Active ankle magnetic foot device and walking method suitable for legged robot

Abstract

The application discloses a kind of active ankle magnetic foot devices and walking methods suitable for foot robot, the device includes foot limb connecting seat, motor drive mechanism, transmission mechanism, hinged seat, connecting mechanism and foot end.Foot limb connecting seat is used to connect robot foot limb;Motor drive mechanism includes motor, and power is output through rotor flange;Transmission mechanism passes through driving wheel assembly, driven wheel assembly to transmit power;Hinged seat is fixedly arranged at the bottom of motor drive mechanism, and is used to hinge connecting mechanism.Connecting mechanism includes cross shaft, connecting seat, elastic member and connecting screw rod, the cross shaft is connected with driven wheel assembly with horizontal shaft, and both ends are rotatably connected with hinged seat, longitudinal shaft is rotatably connected with connecting seat with both ends, elastic member is arranged between connecting seat and hinged seat, and connecting screw rod is fixedly connected with foot end.The device of the application can actively control pitch angle, passively adapt side swing angle, realize the compliant attachment of contact surface, and meet the needs of foot end lightweight and compactness.

Description

Technical Field

[0001] This invention belongs to the field of legged robot technology, and more specifically, relates to an active ankle joint magnetic foot device and walking method suitable for legged robots. Background Technology

[0002] The ankle joint is a crucial joint connecting the lower leg and foot of a quadruped robot. It plays a vital role in foot posture adjustment, ground contact stability, and overall leg mechanical performance. A well-designed ankle joint can enhance the robot's adaptability to complex terrain and optimize the force distribution and energy utilization efficiency of the entire leg joint. Currently, the mainstream quadruped robot foot end uses a passive contact structure similar to flexible rubber pads. While this can achieve a certain degree of terrain conformity through material elasticity, the foot posture is uncontrollable. When operating on complex terrain, inclined surfaces, or ferromagnetic surfaces, problems such as insufficient contact area and force imbalance can easily occur, thereby increasing the robot's joint energy consumption and mechanical wear.

[0003] To improve the drawbacks of passive contact structures, existing technologies have proposed multi-degree-of-freedom active drive ankle joint structure solutions, such as the dual-degree-of-freedom active ankle joint designed in patent CN118144897A, which drives pitch and lateral swing motions separately through different motors, thus achieving motion decoupling; patent CN108974172A combines a lead screw transmission unit with a double linkage parallel mechanism to achieve active adjustment of the pitch and flip of the foot support plate. However, the above solutions still have obvious defects: (1) In patent CN118144897A, the ankle joint transmission chain is long and the cumulative error is large. The crank swing requires extra space, and the multi-motor design increases the system mass, inertia and control complexity; (2) In patent CN108974172A, the ankle joint structure is complex and there are many parts, making assembly and maintenance difficult. The lead screw transmission has a large equivalent inertia, which limits the dynamic response capability; (3) Both types of solutions are difficult to achieve lightweight and compact design of the end of the leg.

[0004] Therefore, there is an urgent need for an active ankle joint suitable for legged robots that can rationally allocate active and passive degrees of freedom, and achieve a compact and lightweight structure while meeting the requirements for precise control of foot posture. Summary of the Invention

[0005] To address the challenges of balancing structural complexity, reliability, and lightweight design in the ankle joints of existing quadruped robots, this invention provides an active ankle joint magnetic foot device and walking method suitable for legged robots to solve these problems.

[0006] To achieve the above objectives, the present invention provides an active ankle joint magnetic foot device suitable for legged robots, comprising a foot limb connecting seat connected to the robot's foot; a motor drive mechanism fixedly disposed on the side of the foot limb connecting seat, including a motor mounting base and a motor, wherein the motor outputs power through a rotor flange; a transmission mechanism disposed on the other side of the motor drive mechanism, including a driving wheel assembly and a driven wheel assembly, wherein the driving wheel assembly transmits power to the driven wheel assembly at its bottom; a hinge seat disposed at the bottom of the motor mounting base, which is formed together with the foot limb connecting seat and the motor mounting base, and has a U-shaped structure; and a connection mechanism hinged to the hinge seat, comprising a cross shaft, a connecting seat, an elastic element, and a connecting screw, wherein the cross shaft includes a vertical... The system consists of intersecting horizontal and vertical axes. The horizontal axes are rotatably mounted on hinged seats at both ends, with their right ends connected to driven wheel assemblies, allowing them to rotate under the drive of the driven wheel assemblies. The vertical axes are rotatably mounted on connecting seats at both ends, with elastic elements between the connecting seats and the hinged seats on both sides, and a connecting screw fixed at the bottom. The foot end, fixedly connected to the connecting seat via the connecting screw, transmits the lateral load from contacting the uneven ground to the connecting seat, causing the connecting seat to perform passive lateral adjustment around the vertical axis, adaptively conforming to the walking surface, and using the elastic elements for cushioning, shock absorption, and flexible limiting. After the motor reverses and drives the foot end to lift off the working surface to remove the load, the elastic elements drive the connecting seat and the foot end to automatically return to the initial position, completing the leg lifting action.

[0007] Furthermore, the connecting mechanism also includes a connecting screw, a fourth bearing, and a fifth bearing; wherein, the horizontal shaft has a first stepped portion at both ends; the first stepped portion is interference-fitted with the inner ring of the fourth bearing, and the outer ring of the fourth bearing is interference-fitted with the third rotating hole of the hinge seat; the vertical shaft has a second stepped portion at both ends, the second stepped portion is interference-fitted with the inner ring of the fifth bearing, and the outer ring of the fifth bearing is interference-fitted with the fourth rotating hole of the connecting seat.

[0008] Furthermore, the connecting seat has a U-shaped structure with a fourth rotating hole symmetrically provided at its upper end and a second positioning protrusion provided at its bottom. The second positioning protrusion is embedded in the positioning groove at the foot end. The connecting screw passes through the second positioning protrusion and is threadedly locked with the fixing screw hole at the foot end to realize the fixed connection between the connecting seat and the foot end.

[0009] Furthermore, the elastic element is symmetrically sleeved at both ends of the cross shaft, located between the inner side of the hinge seat upright arm and the outer side of the connecting seat side plate, forming a bidirectional clamping flexible constraint on the lateral swing motion of the connecting seat; the elastic element is any one of a rubber spring, a corrugated spring, or a compression spring.

[0010] Furthermore, the motor is integrally embedded in the mounting cavity of the motor mounting base, which includes a stator flange and a rotor flange. The stator flange end face is provided with multiple sets of second screw holes circumferentially for fixed connection with the motor pressure plate. The motor pressure plate is an annular flange structure, with multiple sets of second countersunk holes evenly distributed circumferentially on its outer ring and multiple sets of third countersunk holes evenly distributed circumferentially on its inner ring. The motor pressure plate and the motor mounting base are fixedly connected by bolts passing through the second countersunk holes and threaded into the first screw holes. The motor pressure plate and the stator flange are fixedly connected by bolts passing through the third countersunk holes and threaded into the second screw holes. The rotor flange end face is provided with multiple sets of third screw holes evenly distributed circumferentially, and at least one set of first positioning protrusions. The first positioning protrusions are embedded in blind holes provided on the drive circular plate. A first polygonal hole is opened at the center of the drive circular plate. Multiple sets of first countersunk holes are provided on the outer periphery of the first polygonal hole, corresponding one-to-one with the third screw holes of the motor rotor flange. The drive circular plate and the rotor flange are completely integrated by bolts passing through the first countersunk holes and threaded into the third screw holes.

[0011] Furthermore, the transmission mechanism also includes a gearbox cover and a transmission wheel assembly; the upper end of the gearbox cover is rigidly locked to the right end face of the motor mounting base, and the lower end is rigidly locked to the right end face of the hinge base. The end face is provided with a first rotating hole, a fixed hole, and a second rotating hole from top to bottom, which provide mounting support positions for the driving wheel assembly, the transmission wheel assembly, and the driven wheel assembly, respectively.

[0012] Furthermore, the drive wheel assembly includes a drive gear, a drive shaft, a first prism, and a first bearing; the drive gear is interference-fitted and fixed on the drive shaft; the right end of the drive shaft is interference-fitted with the inner ring of the first bearing, and the outer ring of the first bearing is interference-fitted with the first rotating hole of the gearbox cover; the first prism is located at the left end of the drive shaft and inserted into the first polygonal hole.

[0013] Furthermore, the transmission wheel assembly includes a transmission gear, a fixed bushing, a limiting screw, and a second bearing; the upper end of the transmission gear meshes with the driving gear and is interference-fitted and fixed to the second bearing; the inner ring of the second bearing is fitted and fixed to the fixed bushing, and the limiting screw passes through the fixing hole and is threadedly connected to the fixed bushing to limit the two ends of the second bearing.

[0014] Furthermore, the driven wheel assembly includes a driven gear, a driven shaft, a second prism, and a third bearing; the driven gear meshes with the lower end of the transmission gear and is interference-fitted and fixed to the driven shaft; the right end of the driven shaft is interference-fitted with the inner ring of the third bearing, and the outer ring of the third bearing is interference-fitted with the second rotating hole of the gearbox cover; the second prism is located at the left end of the driven shaft, and the two are formed together, matching the size of the second polygonal hole at the right end of the cross shaft. By embedding the second prism in the second polygonal hole, the torque is transmitted to the cross shaft to complete the precise active adjustment of the pitch angle.

[0015] According to another aspect of the present invention, a walking method using an active ankle joint magnetic foot device suitable for footed robots is also provided, comprising the following steps: S1: Complete the rigid connection between the foot connector and the robot's lower leg foot; S2: Based on the terrain of the target landing point, control the motor to rotate, output power and transmit it to the horizontal axis of the cross shaft through the transmission mechanism, so as to drive the foot to complete the precise adjustment of the pitch angle; S3: The foot falls with the robot's gait planning and makes contact with the work surface; S4: When the foot contacts an uneven ground, it drives the connecting seat to complete passive side swing micro-adjustment around the longitudinal axis of the cross axis, adaptively conforming to the uneven structure of the ground, and simultaneously completing buffering, shock absorption and flexible limiting through the elastic element; S5: For ferromagnetic working surfaces, control the foot end to generate magnetic adsorption force, improve adhesion stability, and reduce robot joint compensation torque and overall energy consumption; S6: The motor locks the foot posture, providing stable rigid support for the robot's walking and completing the gait support phase load-bearing operation; S7: The motor reverses and lifts the foot off the work surface. The elastic element drives the connecting seat and the foot to automatically return to the initial position, completing the leg lifting action. S8: Repeat steps S2-S7 to complete the robot's continuous all-terrain walking operation.

[0016] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects: 1. The ankle joint magnetic foot device of the present invention, through the orthogonal hinge structure of the cross axis and the symmetrical arrangement of elastic elements, sets the pitch degree of freedom of the foot to active control and the lateral swing degree of freedom to passive adaptation. Only a single motor is needed to complete the core posture control of the foot, abandoning the redundant architecture of the existing multi-motor collaboration, reducing the dimension from dual-input multi-variable control to single-degree-of-freedom precise control, and completely avoiding the interference and oscillation risks of multi-motor collaboration; at the same time, the lateral swing limit, buffering and reset functions are completely realized by the passive mechanical structure, without the need for additional drive, sensing equipment and control algorithms, and are completely decoupled from the active pitch control, resulting in a lower system failure rate and stronger operational stability.

[0017] 2. The ankle joint magnetic foot device of the present invention, through the vertically compact arrangement of three gears in the transmission mechanism, moves the pitch and rotation center of the foot to the maximum extent to be close to its magnetic adsorption working surface, significantly shortening the transmission arm. This fundamentally solves the problems of attachment offset, hanging edge, and force bias caused by excessively long lever arms in the prior art. Combined with the passive adaptive function of foot side swing, it can adapt to complex terrains such as inclined walls, uneven ground, and steps, ensuring maximum surface contact and adhesion between the foot and the working surface, while maximizing the magnetic adsorption efficiency, significantly improving the adhesion stability of ferromagnetic surface operations, and reducing the energy consumption of robot joints.

[0018] 3. The ankle joint magnetic foot device of the present invention is manufactured by integral molding of the foot connecting seat, motor mounting seat and hinge seat to form a closed-loop high-strength load-bearing frame. It eliminates redundant parts such as independent brackets and connecting seats in the split design, which greatly reduces the number of parts and the cumulative assembly error. At the same time, the motor is embedded in the mounting cavity and combined with the minimalist design of single motor pressure plate locking and drive circular plate transfer, which maximizes the reduction of space occupation. Under the premise of fully realizing the two-degree-of-freedom ankle joint function, it significantly reduces the mass and rotational inertia of the robot leg end, thereby meeting the core design requirements of lightweight and compact leg end of footed robots.

[0019] 4. The ankle joint magnetic foot device of the present invention completely eliminates the backlash caused by traditional couplings, key connections, and other structures, through the direct insertion docking design of the first polygonal hole of the driving circular plate with the first prism of the active wheel assembly and the second prism of the driven wheel assembly with the second polygonal hole of the cross shaft. The transmission is gapless and lag-free throughout the entire process, and the control accuracy of the foot pitch posture is greatly improved. At the same time, the transmission chain is short and there are no redundant intermediate transmission links, which greatly reduces the equivalent inertia of the transmission system. It can quickly respond to the drive signal of the control system, perfectly adapt to the high-speed and high-dynamic motion requirements of legged robots, and can flexibly cope with sudden terrain changes. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of an active ankle joint magnetic foot device suitable for legged robots according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the motor drive mechanism in an embodiment of the present invention; Figure 3 This is an exploded view of the motor drive mechanism in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of the driving circular plate in an embodiment of the present invention; Figure 5 This is a schematic diagram of the transmission mechanism in an embodiment of the present invention; Figure 6 This is an exploded view of the transmission mechanism in an embodiment of the present invention; Figure 7This is a schematic diagram of the limiting connection mechanism in an embodiment of the present invention; Figure 8 This is a three-dimensional structural diagram of the limiting connection mechanism in an embodiment of the present invention; Figure 9 This is an exploded view of the limiting connection mechanism in an embodiment of the present invention; Figure 10 This is a schematic diagram of the cross shaft structure in an embodiment of the present invention; Figure 11 This is a schematic diagram of the connecting seat in an embodiment of the present invention; Figure 12 This is a schematic diagram of the foot end in an embodiment of the present invention.

[0021] In all the accompanying drawings, the same reference numerals denote the same technical features, specifically: 1-Leg connector; 2-Motor drive mechanism, including: 21-Motor mounting base, 211-Mounting cavity, 222-First screw hole, 22-Drive circular plate, 221-First polygonal hole, 222-First countersunk hole, 223-Blind hole, 23-Motor pressure plate, 231-Second countersunk hole, 232-Third countersunk hole, 24-Motor, 241-Stator flange, 242-Rotor flange, 243-Second screw hole, 244-Third screw hole, 245-First positioning protrusion; 3-Transmission mechanism, including: 31-Gearbox cover, 311-Fourth countersunk hole, 312-First rotating hole, 313-Fixed hole, 314-Second rotating hole, 32-Driving wheel assembly, 321-Driving gear, 322-Driving shaft, 323-First prism, 324-First bearing, 33-Transmission wheel assembly, 331-Transmission gear, 332-Fixed bushing, 333-Limiting screw, 334-Second bearing, 34-Driven wheel assembly, 341-Driven gear, 342-Driven shaft, 343-Second prism, 344-Third bearing; 4-Hinged seat, including: 401-Third rotating hole, 402-Fourth screw hole; 5-Connecting mechanism, including: 51-Cross shaft, 511-Horizontal shaft, 512-Vertical shaft, 513-First step portion, 514-Second step portion, 515-Second polygonal hole, 52-Connecting seat, 521-Seat plate, 522-Side plate, 523-Fourth rotating hole, 524-Positioning protrusion, 525-Positioning square hole, 526-Fifth countersunk hole, 527-Sixth countersunk hole, 528-Second positioning protrusion, 529-Circumferential step portion, 53-Elastic element, 54-Bearing pressure plate, 55-Connecting screw, 56-Fourth bearing, 57-Fifth bearing; 6-Foot end, including: 601-Positioning groove, 602-Fixing screw hole. Detailed Implementation

[0022] 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.

[0023] like Figure 1-12 As shown, this invention provides an active ankle joint magnetic foot device suitable for legged robots, including a foot limb connecting seat 1, a motor drive mechanism 2, a transmission mechanism 3, a hinge seat 4, a connecting mechanism 5, and a foot end 6. The foot limb connecting seat 1 is fixedly disposed on the lower left side of the motor drive mechanism 2 for connecting the robot's foot limb. The motor drive mechanism 2 includes a motor mounting seat 21 and a motor 24. The motor 24 is fixedly disposed in the motor mounting seat 21 and outputs power through a rotor flange 242. The transmission mechanism 3 is fixedly disposed on the right side of the motor drive mechanism 4 and includes an active wheel assembly 32 and a driven wheel assembly 34. The active wheel assembly 32 is fixedly connected to the rotor flange 242 and transmits power to the driven wheel assembly 34 at its bottom. Wheel assembly 34; the hinge seat 4 is fixedly mounted on the bottom of the motor mounting base 21, and has an inverted U-shaped structure for hinge connection mechanism 5; the connection mechanism 5 includes a cross shaft 51, a connecting seat 52, an elastic element 53, and a connecting screw 55. The cross shaft 51 includes a horizontal shaft 511 and a vertical shaft 512 that are perpendicularly intersecting. The two ends of the horizontal shaft 511 are rotatably mounted on the hinge seat 4, and its right end is connected to the driven wheel assembly 34 and rotates under the drive of the driven wheel assembly 34. The two ends of the vertical shaft 512 are rotatably mounted on the connecting seat 52. The connecting seat 52 is provided with elastic elements 53 between its two sides and the hinge seat 4, and the bottom is fixedly provided with a connecting screw 55; the foot end 6 is fixedly connected to the connecting seat 52 through the connecting screw 55. The magnetic foot device of the present invention precisely controls the position of the rotation center through the transmission mechanism 3, shortens the transmission arm, avoids attachment deviation caused by excessive arm length, and allows the foot end 6 to smoothly conform to the wall surface and complex terrain. The power transmission has no obvious loss and the dynamic response is faster. At the same time, the cross shaft 51 and the elastic element 53 realize active pitch control and passive lateral sway self-adaptation. No additional drive, sensing equipment and control algorithm are required, the device has a lower failure rate and stronger operational stability.

[0024] like Figure 1As shown in the embodiment of the invention, the foot connector 1 is a dedicated docking base adapted to the mounting contour of the robot's foot end. The main body adopts a U-shaped groove insertion docking structure. The width of the groove precisely matches the outer diameter of the robot's lower leg end insertion section. Multiple sets of through-hole connecting bolts are coaxially formed on both sides of the groove wall in the horizontal direction. During assembly, the robot's foot end is inserted into the U-shaped groove for radial positioning. High-strength bolts are then threaded through the groove wall and locked to the mounting holes of the robot's foot end in the horizontal direction, achieving a rigid connection between the foot connector 1 and the robot's foot. This connection method converts the vertical load into the axial tensile force of the bolts, completely eliminating the bolt shear load caused by traditional vertical installation methods. This significantly improves the impact resistance and load-bearing stability of the connection structure, preventing loosening and structural failure during high-speed robot movement and impact landing.

[0025] like Figure 2-3 As shown, in this embodiment of the invention, the motor drive mechanism 2 transmits the rotational torque of the motor to the transmission mechanism 3 without loss, thereby driving the connecting mechanism to drive the foot end 6 to complete the precise active adjustment of the pitch angle. It includes a motor mounting base 21, a drive circular plate 22, a motor pressure plate 23, and a motor 24.

[0026] The motor mounting base 21, the foot connecting base 1, and the hinge base 4 are integrally formed, thereby improving the structural rigidity, assembly coaxiality, and compactness of the device. An installation cavity 211 that is precisely matched to the outer diameter of the motor 24 is opened along the direction of the motor output axis. The opening of the installation cavity 211 faces the transmission mechanism 3. Furthermore, multiple sets of first screw holes 222 are evenly distributed on the outer peripheral end face of the opening side of the installation cavity 211 for bolt locking and fixing with the motor pressure plate 23.

[0027] The motor 24 is integrally embedded in the mounting cavity 211 of the motor mounting base 21, without an additional reduction mechanism, directly outputting rotational torque, significantly reducing the equivalent inertia of the transmission chain and improving dynamic response speed. The motor 24 includes a stator flange 241 and a rotor flange 242, which are used to fix the stator and output power to the rotor, respectively. The end face of the stator flange 241 is provided with multiple sets of second screw holes 243 in the circumferential direction for fixed connection with the motor pressure plate 23. The motor pressure plate 23 firmly locks the stator in the mounting cavity 211, preventing the stator from rotating radially when the motor outputs torque and ensuring the stability of torque output. The rotor flange 242 has multiple sets of third screw holes 244 evenly distributed circumferentially on its end face, and at least one set of first positioning protrusions 245. The first positioning protrusions 245 are used to achieve rapid coaxial positioning with the drive circular plate 22 to prevent assembly eccentricity. The third screw holes 244 are used to achieve bolt locking and fixation with the drive circular plate 22, so as to transmit the rotational torque of the rotor to the drive circular plate 22 without loss, and finally to the transmission mechanism 3.

[0028] The motor pressure plate 23 is an annular flange structure, with multiple sets of second countersunk holes 231 evenly distributed on its outer circumference and multiple sets of third countersunk holes 232 evenly distributed on its inner circumference. By using bolts to pass through the second countersunk holes 231 and threadedly lock them into the first screw hole 222, the motor pressure plate 23 is fixedly connected to the motor mounting base 21. By using bolts to pass through the third countersunk holes 232 and threadedly lock them into the second screw hole 243, the motor pressure plate 23 is fixedly connected to the stator flange 241, thereby preventing the motor 24 from rotating radially when outputting torque in the mounting cavity 211 and ensuring the stability of torque output.

[0029] The drive circular plate 22 serves as a torque transmission bridge between the motor 24 and the transmission mechanism 3, enabling coaxial connection between the motor output power and the transmission mechanism 3, ensuring the synchronization and accuracy of torque transmission. A first polygonal hole 221 is provided at the center of the drive circular plate 22, preferably using non-circular polygonal hole structures such as hexagonal or octagonal holes, which perfectly matches the first prism 323 of the drive wheel assembly 32 in the transmission mechanism 3. The first prism 323 is inserted into the first polygonal hole 221, achieving complete circumferential limiting and eliminating slippage and backlash issues during torque transmission, ensuring the accuracy of foot pitch control. Multiple sets of first countersunk holes 222 are provided on the outer periphery of the first polygonal hole 221, corresponding one-to-one with the third threaded holes 244 of the motor rotor flange 242. By using bolts to pass through the first countersunk holes 222 and the third threaded holes 244 and lock them together, the drive circular plate 22 and the rotor flange 242 are completely integrated, achieving rigid and lossless transmission of rotational torque. Furthermore, a blind hole 223 is provided on the end face of the drive plate 22 facing the motor 24. The blind hole 223 corresponds to the first positioning protrusion 245. By embedding the first positioning protrusion 245 in the blind hole 223, the drive plate 22 and the motor rotor flange can be quickly coaxially positioned, ensuring assembly coaxiality and avoiding transmission vibration and part wear caused by eccentricity.

[0030] In this embodiment of the invention, the motor 24 is embedded in the integrally formed motor mounting base 21, and locked with the motor pressure plate 23 and driven by the circular plate 22 to output power. This eliminates redundant components such as independent motor brackets and couplings in the prior art, greatly reducing the size and weight of the mechanism and significantly reducing the end inertia of the robot's legs, thereby meeting the core requirements of lightweight and compact legged robots.

[0031] like Figure 5-6As shown, in this embodiment of the invention, the transmission mechanism 3 accurately and without lag transmits the rotational torque of the motor to the connecting mechanism 5, realizing closed-loop active control of the pitch posture of the foot 6. The transmission mechanism 3 is fixedly mounted on the right end face of the motor drive mechanism 2 and the hinge seat 4. Its upper end is rigidly connected to the motor mounting base 21, and its lower end is rigidly connected to the hinge seat 4. Together with the motor mounting base 21 and the hinge seat 4, it forms a closed gear transmission protective cavity, isolating the transmission components from external dust, debris, and impact loads. It includes a gearbox cover 31, a drive wheel assembly 32, a transmission wheel assembly 33, and a driven wheel assembly 34.

[0032] The gearbox cover 31 has multiple sets of fourth countersunk holes 311 evenly distributed around its right end face. By using bolts to pass through the fourth countersunk holes 311 for threaded connection, the upper end of the gearbox cover 31 is rigidly locked to the right end face of the motor mounting base 21, and the lower end is rigidly locked to the right end face of the hinge base 4. Furthermore, the right end face of the gearbox cover 31 has a first rotating hole 312, a fixed hole 313, and a second rotating hole 314 from top to bottom, which provide mounting support positions for the drive wheel assembly 32, the transmission wheel assembly 33, and the driven wheel assembly 34, respectively.

[0033] The drive wheel assembly 32 is connected to the drive disc 22 of the motor drive mechanism 2 to achieve lossless and backlash-free reception of the motor output torque. It includes a drive gear 321, a drive shaft 322, a first prism 323 and a first bearing 324. The drive gear 321 is interference-fitted and fixed to the middle section of the drive shaft 322, maintaining complete synchronous rotation with the drive shaft 322 without relative rotation or slippage. The right end of the drive shaft 322 is interference-fitted with the inner ring of the first bearing 324, and the outer ring of the first bearing 324 is interference-fitted with the first rotating hole 312 of the gearbox cover 31, achieving low-friction, high-coaxiality rotational support for the drive shaft 322 and eliminating radial movement. The first prism 323 is located at the left end of the drive shaft 322, and the two are integrally formed. The first prism 323 adopts a non-circular polygonal prism structure such as a regular hexagon or regular octagon, which is perfectly matched with the size of the first polygonal hole 221 at the center of the drive circular plate 22. During assembly, the first prism 323 is directly inserted into the first polygonal hole 221, achieving complete circumferential positioning. This completely eliminates the traditional coupling structure, eliminates the transmission backlash, assembly error, and part redundancy caused by the coupling, and achieves lossless and lagless torque transmission, greatly improving the accuracy of foot posture control.

[0034] The transmission wheel assembly 33 is used to achieve speed reduction and torque increase. It includes a transmission gear 331, a fixed bushing 332, a limiting screw 333, and a second bearing 334. The upper and lower ends of the transmission gear 331 are precisely meshed with the driving gear 321 and the driven gear 341, respectively, and are interference-fitted and fixed to the second bearing 334. The gear ratio achieves a preset speed reduction ratio, providing high torque and low speed power output for foot pitching motion, which is suitable for the load requirements of the ankle joint of the footed robot. The inner ring of the second bearing 334 is fitted and fixed to the fixed bushing 332. The limiting screw 333 passes through the fixing hole 313 and is threadedly connected to the fixed bushing 332, limiting the two ends of the second bearing 334 to prevent axial movement of the bearing and gear, and avoiding gear misalignment, tooth breakage, and other failures.

[0035] The driven wheel assembly 34 is the power output port of the transmission mechanism 3, which directly outputs the torque after the three-stage gear transmission to the cross shaft 51 of the connecting mechanism 5; the driven wheel assembly 34 includes a driven gear 341, a driven shaft 342, a second prism 343 and a third bearing 344. The driven gear 341 meshes with the transmission gear 331 and is interference-fitted and fixed on the driven shaft 342, maintaining complete synchronous rotation with the driven shaft 342. The right end of the driven shaft 342 is interference-fitted with the inner ring of the third bearing 344, and the outer ring of the third bearing 344 is interference-fitted with the second rotating hole 314 of the gearbox cover 31, achieving high coaxiality and low friction rotational support for the driven shaft 342 and eliminating radial and axial movement. The second prism 343 is located at the left end of the driven shaft 342, and the two are formed together, perfectly matching the size of the second polygonal hole 515 at the right end of the cross shaft 51 horizontal axis 511. By embedding the second prism 343 into the second polygonal hole 515, the torque is transmitted to the cross shaft 51, completing the precise active adjustment of the foot end 6 pitch angle. The entire transmission chain has no additional transfer links, and the cumulative error approaches zero.

[0036] In this embodiment of the invention, the three-stage gear transmission spatial arrangement of the active wheel assembly 32, the transmission wheel assembly 33, and the driven wheel assembly 34 moves the pitch and rotation center of the foot closer to and closer to the magnetic adsorption working surface of the foot 6, shortening the transmission arm from the structural root and achieving full contact surface contact between the foot 6 and the working surface. This transmission mechanism 3 has a short transmission chain, fewer parts, and high integration, with no redundant connecting parts, which greatly reduces the equivalent inertia of the transmission system and can quickly respond to the drive signals of the control system, adapting to the high-speed and high-dynamic motion requirements of legged robots.

[0037] In another embodiment of the present invention, the driving wheel assembly 32 and the driven wheel assembly 34 can transmit power through flexible transmission methods such as belt drive and chain drive, and can also be rigidly transmitted between them through two-stage gears; the transmission wheel assembly 33 can output power by adjusting different torques through multi-stage gears.

[0038] The hinge seat 4 is used for the hinge connection mechanism 5. It is fixedly installed at the bottom of the motor mounting seat 21 and has an inverted U-shaped structure. It includes a crossbeam and vertical arms symmetrically arranged on both sides of the crossbeam. The lower ends of the two sets of vertical arms are respectively provided with third rotating holes 401 to provide coaxial rotation support for the cross shaft 51. Furthermore, multiple sets of fourth screw holes 402 are provided axially on the outer side of the third rotating hole 401, which are used to fix the bearing pressure plate 54 of the connection mechanism 5 by cooperating with bolts.

[0039] like Figure 7-11 As shown in the embodiment of the present invention, the connecting mechanism 5 is used to realize the active and precise control of the foot pitch degree of freedom and the passive and flexible self-adaptation of the lateral swing degree of freedom; the connecting mechanism 5 includes a cross shaft 51, a connecting seat 52, an elastic element 53, a bearing pressure plate 54, a connecting screw 55, a fourth bearing 56 and a fifth bearing 57.

[0040] The cross shaft 51 includes a horizontal shaft 511 and a vertical shaft 512 that are perpendicularly intersecting and integrally formed. The two shaft axes are spatially orthogonal and coplanar. The horizontal shaft 511 is a pitch active rotation shaft with first stepped portions 513 at both ends. The first stepped portion 513 is interference-fitted with the inner ring of the fourth bearing 56, and the outer ring of the fourth bearing 56 is interference-fitted with the third rotation hole 401 of the hinge seat 4, so as to realize low friction and high coaxiality rotation of the horizontal shaft 511 on the hinge seat 4. Furthermore, a second polygonal hole 515 is opened at the center of the right end of the horizontal shaft 511, which is perfectly matched with the size of the second prism 343 of the driven wheel assembly 34. By embedding the second prism 343, the torque output by the transmission mechanism 3 is received, and the cross shaft 51 is directly driven to complete the pitch rotation. The longitudinal axis 512 is a passive lateral swing axis with second step portions 514 at both ends. The second step portion 514 is interference-fitted with the inner ring of the fifth bearing 57, and the outer ring of the fifth bearing 57 is interference-fitted with the fourth rotation hole 523 of the connecting seat 52. This enables the connecting seat 52 to perform low-friction passive lateral swing around the longitudinal axis 512, completely decoupling the active pitch motion and the passive lateral swing motion, so that they do not interfere with each other.

[0041] In this embodiment of the invention, a two-degree-of-freedom orthogonal hinge is achieved through the cross shaft 51, which eliminates the redundant structure of multiple links and multiple hinge pairs in the prior art, greatly reduces the number of parts, shortens the transmission chain, and ensures complete decoupling of active and passive motion. From the mechanical structure level, it avoids the interference risk of multi-degree-of-freedom motion and greatly reduces the complexity of the control system.

[0042] The connecting seat 52 is used to connect the cross shaft 51 and the foot end 6, and at the same time provides rotational support for the passive lateral movement and provides a limiting reference for the elastic element 53. It has a U-shaped structure, including a seat plate 521, a side plate 522, a fourth rotating hole 523, a positioning protrusion 524, a positioning square hole 525, a fifth countersunk hole 526, a sixth countersunk hole 527, a second positioning protrusion 528, and a circumferential step portion 529. The base plate 521 is an L-shaped integrated structure, including a horizontal base plate and a vertical plate. The front end of the base plate has a positioning protrusion 524, which can be precisely embedded into the positioning square hole 525 at the lower end of the side plate 522, achieving rapid coaxial positioning of the base plate 521 and the side plate 522 without the need for additional tooling to ensure assembly accuracy. By using bolts passing through the fifth countersunk hole 526 on the side plate 522 and threadedly locking it to the base plate, a rigid connection between the base plate 521 and the side plate 522 is achieved, forming a U-shaped frame and significantly simplifying the assembly process. The fourth rotating hole 523 is coaxially and symmetrically opened on the vertical plate and the side plate 522, and the hole has a circumferential step 529, which connects with the longitudinal... The second step portion 514 at both ends of the shaft 512 cooperates to form a bidirectional axial limit for the fifth bearing 57, preventing axial movement between the bearing and the connecting seat and ensuring the stability of the lateral swing motion; the sixth countersunk hole 527 is located at the center of the base plate, and a second positioning protrusion 528 is provided at its bottom. The second positioning protrusion 528 is embedded in the positioning groove 601 of the foot end 6 to realize the quick coaxial positioning of the connecting seat 52 and the foot end 6 and ensure the coaxiality of the installation; the connecting screw 55 passes through the sixth countersunk hole 527 and the second positioning protrusion 528 in sequence, and is threadedly locked with the fixing screw hole 602 of the foot end 6 to realize the fixed connection between the connecting seat 52 and the foot end 6.

[0043] The elastic element 53 is symmetrically sleeved at both ends of the cross shaft 511, located between the inner side of the vertical arm of the hinge seat 4 and the outer side of the side plate of the connecting seat 52, forming a bidirectional clamping flexible constraint on the lateral swing motion of the connecting seat 52. The elastic element 53 is any one of rubber spring, corrugated spring, and compression spring, used to limit the maximum lateral swing angle between the connecting seat 52 and the foot end 6, avoiding motion interference and structural damage caused by excessive lateral swing. When the foot end contacts the uneven ground and encounters lateral impact, it absorbs the impact load through elastic deformation, reducing the impact damage to the robot's leg joints and transmission mechanism. When the foot end is lifted and the lateral load is unloaded, the elastic restoring force drives the connecting seat 52 and the foot end 6 to automatically reset to the centered initial position, ensuring the consistency and accuracy of the robot's gait for each step. By incorporating the elastic element 53, the limiting, buffering, and resetting functions of the foot's side swing are entirely achieved by the passive mechanical structure, eliminating the need for additional drive motors, sensors, and control algorithms. This completely decouples the system from the active pitch control, significantly reducing system complexity and failure rate, while also not increasing the end-effector inertia of the legs, perfectly meeting the lightweight and highly dynamic motion requirements of legged robots.

[0044] The bearing pressure plate 54 is an annular thin plate structure, which is fixed to the outer end face of the third rotating hole 401 of the hinge seat 4 by bolts. It works in conjunction with the first step 513 of the horizontal shaft 511 to form a bidirectional axial limit on the fourth bearing 56, preventing the bearing from moving axially and ensuring the smoothness of pitch rotation.

[0045] In this embodiment of the invention, when the connecting mechanism 5 performs active pitch control, power is transmitted to the horizontal axis 511 of the cross shaft 51 via the transmission mechanism 3, driving the cross shaft 51 to rotate around the horizontal axis, thereby causing the connecting seat 52 and the foot end 6 to synchronously complete the precise active adjustment of the pitch angle; there are no intermediate connecting links throughout the process, the transmission is backlash-free and lag-free, and the pitch angle of the foot end can be precisely controlled to ensure maximum contact between the foot end and the working surface. Combined with the short lever arm design of the transmission mechanism 3, it achieves smooth attachment between the foot end and the wall surface, avoiding edge lifting and suspension; when performing passive adaptive lateral movement, the foot end... When the end is subjected to a lateral load, the connecting seat 52 is driven to passively sway around the longitudinal axis 512 of the cross shaft 51. The elastic element 53 on the corresponding side is compressed and generates elastic deformation, while the elastic element 53 on the opposite side releases the preload simultaneously. This allows the foot to sway slightly to adapt to the ground, ensuring the effective contact area between the foot and the ground and avoiding force bias. At the same time, the elastic force of the elastic element 53 continuously provides flexible support for the foot and absorbs the lateral impact load. When the foot is lifted and the lateral load is unloaded, the elastic element 53 drives the connecting seat 52 and the foot to automatically return to center through the elastic restoring force, ensuring the consistency of the robot's gait.

[0046] like Figure 12 As shown, in this embodiment of the invention, the foot end 6 is used for working surface contact, and includes a positioning groove 601 at the top center of the foot end 6 and a fixing screw hole 602 at the bottom center of the positioning groove 601. The second positioning protrusion 528 at the bottom of the connecting seat 52 is tightly embedded in the positioning groove 601 to ensure the coaxiality of the two installations and avoid force misalignment and uneven attachment caused by assembly eccentricity. After the connecting screw 55 passes through the sixth countersunk hole 527 of the connecting seat 52 and the central through hole of the second positioning protrusion 528 in sequence, it is threaded and locked with the fixing screw hole 602 to realize the integrated rigid connection between the foot end 6 and the connecting seat 52, and transmit the pitch rotation and lateral swing of the connecting mechanism 5 to the foot end 6 without loss. Furthermore, by loosening the connecting screw 55, the circumferential installation angle of the foot end 6 can be rotated and adjusted to adapt to the magnetic adsorption direction requirements of different working conditions. After adjustment, it can be re-locked to complete the fixation.

[0047] Furthermore, the bottom of the foot end 6 is provided with a magnetic adsorption module. By being electrically connected to the corresponding magnetic adsorption drive unit, a controllable magnetic adsorption force output can be realized, so that the foot end 6 generates a magnetic adsorption force when working, thereby adsorbing onto the ferromagnetic working surface and ensuring the robot's attachment stability.

[0048] When the active ankle joint magnetic foot device of the present invention is in operation, the motor 24 of the motor drive mechanism 2 outputs rotational power, which is transmitted without backlash to the active wheel assembly 32 of the transmission mechanism 3 via the drive circular plate 22. After being reduced and increased in torque by the transmission wheel assembly 33, it is transmitted to the driven wheel assembly 34. The driven wheel assembly 34 directly drives the horizontal shaft 511 of the cross shaft 51 to rotate, thereby driving the foot end 6 to complete the precise active control of the pitch angle through the connecting seat 52. At the same time, the vertical arrangement design of the three-stage gears of the transmission mechanism 3 brings the pitch rotation center of the foot end 6 close to its magnetic adsorption working surface, greatly shortening the transmission arm and ensuring the smooth contact between the foot end 6 and the working surface. When the foot end 6 lands and contacts the working surface with the robot's gait... When working on a surface, the robot can achieve passive adaptive fine-tuning of the lateral swing direction through the longitudinal axis 512 of the cross axis 51. Simultaneously, the elastic element 53, symmetrically arranged between the hinge seat 4 and the connecting seat 52, completes the buffering, shock absorption, and flexible limiting. When working on a ferromagnetic surface, the foot end 6 generates magnetic adsorption force to improve adhesion stability and reduce overall energy consumption. When the robot is in the gait support phase, the motor 24 locks and fixes the posture of the foot end 6, providing stable rigid support for the robot's walking. During the leg lifting phase, the motor 24 drives the foot end 6 in the reverse direction to lift it off the working surface. The elastic element 53 synchronously drives the connecting seat 52 and the foot end 6 to automatically return to the initial center position. This cycle completes the robot's continuous all-terrain walking and special wall adsorption operations.

[0049] The ankle joint magnetic foot device of the present invention, through the orthogonal hinge structure of the cross shaft 51 and the symmetrically arranged elastic element 53, sets the pitch degree of freedom of the foot to active control and the lateral swing degree of freedom to passive adaptation. Only a single motor 24 is needed to complete the core posture control of the foot. It abandons the redundant architecture of multi-motor collaboration in the prior art, reduces the dimension of dual-input multi-variable control to single-degree-of-freedom precise control, and completely avoids the interference and oscillation risks of multi-motor collaboration. At the same time, the lateral swing limit, buffer and reset functions are completely realized by the passive mechanical structure, without the need for additional drive, sensing equipment and control algorithm, and are completely decoupled from active pitch control, resulting in a lower system failure rate and stronger operational stability.

[0050] The ankle joint magnetic foot device of the present invention, through the vertically compact arrangement of the three-stage gears of the transmission mechanism 3, moves the pitch and rotation center of the foot end 6 to the maximum extent to be close to its magnetic adsorption working surface, which greatly shortens the transmission arm and solves the problems of attachment offset, hanging edge, and force bias caused by excessively long lever arm in the prior art from the structural root. With the passive adaptive function of the side swing of the foot end 6, it can adapt to complex terrains such as inclined walls, uneven ground, and steps, ensuring maximum surface contact and fit between the foot end and the working surface, while maximizing the magnetic adsorption efficiency, significantly improving the adhesion stability of ferromagnetic surface operation, and reducing the energy consumption of robot joints.

[0051] The ankle joint magnetic foot device of the present invention is manufactured by integral molding of the foot connecting seat 1, motor mounting seat 21, and hinge seat 4, forming a closed-loop high-strength load-bearing frame. It eliminates redundant parts such as independent brackets and connecting seats in the split design, greatly reducing the number of parts and the cumulative assembly error. At the same time, the motor 24 is embedded in the mounting cavity 211, and is locked with a single motor pressure plate 23 and driven by a circular plate 22. The minimalist design maximizes the reduction of space occupation. Under the premise of fully realizing the two-degree-of-freedom ankle joint function, it significantly reduces the mass and rotational inertia of the robot's leg end, thereby meeting the core design requirements of lightweight and compact leg end of footed robots.

[0052] The ankle joint magnetic foot device of the present invention completely eliminates the backlash structures of traditional couplings and keyed connections by using a direct insertion design between the first polygonal hole 221 of the driving circular plate 22 and the first prism 323 of the active wheel assembly 32, and the second prism 343 of the driven wheel assembly 34 and the second polygonal hole 515 of the cross shaft 51. The transmission is backlash-free and lag-free throughout the entire process, and the accuracy of foot pitch posture control is greatly improved. At the same time, the transmission chain is short and there are no redundant intermediate transmission links, which greatly reduces the equivalent inertia of the transmission system. It can quickly respond to the drive signal of the control system, perfectly adapt to the high-speed and high-dynamic motion requirements of legged robots, and flexibly cope with sudden terrain changes.

[0053] In this embodiment of the invention, a walking method using an active ankle joint magnetic foot device suitable for legged robots is also provided, comprising the following steps: S1: Complete the rigid connection between the foot connection seat 1 and the robot's lower leg foot; S2: Based on the terrain of the target landing point, control the motor 24 to rotate, output power and transmit it through the transmission mechanism 3 to the horizontal axis 511 of the cross axis 51, thereby driving the foot end 6 to complete the precise adjustment of the pitch angle; S3: Foot 6 descends according to the robot's gait plan and makes contact with the work surface; S4: When the foot end 6 contacts the uneven ground, it drives the connecting seat 52 to complete the passive side swing fine adjustment around the longitudinal axis 512 of the cross axis 51, adaptively conforming to the uneven structure of the ground, and simultaneously completing the buffering and shock absorption and flexible limiting through the elastic element 53. S5: For ferromagnetic working surfaces, control the foot end 6 to generate magnetic adsorption force, improve adhesion stability, and reduce robot joint compensation torque and overall energy consumption; S6: Motor 24 locks the foot end 6 posture, providing stable rigid support for robot walking and completing the gait support phase load-bearing operation; S7: Motor 24 reverses and drives foot 6 to lift off the working surface. Elastic element 53 drives connecting seat 52 and foot 6 to automatically return to the initial position, completing the leg lifting action. S8: Repeat steps S2-S7 to complete the robot's continuous all-terrain walking operation.

[0054] 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 active ankle joint magnetic foot device suitable for legged robots, characterized in that, include: Foot connector (1) connected to the robot's foot; The motor drive mechanism (2) is fixedly installed on the side of the foot connection seat (1), including a motor mounting seat (21) and a motor (24), wherein the motor (24) outputs power through a rotor flange (242); The transmission mechanism (3) located on the other side of the motor drive mechanism (2) includes a drive wheel assembly (32) and a driven wheel assembly (34), wherein the drive wheel assembly (32) transmits power to the driven wheel assembly (34) at its bottom. The hinge seat (4) located at the bottom of the motor mounting base (21) is formed together with the foot connecting seat (1) and the motor mounting base (21) and has a U-shaped structure; The connecting mechanism (5) hinged to the hinge seat (4) includes a cross shaft (51), a connecting seat (52), an elastic element (53), and a connecting screw (55). The cross shaft (51) includes a horizontal shaft (511) and a vertical shaft (512) that are perpendicularly intersecting. The two ends of the horizontal shaft (511) are rotatably mounted on the hinge seat (4), and its right end is connected to the driven wheel assembly (34) and rotates under the drive of the driven wheel assembly (34). The two ends of the vertical shaft (512) are rotatably mounted on the connecting seat (52). The connecting seat (52) is provided with elastic elements (53) on both sides between the connecting seat (52) and the hinge seat (4), and the bottom is fixedly provided with a connecting screw (55). The foot (6) is fixedly connected to the connecting seat (52) by the connecting screw (55). It transmits the lateral load from the uneven ground to the connecting seat (52), so that the connecting seat (52) can perform passive side swing adjustment around the longitudinal axis (512), adaptively conform to the walking work surface, and complete the buffering and shock absorption and flexible limit through the elastic element (53). After the motor (24) drives the foot (6) to lift off the work surface to unload the load, the elastic element (53) drives the connecting seat (52) and the foot (6) to automatically return to the initial position, completing the leg lifting action.

2. The active ankle joint magnetic foot device for legged robots according to claim 1, characterized in that, The connecting mechanism (5) further includes a connecting screw (55), a fourth bearing (56), and a fifth bearing (57); wherein, the horizontal shaft (511) has a first step portion (513) at both ends; the first step portion (513) is interference-fitted with the inner ring of the fourth bearing (56), and the outer ring of the fourth bearing (56) is interference-fitted with the third rotating hole (401) of the hinge seat (4); the vertical shaft (512) has a second step portion (514) at both ends, the second step portion (514) is interference-fitted with the inner ring of the fifth bearing (57), and the outer ring of the fifth bearing (57) is interference-fitted with the fourth rotating hole (523) of the connecting seat (52).

3. The active ankle joint magnetic foot device for legged robots according to claim 2, characterized in that, The connecting seat (52) has a U-shaped structure with a fourth rotating hole (523) symmetrically provided at its upper end and a second positioning protrusion (528) provided at its bottom. The second positioning protrusion (528) is embedded in the positioning groove (601) of the foot end (6). The connecting screw (55) passes through the second positioning protrusion (528) and is threadedly locked with the fixing screw hole (602) of the foot end (6) to realize the fixed connection between the connecting seat (52) and the foot end (6).

4. The active ankle joint magnetic foot device for legged robots according to claim 3, characterized in that, The elastic element (53) is symmetrically sleeved at both ends of the cross shaft (511) and located between the inner side of the vertical arm of the hinge seat (4) and the outer side of the side plate of the connecting seat (52), forming a bidirectional clamping flexible constraint on the lateral swing motion of the connecting seat (52); the elastic element (53) is any one of a rubber spring, a corrugated spring, or a compression spring.

5. An active ankle joint magnetic foot device suitable for legged robots according to any one of claims 1-4, characterized in that, The motor (24) is integrally embedded in the mounting cavity (211) of the motor mounting base (21), which includes a stator flange (241) and a rotor flange (242). The stator flange (241) has multiple sets of second screw holes (243) circumferentially arranged on its end face for fixed connection with the motor pressure plate (23); the motor pressure plate (23) is an annular flange structure, with multiple sets of second countersunk holes (231) evenly distributed on its outer circumference and multiple sets of third countersunk holes (232) evenly distributed on its inner circumference; the motor pressure plate (23) is fixedly connected to the motor mounting base (21) by using bolts to pass through the second countersunk holes (231) and threadedly lock them with the first screw holes (222); the motor pressure plate (23) is fixedly connected to the stator flange (241) by using bolts to pass through the third countersunk holes (232) and threadedly lock them with the second screw holes (243); The rotor flange (242) has multiple sets of third screw holes (244) evenly distributed around its end face, and at least one set of first positioning protrusions (245). The first positioning protrusions (245) are embedded in blind holes (223) on the drive circular plate (22). The drive circular plate (22) has a first polygonal hole (221) at its center. The outer periphery of the first polygonal hole (221) has multiple sets of first countersunk holes (222), which correspond one-to-one with the third screw holes (244) of the motor rotor flange (242). By using bolts to pass through the first countersunk holes (222) and the third screw holes (244) to lock them together, the drive circular plate (22) and the rotor flange (242) are completely connected as one unit.

6. An active ankle joint magnetic foot device suitable for legged robots according to claim 5, characterized in that, The transmission mechanism (3) also includes a gearbox cover (31) and a transmission wheel assembly (33). The upper end of the gearbox cover (31) is rigidly locked to the right end face of the motor mounting base (21), and the lower end is rigidly locked to the right end face of the hinge base (4). The end face is provided with a first rotating hole (312), a fixing hole (313), and a second rotating hole (314) from top to bottom, which provide mounting support positions for the drive wheel assembly (32), the transmission wheel assembly (33), and the driven wheel assembly (34), respectively.

7. An active ankle joint magnetic foot device suitable for legged robots according to claim 6, characterized in that, The drive gear assembly (32) includes a drive gear (321), a drive shaft (322), a first prism (323), and a first bearing (324); the drive gear (321) is interference-fitted and fixed on the drive shaft (322); the right end of the drive shaft (322) is interference-fitted with the inner ring of the first bearing (324), and the outer ring of the first bearing (324) is interference-fitted with the first rotating hole (312) of the gearbox cover (31); the first prism (323) is located at the left end of the drive shaft (322) and inserted into the first polygonal hole (221).

8. An active ankle joint magnetic foot device suitable for legged robots according to claim 7, characterized in that, The transmission wheel assembly (33) includes a transmission gear (331), a fixed bushing (332), a limiting screw (333), and a second bearing (334). The upper end of the transmission gear (331) meshes with the drive gear (321) and is interference-fitted and fixed to the second bearing (334). The inner ring of the second bearing (334) is fitted and fixed to the fixed bushing (332). The limiting screw (333) passes through the fixing hole (313) and is threadedly connected to the fixed bushing (332) to limit the two ends of the second bearing (334).

9. An active ankle joint magnetic foot device suitable for legged robots according to claim 8, characterized in that, The driven wheel assembly (34) includes a driven gear (341), a driven shaft (342), a second prism (343), and a third bearing (344). The driven gear (341) meshes with the lower end of the transmission gear (331) and is interference-fitted onto the driven shaft (342). The right end of the driven shaft (342) is interference-fitted with the inner ring of the third bearing (344), and the outer ring of the third bearing (344) is interference-fitted with the second rotating hole (314) of the gearbox cover (31). The second prism (343) is located at the left end of the driven shaft (342), and the two are formed together. The size of the second polygonal hole (515) at the right end of the cross shaft (511) is adapted to the size of the second polygonal hole (515). The torque is transmitted to the cross shaft (51) by the second prism (343) embedded in the second polygonal hole (515), thereby completing the precise active adjustment of the pitch angle of the foot (6).

10. A walking method using an active ankle joint magnetic foot device suitable for legged robots, characterized in that, Includes the following steps: S1: Complete the rigid connection between the foot connector (1) and the robot's lower leg foot; S2: Based on the terrain of the target landing point, control the motor (24) to rotate, output power and transmit it through the transmission mechanism (3) to the horizontal axis (511) of the cross shaft (51), driving the foot end (6) to complete the precise adjustment of the pitch angle; S3: The foot (6) falls with the robot's gait planning and makes contact with the working surface; S4: When the foot (6) contacts the uneven ground, it drives the connecting seat (52) to complete the passive side swing adjustment around the longitudinal axis (512) of the cross axis (51), adapting to the uneven ground structure, and simultaneously completing the buffering and shock absorption and flexible limiting through the elastic element (53). S5: For ferromagnetic working surfaces, control the foot end (6) to generate magnetic adsorption force, improve adhesion stability, and reduce robot joint compensation torque and overall energy consumption; S6: The motor (24) locks the foot end (6) posture, providing stable rigid support for the robot's walking and completing the gait support phase bearing operation; S7: The motor (24) reverses and drives the foot (6) to lift off the working surface. The elastic element (53) drives the connecting seat (52) and the foot (6) to automatically return to the initial position, completing the leg lifting action. S8: Repeat steps S2-S7 to complete the robot's continuous all-terrain walking operation.

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