A six-degree-of-freedom rope-driven parallel robot

Abstract

This invention discloses a six-degree-of-freedom (DOF) rope-driven parallel robot, comprising a static platform, a moving platform, and three sets of identical two-DOF planar rope-driven parallel branches. Each set of two-DOF planar rope-driven parallel branches includes a movable mechanism and a driving mechanism. The movable mechanism consists of a support plate, a central rotating shaft, a linear slide rail, a slider, and upper and lower anchor supports; the driving mechanism consists of a servo motor, a winding drum, a driving rope, and a tension spring. The three sets of two-DOF planar rope-driven parallel branches are rotatably connected to the static platform and simultaneously hinged to the moving platform via ball joints. The three sets of two-DOF planar rope-driven parallel branches are evenly distributed at 120 degrees in the circumferential direction and jointly support and drive the moving platform to achieve six-DOF spatial motion. This invention overcomes the limitation of traditional rope-driven robots being unable to withstand pressure and has advantages such as adaptive posture adjustment, good high-speed dynamic response performance, no occupation of workspace, and easy control, and has broad application prospects.

Description

Technical Field

[0001] This invention relates to the field of parallel robot technology, and in particular to a six-degree-of-freedom rope-driven parallel robot based on a two-degree-of-freedom planar rope-driven parallel mechanism. Background Technology

[0002] Parallel robots, due to their advantages such as high structural rigidity and strong load-bearing capacity, have been widely used in fields such as industrial grasping, precision positioning, and medical rehabilitation. Among them, rope-driven parallel robots utilize flexible ropes to replace rigid rods, and have significant advantages such as large workspace, low cost, and high load-to-weight ratio.

[0003] However, due to the typical unidirectional mechanical property of ropes—they can only withstand tension and not compression—traditional rope-driven robots typically rely on gravity to maintain rope tension. In this design, when the moving platform performs high-speed pose changes, the platform is susceptible to excessive displacement due to inertia or external forces, making it difficult to meet the dynamic response performance and positioning accuracy requirements of high-frequency operations. To overcome this deficiency, existing technologies often achieve tension by arranging redundant ropes under the moving platform. However, such designs occupy a large amount of usable working space under the moving platform, greatly limiting the robot's application flexibility. Furthermore, the nonlinear fluctuations in rope length and tension under different poses of the moving platform also pose challenges to dynamic modeling and precise control.

[0004] In conclusion, developing a rope-driven parallel robot that can achieve high-speed dynamic response without occupying the working space of the moving platform has significant practical value and broad application prospects. Summary of the Invention

[0005] To address the aforementioned limitations of existing technologies, this invention provides a six-degree-of-freedom (DOF) rope-driven parallel robot. This robot boasts advantages such as high-speed dynamic response, minimal space occupation on the moving platform, simple and compact structure, and a high load-to-weight ratio. By integrating drive and spring tensioning mechanisms within the branches, this six-DOF rope-driven parallel robot achieves high-speed and stable operation of the moving platform without encroaching on workspace, meeting users' higher requirements for rope-driven parallel robots and demonstrating broad application prospects.

[0006] To solve the above-mentioned technical problems, the present invention proposes a six-degree-of-freedom rope-driven parallel robot, which includes a static platform, a moving platform, and three sets of two-degree-of-freedom planar rope-driven parallel branches with the same structure.

[0007] The two-degree-of-freedom planar rope-driven parallel chain includes a movable mechanism and a driving mechanism. The movable mechanism consists of a support plate, a central rotating shaft, a linear slide rail, a slider, an upper anchor support, and a lower anchor support. The central rotating shaft is rotatably connected to the support plate. The slider is fixedly installed on the central rotating shaft. The linear slide rail is slidably connected to the slider. Both ends of the linear slide rail are fixedly connected to the upper anchor support and the lower anchor support, respectively. The driving mechanism includes two sets of symmetrically arranged rope driving mechanisms with identical structures. Each rope driving mechanism includes a servo motor, a winding drum, a driving rope, and a tension spring. The servo motor is fixedly installed on the support plate in the movable mechanism. The winding drum is fixedly installed on the output shaft of the servo motor. The middle part of the driving rope is wound around the winding drum. One end of the driving rope is hooked to the lower anchor support in the movable mechanism, and the other end of the driving rope is hooked to one end of the tension spring. The other end of the tension spring is hooked to the upper anchor support in the movable mechanism.

[0008] Three sets of two-degree-of-freedom planar rope-driven parallel branches are rotatably connected to the static platform and simultaneously hinged to the moving platform; the three sets of two-degree-of-freedom planar rope-driven parallel branches are evenly distributed at 120 degrees in the circumferential direction, and together support and drive the moving platform located at the projection position of the center of the circle to achieve six-degree-of-freedom spatial motion.

[0009] Furthermore, in the six-degree-of-freedom rope-driven parallel robot of the present invention:

[0010] The axis of the central rotating shaft is perpendicular to the surface of the support plate.

[0011] The static platform is fixedly provided with three sets of support chain brackets, and the moving platform is fixedly provided with three ball hinges; the support plates in the three sets of two-degree-of-freedom planar rope driven parallel chains are rotatably connected to the three sets of support chain brackets respectively, and the lower anchoring supports in the three sets of two-degree-of-freedom planar rope driven parallel chains are respectively connected to the three ball hinges.

[0012] Each drive rope is fixed to the winding drum at the middle via a rope knot; the lower anchor support is fixed to the ball hinge via a threaded connector; both the upper and lower anchor supports are provided with a hook structure for connecting to the drive rope and the tension spring.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0014] (1) The present invention solves the limitation that flexible ropes in traditional rope-driven robots cannot be compressed by coupling the rigid support of the slide rail consisting of linear slide rail and slider with the rope tensioning system consisting of drive rope and tension spring, and significantly improves the dynamic response stability of the moving platform under high-speed movement.

[0015] (2) The present invention integrates the drive mechanism and the tension spring on the two-degree-of-freedom planar rope drive parallel branch, eliminating the need for redundant tension ropes to be arranged under the moving platform as in traditional mechanisms, thus not occupying the working space under the moving platform and greatly expanding the application scenarios of the robot.

[0016] (3) The present invention utilizes the triangular geometric layout formed by the rope exit point of the winding drum, the central rotating shaft and the anchor points at both ends of the slide rail. Based on the principle that the sum of the rope lengths on both sides is approximately constant, it achieves an approximately constant tension pressure, which improves the accuracy of dynamic modeling and is beneficial to the motion control precision of the robot.

[0017] (4) Due to the combined action of the drive mechanism and the moving mechanism of the present invention, the moving platform can automatically adjust its posture according to the changes in the drive angle and external force, and the present invention has the characteristic of self-adaptation.

[0018] (5) The drive mechanism of the present invention can flexibly adjust the elongation of the rope by rotating the servo motor, thereby adjusting the tension of the tension spring to adapt to different load requirements.

[0019] (6) The slider, linear guide rail and ball joint in this invention are modular components, which can replace the traditional integrated complex components, effectively reduce manufacturing costs, improve positioning accuracy, optimize the stress state of components, and significantly reduce joint size. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the six-degree-of-freedom rope-driven parallel robot of the present invention;

[0021] Figure 2 for Figure 1 The diagram shows a set of two-degree-of-freedom planar rope-driven parallel branches.

[0022] Figure 3 yes Figure 2 The image shows another perspective view of a two-degree-of-freedom planar rope-driven parallel branch chain.

[0023] In the diagram: 1-Static platform, 11-Branch support, 2-Moving mechanism, 21-Support plate, 22-Central pivot, 23-Linear slide rail, 24-Slider, 25-Upper anchor support, 26-Lower anchor support, 3-Drive mechanism, 31-Servo motor, 32-Winding drum, 33-Drive rope, 34-Tension spring, 4-Two-degree-of-freedom planar rope drive parallel branch, 5-Moving platform, 51-Spherical hinge. Detailed Implementation

[0024] The design concept of a six-degree-of-freedom rope-driven parallel robot proposed in this invention is as follows: The robot mainly includes a static platform, a moving platform, and three sets of identical two-degree-of-freedom planar rope-driven parallel branches. To significantly improve the robot's high-speed dynamic response performance, this invention introduces tension springs into the branch drive links. The combination of the elastic tension provided by the springs and the rigid components of the slide rails ensures that the ropes are always under tension during high-speed movement, effectively solving the dynamic instability problem caused by unidirectional force on the ropes. To free up the working space below the moving platform, this invention cleverly integrates the tension springs and the drive mechanism inside the branches, thereby avoiding the interference of redundant tension ropes on the bottom working space in traditional rope-driven robots, greatly improving the operational flexibility of the mechanism. Regarding the stability of the tension force, this invention cleverly utilizes the geometric compensation principle between the rope exit point of the winding drum, the central rotating shaft, and the anchor points at both ends of the linear slide rail, making the deformation change of the tension springs during the movement of the mechanism extremely small, thus achieving an approximately constant tension force output. This characteristic significantly reduces the nonlinearity of the dynamic modeling. Furthermore, this invention employs a modular component assembly design to replace traditional integrated complex components, achieving lightweighting, reducing motion inertia, effectively optimizing stress conditions, and reducing overall size while achieving similar benefits. These combined structures enable the parallel robot to exhibit numerous advantages, including excellent dynamic response performance, high space utilization, stable tension, and a simple and compact structure.

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the following embodiments are by no means intended to limit the present invention.

[0026] like Figure 1 and Figure 2 As shown, this invention provides a six-degree-of-freedom rope-driven parallel robot, including a static platform 1, a moving platform 5, and three sets of identical two-degree-of-freedom planar rope-driven parallel support chains 4. The static platform 1 is a cubic frame structure built of aluminum profiles. Three sets of support chain brackets 11 are fixedly installed on the upper plane of the static platform 1. The moving platform 5 has three ball joints 51 on its edge, as shown... Figure 2 and Figure 3 As shown.

[0027] The two-degree-of-freedom planar rope-driven parallel branches 4 are mounted on the static platform 1 via the branch bracket 11. One end of each of the three sets of two-degree-of-freedom planar rope-driven parallel branches 4 is rotatably connected to the static platform 1, and the other end is hinged to the moving platform 5. The three sets of two-degree-of-freedom planar rope-driven parallel branches 4 are evenly distributed at 120 degrees in the circumferential direction and jointly support and drive the moving platform 5 located at the center projection position of the circumference to achieve six-degree-of-freedom spatial motion.

[0028] like Figure 2 and Figure 3As shown, each of the two-degree-of-freedom planar rope-driven parallel branches 4 includes a movable mechanism 2 and a driving mechanism 3.

[0029] The movable mechanism 2 consists of a support plate 21, a central rotating shaft 22, a linear slide rail 23, a slider 24, an upper anchoring support 25, and a lower anchoring support 26. The central rotating shaft 22 is rotatably connected to the support plate 21, and the axis of the central rotating shaft 22 is perpendicular to the surface of the support plate 21. The two sides of the support plate 21 are rotatably connected to rolling bearings in the holes of the support bracket 11 via rotating shafts, forming the first rotating pair of the support chain. The central rotating shaft 22 is rotatably connected to a flange bearing in the center hole of the support plate 21, forming the second rotating pair. The slider 24 is fixedly installed on the central rotating shaft 22 using bolts and nuts. The linear slide rail 23 is slidably connected to the slider 24, allowing the linear slide rail 23 to perform linear reciprocating motion in a direction perpendicular to the central rotating shaft 22. To improve the dynamic performance of the moving platform 5, the linear slide rail 23 and the slider 24 are selected with a focus on lightweight design, using high-strength lightweight aluminum alloy or carbon fiber composite materials, effectively reducing the moment of inertia of the support chain. The two ends of the linear slide rail 23 are fixedly connected to the upper anchor support 25 and the lower anchor support 26 respectively; both sides of the upper anchor support 25 and the lower anchor support 26 are perforated lug-type structures, providing anchoring points for the drive mechanism 3.

[0030] The drive mechanism 3 includes two sets of symmetrically arranged and structurally identical rope drive mechanisms. Each rope drive mechanism includes a servo motor 31, a winding drum 32, a drive rope 33, and a tension spring 34. The servo motor 31 is fixedly installed on both sides of the support plate 21 in the movable mechanism 2 by bolts. The winding drum 32 is fixedly connected to the pre-reserved threaded hole on the output shaft of the servo motor 31 by bolts. The winding drum 32 is designed as a hollow shaft structure, with multiple radial through holes that are axially aligned and evenly distributed. The drive rope 33 has a knot in the middle and is embedded inside the winding drum 32. Since the diameter of the knot is larger than the inner diameter of the hole on the winding drum 32, the drive rope 33 is fixedly connected to the winding drum 32. The two ends of the drive rope 33 pass through two radial through holes and wrap around the winding drum 32 several times in opposite directions. One end, after being tightened, is directly hooked into the lug through hole of the lower anchoring support 26 for fixation. The other end, after being tightened, is hooked into one end of the tension spring 34, while the other end of the tension spring 34 is hooked into the lug through hole of the upper anchoring support 26. By adjusting the drive angle of the servo motor 31, the linear displacement of the linear slide rail 23 and its combined motion with the rotation of the central shaft 22 can be controlled.

[0031] In this embodiment, the tension spring 34 is in a pre-tensioned state during assembly, and the tension it provides always points downward along the linear slide rail 23. Based on the principle of triangle geometry, in the triangle formed by the rope exit point of the winding drum 32, the center point of the central rotating shaft 22, and the anchor points at both ends of the linear slide rail 23, since the length of the base linear slide rail is constant and the sum of the rope lengths on both sides is approximately constant, the deformation of the tension spring 34 remains basically consistent in any pose during movement, thus the tension it provides remains approximately constant. This design gives the moving platform 5 a more accurate and stable tension, significantly reduces the nonlinearity of dynamic modeling, simplifies the difficulty of dynamic analysis of the six-degree-of-freedom rope-driven parallel robot, and also facilitates kinematic control. Furthermore, by adjusting the connection position between the drive rope 33 and the tension spring 34 or by replacing the spring with one of different stiffness, the tension can be flexibly adjusted to adapt to different load requirements.

[0032] like Figure 2 and Figure 3 As shown, in this invention, the support plates 21 of the three sets of two-degree-of-freedom planar rope-driven parallel branches 4 are rotatably connected to the three sets of branch supports 11, and the lower anchoring supports 26 of the three sets of two-degree-of-freedom planar rope-driven parallel branches 4 are connected to the three ball hinges 51, thereby realizing the connection between the three sets of two-degree-of-freedom planar rope-driven parallel branches 4 and the static platform 1 and the moving platform 5. The lower anchoring supports 26 are provided with threaded connection structures to cooperate with the installation of the ball hinges 51. The moving platform 5 adopts a hollow plate design, which minimizes its own weight by hollowing out a large area while ensuring sufficient structural rigidity, thereby improving the high-speed dynamic response performance of the end effector. In order to facilitate users to set sensors, mechanical grippers or other operating facilities at the end of the moving platform 5, multiple standard threaded holes are reserved on the moving platform 5. This invention uses modular components such as sliders, slide rails, and ball hinges to replace traditional integrated complex components, which not only reduces manufacturing costs but also significantly reduces joint size and optimizes stress conditions.

[0033] Although the present invention has been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many improvements and changes under the guidance of the present invention without departing from the spirit of the present invention, and these improvements and changes are all within the protection scope of the present invention.

Claims

1. A six-degree-of-freedom rope-driven parallel robot, comprising a static platform (1), a moving platform (5), and three sets of identical two-degree-of-freedom planar rope-driven parallel branches (4), wherein the two-degree-of-freedom planar rope-driven parallel branches (4) include a movable mechanism (2) and a driving mechanism (3); characterized in that, The movable mechanism (2) consists of a support plate (21), a central rotating shaft (22), a linear slide rail (23), a slider (24), an upper anchor support (25), and a lower anchor support (26); the central rotating shaft (22) is rotatably connected to the support plate (21); the slider (24) is fixedly installed on the central rotating shaft (22); the linear slide rail (23) is slidably connected to the slider (24); the two ends of the linear slide rail (23) are respectively fixedly connected to the upper anchor support (25) and the lower anchor support (26); The drive mechanism (3) includes two sets of symmetrically arranged and identical rope drive mechanisms. Each rope drive mechanism includes a servo motor (31), a winding drum (32), a drive rope (33), and a tension spring (34). The servo motor (31) is fixedly installed on the support plate (21) in the movable mechanism (2). The winding drum (32) is fixedly installed on the output shaft of the servo motor (31). The middle part of the drive rope (33) is wound around the winding drum (32). One end of the drive rope (33) is hooked to the lower anchor support (26) in the movable mechanism (2). The other end of the drive rope (33) is hooked to one end of the tension spring (34). The other end of the tension spring (34) is hooked to the upper anchor support (25) in the movable mechanism (2). Three sets of two-degree-of-freedom planar rope-driven parallel branches (4) are rotatably connected to the static platform (1) and hinged to the moving platform (5); the three sets of two-degree-of-freedom planar rope-driven parallel branches (4) are evenly distributed at 120 degrees in the circumferential direction and jointly support and drive the moving platform (5) located at the center projection position of the circumference to achieve six-degree-of-freedom spatial motion.

2. The six-degree-of-freedom rope-driven parallel robot according to claim 1, characterized in that, The axis of the central rotating shaft (22) is perpendicular to the surface of the support plate (21).

3. The six-degree-of-freedom rope-driven parallel robot according to claim 1, further characterized in that, The static platform (1) is fixedly provided with three sets of branch support brackets (11), and the moving platform (5) is fixedly provided with three ball hinges (51); the support plate (21) in the three sets of two-degree-of-freedom planar rope driven parallel branches (4) is rotatably connected to the three sets of branch support brackets (11), and the lower anchor support (26) in the three sets of two-degree-of-freedom planar rope driven parallel branches (4) is connected to the three ball hinges (51).

4. The six-degree-of-freedom rope-driven parallel robot according to claim 3, further characterized in that, Each of the drive ropes (33) is fixed to the winding drum (32) at the middle through a rope knot; the lower anchor support (26) is fixed to the ball hinge (51) through a threaded connector; both the upper anchor support (25) and the lower anchor support (26) are provided with a hook structure that connects to the drive rope (33) and the tension spring (34).

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