A hydraulically driven three-degree-of-freedom parallel wrist mechanism platform

Abstract

A hydraulically driven three-degree-of-freedom parallel wrist mechanism platform, which relates to the field of humanoid robots. The present invention solves the problem that the existing humanoid robotic arm cannot meet the requirements of the integrated design of multiple hydraulic actuators to achieve compactness and lightweight structure, and it is difficult to simultaneously meet the requirements of the forearm end motion joint having strong load capacity, large range of motion and compact structure function. The forearm skeleton of the present invention is evenly provided with three parallel hydraulic cylinders around it, and the piston rod end of each hydraulic cylinder is equipped with a connecting rod lower Hooke hinge seat, one end of the three connecting rods is respectively connected to the three connecting rod lower Hooke hinge seats, and the other end is respectively connected to the three connecting rods with decomposition ball joints, a middle guide rail mounting seat is installed at the center of the static platform end face, and a decomposition ball joint connected to the middle guide rail mounting seat and the rotating center of the moving platform is installed at the center of the wrist moving platform end face. The present invention is used to meet the requirements of the integrated design of multiple hydraulic actuators to achieve compactness and lightweight structure.

Description

Technical Field

[0001] The invention relates to the field of humanoid robots, and in particular to a hydraulically driven three-degree-of-freedom parallel wrist mechanism platform. Background Art

[0002] Humanoid robot technology is increasingly being used in many fields such as industry, service industry, and agriculture. In the field of humanoid robots, the design requirements and structural compactness of the robot arm are higher than those of industrial robots. Since the robot arm of a humanoid robot is required to have the ability to adapt to operations in unstructured environments and have movement capabilities similar to or superior to those of humans, the robot arm of a humanoid robot is required to have a greater load capacity and a larger range of motion. Therefore, referring to the configuration of the degrees of freedom of the human arm, the robot arm should have at least seven degrees of freedom, and the forearm at the end should have at least three degrees of freedom arranged at the wrist, which is a necessary condition to ensure that the end effector can achieve any position and posture. Since the forearm is located at the end of the entire robot arm, following the general design principles of the robot arm, the end mass should be reduced as much as possible to ensure the stability and control accuracy of the robot arm system.

[0003] At present, there are two main driving modes for humanoid robot arms. One is electric drive. Each joint of the robot arm is controlled by a servo motor. It has the advantages of high integration, simple control, and low cost, but the motor power density is low and the system frequency response is low, which is not suitable for large load working environments. The other is hydraulic drive, which has the advantages of high power density, large load, and good impact resistance. However, in terms of integration, the traditional hydraulic actuator system is difficult to integrate and has a large volume. Therefore, there are not many applications of hydraulic actuators in robot arm systems. At the same time, in terms of degree of freedom arrangement, the degree of freedom arrangement of general traditional industrial robot arms is a series structure arrangement, which requires the base driver to have sufficient load capacity, and the driver close to the end effector must be lightweight. Therefore, if the general series structure is to meet a sufficiently large load capacity, its overall size is very large. The other degree of freedom arrangement is a parallel structure arrangement. Under the same driver condition, it can achieve a working condition that supports a larger load, but its motion workspace is generally not as good as the series structure.

[0004] Based on the above technical research background of traditional robotic arms, the following problems need to be solved: First, how to realize the integrated design of multiple hydraulic actuators to achieve compactness and lightweight structure; second, the mechanism design of high stiffness and sufficient working space for the end motion joint of the forearm. While meeting the required load capacity and range of motion, the structure should be as compact as possible to improve the end control accuracy.

[0005] In summary, the existing humanoid robotic arms cannot meet the requirements of multiple hydraulic actuators integrated design to achieve compactness and lightness of structure, and it is difficult to simultaneously meet the requirements of strong load capacity, large range of motion and compact structure of the forearm end motion joint. Summary of the invention

[0006] The purpose of the present invention is to solve the problems that the existing humanoid robotic arms cannot meet the integrated design of multiple hydraulic actuators to achieve compactness and lightweight structure, and it is difficult to simultaneously meet the requirements of strong load capacity, large range of motion and compact structure functions of the forearm terminal motion joint, and thus provide a hydraulically driven three-degree-of-freedom parallel wrist mechanism platform.

[0007] The technical solution of the present invention is:

[0008] A hydraulically driven three-degree-of-freedom parallel wrist mechanism platform, which includes a wrist moving platform 1, a static platform, an elbow joint connector 10, a moving platform rotation center decomposition ball joint 16, a middle guide rail mounting seat 18, three connecting rods connecting the decomposition ball joint 2, three connecting rods and three connecting rod lower Hooke's hinge machine seats 15, one end of the wrist moving platform 1 is connected to the end effector, and the other end of the wrist moving platform 1 is evenly installed with three connecting rods connecting the decomposition ball joint 2 along the circumferential direction. The static platform is arranged on the side of the wrist moving platform 1 away from the end effector. The static platform includes a forearm skeleton 9 and three hydraulic cylinders 14. Three parallel hydraulic cylinders 14 are evenly arranged around the forearm skeleton 9 along the circumferential direction. A connecting rod lower Hooke's hinge machine seat 15 is installed at the end of the piston rod of each hydraulic cylinder 14. The initial angle of the connecting rod is spirally arranged, and the directions of the three connecting rods are all in the same spiral direction in the entire motion space. One end of the three connecting rods is respectively connected to the three connecting rod lower Hooke's hinge machine seats The wrist movable platform 1 is connected to the wrist movable platform 1 by the hook hinge seat 15, and the other ends of the three connecting rods are respectively connected to the three connecting rod decomposition ball joints 2. A middle guide rail mounting seat 18 is installed at the center of the end surface of one side of the static platform close to the wrist movable platform 1. A moving platform rotation center decomposition ball joint 16 is installed at the center of the end surface of the wrist movable platform 1 close to the static platform. The moving platform rotation center decomposition ball joint 16 is connected to the top of the middle guide rail mounting seat 18. The three guide rails on the middle guide rail mounting seat 18 are respectively slidably connected to the sliders on the three connecting rod lower Hook hinge seat 15 for rotation. When the wrist movable platform 1 is required to rotate around the moving platform rotation center decomposition ball joint 16, the three hydraulic cylinders 14 cooperate with each other for coupling driving, and the piston rods of the three hydraulic cylinders 14 respectively drive the three connecting rods to move through the three connecting rod lower Hook hinge seat 15, and then drive the wrist movable platform 1 to move through the three connecting rod connected decomposition ball joints 2, and transmit power to the wrist joint to realize the angular rotation of the wrist in three directions.

[0009] Further, the connecting rod includes an upper half-split connecting rod 3, a Hooke joint 4 on the connecting rod, a lower half-split connecting rod 5, a Hooke joint 6 on the lower connecting rod, and two split connecting rod connecting screws. The upper half-split connecting rod 3 and the lower half-split connecting rod 5 are two half-split connecting rod structures with symmetrical structures. The half-split connecting rod structure includes a centrally formed arc-shaped rod and two right-angled rods. Two right-angled rods are perpendicularly connected to the outer sides of both ends of the centrally formed arc-shaped rod. The centrally formed arc-shaped rod of the upper half-split connecting rod 3 is fixedly connected to the centrally formed arc-shaped rod of the lower half-split connecting rod 5 through two split connecting rod connecting screws. The two end portions of the assembled upper half-split connecting rod 3 and lower half-split connecting rod 5 respectively form two 'U'-shaped structures. The Hooke joint 4 on the connecting rod and the Hooke joint 6 on the lower connecting rod are respectively rotatably installed at the openings of the two 'U'-shaped structures.

[0010] Further, the Hooke joint 4 on the connecting rod and the Hooke joint 6 on the lower connecting rod have the same structure. The Hooke joint 4 on the connecting rod includes a rectangular connecting block and an axially connecting axle pin. An axially matching pin hole for the axially connecting axle pin is machined along the length direction on the rectangular connecting block. The axially connecting axle pin is inserted into the axially matching pin hole. Both ends of the axially connecting axle pin are rotatably connected to the assembly pin holes on both sides of the 'U'-shaped structure. A radially penetrating pin hole perpendicular to the axially matching pin hole is machined along the width direction on the rectangular connecting block. A transition round hole coaxial with the radially penetrating pin hole is machined in the middle of the axially connecting axle pin.

[0011] Further, the connecting rod connecting split ball joint 2 includes a first split Hooke joint and a first revolute pair. The first split Hooke joint includes a 'U'-shaped upper mounting bracket and a radially connecting axle pin. The radially connecting axle pin is sequentially inserted into the axially matching pin hole of the rectangular connecting block and the transition round hole of the axially connecting axle pin. Both ends of the radially connecting axle pin are rotatably connected to the assembly pin holes on both sides of the 'U'-shaped upper mounting bracket. The first revolute pair includes an upper deep groove ball bearing, a lower deep groove ball bearing, a first positioning screw, a first positioning nut, and a first gasket. Three pairs of bearing accommodating grooves are machined along the radial direction on the upper and lower end faces of the wrist moving platform 1. The upper bearing accommodating groove and the lower bearing accommodating groove in each pair of bearing accommodating grooves are communicated through a moving platform assembly hole at the center. The upper deep groove ball bearing and the lower deep groove ball bearing are respectively installed in the upper bearing accommodating groove and the lower bearing accommodating groove. One end of the first positioning screw is fixedly connected to the 'U'-shaped upper mounting bracket. The other end of the first positioning screw sequentially passes through the lower deep groove ball bearing, the moving platform assembly hole, the upper deep groove ball bearing, and the first gasket and is screwed to the first positioning nut.

[0012] Further, the lower Hooke hinge machine base 15 of the connecting rod includes a piston rod connecting portion and a disassembled lower Hooke hinge. The piston rod connecting portion includes a piston rod connecting plate, a locking nut, and an L-shaped support plate. A piston rod assembly hole is machined in the center of the piston rod connecting plate. The piston rod connecting plate is sleeved on the end of the piston rod of the hydraulic cylinder 14. External threads are machined on the end of the piston rod. The piston rod connecting plate is axially positioned by a piston rod shoulder. The piston rod connecting plate is connected to the piston rod by a locking nut. One end face of the side of the piston rod connecting plate is perpendicularly and fixedly connected to one end of the L-shaped support plate. The other end of the L-shaped support plate is connected to the disassembled lower Hooke hinge. The disassembled lower Hooke hinge is a 'U'-shaped upper mounting bracket. The 'U'-shaped upper mounting bracket is rotatably connected to the axial connecting pin of the lower Hooke hinge 6 of the connecting rod through the assembly shaft holes on both sides. A slider that mates with the guide rail of the middle guide rail mounting seat 18 is provided on one side of the piston rod connecting plate close to the middle guide rail mounting seat 18.

[0013] Further, the decomposition ball hinge 16 at the rotary center of the moving platform includes a second disassembled Hooke hinge and a second rotary pair. The second disassembled Hooke hinge includes a 'U'-shaped center mounting bracket and a cross shaft 17 at the rotary center of the moving platform. The cross shaft 17 at the rotary center of the moving platform is rotatably connected to the assembly shaft holes on both sides of the 'U'-shaped center mounting bracket through one of its center pins. A pair of connecting ear plates is provided at the center of the end face on one side of the wrist moving platform 1 close to the static platform. Ear plate connection pin holes matching the cross shaft 17 at the rotary center of the moving platform are machined on the connecting ear plates. The cross shaft 17 at the rotary center of the moving platform is rotatably connected to the ear plate connection pin holes of the two connecting ear plates through the other center pin. The second rotary pair includes a bearing seat, a bearing end cover, a deep groove ball bearing at the rotary center, a second positioning screw, a second positioning nut, and a second gasket. One end of the second positioning screw is fixedly connected to the 'U'-shaped center mounting bracket. External threads are machined on the other end of the second positioning screw. The other end of the second positioning screw sequentially passes through the central hole of the bearing end cover, the deep groove ball bearing at the rotary center, and the second gasket and is screwed to the second positioning nut. The bearing seat is a hollow cylindrical structure with one end open. The bottom of the bearing seat is coaxially installed in the bearing seat assembly cavity at the top of the middle guide rail mounting seat 18. The deep groove ball bearing at the rotary center is installed in the inner hole of the bearing seat. The bearing end cover is connected to the bearing seat by connecting screws.

[0014] Further, the arrangement form of the three symmetric connecting rods connecting the moving platform and the static platform is a positive spiral structure or a negative spiral structure.

[0015] Furthermore, the forearm frame 9 and the cylinder bodies of the three hydraulic cylinders 14 are processed into a static platform frame by using additive manufacturing integrated molding technology. A high-pressure oil circuit inlet 7 and a low-pressure oil circuit inlet 8 are provided on the forearm frame 9. The high-pressure oil circuit inlet 7 is connected to the rod chambers of the three hydraulic cylinders 14 respectively through the first oil circuit, and the low-pressure oil circuit inlet 8 is connected to the rodless chambers of the three hydraulic cylinders 14 respectively through the second oil circuit. A servo valve 13 is provided on both the first oil circuit and the second oil circuit. The high-pressure oil circuit inlet 7 is connected to the high-pressure end of the external hydraulic oil pump, and the low-pressure oil circuit inlet 8 is connected to the return oil end of the external high-pressure oil pump.

[0016] Furthermore, the static platform also includes three displacement sensors 11, which are respectively installed at the ends of the rodless cavities of the three hydraulic cylinders 14, and the measuring elements of the displacement sensors 11 extend into the rodless cavities of the hydraulic cylinders 14 and are arranged opposite to the piston rods.

[0017] Furthermore, the static platform also includes six oil pressure sensors 12 . Two oil pressure sensors 12 are installed on the cylinder body of each hydraulic cylinder 14 . The measuring elements of the two oil pressure sensors 12 extend into the rod cavity and the rodless cavity of the hydraulic cylinder 14 respectively.

[0018] Compared with the prior art, the present invention has the following effects:

[0019] 1. The present invention adopts a hydraulically driven three-degree-of-freedom parallel wrist mechanism platform. The parallel structure formed by the hydraulic cylinder driving the wrist platform through a connecting rod has the advantages of compact structure, large range of motion, light weight, large driving force, high rigidity and fast response. It can achieve higher hydraulic load capacity on a forearm structure of limited size and mass.

[0020] 2. The present invention adopts a hydraulically driven three-degree-of-freedom parallel wrist mechanism platform and uses additive manufacturing integrated molding technology to carry out the structural design and processing of the hydraulic cylinder skeleton. The three hydraulic cylinders and auxiliary structures are arranged symmetrically, the structure is compact, the installation and disassembly are convenient, the oil circuit layout is more reasonable, the material is increased to a minimum, the weight is light, and the load on the end system of the robotic arm can be reduced, and the response speed can be improved.

[0021] 3. The present invention adopts a hydraulically driven three-degree-of-freedom parallel wrist mechanism platform, and the hydraulic cylinder control adopts closed-loop servo control to achieve high position stiffness and realize precise position servo control of the wrist moving platform.

[0022] 4. The present invention adopts a hydraulically driven three-degree-of-freedom parallel wrist mechanism platform, which can realize the end of the robotic arm having a movement form similar to that of the human arm wrist. At the same time, the structure is compact and the parallel structure adopted improves the mechanism stiffness and load capacity, and can provide a solution for replacing the forearm structure of various hydraulic robotic arms. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural composition diagram of the hydraulically driven three-degree-of-freedom parallel wrist mechanism platform of the present invention;

[0024] Figure 2 It is a mechanism motion principle diagram of the hydraulically driven three-degree-of-freedom parallel wrist mechanism platform of the present invention;

[0025] Figure 3 Schematic diagram of the initial posture of the hydraulically driven three-degree-of-freedom parallel wrist mechanism platform of the present invention;

[0026] Figure 4 Schematic diagram of the general motion posture of the hydraulically driven three-degree-of-freedom parallel wrist mechanism platform of the present invention;

[0027] Figure 5 It is a schematic diagram of the hydraulically driven three-degree-of-freedom parallel wrist mechanism platform of the present invention rotating around the pitch axis;

[0028] Figure 6 It is a schematic diagram of the hydraulically driven three-degree-of-freedom parallel wrist mechanism platform of the present invention rotating around the roll axis;

[0029] Figure 7 It is a schematic diagram of the rotation of the hydraulically driven three-degree-of-freedom parallel wrist mechanism platform around the yaw axis of the present invention.

[0030] In the figure: 1- wrist moving platform; 2- connecting rod connecting decomposition ball joint; 3- upper half split connecting rod; 4- connecting rod upper Hook's hinge; 5- lower half split connecting rod; 6- connecting rod lower Hook's hinge; 7- high pressure oil circuit oil inlet; 8- low pressure oil circuit oil inlet; 9- forearm skeleton; 10- elbow joint connector; 11- displacement sensor; 12- oil pressure sensor; 13- servo valve; 14- hydraulic cylinder; 15- connecting rod lower Hook's hinge machine seat; 16- moving platform rotation center decomposition ball joint; 17- moving platform rotation center cross axis; 18- middle guide rail mounting seat. DETAILED DESCRIPTION

[0031] Specific implementation method 1: Combination Figures 1 to 7The present embodiment is described. The present embodiment is a hydraulically driven three-degree-of-freedom parallel wrist mechanism platform, which includes a wrist moving platform 1, a static platform, an elbow joint connector 10, a moving platform rotation center decomposition ball joint 16, a middle guide rail mounting seat 18, three connecting rods connecting the decomposition ball joint 2, three connecting rods and three connecting rod lower Hooke's hinge machine seats 15. One end of the wrist moving platform 1 is connected to the end effector, and the other end of the wrist moving platform 1 is evenly installed with three connecting rods connecting the decomposition ball joint 2 along the circumferential direction. The static platform is arranged on the side of the wrist moving platform 1 away from the end effector. The static platform includes a forearm skeleton 9 and three hydraulic cylinders 14. Three parallel hydraulic cylinders 14 are evenly arranged around the forearm skeleton 9 along the circumferential direction. A connecting rod lower Hooke's hinge machine seat 15 is installed on the end of the piston rod of each hydraulic cylinder 14. The initial angles of the connecting rods are arranged in a spiral shape, and the directions of the three connecting rods are all in the same spiral direction in the entire motion space. One end of the three connecting rods is respectively It is connected to the three-link Hooke's hinge seat 15, and the other ends of the three connecting rods are respectively connected to the three-link decomposition ball joint 2. A middle guide rail mounting seat 18 is installed at the center of the end surface of the static platform close to the wrist moving platform 1. A moving platform rotation center decomposition ball joint 16 is installed at the center of the end surface of the wrist moving platform 1 close to the static platform. The moving platform rotation center decomposition ball joint 16 is connected to the top of the middle guide rail mounting seat 18, and the three guide rails on the middle guide rail mounting seat 18 are respectively slidably connected to the sliders on the three-link Hooke's hinge seat 15. When the wrist moving platform 1 is required to rotate around the moving platform rotation center decomposition ball joint 16, the three hydraulic cylinders 14 cooperate with each other for coupling driving, and the piston rods of the three hydraulic cylinders 14 respectively drive the three connecting rods to move through the three-link Hooke's hinge seat 15, and then drive the wrist moving platform 1 to move through the three-link decomposition ball joint 2, and transmit power to the wrist joint to realize the angular rotation of the wrist in three directions.

[0032] In this embodiment, pitch is the rotation around the X-axis (pitch), such as Figure 5 As shown. Roll is the left-right rotation (yaw) around the Z axis, as shown Figure 6 As shown. Yaw is the rotation (roll) around the Y axis, as shown Figure 7 shown.

[0033] In this embodiment, the four decomposed ball joints on the wrist moving platform 1 include a moving platform rotation center decomposed ball joint 16 and three connecting rods connecting the decomposed ball joints 2. It can meet the requirements of the three-direction rotational freedom of the forearm wrist of the robot arm and high load capacity. The four decomposed ball joints are decomposed into a Hooke's joint and a slewing pair. The slewing pair uses a deep groove ball bearing with a double-end support structure. The Hooke's joint uses a compact sliding bearing structure, which increases the rotation range of three angles and has a small installation size, which can replace the general ball joint.

[0034] In this embodiment, the elbow joint connector 10 is an independent component, and the adapter can be replaced according to the actual elbow joint structure of the upper arm. The wrist moving platform 1 can be connected to the end effector or quickly disassembled using a flange interface.

[0035] Specific Embodiment 2: Figure 1 This embodiment will be described. The connecting rod of this embodiment includes an upper half-split connecting rod 3, a Hooke joint 4 on the connecting rod, a lower half-split connecting rod 5, a Hooke joint 6 on the lower connecting rod, and two split connecting rod connecting screws. The upper half-split connecting rod 3 and the lower half-split connecting rod 5 are two semi-split connecting rod structures with symmetrical structures. The semi-split connecting rod structure includes a centrally formed arc-shaped rod and two right-angled rods. Two right-angled rods are perpendicularly connected to the outer sides of both ends of the centrally formed arc-shaped rod. The centrally formed arc-shaped rod of the upper half-split connecting rod 3 is fixedly connected to the centrally formed arc-shaped rod of the lower half-split connecting rod 5 through two split connecting rod connecting screws. After assembly, the two ends of the upper half-split connecting rod 3 and the lower half-split connecting rod 5 respectively form two 'U'-shaped structures. The Hooke joint 4 on the connecting rod and the Hooke joint 6 on the lower connecting rod are respectively rotatably installed at the openings of the two 'U'-shaped structures. With such a setting, the power and motion are transmitted to the connecting rod composed of the upper half-split connecting rod 3 and the lower half-split connecting rod 5 through the Hooke joint 6 on the lower connecting rod, and finally the wrist moving platform 1 is driven to rotate around the decomposition ball joint 16 of the moving platform rotation center through the connecting rod connection decomposition ball joint 2. Among them, the connecting rod is optimized to be composed of two semi-connecting rod structures, namely the upper half-split connecting rod 3 and the lower half-split connecting rod 5, to realize the installation of the cross shaft assembly of the Hooke joint; the connecting rod for power transmission is split into two symmetrical parts, and is connected through the cross shaft joint of the Hooke joint and the screw, solving the problem that the two directions of the Hooke joint cannot be structurally closed at the same time during installation. The other compositions and connection relationships are the same as those in Specific Embodiment 1.

[0036] Specific Embodiment 3: Figure 1 This embodiment will be described. The Hooke joint 4 on the connecting rod and the Hooke joint 6 on the lower connecting rod of this embodiment have the same structure. The Hooke joint 4 on the connecting rod includes a rectangular connecting block and an axial connecting shaft pin. An axial pin hole matching the axial connecting shaft pin is machined along the length direction on the rectangular connecting block. The axial connecting shaft pin is inserted into the axial pin hole. Both ends of the axial connecting shaft pin are respectively rotatably connected to the assembly pin holes on both sides of the 'U'-shaped structure. A radial pin hole perpendicular to and penetrating the axial pin hole is machined along the width direction on the rectangular connecting block. A transition round hole coaxial with the radial pin hole is machined in the middle of the axial connecting shaft pin. The other compositions and connection relationships are the same as those in Specific Embodiment 1 or 2.

[0037] Specific Embodiment 4: Figure 1To describe this embodiment, the link-connected split ball hinge 2 of this embodiment includes a first split Hooke's joint and a first revolute pair. The first split Hooke's joint includes a 'U'-shaped upper mounting bracket and a radial connecting pin. The radial connecting pin is sequentially inserted into the axial pin hole of the rectangular connecting block and the transition round hole of the axial connecting pin. Both ends of the radial connecting pin are rotatably connected to the assembly shaft holes on both sides of the 'U'-shaped upper mounting bracket. The first revolute pair includes an upper deep groove ball bearing, a lower deep groove ball bearing, a first positioning screw, a first positioning nut and a first gasket. Three pairs of bearing accommodation grooves are machined radially on the upper and lower end faces of the wrist moving platform 1. The centers of the upper bearing accommodation groove and the lower bearing accommodation groove in each pair of bearing accommodation grooves are connected through the moving platform assembly hole. The upper deep groove ball bearing and the lower deep groove ball bearing are respectively installed in the upper bearing accommodation groove and the lower bearing accommodation groove. One end of the first positioning screw is fixedly connected to the 'U'-shaped upper mounting bracket. The other end of the first positioning screw sequentially passes through the lower deep groove ball bearing, the moving platform assembly hole, the upper deep groove ball bearing and the first gasket and is screwed to the first positioning nut. With such a setting, the ball hinge freedom of the wrist moving platform 1 is decomposed into a Hooke's joint plus a revolute hinge, realizing the function substitution of the ball hinge. Compared with the standard ball hinge, on the one hand, the range of rotational motion in three angles can be increased, and on the other hand, the installation size can be reduced. Other compositions and connection relationships are the same as those in the first, second or third specific embodiments.

[0038] Specific Embodiment Five: With reference to Figure 1 To describe this embodiment, the connecting rod lower Hooke's joint base 15 of this embodiment includes a piston rod connecting part and a split lower Hooke's joint. The piston rod connecting part includes a piston rod connecting plate, a locking nut and an L-shaped support plate. A piston rod assembly hole is machined in the center of the piston rod connecting plate. The piston rod connecting plate is sleeved on the end of the piston rod of the hydraulic cylinder 14. External threads are machined on the end of the piston rod. The piston rod connecting plate is axially positioned through the piston rod shoulder. The piston rod connecting plate is connected to the piston rod through the locking nut. The side end face of the piston rod connecting plate is vertically and fixedly connected to one end of the L-shaped support plate. The other end of the L-shaped support plate is connected to the split lower Hooke's joint. The split lower Hooke's joint is a 'U'-shaped upper mounting bracket. The 'U'-shaped upper mounting bracket is rotatably connected to the axial connecting pin of the connecting rod lower Hooke's joint 6 through the assembly shaft holes on both sides. A slider that matches the guide rail of the middle guide rail mounting seat 18 is provided on one side of the piston rod connecting plate close to the middle guide rail mounting seat 18. Other compositions and connection relationships are the same as those in the first, second, third or fourth specific embodiments.

[0039] Specific Embodiment Six: With reference to Figure 1To describe this embodiment, the slewing center decomposition ball joint 16 of the moving platform in this embodiment includes a second decomposition Hooke joint and a second slewing pair. The second decomposition Hooke joint includes a 'U'-shaped center mounting frame and a cross shaft 17 at the slewing center of the moving platform. The cross shaft 17 at the slewing center of the moving platform is rotatably connected to the assembly shaft holes on both sides of the 'U'-shaped center mounting frame through one of its central shaft pins. On the end face center of the wrist moving platform 1 close to the static platform side, there are a pair of connecting ear plates, and ear plate connection pin holes matching the cross shaft 17 at the slewing center of the moving platform are machined on the connecting ear plates. The cross shaft 17 at the slewing center of the moving platform is rotatably connected to the ear plate connection pin holes of the two connecting ear plates through the other central shaft pin. The second slewing pair includes a bearing seat, a bearing end cover, a deep groove ball bearing at the slewing center, a second positioning screw, a second positioning nut, and a second gasket. One end of the second positioning screw is fixedly connected to the 'U'-shaped center mounting frame, and the other end of the second positioning screw is machined with an external thread. The other end of the second positioning screw sequentially passes through the central hole of the bearing end cover, the deep groove ball bearing at the slewing center, and the second gasket and is screwed to the second positioning nut. The bearing seat is a hollow cylindrical structure with one end open. The bottom of the bearing seat is coaxially installed in the bearing seat assembly cavity at the top of the middle guide rail mounting seat 18. The deep groove ball bearing at the slewing center is installed in the inner hole of the bearing seat, and the bearing end cover is connected to the bearing seat through connecting screws. With such a setting, the ball joint is split into a structure of a Hooke joint plus a double-end supported slewing bearing for the slewing center decomposition ball joint 16 of the moving platform and the connecting rod connection decomposition ball joint 2, increasing the movement range of the three angles, enabling the connecting rod to reach a movement range close to ±90°, and at the same time reducing the installation size. The double-end supported slewing structure increases the joint load capacity. The other components and connection relationships are the same as those in the first, second, third, fourth, or fifth specific embodiments.

[0040] In this embodiment, the middle guide rail mounting seat 18 is arranged in a symmetric structure to form a central triangular star-shaped support column without redundant structures and can ensure the structural stiffness and strength. The three corners of the central triangular star-shaped support column serve as the guide rails that slide配合 with the sliders on the three connecting rod lower Hooke joint bases 15. When the piston rods of the three hydraulic cylinders 14 drive the three connecting rods to perform linear reciprocating motions along the axis direction respectively through the three connecting rod lower Hooke joint bases 15, the three connecting rod lower Hooke joint bases 15 slide配合 with the guide rails of the central triangular star-shaped support column.

[0041] Specific embodiment seven: Combine Figure 1 To describe this embodiment, the connection form of the connecting rod in this embodiment is a positive spiral structure or a reverse spiral structure. With such a setting, it can be adjusted to a positive spiral structure or a reverse spiral structure according to the specific structure. The other components and connection relationships are the same as those in the first, second, third, fourth, fifth, or sixth specific embodiments.

[0042] Specific embodiment eight: Combine Figure 1This embodiment is described. The forearm frame 9 and the cylinder bodies of the three hydraulic cylinders 14 of this embodiment are processed into a static platform frame by using additive manufacturing integrated molding technology. The forearm frame 9 is provided with a high-pressure oil circuit inlet 7 and a low-pressure oil circuit inlet 8. The high-pressure oil circuit inlet 7 is connected to the rod chambers of the three hydraulic cylinders 14 through the first oil circuit, and the low-pressure oil circuit inlet 8 is connected to the rodless chambers of the three hydraulic cylinders 14 through the second oil circuit. A servo valve 13 is provided on both the first oil circuit and the second oil circuit. The high-pressure oil circuit inlet 7 is connected to the high-pressure end of the external hydraulic oil pump, and the low-pressure oil circuit inlet 8 is connected to the return oil end of the external high-pressure oil pump to provide oil supply pressure for the three hydraulic cylinders. In this way, the displacement of the piston rod of the hydraulic cylinder 14 is controlled by the servo valve 13. The static platform is processed and manufactured by using additive manufacturing integrated molding technology. The cylinder bodies of the three hydraulic cylinders are symmetrically arranged and connected to each other through the oil circuit to form a basic frame. The oil circuit does not need to be additionally designed and processed, and the structural materials are minimized. The other components and connection relationships are the same as those of the first, second, third, fourth, fifth, sixth or seventh specific embodiments.

[0043] In this embodiment, three parallel and identical hydraulic cylinders 14 are integrated with the forearm skeleton 9 to form a static platform of parallel structure, and the integrated additive manufacturing technology is adopted for design, manufacturing and processing; the piston rod of the hydraulic cylinder 14 is connected to the connecting rod connection decomposition ball joint 2 on the wrist moving platform 1 through a symmetrically split two-force rod, and the piston rod of the hydraulic cylinder 14 drives the connecting rod, and then drives the wrist moving platform 1, so that the three hydraulic cylinders 14 are coupled to drive the wrist moving platform 1 to move. The mechanical arm forearm with the above technical solutions has the advantages of compact structure, strong load capacity, detachability, high power density, etc.

[0044] Specific implementation method nine: Combination Figure 1 To explain this embodiment, the static platform of this embodiment further includes three displacement sensors 11, which are respectively mounted at the ends of the rodless cavities of the three hydraulic cylinders 14, and the measuring elements of the displacement sensors 11 extend into the rodless cavities of the hydraulic cylinders 14 and are arranged opposite to the piston rods. In this arrangement, the displacement of the piston rods of the hydraulic cylinders 14 is monitored by the displacement sensors 11. Other components and connection relationships are the same as those of the specific embodiments 1, 2, 3, 4, 5, 6, 7 or 8.

[0045] Specific implementation method ten: Combination Figure 1To explain this embodiment, the static platform of this embodiment also includes six oil pressure sensors 12, and two oil pressure sensors 12 are installed on the cylinder body of each hydraulic cylinder 14, and the measuring elements of the two oil pressure sensors 12 extend into the rod chamber and the rodless chamber of the hydraulic cylinder 14 respectively. In this way, the pressure of the two chambers of the hydraulic cylinder 14 is monitored by the oil pressure sensor 12, and the existing controller on the market is used to monitor the pressure of the two chambers of the system hydraulic cylinder, the system high pressure and the piston rod displacement to control the servo valve 13 to perform servo control of the hydraulic cylinder 14. Other components and connection relationships are the same as those of the first, second, third, fourth, fifth, sixth, seventh, eighth or ninth embodiment.

[0046] How it works

[0047] Combination Figures 1 to 7 The working principle of the hydraulically driven three-degree-of-freedom parallel wrist mechanism platform of the present invention is described as follows:

[0048] Reference Figure 1 , is a mechanism motion principle diagram of the hydraulically driven three-degree-of-freedom parallel wrist mechanism platform of the present invention, wherein the mechanism elements mainly include: a static platform frame formed by B1B2B3 ( Figure 1 The dotted triangle), hydraulic cylinders B1C1, B2C2, B3C3 (B i C i , i=1,2,3), Hooke hinges C1, C2, C3 (C i , i=1,2,3), driving connecting rods C1A1, C2A2, C3A3 (C i A i , i=1,2,3), wrist moving platform C4-A1A2A3 (C4 is the rotation center of the wrist joint), and the ball joints C4, A1, A2, A3 (A i , i=1,2,3). The hydraulic cylinder is controlled by the servo valve to perform servo linear motion. The three hydraulic cylinders are arranged symmetrically. The connecting rod parameters in the three directions are the same. The initial angle of the connecting rod is arranged in a spiral shape (it can be adjusted to a positive spiral structure or a reverse spiral structure according to the specific structure), and the three connecting rods C in the entire motion space i A i The directions of the three hydraulic cylinders B are all in the same spiral direction. When the wrist moving platform C4-A1A2A3 is required to rotate around the rotation center C4, the three hydraulic cylinders B i C i The two are coupled and driven by a certain control algorithm, respectively through the Hooke hinge C i Drive connecting rod C i A i Movement, then through the ball joint A i It drives the wrist dynamic platform C4-A1A2A3 to move and transmits power to the wrist joint to achieve angular rotation of the wrist in three directions.

[0049] refer to Figures 3 to 7 , which is a schematic diagram of the three-axis rotation of the hydraulically driven three-degree-of-freedom parallel wrist mechanism platform of the present invention, showing the initial posture of the platform (refer to Figure 3 ), general sports posture (refer to Figure 4 ), the posture of rotation around the pitch axis (refer to Figure 5 ), the posture of rotation around the roll axis (refer to Figure 6 ), the posture of rotation around the yaw axis (refer to Figure 7 ).

[0050] The initial posture indicates that in the initial motion state, the piston rods of the three hydraulic cylinders 14 are all in the middle position of the hydraulic stroke, and the initial angles in all directions are 0 at this time; the general motion posture indicates the expected displacement state of the piston rods of the three hydraulic cylinders 14 of the wrist moving platform 1 in the expected position; the posture of rotation around pitch indicates the expected displacement state of the piston rods of the three hydraulic cylinders 14 when the wrist moving platform 1 only rotates around the v-axis of its moving coordinate system; the posture of rotation around roll indicates the expected displacement state of the piston rods of the three hydraulic cylinders 14 when the wrist moving platform 1 only rotates around the w-axis of its moving coordinate system, at this time, the piston rods of the three hydraulic cylinders 14 move synchronously, with the same expected displacement, and the driving connecting rod and the wrist moving platform 1 perform a spiral-like motion; the posture of rotation around yaw indicates the expected displacement state of the piston rods of the three hydraulic cylinders 14 when the wrist moving platform 1 only rotates around the u-axis of its moving coordinate system.

[0051] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A hydraulically driven three-degree-of-freedom parallel wrist mechanism platform, characterized in that: It includes a wrist moving platform (1), a stationary platform, an elbow joint connecting member (10), a decomposition spherical hinge for the rotary center of the moving platform (16), a middle guide rail mounting base (18), three connecting rod connecting decomposition spherical hinges (2), three connecting rods, and three lower Hooke's joint bases (15) of the connecting rods. One end of the wrist moving platform (1) is connected to the end effector. At the other end of the wrist moving platform (1), three connecting rod connecting decomposition spherical hinges (2) are evenly installed along the circumferential direction. The stationary platform is arranged on the side of the wrist moving platform (1) away from the end effector. The stationary platform includes a forearm skeleton (9) and three hydraulic cylinders (14). Around the forearm skeleton (9), three parallel hydraulic cylinders (14) are evenly arranged along the circumferential direction. At the end of the piston rod of each hydraulic cylinder (14), a lower Hooke's joint base (15) of the connecting rod is installed. The initial angles of the three connecting rods are arranged in a spiral shape, and the directions of the three connecting rods are the same spiral direction within the entire movement space. One end of each of the three connecting rods is respectively connected to one of the three lower Hooke's joint bases (15), and the other end of each of the three connecting rods is respectively connected to one of the three connecting rod connecting decomposition spherical hinges (2). At the center of the end face of the stationary platform close to the wrist moving platform (1), a middle guide rail mounting base (18) is installed. At the center of the end face of the wrist moving platform (1) close to the stationary platform, a decomposition spherical hinge for the rotary center of the moving platform (16) is installed. The decomposition spherical hinge for the rotary center of the moving platform (16) is connected to the top of the middle guide rail mounting base (18). The three guide rails on the middle guide rail mounting base (18) are respectively slidably connected to the sliders on the three lower Hooke's joint bases (15). When the wrist moving platform (1) needs to make a rotary motion around the decomposition spherical hinge for the rotary center of the moving platform (16), the three hydraulic cylinders (14) cooperate with each other for coupled drive. The piston rods of the three hydraulic cylinders (14) respectively drive the three connecting rods through the three lower Hooke's joint bases (15), and then drive the wrist moving platform (1) through the three connecting rod connecting decomposition spherical hinges (2), and transmit the power to the wrist joint to realize the angular rotation of the wrist around three directions.

2. The hydraulically driven three-DOF parallel wrist mechanism platform according to claim 1, characterized in that: The connecting rod includes an upper half split connecting rod (3), a connecting rod upper Hooke's joint (4), a lower half split connecting rod (5), a connecting rod lower Hooke's joint (6), and two split connecting rod connecting screws. The upper half split connecting rod (3) and the lower half split connecting rod (5) are two semi-split connecting rod structures with symmetrical structures. The semi-split connecting rod structure includes a middle arc-shaped rod and two right-angle rods integrally formed. At the outer sides of both ends of the middle arc-shaped rod, two right-angle rods are respectively vertically connected. The middle arc-shaped rod of the upper half split connecting rod (3) is fixedly connected to the middle arc-shaped rod of the lower half split connecting rod (5) through two split connecting rod connecting screws. After assembly, the two end parts of the upper half split connecting rod (3) and the lower half split connecting rod (5) respectively form two 'U'-shaped structures. The connecting rod upper Hooke's joint (4) and the connecting rod lower Hooke's joint (6) are respectively rotatably installed at the openings of the two 'U'-shaped structures.

3. The hydraulically driven three-DOF parallel wrist mechanism platform according to claim 2, characterized in that: The upper Hooke's joint (4) of the connecting rod and the lower Hooke's joint (6) of the connecting rod have the same structure. The upper Hooke's joint (4) of the connecting rod includes a rectangular connecting block and an axial connecting pin. An axial pin hole matching the axial connecting pin is machined along the length direction on the rectangular connecting block. The axial connecting pin is inserted into the axial pin hole. Both ends of the axial connecting pin are rotatably connected to the assembly pin holes on both sides of the 'U'-shaped structure. A radial pin hole perpendicular to and penetrating through the axial pin hole is machined along the width direction on the rectangular connecting block. A transition round hole coaxial with the radial pin hole is machined in the middle of the axial connecting pin.

4. The hydraulically driven three-DOF parallel wrist mechanism platform according to claim 3, characterized in that: The connecting rod connecting decomposition spherical joint (2) includes a first decomposition Hooke's joint and a first revolute pair. The first decomposition Hooke's joint includes a 'U'-shaped upper mounting frame and a radial connecting pin. The radial connecting pin is sequentially inserted into the axial pin hole of the rectangular connecting block and the transition round hole of the axial connecting pin. Both ends of the radial connecting pin are rotatably connected to the assembly pin holes on both sides of the 'U'-shaped upper mounting frame. The first revolute pair includes an upper deep groove ball bearing, a lower deep groove ball bearing, a first positioning screw, a first positioning nut and a first gasket. Three pairs of bearing accommodating grooves are machined along the radial direction on the upper and lower end faces of the wrist moving platform (1). The centers of the upper bearing accommodating groove and the lower bearing accommodating groove in each pair of bearing accommodating grooves are communicated through the moving platform assembly hole. The upper deep groove ball bearing and the lower deep groove ball bearing are respectively embedded in the upper bearing accommodating groove and the lower bearing accommodating groove. One end of the first positioning screw is fixedly connected to the 'U'-shaped upper mounting frame. The other end of the first positioning screw sequentially passes through the lower deep groove ball bearing, the moving platform assembly hole, the upper deep groove ball bearing and the first gasket and is screwed to the first positioning nut.

5. A hydraulically driven three-DOF parallel wrist mechanism platform according to claim 3 or 4, characterized in that: The lower Hooke's joint base (15) of the connecting rod includes a piston rod connecting part and a decomposition lower Hooke's joint. The piston rod connecting part includes a piston rod connecting plate, a locking nut and an L-shaped support plate. A piston rod assembly hole is machined in the center of the piston rod connecting plate. The piston rod connecting plate is sleeved on the end of the piston rod of the hydraulic cylinder (14). External threads are machined on the end of the piston rod. The piston rod connecting plate is axially positioned through the piston rod shoulder. The piston rod connecting plate is connected to the piston rod through the locking nut. The side end face of the piston rod connecting plate is vertically and fixedly connected to one end of the L-shaped support plate. The other end of the L-shaped support plate is connected to the decomposition lower Hooke's joint. The decomposition lower Hooke's joint is a 'U'-shaped upper mounting frame. The 'U'-shaped upper mounting frame is rotatably connected to the axial connecting pin of the lower Hooke's joint (6) of the connecting rod through the assembly pin holes on both sides. A slider matching the guide rail of the middle guide rail mounting seat (18) is provided on one side of the piston rod connecting plate close to the middle guide rail mounting seat (18).

6. The hydraulically driven three-DOF parallel wrist mechanism platform according to claim 5, characterized in that: The rotary center decomposition spherical hinge (16) of the moving platform includes a second decomposition Hooke hinge and a second rotary pair. The second decomposition Hooke hinge includes a 'U'-shaped center mounting frame and a cross shaft (17) of the rotary center of the moving platform. The cross shaft (17) of the rotary center of the moving platform is rotatably connected to the assembly shaft holes on both sides of the 'U'-shaped center mounting frame through one of its central shaft pins. On the center of the end face of the wrist moving platform (1) close to the static platform side, there are a pair of connecting ear plates. The ear plate connecting pin holes matching the cross shaft (17) of the rotary center of the moving platform are machined on the connecting ear plates. The cross shaft (17) of the rotary center of the moving platform is rotatably connected to the ear plate connecting pin holes of the two connecting ear plates through the other central shaft pin. The second rotary pair includes a bearing seat, a bearing end cover, a deep groove ball bearing at the rotary center, a second positioning screw, a second positioning nut, and a second gasket. One end of the second positioning screw is fixedly connected to the 'U'-shaped center mounting frame. The other end of the second positioning screw is machined with an external thread. The other end of the second positioning screw sequentially passes through the central hole of the bearing end cover, the deep groove ball bearing at the rotary center, and the second gasket and is screwed with the second positioning nut. The bearing seat is a hollow cylindrical structure with one end open. The bottom of the bearing seat is coaxially installed in the bearing seat assembly cavity at the top of the middle guide rail mounting seat (18). The deep groove ball bearing at the rotary center is installed in the inner hole of the bearing seat. The bearing end cover is connected to the bearing seat through connecting screws.

7. A hydraulically driven three-DOF parallel wrist mechanism platform according to claim 1 or 6, characterized in that: The connecting rod is a positive spiral structure or a negative spiral structure.

8. The hydraulically driven three-DOF parallel wrist mechanism platform according to claim 7, characterized in that: The forearm skeleton (9) and the cylinder bodies of the three hydraulic cylinders (14) are processed into the static platform skeleton by using the additive manufacturing integrated forming technology. The high-pressure oil inlet (7) and the low-pressure oil inlet (8) are provided on the forearm skeleton (9). The high-pressure oil inlet (7) is communicated with the rodless cavities of the three hydraulic cylinders (14) through the first oil circuit respectively. The low-pressure oil inlet (8) is communicated with the rodless cavities of the three hydraulic cylinders (14) through the second oil circuit respectively. Servo valves 13 are provided on both the first oil circuit and the second oil circuit. The high-pressure oil inlet (7) is connected to the high-pressure end of an external hydraulic oil pump. The low-pressure oil inlet (8) is connected to the oil return end of an external high-pressure oil pump.

9. A hydraulically driven three-DOF parallel wrist mechanism platform according to claim 1 or 8, characterized in that: The static platform further includes three displacement sensors (11). The three displacement sensors (11) are respectively installed at the ends of the rodless cavities of the three hydraulic cylinders (14). The measuring element of the displacement sensor (11) extends into the rodless cavity of the hydraulic cylinder (14) and is arranged opposite to the piston rod.

10. The hydraulically driven three-DOF parallel wrist mechanism platform according to claim 9, characterized in that: The static platform further includes six oil pressure sensors (12). Two oil pressure sensors (12) are installed on the cylinder body of each hydraulic cylinder (14). The measuring elements of the two oil pressure sensors (12) respectively extend into the rodless cavity and the rodless cavity of the hydraulic cylinder (14).

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