A four-degree-of-freedom robot end effector driven by parallel rope and lead screw

Abstract

The present invention discloses a four-degree-of-freedom robot end effector driven by a parallel rope and a screw rod, belonging to the technical field of parallel robots, including a rope driving mechanism, a screw motor fixing mechanism, a clamping mechanism and a clamping claw rotating mechanism; the rope driving mechanism includes a first motor drum, a second motor drum, a third motor drum, a fourth motor drum, a positioning plate, a motor base, an anti-jump wire device, a universal guide wheel, and a rope; the screw motor fixing mechanism includes a screw motor, a screw motor base, a thrust bearing, a reducer, a universal joint and a screw rod. The inertial force generated during the movement of the present invention is small, the dynamic response of the moving platform is rapid, the stiffness characteristics and stability are good, and compared with the parallel mechanism with two rotational degrees of freedom and the parallel mechanism with three translational degrees of freedom, the working space of the end effector is greatly expanded.

Description

Technical Field

[0001] The invention relates to the technical field of parallel robots, and in particular to a four-degree-of-freedom robot end effector driven by a hybrid of parallel ropes and lead screws. Background Art

[0002] The rope-driven parallel robot is a parallel robot that uses lightweight, flexible ropes instead of rigid parts as the kinematic chain. The rope-driven parallel robot inherits the high-load configuration advantages of the rigid parallel mechanism, while also having the characteristics of small motion inertia, large workspace, low cost and easy reconfiguration of the rope-driven parallel robot. The rope-driven parallel robot is widely used in industrial assembly, material sorting, medical equipment, aerial operations and other fields due to its high rigidity, high precision and strong load-bearing capacity.

[0003] The patent application with the patent publication number CN112693630A describes a two-rotational freedom rope-driven parallel mechanism. Three sets of rope drive devices and one set of central rigid support devices are connected in parallel to achieve two-rotational freedom movement of the end. However, the pure rope-driven parallel robot has extremely high requirements for rope drive control, which easily causes rope breakage.

[0004] The patent application with the patent publication number CN110315511A describes a parallel mechanism with three degrees of freedom for translation. Passive springs and rigid rods are used to achieve rope tensioning, and three sets of drivers drive the end to translate in three degrees of freedom. The moving platform can achieve rapid translation in three dimensions in space, but each moving branch chain has a parallelogram mechanism that limits the rotation of the moving platform, so that the moving platform cannot rotate but can only move in space. Due to this movement restriction, the parallel mechanism with three degrees of freedom for translation cannot obtain a large working space.

[0005] Compared with the three-degree-of-freedom parallel mechanism, the six-degree-of-freedom parallel mechanism can make the end effector posture more flexible and greatly expand the workspace of the end effector. However, due to its complex structure, it will cause the system center of gravity and inertia of the base robot connected to the mechanism to change in real time. The inertial force during the movement of the mechanism will also have a great impact on the stability of the base robot, which significantly increases the control difficulty of the mechanism. Summary of the invention

[0006] The purpose of the present invention is to provide a four-degree-of-freedom robot end effector driven by a hybrid of parallel ropes and lead screws, which solves the problems of high control requirements and easy breakage of pure rope-driven parallel robots, and can obtain a larger working space while ensuring stability.

[0007] The technical problem to be solved by the present invention can be implemented through the following technical solutions.

[0008] A parallel rope and lead screw hybrid driven four-DOF robot end effector comprises a rope driving mechanism, a lead screw motor fixing mechanism, a clamping mechanism and a clamping claw rotating mechanism;

[0009] The rope drive mechanism comprises a first motor drum, a second motor drum, a third motor drum, a fourth motor drum, a positioning plate, a motor base, an anti-jumping device, a universal guide wheel, and a rope; the first motor drum, the second motor drum, the third motor drum, and the fourth motor drum are fixed on the positioning plate through the motor base; the anti-jumping device is fixed on the positioning plate; the cross section of the motor drum is tangent to the cross section of the rope groove of the anti-jumping device; the universal guide wheel is fixed to the bottom surface of the positioning plate; the starting end of the rope is fixed to the bottom of the drum shaft of the first motor drum, the second motor drum, the third motor drum, and the fourth motor drum, and is led out after winding around the drum shaft, bypassing the rope groove of the anti-jumping device and passing downward through the universal guide wheel;

[0010] The screw motor fixing mechanism includes a screw motor, a screw motor base, a thrust bearing, a reducer, a universal joint and a screw; the screw motor is fixed to the bottom surface of the positioning plate through the screw motor base; the thrust bearing is installed at the output end of the screw motor; one end of the reducer is connected to the output shaft of the screw motor, the other end of the reducer is inserted into the universal joint, and the other end of the universal joint is connected to the screw.

[0011] In the above technical solution, preferably, the anti-jump wire device and the positioning plate are fixed by an anti-jump wire device bracket; and the universal guide wheel and the positioning plate are fixed by a universal guide wheel bracket.

[0012] In the above technical scheme, preferably, the clamping mechanism includes a screw nut, a screw nut platform, a lifting eye screw, a first connecting rod, a second connecting rod, a third connecting rod, a sleeve platform, and a clamping claw; the screw nut is installed on the screw, and the screw nut platform is fixed on the screw nut; the lifting eye screw is symmetrically fixed on the four corner directions of the screw nut; the end of the rope is fixed on the lifting eye screw; one end of the first connecting rod is connected to the screw nut platform, the other end of the first connecting rod is connected to the second connecting rod, the other end of the second connecting rod is connected to the clamping claw, the middle section of the second connecting rod is connected to the sleeve platform, and the clamping claw is connected to the sleeve platform through the third connecting rod.

[0013] In the above technical solution, preferably, a flange bearing is installed at the connection of the platform or the connecting rod, and an axle pin is inserted in the middle of the flange bearing.

[0014] In the above technical solution, preferably, the jaw rotation mechanism includes a sleeve, an end thrust bearing, a deep groove ball bearing and a locking nut; the sleeve, the sleeve platform, the end thrust bearing and the deep groove ball bearing are sequentially inserted into the screw; the locking nut is fixed to the end of the screw and presses against the inner ring of the deep groove ball bearing.

[0015] The advantages of the present invention are as follows:

[0016] 1. The present invention adopts a structure in which four motor reels and one motor-driven lead screw are connected in parallel. The inertial force generated during the movement of the clamp driven by the rope and lead screw is small, so that the dynamic response of the moving platform is fast, the reaction force and reaction torque on the moving base are small, and the change in the position of the center of mass and the rotational inertia of the whole movement is small. The rigid lead screw is added, and the lead screw and the rope together form a tensegrity structure, which increases the support force constraint for the moving platform and improves the rigidity characteristics and stability of the moving platform.

[0017] 2. The cable-screw hybrid drive adopted by the present invention can realize that the gripper has three-dimensional translational freedom and one-dimensional rotational freedom in space, making the robot end effector posture more flexible. Compared with the parallel mechanism with two rotational freedom degrees and the parallel mechanism with three translational freedom degrees, the working space of the end effector is greatly expanded, thereby making the application scenarios of the robot more extensive.

[0018] 3. In the present invention, the screw drive assembly and the rope form a lightweight motion chain, which is used to drive the multi-platform movement, greatly reducing the mass and motion inertia of the parallel robot, making it easy for the parallel robot to achieve higher speed and acceleration, that is, to achieve high dynamic movement, thereby greatly improving the robot's movement efficiency.

[0019] 4. The driving mechanism of the present invention has a simple structure, and the drum and screw drive motors are compactly arranged at the root of the robot, reducing the mass and inertia of the moving parts; at the same time, the drum and screw drive motors are compactly arranged on a positioning plate away from the working environment; the robot's terminal moving parts do not contain motors, which makes the robot mechanism more robust, so the present invention is suitable for complex environments such as aerial operations and plateau exploration. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The figure is a schematic diagram of a quad-rotor UAV equipped with the present invention in an operating state.

[0021] Figure 2 It is a schematic diagram of the overall structure of the present invention.

[0022] Figure 3 It is a longitudinal cross-sectional view of the present invention.

[0023] Figure 4 It is a schematic diagram of the swing of the clamping jaws of the present invention.

[0024] Figure 5 It is a schematic diagram of the clamping jaws of the present invention in an open state.

[0025] Figure 6 It is a schematic diagram of the clamping jaws of the present invention in a closed state.

[0026] Figure 7 It is a schematic diagram of the clamping jaws of the present invention in a rotated and opened state.

[0027] Explanation of the accompanying drawings: 1-first motor drum, 2-second motor drum, 3-third motor drum, 4-fourth motor drum, 5-positioning plate, 6-motor base, 7-anti-jumping device, 8-anti-jumping device bracket, 9-universal guide wheel, 10-universal guide wheel bracket, 11-rope, 12-screw motor, 13-screw motor base, 14-thrust bearing, 15-reducer, 16-universal joint, 17-screw, 18-screw nut, 19-screw nut platform, 20-eye screw, 21-first connecting rod, 22-second connecting rod, 23-third connecting rod, 24-sleeve platform, 25-clamp, 26-flange bearing, 27-axle pin, 28-sleeve, 29-end thrust bearing, 30-deep groove ball bearing, 31-locking nut. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0029] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "set" should be understood in a broad sense, for example, they can be fixedly connected or set, or detachably connected or set, or integrally connected or set. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] The invention discloses a four-degree-of-freedom robot end effector driven by a parallel rope and a lead screw hybrid, comprising a rope driving mechanism, a lead screw motor fixing mechanism, a clamping claw mechanism and a clamping claw rotating mechanism.

[0032] like Figure 1 As shown, it is an operating state of the quad-rotor UAV equipped with the present invention.

[0033] like Figure 2As shown, the rope drive mechanism includes a first motor drum 1, a second motor drum 2, a third motor drum 3, a fourth motor drum 4, a positioning plate 5, a motor base 6, an anti-jumping device 7, an anti-jumping device bracket 8, a universal guide wheel 9, a universal guide wheel bracket 10 and a rope 11. The first motor drum 1, the second motor drum 2, the third motor drum 3 and the fourth motor drum 4 are symmetrically fixed on the four corners of the positioning plate 5 via the motor base 6. The anti-jumping device 7 is symmetrically fixed on the four corners of the positioning plate 5 via the anti-jumping device bracket 8. The universal guide wheel 9 is symmetrically fixed on the four corners of the bottom surface of the positioning plate 5 via the universal guide wheel bracket 10. The cross section of the motor drum is tangent to the cross section of the rope groove of the anti-jumping device 7; the rope 11 starts from the bottom of the drum shaft of the first motor drum 1, the second motor drum 2, the third motor drum 3 and the fourth motor drum 4 respectively, and is led out after being wound coaxially for several turns, bypassing the rope groove of the anti-jumping device 7 and passing downward through the universal guide wheel 9. The motor drum rotates to wind the rope 11 to collect or release the rope, and the anti-jump wire device 7 guides the rope 11 entering the rope groove through the pulley to the rope feeding hole on the positioning plate 5. There are two pulleys on the universal guide wheel 9, the axes of the two pulleys are parallel and the distance between the two rope grooves is enough for the rope 11 to pass through. The universal wheel 9 can rotate in the vertical direction, and the rope 11 passes through the rope feeding hole on the positioning plate 5 and then passes between the two pulleys on the universal guide wheel 9. After winding around the rope groove, it can be guided to any direction.

[0034] like Figure 2 and Figure 3 As shown, the screw motor fixing mechanism includes a screw motor 12, a screw motor base 13, a thrust bearing 14, a reducer 15, a universal joint 16 and a screw 17. The screw motor 12 is fixed to the bottom surface of the positioning plate 5 via the screw motor base 13. The thrust bearing 14 is installed at the output end of the screw motor 12. One end of the reducer 15 is connected to the output shaft of the screw motor 12, and the other end is inserted into the universal joint 16. The other end of the universal joint 16 is connected to the screw 17. After the output shaft of the screw motor 12 is connected to the screw 17 via the reducer and the universal joint, the screw 17 can be driven to rotate. The thrust bearing 14 bears the radial force caused by the load at the output end of the screw motor 12. The universal joint 16 allows the screw 17 to swing in two directions.

[0035] like Figure 2 , Figure 5 and Figure 6As shown, the clamping mechanism includes a screw nut 18, a screw nut platform 19, an eye screw 20, a first connecting rod 21, a second connecting rod 22, a third connecting rod 23, a sleeve platform 24, a clamping jaw 25, a flange bearing 26, and an axle pin 27. The screw nut 18 is assembled on the screw 17. The screw nut platform 19 is fixed on the screw nut 18. The eye screw 20 is symmetrically fixed on the four corners of the screw nut platform 19. The ends of the rope 11 are fixed on the four eye screws 20 in a cross shape. One end of the first connecting rod 21 is connected to the screw nut platform 19, and the other end is connected to the second connecting rod 22. The other end of the second connecting rod 22 is connected to the clamping jaw 25, and the middle section is connected to the sleeve platform 24. The clamping jaw 25 is connected to the sleeve platform 24 through the third connecting rod 23. A flange bearing 26 is installed at the connection of each platform or connecting rod, and an axle pin 27 is inserted in the middle. The rope 11 is tightened to keep the screw nut 18 from rotating in the direction of the screw 17 axis, and the screw 17 is driven to rotate by the screw motor 12, so that the screw nut platform 19 rises and falls on the screw 17 along with the screw nut 18. The rise of the screw nut platform 19 can pull the second connecting rod 22 through the first connecting rod 21, and the lower part of the second connecting rod 22 is retracted inward, and the movement of the third connecting rod 23 is parallel to the lower part of the second connecting rod 22. The two connecting rods drive the clamping jaws 25 to close together, and vice versa, the clamping jaws 25 open.

[0036] like Figure 3 and Figure 7 As shown, the clamping jaw rotating mechanism includes a sleeve 28, a terminal thrust bearing 29, a deep groove ball bearing 30, and a locking nut 31. The sleeve 28, the sleeve platform 24, the terminal thrust bearing 29, and the deep groove ball bearing 30 are sequentially inserted into the shoulder of the screw 17, and the locking nut 31 is fixed to the end of the screw 17 and abuts against the inner ring of the deep groove ball bearing 30. The rope 11 drives the screw nut platform 19 to rotate, and drives the sleeve platform 24 to rotate through the first connecting rod 21 and the second connecting rod 22, and the clamping jaw 25 also rotates accordingly. The terminal thrust bearing 29 bears the axial load, and the deep groove ball bearing 30 bears the radial load.

[0037] Working principle:

[0038] Gripper swing: Figure 4 As shown, the four sets of motor drums transmit torque to the screw nut platform 19 through the ropes 11 wound on the drums. The first motor drum 1 and the second motor drum 2 collect the rope, and the third motor drum 3 and the fourth motor drum 4 deliver the rope. The combined force acting on the screw nut platform 19 is forward, and the clamping jaw 25 swings forward, otherwise it swings backward. The first motor drum 1 and the fourth motor drum 4 collect the rope, and the second motor drum 2 and the third motor drum 3 deliver the rope. The combined force acting on the screw nut platform 19 is left, and the clamping jaw 25 swings left, otherwise it swings right.

[0039] Gripper opening and closing: Figure 5 , Figure 6As shown, the motor drum does not move, the rope 11 is tightened to keep the screw nut 18 from rotating in the direction of the screw 17 axis, and the screw 17 is driven to rotate by the screw motor 12, so that the screw nut platform 19 rises and falls on the screw 17 along with the screw nut 18. When the screw nut platform 19 rises, the connecting rod drives the clamping jaw 25 to close, so that the object is clamped. When the screw nut platform 19 falls, the connecting rod drives the clamping jaw 25 to open, so that the object is put down, or the outer side of the clamping jaw 25 is used to clamp the object with an inner concave surface.

[0040] Gripper rotation: Figure 7 As shown, the first motor drum 1 and the third motor drum 3 are used to collect the rope, and the second motor drum 2 and the fourth motor drum 4 are used to deliver the rope, which exerts a counterclockwise rotation torque on the screw nut platform 19, and vice versa.

[0041] The above is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several changes and substitutions without departing from the principle of the present invention. These changes and substitutions should also be regarded as the protection scope of the present invention.

Claims

1. A four-degree-of-freedom robot end effector driven by a parallel rope and a lead screw, characterized in that: It includes a rope driving mechanism, a screw motor fixing mechanism, a clamping claw mechanism and a clamping claw rotating mechanism; The rope drive mechanism comprises a first motor drum (1), a second motor drum (2), a third motor drum (3), a fourth motor drum (4), a positioning plate (5), a motor base (6), an anti-jumping device (7), a universal guide wheel (9), and a rope (11); the first motor drum (1), the second motor drum (2), the third motor drum (3), and the fourth motor drum (4) are fixed to the positioning plate (5) via the motor base (6); the anti-jumping device (7) is fixed to the positioning plate (5); the cross section of the motor drum is tangent to the cross section of the rope groove of the anti-jumping device (7); the universal guide wheel (9) is fixed to the bottom surface of the positioning plate (5); the starting end of the rope (11) is fixed to the bottom of the drum shaft of the first motor drum (1), the second motor drum (2), the third motor drum (3), and the fourth motor drum (4), and is led out after winding around the drum shaft, bypassing the rope groove of the anti-jumping device (7) and passing downward through the universal guide wheel (9); The screw motor fixing mechanism comprises a screw motor (12), a screw motor base (13), a thrust bearing (14), a reducer (15), a universal joint (16) and a screw (17); the screw motor (12) is fixed to the bottom surface of the positioning plate (5) through the screw motor base (13); the thrust bearing (14) is installed at the output end of the screw motor (12); one end of the reducer (15) is connected to the output shaft of the screw motor (12), the other end of the reducer (15) is inserted into the universal joint (16), and the other end of the universal joint (16) is connected to the screw (17); The clamping mechanism comprises a screw nut (18), a screw nut platform (19), a lifting eye screw (20), a first connecting rod (21), a second connecting rod (22), a third connecting rod (23), a shaft sleeve platform (24), and a clamping claw (25); the screw nut (18) is mounted on the screw (17), the screw nut platform (19) is fixed on the screw nut (18); the lifting eye screw (20) is symmetrically fixed on the four corners of the screw nut platform (19); the end of the rope (11) is fixed on the lifting eye screw (20); one end of the first connecting rod (21) is connected to the screw nut platform (19), the other end of the first connecting rod (21) is connected to the second connecting rod (22), the other end of the second connecting rod (22) is connected to the clamping claw (25), the middle section of the second connecting rod (22) is connected to the shaft sleeve platform (24), and the clamping claw (25) is connected to the shaft sleeve platform (24) through the third connecting rod (23).

2. The four-degree-of-freedom robot end effector driven by a hybrid parallel rope and lead screw according to claim 1, characterized in that: The anti-jump wire device (7) and the positioning plate (5) are fixed via an anti-jump wire device bracket (8); and the universal guide wheel (9) and the positioning plate (5) are fixed via a universal guide wheel bracket (10).

3. The four-degree-of-freedom robot end effector driven by a hybrid parallel rope and lead screw according to claim 1, characterized in that: A flange bearing (26) is installed at the connection point of the platform or the connecting rod, and an axle pin (27) is inserted in the middle of the flange bearing (26).

4. The four-degree-of-freedom robot end effector driven by a hybrid parallel cable and lead screw according to claim 1, characterized in that: The clamping jaw rotating mechanism comprises a sleeve (28), a terminal thrust bearing (29), a deep groove ball bearing (30) and a locking nut (31); the sleeve (28), the shaft sleeve platform (24), the terminal thrust bearing (29) and the deep groove ball bearing (30) are sequentially inserted into the screw rod (17); the locking nut (31) is fixed to the end of the screw rod (17) and abuts against the inner ring of the deep groove ball bearing (30).

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