A robot foot structure, leg assembly, and robot

Abstract

This invention discloses a robot foot structure, leg assembly, and robot, belonging to the field of robot technology. It includes a foot body, a shock-absorbing buffer layer, a connecting base plate, a buffer connector, and a bottom buffer layer. The connecting base plate connects the shock-absorbing buffer layer to the bottom of the foot body via the buffer connector. The connecting base plate can move vertically relative to the foot body under the action of the buffer connector. The bottom buffer layer is connected to the bottom of the connecting base plate and is used for direct contact with the contact surface. The bottom buffer layer provides initial cushioning while increasing friction with the contact surface. The shock-absorbing buffer layer provides secondary cushioning. This invention's robot foot structure, leg assembly, and robot can effectively solve the problems of existing robot foot structures failing to effectively mitigate the impact of instantaneous impact forces on the leg structure during walking and jumping landings, and the tendency to slip on uneven surfaces during walking.

Description

Technical Field

[0001] This invention belongs to the field of robotics technology. Specifically, it relates to a robot foot structure, leg assembly, and robot. Background Technology

[0002] The foot is a critical component that directly contacts the ground when a humanoid robot walks and jumps, directly affecting the overall stability and lifespan of the mechanism. Existing robot feet are mostly rigid or simple elastic structures, directly contacting the ground. During walking and jumping landings, they bear significant instantaneous impacts. These impact forces are directly transmitted to the leg joints, transmission mechanisms, and the overall structure above the foot. Prolonged exposure to these impacts can easily cause joint wear and component fatigue damage, reducing the robot's overall lifespan and operational reliability. Furthermore, when walking on uneven surfaces, robots are prone to slipping and falling. To mitigate the impact of these instantaneous impacts on the leg mechanism and address the slippage issue during walking, a robot foot structure with good cushioning and energy absorption capabilities and anti-slip functionality is urgently needed. Summary of the Invention

[0003] The purpose of this invention is to address the aforementioned shortcomings by providing a robot foot structure, leg assembly, and robot, thereby solving the problems of existing robot foot structures failing to effectively mitigate the impact of instantaneous impact forces on the leg structure during walking and jumping landings, and being prone to slipping on uneven surfaces. To achieve the above objective, this invention provides the following technical solution: A robot foot structure includes a foot body, a shock-absorbing buffer layer, a connecting base plate, a buffer connector, and a bottom buffer layer. The connecting base plate connects the shock-absorbing buffer layer to the bottom of the foot body via the buffer connector. The connecting base plate can move vertically relative to the foot body under the action of the buffer connector. The bottom buffer layer is connected to the bottom of the connecting base plate and is used to directly contact the contact surface. The bottom buffer layer is used to achieve initial cushioning while increasing the friction with the contact surface. The shock-absorbing buffer layer is used to achieve secondary cushioning.

[0004] Furthermore, the foot body includes a sole plate and an ankle connecting portion; the ankle connecting portion is vertically connected to the sole plate.

[0005] Furthermore, the buffer connector includes a plurality of guide posts and a locking member; the bottoms of the plurality of guide posts are fixedly connected to the connecting base plate at even intervals; the foot plate is provided with a plurality of first through holes; the shock-absorbing buffer layer is provided with a plurality of second through holes; the guide posts, the first through holes and the second through holes correspond one-to-one; the plurality of guide posts are installed on the foot plate after passing through the second through holes and the first through holes in sequence; the locking member can be fixedly connected to the upper end of the guide posts to prevent the connecting base plate and the shock-absorbing buffer layer from detaching from the foot plate.

[0006] Furthermore, the locking component includes a screw, a washer, and an oil-free bushing; the top of the guide post is provided with a threaded hole; the lower part of the oil-free bushing is fitted onto the guide post; the upper part of the oil-free bushing is larger than the diameter of the first through hole; the screw passes through the washer and engages with the threaded hole for a fixed connection, thereby fixing the locking component to the upper end of the guide post.

[0007] Furthermore, the shock-absorbing buffer layer is a non-Newtonian fluid material layer; the non-Newtonian fluid material layer can instantly harden and absorb energy when subjected to impact force.

[0008] Furthermore, the bottom buffer layer is a negative Poisson's ratio structure formed of a non-Newtonian fluid material, which can increase the frictional force between itself and the working surface while buffering and absorbing energy.

[0009] Furthermore, the shock-absorbing buffer layer includes at least two buffer layers; a rigid connection layer is provided between two adjacent buffer layers.

[0010] Furthermore, the buffer layer is a non-Newtonian fluid material layer.

[0011] A leg assembly comprising the aforementioned robotic foot structure.

[0012] A robot comprising the aforementioned leg assembly.

[0013] The beneficial effects of this invention are: The robot's foot in this application utilizes a shock-absorbing structure comprised of a shock-absorbing layer made of a non-Newtonian fluid material and a bottom buffer layer made of a negative Poisson's ratio non-Newtonian material. When the robot's leg contacts the ground, the bottom buffer layer, located at the bottommost layer, is the first to impact the ground and instantly hardens to absorb the impact energy. Then, the upper shock-absorbing layer buffers the deformation and participates in energy absorption. Compared to a single-layer buffer structure, this structure is softer and produces greater deformation under the same falling energy. The peak force and impact acceleration of the upper structure of the robot's foot from the ground are lower, significantly reducing the probability of damage to the upper structure of the robot's foot, improving the overall stability of the robot, and extending the robot's service life. Furthermore, by setting the bottom buffer layer to a negative Poisson's ratio structure made of a non-Newtonian fluid material, the friction between the robot and the ground is increased while absorbing energy, preventing the robot from slipping on uneven surfaces. Attached Figure Description

[0014] Figure 1 This is a top view of the foot body of the present invention; Figure 2 This is a cross-sectional view of the foot body of the present invention; Figure 3 This is a schematic diagram of the structure of an embodiment of the shock-absorbing buffer layer of the present invention; Figure 4 This is a partially enlarged schematic diagram of the negative Poisson's ratio structure of the bottom buffer layer of the present invention; Figure 5 This is a schematic diagram showing the deformation of the negative Poisson's ratio structure of the present invention under stress; Figure 6 This is a schematic diagram illustrating the principle of energy absorption in non-Newtonian fluids. Figure 7 This is a diagram illustrating the energy absorption principle of non-Newtonian fluid materials. In the attached diagram: 1. Foot body; 11. Foot sole; 12. Ankle connection; 2. Shock-absorbing buffer layer; 21. First buffer layer; 22. Second buffer layer; 23. Rigid connection layer; 3. Connecting base plate; 4. Bottom buffer layer; 5. Guide post; 6. Screw; 7. Washer; 8. Oil-free bushing. Detailed Implementation

[0015] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the present invention is not limited to the following embodiments.

[0016] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0017] In the description of this invention, "first feature" and "second feature" may include one or more of the features.

[0018] In the description of this invention, "a plurality of" means two or more.

[0019] In the description of this invention, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or it may include the first and second features not being in direct contact but being in contact through another feature between them.

[0020] In the description of this invention, the terms "above," "over," and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicating that the first feature is at a higher horizontal level than the second feature.

[0021] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," and "some examples" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0022] Example 1 See attached Figures 1-7This embodiment discloses a robot foot structure, including a foot body 1, a shock-absorbing buffer layer 2, a connecting base plate 3, a buffer connector, and a bottom buffer layer 4. The foot body 1 serves as the foundation support for the entire structure, connecting to the robot's leg structure. Specifically, the foot body 1 includes a sole plate 11 and an ankle connector 12. The sole plate 11 has a horizontal plate-like structure, with its lower surface being the main contact surface. The ankle connector 12 is vertically fixed to the upper surface of the sole plate 11 for connection to the robot's leg structure. The sole plate 11 and the ankle connector 12 can be manufactured using an integral molding or separate fixed connection method to ensure sufficient structural strength. For example, as... Figure 1 and Figure 2 As shown, the ankle connection 12 is fixedly installed on one side (width direction) of the foot plate 11.

[0023] The shock-absorbing buffer layer 2 is used to provide secondary cushioning for the robot's foot, and it is made of a non-Newtonian fluid material. It is configured as a sheet or plate that matches the footplate 11. In this embodiment, the shock-absorbing buffer layer 2 is preferably made of a non-Newtonian fluid material such as D3O, which can instantly harden and absorb energy upon impact.

[0024] The shock-absorbing buffer layer 2 is sandwiched between the foot plate 11 and the connecting base plate 3. The connecting base plate 3 is located between the shock-absorbing buffer layer 2 and the bottom buffer layer 4. The upper surface of the connecting base plate 3 contacts the lower surface of the shock-absorbing buffer layer 2, and the lower surface of the connecting base plate 3 is used to install the bottom buffer layer 4.

[0025] The cushioning connector includes several guide posts 5 and locking elements. The guide posts 5 are vertically fixed to the upper surface of the connecting base plate 3. The bottom end of each guide post 5 is fixed to the connecting base plate 3, and the top end extends upwards. Several first through holes are provided on the foot plate 11, and several second through holes are provided on the shock-absorbing buffer layer 2. The number and position of the first and second through holes correspond one-to-one with the guide posts 5 on the connecting base plate 3. Each guide post 5 on the connecting base plate 3 is aligned with and passed through the second through hole on the shock-absorbing buffer layer 2, and then continues upwards through the first through hole on the foot plate 11. The connecting base plate 3 is then mounted below the foot plate 11 via its guide posts 5. Because the guide posts 5 can slide freely up and down within the first and second through holes, the connecting base plate 3 can move within a certain range in the vertical direction relative to the foot plate 11, providing travel space for the cushioning action of the foot.

[0026] The locking element is used to prevent the connecting base plate 3 and the shock-absorbing buffer layer 2 from accidentally detaching from the foot plate 11. The locking element is located at the top of the guide post 5. In this embodiment, the locking element specifically includes a screw 6, a washer 7, and a flanged oil-free bushing 8. Correspondingly, a threaded hole for mating is vertically opened on the top end face of each guide post 5. The flanged oil-free bushing 8 is inserted from the top of the guide post 5, so that its lower part fits on the outer wall of the guide post 5. The top of the flanged oil-free bushing 8 has a flange with a diameter larger than the diameter of the first through hole on the foot plate 11. After installation, the flange can be locked at the upper edge of the first through hole. Then, the washer 7 is placed on the flange of the flanged oil-free bushing 8, and finally the screw 6 is passed through the washer 7 and screwed into the threaded hole at the top of the guide post 5 and tightened. The screw 6, the washer 7, and the flanged oil-free bushing 8 together form a limiting structure. When the connecting base plate 3 is subjected to downward tension, the flange with the oil-free flange bushing 8 will be stuck on the upper edge of the first through hole of the foot plate 11, thereby restricting the connecting base plate 3 and the shock-absorbing buffer layer 2 from continuing to move downward, ensuring that they will not come off from under the foot plate 11.

[0027] The bottom buffer layer 4 is the outermost component that directly contacts the ground (or other action surface) of the robot's foot. It is fixedly installed on the lower surface of the connecting base plate 3. The bottom buffer layer 4 has special structural and material properties. It also uses a non-Newtonian fluid material. Structurally, the bottom buffer layer 4 is fabricated as a negative Poisson's ratio structure. A negative Poisson's ratio structure is a material structure with a special geometric configuration. Conventional materials become thinner perpendicular to the stretching direction when stretched (positive Poisson's ratio), while a negative Poisson's ratio structure widens perpendicular to the stretching direction when stretched, and conversely, shrinks and gathers towards the point of impact when compressed. The bottom buffer layer 4 can be achieved through various manufacturing processes, such as direct molding using 3D printing technology, or by embedding a non-Newtonian fluid material into a porous or deformable matrix to construct a stable negative Poisson's ratio structure. Figure 5 As shown in Figure a, where Figure a represents the deformation that begins when the negative Poisson's ratio non-Newtonian fluid layer comes into contact with the ground protrusion; and Figure b represents the complete encapsulation of the ground protrusion by the negative Poisson's ratio non-Newtonian fluid layer. This special design allows the bottom buffer layer 4 to absorb energy when impacted by the ground, relying not only on the properties of non-Newtonian fluids but also on the deformation characteristics of the negative Poisson's ratio structure to better conform to the uneven ground, thereby significantly increasing the actual contact area and friction between the foot and the ground, effectively preventing slippage.

[0028] In a preferred embodiment, to further enhance the cushioning effect, the shock-absorbing buffer layer 2 is composed of at least two buffer layers and a rigid connecting layer 23 disposed between two adjacent buffer layers. Here, the at least two buffer layers can be respectively adhered to both sides of the rigid connecting layer 23, and the second through hole penetrates the rigid connecting layer 23 and the at least two buffer layers. For example, as... Figure 3 As shown, a first buffer layer 21, a rigid connecting layer 23, and a second buffer layer 22 can be configured. Both the first buffer layer 21 and the second buffer layer 22 are non-Newtonian fluid material layers, while the intermediate rigid connecting layer 23 is made of materials such as rigid plastic or thin metal sheets. The first buffer layer 21 and the second buffer layer 22 are fixed to the rigid connecting layer 23 with screws. Here, the height of the screws should be less than the thickness of the first buffer layer 21 and the second buffer layer 22, allowing the first buffer layer 21 and the second buffer layer 22 to be compressible. This multi-layer cascaded structural design can further reduce the overall equivalent stiffness of the entire shock absorption system, thereby achieving better buffering performance.

[0029] The energy absorption principle of non-Newtonian fluid materials: Non-Newtonian fluids are intelligent materials whose mechanical properties change with external forces. In this invention, both the shock-absorbing buffer layer 2 and the bottom buffer layer 4 rely on this property of non-Newtonian fluids.

[0030] When the robot's feet walk at a normal speed, the pressure changes applied to the non-Newtonian fluid layer are relatively gradual. At this time, the non-Newtonian fluid maintains its soft, flowable state and adapts well to the shape of the ground. However, when the robot lands from a certain height or jumps, a huge instantaneous impact velocity and force are generated between its feet and the ground. Under such high-speed impact, the viscosity of the non-Newtonian fluid increases exponentially. Its energy absorption mechanism can be divided into material energy absorption and buffer energy absorption.

[0031] Material energy absorption: According to the rheological principles of non-Newtonian fluids, the relationship between shear stress and velocity gradient can be described by the following formula: F / A = η*V / h; Where F / A is the shear stress (Pa), representing the frictional resistance between two adjacent fluid layers, which is related to the contact area; η is the viscosity coefficient (Pa·S), and the viscosity coefficient increases exponentially with increasing velocity in non-Newtonian fluids; V / h is the velocity gradient (S -1 This refers to the change in velocity per unit distance. When a foot strikes the ground at high speed, the non-Newtonian fluid layer is instantly compressed, causing a sharp increase in its internal velocity gradient V / h. This results in an exponential increase in the material's viscosity coefficient η, and the impact site instantly hardens. The impact kinetic energy is efficiently converted into heat energy through intense friction within the non-Newtonian fluid and the mutual compression and collision between solid particles, thus dissipating.

[0032] Buffering and energy absorption: During the hardening process of a non-Newtonian fluid layer, its effective buffering stroke can absorb impact kinetic energy. The impact kinetic energy is given by the classical formula: Where m is the impact mass and v is the impact velocity. The energy absorbed by the cushioning material can be calculated by integrating the instantaneous cushioning resistance (F(x)) over its compression stroke, i.e.: ; Simplifying the formula using average force: ; It can be seen that the average buffer force can be expressed as: ; Where F' is the average cushioning force and S is the effective cushioning stroke. This simplified formula clearly shows that, under the same impact energy E, the longer the cushioning stroke S, the smaller the average cushioning force F', and the lower the peak impact force transmitted to the structures above the foot.

[0033] This embodiment employs a layout consisting of two non-Newtonian fluid layers connected in series: a "bottom buffer layer 4" and a "shock-absorbing buffer layer 2". From a mechanical perspective, these two layers can be considered as two springs with different stiffnesses (k1 and k2, respectively). The upper shock-absorbing buffer layer 2 remains relatively soft, primarily responsible for buffering and absorbing energy; the lower bottom buffer layer 4 hardens upon contact with the ground, responsible for initial energy absorption and support. When the robot's foot structure lands, the lower bottom buffer layer 4 first hardens upon contact with the ground to absorb energy, and then the upper shock-absorbing buffer layer 2 first buffers deformation before participating in energy absorption.

[0034] Based on the physical principle of springs connected in series, the equivalent stiffness of the entire system after two springs are connected in series is expressed by the following formula: ; Among them, K eq Let S be the equivalent stiffness of the system. Because the system is connected in series, the overall equivalent stiffness is inevitably reduced and becomes less than the stiffness of the spring with the lowest stiffness in the system. Therefore, the entire system becomes softer, resulting in greater deformation, lower peak force, and lower impact acceleration for the same drop energy. During the actual landing, the bottom non-Newtonian fluid layer first contacts the ground. It hardens instantly upon impact, absorbing the first wave of impact energy. Subsequently, the impact energy is transmitted upwards, and the upper shock-absorbing buffer layer 2 begins to deform. Due to the low overall stiffness after series connection, the upper shock-absorbing buffer layer 2 can produce a relatively large compressive deformation. This larger deformation means that the impact energy can be released more smoothly. According to the above average buffer force formula, for the same drop energy, a larger total deformation (i.e., an increased effective buffer stroke S) significantly reduces the average impact force F' borne by the upper structure of the robot's foot.

[0035] In a preferred embodiment, the shock-absorbing buffer layer 2 is optimized to be a multi-layer structure comprising two buffer layers, namely a first buffer layer 21, a second buffer layer 22, and an intermediate rigid connecting layer 23, further enhancing the aforementioned series connection effect. This is equivalent to connecting three springs (bottom buffer layer 4, first buffer layer 21, and second buffer layer 22) in series. Considering the first buffer layer 21 and the second buffer layer 22 as springs, and assuming they have equal stiffness (k), the equivalent stiffness of the series springs is: ; but, ; That is, the equivalent stiffness becomes 1 / 2 of the original, and the entire buffer and shock absorption system becomes softer. Under the same falling energy, the system deformation is greater, the peak force is smaller, and the impact acceleration is lower. When the shock absorption buffer layer 2 contains two or more buffer layers (assuming N layers), its principle is similar to the buffer and shock absorption principle, except that the equivalent stiffness becomes 1 / N of the original.

[0036] In this embodiment, the non-Newtonian fluid of the bottom buffer layer 4 is set to a negative Poisson's ratio structure, so that the non-Newtonian fluid layer has impact resistance, energy absorption and shape conforming properties, can adapt to uneven ground, increase the friction between the robot's feet and the ground, and prevent the robot from slipping when walking on uneven ground.

[0037] Based on the negative Poisson's ratio structure, the material hardness H is related to the elastic modulus E and Poisson's ratio v as follows: ; This expression clearly shows that the material hardness H changes with the absolute value of Poisson's ratio v. The higher the material hardness H, the greater its resistance to indentation (i.e., indentation resistance). When the material has a negative Poisson's ratio, v is negative, and its square v² is positive, causing the denominator (1-v²) to decrease significantly, thus the material hardness H increases sharply. When the Poisson's ratio v approaches its theoretical minimum value of -1, the denominator (1-1) approaches zero, and the indentation resistance approaches infinity. This means that when the robot's foot touches the ground and generates an impact, the bottom buffer layer 4 of the negative Poisson's ratio structure will contract to conform to the ground, increasing the friction between the robot's foot and the ground, and preventing the robot from slipping when walking on uneven surfaces.

[0038] Example 2 This embodiment discloses a leg assembly, including the robot foot structure of Embodiment 1. The remaining parts of the leg assembly, such as the thigh, calf, knee joint, and ankle joint, can adopt any conventional design suitable for humanoid robots in the art and be adapted and connected to the ankle connection portion 12 of the robot foot structure of this embodiment. By integrating the robot foot structure of Embodiment 1, the adapted robot's leg joints and transmission mechanism are effectively protected when performing dynamic actions such as walking, running, and jumping. Movement stability and terrain adaptability are significantly improved, and overall service life and operational reliability are greatly enhanced.

[0039] Example 3 This embodiment discloses a robot, particularly a bipedal humanoid robot, including one or more leg assemblies of Embodiment 2. By integrating the leg assemblies of Embodiment 2, the robot's leg joints and transmission mechanisms are effectively protected when performing dynamic actions such as walking, running, and jumping. This significantly improves movement stability and terrain adaptability, and greatly enhances overall service life and operational reliability.

[0040] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention. Technical aspects, shapes, and structures not described in detail in this invention are all well-known technologies.

Claims

1. A robot foot structure, characterized in that: The system includes a foot body (1), a shock-absorbing buffer layer (2), a connecting base plate (3), a buffer connector, and a bottom buffer layer (4). The connecting base plate (3) connects the shock-absorbing buffer layer (2) to the bottom of the foot body (1) through the buffer connector. The connecting base plate (3) can move vertically relative to the foot body (1) under the action of the buffer connector. The bottom buffer layer (4) is connected to the bottom of the connecting base plate (3) and is used to directly contact the action surface. The bottom buffer layer (4) is used to achieve initial buffering while increasing the friction with the contact surface. The shock-absorbing buffer layer (2) is used to achieve secondary buffering. The shock-absorbing buffer layer (2) is a non-Newtonian fluid material layer. The non-Newtonian fluid material layer can buffer and absorb energy when subjected to impact force. The bottom buffer layer (4) is a negative Poisson's ratio structure formed by non-Newtonian fluid material, which can instantly harden and absorb impact energy while increasing the friction with the action surface when subjected to impact force.

2. The robot foot structure according to claim 1, characterized in that: The foot body (1) includes a foot plate (11) and an ankle connector (12); the ankle connector (12) is vertically connected to the foot plate (11).

3. The robot foot structure according to claim 2, characterized in that: The buffer connector includes several guide posts (5) and a locking member; the bottoms of several guide posts (5) are evenly spaced and fixedly connected to the connecting base plate (3); the foot plate (11) is provided with several first through holes; the shock-absorbing buffer layer (2) is provided with several second through holes; the guide posts (5), the first through holes and the second through holes correspond one-to-one; several guide posts (5) are installed on the foot plate (11) after passing through the second through holes and the first through holes in sequence; the locking member can be fixedly connected to the upper end of the guide posts (5) to restrict the connecting base plate (3) and the shock-absorbing buffer layer (2) from detaching from the foot plate (11).

4. The robot foot structure according to claim 3, characterized in that: The locking component includes a screw (6), a washer (7), and an oil-free bushing (8); the top of the guide post (5) is provided with a threaded hole; the lower part of the oil-free bushing (8) is fitted onto the guide post (5); the upper part of the oil-free bushing (8) is larger than the diameter of the first through hole; the screw (6) passes through the washer (7) and engages with the threaded hole for fixed connection, thereby fixing the locking component to the upper end of the guide post (5).

5. The robot foot structure according to claim 1, characterized in that: The shock-absorbing buffer layer (2) includes at least two buffer layers; a rigid connection layer (23) is provided between two adjacent buffer layers.

6. The robot foot structure according to claim 5, characterized in that: The buffer layer is a non-Newtonian fluid material layer.

7. A leg assembly, characterized in that: The robot foot structure includes any one of claims 1 to 6.

8. A robot, characterized in that: Includes the leg assembly as described in claim 7.

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