Mechanical arm cable servo device and control method thereof

Abstract

This invention relates to the field of robotic arms or robots, and provides a cable follower device and its control method for a robotic arm. The cable follower device for the robotic arm includes at least one cable fixing structure and a slip ring assembly. The slip ring assembly includes a slip ring, a slider, and a sliding ball. The slip ring is mounted on the robotic arm and has a groove. The slider slides by the sliding ball inserted into the groove. The slider has a first cable support, and the cable passes through the first cable support and the cable fixing structure. The cable attached to the robotic arm can follow the joint movements, improving the safety and stability of the robotic arm during movement.

Description

Technical Field

[0001] This invention relates to the field of robotic arms or robots, and in particular to a cable follower device for a robotic arm and its control method. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] In various environments where intelligent monitoring equipment is used, compared to fixed equipment placed at a fixed point, robotic arms have the characteristics of being able to extend, move in multiple directions and angles, and move flexibly. Many places have already applied intelligent monitoring equipment with robotic arms, especially mobile intelligent inspection robots. Generally, the end effector of robotic arms is integrated and assembled by the robotic arm manufacturer. The signal and power cables of the end effector are usually built into the robotic arm and are fixed products. They are easy to integrate and not prone to failure, but they have the characteristics of limited functionality and cannot be customized according to user requirements.

[0004] Therefore, users need to install devices at the end effector of the robotic arm that meet their specific requirements. Since these end effectors require signal transmission and power, it's generally impossible to route cables inside the arm due to limitations in cable thickness, core count, and shielding. Large movements of the robotic arm joints often necessitate slip ring routing for cable connections, which is impractical for user-customized end effectors. Therefore, in most cases, external cable routing is the only option, requiring the cables to be fixed to the side of the robotic arm. Typically, the stiffness and ductility of the cables affect the robotic arm's movement, necessitating sufficient slack between each clamping point to compensate for the arm's travel during movement. This is only feasible for small robotic arm movements. With large swings, especially during joint rotation, the cables attached to the arm will inevitably be dragged and pulled, hindering movement and potentially damaging cable supports, or even the robotic arm or cables themselves. Summary of the Invention

[0005] To address the technical problems mentioned above, this invention provides a cable follower device and its control method for a robotic arm. The cable attached to the robotic arm can follow the joint movement, improving the safety and stability of the robotic arm during movement.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The first aspect of the present invention provides a cable follower device for a robotic arm.

[0008] A cable follower device for a robotic arm includes: at least one cable fixing structure and a slip ring assembly disposed on the robotic arm. The slip ring assembly includes a slip ring, a slider and a sliding ball. The slip ring is mounted on the robotic arm and has a groove. The slider slides by the sliding ball inserted into the groove. The slider has a first cable support, and the cable passes through the first cable support and the cable fixing structure.

[0009] Furthermore, the slider is provided with a positioning screw at the corresponding position of the sliding ball to fix the sliding ball on the slider.

[0010] Furthermore, the cable fixing structure includes a steel strip, a cable bracket support, and a second cable bracket. The steel strip is sleeved on the robotic arm, the cable bracket support is used to fix the steel strip, and the second cable bracket is installed on the cable bracket support.

[0011] Furthermore, the second cable bracket is fixed to the cable bracket support by countersunk screws, and the cable passes through the second cable bracket.

[0012] Furthermore, the robotic arm includes robotic arm A-axis, robotic arm B-axis, robotic arm C-axis, robotic arm D-axis, and robotic arm E-axis connected to the end device by a robotic arm base.

[0013] Furthermore, the cable support bracket moves synchronously with the E-axis of the robotic arm end.

[0014] Furthermore, the slip ring is provided with grooves on its upper surface and both sides.

[0015] Furthermore, the slip ring includes a first slip ring and a second slip ring, which are fixed together by countersunk screws to form a slip ring.

[0016] Furthermore, one end of the cable is fixed to the end device, and the other end is fixed to the robotic arm base.

[0017] A second aspect of the present invention provides a method for controlling a cable follower device on a robotic arm.

[0018] A control method for a cable follower device on a robotic arm, applied to the cable follower device on a robotic arm as described in the first aspect, includes: relative rotation between the D-axis and E-axis of the robotic arm, and a cable connector on the E-axis of the robotic arm causing the slider of the cable on the D-axis of the robotic arm to twist to one side, so that the slider slides along the slide groove around the slip ring.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] The slip ring structure designed in this invention allows the slider to be positioned radially and axially in both directions on the slip ring, to rotate continuously on the slip ring, and to be installed in multiple sets, thus expanding the freedom of the cable. Furthermore, the slider moves circumferentially within the groove. This invention enables the cable fixing part to rotate synchronously with the cover joint during the rotation of a certain joint of the robotic arm. This ensures that the joint rotation is no longer hindered by the cable fixing, and the cable is not easily pulled by the joint. The two are no longer interdependent in their motion relationship, allowing the cable to move with the movement of the robotic arm joint.

[0021] This invention improves the safety of inspection robots equipped with robotic arms during operation, solves the problems of cable tangling and pulling caused by the application of robotic arms on inspection robots, and also solves the problem of ensuring the safe operation of robotic arms. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0023] Figure 1 This is a schematic diagram of the robotic arm inspection state functional module shown in this invention;

[0024] Figure 2 This is a schematic diagram of the robotic arm motion state functional module shown in this invention;

[0025] Figure 3 This is a schematic diagram illustrating the detailed assembly of the robotic arm according to the present invention;

[0026] Figure 4 This is a front view of the slip ring slider structure shown in this invention;

[0027] Figure 5 This is a cross-sectional view of the slip ring slider structure shown in this invention;

[0028] Figure 6 This is a front view of the cable fixing structure shown in this invention;

[0029] Figure 7 This is a cross-sectional view of the cable fixing structure shown in this invention;

[0030] The diagram shows: 1. Robotic arm assembly, 2. End device assembly, 3. Cable assembly, 4. Slip ring assembly, 5. Cable bracket assembly, 6. Robotic arm base, 7. Robotic arm A-axis, 8. Robotic arm B-axis, 9. Robotic arm C-axis, 10. Robotic arm D-axis, 11. Robotic arm E-axis, 12. Cable, 13. Cable bracket, 14. Steel strip, 15. First slip ring, 16. Second slip ring, 17. Slider, 18. Sliding ball, 19. Positioning screw, 20. Countersunk screw, 21. Slide groove, 22. Cable connector, 23. Cable bracket support. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0032] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0033] Example 1

[0034] like Figure 1 As shown, this embodiment provides a cable follower device for a robotic arm, including: a robotic arm assembly 1, an end effector assembly 2, a cable assembly 3, a slip ring assembly 4, a cable support assembly 5, a robotic arm base 6, a robotic arm A-axis 7, a robotic arm B-axis 8, a robotic arm C-axis 9, a robotic arm D-axis 10, a robotic arm E-axis 11, a cable 12, a cable support 13, a steel strip 14, a first slip ring 15, a second slip ring 16, a slider 17, a sliding ball 18, a positioning set screw 19, a countersunk screw 20, a groove 21, a cable connector 22, a cable support base 23, and fasteners.

[0035] like Figure 1 As shown, the overall structure consists of several functional areas of the robotic arm from top to bottom. The end effector assembly 2 is located at the far end of the robotic arm assembly 1 and is connected to the last robotic arm E-axis 11 via fasteners. The cable assembly 3 starts from the end effector, is attached to the robotic arm E-axis 11, robotic arm D-axis 10, and robotic arm C-axis 9, and then goes to the robotic arm A-axis 7, and enters the equipment inside where the robotic arm is installed, and enters the equipment control section.

[0036] like Figure 2 As shown, when the robotic arm assembly 1 extends, the cable assembly 3 moves in tandem with the robotic arm's movement. However, this is limited to the extension of the arm; the range of motion of the robotic arm joints is not large, and the extension is performed within a safe and prescribed range. When the robotic arm retracts, the cable assembly 3 should be able to return to its original position. Figure 1 The state shown.

[0037] like Figure 3As shown, the robotic arm assembly 1 consists of, from top to bottom, a robotic arm base 6, a robotic arm A-axis 7, a robotic arm B-axis 8, a robotic arm C-axis 9, a robotic arm D-axis 10, and a robotic arm E-axis 11 at the very end, which is connected to the end device assembly 2. The cable assembly 3 exits from the tail of the end device assembly 2. At this time, the cable support 23 and the robotic arm end E-axis 11 are moving synchronously. The cable support 13, which is fixed on the slider 17 on the slip ring assembly 4, crosses the joint between the robotic arm E-axis 11 and the robotic arm D-axis 10. Then, it passes through the cable support assembly 5 fixed on the robotic arm C-axis 9, and then through the cable support assembly 5 fixed on the robotic arm B-axis 8 before continuing to move upward until it enters the interior of the upper-level equipment.

[0038] The slip ring assembly 4 and the cable bracket assembly 5 will be discussed separately below:

[0039] Cable bracket assembly 5 is a fixed cable bracket, and its structure is as follows: Figure 6 , Figure 7 As shown, the system includes a steel strip 14, a cable bracket 23, and a cable bracket 13. The steel strip 14 surrounds a certain axis of the robotic arm and binds the cable bracket 23 to the axis. At the same time, the cable bracket 13 is fixed to the cable bracket 23 by countersunk screws 20. At this time, the cable 12 can be passed through the cable bracket 13 and fixed to a certain axis of the robotic arm, serving as a fixed point for the cable on the robotic arm.

[0040] For slip ring assembly 4, it is a sliding cable bracket, and its structure is as follows: Figure 4 , Figure 5 As shown, it includes a cable bracket 13, a first slip ring 15, a second slip ring 16, a slider 17, a sliding ball 18, a positioning set screw 19, a countersunk screw 20, and a groove 21, as follows. Figure 6 , Figure 7 As shown, the first slip ring 15 and the second slip ring 16 are each semi-circular, and the two are combined to form a complete circle. The joint has a concave-convex structure, forming a closely fitting structure, which ensures that the two slip rings are strictly positioned. The two ends are then horizontally fixed to form the entire slip ring by four countersunk screws 20. The sliding grooves on the slip rings are also tightly combined to form an integral sliding groove, ensuring that the slider can be stuck in the sliding groove and slide smoothly.

[0041] The slip ring structure described in this embodiment adopts a half-type concave-convex joint, similar to a mortise and tenon joint. The concave-convex structure limits each other and fits tightly, which can ensure the accuracy of the connection and positioning of the slide groove on the slider and facilitates the smooth sliding of the slider in the slide groove.

[0042] Six sliding balls 18 are installed on the slider 17. The sliding balls 18 can be precisely engaged in the grooves of the first slip ring 15 and the second slip ring 16. The force of the sliding balls 18 on the grooves is adjusted by the threads to both keep them engaged in the grooves to prevent the slider 17 from sliding out, and to allow the sliding balls 18 to roll smoothly in the grooves. On each side of the groove, two sliding balls 18 are positioned opposite each other to restrict the radial freedom of the slider 17 in the first slip ring 15 and the second slip ring 16. Two other sliding balls 18 are above the slider 17 and are engaged in the circumferential grooves of the first slip ring 15 and the second slip ring 16 to limit the axial movement of the slip ring 17. In this way, the slider 17 is supported by the six sliding balls 18. The sliding balls 18 slide in pairs in one of the grooves of the slip ring 17. The six sliding balls 18 supporting the slider 17 can only slide in the circumferential direction of the first slip ring 15 and the second slip ring 16.

[0043] The slider 17 can be positioned in both radial and axial directions on the first slip ring 15 and the second slip ring 16. The tension of the sliding ball 18 on the slider 17 over the slide groove is adjustable, and it can rotate continuously 360 degrees on the first slip ring 15 and the second slip ring 16.

[0044] To ensure a constant tension between the sliding ball 18 and the first slip ring 15 and the second slip ring 16, the sliding ball 18 must not come loose during movement. A positioning screw 19 is provided on the slider 17 corresponding to the sliding ball 18. By tightening the positioning screw 19, the sliding ball 18 can be fixed to the slider 17. This achieves the desired fixing force between the sliding ball 18 and the groove, ensuring smooth sliding.

[0045] by Figure 2 As shown in the example, when the joint of the robotic arm twists, there is a relative rotation between the D-axis 10 and the E-axis 11 of the robotic arm. The cable connector 22 on the E-axis 11 of the robotic arm will cause the fixed point of the cable 12 on the D-axis 10 of the robotic arm to twist to one side. If the fixed point of the cable 12 on the D-axis 10 of the robotic arm is fixed, the cable 12 will be resisted here. The D-axis 10 and the E-axis 11 of the robotic arm will either not be able to rotate, or the cable bracket 13 will be damaged due to the inability to withstand the torque. At this time, since the fixed point of the cable 12 is fixed on the slider 17, when the twisting occurs, the slider 17 will follow the cable 12 with the force of the cable 12. This avoids the cable 12 being pulled and protects the cable 12 and the cable bracket 13.

[0046] The first slip ring 15 and the second slip ring 16 mentioned above are used on the robotic arm shaft. They can be configured according to the joint torsion requirements of the robotic arm. It is not necessary to use only one. They can be flexibly used according to the rotation requirements of the robotic arm shaft.

[0047] This embodiment explains the problem of preventing cable twisting by explaining a set of slip ring assemblies, and only addresses the rotation between the D and E axes of the robotic arm assembly. However, if other robotic arm axes cannot successfully self-lock, or if the robotic arm requires more room to maneuver, the other cable support assembly 5 can be replaced with the slip ring assembly 4 to achieve greater freedom of cable movement. The degree of expansion can be determined according to the site requirements.

[0048] Since the external cables attached to the robotic arm are the only connection for communication and power supply between the end effector and the inspection robot, the cables must be fixed to the arms on both sides of the joints. The numerous joints in the robotic arm present challenges to the cable's movement. On one hand, it's necessary to increase the redundancy of the cables at each fixing point to prevent tangling between the end effector's cables and the robotic arm due to arm movement. On the other hand, the robotic arm joints inevitably rotate. When the cables are subjected to the torque of joint rotation, they should also move accordingly to avoid or reduce pulling, thus protecting the equipment and cables. Based on these objectives, a slip ring-type slider structure is installed on the robotic arm to fix the cables to the sliders. When the cables are pulled by the joints, the sliders slide along the slip rings with the cables, which can eliminate or reduce the pulling effect of joint movement on the cable fixation to a certain extent, thereby protecting the cables and the normal movement of the robotic arm.

[0049] Example 2

[0050] This embodiment provides a control method for a cable follower device on a robotic arm.

[0051] A control method for a cable follower device on a robotic arm, applied to the cable follower device on a robotic arm as described in Embodiment 1, includes: relative rotation between the D-axis and E-axis of the robotic arm, and the cable connector on the E-axis of the robotic arm causing the slider of the cable on the D-axis of the robotic arm to twist to one side, so that the slider slides around the slip ring along the slide groove.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A mechanical arm wire following device, characterized by, include: At least one cable fixing structure and a slip ring assembly are provided on the robotic arm. The slip ring assembly includes a slip ring, a slider and a sliding glass ball. The slip ring includes a first slip ring and a second slip ring. The slip ring is mounted on the robotic arm and has a sliding groove. The slider slides by sliding the glass ball inserted into the sliding groove. The slider has a first cable bracket, and the cable passes through the first cable bracket and the cable fixing structure. The slip ring is provided with grooves on its upper surface and two sides; The slider can be positioned radially and axially on the first and second slip rings, and the tension of the sliding glass ball on the slider against the slide groove is adjustable, and it can rotate continuously 360 degrees on the first and second slip rings.

2. The cable follower device on the robotic arm according to claim 1, characterized in that, The slider is provided with a positioning screw at the corresponding position of the sliding glass bead, which is used to fix the sliding glass bead on the slider.

3. The cable follower device on the robotic arm according to claim 1, characterized in that, The cable fixing structure includes a steel strip, a cable bracket, and a second cable bracket. The steel strip is sleeved on the robotic arm, the cable bracket is used to fix the steel strip, and the second cable bracket is installed on the cable bracket.

4. The cable follower device on the robotic arm according to claim 3, characterized in that, The second cable bracket is fixed to the cable bracket support by countersunk screws, and the cable passes through the second cable bracket.

5. The cable follower device on the robotic arm according to claim 3, characterized in that, The robotic arm includes robotic arm A-axis, robotic arm B-axis, robotic arm C-axis, robotic arm D-axis, and robotic arm E-axis, which are connected to the end device by a robotic arm base.

6. The cable follower device on the robotic arm according to claim 5, characterized in that, The cable support bracket moves synchronously with the E-axis of the robotic arm end.

7. The cable follower device on the robotic arm according to claim 1, characterized in that, The first slip ring and the second slip ring are fixed together by countersunk screws to form a slip ring.

8. The cable follower device on the robotic arm according to claim 1, characterized in that, One end of the cable is fixed to the end device, and the other end is fixed to the base of the robotic arm.

9. A control method for a cable follower device on a robotic arm, characterized in that, The cable follower device applied to the robotic arm according to any one of claims 5-6 includes: relative rotation between the D-axis and E-axis of the robotic arm, and the cable connector on the E-axis of the robotic arm causing the slider of the cable on the D-axis of the robotic arm to twist to one side, so that the slider slides around the slip ring along the slide groove.

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