A bidirectional passive obstacle-crossing scissor wheel-legged mechanism and a wheel-legged robot

Abstract

The application provides a bidirectional passive obstacle-crossing scissor wheel-leg mechanism and a wheel-leg robot, which has two moving states of wheel type and leg type. The mechanism comprises a driving unit, inner and outer wheel hubs, a plurality of wheel-leg units and elastic reset members. The driving unit is composed of a rotary driver, a rotary shaft and two locking unidirectional bearings with opposite rotation directions. The inner and outer wheel hubs are respectively assembled on the corresponding unidirectional bearings and can rotate in the circumferential direction relative to each other when encountering obstacles. The wheel-leg units are uniformly arranged in the circumferential direction and comprise pairs of staggered skeletons and three-stage scissor assemblies connected in sequence. The scissor assemblies are driven to fold and unfold by the relative rotation of the wheel hubs, so that the wheel type and leg type states are switched. The elastic reset members are arranged between adjacent wheel-leg units, are stretched to store energy in the leg type state, and release energy to automatically reset the mechanism to the wheel type state after obstacle crossing. The overall structure is symmetrical and compact, has no redundant components, is easy to design to be small and light, and has both smooth driving and self-adaptive obstacle-crossing capabilities.

Description

Technical Field

[0001] This invention relates to the field of robotics, and in particular to a scissor-type wheel-leg mechanism and a wheel-leg robot capable of bidirectional passive obstacle crossing. Background Technology

[0002] With the increasing demand for unstructured and complex environments such as military reconnaissance, field exploration, and post-disaster rubble search and rescue, the terrain-adaptive mobility of small mobile robots has become a key research focus in the industry. Existing land mobile robot locomotion mechanisms are mainly divided into three typical types: wheeled, legged, and tracked, each with inherent application limitations. Wheeled robots have simple structures, high mobility efficiency, and mature control logic, making them suitable for driving on flat and regular roads. However, due to the wheel contact method, their obstacle-crossing performance and environmental adaptability are poor in undulating terrains such as steps, ditches, and gravel. Tracked robots have a large ground contact area and relatively good passability, but their running resistance and energy consumption are high, and friction losses during turning are significant. Their overall structure is bulky and redundant, making it difficult to meet the requirements for miniaturization and lightweight design. Legged robots, relying on discrete support points, can adapt to complex terrain, exhibiting outstanding posture adjustment and obstacle-crossing capabilities. However, they generally adopt multi-joint, multi-degree-of-freedom configurations, with complex drive mechanisms and reliance on complex control algorithms, resulting in high structural complexity, high control thresholds, and low mobility efficiency.

[0003] Wheel-legged robots combine the advantages of efficient wheeled mobility with the strong obstacle-crossing ability of legged robots. On flat ground, they can move stably and with low energy consumption using their wheeled configuration, and when encountering obstacles, they can switch to a legged configuration to improve their mobility. They have become the preferred solution for small-scale work robots in complex and unknown environments.

[0004] Current wheel-leg mechanisms mostly adopt an active control mode switching architecture, which requires additional configuration of actuators and sensors. This not only increases the overall structural complexity and weight of the machine, but also increases the difficulty of mode switching control and the failure rate. Although some passive wheel-leg structures can achieve self-deformation upon contact with obstacles, the axial component hierarchy is complex. Furthermore, when the wheel leg returns to its wheel form from leg form to wheel form, it needs to rely on the reverse rotation of the drive hub to complete the action, which cannot achieve passive autonomous reset. The continuity of mode switching is poor, making it difficult to adapt to stable passage operations in continuous and complex terrain. Therefore, there is an urgent need to develop a scissor-type wheel-leg mechanism with a simplified structure, bidirectional passive obstacle crossing capability, and automatic reset capability. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the problems of complex design, poor continuity and limited applicable scenarios of passive wheel-leg structure in the prior art, and to provide a scissor-type wheel-leg mechanism and wheel-leg robot that can passively cross obstacles in both directions.

[0006] To solve the above-mentioned technical problems, the present invention provides a scissor-type wheel-leg mechanism capable of bidirectional passive obstacle crossing, which has a wheel-type movement state and a leg-type movement state. It includes: a drive unit comprising a rotary driver and a rotary shaft, the rotary shaft being connected to the power output end of the rotary driver to rotate around its axis; a first one-way bearing and a second one-way bearing mounted on the rotary shaft, the first and second one-way bearings being spaced apart on the rotary shaft and having opposite locking directions; an inner hub and an outer hub, the inner hub being centrally connected to the first one-way bearing, and the outer hub being centrally connected to the second one-way bearing; when blocked by an obstacle, the inner and outer hubs rotating circumferentially relative to each other under the action of the drive unit; and multiple wheel-leg units, each wheel-leg unit being disposed between the inner and outer hubs and evenly spaced around the rotary shaft. The wheel-leg unit includes two frames, a primary scissor lift assembly, a secondary scissor lift assembly, and a tertiary scissor lift assembly. The two frames are arranged opposite each other along the rotation axis and staggered in the thickness direction of the wheel-leg unit. The primary, secondary, and tertiary scissor lift assemblies are sequentially hinged and linked, and are all located between the two frames. The two free ends of the primary scissor lift assembly are respectively hinged to the inner and outer wheel hubs, and the two free ends of the tertiary scissor lift assembly are respectively hinged to the two frames, so as to switch between wheel-type and leg-type movement states when the inner and outer wheel hubs rotate relative to each other in the circumferential direction. Multiple elastic reset members are respectively located between two adjacent wheel-leg units. When the wheel-leg mechanism switches to the leg-type movement state, the elastic reset members are stretched and store energy. After the obstacle resistance disappears, the elastic reset members release energy and pull the wheel-leg unit to automatically reset to the wheel-type movement state.

[0007] In one embodiment of the present invention, the wheel leg unit further includes a transmission assembly, the transmission assembly including two hinged links, each hinged link including a long shaft and a short shaft, the two hinged links being rotatably connected at the inflection point, wherein the end of the long shaft is hinged to the frame, and the middle part of the long shaft is hinged to the third-stage scissor lift assembly, and the short shaft is hinged to the second-stage scissor lift assembly.

[0008] In one embodiment of the present invention, the first-stage scissor lift assembly includes two mutually hinged first-stage links, the second-stage scissor lift assembly includes two mutually hinged second-stage links, and the third-stage scissor lift assembly includes two mutually hinged third-stage links. The ends of the two first-stage links, away from the second-stage scissor lift assembly, are respectively hinged to the inner hub and the outer hub, and the other ends are hinged to the second-stage links. The ends of the third-stage links, away from the second-stage scissor lift assembly, are respectively hinged to the two frames, and the other ends are hinged to the long shaft. One end of each second-stage link is hinged to the first-stage link, and the other end is hinged to the short shaft.

[0009] In one embodiment of the present invention, the skeleton includes a connecting portion and a moving portion. The connecting portion extends from the inside to the outside. The elastic reset member is connected to the connecting portion. The moving portion is fixed to the free end of the connecting portion and is configured as an arc-shaped structure that can support rolling on the moving surface.

[0010] In one embodiment of the present invention, the inner hub is provided with an arc-shaped groove, and the outer hub is provided with a sliding column. The sliding column extends along the thickness direction of the drive unit, with one end fixed to the outer hub and the other end passing through the groove to limit the relative rotation angle between the inner hub and the outer hub.

[0011] In one embodiment of the present invention, the scissor-type wheel leg mechanism includes three wheel leg units, which are arranged in a circumferential ring at 120° intervals around the rotation axis; when the wheel leg mechanism is in a wheel-type movement state, the outer edges of the skeletons of the multiple wheel leg units together form a complete circular wheel outline.

[0012] In one embodiment of the present invention, the first-stage scissor lift assembly, the second-stage scissor lift assembly, and the third-stage scissor lift assembly work together in a coordinated manner. When the inner hub and the outer hub rotate relative to each other in the circumference, the third-stage scissor lift assembly tends to extend, while the first-stage and second-stage scissor lift assemblies tend to contract. The radial extension of the third-stage scissor lift assembly is less than the total radial contraction of the first-stage and second-stage scissor lift assemblies, so that the overall scissor lift assembly forms a radially outward expansion displacement effect, driving the frame to extend outward synchronously to achieve the switch from wheeled movement to legged movement.

[0013] In one embodiment of the present invention, the drive unit further includes a mounting plate, the rotary driver is disposed on the mounting plate, and the mounting plate is connected to an external mobile device. The inner rings of the first one-way bearing and the second one-way bearing are both fixed to the rotating shaft. The inner hub is fixedly sleeved on the outer ring of the first one-way bearing, and the outer hub is fixedly sleeved on the outer ring of the second one-way bearing.

[0014] The present invention provides a wheeled-legged robot, which includes the above-mentioned scissor-type wheeled-legged mechanism capable of bidirectional passive obstacle crossing.

[0015] In one embodiment of the present invention, the wheeled robot further includes a control mechanism connected to a rotary actuator in the bidirectional passive obstacle-crossing scissor-type wheeled robot mechanism.

[0016] The technical solution of the present invention has the following advantages compared with the prior art:

[0017] The scissor-type wheel-leg mechanism and wheel-leg robot capable of bidirectional passive obstacle crossing described in this invention do not require additional deformation drive motors, mode switching sensors, or complex control algorithms. They rely solely on the stopping resistance generated by the contact between the wheel legs and obstacles to drive the inner and outer wheel hubs to rotate circumferentially relative to each other, thereby driving the multi-stage scissor-type components to achieve passive switching from wheeled to legged mode. This purely mechanical adaptive triggering method effectively reduces the complexity of the mechanism, manufacturing costs, and control difficulty, and improves the operational reliability in complex environments.

[0018] By coaxially setting two locking one-way bearings with opposite rotation directions on the rotating shaft, which are respectively connected to the inner and outer wheel hubs for transmission, the passive deployment and deformation of the wheel leg mechanism can be triggered when the robot comes into contact with obstacles during forward and reverse movement. This breaks through the working condition limitations of traditional one-way passive obstacle crossing mechanisms and significantly improves the robot's operational flexibility and terrain adaptability in complex scenarios such as confined spaces and post-disaster ruins.

[0019] Meanwhile, this mechanism stores elastic potential energy when the wheel leg switches to the leg-like state by setting an elastic reset component between adjacent wheel leg units. After the obstacle resistance disappears, the elastic reset component can automatically release the potential energy, pulling the wheel leg unit, scissor lift assembly and inner and outer wheel hubs to reset. Without driving the wheel hubs to rotate in the opposite direction, the mechanism can be restored to the wheel-like movement state. This achieves passive, automatic and continuous completion of mode switching, avoiding the lag and failure risk of active reset control, and adapting to the needs of long-distance, multi-obstacle continuous terrain operation.

[0020] This mechanism employs a structure in which primary, secondary, and tertiary scissor lift components are sequentially hinged and linked, efficiently converting the relative circumferential rotational displacement of the inner and outer hubs into the radial opening and closing displacement of the wheel leg frame. Furthermore, when the circumferential rotation is triggered, the tertiary scissor lift component extends while the primary and secondary scissor lift components retract, creating a net radial outward expansion effect through the displacement difference. This significantly improves the wheel leg mechanism's ultimate obstacle-crossing height and ground clearance, effectively enhancing its obstacle-crossing capability and structural stability in legged mode.

[0021] In summary, this mechanism adopts a pair of wheel leg frames arranged axially and modular wheel leg units evenly distributed circumferentially. The overall structure is symmetrical and compact, with no redundant parts, which facilitates miniaturization and lightweight integration, and takes into account both mobility efficiency and terrain adaptability. Attached Figure Description

[0022] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0023] Figure 1 This is a three-dimensional structural diagram of a scissor-type wheel-leg mechanism capable of bidirectional passive obstacle crossing in a preferred embodiment of the present invention;

[0024] Figure 2 yes Figure 1 The diagram shows a three-dimensional structural schematic of a scissor-type wheel-leg mechanism capable of passively crossing obstacles in both directions, from another perspective.

[0025] Figure 3 yes Figure 1 A three-dimensional structural diagram of the drive unit in the bidirectional passive obstacle-crossing scissor-type wheel-leg mechanism shown.

[0026] Figure 4 yes Figure 1 The diagram shows a three-dimensional structure of the outer hub and multiple wheel leg units in a scissor-type wheel-leg mechanism capable of bidirectional passive obstacle crossing.

[0027] Figure 5 yes Figure 1 The diagram shows a three-dimensional structure of the inner hub and multiple wheel leg units in a scissor-type wheel-leg mechanism that can passively overcome obstacles in both directions.

[0028] Figure 6 yes Figure 5 Enlarged structural diagram at point A in the middle;

[0029] Figure 7 yes Figure 1 The diagram shows a scissor-type wheel-leg mechanism capable of bidirectional passive obstacle crossing in a leg-moving state.

[0030] Figure 8 This is a three-dimensional structural diagram of a wheeled-legged robot according to another embodiment of the present invention;

[0031] Figure 9 yes Figure 8 The diagram shows the structure of the front wheel of the wheeled robot during obstacle crossing.

[0032] Figure 10 yes Figure 7 The diagram shows the structure of the wheeled robot after its front wheels have overcome an obstacle.

[0033] Explanation of reference numerals in the accompanying drawings: 100, drive unit; 110, mounting plate; 120, rotary actuator; 130, rotating shaft; 140, first one-way bearing; 150, second one-way bearing; 200, inner hub; 210, slide groove; 300, outer hub; 310, slide column; 400, wheel leg unit; 410, frame; 411, connecting part; 412, moving part; 420, first-stage scissor lift assembly; 421, first-stage connecting rod; 430, second-stage scissor lift assembly; 431, second-stage connecting rod; 440, third-stage scissor lift assembly; 441, third-stage connecting rod; 450, transmission assembly; 451, hinged connecting rod; 4511, long shaft; 4512, short shaft; 500, elastic return element. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0035] Example 1: See Figures 1 to 7As shown, this embodiment provides a scissor-type wheel-leg mechanism capable of bidirectional passive obstacle crossing, having both wheeled and legged movement states. It includes a drive unit 100, which comprises a rotary driver 120 and a rotating shaft 130. The rotating shaft 130 is connected to the power output end of the rotary driver 120 to rotate around its axis. The rotating shaft 130 is equipped with a first one-way bearing 140 and a second one-way bearing 150, which are spaced apart on the rotating shaft 130. The locking rotation directions are opposite; an inner hub 200 and an outer hub 300, the inner hub 200 being centrally connected to the first one-way bearing 140, and the outer hub 300 being centrally connected to the second one-way bearing 150, when stopped by an obstacle, the inner hub 200 and the outer hub 300 rotate circumferentially relative to each other under the action of the drive unit 100; multiple wheel leg units 400, all of which are disposed between the inner hub 200 and the outer hub 300, and are evenly spaced around the rotation axis 130, any one of the wheel leg units... The wheel 400 includes two frames 410, a primary scissor lift assembly 420, a secondary scissor lift assembly 430, and a tertiary scissor lift assembly 440. The two frames 410 are arranged opposite each other along the rotation axis 130 and are staggered in the thickness direction of the wheel leg unit 400. The primary scissor lift assembly 420, the secondary scissor lift assembly 430, and the tertiary scissor lift assembly 440 are sequentially hinged and linked, and are all located between the two arc-shaped frames 410. The two free ends of the primary scissor lift assembly 420 are respectively hinged to the inner hub 200 and the outer hub 30. 0. The two free ends of the three-stage scissor lift assembly 440 are respectively hinged to the two frames 410 to switch between wheel-type movement and leg-type movement when the inner hub 200 and the outer hub 300 rotate relative to each other in the circumference; multiple elastic reset members 500 are respectively disposed between two adjacent wheel-leg units 400. When the wheel-leg mechanism switches to the leg-type movement state, the elastic reset member 500 is stretched and stores energy. After the obstacle stop resistance disappears, the elastic reset member 500 releases energy and pulls the wheel-leg unit 400 to automatically reset to the wheel-type movement state.

[0036] In this embodiment, the drive unit 100 serves as the overall power input and bidirectional transmission adapter, the rotary driver 120 provides rotational driving power for the entire wheel leg mechanism, and the rotary shaft 130 is used to transmit power and provide a coaxial mounting reference for each bearing and wheel hub. The rotary shaft 130 is equipped with a first one-way bearing 140 and a second one-way bearing 150 with opposite locking directions. When the rotary shaft 130 rotates forward, the outer wheel hub 300 is locked and the inner wheel hub 200 rotates freely. At the same time, when it rotates in reverse, the inner wheel hub 200 is locked and the outer wheel hub 300 rotates freely. This provides a transmission basis for the mechanism to passively trigger obstacle crossing in both forward and reverse directions. Relying on the one-way locking and reverse rotation characteristics of the one-way bearings, the prerequisite for the inner and outer wheel hubs to generate circumferential relative rotation is constructed.

[0037] Furthermore, the drive unit 100 also includes a mounting plate 110, on which the rotary driver 120 is disposed, and the mounting plate 110 is connected to an external mobile device. The inner rings of the first one-way bearing 140 and the second one-way bearing 150 are both fixed to the rotating shaft 130. The inner hub 200 is fixedly sleeved on the outer ring of the first one-way bearing 140, and the outer hub 300 is fixedly sleeved on the outer ring of the second one-way bearing 150. The mounting plate 110 provides a stable mounting support for the rotary driver 120, and can also be integrally connected and fixed to the external mobile device to achieve the overall assembly positioning and load-bearing fixation of the entire wheel leg mechanism. The rotary driver 120 is reliably deployed on the mounting plate 110 and outputs rotational power to drive the rotating shaft 130 to rotate synchronously.

[0038] The inner rings of the first one-way bearing 140 and the second one-way bearing 150 are both fixedly connected to the rotating shaft 130, and can rotate synchronously and in the same direction with the rotating shaft 130. Utilizing the structural characteristics of the two one-way bearings locking in opposite directions of rotation, the inner hub 200 and the outer hub 300 are respectively driven and matched through their respective outer rings. The inner hub 200 is fixedly sleeved on the outer ring of the first one-way bearing 140, and the outer hub 300 is fixedly sleeved on the outer ring of the second one-way bearing 150. This allows the rotating shaft 130 to selectively drive the inner hub 200 or the outer hub 300 to rotate synchronously when rotating in both directions. Specifically, when the rotating shaft 130 rotates in the forward direction, it drives the outer hub 300 to rotate, and when the rotating shaft 130 rotates in the reverse direction, it drives the inner hub 200 to rotate. This creates a circumferential speed difference and relative rotation between the inner and outer hubs when encountering obstacles, providing a stable power transmission and motion coordination basis for the subsequent linkage folding and unfolding of the scissor lift assembly, the bidirectional passive obstacle crossing of the wheel leg mechanism, and mode switching.

[0039] In this embodiment, the inner hub 200 and the outer hub 300 serve as intermediate transmission load-bearing bodies, respectively assembled and connected with corresponding one-way bearings, undertaking the functions of power transfer, hinge support, and motion limitation. When the robot encounters obstacles and generates stopping resistance, the transmission difference of the one-way bearings enables the inner hub 200 and the outer hub 300 to generate controllable circumferential relative rotation, converting the rotational motion of the drive unit 100 into relative angular displacement between the two hubs. At the same time, it provides fixed hinge mounting points for each group of wheel leg units 400 and scissor fork assembly, and is the core motion base for realizing the opening and closing deformation of the scissor fork mechanism and completing the wheel leg mode switching.

[0040] Furthermore, the inner hub 200 is provided with an arc-shaped groove 210, and the outer hub 300 is provided with a sliding column 310. The sliding column 310 extends along the thickness direction of the drive unit 100, with one end fixed to the outer hub 300 and the other end passing through the groove 210 to limit the relative rotation angle between the inner hub 200 and the outer hub 300. By setting an arc-shaped groove 210 in the inner hub 200 and a corresponding sliding column 310 in the outer hub 300, the sliding column 310 slides through the arc-shaped groove 210, forming a sliding limit structure between the inner and outer hubs. The arc length of the arc-shaped groove 210 limits the maximum relative rotation angle between the inner hub 200 and the outer hub 300. This ensures that the inner and outer hubs have sufficient relative rotation stroke to drive the multi-stage scissor lift assembly to smoothly unfold and complete the switch from wheeled to legged mode when the robot encounters an obstacle. It also effectively limits excessive relative rotation between the two hubs, avoiding problems such as overtravel, mechanism interference, jamming, or deformation damage to the scissor lift linkage, frame 410, and other structures. At the same time, it can precisely constrain the extension range of the wheel legs, so that the wheel leg mechanism always maintains a stable and standardized folding and unfolding motion trajectory, improving the overall mechanism's motion stability and structural reliability, and ensuring a smooth and controllable wheel leg mode switching process.

[0041] In this embodiment, multiple wheel-leg units 400 serve as the main body for deformation execution and obstacle crossing support of the wheel-leg mechanism. They are evenly spaced along the rotation axis 130 to ensure overall force and motion symmetry. The two skeletons 410 in a single wheel-leg unit 400 constitute the outer edge support contour in the wheel-like state and the obstacle crossing support foot in the leg-like state. They are arranged in pairs axially and staggered in the thickness direction to ensure that the opening and closing movements do not interfere with each other and the assembly structure is compact.

[0042] Specifically, the scissor-type wheel-leg mechanism in this embodiment includes three wheel-leg units 400, which are arranged in a circumferential ring at 120° intervals around the rotation axis 130. When the wheel-leg mechanism is in wheel-like movement, the outer edges of the skeletons 410 of the multiple wheel-leg units 400 together form a complete circular wheel outline. The three wheel-leg units 400 enable the overall wheel-leg mechanism to have a balanced force distribution and symmetrical movement posture, effectively avoiding the situation of concentrated load on one side, and improving the stability of the mechanism's operation and the overall rigidity of the structure. When the wheel-leg mechanism is in wheel-like movement, the outer edges of the skeletons 410 of each wheel-leg unit 400 cooperate with each other to form a complete circular wheel outline, which can ensure that the robot has a regular wheel shape when traveling on flat roads, achieving smooth and low-resistance rolling. At the same time, the regular circular layout can allow each wheel-leg unit 400 to be passively deployed synchronously when encountering obstacles, further enhancing the stability and adaptability when traversing complex terrain. In different implementations, the wheel leg units 400 can be configured in different numbers according to actual needs, and the present invention does not impose specific limitations on this.

[0043] In this embodiment, the first-stage scissor lift assembly 420, the second-stage scissor lift assembly 430, and the third-stage scissor lift assembly 440 are sequentially hinged to form a multi-stage folding and unfolding transmission chain. The first-stage scissor lift assembly 420 is hinged to the inner and outer wheel hubs as the motion input end, and the third-stage scissor lift assembly 440 is hinged to the frame 410 as the motion output end. The relative circumferential rotation of the inner and outer wheel hubs can be converted into the linkage opening and closing motion of the scissor lift assembly. During the relative rotation, the third-stage scissor lift assembly 440 extends while the first-stage scissor lift assembly 420 and the second-stage scissor lift assembly 430 retract. Relying on the displacement difference that the total radial extension is less than the retraction, the pair of frames 410 are driven to open outward while retracting towards each other, reliably realizing the adaptive switching between wheeled movement and legged movement. At the same time, the multi-stage scissor lift linkage can improve the overall structural strength and obstacle crossing support stability.

[0044] Furthermore, in this embodiment, the first-stage scissor lift assembly 420, the second-stage scissor lift assembly 430, and the third-stage scissor lift assembly 440 are linked and cooperate. When the inner hub 200 and the outer hub 300 rotate relative to each other in the circumference, the third-stage scissor lift assembly 440 tends to extend, while the first-stage scissor lift assembly 420 and the second-stage scissor lift assembly 430 tend to contract. The radial extension of the third-stage scissor lift assembly 440 is less than the total radial contraction of the first-stage scissor lift assembly 420 and the second-stage scissor lift assembly 430, so that the entire scissor lift assembly forms a radially outward expansion displacement effect, driving the frame 410 to extend outward synchronously to achieve the switch from wheeled movement state to legged movement state. The primary scissor lift assembly 420, secondary scissor lift assembly 430, and tertiary scissor lift assembly 440 are hinged together to form a complete force transmission and folding system. During the circumferential relative rotation of the inner hub 200 and the outer hub 300, the tertiary scissor lift assembly 440 extends in accordance with the linkage, while the primary scissor lift assembly 420 and the secondary scissor lift assembly 430 simultaneously contract. The radial extension of the tertiary scissor lift assembly 440 is less than the total radial contraction of the primary scissor lift assembly 420 and the secondary scissor lift assembly 430. This difference in displacement between extension and contraction causes the entire scissor lift assembly to expand radially outward, thereby synchronously driving a pair of frames 410 to expand outward while contracting towards each other. This smoothly and reliably converts the circumferential rotational displacement of the inner and outer hubs into the radial opening displacement of the frames 410, successfully completing the adaptive switching of the wheel-leg mechanism from wheel-type movement to leg-type movement. At the same time, the linkage of each scissor lift ensures smooth and interference-free movement during the folding process, improving the stability of the mechanism mode switching and the obstacle-crossing support effect.

[0045] Specifically, the wheel leg unit 400 further includes a transmission assembly 450, which includes two hinged links 451. Each hinged link 451 includes a long shaft 4511 and a short shaft 4512. The two hinged links 451 are rotatably connected at their inflection points. The end of the long shaft 4511 is hinged to the frame 410, and the middle of the long shaft 4511 is hinged to the third-stage scissor lift assembly 440. The short shaft 4512 is hinged to the second-stage scissor lift assembly 430. The transmission assembly 450 serves as an intermediate transmission transition structure between the secondary scissor lift assembly 430, the tertiary scissor lift assembly 440, and the frame 410. It consists of two hinged connecting rods 451. In this embodiment, the long shaft 4511 and short shaft 4512 of each hinged connecting rod 451 are integrally formed, with an included angle of 78° between them. The two hinged connecting rods 451 rotate relative to each other at their own inflection points to form a movable hinge fulcrum. Utilizing the multi-point connection of hinged connections—with the end of the long shaft 4511 hinged to the frame 410, the middle of the long shaft 4511 hinged to the tertiary scissor lift assembly 440, and the short shaft 4512 hinged to the secondary scissor lift assembly 430—precise transmission can be achieved. The linkage displacement and force between the secondary scissor lift assembly 430 and the tertiary scissor lift assembly 440 achieve a reasonable conversion of motion direction and a smooth transition of torque, constraining the motion trajectory of each stage of the scissor lift assembly. This ensures that the secondary scissor lift assembly 430 and the tertiary scissor lift assembly 440 move synchronously and without deviation or jamming during the telescopic linkage process. This precisely transmits the opening and closing motion of the scissor lift assembly to the frame 410, allowing the frame 410 to complete radial expansion and contraction in a regular manner with the scissor lift's folding and extending motion. Simultaneously, the structural layout of the long axis 4511 and the short axis 4512 enhances the structural strength and motion constraint capability of the transmission assembly 450, ensuring smooth, stable, and regular folding and extending motion of the wheel leg unit 400. This invention does not specifically limit the exact connection position between the long axis 4511 and the short axis 4512.

[0046] Further, the first-stage scissor lift assembly 420 includes two hinged first-stage links 421, the second-stage scissor lift assembly 430 includes two hinged second-stage links 431, and the third-stage scissor lift assembly 440 includes two hinged third-stage links 441. The ends of the two first-stage links 421 away from the second-stage scissor lift assembly 430 are respectively hinged to the inner hub 200 and the outer hub 300, and the other ends are hinged to the second-stage links 431. The ends of the third-stage links 441 away from the second-stage scissor lift assembly 430 are respectively hinged to the two frames 410, and the other ends are hinged to the long shaft 4511. One end of the second-stage link 431 is hinged to the first-stage link 421, and the other end is hinged to the short shaft 4512.

[0047] The hinged joints at the middle of the same-level connecting rods form a stable scissor lift joint, providing a structural basis for the opening, closing, and telescopic movements of each stage of the assembly. The outer ends of the first-level connecting rod 421 are respectively hinged to the inner hub 200 and the outer hub 300, serving as the power input end of the entire scissor drive mechanism. It can directly receive the displacement and torque caused by the relative circumferential rotation of the inner and outer hubs. The inner end of the first-level connecting rod 421 is connected to the second-level connecting rod 431 to achieve the step-by-step transmission of motion. The two ends of the second-level connecting rod 431 are respectively connected to the short shaft 4512 of the first-level connecting rod 421 and the transmission assembly 450, playing the role of transferring force and transitioning motion postures. The outer ends of the third-level connecting rod 441 are respectively hinged to the two frames 41. The power output end is formed on the top. The inner end of the third-stage connecting rod 441 is hinged to the long shaft 4511 of the transmission component 450, thereby accurately transmitting the linkage extension and retraction motion of the second-stage scissor lift assembly 430 and the third-stage scissor lift assembly 440 to the frame 410 through the transmission component 450. This makes the scissor lift assemblies of each stage form a closed-loop transmission link that is linked sequentially from top to bottom. This ensures that the relative rotation angle of the inner and outer hubs can be orderly converted into the opening and closing action of the scissor lift and the radial folding action of the frame 410. The motion transmission is smooth and the force distribution is uniform, effectively avoiding linkage movement deviation and mechanism interference. This ensures that the wheel-leg mechanism moves synchronously, smoothly and reliably during the switching between wheeled and legged movement states.

[0048] In this embodiment, the frame 410 includes a connecting portion 411 and a moving portion 412. The connecting portion 411 extends from the inside to the outside, specifically configured such that one end is located near the rotation axis, and the other end extends towards the edge of the inner hub 200 / outer hub 300. The elastic reset member 500 is connected to the connecting portion 411. The moving portion 412 is fixed to the free end of the connecting portion 411 and is configured as an arc-shaped structure that can support rolling on the moving surface. The connecting portion 411 serves as the main bearing base of the frame 410, providing radial extension support for the overall structure, and also provides a reliable installation connection point for the elastic reset member 500, facilitating the fixed connection of the elastic reset member 500 between adjacent frames 410 to complete the energy storage and reset traction functions. The moving part 412 is fixedly installed at the free end of the connecting part 411 and adopts an arc-shaped structure. The arc-shaped structure can fit the moving surface to achieve stable rolling support in the wheel-type movement state, ensuring smooth and low-resistance movement on flat roads. When switching to the leg-type movement state, the arc shape can form a stable multi-point support contact, improving the support stability and force balance during obstacle crossing. The whole unit, through the cooperation of the connecting part 411 and the moving part 412, simultaneously takes into account multiple functions such as structural connection, elastic component assembly, road rolling support, and obstacle crossing load.

[0049] In this embodiment, multiple elastic reset components 500 are arranged between adjacent wheel-leg units 400, mainly serving the functions of elastic energy storage and passive automatic reset. When the wheel-leg mechanism switches from wheeled mode to legged obstacle-crossing mode, the elastic reset component 500 is stretched and stores elastic potential energy, reserving power for subsequent reset. After the robot overcomes the obstacle, the obstacle's resistance to the wheel-legs disappears, the elastic reset component 500 releases elastic potential energy, pulling the adjacent wheel-leg unit 400 and frame 410 back to their original positions, causing the scissor lift components at each level to retract in the opposite direction, and the inner wheel hub 200 and outer wheel hub 300 to rotate relative to each other. This allows the entire wheel-leg mechanism to automatically reset to the wheeled movement state without additional drive control, ensuring the continuity and adaptability of wheel-leg mode switching under complex continuous terrain.

[0050] Example 2: This example provides a wheeled-legged robot, see [link to example]. Figures 8 to 10 As shown, it includes the bidirectional passive obstacle-crossing scissor-wheel mechanism described in Embodiment 1 and a control mechanism, wherein the control mechanism is connected to the rotary driver 120 in the bidirectional passive obstacle-crossing scissor-wheel mechanism.

[0051] In summary, the bidirectional passive obstacle-crossing scissor-type wheel-leg mechanism and wheel-leg robot described in this invention do not require additional deformation drive motors, mode switching sensors, or complex control algorithms. They rely solely on the stopping resistance generated by the contact between the wheel legs and obstacles to drive the inner wheel hub 200 and the outer wheel hub 300 to rotate circumferentially relative to each other, thereby driving the multi-stage scissor-type components to work together and achieve passive switching from wheeled to legged mode. This purely mechanical adaptive triggering method effectively reduces the complexity of the mechanism, manufacturing costs, and control difficulty, and improves the operational reliability in complex environments.

[0052] By coaxially setting two locking one-way bearings with opposite rotation directions on the rotating shaft 130, which are respectively connected to the inner hub 200 and the outer hub 300 for transmission, the passive deployment and deformation of the wheel leg mechanism can be triggered when the robot comes into contact with obstacles during forward and reverse movement. This breaks through the working condition limitations of traditional one-way passive obstacle crossing mechanisms and significantly improves the robot's operational flexibility and terrain adaptability in complex scenarios such as confined spaces and post-disaster ruins.

[0053] Meanwhile, this mechanism stores elastic potential energy when the wheel legs switch to the leg-like state through the elastic reset component 500 set between adjacent wheel leg units 400. After the obstacle stop resistance disappears, the elastic reset component 500 can automatically release the potential energy, pulling the wheel leg unit 400, scissor assembly, inner wheel hub 200 and outer wheel hub 300 to reset. Without driving the wheel hub to rotate in the opposite direction, the mechanism can be restored to the wheel-like movement state. This realizes the passive, automatic and continuous completion of mode switching, avoids the lag and failure risk of active reset control, and is suitable for long-distance, multi-obstacle continuous terrain operation needs.

[0054] This mechanism employs a structure in which the first-stage scissor lift assembly 420, the second-stage scissor lift assembly 430, and the third-stage scissor lift assembly 440 are sequentially hinged and linked. This efficiently converts the circumferential relative rotational displacement of the inner hub 200 and the outer hub 300 into the radial opening and closing displacement of the wheel leg frame 410. Furthermore, when the circumferential rotation is triggered, the third-stage scissor lift assembly 440 extends while the first-stage and second-stage scissor lift assemblies 420 and 430 retract. Through the displacement difference, a net radial outward expansion effect is formed, which significantly improves the wheel leg mechanism's ultimate obstacle-crossing height and ground clearance, effectively enhancing its obstacle-crossing ability and structural stability in legged mode.

[0055] In summary, this mechanism adopts a pair of axially arranged wheel leg frames 410 and circumferentially distributed modular wheel leg units 400. The overall structure is symmetrical and compact, with no redundant parts, which facilitates miniaturization and lightweight integration, and takes into account both mobility efficiency and terrain adaptability.

[0056] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A scissor-type wheel-leg mechanism capable of bidirectional passive obstacle crossing, characterized in that: It has both wheeled and legged mobility modes, including: The drive unit includes a rotary driver and a rotary shaft. The rotary shaft is connected to the power output end of the rotary driver to rotate around its axis. The rotary shaft is provided with a first one-way bearing and a second one-way bearing. The first one-way bearing and the second one-way bearing are arranged at intervals on the rotary shaft and have opposite locking rotation directions. The inner hub and the outer hub are connected to the first one-way bearing at their center and to the second one-way bearing at their center. When blocked by an obstacle, the inner hub and the outer hub rotate relative to each other circumferentially under the action of the drive unit. Multiple wheel leg units are disposed between the inner wheel hub and the outer wheel hub, and are evenly spaced around the rotation axis. Each wheel leg unit includes a transmission assembly, two frames, a first-stage scissor lift assembly, a second-stage scissor lift assembly, and a third-stage scissor lift assembly. The two frames are arranged opposite each other along the rotation axis and are staggered in the thickness direction of the wheel leg unit. The transmission assembly includes two hinged links, each hinged link including a long axis and a short axis. The two hinged links are rotatably connected at their inflection points, and the end of the long axis is hinged to... The frame has its long axis hinged to the third-stage scissor lift assembly, and its short axis hinged to the second-stage scissor lift assembly. The first-stage scissor lift assembly, the second-stage scissor lift assembly, and the third-stage scissor lift assembly are sequentially hinged and linked together, and are all disposed between two frames. The two free ends of the first-stage scissor lift assembly are respectively hinged to the inner hub and the outer hub, and the two free ends of the third-stage scissor lift assembly are respectively hinged to the two frames, so as to switch between wheel-type movement and leg-type movement when the inner hub and the outer hub rotate relative to each other in the circumferential direction. The first-stage, second-stage, and third-stage scissor lift components work in tandem. When the inner and outer hubs rotate relative to each other in the circumference, the third-stage scissor lift component tends to extend, while the first-stage and second-stage scissor lift components tend to contract. The radial extension of the third-stage scissor lift component is less than the total radial contraction of the first-stage and second-stage scissor lift components, resulting in a radially outward expansion displacement effect for the entire scissor lift component. This drives the frame to extend outward synchronously, enabling a switch from wheeled movement to legged movement. Multiple elastic reset elements are respectively disposed between two adjacent wheel leg units. When the wheel leg mechanism switches to the leg movement state, the elastic reset elements are stretched and stored energy. After the obstacle stop resistance disappears, the elastic reset elements release energy and pull the wheel leg unit to automatically reset to the wheel movement state.

2. The scissor-type wheel-leg mechanism capable of bidirectional passive obstacle crossing according to claim 1, characterized in that: The first-stage scissor lift assembly includes two hinged first-stage links, the second-stage scissor lift assembly includes two hinged second-stage links, and the third-stage scissor lift assembly includes two hinged third-stage links. In this configuration, the two primary links are respectively hinged at one end to the inner hub and the outer hub of the secondary scissor lift assembly, and the other end is hinged to the secondary link; the tertiary link is respectively hinged at one end to the two frames of the secondary scissor lift assembly, and the other end is hinged to the long shaft; one end of the secondary link is hinged to the primary link, and the other end is hinged to the short shaft.

3. The scissor-type wheel-leg mechanism capable of bidirectional passive obstacle crossing according to claim 1, characterized in that: The frame includes a connecting part and a moving part. The connecting part extends from the inside to the outside. The elastic reset member is connected to the connecting part. The moving part is fixed to the free end of the connecting part and is configured as an arc-shaped structure that can support rolling on the moving surface.

4. The scissor-type wheel-leg mechanism capable of bidirectional passive obstacle crossing according to claim 1, characterized in that: The inner hub is provided with an arc-shaped groove, and the outer hub is provided with a sliding column. The sliding column extends along the thickness direction of the drive unit, with one end fixed to the outer hub and the other end passing through the groove to limit the relative rotation angle between the inner hub and the outer hub.

5. The scissor-type wheel-leg mechanism capable of bidirectional passive obstacle crossing according to claim 1, characterized in that: The scissor-type wheel-leg mechanism includes three wheel-leg units, which are arranged in a circumferential ring at 120° intervals around the rotation axis. When the wheel-leg mechanism is in a wheel-movement state, the outer edges of the skeletons of the multiple wheel-leg units together form a complete circular wheel outline.

6. The scissor-type wheel-leg mechanism capable of bidirectional passive obstacle crossing according to claim 1, characterized in that: The drive unit also includes a mounting plate, the rotary driver is disposed on the mounting plate, and the mounting plate is connected to an external mobile device. The inner rings of the first one-way bearing and the second one-way bearing are both fixed to the rotating shaft. The inner hub is fixedly sleeved on the outer ring of the first one-way bearing, and the outer hub is fixedly sleeved on the outer ring of the second one-way bearing.

7. A wheeled-legged robot, characterized in that: Includes the scissor-type wheel-leg mechanism capable of bidirectional passive obstacle crossing as described in any one of claims 1 to 6.

8. The wheeled robot according to claim 7, characterized in that: The wheeled robot also includes a control mechanism, which is connected to the rotary actuator in the bidirectional passive obstacle-crossing scissor-type wheeled robot.

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