Under-actuated traction device based on planetary gear differential mechanism and hand exoskeleton

Abstract

The present application belongs to the technical field of under-actuated structure design, and discloses an under-actuated traction device based on a planetary gear differential mechanism and a hand exoskeleton, wherein the traction device comprises a two-input four-output under-actuated traction module, a motor wire wheel direct drive traction module and a wire wheel output tensioning module; the two-input four-output under-actuated traction module is connected with the motor wire wheel direct drive traction module, and both are connected with the wire wheel output tensioning module; the motor wire wheel direct drive traction module is used for providing forward and reverse traction force for an actuator; the two-input four-output under-actuated traction module is a driving mechanism for converting two input forces into four output driving forces through the proportional action of the planetary gear differential mechanism, so that two power inputs become four power outputs. The two-input four-output under-actuated traction module is a driving device for converting the power input from two motors into four output driving forces through the proportional action of the planetary gear differential mechanism, so that two power sources become four power sources.

Description

Technical Field

[0001] This invention belongs to the technical field of underactuated structure design, and more specifically, relates to an underactuated traction device and a hand exoskeleton based on a planetary gear differential mechanism. Background Technology

[0002] With the continuous development of dimensionality reduction theory, the theory of using low-dimensional motion to affine high-dimensional motion continues to advance. Underactuated structures are welcomed by researchers due to their low power source input and strong output capability, especially in hand-related design directions.

[0003] In recent years, many researchers have made continuous efforts and achieved many results in the design of underactuated structures, but there has been no significant improvement in the use of underactuated structures for rope traction. For example, the underactuated exoskeleton rehabilitation manipulator based on gear transmission described in invention patent CN11529308A adopts a planetary gear transmission method, but the linkage mechanism uses a linkage transmission, which is relatively bulky and not suitable for long-distance power transmission. Another example is the hand exoskeleton device with underactuated traction function described in invention patent CN114259383A, whose hand traction device is rope driven. However, the overall rope length variation is limited by the length of the structure, resulting in poor wearability for different hand sizes and unstable stroke. Summary of the Invention

[0004] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides an underdriven traction device and a hand exoskeleton based on a planetary gear differential mechanism. Its motor-coil direct drive module can provide forward and reverse traction forces for actuators that require reciprocating motion of the coil. The two-input four-output underdriven traction module is a drive device that converts the power input from two motors into four outputs through the proportional action of the planetary gear differential mechanism, thus changing the original two power source inputs into four power source outputs.

[0005] To achieve the above objectives, according to one aspect of the present invention, an underdriven traction device based on a planetary gear differential mechanism is provided. The traction device includes a two-input four-output underdriven traction module, a motor-coil direct-drive traction module, and a coil output tensioning module. The two-input four-output underdriven traction module is connected to the motor-coil direct-drive traction module, and both are respectively connected to the coil output tensioning module.

[0006] The motor pulley direct drive traction module is used to provide forward and reverse traction force to the actuator; the two-input four-output underdriven traction module is a drive mechanism that converts two input forces into four outputs through the proportional action of the planetary gear differential mechanism, so that two power inputs become four power outputs.

[0007] Furthermore, the two-input four-output underdriven traction module includes two direct drive modules and two planetary gear differential mechanisms. The two direct drive modules are connected and arranged in the same direction. The two planetary gear differential mechanisms are respectively arranged on opposite sides of the direct drive modules and are meshed with the direct drive modules.

[0008] Furthermore, each of the direct drive modules and each of the two planetary gear differential mechanisms provides a power source output.

[0009] Furthermore, the two direct-drive modules are symmetrically arranged and have the same structure; each direct-drive module includes a harmonic brushless motor, a motor mounting base, a first bearing housing, a second bearing housing, a first spool, a drive gear, and a motor output shaft. The first bearing housing and the second bearing housing are spaced apart on a carbon fiber base plate. The harmonic brushless motor is mounted on the motor mounting base. The motor mounting base is fixed to the first bearing housing. The output port of the harmonic brushless motor is connected to the motor output shaft. A first keyway is provided on the motor output shaft, and a second keyway is provided inside the drive gear. The first keyway and the second keyway are fixed to a key fixed on the first spool. The two ends of the first spool are respectively mounted on the first bearing housing and the second bearing housing via bearings.

[0010] Furthermore, the two planetary gear differential mechanisms have the same structure and are meshed with the direct drive module.

[0011] Furthermore, the planetary gear differential mechanism includes a second driven bearing housing, a first driven gear, a first driven gear ring, a second spool, planetary gears, a second driven gear, a driven sun gear shaft, and a first driven bearing housing; the first driven bearing and the second driven bearing are spaced apart on the carbon fiber base plate; the first driven gear and the second driven gear respectively mesh with the drive gears of the two direct drive modules; the first driven gear is fixedly connected to the first driven gear ring; both ends of the driven sun gear shaft are respectively mounted on the first driven bearing housing and the second driven bearing via bearings, and pass through the first driven gear; the second spool is sleeved on the driven sun gear shaft via a bearing; the second driven gear is fixed on the driven sun gear shaft by a key.

[0012] Furthermore, a central gear is fixed on the driven sun gear shaft. The central gear is located inside the first driven gear ring and meshes with both the first driven gear ring and the planetary gear. The middle part of the planetary gear is fixedly connected to the second spool.

[0013] Furthermore, the two motor-driven sheave direct drive traction modules are symmetrically arranged on the carbon fiber base plate and have the same structure; the motor-driven sheave direct drive traction module includes a direct drive motor, a direct drive flange and a direct drive sheave, and the direct drive motor transmits power to the direct drive sheave through the direct drive flange in the form of a keyway connection.

[0014] Furthermore, the motion of the two direct-drive spools, the two second spools, and the two first spools is respectively connected to the corresponding actuators through the spool output tensioning module, so as to transmit the motion of the spools to the actuators.

[0015] The present invention also provides a hand exoskeleton, which includes a connected prosthetic hand and an underactuated traction device based on a planetary gear differential mechanism as described above.

[0016] In summary, compared with the prior art, the underactuated traction device and hand exoskeleton based on the planetary gear differential mechanism provided by the present invention have the following beneficial effects:

[0017] 1. The underactuated traction device provided by the present invention can provide a motion traction solution for coordinated flexion / extension of four fingers, flexion / extension of the thumb, and lateral swing of the thumb, in order to meet the needs of hand exoskeleton use.

[0018] 2. The underactuated traction device of the present invention provides a method for quantifying the motion ratio output of a two-input four-output proportional adjustment mechanism, namely, proportional adjustment by changing the planetary gear transmission ratio.

[0019] 3. The cable pulley output tensioning module of the present invention provides a function for adjusting the stroke when there is a difference in the stroke of the actuator in the rope-driven traction mechanism. It is a rope pretensioning device based on a one-way bearing rubber-coated pulley. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of an underdriven traction device based on a planetary gear differential mechanism provided by the present invention;

[0021] Figure 2 yes Figure 1 A schematic diagram of a pulley drive in an underdriven traction device based on a planetary gear differential mechanism;

[0022] Figure 3 yes Figure 1 An exploded view of the direct drive module of the two-input four-output underdrive traction module of the underdrive traction device based on planetary gear differential mechanism in the paper.

[0023] Figure 4 yes Figure 1An exploded view of the planetary gear differential mechanism in the two-input four-output underactuated traction module of the planetary gear differential mechanism-based underactuated traction device.

[0024] Figure 5 yes Figure 1 A schematic diagram of the direct drive sheave of the motor sheave direct drive traction module in the underdriven traction device based on planetary gear differential mechanism;

[0025] Figure 6 In the middle (a) and (b) respectively Figure 1 A schematic diagram of the direct drive motor of the motor pulley direct drive traction module of the underdriven traction device based on planetary gear differential mechanism and a cross-sectional view of the direct drive motor along the BB direction in (a).

[0026] Figure 7 yes Figure 1 Another schematic diagram of the underdriven traction device based on the planetary gear differential mechanism.

[0027] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1-two-input four-output underdriven traction module, 2-motor pulley direct drive traction module, 3-driver side plate, 4-wire rope, 5-one-way bearing tensioner, 6-actuator, 7-wire rope conduit, 8-harmonic brushless motor, 9-motor mounting base, 10-first bearing housing, 11-second bearing housing, 12-first pulley, 13-motor output shaft, 14-drive gear, 15-first driven gear, 16-first driven gear ring, 17-second pulley, 18-second driven gear, 19-first driven part bearing housing, 20-driven sun gear shaft, 21-second driven part bearing housing, 22-wire rope air pipe connector, 23-carbon fiber base plate, 24-planetary gear, 25-direct drive motor, 26-direct drive gear, 27-direct drive flange, 28-direct drive mechanism top plate. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0029] Please see Figure 1 , Figure 2 and Figure 7This invention provides an underdriven traction device based on a planetary gear differential mechanism. The traction device includes a two-input four-output underdriven traction module 1, a motor-driven sheave direct-drive traction module 2, and a sheave output tensioning module. The two-input four-output underdriven traction module 1 is connected to the motor-driven sheave direct-drive traction module 2, and both are connected to sheave output tensioning modules. The motor-driven sheave direct-drive traction module 2 provides forward and reverse traction forces to the actuator 6, which requires the sheave to travel back and forth. The two-input four-output underdriven traction module 1 converts the power input from two motors into a four-output drive mechanism through the proportional action of the planetary gear differential mechanism, thus changing the original two-way power source input into four-way power source output. Both the motor-driven sheave direct-drive traction module 2 and the two-input four-output underdriven traction module 1 employ sheave output tensioning modules, ensuring that the sheave maintains a regular winding and unwinding pattern during the winding process without causing tangling. The traction device can be applied in the field of hand exoskeletons. As part of the rope-driven traction structure, the motor-coil direct-drive traction module 2 can provide a power source for thumb bending and lateral swinging movements. The two-input four-output underdriven traction module 1 can drive and reproduce the coordinated movement of the four fingers of the hand, further overcoming the stroke limitations of existing underdriven mechanisms and improving traction power.

[0030] The two-input four-output underdriven traction module 1 and the motor-driven direct-drive traction module 2 are both fixed on the same carbon fiber base plate 23.

[0031] Please see Figure 3 and Figure 4 The two-input four-output underdriven traction module 1 includes two direct-drive modules and two planetary gear differential mechanisms. The two direct-drive modules are connected and arranged in the same direction. The two planetary gear differential mechanisms are respectively located on opposite sides of the direct-drive modules and are meshed with the direct-drive modules. Each direct-drive module and each of the two planetary gear differential mechanisms provides one power source output.

[0032] The two direct-drive modules are symmetrically arranged and have identical structures. Each direct-drive module includes a harmonic brushless motor 8, a motor mounting base 9, a first bearing housing 10, a second bearing housing 11, a first spool 12, a drive gear 14, and a motor output shaft 13. The first bearing housing 10 and the second bearing housing 11 are spaced apart on the carbon fiber base plate 23. The harmonic brushless motor 8 is mounted on the motor mounting base 9. The motor mounting base 9 is fixed to the first bearing housing 10 with bolts. The output port of the harmonic brushless motor 8 is connected to the motor output shaft 13 via a bolt-flange connection. A first keyway is formed on the motor output shaft 13, and a second keyway is formed inside the drive gear 14. The first and second keyways are fixed to a key fixed on the first spool 12. The two ends of the first spool 12 are respectively mounted on the first bearing housing 10 and the second bearing housing 11 via bearings.

[0033] The harmonic brushless motor 8 drives the first reel 12 to rotate via the motor output shaft 13. The first reel 12 rotates synchronously with the drive gear 14. The first reel 12 is self-driven by the motor, outputting power to the actuator 6 for motion drive. The power of the first reel 12 enables precise control of the actuator 6, which requires direct motor drive. The drive gear 14 transmits power to the driven components. The two direct drive modules share the second bearing housing 11, and each direct drive module provides a two-input, two-output power source.

[0034] The two planetary gear differential mechanisms have identical structures. Each planetary gear differential mechanism includes a second driven bearing housing 21, a first driven gear 15, a first driven ring gear 16, a second spool 17, a planetary gear 24, a second driven gear 18, a driven sun gear shaft 20, and a first driven bearing housing 19. The first and second driven bearings are spaced apart on the carbon fiber base plate 23. The first driven gear 15 and the second driven gear 18 respectively engage with the drive gears 14 of the two direct drive modules to transmit the motion of the two harmonic brushless motors 8 to the driven parts via gears. The first driven gear 15 is connected to the first driven ring gear 16 to transmit the motion of one of the two harmonic brushless motors 8 to the first driven ring gear 16, causing the first driven ring gear 16 to rotate. The two ends of the driven sun gear shaft 20 are respectively mounted on the first driven bearing housing 19 and the second driven bearing via bearings, and it passes through the first driven gear 15. The second spool 17 is mounted on the driven sun gear shaft 20 via a bearing. The second driven gear 18 is fixed to the driven sun gear shaft 20 by a key. A center gear is also fixed on the driven sun gear shaft 20. The center gear is located inside the first driven gear ring 16 and meshes with both the first driven gear ring 16 and the planetary gear 24. The middle part of the planetary gear 24 is fixedly connected to the second spool 17.

[0035] The second driven gear 18 transmits the motion of the other harmonic brushless motor 8 to the driven sun gear shaft 20 according to the gear transmission ratio. The driven sun gear shaft 20 drives the center gear to rotate. The planetary gear 24 rotates under the drive of the center gear and the first driven ring gear 16 to drive the second spool 17 to rotate. Since the rotational angular velocity of the planetary gear 24 in the planetary gear differential mechanism is proportional to the rotation of the ring gear and the sun gear (center gear), the second spool 17 and the planetary gear 24 can be fixed together to output rotational motion proportional to the two transmission mechanisms, achieving a low input and high output effect. The planetary gear differential mechanism on the other side has the same arrangement, further achieving a two-input, four-output effect.

[0036] Please see Figure 5 and Figure 6Two motor-driven direct-drive traction modules 2 are symmetrically arranged on the carbon fiber base plate 23 and have identical structures. Each motor-driven direct-drive traction module 2 includes a direct-drive motor 25, a direct-drive flange 27, and a direct-drive pulley. The direct-drive motor 25 transmits power to the direct-drive pulley via a keyway connection through the direct-drive flange 27. The direct-drive pulley has a keyway at one end connected to the motor's input power end, and the other end is fixed to the mounting plate via a bearing to transmit the direct-drive motion of the motor, which is also transmitted to the actuator 6. The motor-driven direct-drive traction module 2 is commonly used in modules requiring independent movement, such as the thumb flexion / extension and lateral swing movements of a hand exoskeleton.

[0037] Please see Figure 2 The movements of the two direct-drive spools, the two second spools 17, and the two first spools 12 are respectively connected to the corresponding actuators 6 through the spool output tensioning module, so as to transmit the movement of the spools to the actuators 6. The sheave output tensioning module includes two wire ropes 4, two wire rope 4 air pipe connectors, two wire rope guides 7, and two one-way bearing tensioning wheels 5. One end of each wire rope 4 passes through one of the one-way bearing tensioning wheels 5 and is connected to the groove of a corresponding sheave. The other end is connected to one of the wire rope 4 air pipe connectors. One end of each wire rope guide 7 is connected to the wire rope 4 air pipe connector, and the other end is connected to the actuator 6. Similarly, the other wire rope 4, wire rope guide 7, and wire rope 4 air pipe connector are connected in the same way. Specifically, one end of another wire rope 4 passes through another one-way bearing tensioning wheel 5 and is connected to the other groove of the corresponding sheave. The other wire rope 4 air pipe connector is connected to the corresponding wire rope 4 and wire rope guide 7, so that the wire rope 4 and wire rope guide 7 form a complete loop in the entire stroke circuit. During the rope winding stage, the one-way bearing tensioning wheel 5 provides resistance to the winding of the wire rope 4, ensuring that the displacement relationship remains unchanged during rope contraction. During rope unwinding, the one-way bearing tensioning wheel 5 can move in the opposite direction without obstruction, guaranteeing smooth winding and unwinding. Furthermore, the wire rope guide 7 provides external protective support for the wire rope 4 when its stroke is long and exposed. The air hose connector for the wire rope 4, connected to one side of the wire rope guide 7, provides a solution for quick-release adjustment of the wire rope 4. The two ends of the reel have different diameters, which can be adjusted to ensure unrestricted stroke in specific applications. The air hose connector for the wire rope 4 is generally fixed to the drive side plate 3 or the top plate 28 of the direct drive mechanism via a threaded connection.

[0038] The present invention also provides a hand exoskeleton, which includes a connected prosthetic hand and an underactuated traction device based on a planetary gear differential mechanism as described above. In this case, the prosthetic hand serves as the actuator 6.

[0039] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An underdriven traction device based on a planetary gear differential mechanism, characterized in that: The traction device includes a two-input four-output underdriven traction module, a motor-coil direct-drive traction module, and a coil output tensioning module. The two-input four-output underdriven traction module is connected to the motor-coil direct-drive traction module, and both are respectively connected to the coil output tensioning module. The motor pulley direct drive traction module is used to provide forward and reverse traction force to the actuator; the two-input four-output underdriven traction module is a drive mechanism that converts two input forces into four outputs through the proportional action of the planetary gear differential mechanism, so that two power inputs become four power outputs. The two-input four-output underdriven traction module includes two direct drive modules and two planetary gear differential mechanisms. The two direct drive modules are connected and arranged in the same direction. The two planetary gear differential mechanisms are respectively arranged on opposite sides of the direct drive modules and are meshed with the direct drive modules. The motor-driven sheave direct-drive traction module includes a direct-drive motor, a direct-drive flange, and a direct-drive sheave. The direct-drive motor transmits power to the direct-drive sheave via the direct-drive flange in a keyway connection. The sheave output tensioning module includes two wire ropes, two wire rope air pipe connectors, two wire rope guides, and two one-way bearing tensioning pulleys. One end of each wire rope passes through one of the one-way bearing tensioning pulleys and is connected to the groove of a corresponding sheave, while the other end is connected to one of the wire rope air pipe connectors. One end of one of the wire rope guides is connected to the wire rope air pipe connector, and the other end is connected to the actuator. One end of another wire rope passes through another one-way bearing tensioning pulley and is connected to the other groove of the corresponding sheave. The other wire rope air pipe connector connects the corresponding wire rope and the wire rope guide, so that the wire rope and the wire rope guide form a complete loop throughout the entire stroke circuit. The planetary gear differential mechanism includes a second driven bearing housing, a first driven gear, a first driven gear ring, a second spool, planetary gears, a driven sun gear shaft, and a first driven bearing housing. The first and second driven bearings are spaced apart on a carbon fiber base plate. The first and second driven gears respectively engage with the drive gears of the two direct drive modules. The first driven gear is fixedly connected to the first driven gear ring. The two ends of the driven sun gear shaft are respectively mounted on the first driven bearing housing and the second driven bearing via bearings, and pass through the first driven gear. The second spool is sleeved on the driven sun gear shaft via a bearing. The second driven gear is fixed on the driven sun gear shaft via a key. The motor-spool direct drive traction module provides a power source for thumb bending and lateral movement, and the two-input four-output underdriven traction module can reproduce the coordinated movement of the four fingers of the hand.

2. The underdriven traction device based on a planetary gear differential mechanism as described in claim 1, characterized in that: Each of the direct drive modules and each of the planetary gear differential mechanisms provides one power source output.

3. The underdriven traction device based on a planetary gear differential mechanism as described in claim 1, characterized in that: The two direct-drive modules are symmetrically arranged and have the same structure. Each direct-drive module includes a harmonic brushless motor, a motor mounting base, a first bearing housing, a second bearing housing, a first spool, a drive gear, and a motor output shaft. The first and second bearing housings are spaced apart on a carbon fiber base plate. The harmonic brushless motor is mounted on the motor mounting base. The motor mounting base is fixed to the first bearing housing. The output port of the harmonic brushless motor is connected to the motor output shaft. A first keyway is provided on the motor output shaft, and a second keyway is provided inside the drive gear. The first and second keyways are fixed to a key fixed on the first spool. The two ends of the first spool are respectively mounted on the first bearing housing and the second bearing housing via bearings.

4. The underdriven traction device based on a planetary gear differential mechanism as described in claim 3, characterized in that: The two planetary gear differential mechanisms have the same structure and are meshed with the direct drive module.

5. The underdriven traction device based on a planetary gear differential mechanism as described in claim 4, characterized in that: A center gear is also fixed on the driven sun gear shaft. The center gear is located inside the first driven gear ring and meshes with both the first driven gear ring and the planetary gear. The middle part of the planetary gear is fixedly connected to the second spool.

6. The underdriven traction device based on a planetary gear differential mechanism as described in claim 4, characterized in that: The two motor pulley direct drive traction modules are symmetrically arranged on the carbon fiber base plate and have the same structure.

7. The underdriven traction device based on a planetary gear differential mechanism as described in claim 6, characterized in that: The motion of the two direct-drive spools, the two second spools, and the two first spools is respectively connected to the corresponding actuators through the spool output tensioning module, so as to transmit the motion of the spools to the actuators.

8. A hand exoskeleton, characterized in that: The hand exoskeleton includes a connected prosthetic hand and an underactuated traction device based on a planetary gear differential mechanism as described in any one of claims 1-7.

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