A two-degree-of-freedom cable-driven differential mechanism

Abstract

The present invention discloses a two-degree-of-freedom rope-driven differential mechanism, comprising a mounting seat, a pair of driving wheels being controlled on the mounting seat, a cross shaft being rotatably provided at the end of the mounting seat, guide wheels being rotatably provided at both sides of the cross shaft, an output frame and an output wheel being rotatably provided at the upper and lower ends of the cross shaft, respectively, and the output frame and the output wheel being fixedly connected; the driving wheel, the guide wheel and the output wheel are all provided with inner and outer layers of wire grooves. The present invention discloses a two-degree-of-freedom rope-driven differential mechanism, compared with a traditional rope-driven differential mechanism, the transmission rope of the present invention is fixed to the driving wheel, and no relative sliding occurs between the wheel and the wire, so the transmission accuracy and transmission efficiency are high; the present invention connects the guide wheel and the output wheel by a cross shaft, so that the pitch and roll axes of the mechanism intersect at one point, thereby simplifying the spatial solution difficulty of a multi-degree-of-freedom serial robot, and greatly reducing the time and difficulty of planning and optimizing the robot's motion trajectory.

Description

Technical Field

[0001] The invention relates to the technical field of robot joints, and in particular to a two-degree-of-freedom cable transmission differential mechanism. Background Art

[0002] With the continuous development of the robotics industry, robots with more and more complex configurations have been born. Many work scenarios require two-degree-of-freedom joints with rotating axes crossing at one point. The two-degree-of-freedom differential gear train is a typical structure. Conventional differential gear trains use bevel gear transmission and two-degree-of-freedom differential structures based on rope-driven wire wheels. Compared with the bevel gear differential structure, the rope-driven differential structure has the characteristics of high transmission accuracy and is suitable for high-precision transmission scenarios. However, it currently still has problems such as complex multi-level structure of wire wheels, poor reliability of interference and crossing of transmission ropes, and large space occupation. Summary of the invention

[0003] The object of the present invention is to provide a two-degree-of-freedom cable drive differential mechanism to overcome the deficiencies in the prior art.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] The present invention discloses a two-degree-of-freedom rope transmission differential mechanism, comprising a mounting seat, a pair of driving wheels being controlled on the mounting seat, a cross shaft being rotatably provided at the end of the mounting seat, guide wheels being rotatably provided at both sides of the cross shaft, an output frame and an output wheel being rotatably provided at the upper and lower ends of the cross shaft, respectively, and the output frame and the output wheel being fixedly connected; the driving wheel, the guide wheel and the output wheel are all provided with inner and outer layers of wire grooves, a first transmission rope and a second transmission rope being fixed at both ends on the driving wheel are wound around the wire grooves of the driving wheel, the guide wheel and the output wheel; the axis of the driving wheel is parallel to the axis of the guide wheel; the radii of the inner and outer wire grooves on the driving wheel, the guide wheel and the output wheel satisfy: the ratio of the radii of the inner and outer wire grooves of the driving wheel is equal to the ratio of the radii of the inner and outer wire grooves of the guide wheel is equal to the ratio of the radii of the inner and outer wire grooves of the output wheel.

[0006] A driver for driving the driving wheel to rotate is fixedly provided on the mounting seat, the cross shaft is rotatably connected to the guide wheel via a horizontal axis, the cross shaft is rotatably connected to the output frame and the output wheel via a vertical axis, and a pair of guide wheels are symmetrically arranged on the cross shaft.

[0007] The inner and outer grooves of the driving wheel and the guide wheel on the same side are in the same plane, the planes where the inner and outer grooves of the guide wheel and the output wheel are located are perpendicular, and the edges of the inner and outer grooves of the guide wheel and the output wheel are tangent respectively.

[0008] Locking points are provided on both the inner and outer wire grooves on the driving wheel, and two locking points are arranged at the high end and the low end of the driving wheel respectively. The locking points fix the first transmission rope and the second transmission rope to the driving wheel by screws.

[0009] The first transmission rope starts from the locking point at the lower end of the driving wheel, passes through the high end of the driving wheel, goes around the lower end of the guide wheel, then passes through the rear side of the output wheel, goes around the guide wheel on the other side, and goes out from the lower end of the guide wheel on the other side, and finally goes around the high end of the driving wheel on the other side and is fixed to the locking point on the lower side of the driving wheel on the other side; the two second transmission ropes respectively start from the locking points at the high end of the driving wheels on both sides, go around the high end of the guide wheel through the lower end of the driving wheel, and then go around to the front side of the output wheel and are connected to the upper end surface of the output frame.

[0010] A tensioning device is fixedly mounted on the upper end surface of the output frame, and both ends of the second transmission rope are tightened by the tensioning device.

[0011] The output wheel is installed with fixing bolts, and the output wheel and the output frame are fixed by fixing bolts.

[0012] The first transmission rope and the second transmission rope are steel wire ropes or polyethylene fiber ropes.

[0013] The driver is a reduction motor, and the model is an N20 inverted reduction motor.

[0014] Beneficial effects of the present invention: The present invention is a two-degree-of-freedom rope-driven differential mechanism. Compared with the traditional rope-driven differential mechanism, the transmission rope of the present invention is fixed to the driving wheel, and no relative sliding occurs between the wheel and the wire, so the transmission accuracy and efficiency are high; the present invention connects the guide wheel and the output wheel through a cross axis, so that the pitch and roll axes of the mechanism intersect at one point, which simplifies the spatial solution difficulty of the multi-degree-of-freedom serial robot and greatly reduces the time and difficulty of robot motion trajectory planning and optimization; the present invention provides two layers of wire grooves on the wheel train, and the use of wire grooves can simplify the structure, so that the present invention has the advantages of compact structure, no cross interference and no relative sliding between the transmission ropes. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic structural diagram of an embodiment of the present invention;

[0016] Figure 2 This is a schematic diagram of the internal structure of the cross axis of an embodiment of the present invention;

[0017] Figure 3 This is a schematic diagram of the disassembled structure of parts in an embodiment of the present invention;

[0018] Figure 4 Embodiment of the present invention Figure 3A top view of

[0019] In the figure: 10—mounting seat, 11—driving wheel, 12—cross shaft, 13—guide wheel, 14—output frame, 15—output wheel, 16—driver, 17—first transmission rope, 18—second transmission rope, 19—tensioning device, 20—fixing bolt;

[0020] 1-0—driving ring inner and outer wire grooves, 1-01—driving ring inner wire grooves, 1-02—driving ring outer wire grooves, 2-0—guiding ring inner and outer wire grooves, 2-01—guiding ring inner wire grooves, 2-02—guiding ring outer wire grooves, 3-0—output ring inner and outer wire grooves, 3-01—output ring inner wire grooves, 3-02—output ring outer wire grooves. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below through the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the scope of the present invention. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0022] like Figure 1-4 As shown, a two-degree-of-freedom cable drive differential mechanism of this embodiment includes a driving wheel 11, a cross shaft 12, a guide wheel 13, an output wheel 15, an output frame 14 and a mounting seat 10;

[0023] A driving wheel 11 and a guide wheel 13 that can rotate along their respective axes are arranged on both sides of the mounting seat 10, a cross shaft 12 is rotatably arranged at the end of the mounting seat 10, and guide wheels 13 are rotatably arranged on both sides of the cross shaft 12. An output wheel 15 that can rotate along its own axis is arranged on the mounting seat 10, and the two guide wheels 13 are coaxially arranged in a mirror image, and the axes of the guide wheel 13 and the two driving wheels 11 are parallel, and the axes of the output wheel 15 and the two guide wheels 13 are located in the same plane and intersect vertically, and the output frame 14 is fixed on the output wheel 15 and can move synchronously, and the driving wheel 11 is driven by a driver 16 arranged on the mounting seat 10;

[0024] A first transmission rope 17 having both ends fixed to the two driving wheels 11 for transmitting power is wound around the two guide wheels 13, the two driving wheels 11 and the output wheel 15. A second transmission rope 18 having one end fixed to the output frame 14 and the other end fixed to the driving wheel 11 for transmitting power is wound around the output wheel 15 and the driving wheel 11 and the guide wheel 13 arranged on the same side. The second transmission rope 18 may not be fixed to the output frame 14, but the two ends are butt-jointed together to form a transmission rope. The first transmission rope 17 and the second transmission rope 18 on the same side are arranged in an "8" shape to transmit and drive the output wheel 15 to rotate on its own and around the axis of the guide wheel 13.

[0025] The guide wheel 13 provided in this embodiment has the function of changing the movement direction of the transmission rope. The output wheel 15 is the torque output end of the mechanism, which is connected to the extended output frame, and the two move synchronously. Through the first transmission rope 17 and the second transmission rope 18 arranged in an "8" shape on both sides, the output direction of the two driving wheels 11 is controlled by the motor, and the friction between the transmission rope and the wheel is relied on to realize power transmission to drive the output wheel to rotate and rotate around the axis of the guide wheel. Preferably, the two driving wheels 11 are arranged in an upper and lower staggered manner. In this way, the axis centers of the two driving wheels 11 may not overlap. The upper and lower staggered arrangement has a compact structure and greatly reduces the occupied space.

[0026] like Figure 4 As shown, the guide wheel 13 is provided with a guide annular inner and outer groove 2-0, the drive wheel 11 is provided with a drive annular inner and outer groove 1-0, and the output wheel 15 is provided with an output annular inner and outer groove 3-0. The guide annular inner and outer groove 2-0 and the drive annular inner and outer groove 1-0 on the same side are respectively located in the same plane, and the edges of the guide annular inner and outer groove 2-0 and the output annular inner and outer groove 3-0 are respectively tangent, and the planes where the guide annular inner and outer groove 2-0 and the output annular inner and outer groove 3-0 are located are perpendicular;

[0027] The second transmission rope 18 is respectively wound around the driving annular inner groove 1-01 and the guide annular inner groove 2-01 on the corresponding side, and then fixed on the output frame 14 after passing through the output annular inner groove 3-01. In addition, the first transmission rope 17 is wound around the two driving annular outer grooves 1-02, the two guide annular outer grooves 2-02 and the output annular outer groove 3-02 to transmit power to drive the output wheel 15 to rotate on itself and rotate along the axis of the guide wheel 13. The first transmission rope 17 and the second transmission rope 18 are installed in the corresponding inner and outer grooves and can be interchangeable.

[0028] In this arrangement, under the driving force, by means of friction between the rope and the wheel, the first transmission rope 17 and the second transmission rope 18 are used to transmit power and are not responsible for motion output. In addition, the rope winding radius of the driving wheel 11, the guide wheel 13 and the output wheel 15 should meet the following requirements:

[0029]

[0030] That is, the inner and outer groove radii on the driving wheel 11, the guide wheel 13 and the output wheel 15 satisfy: the inner and outer groove radii ratio of the driving wheel 11 is equal to the inner and outer groove radii ratio of the guide wheel 13 is equal to the inner and outer groove radii ratio of the output wheel 15.

[0031] In order to achieve reliable transmission of the first transmission rope 17 and the second transmission rope 18, the first transmission rope 17 has a locking point on each of the two driving wheels 11, and the locking point is arranged at the lower end of the driving wheel 11, and is used to fix the first transmission rope 17 relative to the driving wheel 11, and is tightened with screws in this example; the second transmission rope 18 has a locking point on each of the two driving wheels 11, and the locking point is arranged at the high end of the driving wheel 11, and is fixed relative to the driving wheel 11, and is tightened with screws in this example. At the same time, a tensioning device 19 is installed on the output frame for tensioning the second transmission rope 18.

[0032] The specific winding method of the first transmission rope 17 is as follows: the two ends of the first transmission rope 17 are respectively fixed at the lower ends of the two driving annular outer wire grooves 1-02, the transmission rope 17 is wound on the driving annular outer wire groove 1-02 from bottom to top, led downward to the lower end of the guide annular outer wire groove 2-02, and wound on the guide annular outer wire groove 2-02 from bottom to top, and then wound in the output annular outer wire groove 3-02;

[0033] The specific winding method of the second transmission rope 18 is as follows: one end of a second transmission rope 18 is fixed to the high end of the driving annular inner wire groove 1-01 on one side, and the transmission rope 7 is wound from top to bottom on the driving annular inner wire groove 1-01 on the one side, and is led upward to the guide annular inner wire groove 2-01 and the output ring inner wire groove 3-01, and the other end is led out and fixed on the output frame 14; one end of another second transmission rope 18 is fixed to the high end of the driving annular inner wire groove 1-01 on the other side, and the second transmission rope 18 is wound from top to bottom on the driving annular inner wire groove 1-01 on the other side, and is led upward to the guide annular inner wire groove 2-01 and the output annular inner wire groove 3-01, and the other end is led out and fixed on the output frame 14.

[0034] When the two driving wheels 11 move in the same direction, the output frame 14 rotates along the axis of the horizontal axis 121 on the cross shaft 12 through the transmission of the guide wheel 13, the first transmission rope 17 and the second transmission rope 18; when the two driving wheels 11 move in the opposite direction, the output frame 14 swings left and right along the axis of the vertical axis 122 on the cross shaft 12 through the transmission of the guide wheel 13, the first transmission rope 17 and the second transmission rope 18. Through the combined effect of these two processes, the output frame 14 can move with two degrees of freedom, and the two axes of the guide wheel 13 and the output wheel 15 are also the rotation axes of the two degrees of freedom of the joint.

[0035] The transmission rope 7 is a steel wire rope or a polyethylene fiber line, or a fiber line of a certain strength made of other polymer materials, which can all play the role of a transmission rope.

[0036] In order to facilitate assembly and use, the output wheel 15 and the guide wheel 13 are connected through a cross shaft 12, and the cross shaft 12 is rotatably connected to the guide wheel 13 through a horizontal shaft 121. A pair of guide wheels 13 are symmetrically arranged on the cross shaft 12, and the output frame 14 is rotatably connected to the bottom end of the vertical shaft 122. The output wheel 15 is rotatably arranged at the top end of the vertical shaft 122, and the upper end surface of the output frame 14 is fixedly connected to the output wheel 15 through a fixing bolt 20. In this way, in the process of realizing the up-and-down rotation of the output wheel 15 and the output frame 14 around the axis of the guide wheel 13, the output wheel 15 and the output frame 14 can also rotate around the axis of the output wheel 15. The up-and-down rotation and left-and-right yaw of the output wheel 15 do not interfere with each other, and the output of two degrees of freedom is better realized.

[0037] In order to ensure sufficient output torque, the driver 16 of this embodiment is a reduction motor, such as an N20 flip-down reduction motor. With this configuration, the output driving torque is relatively large, which can meet the requirements of driving the output wheel 15 and the output frame 14 through the drive of the transmission rope 7 to achieve two-degree-of-freedom motion output.

[0038] The same-direction and opposite-direction rotation of the two driving wheels 11 in the embodiment of the present invention will drive the pitch and yaw motion of the output wheel 15 . By combining the two driving wheels 11 with different steering speeds, the output end can achieve controllable motion in two degrees of freedom.

[0039] The present invention has been disclosed as above with preferred implementation cases, but it is not used to limit the present invention. Any technician familiar with the profession can make slight changes or modifications to equivalent implementation cases with equivalent changes by using the above-disclosed structures and technical contents without departing from the scope of the technical solution of the present invention, which still fall within the scope of the technical solution of the present invention.

Claims

1. A two-degree-of-freedom cable drive differential mechanism, characterized in that: The invention comprises a mounting seat (10), wherein a pair of driving wheels (11) are controlled to be arranged on the mounting seat (10), a cross shaft (12) is rotatably arranged at the end of the mounting seat (10), guide wheels (13) are rotatably arranged on both sides of the cross shaft (12), an output frame (14) and an output wheel (15) are rotatably arranged at the upper and lower ends of the cross shaft (12), and the output frame (14) and the output wheel (15) are fixedly connected; the driving wheel (11), the guide wheel (13) and the output wheel (15) are all provided with inner and outer wire grooves, and the driving wheel (11), the guide wheel (13) and the output wheel (15) are provided with inner and outer wire grooves, and the driving wheel (11) and the guide wheel (13 ... A first transmission rope (17) and a second transmission rope (18) are wound around the wire grooves of the drive wheel (11), the guide wheel (13) and the output wheel (15), both ends of which are fixed on the drive wheel (11); the axis of the drive wheel (11) is parallel to the axis of the guide wheel (13); and the radii of the inner and outer wire grooves on the drive wheel (11), the guide wheel (13) and the output wheel (15) satisfy the following conditions: the ratio of the inner and outer wire groove radii of the drive wheel (11) is equal to the ratio of the inner and outer wire groove radii of the guide wheel (13) is equal to the ratio of the inner and outer wire groove radii of the output wheel (15); The inner and outer wire grooves on the driving wheel (11) are both provided with locking points, and the two locking points are respectively arranged at the high end and the low end of the driving wheel (11), and the locking points fix the first transmission rope (17) and the second transmission rope (18) to the driving wheel (11) by means of screws; The first transmission rope (17) starts from the locking point at the lower end of the driving wheel (11), passes through the high end of the driving wheel (11) and goes around the lower end of the guide wheel (13), then passes through the rear side of the output wheel (15) and goes around the guide wheel (13) on the other side and goes out from the lower end of the guide wheel (13) on the other side, and finally goes around the high end of the driving wheel (11) on the other side and is fixed to the locking point at the lower side of the driving wheel (11) on the other side; the two second transmission ropes (18) start from the locking points at the high ends of the driving wheels (11) on both sides, pass through the low end of the driving wheel (11) and go around the high end of the guide wheel (13), then go around to the front side of the output wheel (15) and are connected to the upper end surface of the output frame (14).

2. A two-degree-of-freedom cable drive differential mechanism according to claim 1, characterized in that: A driver (16) for driving the driving wheel (11) to rotate is fixedly provided on the mounting seat (10); the cross shaft (12) is rotatably connected to the guide wheel (13) via a horizontal shaft (121); the cross shaft (12) is rotatably connected to the output frame (14) and the output wheel (15) via a vertical shaft (122); and a pair of guide wheels (13) are symmetrically arranged on the cross shaft (12).

3. A two-degree-of-freedom cable drive differential mechanism according to claim 1, characterized in that: The inner and outer grooves of the driving wheel (11) and the guide wheel (13) on the same side are in the same plane, the planes where the inner and outer grooves of the guide wheel (13) and the output wheel (15) are located are perpendicular, and the edges of the inner and outer grooves of the guide wheel (13) and the output wheel (15) are tangent to each other.

4. A two-degree-of-freedom cable drive differential mechanism according to claim 1, characterized in that: A tensioning device (19) is fixedly mounted on the upper end surface of the output frame (14), and both ends of the second transmission rope (18) are tensioned by the tensioning device (19).

5. A two-degree-of-freedom cable drive differential mechanism according to claim 1, characterized in that: A fixing bolt (20) is installed on the output wheel (15), and the output wheel (15) and the output frame (14) are fixed by the fixing bolt (20).

6. A two-degree-of-freedom cable drive differential mechanism according to claim 1, characterized in that: The first transmission rope (17) and the second transmission rope (18) are steel wire ropes or polyethylene fiber ropes.

7. A two-degree-of-freedom cable drive differential mechanism according to claim 1, characterized in that: The driver (16) is a reduction motor, and its model is an N20 inverted reduction motor.

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