Hinge-driven bistable wheel-leg switching mechanism

Abstract

The invention relates to the technical field of robot compliant moving system design, and discloses a hinge-driven bistable wheel-leg switching mechanism which comprises a bistable structure with a wheel-shaped steady state and a leg-shaped steady state, the bistable structure comprises a rack and a first driving module, the rack comprises a plurality of spokes distributed in an array mode, and the first driving module comprises a first driving module and a second driving module. A hinge and a pseudo-rigid rod are arranged between the end parts of two adjacent spokes, and the hinge is connected with the first driving module; the hinge is bent and deformed under the forward action of the first driving module, the bistable structure is converted into a leg shape from a wheel shape, and when the first driving module stops acting, the hinge recovers to the original shape, and the bistable structure recovers to the wheel shape from the leg shape; and the rigidity of the pseudo-rigid rod is greater than that of the hinge. According to the invention, flexible deformation can occur when encountering an obstacle, so that the device adapts to various unstructured terrain environments, and has better buffering and energy-absorbing 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 high-tech such as mechanical electronics, control science, material technology and artificial intelligence, robotics technology, as a cross-disciplinary product, has made unprecedented progress and has been widely used. It has gradually transformed from initial theoretical research to product practice. As an important part of robotics technology, mobile robots play an indispensable role. They play a vital role in the exploration and reconnaissance of unknown terrain. Compared with letting humans perform tasks such as terrain exploration, deep space exploration and battlefield reconnaissance, mobile robots can not only reduce danger, but also save costs significantly.

[0003] Traditional mobile robots with a single motion mode have certain limitations when facing complex terrain and obstacles. These traditional robots lack the ability to adapt to diverse environments and overcome obstacles, resulting in reduced efficiency when encountering unstructured ground conditions during missions, which in turn affects the ability of mobile robots to complete tasks. In recent years, wheel-leg transformation robots have been widely studied because of their excellent working performance. In response to different working environments and performance requirements, people have designed a variety of different forms of robot mechanisms, such as structures suitable for flat land, deserts or extraterrestrial environments, with high load-bearing capacity or strong flexibility. There are also many robots with similar bistable structures that achieve wheel-leg transformation and jumping through the storage and release of elastic potential energy.

[0004] In addition, domestic research is currently mainly focused on achieving predetermined functions, while research on key technical points such as the combination optimization of multiple motion modes, the design theory of special-shaped wheels and deformed wheels, and the performance of a single motion mode needs to be further deepened. Moreover, there is currently little combination with bistable structures, and how to apply flexible design to wheel-leg conversion mechanisms has a high research significance. Summary of the invention

[0005] In view of the deficiencies of the prior art, the present invention provides a hinge-driven bistable wheel-leg conversion mechanism that can undergo flexible deformation when encountering obstacles, thereby adapting to a variety of 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, the hinge is connected to the first drive module; the hinge is bent and deformed 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 angle of deformation, the bistable structure is converted from a wheel shape to a leg shape, and when the first drive module stops acting, 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 angle of deformation, 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, 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.

[0009] In combination with the first aspect, further, the first hinge and the second hinge have opposite deformation and bending directions, the first hinge is convex when deformed, and the second hinge is convex when deformed.

[0010] In combination with the first aspect, further, the wheel-leg conversion mechanism of the present invention 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 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 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 driving module; the frame comprises a plurality of spokes distributed in an array, a hinge and a pseudo-rigid rod are arranged 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 arranged 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 a critical deformation angle, the bistable structure is converted from a wheel shape to a leg shape, and when the first drive module acts in the reverse direction, 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 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.

[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 compliant structure and 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 hinge-driven 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 that the configuration changes quickly 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 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 is a schematic diagram of the deformation principle of the bistable structure in Example 1 of the present invention;

[0027] Figure 4 Schematic diagrams 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 It is a schematic diagram of a three-dimensional mechanism of a compliant bistable wheel-leg conversion mechanism in Example 1 of the present invention;

[0029] Figure 6 1 is a bottom view structural diagram 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 moment loading in Example 1 of the present invention;

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

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

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

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

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

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

[0038] Fig.15 Schematic diagrams of four deformation modes of the bistable structure in Example 4 of the present invention, respectively Fig.15 a to Fig.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 be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work 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. The 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 reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0043] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply 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, including a vehicle body 1, a rotating shaft 3, a bistable structure 3 connected to the rotating shaft 3, a second driving 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 exploring the external environment and feeding back the exploration results to the control module 5. The auxiliary module 10 is arranged on the upper part of the vehicle body; the second driving module 4 and the control module 5 are respectively arranged on the lower part of the vehicle body 1; and a bistable structure 3 is connected to each end of the rotating shaft 3. The second driving 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, for exploring and providing feedback on the external environment, and transmitting 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 wheel shape and leg shape, including a frame 6 with 4 spokes, 12 sections of low-rigidity hinges 7 for controlled bending deformation, 8 sections of high-rigidity pseudo-rigid rods 8 for energy storage and release, and a first driving module 9 inserted in the hinges 7 and the pseudo-rigid rods 8; the rotating shaft 3 is connected to the frame 6. The control module 5 is respectively connected to the first driving module 9, the second driving module 4 and the auxiliary module 10 for receiving the collected information sent by the auxiliary module 10, and processing the collected information to obtain control instructions to the first driving module 9 and the second driving module 4.

[0048] The control module 5 includes control components such as an STM32 single-chip microcomputer and sensors to control the shape of each bistable structure 3 and the start and stop and driving 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 first drive module 9 (such as a resistance wire) being energized, and by regulating the size of the Joule heat generated by the first drive module 9, the shape of the wheel-leg conversion mechanism deformation is regulated, specifically: when the hinge 7 is bent and deformed under the positive action of the first drive module 9, so that the angle between the spoke connected to the hinge 7 and the pseudo-rigid body rod 8 reaches above the critical angle of deformation, the bistable structure 3 is converted from a wheel shape to a leg shape; when the first drive module 9 stops acting, the hinge 7 returns to its original state, so that the angle between the spoke connected to the hinge 7 and the pseudo-rigid body rod 8 reaches below the critical angle of deformation, and the bistable structure 3 is restored from a leg shape to a wheel shape.

[0049] The 12-segment low-rigidity hinge 7 uses a material, structure or component shape memory polymer (SMP) that can be controlled to achieve bending deformation or relative rotation at both ends. Polycarbonate shape memory polyurethane (PCPU) is preferably used. The SMP can undergo a shape change by changing the external temperature. The low-rigidity hinge 7 can be bent multiple times, and by changing the synthetic components of the SMP, the mechanism can have different mechanical properties. The 8-segment high-rigidity pseudo-rigid rod 8 for energy storage and release uses polypropylene (PP), a material with higher rigidity. The rigidity is higher than that of the hinge 7 and is adapted to the actuation ability of the PCPU. The energy storage and release caused by its own deformation during the wheel-leg conversion realize the bistable characteristics of the structure.

[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 compliant structure. When the rod member recovers to its original state after deformation, the recovery speed is fast, so as to quickly complete the stable state switching. 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 and complete the energy storage-energy release process, that is, potential energy will be stored during deformation and released when it returns to its original state. Figure 8 As shown, Figure 8 This shows the energy storage and release process of the high-rigidity pseudo-rigid rod 8 in the embodiment during the deformation of the bistable structure 3.

[0052] In a specific implementation of this embodiment, the hinge 7 includes a first hinge 71 and a second hinge 72, the two ends of the second hinge 72 are respectively 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, and 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 have opposite deformation and bending directions, the first hinge 71 is convex when deformed, and the second hinge 72 is convex when deformed.

[0053] In a specific implementation of the present embodiment, the first driving module 9 is a resistance wire, which is inserted into the hinge 7 and the pseudo-rigid rod 8 (it can also be inserted only into the hinge 7. When it is inserted into 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 the present embodiment changes from a wheel shape to a leg shape due to the deformation of the hinge 7; conversely, when the power is turned 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 initial wheel shape at room temperature.

[0054] In a specific implementation of this embodiment, the bistable structure 3 is integrally formed or 3D printed or the hinge 7 is fixedly connected to the pseudo rigid rod 8 and the spoke by gluing. The bistable structure 3 as a whole does not require too many kinematic pairs and parts. Compared with other forms of wheel-leg conversion mechanisms, it has a simple structure and is easy to assemble. In order to achieve single-degree-of-freedom or low-degree-of-freedom centralized drive, the first drive module 9 between the two spokes is a whole, that is, the first drive module 9 is also inserted into the pseudo rigid rod 8.

[0055] In a specific implementation of this embodiment, as Figure 4 As shown, the bistable structure 3 has four spokes, and the bistable structure 3 between two adjacent spokes can independently complete two actions of extending 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 f, it is divided into four sectors with a sector angle of 90°, and the shape memory polymer is directional-bent by controlling the wheel-leg conversion of each sector individually, specifically by turning on / off the resistance wire in the sector, thereby controlling the temperature. Figure 4 The six deformations shown can also be achieved by controlling the temperature differences.

[0056] During the transformation process of the rotating leg, when the bending moment provided by the low-rigidity hinge 7 reaches the critical value of the stable state 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 driving module 9 is powered on, the first hinge 71 is deformed to be convex outward, and the second hinge 72 is deformed to be convex inward, causing the bistable structure 3 to shrink inward and transform into a leg shape; when the bistable structure 3 is in the leg shape, the convex bending deformation of the first hinge 71 is reduced under the action of power failure, and the convex bending deformation of the second hinge 72 is reduced, 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 certain 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 will show regular changes with temperature changes, this characteristic can be used to adjust the steady-state stiffness according to actual needs, that is, through customized programming of permanent shape and temporary shape, 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-rigidity hinge 7, the wheel-leg conversion mechanism of this embodiment can switch between stable states and can reversibly adjust its shape; the bistable structure 3 shows an N-shaped moment-displacement response curve under the torque control condition (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 in 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 as "O1" and "O2"; starting from these stable states, two different load-displacement paths appear; when the state of the bistable structure 3 is wheel-shaped, it enters the negative stiffness stage (from point O1 through point A to point B) when the critical load is reached through moment loading; and when the state of the bistable structure 3 is leg-shaped, it shows a continuous increase in load (from point B directly to point C). In addition, Figure 8 The strain energy-displacement curve under the moment load is shown. When the second hinge 72 bends inward (that is, the second hinge 72 moves radially toward the center of the spoke as a whole), the strain energy of the entire bistable structure 3 shows a trend of first increasing and then decreasing. There are two minimum values ​​of the strain energy, which are respectively in the initial stage and the final stage of the displacement. That is, the bistable structure 3 of this embodiment has two stable states, namely, the wheel shape and the leg shape.

[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 the wheel shape to the leg shape, and its mechanical process is similar to the loading curve under the displacement control condition, such as Figure 8 As shown, the displacement refers to the radial displacement of the second hinge 72 as a whole toward the center of the spoke as described above. The driving force required for the deformation of the bistable structure 3 increases rapidly with the increase of the displacement. When the numerical extreme value is reached, the bistable structure 3 jumps to the second-order buckling mode, and then the required driving force decreases with the increase of the displacement until the buckled beam jumps to the second stable position again, realizing the transition between the wheel-shaped and leg-shaped stable states, and also showing the characteristics of the bistable state. By generating different torques, the bistable structure 3 undergoes different deformation stages and produces different feedback effects. These deformation behaviors and feedback effects bring different physical properties to the bistable structure 3. The Joule heat generated by the electric drive has a great influence on the structural stiffness and the torque-displacement response curve. The user can affect the Joule heat by adjusting parameters such as the current, and then regulate the mechanical loading characteristics of the bistable structure 3.

[0060] Therefore, the flexible deformation ability 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. Fig.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 steady-state transition can be increased, so that the stability of the bistable structure 3 is greatly enhanced, and a steady-state enhanced type is obtained. 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 Fig.10 As shown in FIG. 2 , by increasing the length of the low-rigidity hinge 7 and selecting a material with lower rigidity, the stress on it can be reduced, so that the service life of the structure is greatly extended, and a life-enhanced type is obtained. The energy barrier of the steady-state transition of the structure will also be reduced, and the steady state of the structure will be reduced accordingly. Reasonable optimization of the structure can improve 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: Fig.11 As shown. First, according to the design requirements, the bistable structure is designed according to the theoretical method of the pseudo-rigid body model. Then, three-dimensional modeling is performed and the 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 the bistable characteristics. Specifically, the Newton-Raphson algorithm, arc length method and other solution methods can be combined. According to 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 coincidence between the experimental results and the simulation is compared, and the scheme with better coincidence is selected as the design result.

[0062] In a specific implementation of this embodiment, the material of the hinge 7 may 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 by a pneumatic structure, and the first driving module 9 is realized in the form of an air guide tube. Fig.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 airbag materials such as silicone and rubber. The first drive module 9 includes an air duct and an air pump. The air pump is communicatively connected to 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 state of the bistable structure 3 is 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 state of the bistable structure 3 is 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: Fig.12 b. Similarly, the reversible deformation of the wheel-leg conversion mechanism is 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: Fig.13 As shown in a, in the bistable structure 3 of embodiment 3, there is only one first hinge 71, which is a pulley ( Fig.13 a, marked as 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 leg is switched.

[0070] In a specific implementation of the present embodiment, the second hinge 72 can be integrally formed with the pseudo rigid rod 8 , or can be 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 (in Fig.13 a is a pulley 92). The specific structure is: one end of the first pseudo-rigid rod 81 is connected to the first hinge 71 (in Fig.13a is a pulley 92) fixedly connected, and the other end is connected to one end of the second hinge 72; the pulley 92 is set at the end of a spoke; the other end of the second hinge 72 is connected to one end of the second pseudo-rigid rod 82, and the other end of the second pseudo-rigid rod 82 is directly hinged to the frame 6. The 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 connected to the control module 5 for communication. The bistable structure 3 of this embodiment is as shown in FIG. Fig.13 As shown in a, the switching principle of its state 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 angle of deformation, 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 angle of deformation, and the bistable structure 3 is restored from a leg shape to a wheel shape.

[0072] The second hinge 72 is made of low-rigidity materials or structures such as silicone and can be bent multiple times. By using materials or structures with different rigidity, the wheel-leg conversion mechanism of the present invention can have different mechanical properties. The pseudo-rigid rod 8 is made of materials such as polypropylene or metal with higher rigidity, and the rigidity of the second hinge 72 is lower than that of the pseudo-rigid rod 8.

[0073] When the state of the bistable structure 3 is a wheel shape, the rope 91 and the pulley 92 rotate the first pseudo-rigid rod 81 clockwise under the control of the motor, and 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 state of the bistable structure 3 is a leg shape, the rope 91 and the pulley 92 rotate the first pseudo-rigid rod 81 counterclockwise under the control of the motor, and the bistable structure 3 returns to its initial wheel shape. The deformation principle of the bistable structure 3 of Example 3 is as follows: Fig.13 b. Similarly, the reversible deformation of the wheel-leg conversion mechanism is 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 extended 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 are not affected. Since each bistable structure 3 has a stable characteristic, the deformation stability of the wheel leg is high. Fig.14 and Fig.15 As shown, the bistable structure 3 has three spokes, and the bistable structure 3 between two adjacent spokes can independently complete two actions: stretching into a wheel shape and contracting into a leg shape, for a total of four deformation states, such as Fig.15 a to Fig.15 As shown in d.

[0078] In summary, the present invention provides a hinge-driven bistable wheel-leg conversion mechanism. By driving the hinge 7 to make two adjacent components rotate relative to each other, the wheel-leg conversion mechanism of the present invention switches between the two stable states of wheel shape and leg shape to achieve overall deformation.

[0079] In addition, the wheel-leg conversion mechanism of the present invention can realize active deformation under user control, and with the advantage of the bistable structure 3, it can meet multiple requirements such as flexible deformation, rapid switching of positive and negative stiffness, and controllable stiffness. By applying the wheel-leg conversion mechanism of the present invention to a movable machine (such as a car, a mobile robot, etc.), the problems of cumbersome mode switching and complex control are solved, and high adaptability to different terrains is achieved, which has great research value and significance in today's increasingly developed robotics technology.

[0080] The wheel-leg conversion mechanism of the present invention is driven by the hinge 7, and can actively convert between the wheel shape and the leg shape by controlling the bending deformation of the material (the hinge 7 and the pseudo-rigidity rod 8). Actively converting between the wheel shape and the leg shape means that the first driving module 9 stimulates the hinge 7 to produce bending deformation or rotation according to the instruction of the control module 5, so that the angle between the hinge-connected spoke and the pseudo-rigidity rod reaches above the critical angle of deformation, and the bistable structure is converted from the wheel shape to the leg shape; when the first driving module stops acting or acts in the reverse direction, the angle between the hinge-connected spoke and the pseudo-rigidity rod is reduced, and when the angle is reduced to below the critical angle of deformation, the bistable structure is restored from the leg shape to the wheel shape.

[0081] It should be noted that, in this application, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including 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 equipment. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements.

[0082] Although 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 the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A hinge-driven bistable wheel-leg conversion mechanism, characterized in that: The invention comprises 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, wherein the frame comprises 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 driving module; the hinge is bent and deformed under the positive action of the first driving module, so that after the angle between the spoke connected to the hinge and the pseudo-rigid rod reaches above the critical angle of deformation, 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, so that after the angle between the spoke connected to the hinge and the pseudo-rigid rod reaches below the critical angle of deformation, 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.

2. A hinge-driven bistable wheel-leg conversion mechanism according to claim 1, characterized in that: The hinge includes a first hinge and a second hinge, wherein 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.

3. A hinge-driven bistable wheel-leg conversion mechanism according to claim 2, characterized in that: The first hinge and the second hinge are deformed and bent in opposite directions. The first hinge is convex when deformed, and the second hinge is convex when deformed.

4. 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 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 collection information sent by the auxiliary module, and send control instructions to the first drive module and the second drive module.

5. 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.

6. 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 material of the pseudo-rigid rod is polypropylene.

7. A hinge-driven bistable wheel-leg conversion mechanism, characterized in that: The invention comprises 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 arranged 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 arranged 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 second pseudo-rigid 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 the critical angle of deformation, the bistable structure is converted from a wheel shape to a leg shape, and 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 to below the critical angle of deformation, and the bistable structure recovers from a leg shape to a wheel shape.

8. The hinge-driven bistable wheel-leg conversion mechanism according to claim 7, characterized in that: The length of the second pseudo rigid rod is greater than that of the first pseudo rigid rod.

9. The hinge-driven bistable wheel-leg conversion mechanism according to claim 7, 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 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 collection information sent by the auxiliary module, and send control instructions to the first drive module and the second drive module.

10. The hinge-driven bistable wheel-leg conversion mechanism according to claim 9, 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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