Multi-degree-of-freedom hip joint mechanism

Abstract

The invention relates to the technical field of exoskeletons, in particular to a multi-degree-of-freedom hip joint mechanism which comprises a motor outer ring and a motor inner ring, two sets of positioning pins are fixedly connected to the top of the motor outer ring, a limiting block is fixedly connected to one side of the motor inner ring, and a ball bearing is slidably connected to the outer side of a transmission shaft. A self-reset spring is installed at the bottom of the connecting piece, a coating is arranged on the inner side surface of the connecting piece, and a sensing element is fixedly connected into the second hinge. The connecting piece, the transmission shaft, the ball bearing and the joint shell are arranged, the motion trail of the mechanism is highly matched with the real biomechanical characteristics of the hip joint of the human body, the problems that a traditional mechanism is rigid in motion and poor in fitting degree are solved, the positioning pin, the limiting block, the self-reset spring, the bionic coating and the sensing element are arranged, motion range protection is provided, and the reliability is high. Buffering damping and automatic resetting are achieved, and durability and smoothness are improved.

Description

Technical Field

[0001] This invention belongs to the field of exoskeleton technology, specifically relating to a multi-degree-of-freedom hip joint mechanism. Background Technology

[0002] With the increasing aging population and the growing demand for ergonomics in rehabilitation medicine, military, and industrial fields, lower limb exoskeleton technology has received widespread attention. The hip joint, as the core joint connecting the trunk and lower limbs and enabling complex three-dimensional movements, directly determines the exoskeleton's motion fit, wearing comfort, and assistive effect through its structural design. Assistive exoskeletons generally include: the lumbar frame, the hip joint mechanism, and the leg frame.

[0003] Existing hip joint mechanisms have limited degrees of freedom, typically only enabling active flexion and extension movements in the sagittal plane. They cannot adapt to the multi-dimensional passive movements of the hip joint during activities such as walking and turning, including adduction / abduction and internal / external rotation. This results in stiff and unnatural movements, causing discomfort to the wearer with prolonged use. Furthermore, they lack effective active drive capabilities and cannot provide substantial assistance to the user. Existing hip joint mechanisms also have shortcomings in load-bearing capacity, wear resistance, and environmental adaptability. Their safety designs, such as impact protection and movement limitation, are relatively simple and cannot cope with complex and ever-changing application scenarios. Therefore, we propose a multi-degree-of-freedom hip joint mechanism. Summary of the Invention

[0004] In order to overcome the above-mentioned technical problems, the present invention aims to provide a multi-degree-of-freedom hip joint mechanism to solve the problems mentioned in the background art, such as the single degree-of-freedom configuration of existing hip joint mechanisms, which leads to stiff and unnatural movement, causes discomfort to wearers after long-term use, lacks effective active driving capability, and cannot provide substantial assistance to users. Furthermore, existing hip joint mechanisms are insufficient in terms of load-bearing capacity, wear resistance, and environmental adaptability, making it difficult to cope with complex and ever-changing application scenarios.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a multi-degree-of-freedom hip joint mechanism, comprising an outer ring of a motor and an inner ring of a motor. The outer ring has eight sets of mounting holes on its top circumference. Two sets of positioning pins are fixedly connected to the top of the outer ring. The inner ring has four sets of mounting holes on its top. A limit block is fixedly connected to one side of the inner ring. A connector is mounted on the top of the inner ring. Connecting bolts are rotatably connected to the four corners of the connector. A drive shaft is rotatably connected inside the connector. A ball bearing is slidably connected to the outside of the drive shaft. A joint housing is provided outside the ball bearing. A self-resetting spring is mounted at the bottom of the connector. A coating is provided on the inner surface of the connector. A hinge is mounted on the top of the drive shaft. An elastic retaining ring is fixedly connected to the top of the hinge. A hinge is rotatably connected to one side of the hinge. A hinge pin is installed at the connection between the hinge and the hinge. A sensing element is fixedly connected inside the hinge.

[0006] Preferably, the outer ring of the motor is fixedly connected to the waist frame of the exoskeleton through the first mounting hole, and the inner ring of the motor is fixedly connected to the connector through the second mounting hole and the connecting bolt.

[0007] Preferably, the limiting block cooperates with the positioning pin to limit the rotation angle of the inner ring of the motor relative to the outer ring of the motor.

[0008] Preferably, the connector and the joint housing together constitute an outer shell with an internal spherical cavity, one end of the drive shaft is a spherical end, the spherical end extends into the spherical cavity of the outer shell and forms a clearance fit with the cavity, and the drive shaft has passive rotational freedom about at least two axes.

[0009] Preferably, the ball bearing is installed in the ball channel inside the housing and is located between the spherical end of the drive shaft and the spherical cavity wall of the housing.

[0010] Preferably, the coating is a Teflon elastomer coating, applied to the inner surface of the spherical cavity formed by the connector and the joint housing, with one end of the self-resetting spring snapped into the bottom of the drive shaft and the other end of the self-resetting spring fixedly connected to the bottom of the connector.

[0011] Preferably, the sensing element includes a gyroscope, an angular displacement sensor, and a wireless communication module.

[0012] Compared with the prior art, the beneficial effects of the present invention are:

[0013] 1. This multi-degree-of-freedom hip joint mechanism incorporates connectors, a drive shaft, ball bearings, and a joint housing. Through optimized structural layout, it highly integrates active drive and passive compliance mechanisms. The core active flexion-extension movements are assisted by a motor drive. Simultaneously, a carefully designed spherical end of the drive shaft forms a biomimetic joint pair with a precision spherical cavity composed of the connectors and the joint housing. Combined with a guiding and supporting mechanism consisting of multiple ball bearings evenly distributed circumferentially within the cavity, it achieves multi-dimensional passive compliance movements such as adduction / abduction and internal / external rotation. This "active-passive" composite degree-of-freedom design allows the mechanism to not only output controllable auxiliary torque but also flexibly adapt to lateral and rotational movements like a human joint. This ensures the mechanism's motion trajectory closely matches the actual biomechanical characteristics of the human hip joint, effectively eliminating internal interference and external constraint during movement, and solving the problems of stiffness and poor fit in traditional mechanisms.

[0014] 2. This multi-degree-of-freedom hip joint mechanism incorporates positioning pins, limiting blocks, self-resetting springs, a biomimetic coating, and sensing elements, constructing a multi-layered safety assurance and performance optimization system from physical protection to intelligent early warning. It not only provides direct protection beyond the motor's braking capacity through the interlocking of the positioning pins fixed to the outer ring of the motor and the limiting blocks fixed to the inner ring, fundamentally preventing overtravel risks caused by control system malfunctions or misoperation; it also effectively absorbs and disperses motion impacts through the biomimetic elastomer coating applied to the spherical mating surface, significantly reducing wear and noise, and provides constant return to center through the self-resetting spring connecting the drive shaft and the connecting parts. The torque enables buffering, shock absorption, and automatic reset, ensuring the smoothness and positional accuracy of the mechanism's long-term operation and improving durability and smoothness. Furthermore, by integrating sensing elements containing multi-axis motion sensors within hinge two, real-time monitoring and feedback of motion status are achieved. This provides indispensable hardware data support for the exoskeleton system to realize intelligent functions such as adaptive assist control based on motion intention recognition and fall prevention warning based on real-time posture data. It lays the hardware foundation for adaptive control and advanced safety protection, thereby comprehensively improving the mechanism's safety, reliability, environmental adaptability, and human-computer interaction level from multiple dimensions, from passive protection to active optimization. Attached Figure Description

[0015] Figure 1 This is a three-dimensional structural schematic diagram of the present invention;

[0016] Figure 2 This is an exploded view of the structure of the present invention;

[0017] Figure 3 This is a bottom view schematic diagram of the structure of the connector and hinge 2 of the present invention;

[0018] Figure 4 This is a side sectional view of the connector structure of the present invention;

[0019] Figure 5 This is a schematic diagram of the assembly process of the present invention.

[0020] In the diagram: 1. Motor outer ring; 11. Mounting hole one; 12. Locating pin; 2. Motor inner ring; 21. Mounting hole two; 22. Limiting block; 3. Connecting piece; 31. Connecting bolt; 32. Drive shaft; 33. Ball bearing; 34. Joint housing; 35. Self-resetting spring; 36. Coating; 4. Hinge one; 41. Elastic retaining ring; 42. Hinge two; 43. Hinge pin; 44. Sensing element. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see Figure 1-5 One embodiment provided by the present invention:

[0023] A multi-degree-of-freedom hip joint mechanism includes an outer motor ring 1 and an inner motor ring 2. The outer motor ring 1 has eight sets of mounting holes 11 on its top circumference. Two sets of locating pins 12 are fixedly connected to the top of the outer motor ring 1. The inner motor ring 2 has four sets of mounting holes 21 on its top. A limit block 22 is fixedly connected to one side of the inner motor ring 2. A connector 3 is mounted on the top of the inner motor ring 2. Connecting bolts 31 are rotatably connected to the four corners of the connector 3. A drive shaft 32 is rotatably connected inside the connector 3. A ball bearing 33 is slidably connected to the outside of the drive shaft 32. A joint housing 34 is provided on the outside of the ball bearing 33. A self-resetting spring 35 is mounted on the bottom of the connector 3. The inner surface of the connector 3 is provided with… The coating 36 has a hinge 4 mounted on the top of the drive shaft 32. An elastic retaining ring 41 is fixedly connected to the top of hinge 4. A hinge 42 is rotatably connected to one side of hinge 4. A hinge pin 43 is installed at the connection between hinge 4 and hinge 42. A sensing element 44 is fixedly connected inside hinge 42. A connector 3, drive shaft 32, ball bearing 33, and joint housing 34 are included. Through optimized structural layout, active drive and passive compliance mechanisms are highly integrated. The core flexion and extension active movements are achieved through motor drive to provide assistance. Simultaneously, a carefully designed spherical end of the drive shaft 32 forms a biomimetic joint pair with a precision spherical cavity composed of the connector 3 and joint housing 34. Combining a guiding and supporting mechanism consisting of multiple ball bearings 33 evenly distributed circumferentially within the cavity, passive compliant movements in multiple dimensions, such as adduction / abduction and internal / external rotation, are achieved. This "active-passive" composite degree of freedom design allows the mechanism to not only output controllable auxiliary torque but also adapt flexibly to lateral and rotational movements like a human joint. This ensures that the mechanism's motion trajectory closely matches the actual biomechanical characteristics of the human hip joint, effectively eliminating internal interference and external constraint during movement. It solves the problems of stiff movement and poor fit in traditional mechanisms. The design incorporates positioning pins 12, limit blocks 22, self-resetting springs 35, biomimetic coatings 36, and sensing elements 44, constructing a system that integrates physical protection with intelligent... The multi-layered safety assurance and performance optimization system with early warning capability not only provides direct protection against movement beyond the motor's braking capacity through the interlocking of the positioning pin 12 fixed on the outer ring 1 of the motor and the limiting block 22 fixed on the inner ring 2 of the motor, fundamentally preventing the risk of overtravel caused by control system failure or misoperation; it also effectively absorbs and disperses motion impact through the biomimetic elastomer coating 36 applied to the spherical mating surface, significantly reducing wear and noise, and the constant restoring torque provided by the self-resetting spring 35 connecting the transmission shaft 32 and the connecting part 3, achieving buffering and shock absorption and automatic reset, together ensuring the smoothness and positional accuracy of the mechanism's long-term operation, and improving durability and smoothness;Furthermore, by integrating a sensing element 44 containing multi-axis motion sensors within hinge 2 42, real-time monitoring and feedback of motion status are achieved. This provides indispensable hardware data support for the exoskeleton system to realize intelligent functions such as adaptive assist control based on motion intention recognition and fall prevention warning based on real-time posture data. It lays the hardware foundation for adaptive control and advanced safety protection, thereby comprehensively improving the mechanism's safety, reliability, environmental adaptability, and human-computer interaction level from multiple dimensions, from passive protection to active optimization.

[0024] Furthermore, the outer ring 1 of the motor is fixedly connected to the waist frame of the exoskeleton through mounting hole 11, and the inner ring 2 of the motor is fixedly connected to the connector 3 through mounting hole 21 and connecting bolt 31, thereby establishing an efficient and slip-free stable power transmission path from the external power source to the joint body between the motor stator and rotor, and between the rotor and the motion execution component.

[0025] Furthermore, the limiting block 22 cooperates with the positioning pin 12. The limiting block 22 is rigidly connected to the radial side of the inner ring 2 of the motor, while the two cylindrical positioning pins 12 are symmetrically fixed on the top plane of the outer ring 1 of the motor. The two form an interference pair in space to limit the rotation angle of the inner ring 2 of the motor relative to the outer ring 1 of the motor. When the mechanism rotates to the preset limit position, the side of the limiting block 22 will collide with the positioning pin 12 to form a physical stop, which constitutes the final and most reliable first mechanical safety barrier to prevent excessive movement.

[0026] Furthermore, the connector 3 and the joint housing 34 together constitute an outer shell with a spherical cavity inside. One end of the drive shaft 32 is a spherical end, which extends into the spherical cavity of the outer shell and forms a clearance fit with the cavity. This allows the drive shaft 32 to have a passive rotational degree of freedom around at least two axes, thus simulating the adduction, abduction, internal and external rotation activities of the human hip joint in addition to flexion and extension, and realizing the movement of the mechanism in the non-driving direction.

[0027] Furthermore, the ball bearing 33 is installed in the ball channel inside the housing and is located between the spherical end of the drive shaft 32 and the spherical cavity wall of the housing. The ball bearing 33 is used to constrain the rotation of the drive shaft 32 along its own axis, that is, the torsion around the center line of the drive shaft 32 rod, while allowing it to achieve passive movements of inward / outward and internal / external rotation. The torque transmission function and the multi-degree-of-freedom decoupling function are integrated into the same set of structures, so that the drive shaft 32 can obtain multi-directional swing freedom while ensuring the effective transmission of torque along its axial direction.

[0028] Furthermore, coating 36 is a Teflon elastomer coating, applied to the inner surface of the spherical cavity formed by connector 3 and joint housing 34. One end of self-resetting spring 35 is snapped into the bottom of drive shaft 32, and the other end of self-resetting spring 35 is fixedly connected to the bottom of connector 3. Self-resetting spring 35 is used to provide a reverse elastic restoring force after drive shaft 32 completes passive degree of freedom movement, so that it automatically returns to the center position. The two work together. Coating 36 mainly reduces friction and wear on the contact surface and absorbs high-frequency micro-vibrations, while self-resetting spring 35 mainly overcomes gaps and maintains the stability of return position after movement. They respectively play a dual optimization role of reducing friction and wear and impact, and eliminating movement gaps and automatically returning to the center position.

[0029] Furthermore, the sensing element 44 includes a gyroscope, an angle displacement sensor, and a wireless communication module, which are used to collect the posture, angle, speed, and acceleration data of the hip joint mechanism during the movement process, and transmit the data collected by the sensing element 44 to an external controller.

[0030] Working principle: During operation, the inner ring 2 of the motor rotates under the precise command of the external control system. Its rotational torque is transmitted losslessly to the connecting member 3 through the connecting bolt 31. As the core hub of the entire kinematic chain, the rotation of the connecting member 3 directly drives the transmission shaft 32 fixedly connected to it, as well as the hinge 4 and hinge 42 at the top, causing them to rotate together around the motor axis (i.e., the flexion and extension axis of the hip joint). This process constitutes the active flexion and extension drive degree of freedom of the hip joint mechanism, which can output a controllable auxiliary torque according to the preset algorithm or the wearer's intention, providing necessary assistance for the wearer to complete actions such as walking, climbing stairs, and sitting up. This effectively distributes or enhances lower limb strength. When the human body performs complex movements requiring lateral movement (such as stepping left or right, obstacle avoidance) or pelvic rotation (such as turning, twisting the waist), the body's natural movement is transmitted through the thigh part of the exoskeleton, via hinge 2 42 and hinge pin 43, and finally to hinge 1 4 and drive shaft 32. At this time, the force will cause the precision spherical end of the lower end of the drive shaft 32 to produce corresponding inward or outward yaw, as well as internal or external rotation, within the spherical cavity formed by the connector 3 and the joint housing 34, whose inner wall is coated with a low-friction biomimetic coating 36. Multiple ball bearings 33, evenly distributed around the circumference, are used at this time. They played a crucial guiding and load-bearing role, precisely constraining the undesirable torsion of the drive shaft 32 around its own axis, ensuring the independence of the active drive torque transmission path; at the same time, with their low-resistance rolling characteristics, they allowed and guided the spherical end to slide and rotate smoothly in multiple directions within the cavity. This enabled the mechanism to passively and with low resistance achieve multi-dimensional compliant movements such as adduction, abduction, internal rotation, and external rotation. This allows the mechanism to flexibly adapt to and follow the complex movements of the human body, much like the human hip joint, avoiding the rigid restrictions and interference of exoskeleton mechanisms on natural human movements. This significantly improves wearing comfort and the naturalness of movement, enhancing the overall comfort and performance of the device. During the movement, the sensing element 44 embedded in the hinge 42 continuously collects high-frequency data. Its integrated gyroscope and angular displacement sensor monitor and record the active flexion and extension angle, angular velocity, and the attitude changes, motion angles, and accelerations of each passive degree of freedom (adduction / extension, internal rotation / external rotation) in real time and synchronously. These multi-dimensional motion data are sent to the upper controller in real time through the wireless communication module. At the same time, the multiple safety protection and performance optimization mechanisms inside the mechanism work together: the biomimetic coating 36 continuously reduces the friction coefficient between the spherical mating surfaces, effectively absorbs micro-impacts and vibrations, ensures smooth movement, and extends the life of the parts.The self-resetting spring 35 always applies an elastic restoring force to the transmission shaft 32, pointing towards the initial neutral position. This ensures that the mechanism can automatically and quickly return to its original position after passive movement ends, eliminating play or clearance that may occur due to long-term use and maintaining the consistency and accuracy of movement. When the active flexion and extension movement reaches the preset limit angle due to any reason (such as control abnormality or external impact), the limiting block 22 fixed on the inner ring 2 of the motor will rigidly collide with the positioning pin 12 fixed on the outer ring 1 of the motor, forming a mechanical stop independent of the electrical control. This forcibly limits the range of motion, providing the wearer with the most reliable physical safety protection and preventing potential injuries caused by excessive flexion or extension of the joint.

[0031] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A multi-degree-of-freedom hip joint mechanism, comprising an outer motor ring (1) and an inner motor ring (2), characterized in that: The outer ring (1) of the motor has eight sets of mounting holes (11) on its top circumference. Two sets of positioning pins (12) are fixedly connected to the top of the outer ring (1). The inner ring (2) of the motor has four sets of mounting holes (21) on its top. A limit block (22) is fixedly connected to one side of the inner ring (2). A connector (3) is installed on the top of the inner ring (2). Connecting bolts (31) are rotatably connected to the four corners of the connector (3). A drive shaft (32) is rotatably connected inside the connector (3). A ball bearing (33) is slidably connected to the outside of the drive shaft (32). The ball bearing (33) is provided with a joint housing (34) on its outer side. The bottom of the connector (3) is provided with a self-resetting spring (35). The inner surface of the connector (3) is provided with a coating (36). The top of the drive shaft (32) is provided with a hinge one (4). The top of the hinge one (4) is fixedly connected with an elastic retaining ring (41). The hinge one (4) is rotatably connected to one side of the hinge one (4). The hinge one (4) and the hinge two (42) are connected with a hinge pin (43). The inside of the hinge two (42) is fixedly connected with a sensing element (44).

2. The multi-degree-of-freedom hip joint mechanism according to claim 1, characterized in that: The outer ring (1) of the motor is fixedly connected to the waist frame of the exoskeleton through the first mounting hole (11), and the inner ring (2) of the motor is fixedly connected to the connector (3) through the second mounting hole (21) and the connecting bolt (31).

3. The multi-degree-of-freedom hip joint mechanism according to claim 1, characterized in that: The limiting block (22) cooperates with the positioning pin (12) to limit the rotation angle of the inner ring (2) of the motor relative to the outer ring (1) of the motor.

4. The multi-degree-of-freedom hip joint mechanism according to claim 1, characterized in that: The connector (3) and the joint housing (34) together constitute an outer shell with a spherical cavity inside. One end of the drive shaft (32) is a spherical end, which extends into the spherical cavity of the outer shell and forms a clearance fit with the cavity. The drive shaft (32) has passive rotational freedom about at least two axes.

5. A multi-degree-of-freedom hip joint mechanism according to claim 4, characterized in that: The ball bearing (33) is installed in the ball channel inside the housing and is located between the spherical end of the drive shaft (32) and the spherical cavity wall of the housing.

6. A multi-degree-of-freedom hip joint mechanism according to claim 1, characterized in that: The coating (36) is a Teflon elastomer coating, which is applied to the inner surface of the spherical cavity formed by the connector (3) and the joint housing (34). One end of the self-resetting spring (35) is snapped into the bottom of the drive shaft (32), and the other end of the self-resetting spring (35) is fixedly connected to the bottom of the connector (3).

7. A multi-degree-of-freedom hip joint mechanism according to claim 1, characterized in that: The sensing element (44) includes a gyroscope, an angular displacement sensor, and a wireless communication module.

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