Self-walking variable-structure exoskeleton robot

Abstract

The application discloses a self-walking variable-configuration outer-limb robot, and belongs to the field of human-machine collaborative robot equipment. The robot comprises a wearable backpack and a mechanical limb. The mechanical limb is arranged on the wearable backpack. The mechanical limb comprises: a rotary joint, two rotary parts of which are connected with an arm rod respectively; the arm rod is connected with a three-degree-of-freedom wrist; the three-degree-of-freedom wrist is connected with an electric permanent magnet quick-change connecting mechanism, so that the mechanical limb has the degrees of freedom of rotation, pitching or synchronous rotation and pitching; the electric permanent magnet quick-change connecting mechanism is used for automatically switching the outer-limb robot on the wearable backpack into different configurations; and the arm rod, the three-degree-of-freedom wrist and the electric permanent magnet quick-change connecting mechanism are symmetrically arranged respectively. The application can realize the self-walking action on the wearable backpack, and can realize the self-variable-configuration function of the outer limb by cooperating with the electric permanent magnet interface, so that the outer-limb robot can adapt to more complex and diverse working conditions.

Description

Technical Field

[0001] This invention relates to a robot, specifically a self-propelled variable-structure exolimb robot, belonging to the field of human-robot collaborative robot equipment. Background Technology

[0002] Exolimb robots are a new type of wearable assistive robot. Independent of the wearer's limbs and not constrained by the wearer's limb movements, exolimb robots do not replace human limbs. Instead, they serve as redundant limbs to extend the wearer's operational capabilities and assist in completing tasks. With the assistance of exolimbs, wearers can perform tasks that are prone to fatigue, relatively dangerous, or otherwise difficult for humans to complete independently. They hold immense application potential in fields such as industrial production, rehabilitation medicine, and national defense.

[0003] As an emerging type of wearable assistive robot, exolimb robots still have some shortcomings. The optimal placement and allocation of mechanical limbs remains unresolved, and the required positions of these limbs vary depending on the specific task. Improving the adaptability of exolimb robots to different tasks is a crucial issue. While existing solutions increase the number of mechanical limbs to enhance adaptability, this directly increases the overall weight of the device, placing an unnecessary burden on the wearer. Furthermore, although some solutions propose variable-configuration exolimbs using modular designs to improve interchangeability and reduce the difficulty of configuration changes, the mechanical and electrical interfaces of such solutions remain complex, hindering rapid configuration changes.

[0004] In summary, existing exolimb robots have weak multi-task adaptability, and their mechanical and electrical interfaces remain relatively complex, making it difficult to achieve rapid reconfiguration. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by proposing a self-propelled, variable-configuration exoskeleton robot. The robot employs an electro-permanent magnet connection interface for easy connection and disconnection, enabling convenient and quick mechanical and electrical connections of the mechanical limbs. Simultaneously, it utilizes a symmetrical design, allowing the mechanical limbs to autonomously move between pre-reserved interfaces on a wearable backpack via controlled propulsion, thus achieving automatic configuration changes and significantly enhancing the exoskeleton robot's multi-tasking adaptability.

[0006] A self-propelled, variable-configuration exolimb robot comprises a wearable backpack and mechanical limbs; the mechanical limbs are mounted on the wearable backpack.

[0007] The mechanical limb includes:

[0008] A rotary joint, in which two opposite rotary parts are each connected to a boom;

[0009] The arm connects to the three-degree-of-freedom wrist;

[0010] A three-degree-of-freedom wrist, connected to an electro-permanent magnet quick-change connection mechanism, gives the mechanical limb the freedom of rotation, pitch, or simultaneous rotation and pitch.

[0011] An electro-permanent magnet quick-change connection mechanism is used for the exolimb robot to autonomously switch between different configurations on a wearable backpack;

[0012] The arm, three-degree-of-freedom wrist, and electro-permanent magnet quick-change connection mechanism are each arranged symmetrically. The mechanical limb has seven rotational degrees of freedom.

[0013] Furthermore, the rotary joint includes an upper housing, a lower housing, and a drive unit; the drive unit is mounted on the lower housing and is used to drive the upper housing to rotate; the upper housing and the lower housing are respectively connected to the arm.

[0014] Furthermore, the three-degree-of-freedom wrist includes: a rotary part for driving the differential drive part to rotate; the differential drive part for driving the differential transmission part to rotate, pitch, or rotate and pitch synchronously; the differential transmission part has its output end connected to an electro-permanent magnet quick-change connection mechanism to realize that the electro-permanent magnet quick-change connection mechanism moves synchronously under the movement of the differential transmission part.

[0015] Furthermore, the electro-permanent magnet quick-change connection mechanism includes a connecting housing, a circuit board, an electro-permanent magnet, and a chassis; the connecting housing is installed at the end of the end bevel gear shaft of the three-degree-of-freedom wrist, the electro-permanent magnet is installed on the chassis, and the circuit board is located between the connecting housing and the chassis to supply power to the electro-permanent magnet and to magnetize and demagnetize the electro-permanent magnet according to the sending of positive or negative pulse current, and the connecting housing and the chassis are connected.

[0016] The advantages of this invention compared to the prior art are:

[0017] The symmetrical design of the mechanical limbs enables the robot to perform actions similar to autonomous walking while wearing a backpack. Combined with the electro-permanent magnet interface, it can realize the autonomous configuration function of the external limbs, allowing the external limb robot to adapt to more complex and diverse working conditions.

[0018] Second, the differential three-degree-of-freedom robot wrist used in this application has the characteristics of flexible movement, strong load output capacity and compact space, which makes the mechanical limb have strong flexibility and operation capabilities.

[0019] Third, the rotary joint used in this application adopts a dual-motor backlash-free drive, which improves the control accuracy and load capacity of the mechanical limb.

[0020] Fourth, this application adopts an electro-permanent magnet quick-change method, which takes into account the needs of both mechanical and electrical interfaces, reduces the difficulty of connecting and disconnecting the mechanical limb from the wearable backpack, greatly improves the quick-change efficiency, and provides the possibility for the automated switching of mechanical limbs.

[0021] The present application will be further described below with reference to the accompanying drawings and embodiments: Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the mechanical limb in this application;

[0023] Figure 2 This is a diagram showing the state of the mechanical limb undergoing self-walking transformation on a wearable backpack in the embodiment;

[0024] Figure 3 The diagram shows a 3D view of the rotary joint and its corresponding exploded view.

[0025] Figure 4 These are the front view and main sectional view of the rotary joint;

[0026] Figure 5 This is a diagram showing the components and connections of the boom;

[0027] Figure 6 A stereoscopic view of a three-degree-of-freedom wrist;

[0028] Figure 7 This is a schematic diagram of the rotational portion of a three-degree-of-freedom wrist.

[0029] Figure 8 This is a schematic diagram showing the connection between the differential drive section and the differential transmission section;

[0030] Figure 9 This is a schematic diagram of the differential drive mechanism of a three-degree-of-freedom wrist.

[0031] Figure 10 This is a schematic diagram of power transmission via a synchronous belt.

[0032] Figure 11 This is a schematic diagram of the differential transmission part of a three-degree-of-freedom wrist.

[0033] Figure 12 This is a schematic diagram of an electro-permanent magnet quick-change connection mechanism. Detailed Implementation

[0034] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. Unless otherwise stated, the technical or scientific terms used in this application have the ordinary meanings understood by those skilled in the art.

[0035] Reference Figure 1 and Figure 2A self-propelled, variable-configuration exolimb robot includes a wearable backpack E and a mechanical limb; the mechanical limb is mounted on the wearable backpack E.

[0036] The mechanical limb includes:

[0037] Rotary joint A, whose two opposite rotating parts are each connected to a boom B;

[0038] Arm B connects to a three-degree-of-freedom wrist C;

[0039] The three-degree-of-freedom wrist C is connected to the electro-permanent magnet quick-change connection mechanism D, giving the mechanical limb the degrees of freedom of rotation, pitch, or simultaneous rotation and pitch.

[0040] The electro-permanent magnet quick-change connection mechanism D is used for the exolimb robot to autonomously switch between different configurations on the wearable backpack E;

[0041] The arm B, the three-degree-of-freedom wrist C, and the electro-permanent magnet quick-change connection mechanism D are each symmetrically arranged. That is, each robotic limb includes one rotary joint A, two arm Bs, two three-degree-of-freedom wrists C, and two electro-permanent magnet quick-change connection devices D. The two three-degree-of-freedom wrists C have a total of 6 degrees of freedom, the rotary joint A has 1 rotational degree of freedom, and a single robotic limb has seven rotational degrees of freedom. Its overall joint configuration adopts a symmetrical arrangement. Due to the symmetrical design of the robotic limb, through the process of "end-effector movement to a predetermined interface point – end-effector magnetization – end-effector connection – base demagnetization – base disconnection," the robotic limb can "self-walk" on a wearable backpack, thereby moving to a designated interface position and forming a specific configuration. Figure 2 (a) is the top-of-the-head configuration. Figure 2 (b) is the shoulder configuration. Figure 2 (c) is the waist configuration.

[0042] Furthermore, referring to Figures 3-4 The rotary joint A includes an upper housing A1, a lower housing A8, and a drive unit A7. The drive unit A7 is mounted on the lower housing A8 and is used to drive the upper housing A1 to rotate. The upper housing A1 and the lower housing A8 are respectively connected to the arm B. The upper housing A1 and the lower housing A8 of the rotary joint A are connected to the arm B by threads.

[0043] For example: each rotary joint A includes two drive units A7, each drive unit A7 having two symmetrically distributed, each drive unit A7 including a servo and an output gear; the output gear is mounted on the output end of the servo, the servo is mounted on the lower housing A8, the upper part of the lower housing A8 is provided with an internal gear ring A5 that can rotate relative to the lower housing A8, the output gear meshes with the internal gear ring A5, and the internal gear ring A5 is connected to the upper housing A1.

[0044] For example: refer to Figure 4 , Figure 4 (a) is the front view of rotary joint A. Figure 4 (b) is Figure 4 (a) A cross-sectional view along line FF; as shown in the figure: two drive units A7 are mounted on drive unit mounting plate A6, and then drive unit mounting plate A6 and lower housing A8 are fixed together by threaded connection. A rolling bearing A4 is mounted on the upper part of drive unit mounting plate A6, and bearing end cover A2 is installed on the upper end of drive unit mounting plate A6 by threaded connection, together with drive unit mounting plate A6 fixing the inner ring of rolling bearing A4. The output gears of the two drive units A7 mesh with internal gear rings A5, and internal gear rings A5 are fixed to upper housing connector A3 by threaded connection, simultaneously constraining the outer ring of rolling bearing A4. Upper housing connector A3 is fixed to upper housing A1 by threaded connection, thus allowing the output of drive unit A7 to be transmitted to upper housing A1.

[0045] For example, the upper housing A1, bearing end cover A2, upper housing connector A3, drive unit mounting plate A6 and lower housing A8 are all hollow, leaving sufficient space for later electrical wiring.

[0046] For boom B, refer to Figure 5 It includes a rotary joint connector B1 and a main rod B2. One end of the rotary joint connector B1 and the main rod B2 are connected and fixed by bolts and nuts. The rotary joint connector B1 is connected to the upper outer shell A1 and the lower outer shell A8 of the rotary joint A respectively. The other end of the main rod B2 is connected to the rotary part C1 of the three-degree-of-freedom wrist C.

[0047] Furthermore, referring to Figure 6 The three-degree-of-freedom wrist C includes:

[0048] Rotating part C1; used to drive the differential drive part C2 to rotate;

[0049] The differential drive section C2 is used to drive the differential transmission section C3 to rotate, pitch, or rotate and pitch synchronously.

[0050] The differential transmission part C3 has its output end connected to the electro-permanent magnet quick-change connection mechanism D, so as to realize that the electro-permanent magnet quick-change connection mechanism D moves synchronously when the differential transmission part C3 moves.

[0051] The rotating part C1 is provided with a differential drive part C2 and a differential transmission part C3 in sequence, which ultimately drives the differential transmission part C3 to rotate around the axis.

[0052] For example, refer to Figure 7 ,in Figure 7(a) is the front view of the rotating part. Figure 7 (b) is Figure 7 (a) is a cross-sectional view along line HH. The rotating part C1 includes a rotating housing C1-1, a differential housing C1-3, a large bevel gear C1-5, a small bevel gear C1-6, and a rotating drive servo motor C1-7.

[0053] A rotary drive servo C1-7 is mounted on a rotary housing C1-1. A small bevel gear C1-6 is mounted on the output end of the rotary drive servo C1-7. The small bevel gear C1-6 meshes with a large bevel gear C1-5. The large bevel gear C1-5 is connected to the lower half of the differential housing C1-3. The differential housing C1-3 is rotatably mounted on the rotary housing C1-1. A differential drive section C2 is located on the top of the differential housing C1-3.

[0054] Specifically, two rolling bearings C1-4 are installed between the rotary housing C1-1 and the differential housing C1-3, and the shaft system of the rotary part is installed and fixed through the rotary bearing retaining ring C1-2. The rotary housing C1-1, the large bevel gear C1-5 and the differential housing C1-3 have certain spaces and through holes for wiring of electronic devices such as motors and sensors.

[0055] For example, refer to Figure 8 and Figure 9 ,in Figure 9 (a) is a three-dimensional view of the differential drive section. Figure 9 (b) is a partial cross-sectional view of the differential drive section. Two differential drive sections C2 are installed in the upper half of the differential housing C1-3, with each section C2 installed diagonally opposite each other within the housing. Each differential drive section C2 includes a pulley C2-1, a differential drive servo C2-2, and a timing belt C2-5. The pulley C2-1 is mounted on the servo disc of the differential drive servo C2-2, and transmits power to the differential transmission section C3 via the timing belt C2-5.

[0056] Reference Figure 9 (a) The differential drive part C2 further includes a tensioning idler bracket C2-3, an idler C2-6, an idler bearing retainer C2-7, and a miniature bearing C2-8; each end of the idler C2-6 is equipped with a miniature bearing C2-8, and is fixed to the shaft of the tensioning idler bracket C2-3 by the idler bearing retainer C2-7. The tensioning idler bracket C2-3 is movably connected to the drive servo C2-2 and is used for the adjustment and tensioning of the synchronous belt C2-5.

[0057] Specifically, refer to Figure 8 and Figure 9(b) The pulley C2-1 is mounted on the rudder disc of the drive servo C2-2. Each end of the idler pulley C2-6 is fitted with a miniature bearing C2-8, which is fixed to the shaft of the tension idler pulley bracket C2-3 via idler pulley bearing retaining rings C2-7, forming a synchronous belt tensioning device. The connection end between the tension idler pulley bracket C2-3 and the drive servo C2-2 is in the form of a slot, leaving adjustable space along the slot direction for adjusting and tensioning the synchronous belt.

[0058] For example, refer to Figure 10 and Figure 11 The differential transmission part includes a central shaft C3-2, an end bevel gear shaft C3-3, a differential bracket C3-6, and two sets of combined wheels C3-1. The central shaft C3-2 is rotatably mounted on the differential housing C1-3. Each set of combined wheels C3-1 includes a synchronous pulley and a bevel gear connected coaxially. The two sets of combined wheels C3-1 are rotatably mounted at both ends of the central shaft C3-2. The pulley C2-1 transmits power to the synchronous pulley of the combined wheel C3-1 through the synchronous belt C2-5. The bevel gear of the combined wheel C3-1 meshes with the bevel gear of the end bevel gear shaft C3-3. The differential bracket C3-6 is mounted at both ends of the central shaft C2, and the end bevel gear shaft C3-3 is rotatably mounted on the differential bracket C3-6.

[0059] Specifically, refer to Figure 11 ,in Figure 11 (a) is a front view of the differential transmission section. Figure 11 (b) is Figure 11 (a) is a cross-sectional view along line NN; the differential transmission part C3 uses bevel gear differential transmission. The central shaft C3-2 is a stepped shaft with a stepped hole perpendicular to the axis at its center. The end bevel gear shaft C3-3 and the rolling bearing C3-9 are installed in the stepped hole. Each combination wheel C3-1 is equipped with two rolling bearings C3-4, which are installed on both sides of the central shaft C3-2, forming a differential transmission system together with the end bevel gear shaft C3-3. The central shaft sleeve C3-8 is used to fix the bearings and the components on the shaft. The differential bracket C3-6 is fixed to both ends of the central shaft C3-2. It is a fork-shaped piece with a stepped hole in the middle, and a bearing C3-7 is installed thereto, which serves to fix the end bevel gear shaft C3-3.

[0060] Reference Figure 10 , Figure 10 (a) is a front view of a synchronous belt drive. Figure 10 (b) is Figure 10 (a) is a cross-sectional view along line KK, from which... Figure 10(b) It can be seen that the differential drive section C2 transmits power to the differential transmission section C3 via a synchronous belt drive. The power is transmitted through the synchronous belt C2-5, through the small pulley C2-1 to the combined pulley C3-1, and tensioned from the outside of the synchronous belt C2-5 by the idler pulley C2-6. The combined pulley C3-1 consists of a synchronous pulley and a bevel gear, and can be installed as a whole or as two separate parts. Two combined pulleys C3-1 are mounted on the central shaft C3-2, and are mounted on the two side supports of the differential housing C1-3 via rolling bearings C3-5, and are fixed on both sides by bearing bushes C2-4.

[0061] For example, refer to Figure 12 The electro-permanent magnet quick-change connection mechanism D includes a connecting housing D1, a circuit board D2, an electro-permanent magnet D3, and a chassis D4. The connecting housing D1 is installed at the end of the bevel gear shaft C3-3 of the three-degree-of-freedom wrist C. The circuit board D2 has mounting and positioning holes that align with the holes in the connecting housing D1 and the chassis D4. The electro-permanent magnet D3 is installed in the mounting groove of the chassis D4. When the connecting housing D1 and the chassis D4 are connected and fixed by bolts and nuts, the circuit board D2 and the electro-permanent magnet D3 are pressed and fixed together. The connecting housing D1 and the chassis D4 are connected, and the electro-permanent magnet... D3 is mounted on and extends from chassis D4. Circuit board D2 is positioned between the connecting shell D1 and chassis D4. The electro-permanent magnet quick-change device can power the electro-permanent magnet D3 via circuit board D2 and magnetize and demagnetize it by sending forward or reverse pulse current. Simultaneously, electromagnetic interfaces matching the quick-change device are respectively located at the back of the neck, shoulders, and waist of the wearer's backpack E. These interfaces can be mechanically connected to the quick-change device via magnetic attraction, and current and control signals are transmitted through the electro-permanent magnet and the device's internal circuitry. This enables rapid mechanical and electrical switching between the seven-DOF robotic limb and the wearable backpack. Furthermore, due to the symmetrical design of the robotic limb, it can "self-walk" on the wearable backpack by following the sequence of "end-end movement to a predetermined interface point – end-end magnetization – end-end connection – base demagnetization – base disconnection," thus moving to the designated interface position and forming a specific configuration.

[0062] For example, the self-propelled variable-configuration exolimb robot based on the above implementation scheme can provide body support and safety protection for the wearer when the operator needs to operate in a kneeling or squatting posture or other fatigue-prone working posture. It can also provide auxiliary lighting, gripping, and operation functions for the wearer in the form of additional mechanical limbs by installing end-effectors.

[0063] This application has disclosed the preferred embodiments as above, but it is not intended to limit this application. Any person skilled in the art who can make some changes or modifications to the above-disclosed structure and technical content to create equivalent embodiments without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A self-propelled, variable-configuration exolimb robot, characterized in that: Includes a wearable backpack (E) and mechanical limbs; The mechanical limbs are mounted on a wearable backpack (E); The mechanical limb includes: A rotary joint (A) has two opposite rotary parts connected to a boom (B); The rotary joint (A) includes an upper housing (A1), a lower housing (A8), and a drive unit (A7); the drive unit (A7) is mounted on the lower housing (A8) and is used to drive the upper housing (A1) to rotate. The upper housing (A1) and the lower housing (A8) are respectively connected to the arm (B). The drive unit (A7) has two symmetrically distributed units, each of which includes a servo motor and an output gear. The output gear is installed at the output end of the servo motor, which is installed on the lower housing (A8). An internal gear ring (A5) that can rotate relative to the lower housing (A8) is provided on the upper part of the lower housing (A8). The output gear meshes with the internal gear ring (A5), and the internal gear ring (A5) is connected to the upper housing (A1). Arm (B) is connected to a three-degree-of-freedom wrist (C); A three-degree-of-freedom wrist (C) is connected to an electro-permanent magnet quick-change connection mechanism (D), giving the robotic limb rotational, pitching, or simultaneous rotational and pitching degrees of freedom. The electro-permanent magnet quick-change connection mechanism (D) is used for the exolimb robot to autonomously switch between different configurations on a wearable backpack (E). The arm (B), the three-degree-of-freedom wrist (C), and the electro-permanent magnet quick-change connection mechanism (D) are symmetrically arranged. The electro-permanent magnet quick-change connection mechanism (D) includes a connecting housing (D1), a circuit board (D2), an electro-permanent magnet (D3), and a chassis (D4). The connecting housing (D1) is mounted on the end bevel gear shaft (C3) of the three-degree-of-freedom wrist (C). -3) At the end, the electro-permanent magnet (D3) is installed on the chassis (D4), and the circuit board (D2) is set between the connecting shell (D1) and the chassis (D4) to supply power to the electro-permanent magnet (D3) and to magnetize and demagnetize the electro-permanent magnet (D3) according to the sending of positive or negative pulse current. The connecting shell (D1) and the chassis (D4) are connected. The wearable backpack (E) is provided with electromagnetic interfaces that are compatible with the electro-permanent magnet quick-change connection mechanism (D) for the back of the neck, shoulders and waist of the wearer, respectively, so that the mechanical limb can switch between the head, shoulder and waist configurations in a self-walking manner on the wearable backpack (E).

2. The self-propelled variable-configuration exolimb robot according to claim 1, characterized in that: The three-degree-of-freedom wrist (C) includes: The slewing section (C1) is used to drive the differential drive section (C2) to rotate; The differential drive section (C2) is used to drive the differential transmission section (C3) to rotate, pitch, or rotate and pitch synchronously. The differential transmission part (C3) is connected to the electro-permanent magnet quick-change connection mechanism (D) at its output end, so as to realize that the electro-permanent magnet quick-change connection mechanism (D) moves synchronously under the movement of the differential transmission part (C3).

3. The self-propelled variable-configuration exolimb robot according to claim 2, characterized in that: The rotating part (C1) includes a rotating housing (C1-1), a differential housing (C1-3), a large bevel gear (C1-5), a small bevel gear (C1-6), and a rotating drive servo motor (C1-7). A rotary drive servo (C1-7) is mounted on a rotary housing (C1-1). A small bevel gear (C1-6) is mounted on the output end of the rotary drive servo (C1-7). The small bevel gear (C1-6) meshes with a large bevel gear (C1-5). The large bevel gear (C1-5) is connected to the lower half of the differential housing (C1-3). The differential housing (C1-3) is rotatably mounted on the rotary housing (C1-1). A differential drive section (C2) is located on the top of the differential housing (C1-3).

4. The self-propelled variable-configuration exolimb robot according to claim 3, characterized in that: The upper cavity of the differential housing (C1-3) contains two differential drive parts (C2). Each differential drive part (C2) is installed opposite to each other in the cavity. Each differential drive part (C2) includes a pulley (C2-1), a differential drive servo (C2-2), and a timing belt (C2-5). The pulley (C2-1) is mounted on the servo disk of the differential drive servo (C2-2), and the pulley (C2-1) transmits power to the differential transmission part (C3) through the timing belt (C2-5).

5. The self-propelled variable-configuration exolimb robot according to claim 4, characterized in that: The differential transmission part includes a central shaft (C3-2), an end bevel gear shaft (C3-3), a differential bracket (C3-6), and two sets of combined pulleys (C3-1). The central shaft (C3-2) is rotatably mounted on the differential housing (C1-3). Each set of combined pulleys (C3-1) includes a synchronous pulley and a bevel gear connected coaxially. The two sets of combined pulleys (C3-1) are rotatably mounted at both ends of the central shaft (C3-2). The pulley (C2-1) transmits power to the synchronous pulley of the combined pulley (C3-1) through a synchronous belt (C2-5). The bevel gear of the combined pulley (C3-1) meshes with the bevel gear of the end bevel gear shaft (C3-3). The differential bracket (C3-6) is mounted at both ends of the central shaft (C3-2), and the end bevel gear shaft (C3-3) is rotatably mounted on the differential bracket (C3-6).

6. The self-propelled variable-configuration exolimb robot according to claim 4, characterized in that: The differential drive section (C2) also includes a tension idler bracket (C2-3), an idler (C2-6), an idler bearing retainer (C2-7), and a miniature bearing (C2-8). Each end of the idler wheel (C2-6) is equipped with a miniature bearing (C2-8), which is fixed to the shaft of the tension idler wheel bracket (C2-3) by the idler wheel bearing retainer ring (C2-7). The tension idler wheel bracket (C2-3) is movably connected to the drive servo (C2-2) and is used for adjusting and tensioning the synchronous belt (C2-5).

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