Unilateral parallel connection rod type ankle structure and robot

Abstract

The invention provides a unilateral parallel connecting rod type ankle structure and a robot, and belongs to the technical field of robots. The problems that due to the fact that an existing humanoid robot ankle mechanism adopts a symmetrical double-connecting-rod or direct-driving structure, the occupied transverse space is large, and the rotational inertia is high are solved. The device comprises a shank part, a long connecting rod, a short connecting rod and a sole plate, a first driver and a second driver are arranged on the shank part, the output end of the first driver is connected with a first output flange connecting rod, the output end of the second driver is connected with a second output flange connecting rod, and the first output flange connecting rod is connected with the long connecting rod. The second output flange connecting rod is connected with a short connecting rod, a sole plate connecting rod is installed on the sole plate and provided with two connecting ends, the two connecting ends are connected with a long connecting rod and a short connecting rod respectively, the long connecting rod and the short connecting rod are both arranged on the outer side of a shank part, and the lower portion of the shank part is connected with the sole plate through a cross bearing. The robot ankle structure is mainly used for robot ankle structures.

Description

Technical Field

[0001] The present invention belongs to the technical field of robots, and in particular relates to a unilateral parallel connecting rod ankle structure and a robot. Background Art

[0002] The design of a humanoid robot's ankle mechanism directly impacts its mobility and terrain adaptability. Current mainstream solutions include three main types of structures: The first is a single-axis direct-drive configuration, where a motor directly drives the ankle to achieve pitch or roll motion. While this solution is simple, its output torque is limited, making it difficult to meet the dynamic support requirements in complex terrain. The second is a symmetrical double-link structure (parallel four-bar mechanism), which improves mechanical performance by symmetrically arranging links and revolute pairs on both sides of the ankle. However, this design suffers from bulky structure, complex assembly, and dispersed weight distribution. The third is a direct-drive or harmonic reducer solution, which generally suffers from high inertia, high space utilization, and difficult wiring.

[0003] The existing structures mentioned above generally suffer from the following drawbacks: First, the ankle's overall thickness is too large, resulting in low utilization of the leg's lateral space, limiting the robot's ability to maneuver in confined environments. Second, the symmetrical layout requires redundant connecting rods and bearings, significantly increasing processing costs and maintenance. Third, the dispersed center of gravity increases the moment of inertia, weakening the dynamic response speed of gait adjustment. Finally, the spatial separation of the drive components and connecting rods results in a lengthy power transmission path, reducing energy conversion efficiency. Therefore, a new ankle mechanism that combines compactness, lightweightness, and high responsiveness is urgently needed to overcome the bottlenecks of existing technologies. Summary of the Invention

[0004] In view of this, the present invention aims to propose a unilateral parallel-link ankle structure and robot to solve the problems of large lateral space occupation, high rotational inertia, low power transmission efficiency and complex assembly and maintenance caused by the use of symmetrical double-link or direct drive structure in the existing humanoid robot ankle mechanism.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solutions: a unilateral parallel link ankle structure, which includes a calf member, a long link, a short link and a sole plate, the calf member is provided with a first driver and a second driver, the output end of the first driver is connected to the first output flange link, the output end of the second driver is connected to the second output flange link, the first output flange link is connected to the long link, the second output flange link is connected to the short link, a sole plate link is installed on the sole plate, the sole plate link has two connecting ends, the two connecting ends are respectively connected to the long link and the short link, the long link and the short link are both arranged on the outside of the calf member, and the lower part of the calf member is connected to the sole plate through a cross bearing.

[0006] Furthermore, both ends of the long connecting rod and the short connecting rod are provided with radial spherical bearings, and the radial spherical bearings are divided into a first radial spherical bearing, a second radial spherical bearing, a third radial spherical bearing and a fourth radial spherical bearing according to the connection position. One end of the long connecting rod is connected to the first output flange connecting rod through the first radial spherical bearing, and the other end is connected to the sole plate connecting rod through the second radial spherical bearing. One end of the short connecting rod is connected to the second output flange connecting rod through the third radial spherical bearing, and the other end is connected to the sole plate connecting rod through the fourth radial spherical bearing.

[0007] Furthermore, the cross bearing has two orthogonal rotation axes, wherein the two ends of one of the orthogonal rotation axes are respectively the first connection end and the second connection end, and the two ends of the other orthogonal rotation axis are respectively the third connection end and the fourth connection end, the first connection end and the second connection end are connected to the lower part of the calf member, and the third connection end and the fourth connection end are connected to the sole of the foot.

[0008] Furthermore, two ankle rolling connectors are installed on the sole of the foot, and the two ankle rolling connectors are respectively connected to the third connecting end and the fourth connecting end of the cross bearing.

[0009] Furthermore, the lower part of the calf member connects the first connecting end and the second connecting end of the cross bearing to the calf member through a calf bearing lock.

[0010] Furthermore, the upper portion of the calf member is connected to the inner thigh member via a third driver.

[0011] Furthermore, the first driver, the second driver and the third driver are all servo motors.

[0012] Furthermore, the long connecting rod and the short connecting rod are made of multi-faceted 45 steel.

[0013] Furthermore, the calf member is made of 6061 aluminum alloy.

[0014] The present invention also provides a robot, which uses any one of the above-mentioned unilateral parallel connecting rod ankle structures.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention provides a unilateral parallel-link ankle structure and a robot using such an ankle structure, which has a compact structure and optimizes space. By centrally integrating the parallel connecting rod, driver and corresponding transmission components on the same side plane of the calf, the lateral size of the ankle is significantly reduced. This layout frees up space on the other side of the leg, provides installation conditions for sensor wiring or protective housing, effectively improves the robot's passability in restricted scenarios such as narrow passages and elevators, and avoids structural interference. The compact coplanar transmission design shortens the power transmission path, eliminates shaft redundancy, and enhances the real-time response of the joints. The unilateral layout significantly reduces the lateral width of the ankle structure, making the entire leg line more slender and more suitable for movement in narrow spaces such as office environments, carriages, elevators, etc., leaving more space for robot leg wiring, shell packaging, etc.

[0016] The unilateral parallel-link ankle structure and the robot using this ankle structure described in the present invention have been improved in terms of lightweight and dynamic performance. Redundant symmetrical connecting rods, bearings and other structures are removed to reduce the weight of the entire machine, reduce the swing inertia of the robot during walking and jumping, reduce the motor load, and improve battery life and energy utilization. The redundant connecting rods and bearing components in the traditional mirror-symmetrical leg structure are streamlined, and the material optimization of the 6061 aluminum alloy skeleton and the multi-section steel connecting rod is combined to achieve overall weight reduction. The concentrated distribution of the center of gravity reduces the moment of inertia and greatly improves the dynamic response speed of gait adjustment. The weight-reducing and efficiency-enhancing design reduces the motor load and directly extends the battery life. The legs of existing robots are mostly mirror-symmetrical structures, and two sets of molds are required for mold opening. However, the components on the two legs of this application are completely identical, so only one set of molds is required, and the processing cost is low.

[0017] The unilateral parallel-link ankle structure and the robot using the ankle structure described in the present invention have better torque efficiency and structural stability. Torque amplification is achieved through the parallel-link structure, the motor output is more effective, the structural rigidity is high, the output is stable, and it is not easy to vibrate or deform. The support of the sole of the foot during landing is more stable, which helps dynamic balance control. The parallel four-bar mechanism can amplify the output torque of the motor and, combined with the high torsional stiffness of the multi-faceted steel connecting rod, ensure the stability of force transmission under complex terrain. The multi-degree-of-freedom hinge system composed of a cross bearing and a radial spherical bearing eliminates the motion interference caused by the cumulative error of the assembly, improves the power transmission efficiency, and the support rigidity is better than the existing solution.

[0018] The unilateral parallel-link ankle structure and the robot using this ankle structure described in the present invention have improved terrain adaptability and foot compliance. The cross bearing + radial spherical bearing combination provides multi-degree-of-freedom flexibility, which can better adapt to complex scenarios such as uneven ground, slopes, and soft ground, and is conducive to improving the natural gait and landing safety of the entire machine. By combining the cross bearing with orthogonal rotational degrees of freedom with the flexible compensation capability of the radial spherical bearing, the sole of the foot has active pitch and roll adjustment, which can reliably adapt to slopes, soft ground and irregular road surfaces. The impact force is evenly dispersed by the parallel connecting rod, the dynamic support stability is improved, and the risk of motion imbalance is significantly reduced.

[0019] The unilateral parallel connecting rod ankle structure and the robot using this ankle structure described in the present invention are manufactured in a modular manner, with clear structural divisions and each part having a good modular interface. The connecting rods, motors, soles, etc. can be replaced and debugged independently, which is conducive to mass production, standardized management and later maintenance. The subsystems such as the output flange and the calf part, the long and short connecting rods and the soles adopt standardized mechanical interfaces such as screw flanges and / or latch locking to achieve plug-and-play of functional modules. The replacement time of key components is shortened, the efficiency is improved compared to traditional structures, and it is compatible with flexible configurations of motors with different power and connecting rod sizes, supporting the rapid transplantation and application of multiple types of humanoid robot platforms. The solution has good scalability and compatibility. The connecting rod length, motor type, number of degrees of freedom, etc. can be adjusted according to specific needs. It is easy to transplant to humanoid robot systems of different sizes or functions such as lightweight, bionic, and service types. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings: Figure 1 This is a schematic diagram of the three-dimensional structure of a unilateral parallel connecting rod ankle structure according to the present invention; Figure 2 This is a schematic diagram of the outer plane structure of a unilateral parallel connecting rod ankle structure according to the present invention; Figure 3 This is a schematic diagram of the medial plane structure of a unilateral parallel connecting rod ankle structure according to the present invention; Figure 4 This is a schematic diagram of the three-dimensional structure of the connection between the calf member and the sole of the foot according to the present invention; Figure 5 This is a schematic diagram of the three-dimensional structure of the calf member according to the present invention; Figure 6 This is a schematic diagram of the three-dimensional structure of the first output flange connecting rod according to the present invention; Figure 7 This is a schematic diagram of the three-dimensional structure of the long connecting rod according to the present invention; Figure 8 This is a schematic diagram of the three-dimensional structure of the radial spherical plain bearing according to the present invention; Figure 9 This is a schematic diagram of the three-dimensional structure of the foot plate connecting rod according to the present invention; Figure 10 This is a schematic diagram of the three-dimensional structure of the cross bearing according to the present invention; Figure 11 This is a schematic diagram of the three-dimensional structure of the ankle rolling connector according to the present invention; Figure 12 This is a schematic diagram of the three-dimensional structure of the calf bearing lock according to the present invention; In the picture: 1- calf part, 2- first output flange connecting rod, 3- second output flange connecting rod, 4- long connecting rod, 5- short connecting rod, 6- centripetal spherical bearing, 7- sole plate connecting rod, 8- sole plate, 9- first drive, 10- second drive, 11- cross bearing, 12- ankle roll connector, 13- calf bearing lock, 14- inner thigh part, 15- third drive. DETAILED DESCRIPTION

[0021] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely explain the technical solutions in the embodiments of the present invention. It should be noted that the embodiments of the present invention and the features therein can be combined with each other in the absence of conflict, and the embodiments described are only part of the embodiments of the present invention, not all of the embodiments.

[0022] See also Figure 1-12 Describing this embodiment, a unilateral parallel link ankle structure includes a calf member 1, a long link 4, a short link 5 and a sole plate 8, wherein the calf member 1 is provided with a first driver 9 and a second driver 10, the output end of the first driver 9 is connected to the first output flange link 2, the output end of the second driver 10 is connected to the second output flange link 3, the first output flange link 2 is connected to the long link 4, the second output flange link 3 is connected to the short link 5, a sole plate link 7 is installed on the sole plate 8, the sole plate link 7 has two connecting ends, the two connecting ends are respectively connected to the long link 4 and the short link 5, the long link 4 and the short link 5 are both arranged on the outside of the calf member 1, and the lower part of the calf member 1 is connected to the sole plate 8 through a cross bearing 11.

[0023] In this embodiment, radial spherical bearings 6 are provided at both ends of the long connecting rod 4 and the short connecting rod 5. All the radial spherical bearings 6 have the same structure. Due to different installation positions, the radial spherical bearings 6 are divided into a first radial spherical bearing, a second radial spherical bearing, a third radial spherical bearing and a fourth radial spherical bearing. One end of the long connecting rod 4 is connected to the first output flange connecting rod 2 through the first radial spherical bearing, and the other end is connected to the sole plate connecting rod 7 through the second radial spherical bearing. One end of the short connecting rod 5 is connected to the second output flange connecting rod 3 through the third radial spherical bearing, and the other end is connected to the sole plate connecting rod 7 through the fourth radial spherical bearing.

[0024] In this embodiment, the cross bearing 11 has two orthogonal rotation axes, one of which has a first connection end and a second connection end, and the other has a third connection end and a fourth connection end. The first connection end and the second connection end are connected to the lower portion of the calf member 1, and the third connection end and the fourth connection end are connected to the sole plate 8. Preferably, two ankle roll connectors 12 are mounted on the sole plate 8, and the two ankle roll connectors 12 are connected to the third connection end and the fourth connection end of the cross bearing 11, respectively. Preferably, the lower portion of the calf member 1 connects the first and second connection ends of the cross bearing 11 to the calf member 1 via a calf bearing lock 13.

[0025] The upper portion of the calf member 1 in this embodiment is connected to the inner thigh member 14 via a third actuator 15. The first, second, and third actuators 9, 10, and 15 are all DM series servo motors. These motors support both position and torque control modes and are equipped with a dual encoder system, enabling high-precision position feedback and force control, meeting the high response speed and accuracy requirements of parallel configurations. The motors are connected to the output connecting rod via a standard flange, facilitating rapid assembly and modular replacement.

[0026] The long connecting rod 4 and the short connecting rod 5 described in this embodiment serve as the core load-bearing components of the parallel mechanism, and a multi-faceted model of 45 steel is used as the material. This steel has good strength and toughness, and is suitable for withstanding high-frequency dynamic loads and complex terrain impacts. At the same time, the multi-faceted cross-section improves its torsional rigidity, so that the connecting rod has stronger structural stability during posture adjustment and ground support. The material of the calf part 1 is 6061 aluminum alloy, which is a lightweight and high-strength material widely used in robot structural parts. It has good processability and strength-to-weight ratio, and is suitable for use as a leg skeleton and support member. This material not only helps to reduce the weight of the entire machine, but also makes it easy to achieve modular manufacturing through CNC processing.

[0027] In one embodiment, the lower leg member 1 forms the upper body of the structure and is provided with a location for connecting the thigh module and mounting the drive motor. The first and second output flange connecting rods 2 and 3 are disposed on the lower leg member 1 and connected to the output shaft of the motor, which transmits power to the output flange connecting rods. The long connecting rod 4 and the short connecting rod 5 are respectively connected to the first and second output flange connecting rods 2 and 3 via radial spherical bearings 6. The lower ends of the long connecting rod 4 and the short connecting rod 5 are connected to the foot plate connecting rod 7, forming a parallel four-bar mechanism for transmitting force and controlling posture during movement. The radial spherical bearings 6 provide a flexible articulation with multiple degrees of freedom, allowing the long connecting rod 4 and the short connecting rod 5 to rotate in multiple directions. The two connecting ends of the foot plate connecting rod 7 are connected to the lower ends of the long connecting rod 4 and the short connecting rod 5 via radial spherical bearings 6. As the output ends of the parallel mechanism, the foot plate 8 is driven to produce pitch or roll motion. The foot plate 8 is the end component that contacts the ground, supporting the entire machine's weight and mechanically interacting with the external terrain. The cross bearing 11, the core component of the ankle roll joint, is a multi-degree-of-freedom revolute pair located within the ankle roll connector 12. It features two orthogonal axes of rotation, enabling compound rotation of the sole plate 8 in two directions (i.e., pitch and roll). The ankle roll connector 12 is located between the sole plate 8 and the sole plate connecting rod 7 and is connected to the sole plate 8 via the cross bearing 11, enabling roll position adjustment. The calf bearing lock 13 is used to lock or pre-tighten the bearing assembly between the calf member 1 and the cross bearing 11, ensuring precise structural positioning and smooth movement.

[0028] This embodiment is a robot that uses the unilateral parallel-link ankle structure described in any of the above embodiments to form a bipedal robot. Other multi-legged robots can also use the above unilateral parallel-link ankle structure.

[0029] The specific embodiments of the present invention disclosed above are intended only to help illustrate the present invention. The specific embodiments do not describe all details in detail, nor do they limit the invention to the specific embodiments described. Numerous modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention.

Claims

1. A unilateral parallel link ankle structure, characterized by: It comprises a calf member (1), a long connecting rod (4), a short connecting rod (5) and a foot sole (8). The calf member (1) is provided with a first driver (9) and a second driver (10). The output end of the first driver (9) is connected to the first output flange connecting rod (2), the output end of the second driver (10) is connected to the second output flange connecting rod (3), the first output flange connecting rod (2) is connected to the long connecting rod (4), and the second output flange connecting rod (3) is connected to the short connecting rod (5). A foot sole connecting rod (7) is installed on the foot sole (8). The foot sole connecting rod (7) has two connecting ends, and the two connecting ends are respectively connected to the long connecting rod (4) and the short connecting rod (5). The long connecting rod (4) and the short connecting rod (5) are both provided on the outside of the calf member (1). The lower part of the calf member (1) is connected to the foot sole (8) through a cross bearing (11).

2. The unilateral parallel link ankle structure according to claim 1, characterized in that: Both ends of the long connecting rod (4) and the short connecting rod (5) are provided with radial joint bearings (6), and the radial joint bearings (6) are divided into a first radial joint bearing, a second radial joint bearing, a third radial joint bearing and a fourth radial joint bearing according to the connection position. One end of the long connecting rod (4) is connected to the first output flange connecting rod (2) through the first radial joint bearing, and the other end is connected to the sole plate connecting rod (7) through the second radial joint bearing. One end of the short connecting rod (5) is connected to the second output flange connecting rod (3) through the third radial joint bearing, and the other end is connected to the sole plate connecting rod (7) through the fourth radial joint bearing.

3. The unilateral parallel link ankle structure according to claim 1, characterized in that: The cross bearing (11) has two orthogonal rotation axes, wherein the two ends of one of the orthogonal rotation axes are respectively a first connection end and a second connection end, and the two ends of the other orthogonal rotation axis are respectively a third connection end and a fourth connection end, wherein the first connection end and the second connection end are connected to the lower part of the calf member (1), and the third connection end and the fourth connection end are connected to the sole plate (8).

4. The unilateral parallel link ankle structure according to claim 3, characterized in that: Two ankle rolling connectors (12) are installed on the sole plate (8), and the two ankle rolling connectors (12) are respectively connected to the third connecting end and the fourth connecting end of the cross bearing (11).

5. The unilateral parallel link ankle structure according to claim 3, characterized in that: The lower part of the calf member (1) connects the first connecting end and the second connecting end of the cross bearing (11) to the calf member (1) via a calf bearing lock (13).

6. The unilateral parallel link ankle structure according to claim 1, characterized in that: The upper part of the calf member (1) is connected to the inner thigh member (14) via a third driver (15).

7. The unilateral parallel link ankle structure according to claim 6, characterized in that: The first driver (9), the second driver (10) and the third driver (15) are all servo motors.

8. The unilateral parallel link ankle structure according to claim 1, characterized in that: The long connecting rod (4) and the short connecting rod (5) are made of multi-faceted 45 steel.

9. The unilateral parallel link ankle structure according to claim 1, characterized in that: The material of the shank member (1) is 6061 aluminum alloy.

10. A robot, characterized in that: The robot uses the unilateral parallel link ankle structure according to any one of claims 1 to 9.

Images