A hinge-driven bistable wheel-leg conversion mechanism

Abstract

The present invention relates to the technical field of robot compliant motion system design, and discloses a hinge-driven bistable wheel-leg conversion mechanism, comprising a bistable structure having two stable states: a wheel shape and a leg shape. The bistable structure comprises a frame and a first drive module. The frame comprises a plurality of spokes distributed in an array, a hinge and a pseudo-rigid rod are provided between the ends of two adjacent spokes, and the hinge is connected to the first drive module. The hinge bends and deforms under the positive action of the first drive module, and the bistable structure is converted from a wheel shape to a leg shape. When the first drive module stops acting, the hinge returns to its original state, and the bistable structure returns from a leg shape to a wheel shape. The stiffness of the pseudo-rigid rod is greater than the stiffness of the hinge. The present invention can undergo flexible deformation when encountering obstacles, thereby adapting to various unstructured terrain environments and having better buffering and energy absorption characteristics.

Description

Technical Field

[0001] The invention belongs to the technical field of robot compliant movement system design, and relates to a hinge-driven bistable wheel-leg conversion mechanism. Background Art

[0002] In recent years, with the rapid development of advanced technologies such as mechatronics, control science, materials technology, and artificial intelligence, robotics, a product of the cross-disciplinary integration of multiple disciplines, has achieved unprecedented progress and gained widespread application. It has gradually transitioned from initial theoretical research to practical product development. As a key component of robotics technology, mobile robots play an indispensable role. They play a crucial role in exploration and reconnaissance missions in unknown terrain. Compared to human operators performing tasks such as terrain exploration, deep space exploration, and battlefield reconnaissance, mobile robots not only reduce risk but also significantly save costs.

[0003] Traditional mobile robots with a single locomotion mode face limitations when navigating complex terrain and obstacles. These traditional robots lack the ability to adapt to diverse environments and overcome obstacles, resulting in reduced efficiency when performing tasks on unstructured surfaces, which in turn impacts the mobile robots' ability to complete tasks. In recent years, wheel-to-leg transformable robots have been widely researched due to their exceptional performance. A variety of different robotic mechanisms have been designed to address diverse operating environments and performance requirements, including structures suitable for environments such as flat land, deserts, and extraterrestrial environments, featuring high load capacity or exceptional flexibility. Many of these robots also employ bistable structures, which achieve wheel-to-leg transformation and jumping through the storage and release of elastic potential energy.

[0004] Furthermore, domestic research currently focuses primarily on achieving predetermined functions, while further research is needed on key technical areas such as the combined optimization of multiple motion modes, the design theory of special-shaped and deformable wheels, and the performance of a single motion mode. Furthermore, there is currently little integration with bistable structures, so the application of flexible design in wheel-leg conversion mechanisms is of great research significance. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention provides a hinge-driven bistable wheel-leg conversion mechanism that can undergo flexible deformation when encountering obstacles, thereby adapting to various unstructured terrain environments and having better buffering and energy absorption characteristics.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] In the first aspect, the present invention proposes a hinge-driven bistable wheel-leg conversion mechanism, including a bistable structure with two stable states, wheel shape and leg shape, the bistable structure including a frame and a first drive module, the frame including a plurality of spokes distributed in an array, a hinge and a pseudo-rigid rod are arranged between the ends of two adjacent spokes, and the hinge is connected to the first drive module; the hinge bends and deforms under the positive action of the first drive module, so that after the angle between the spoke connected by the hinge and the pseudo-rigid rod reaches above the critical deformation angle, the bistable structure is converted from a wheel shape to a leg shape, and when the first drive module stops, the hinge returns to its original state, so that after the angle between the spoke connected by the hinge and the pseudo-rigid rod reaches below the critical deformation angle, the bistable structure is restored from a leg shape to a wheel shape; the stiffness of the pseudo-rigid rod is greater than the stiffness of the hinge.

[0008] In combination with the first aspect, further, the hinge includes a first hinge and a second hinge, the two ends of the second hinge are respectively connected to one end of a pseudo-rigid rod, the other end of the pseudo-rigid rod is respectively connected to one end of the first hinge, and the other end of the first hinge is connected to the end of the spoke.

[0009] In combination with the first aspect, further, the first hinge and the second hinge have opposite deformation and bending directions, the first hinge becomes an outward convex shape when deformed, and the second hinge becomes an inward convex shape when deformed.

[0010] In combination with the first aspect, further, the wheel-leg conversion mechanism of the present invention also includes a vehicle body, a rotating shaft, a second drive module for driving the start and stop and driving speed of the wheel-leg conversion mechanism, a control module for controlling the shape of the bistable structure, and an auxiliary module for exploring the external environment and feeding back the exploration results to the control module; the rotating shaft is connected to the frame of the bistable structure; the second drive module is connected to the rotating shaft, and is used to drive the rotating shaft to rotate, thereby driving the bistable structure to rotate as a whole; the control module is respectively communicated with the first drive module, the second drive module and the auxiliary module, and is used to receive the collected information sent by the auxiliary module, and send control instructions to the first drive module and the second drive module.

[0011] In combination with the first aspect, further, when the material of the hinge is polycarbonate-type shape memory polyurethane or liquid crystal elastomer, and the material of the pseudo-rigid rod is polypropylene, the first driving module is a resistance wire.

[0012] In combination with the first aspect, further, when the hinge is a silicone pneumatic structure and the material of the pseudo-rigid rod is polypropylene, the first driving module includes an air pump and an air duct connected to each other, and the air duct is connected to the hinge.

[0013] In a second aspect, the present invention provides a hinge-driven bistable wheel-leg conversion mechanism, comprising a bistable structure having two stable states, namely, a wheel shape and a leg shape, wherein the bistable structure comprises a frame and a first drive module; the frame comprises a plurality of spokes distributed in an array, a hinge and a pseudo-rigid rod are provided between the ends of two adjacent spokes, the hinge comprises a first hinge and a second hinge, and the pseudo-rigid rod comprises a first pseudo-rigid rod and a second pseudo-rigid rod; the first hinge is provided at the end of the spoke, one end of the first pseudo-rigid rod is fixedly connected to the first hinge, and the other end is connected to one end of the second hinge, The other end of the second hinge is connected to one end of the second pseudo-rigid rod, and the other end of the second pseudo-rigid rod is directly hinged to the adjacent spoke; the first hinge is connected to the first drive module; the first hinge rotates under the positive action of the first drive module, and when the angle between the first pseudo-rigid rod and the spoke with the first hinge connected to the end increases to the critical deformation angle, the bistable structure is converted from a wheel shape to a leg shape, and when the first drive module is reversed, when the angle between the first pseudo-rigid rod and the spoke with the first hinge connected to the end decreases below the critical deformation angle, the bistable structure recovers from a leg shape to a wheel shape.

[0014] In combination with the second aspect, further, the length of the second pseudo-rigid rod is greater than that of the first pseudo-rigid rod.

[0015] In combination with the second aspect, further, the wheel-leg conversion mechanism of the present invention also includes a vehicle body, a rotating shaft, a second drive module for driving the start and stop and driving speed of the wheel-leg conversion mechanism, a control module for controlling the shape of the bistable structure, and an auxiliary module for exploring the external environment and feeding back the exploration results to the control module; the rotating shaft is connected to the frame of the bistable structure; the second drive module is connected to the rotating shaft for driving the rotating shaft to rotate, thereby driving the bistable structure to rotate as a whole; the control module is respectively communicated with the first drive module, the second drive module and the auxiliary module, for receiving the collected information sent by the auxiliary module, and sending control instructions to the first drive module and the second drive module.

[0016] In combination with the second aspect, further, the first hinge is a pulley, the first driving module includes a motor and a rope, the motor drives the pulley to rotate through the rope, and the motor is connected to the control module.

[0017] In combination with the first aspect or the second aspect, further, the bistable structure is integrally formed or 3D printed, or the hinge is fixedly connected to the pseudo-rigid rod and the spokes of the frame respectively.

[0018] In combination with the first aspect or the second aspect, further, the number of the spokes is 3 to 5.

[0019] Compared with the prior art, the present invention provides a hinge-driven bistable wheel-leg conversion mechanism, which has the following beneficial effects:

[0020] (1) The wheel-leg conversion mechanism of the present invention has a flexible structure, which can undergo flexible deformation when encountering obstacles, thereby adapting to various unstructured terrain environments and having better buffering and energy absorption characteristics.

[0021] (2) The wheel-leg conversion mechanism of the present invention is driven by a hinge and can actively convert between wheel shape and leg shape by controlling the bending deformation or relative rotation of the hinge part. By combining the deformation modes of each spoke, a richer deformation mode can be formed, thereby improving the adaptability of the mobile robot or car equipped with the wheel-leg conversion mechanism of the present invention to the environment.

[0022] (3) The present invention applies a bistable structure in the wheel-leg conversion mechanism, so the configuration change is rapid and the configuration stability is high.

[0023] (4) The bistable structure adopts the design method of pseudo-rigid body model, simulating the deformation of flexible components by the relative motion of rigid components, conforming to the future development trend of compliant robot technology, and promoting the application of compliant structures in the field of mobile robots. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the main structure of the bistable structure in Example 1 of the present invention;

[0025] Figure 2 is a schematic diagram of the three-dimensional structure of the bistable structure in Example 1 of the present invention;

[0026] Figure 3 Schematic diagram of the deformation principle of the bistable structure in Example 1 of the present invention;

[0027] Figure 4 Schematic diagram of six deformation modes of the bistable structure in Example 1 of the present invention, which are Figure 4 a to Figure 4 f;

[0028] Figure 5 Schematic diagram of the three-dimensional structure of the compliant bistable wheel-leg conversion mechanism in Example 1 of the present invention;

[0029] Figure 6 1 is a bottom view schematic diagram of the structure of the compliant bistable wheel-leg conversion mechanism in Example 1 of the present invention;

[0030] Figure 7 is a torque-displacement curve diagram of the bistable structure under torque loading in Example 1 of the present invention;

[0031] Figure 8 is a strain energy-displacement curve diagram of the bistable structure under torque loading in Example 1 of the present invention;

[0032] Figure 9 is a force-displacement curve diagram of the bistable structure under obstacle force loading in Example 1 of the present invention;

[0033] Figure 10 is a structural characteristic diagram of the bistable structure in Example 1 of the present invention, wherein: Figure 10 a is the strain energy-displacement curve of the bistable structure, Figure 10 b is the equivalent stress-displacement curve of the bistable structure;

[0034] Figure 11 This is a schematic diagram of the material selection process for the bistable structure in Example 1 of the present invention;

[0035] Figure 12 : is a structural introduction diagram of the bistable structure in Example 2 of the present invention, wherein: Figure 12 a is a simplified schematic diagram of the main structure of the bistable structure. Figure 12 b is a schematic diagram of the deformation principle of the bistable structure;

[0036] Figure 13 : is a structural introduction diagram of the bistable structure in Example 3 of the present invention, wherein: Figure 13 a is a simplified schematic diagram of the main structure of the bistable structure in Example 3 of the present invention, Figure 13 b is a schematic diagram of the deformation principle of the bistable structure in Example 3 of the present invention;

[0037] Figure 14 is a schematic diagram of the three-dimensional structure of the bistable structure in Example 4 of the present invention;

[0038] Figure 15 Schematic diagram of four deformation modes of the bistable structure in Example 4 of the present invention, which are Figure 15 a to Figure 15 d.

[0039] The meanings of the reference numerals in the figures are:

[0040] 1-body; 2-rotating shaft; 3-bistable structure; 4-second drive module; 5-control module; 6-frame; 7-hinge; 71-first hinge; 72-second hinge; 8-pseudo-rigid rod; 81-first pseudo-rigid rod; 82-second pseudo-rigid rod; 9-first drive module; 91-rope; 92-pulley; 10-auxiliary module. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0042] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present invention. Meanwhile, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to actual proportional relationships. Technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may also include different values. It should be noted that similar numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0043] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the protection content of the present invention.

[0044] Example 1

[0045] like Figure 5 and Figure 6 As shown, this embodiment proposes a hinge-driven, compliant bistable wheel-leg conversion mechanism, comprising a vehicle body 1, a rotating shaft 3, a bistable structure 3 connected to the rotating shaft 3, a second drive module 4 for driving the wheel-leg conversion mechanism, a control module 5 for controlling the shape of each bistable structure 3, and an auxiliary module 10 for detecting the external environment and feeding back the detection results to the control module 5. The auxiliary module 10 is disposed on the upper portion of the vehicle body; the second drive module 4 and the control module 5 are respectively disposed on the lower portion of the vehicle body 1; and a bistable structure 3 is connected to each end of the rotating shaft 3. The second drive module 4 is connected to the rotating shaft 3 and includes equipment such as a motor and a power supply, which is used to drive the rotating shaft 3 to rotate, thereby driving the bistable structure 3 to rotate.

[0046] like Figure 5As shown, the auxiliary module 10 includes a variety of electronic instruments and is equipped with corresponding equipment according to actual task requirements, such as radars, cameras, LED lights and other electronic instruments to explore and feedback the external environment, and transmit the collected information to the control module 5, thereby improving the ability to perform tasks.

[0047] like Figures 1 to 4 As shown, the bistable structure 3 of this embodiment has two stable states, namely a wheel shape and a leg shape. It includes a frame 6 with four spokes, 12 low-rigidity hinges 7 and 8 for controlled bending deformation, a high-rigidity pseudo-rigid rod 8 for energy storage and release, and a first drive module 9 that passes through the hinge 7 and pseudo-rigid rod 8. The rotating shaft 3 is connected to the frame 6. The control module 5 is communicatively connected to the first drive module 9, the second drive module 4, and the auxiliary module 10, respectively, and is configured to receive collected information from the auxiliary module 10 and process the collected information to generate control instructions for the first drive module 9 and the second drive module 4.

[0048] The control module 5 includes an STM32 single-chip microcomputer, sensors, and other control components to control the shape of each bistable structure 3 and the start, stop, and travel speed of the wheel-leg conversion mechanism of this embodiment. The control module 5 can detect the deformation of the hinge 7 caused by the power supply of the first drive module 9 (e.g., a resistor) and control the Joule heat generated by the first drive module 9 to achieve morphological control of the wheel-leg conversion mechanism. Specifically, when the hinge 7 bends under the positive action of the first drive module 9, causing the angle between the spoke connected to the hinge 7 and the pseudo-rigid rod 8 to exceed the critical deformation angle, the bistable structure 3 transforms from a wheel shape to a leg shape. When the first drive module 9 stops functioning, the hinge 7 returns to its original shape, causing the angle between the spoke connected to the hinge 7 and the pseudo-rigid rod 8 to fall below the critical deformation angle, and the bistable structure 3 returns from a leg shape to a wheel shape.

[0049] The 12-segment, low-stiffness hinge 7 utilizes a shape memory polymer (SMP), preferably a polycarbonate-based shape memory polyurethane (PCPU), capable of controlled bending deformation or relative rotation of its ends. This SMP undergoes shape transformations by varying the ambient temperature. The low-stiffness hinge 7 is capable of multiple bends, and by varying the SMP's composition, the mechanism can achieve varying mechanical properties. The eight high-stiffness pseudo-rigid rods 8, designed for energy storage and release, utilize a relatively high-stiffness material, polypropylene (PP). Their stiffness exceeds that of the hinge 7 and is compatible with the PCPU's actuation capabilities. During wheel-leg transitions, the energy storage and release caused by their own deformation contribute to the structure's bistable nature.

[0050] The stiffness of the hinge 7 is lower than that of the pseudo-rigid rod 8. The hinge 7 determines the reversible deformation of the wheel-leg conversion mechanism. The pseudo-rigid rod determines that the reversible deformation of the wheel-leg conversion mechanism has a bistable characteristic, which can ensure that the bistable structure 3 of this embodiment is bistable.

[0051] The bistable structure 3 of this embodiment is a kind of flexible structure. It takes advantage of the fact that when the rod recovers to its original shape after deformation, the recovery speed is relatively fast, so that the stable state switching is completed quickly. Therefore, when the bistable structure 3 changes from a wheel shape to a leg shape, the high-rigidity pseudo-rigid rod 8 of this embodiment will go through a deformation-recovery stage, completing the energy storage-energy release process. That is, potential energy will be stored during deformation and released when it returns to its original shape. Figure 8 As shown, Figure 8 This embodiment reflects the energy storage and release process of the high-rigidity pseudo-rigid rod 8 during the deformation of the bistable structure 3.

[0052] In one specific embodiment of this embodiment, hinge 7 includes a first hinge 71 and a second hinge 72. The two ends of the second hinge 72 are each connected to one end of a pseudo-rigid rod 8. The other end of the pseudo-rigid rod 8 is connected to one end of the first hinge 71. The other end of the first hinge 71 is connected to the end of the spoke. The first hinge 71 and the second hinge 72 deform and bend in opposite directions. When deformed, the first hinge 71 becomes outwardly convex, while when deformed, the second hinge 72 becomes inwardly convex.

[0053] In a specific implementation of this embodiment, the first driving module 9 is a resistance wire, which is passed through the hinge 7 and the pseudo-rigid rod 8 (it can also be passed through only the hinge 7. When passed through the pseudo-rigid rod 8, the Joule heat generated by the power supply will not cause the deformation of the pseudo-rigid body 8). When the resistance wire is energized and heated, the first hinge 71 close to the spoke will undergo convex deformation due to the temperature reaching above the glass transition temperature, and the second hinge 72 located between the two pseudo-rigid rods 8 will undergo concave deformation due to the temperature reaching above the glass transition temperature. The wheel-leg conversion mechanism of this embodiment changes from a wheel shape to a leg shape due to the deformation of the hinge 7; conversely, when the power is cut off, the Joule heat stops being generated and the temperature drops. When the temperature is lower than the glass transition temperature, the first hinge 71 and the second hinge 72 begin to bend in the opposite direction to when the wheel shape changes to a leg shape, and slowly return to their original wheel shape at room temperature.

[0054] In one embodiment of this invention, the bistable structure 3 is integrally formed or 3D-printed, or hinged 7 is adhesively bonded to the pseudo-rigid rod 8 and the spokes. The bistable structure 3 as a whole does not require numerous kinematic pairs and components, resulting in a simpler structure and less assembly difficulty than other wheel-leg conversion mechanisms. To achieve single-degree-of-freedom or low-degree-of-freedom centralized drive, the first drive module 9 between the two spokes is integrally formed, i.e., it is also embedded within the pseudo-rigid rod 8.

[0055] In this embodiment, a specific implementation method is as follows: Figure 4 As shown, the bistable structure 3 has four spokes. The bistable structure 3 between two adjacent spokes can independently complete two actions: stretching into a wheel shape and contracting into a leg shape, with a total of six deformation states, such as Figure 4 a to Figure 4 As shown in Figure f, it is divided into four sectors with a sector angle of 90 degrees. The wheel leg conversion of each sector is individually controlled and combined. Specifically, the temperature is controlled by turning on / off the resistance wire in the sector to make the shape memory polymer bend in a directional manner. Figure 4 The six deformations shown can also be achieved by controlling the temperature difference.

[0056] During the leg-turning transformation process, when the bending moment provided by the low-rigidity hinge 7 reaches the critical value of the stable switching of the bistable structure 3, the bistable structure 3 can reversibly switch between the two stable states. The principle is as follows: Figure 3 Specifically, when the bistable structure 3 is in the wheel shape, the first drive module 9 is energized, causing the first hinge 71 to bend outwardly and convexly, while the second hinge 72 to bend inwardly and convexly, causing the bistable structure 3 to contract inward and transform into a leg shape. When the bistable structure 3 is in the leg shape, the outward convex deformation of the first hinge 71 decreases when the power is turned off, while the inward convex deformation of the second hinge 72 decreases, causing the bistable structure 3 to deform radially outward and transform into a wheel shape.

[0057] Since the stiffness of the polypropylene pseudo-rigid rod is constant in the entire bistable structure 3, the steady-state stiffness of the bistable structure 3 of this embodiment is mainly related to the stiffness of the shape memory polymer. Since the stiffness of the shape memory polymer itself shows regular changes with temperature, this characteristic can be used to adjust the steady-state stiffness according to actual needs, that is, through customized programming of permanent and temporary shapes, better structural performance can be obtained.

[0058] The bistable structure 3 will produce two different mechanical ranges of positive stiffness and negative stiffness when switching between stable states, such as Figure 7As shown. Under the bending moment load provided by the low-stiffness hinge 7, the wheel-leg conversion mechanism of this embodiment can switch between stable states and reversibly adjust its shape; the bistable structure 3 exhibits an N-shaped moment-displacement response curve under torque control conditions (the displacement here refers to the radial displacement of the second hinge 72 as a whole toward the center of the spoke). There are two positive stiffness stages during the loading process, namely the process from point O1 to point A and the process from point B to point C, and a negative stiffness stage from point A to point B; between the two stages of positive stiffness, there are two stable states, namely the points marked "O1" and "O2"; starting from these stable states, two different load-displacement paths emerge; when the bistable structure 3 is in a wheel shape, it enters a negative stiffness stage (from point O1 through point A to point B) when the critical load is reached through torque loading; and when the bistable structure 3 is in a leg shape, it exhibits a continuous increase in load (from point B directly to point C). In addition, Figure 8 The strain energy-displacement curve under moment load is shown. When the second hinge 72 bends inward (i.e., the second hinge 72 as a whole moves radially toward the center of the spoke), the strain energy of the entire bistable structure 3 shows a trend of first increasing and then decreasing. There are two minimum values ​​of strain energy, which are respectively at the initial stage and the final stage of displacement. That is, the bistable structure 3 of this embodiment has two stable states: wheel-shaped and leg-shaped.

[0059] When the bistable structure 3 encounters an obstacle, the obstacle will generate a radial inward force load on the bistable structure 3. Under the action of this load, the bistable structure 3 can passively complete the switch from wheel shape to leg shape. Its mechanical process is similar to the loading curve under displacement control conditions, such as Figure 8 As shown, displacement, as described above, refers to the radial displacement of the second hinge 72 as a whole toward the center of the spoke. The driving force required to deform the bistable structure 3 increases rapidly with increasing displacement. Once it reaches its numerical extreme, the bistable structure 3 jumps to the second-order buckling mode. The required driving force then decreases with increasing displacement until the buckled beam again jumps to the second stable position, achieving a transition between the wheel-shaped and leg-shaped stable states, again exhibiting the characteristics of bistability. By generating different torques, the bistable structure 3 undergoes different deformation stages, producing different feedback effects. These deformation behaviors and feedback effects impart distinct physical properties to the bistable structure 3. Joule heating generated by the electric drive significantly influences the structural stiffness and torque-displacement response curve. Users can influence Joule heating by adjusting parameters such as current, thereby regulating the mechanical loading characteristics of the bistable structure 3.

[0060] Therefore, the flexible deformation capability of the bistable structure 3 and the rapid switching of positive and negative stiffness can be used to achieve rapid switching of radial steady state. According to actual needs, the structural stiffness can be regulated and other characteristics of the mechanism can be improved through multi-objective optimization. Figure 10 As shown in FIG. 1 , by reducing the length of the low-rigidity hinge 7 and selecting a material with greater rigidity, the energy barrier of the stable transition can be increased, so that the stability of the bistable structure 3 is greatly enhanced, and a stable-enhanced type is obtained. However, the stress it is subjected to will also increase, and the service life of the stable structure 3 will be reduced accordingly. On the contrary, if Figure 10 As shown in Figure b, by increasing the length of the low-rigidity hinge 7 and selecting a material with lower rigidity, the stress on it can be reduced, significantly extending the service life of the structure and achieving a life-enhanced structure. The energy barrier to the structure's steady-state transition is also reduced, correspondingly lowering the structural stability. Reasonable structural optimization can enhance its ability to cope with complex environments.

[0061] In addition to PCPU and PP, other low and high stiffness materials of the bistable structure 3 can be selected according to the actual stiffness requirements. The feasibility of the scheme is demonstrated by combining simulation and experimental verification. The selection process of structural materials is as follows: Figure 11 As shown in the figure. First, a bistable structure is designed according to the theoretical method of the pseudo-rigid body model based on the design requirements. Then, three-dimensional modeling is performed and material properties that are expected to achieve the requirements are preliminarily assigned. The torque-displacement curve is obtained through finite element analysis simulation to verify the existence of bistable characteristics. Specifically, the Newton-Raphson algorithm, arc length method and other solution methods can be combined. Based on the simulation results, in the presence of bistable characteristics, the experimental material that is most likely to achieve the design requirements is selected, and the feasibility of the material is verified through experiments. Finally, the degree of overlap between the experimental results and the simulation is compared, and the solution with better overlap is selected as the design result.

[0062] In a specific implementation of this embodiment, the material of the hinge 7 can also be liquid crystal elastomer.

[0063] Example 2

[0064] The difference between Example 2 and Example 1 is that the hinge 7 in the bistable structure 3 of Example 2 is realized as a pneumatic structure, and the first driving module 9 is realized in the form of an air duct. Figure 12 As shown in a, the state switching principle is the same as that of embodiment 1.

[0065] The pneumatic structure of the hinge 7 can be made of commonly used materials for airbags such as silicone and rubber. The first drive module 9 includes an air duct and an air pump. The air pump is communicated with the control module 5. The air duct can be made of pressure-resistant materials such as polyurethane and polyethylene, and has good softness and repeatable bending properties.

[0066] When the hinge 7 is inflated, it can be bent in a directional manner. By deflating the hinge 7, the interior can be restored to the initial air pressure, so that the hinge 7 can return to its original shape.

[0067] When the bistable structure 3 is in a wheel shape, the control module 5 controls the air pump to inflate the first hinge 71 and the second hinge 72 of the pneumatic structure along the air duct, so as to realize the outward convex bending deformation of the first hinge 71 and the inward convex bending deformation of the second hinge 72. The wheel-leg conversion mechanism of this embodiment changes from a wheel shape to a leg shape due to the deformation of the hinge 7; when the bistable structure 3 is in a leg shape, the control module 5 controls the air pump to deflate the first hinge 71 and the second hinge 72 of the pneumatic structure along the air duct, and the first hinge 71 and the second hinge 72 begin to bend in the opposite direction to when the wheel shape changes to the leg shape, so that the bistable structure 3 returns to its initial wheel shape. The deformation principle of the bistable structure 3 of Example 2 is as follows: Figure 12 As shown in b, the reversible deformation of the wheel-leg conversion mechanism is also determined by the deformation of the pseudo-rigid rod 8 and has a bistable characteristic.

[0068] Example 3

[0069] The difference between Example 3 and Example 1 is that: Figure 13 As shown in a, the bistable structure 3 of embodiment 3 has only one first hinge 71, which is a pulley ( Figure 13 a, reference numeral 92); the second hinge 72 is implemented in the form of a flexible hinge; the length of the two pseudo-rigid rods 8 is also different from that in Example 1. The two pseudo-rigid rods 8 in this embodiment are one long and one short, namely the first pseudo-rigid rod 81 and the second pseudo-rigid rod 82. The length of the second pseudo-rigid rod 82 is greater than that of the first pseudo-rigid rod 81. In this embodiment, the hinge between the second pseudo-rigid rod 82 and the spoke is a passive hinge, which is passively deformed when the wheel legs are switched.

[0070] In a specific implementation of this embodiment, the second hinge 72 can be integrally formed with the pseudo rigid rod 8 , or manufactured separately and then bonded to the first pseudo rigid rod 81 and the second pseudo rigid rod 82 .

[0071] In a specific implementation of this embodiment, the bistable structure 3 in this embodiment can be an asymmetric structure, and the first hinge 71 between two adjacent spokes (at Figure 13 There is only one pulley 92 in a. The specific structure is: one end of the first pseudo-rigid rod 81 is connected to the first hinge 71 (in Figure 13The first drive module 9 includes a motor and a rope 91 that can output rotational motion. The rotational motion of the motor is transmitted to each pulley 92 by the rope 91, thereby driving the first pseudo-rigid rod 81 to swing around the pulley axis. The motor is in communication with the control module 5. The bistable structure 3 of this embodiment is as shown in FIG. Figure 13 As shown in a, the state switching principle is similar to that of Example 1. The pulley 92 rotates under the positive action of the first driving module 9, and the pulley 92 drives the first pseudo-rigid rod 81 to move. When the angle between the first pseudo-rigid rod 81 and the spoke with the pulley 92 connected to the end increases to the critical deformation angle, the bistable structure 3 is converted from a wheel shape to a leg shape; when the first driving module 9 acts in the reverse direction, the angle between the first pseudo-rigid rod 81 and the spoke with the pulley 92 connected to the end is reduced to below the critical deformation angle, and the bistable structure 3 is restored from a leg shape to a wheel shape.

[0072] Second hinge 72 is made of a low-rigidity material or structure, such as silicone, allowing for multiple bends. By using materials or structures with varying rigidity, the wheel-leg conversion mechanism of the present invention can exhibit varying mechanical properties. Pseudo-rigid rod 8 is made of a relatively rigid material, such as polypropylene or metal, and the rigidity of second hinge 72 is lower than that of pseudo-rigid rod 8.

[0073] When the bistable structure 3 is in the wheel shape, the rope 91 and the pulley 92 rotate the first pseudo-rigid rod 81 clockwise under the control of the motor. The wheel-leg conversion mechanism of this embodiment changes from a wheel shape to a leg shape due to the rotation of the first pseudo-rigid rod 81. When the bistable structure 3 is in the leg shape, the rope 91 and the pulley 92 rotate the first pseudo-rigid rod 81 counterclockwise under the control of the motor. The bistable structure 3 returns to its initial wheel shape. The deformation principle of the bistable structure 3 of Example 3 is as follows: Figure 13 As shown in b, the reversible deformation of the wheel-leg conversion mechanism is also determined by the deformation of the pseudo-rigid rod 8 and has a bistable characteristic.

[0074] In a specific implementation of this embodiment, the rope 91 and the pulley 92 can also be replaced by transmission devices such as chains and sprockets, belts and pulleys.

[0075] Example 4

[0076] The difference between Example 4 and Example 1, 2 or 3 is that the number of spokes in the bistable structure 3 of Example 4 is different from that of Example 1, 2 or 3.

[0077] The bistable structure 3 can be expanded to form a multi-leg structure. The number of legs can be customized according to user needs, and within a suitable scale, the bistable characteristics will not be affected. Since each bistable structure 3 has a stable characteristic, the deformation stability of the wheel leg is high. Figure 14 and Figure 15 As shown, the bistable structure 3 has three spokes. The bistable structure 3 between two adjacent spokes can independently complete two actions: stretching into a wheel shape and contracting into a leg shape, with a total of four deformation states, such as Figure 15 a to Figure 15 As shown in d.

[0078] In summary, the present invention provides a hinge-driven, bistable wheel-leg conversion mechanism. By driving hinge 7 to cause relative rotation between two adjacent components, the wheel-leg conversion mechanism switches between two stable states, achieving overall deformation.

[0079] Furthermore, the wheel-leg conversion mechanism of the present invention can achieve active deformation under user control. Leveraging the advantages of the bistable structure 3, it can meet multiple requirements, including flexible deformation, rapid switching between positive and negative stiffness, and controllable stiffness. By applying the wheel-leg conversion mechanism of the present invention to mobile machines (such as carts and mobile robots), it can solve problems such as cumbersome mode switching and complex control, achieving high adaptability to diverse terrains. This research has great value and significance in today's rapidly developing robotics technology.

[0080] The wheel-leg conversion mechanism of the present invention is driven by hinge 7 and can actively convert between wheel and leg forms by controlling the bending deformation of the material (hinge 7 and pseudo-rigidity rod 8). Actively converting between wheel and leg forms involves the first drive module 9 stimulating hinge 7 to bend or rotate according to instructions from control module 5, so that the angle between the hinged spokes and the pseudo-rigidity rod reaches above the critical deformation angle, at which point the bistable structure converts from wheel to leg form. When the first drive module stops or reverses its action, the angle between the hinged spokes and the pseudo-rigidity rod decreases. When the angle decreases below the critical deformation angle, the bistable structure returns from leg form to wheel form.

[0081] It should be noted that, in this application, relational terms such as first and second, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article, or device. In the absence of further restrictions, an element defined by the statement "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0082] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A hinge-driven bistable wheel-leg conversion mechanism, characterized by: The invention relates to a bistable structure having two stable states, a wheel shape and a leg shape. The bistable structure comprises a frame and a first driving module. The frame comprises a plurality of spokes distributed in an array. A hinge and a pseudo-rigid rod are provided between the ends of two adjacent spokes. The hinge is connected to the first driving module. The hinge is bent and deformed under the positive action of the first driving module. When the angle between the spoke connected to the hinge and the pseudo-rigid rod reaches a critical deformation angle, the bistable structure is converted from a wheel shape to a leg shape. When the first driving module stops acting, the hinge returns to its original state. When the angle between the spoke connected to the hinge and the pseudo-rigid rod reaches a critical deformation angle, the bistable structure is converted from a leg shape to a wheel shape. The stiffness of the pseudo-rigid rod is greater than the stiffness of the hinge. The hinge includes a first hinge and a second hinge, wherein both ends of the second hinge are respectively connected to one end of a pseudo-rigid rod, the other end of the pseudo-rigid rod is respectively connected to one end of the first hinge, and the other end of the first hinge is connected to the end of the spoke; The first hinge and the second hinge have opposite bending directions. The first hinge is convex when deformed, and the second hinge is convex when deformed.

2. The hinge-driven bistable wheel-leg conversion mechanism according to claim 1, characterized in that: It also includes a body, a rotating shaft, a second drive module for driving the start and stop and driving speed of the wheel-leg conversion mechanism, a control module for controlling the shape of the bistable structure, and an auxiliary module for exploring the external environment and feeding back the exploration results to the control module; the rotating shaft is connected to the frame of the bistable structure; the second drive module is connected to the rotating shaft, and is used to drive the rotating shaft to rotate, thereby driving the entire bistable structure to rotate; the control module is respectively communicated with the first drive module, the second drive module and the auxiliary module, and is used to receive the collected information sent by the auxiliary module, and send control instructions to the first drive module and the second drive module.

3. The hinge-driven bistable wheel-leg conversion mechanism according to claim 1, characterized in that: The first driving module is a resistance wire, the material of the hinge is polycarbonate shape memory polyurethane or liquid crystal elastomer; the material of the pseudo-rigid rod is polypropylene.

4. The hinge-driven bistable wheel-leg conversion mechanism according to claim 1, characterized in that: The first driving module includes an air pump and an air duct connected to each other. The air duct is connected to a hinge, and the hinge is a silicone pneumatic structure. The pseudo-rigid rod is made of polypropylene.

5. A hinge-driven bistable wheel-leg conversion mechanism, characterized in that: The invention relates to a bistable structure having two stable states, a wheel shape and a leg shape, wherein the bistable structure comprises a frame and a first driving module; the frame comprises a plurality of spokes distributed in an array, a hinge and a pseudo-rigid rod are provided between the ends of two adjacent spokes, the hinge comprises a first hinge and a second hinge, and the pseudo-rigid rod comprises a first pseudo-rigid rod and a second pseudo-rigid rod; the first hinge is provided at the end of the spoke, one end of the first pseudo-rigid rod is fixedly connected to the first hinge, the other end is connected to one end of the second hinge, and the other end of the second hinge is connected to the second pseudo-rigid rod One end of the rod is connected, and the other end of the second pseudo-rigid rod is directly hinged to the adjacent spoke; the first hinge is connected to the first driving module; the first hinge rotates under the positive action of the first driving module, and when the angle between the first pseudo-rigid rod and the spoke with the first hinge connected to the end increases to a critical deformation angle, the bistable structure is converted from a wheel shape to a leg shape; when the first driving module is reversed, the angle between the first pseudo-rigid rod and the spoke with the first hinge connected to the end decreases below the critical deformation angle, and the bistable structure recovers from a leg shape to a wheel shape.

6. The hinge-driven bistable wheel-leg conversion mechanism according to claim 5, characterized in that: The length of the second pseudo rigid rod is greater than that of the first pseudo rigid rod.

7. The hinge-driven bistable wheel-leg conversion mechanism according to claim 5, characterized in that: It also includes a body, a rotating shaft, a second drive module for driving the start and stop and driving speed of the wheel-leg conversion mechanism, a control module for controlling the shape of the bistable structure, and an auxiliary module for exploring the external environment and feeding back the exploration results to the control module; the rotating shaft is connected to the frame of the bistable structure; the second drive module is connected to the rotating shaft, and is used to drive the rotating shaft to rotate, thereby driving the entire bistable structure to rotate; the control module is respectively communicated with the first drive module, the second drive module and the auxiliary module, and is used to receive the collected information sent by the auxiliary module, and send control instructions to the first drive module and the second drive module.

8. The hinge-driven bistable wheel-leg conversion mechanism according to claim 7, characterized in that: The first hinge is a pulley, the first driving module includes a motor and a rope, the motor drives the pulley to rotate through the rope, and the motor is connected to the control module.

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