS-PU-3PRR includes the following steps:

[0018] When the hybrid platform drive device is actively driven, when the motors connected to the three sets of screws on the fixed platform are working, the first rotating pair of the PRR branch chain slides on the guide rail of the ball screw, and the relative position of the first rotating pair and the rotating pair rod changes. The rotating pair rod swings with the moving direction of the first rotating pair. Due to the existence of two rotating pairs, within a certain range of movement of the first rotating pair, only the rotating pair rod swings without driving the relay platform to move relative to the fixed platform; when the first rotating pair moves beyond a certain range, the relay platform moves relative to the fixed platform. At this time, the SPS branch chain moves with the relay platform, and the SPS moving pair in the SPS branch chain performs telescopic movement. It is not placed vertically but at a certain angle and the existence of lower and upper ball pairs allows the relay platform to make larger movements while the SPS moving pair in the SPS branch chain only makes smaller telescopic changes, ensuring that the moving platform only swings slightly to one side without violent shaking, ensuring comfort and safety; at the same time, the PU moving pair of the PU branch chain telescopes and slides in the cylinder slide of the electric cylinder as the relay platform, ensuring that the moving platform does not move up and down violently. The bottom of the PU branch chain is connected to the relay platform through a universal joint, ensuring that the PU branch chain can swing to a certain extent without causing the moving platform to rotate violently, but only makes a slight swing.

[0019] When the dynamic platform moves and causes the hybrid platform to be passively driven, and when the dynamic platform moves up and down due to the weight change above the dynamic platform, the PU moving pair of the PU branch chain performs telescopic-stretching motion along the cylinder slide in the cylinder, weakening the downward movement trend of the dynamic platform. The SPS moving pair of the SPS branch chain performs telescopic-stretching motion along the cylinder slide in the cylinder. At the same time, the relay platform rotates with the movement of the moving pair in the SPS branch chain. The PRR branch moves with the movement of the relay platform, and the rotating pair rod swings to drive the slider to perform reciprocating linear motion along the guide rail. Through successive motion and force transmission, the movement trend of the dynamic platform is weakened, the rigidity and stability of the hybrid platform are increased, and the safety and comfort of the hybrid platform are ensured.

[0020] When the change of the weight and centroid above the moving platform causes the moving platform to swing up and down, the PU moving pairs of the PU branches also perform telescopic movements, and the SPS moving pairs of the SPS branches also perform telescopic movements. For the SPS branches closer to the swinging direction of the moving platform, the SPS moving pairs perform telescopic movements, and the moving pairs in the remaining SPS branches perform stretching movements or remain unchanged. The relay platform rotates with the movement of the SPS branches, and the rotating pair rod and the slider perform corresponding movements, gradually weakening the movement of the moving platform to ensure the safety and comfort of the hybrid platform. When the swing amount of the moving platform is too large, due to the existence of universal joints in the PU branches, the PU branches will generate a certain swing, causing the PU branches to change from a vertical state to an inclined state, but the PU branches are always perpendicular to the moving platform and have a certain angle with the relay platform; for the SPS branches, the SPS moving pairs in the SPS branches closer to the swinging direction perform telescopic movements, and the remaining SPS branches perform stretching movements. Due to the existence of the lower spherical pair and the upper spherical pair, the SPS branches tilt by a certain amount, increasing the allowable descent amount of the third moving platform. However, limited by the PU branches, at this time, the second moving platform not only rotates but also translates relative to the fixed platform; at the same time, the PRR moves with the movement of the relay platform.

[0021] An application of a hybrid platform based on 3SPS-PU-3PRR. Place an object that needs to be finely adjusted, such as a crib, on the moving platform. At the same time, set up a control panel, and the control panel is connected to all motors. When active rocking is required, the start sequence of the motors is set by the control panel.

[0022] The beneficial effects of the present invention are as follows:

[0023] This application can play a huge advantage in scenarios that require precise movement. For example, the intelligent crib technology based on the hybrid platform integrates the cross-disciplinary innovation of precise motion control and infant care. It can combine lightweight composite materials and a high-precision brushless motor drive system, break through the limitations of traditional single-axis cribs, and accurately simulate the three-dimensional biomechanical characteristics of the mother's body through six-degree-of-freedom motion; the series-parallel mechanism combines the advantages of both parallel and series mechanisms, makes up for the defects in the application fields of individual mechanisms, realizes the performance balance between serial robots and parallel robots, and makes this hybrid platform have the characteristics of high stiffness, stable structure, high precision, small error, and large working space. Description of the Drawings

[0024] Figure 1 Overall structure diagram of the present invention;

[0025] Figure 2 Schematic diagram of the PRR branch;

[0026] Figure 3 Schematic diagram of the SPS branch;

[0027] Figure 4Schematic diagram of the PU branch chain;

[0028] Wherein: 1. Fixed platform, 2. Slide block, 3. Guide rail, 4. Motor, 5. First revolute pair, 6. Revolute pair rod, 7. Relay platform, 8. Lower spherical pair, 9. Cylinder, 10. SPS prismatic pair, 11. Upper spherical pair, 12. Moving platform, 13. PU prismatic pair, 14. Universal joint, 15. Second revolute pair. Detailed implementation manners

[0029] The present invention will be further described below by way of embodiments in conjunction with the accompanying drawings, but is not limited thereto.

[0030] Embodiment 1:

[0031] A hybrid platform based on 3SPS-PU-3PRR, as Figures 1-4 shown, includes a fixed platform 1, a relay platform 7, and a moving platform 12. Three PRR branch chains are connected between the fixed platform and the relay platform, and three SPS branch chains and one PU branch chain are connected between the relay platform and the moving platform.

[0032] Three sets of lead screws are provided on the fixed platform. Each lead screw includes a guide rail 3. A slide block 2 is penetrated through the guide rail. One end of the guide rail is connected with a motor 4. The guide rail is in threaded connection with the slide block; the motor drives the guide rail to rotate, and drives the slide block to move horizontally through the thread. The fixed platform and the relay platform are in the same plane, and the moving direction of the second moving platform is restricted in the plane where the first moving platform is located.

[0033] The PRR branch chain includes a first revolute pair 5, a revolute pair rod 6, and a second revolute pair 15 connected in sequence. The first revolute pair 5 is connected with the slide block 2, and the second revolute pair 15 is connected with the relay platform 7; the PRR branch chain forms a first driving device. When the slide block makes a reciprocating linear motion along the guide rail, it drives the relay platform to move relative to the fixed platform. The first revolute pair is a U-shaped plate, and two plates at the opening of the U-shaped plate are hinged with the slide block; the second revolute pair is a U-shaped plate, and two plates at the opening of the U-shaped plate are hinged with the relay platform.

[0034] The SPS branch chain includes an upper spherical pair 11, an SPS prismatic pair 10, and a lower spherical pair 8 connected in sequence. The upper spherical pair 11 is connected with the moving platform 12, and the lower spherical pair 8 is connected with the relay platform 7; the SPS branch chain forms a second driving device; when the SPS prismatic pair acts, it drives the moving platform to move relative to the relay platform.

[0035] The PU branch chain includes a PU prismatic pair 13 and a universal joint 14 connected in sequence. One end of the PU prismatic pair 13 is fixedly connected to the moving platform 12, the other end of the PU prismatic pair is connected with the universal joint 14, and the universal joint 14 is connected with the relay platform 7. The PU branch chain forms a third driving device. When the PU prismatic pair acts, it restricts the distance between the moving platform and the relay platform, providing more reliable structural support and motion stability.

[0036] Both the SPS prismatic pair and the PU prismatic pair are cylinders 9 controlled by motors. The cylinder includes a cylinder rod and a slideway, and the cylinder rod expands and contracts within the slideway. The motor controls the expansion and contraction of the cylinder, thereby realizing the change of the distance on the line where the prismatic pair is located.

[0037] The moving platform can perform six-degree-of-freedom movement with restrictions relative to the fixed platform, and the relay platform can perform planar movement and rotation with restrictions relative to the fixed platform.

[0038] Embodiment 2:

[0039] A hybrid platform based on 3SPS-PU-3PRR has a structure as described in Embodiment 1. The difference is that the projection of the fixed platform is a hexagon, the projection of the relay platform is a triangle, and the projection of the moving platform is a triangle; the three groups of lead screws on the fixed platform are spaced apart on six sides, and the three PRR chains are respectively connected to three sides of the relay platform. The two ends of the three SPS chains are respectively connected to the acute angles of the relay platform and the moving platform, and the two ends of the PU chain are connected to the centers of the relay platform and the moving platform. The triangular area of the moving platform is smaller than the triangular area of the relay platform. In this way, the three SPS chains are not placed vertically up and down, but are inclined at a certain angle with respect to the vertical direction. The PU prismatic pair is fixedly perpendicular to the moving platform.

[0040] Embodiment 3:

[0041] A working method of using the hybrid platform based on 3SPS-PU-3PRR described in Embodiment 2 includes the following steps:

[0042] When the hybrid platform driving device is used for active driving, when the motors connected to the three sets of lead screws on the fixed platform are working, the first rotating pair of the PRR branch slides on the guide rail of the ball screw, and the relative position between the first rotating pair and the rotating pair rod changes. The rotating pair rod swings along with the moving direction of the first rotating pair. Due to the existence of the two rotating pairs, within a certain range of movement of the first rotating pair, only the rotating pair rod swings without driving the relay platform to move relative to the fixed platform. When the movement of the first rotating pair exceeds a certain range, the relay platform moves relative to the fixed platform. At this time, with the movement of the relay platform, the SPS moving pair in the SPS branch makes a telescopic movement. Since the SPS branch is not vertically placed but has a certain angle and the existence of the lower and upper spherical pairs, it allows the relay platform to make a relatively large movement while the SPS moving pair in the SPS branch only makes a relatively small telescopic change, ensuring that the moving platform only makes a slight swing to one side without violent shaking, thus ensuring comfort and safety. At the same time, the PU moving pair of the PU branch makes a telescopic-stretching sliding in the cylinder slide of the electric cylinder along with the relay platform, ensuring that the moving platform does not make violent up and down movements. The bottom of the PU branch is connected to the relay platform through a universal joint, ensuring that the PU branch can make a certain swing without causing the moving platform to make violent rotation, but only make a slight swing.

[0043] When the movement of the moving platform causes the hybrid platform to be driven passively, when the moving platform makes a vertical translation up and down due to weight changes above the moving platform, the PU moving pair of the PU branch makes a telescopic-stretching movement along the cylinder slide in the cylinder, weakening the downward movement trend of the moving platform. The SPS moving pair of the SPS branch makes a telescopic-stretching movement along the cylinder slide in the cylinder. At the same time, the relay platform makes a rotational movement with the movement of the moving pair in the SPS branch. With the movement of the relay platform, the rotating pair rod swings to drive the slider to make a reciprocating linear movement along the guide rail. Through successive movement and force transmission, the movement trend of the moving platform is weakened, increasing the stiffness and stability of the hybrid platform and ensuring the safety and comfort of the hybrid platform.

[0044] When the change in the weight center of gravity above the moving platform causes the moving platform to swing up and down, the PU moving pairs of the PU chain also perform telescopic movements, and the SPS moving pairs of the SPS chain also perform telescopic movements. For the SPS chain closer to the swinging direction of the moving platform, the SPS moving pair performs telescopic movement, and the moving pairs in the remaining SPS chains perform stretching movements or remain unchanged. The relay platform rotates with the movement of the SPS chain, and the rotating link and slider perform corresponding movements, gradually weakening the movement of the moving platform to ensure the safety and comfort of the hybrid platform. When the swing amount of the moving platform is too large, due to the presence of universal joints in the PU chain, the PU chain will generate a certain swing, causing the PU chain to change from a vertical state to an inclined state. However, the PU chain is always perpendicular to the moving platform and has a certain angle with the relay platform; for the SPS chain, the SPS moving pair in the SPS chain closer to the swinging direction performs telescopic movement, and the remaining SPS chains perform stretching movements. Due to the presence of the lower spherical pair and the upper spherical pair, the SPS chain tilts by a certain amount, increasing the allowable descent amount of the third moving platform. However, restricted by the PU chain, at this time, the second moving platform not only rotates but also translates relative to the fixed platform; at the same time, the PRR moves with the movement of the relay platform.

[0045] Embodiment 4:

[0046] An application of the hybrid platform based on 3SPS-PU-3PRR described in Embodiment 2, where a baby crib that requires fine adjustment is placed on the moving platform, and a control panel is set at the same time. The control panel is connected to all motors. When active rocking is required, the start sequence of the motors is set by the control panel, and the working method described in Embodiment 3 is executed.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A hybrid platform based on 3SPS-PU-3PRR, characterized in that, It includes a fixed platform, a relay platform, and a moving platform. There are three PRR branches connected between the fixed platform and the relay platform, and three SPS branches and one PU branch connected between the relay platform and the moving platform. There are three sets of lead screws on the fixed platform. Each lead screw includes a guide rail, through which a slider is arranged. One end of the guide rail is connected to a motor, and the guide rail is threadedly connected to the slider. The PRR branch includes a first revolute pair, a moving pair rod, and a second revolute pair connected in sequence. The first revolute pair is connected to the slider, and the second revolute pair is connected to the relay platform. The SPS branch includes an upper spherical pair, an SPS moving pair, and a lower spherical pair connected in sequence. The upper spherical pair is connected to the moving platform, and the lower spherical pair is connected to the relay platform. The PU branch includes a PU moving pair and a universal joint connected in sequence. One end of the PU moving pair is fixedly connected to the moving platform, the other end of the PU moving pair is connected to the universal joint, and the universal joint is connected to the relay platform.

2. The hybrid platform based on 3SPS-PU-3PRR according to claim 1, characterized in that, The fixed platform and the relay platform are in the same plane, or the planes where they are located are parallel to each other.

3. The hybrid platform based on 3SPS-PU-3PRR according to claim 1, wherein The first revolute pair is a U-shaped plate. Two plates at the opening of the U-shaped plate are hinged to the slider. The second revolute pair is a U-shaped plate. Two plates at the opening of the U-shaped plate are hinged to the relay platform.

4. The hybrid serial-parallel platform based on 3SPS-PU-3PRR according to claim 1, characterized in that The projection of the fixed platform is a hexagon, the projection of the relay platform is a triangle, and the projection of the moving platform is a triangle. The three sets of lead screws on the fixed platform are spaced apart on six sides. The three PRR branches are respectively connected to three sides of the relay platform. The two ends of the three SPS branches are respectively connected to the acute angles of the relay platform and the moving platform. The two ends of the PU branch are connected to the centers of the relay platform and the moving platform.

5. The hybrid platform based on 3SPS-PU-3PRR according to claim 4, characterized in that, The area of the triangle of the moving platform is smaller than the area of the triangle of the relay platform.

6. The hybrid platform based on 3SPS-PU-3PRR according to claim 1, characterized in that, The PU moving pair is perpendicularly fixed to the moving platform.

7. The hybrid platform based on 3SPS-PU-3PRR according to claim 1, characterized in that, The SPS moving pair and the PU moving pair are both cylinders controlled by motors. The cylinder includes a cylinder rod and a slideway, and the cylinder rod expands and contracts in the slideway.

8. A working method of a hybrid platform based on 3SPS-PU-3PRR, the structure of the hybrid platform is as described in any one of claims 1-7, characterized in that, It includes the following steps: When the hybrid platform driving device makes active driving, when the motors connected to the three sets of lead screws on the fixed platform work, the first revolute pair of the PRR branch slides on the guide rail of the ball screw. The relative position between the first revolute pair and the revolute pair rod changes, and the revolute pair rod swings along with the moving direction of the first revolute pair. Due to the existence of the two revolute pairs, within a certain range of movement of the first revolute pair, only the revolute pair rod swings without driving the relay platform to move relative to the fixed platform. When the first revolute pair moves beyond a certain range, the relay platform moves relative to the fixed platform. At this time, along with the movement of the relay platform, the SPS moving pair in the SPS branch performs telescopic movement. At the same time, the PU moving pair of the PU branch performs telescopic-pulling sliding along with the relay platform. When the moving platform moves and causes the hybrid platform to be driven passively, when the moving platform makes vertical translational movement due to weight change above the moving platform, the PU moving pair of the PU branch performs telescopic-pulling movement along the cylinder slideway in the cylinder, and the SPS moving pair of the SPS branch performs telescopic-pulling movement along the cylinder slideway in the cylinder. At the same time, the relay platform makes a rotational movement along with the movement of the moving pair in the SPS branch. Along with the movement of the relay platform, the revolute pair rod swings to drive the slider to perform reciprocating linear movement along the guide rail. When the change in the weight and centroid above the moving platform causes the moving platform to swing up and down, the PU moving pairs of the PU linkages also perform telescopic motions, and the SPS moving pairs of the SPS linkages also perform telescopic motions. For the SPS linkages closer to the swinging direction of the moving platform, the SPS moving pairs perform telescopic motions, while the moving pairs in the remaining SPS linkages perform stretching motions or remain unchanged. The relay platform rotates with the motion of the SPS linkages, and the rotating pair rod and the slider perform corresponding motions. When the swing amount of the moving platform is too large, due to the presence of universal joints in the PU linkages, the PU linkages will generate a certain swing, causing the PU linkages to change from a vertical state to an inclined state. However, the PU linkages are always perpendicular to the moving platform and have a certain angle with the relay platform; for the SPS linkages, the SPS moving pairs in the SPS linkages closer to the swinging direction perform telescopic motions, and the remaining SPS linkages perform stretching motions. Also, due to the presence of the lower spherical pair and the upper spherical pair, the SPS linkages undergo a certain amount of inclination, increasing the allowable descent amount of the third moving platform. However, restricted by the PU linkages, at this time, the second moving platform not only rotates but also translates relative to the fixed platform; at the same time, the PRR moves with the motion of the relay platform.

9. Application of a hybrid platform based on 3SPS-PU-3PRR, characterized in that, The hybrid platform structure is as described in any one of claims 1-7. Place the object to be adjusted and controlled on the moving platform, and at the same time set up a control panel. The control panel is connected to all motors. When active swinging is required, the control panel sets the startup sequence of the motors and executes the method as described in claim 8.

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