Corrugated tube based gravity self-driven robot flexible foot end structure and control method

Abstract

The application belongs to the technical field of bionic flexible robots, and discloses a gravity self-driving robot flexible foot end structure based on a bellows and a control method. The gravity self-driving robot flexible foot end structure comprises a passive compression component located in the upper half and a ground gripping toe located at the bottom. The passive compression component in the upper half is compressed, so that the internal air pressure changes, and then the ground gripping toe located at the bottom is bent and deformed, the force direction of the toe is changed, the ground is clamped, and the contact area with the irregular ground is increased. The flexible foot end designed by the application has the advantages of light weight, small volume, simple structure, strong universality, good damping and buffering performance, strong ground gripping force, and the ability to fully utilize the gravity to improve the ground gripping ability of the robot. The deformation of the bellows cavity and the internal gas flow reduce the impact of the ground on the robot body, so that the robot can adapt to various complex unstructured terrains, and the foot-ground adaptability of the foot-type robot is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of biomimetic flexible robot technology, and particularly relates to a flexible foot structure and control method for a gravity-driven self-propelled robot based on a bellows. Background Technology

[0002] As the application environments of footed robots become increasingly complex, traditional rigid structures are no longer sufficient to meet the needs of their tasks. Faced with the rigid impacts of the external environment, rigid structures struggle to conserve and recover joint energy, leading to damage to the robot body and internal sensors due to impact vibrations. Current research has improved the joint and foot structures of robots by adding flexible units to the joint actuators or foot structures to mitigate impacts. However, flexible foot ends are rare, or even nonexistent.

[0003] Existing flexible joint technologies are inherently complex and bulky, making them more suitable for specific types of robots and generally difficult to apply to other legged robots. While significant progress has been made in the application research of flexible joint robots, research on the flexible foot portion remains lacking.

[0004] Based on the above analysis, the problems and shortcomings of the existing technology are as follows:

[0005] (1) Existing technologies use other drives to provide force to enhance grip (such as using motors or servos).

[0006] (2) Existing technology cannot control the gripping toe damping by calculating the size of the air holes, and cannot improve the cushioning and shock absorption capacity of the foot.

[0007] (3) Existing technologies have poor grip, resulting in poor contact between the toes and the ground, and cannot significantly enhance foot support on complex, unstructured terrain. A key advantage of this invention is its ability to improve grip and increase friction.

[0008] (4) Existing flexible foot technology has a low degree of modularity, making it inconvenient to disassemble and replace. The foot has poor versatility and universality. Summary of the Invention

[0009] To overcome the problems existing in related technologies, the present invention discloses a flexible foot structure and control method for a gravity-driven self-propelled robot based on a bellows.

[0010] The technical solution is as follows: a flexible foot structure for a gravity-driven self-propelled robot based on a corrugated pipe, including a passive compression component located at the upper part of the flexible foot structure and a gripping toe located at the bottom of the flexible foot structure. The passive compression component is flexibly connected to the gripping toe through a connecting joint. By compressing the passive compression component, the air pressure inside the passive compression component changes, causing the gripping toe to bend and deform, and changing the force direction of the gripping toe, thereby increasing the contact area with the irregular ground.

[0011] In one embodiment, the flexible toe-gripping base has a groove at the connection point between the upper part of the connecting joint and the passive compression component, the groove being used to fix the passive compression component.

[0012] In one embodiment, the interface for fixing the gripping toe at the connecting joint is provided with multiple protruding interfaces composed of mortise and tenon structures. These protruding interfaces are used to fix and position the gripping toe. The multiple protruding interfaces are evenly arranged around the circumference of the connecting joint.

[0013] In one embodiment, the connecting joint has an air passage in the middle, and the size of the air vents in the air passage is proportional to the length of the air vents. The damping of the foot tip for gripping the toes is controlled by calculating the size of the air vents.

[0014] In one embodiment, the gripping toe has multiple interconnected air chambers inside;

[0015] The gripping toes are multiple in number, and the size of the gripping toes gradually decreases from the base to the tip; a toe-contacting rubber surface is also provided at the bottom of the gripping toes.

[0016] In one embodiment, the base is connected to the gripping toes via a groove.

[0017] In one embodiment, the passive compression component adopts a U-shaped bellows structure, and the height-to-width ratio of the passive compression component ranges from 0.5 to 1.5.

[0018] Another objective of this invention is to provide a control method for realizing the flexible foot structure of the gravity self-driving robot based on the bellows. The control method includes: compressing a passive compression component to change the air pressure inside the passive compression component, causing the gripping toes to bend and deform, changing the direction of force exerted by the gripping toes on the ground, and increasing the contact area with the irregular ground.

[0019] In one embodiment, the passive compression component is movably connected to the gripping toe via a connecting joint. An air passage is connected in the middle of the connecting joint, and the size of the air vents in the air passage is proportional to the length of the air vents. The damping effect of the gripping toe is controlled by the calculated air vent size, thereby changing the cushioning and vibration reduction capabilities of the gripping toe.

[0020] In one embodiment, controlling the damping effect of the gripping toe by calculating the pore size, thereby altering the cushioning and shock absorption capabilities of the gripping toe, includes:

[0021] When the flexible foot end is not under force, the upper part of the corrugated ankle is in an uncompressed state, and the contact surface between the upper end of the corrugated ankle and the body is at reference point 0. When the flexible gripping foot end is under force, assuming the downward compression direction of the flexible gripping foot end is positive, then the gas volume of the upper and lower parts of the flexible foot end is:

[0022] V ankle =V ankle0 -sx

[0023] V toe =V toe0 -f(P toe (1)

[0024] In the formula, V ankle V toe These represent the real-time internal gas volumes of the flexible grip foot, ankle, and toes; V ankle0 V toe0 denoted as , where is the initial internal gas volume of the ankle and toes when the flexible grip foot is not compressed; s is the effective cross-sectional area of ​​the ankle portion of the flexible grip foot; x is the compression displacement of the ankle portion of the flexible grip foot under force; f(P) toe () represents the expansion volume of the flexible gripping toe area due to increased air pressure;

[0025] According to the heterogeneous equations of an ideal gas:

[0026] PV = nrT emp (2)

[0027] In the formula, P is the gas pressure, V is the gas volume, n is the amount of substance of the gas, r is the gas constant, and T is the gas volume. emp The system temperature;

[0028] For the gas pressure P of the mixed gas, equation (2) can be written as:

[0029] PV air =n air rT emp (3)

[0030] In the formula, V air n is the gas volume in the ideal gas equation. air The amount of air in the container;

[0031] Combining formulas (1) and (3), the gas pressure changes in the upper and lower parts of the gripping foot satisfy the following:

[0032]

[0033]

[0034] P ankle0 V ankle0 +P toe0 V toe0 =P ankle (V ankle0 -sx)+P toe V toe0 (4)

[0035] In the formula, P ankle ,P toe These represent the real-time internal gas pressure at the flexible grip foot end, ankle, and toes, P ankle0 ,P toe0 These represent the air pressure values ​​for the ankle and toes in the initial state, respectively; n change n represents the amount of gaseous substance flowing from the inside of the ankle to the inside of the toes. ankle n represents the amount of gaseous material originally present inside the ankle. toe The amount of gaseous substance originally inside the toes;

[0036] Based on the compressibility of air and the continuity of airflow mass flow rate, the relationship between the gas mass and the changes in gas pressure and volume within the flexible ankle air cavity is obtained as follows:

[0037]

[0038] In the formula, G z This refers to the gas mass flow rate in the flexible foot end, inside the ankle region. This refers to the rate of change of air pressure in the ankle; T represents the rate of change of gas volume inside the ankle; ankle0 The initial temperature of the foot and ankle system;

[0039] The gas in the air chambers of the foot, ankle, and toes exchanges through a central damping orifice. The pressure and gas velocity in the orifice are approximately equal to the pressure and gas velocity at the toes. According to Bernoulli's equation:

[0040]

[0041] In the formula, ξ toe The local drag coefficient is ρ, where ρ is the gas density at the flexible foot tip; g is the acceleration due to gravity; and a is the gas flow rate. ankle a is the flow coefficient of the flow contraction section at the ankle of the damping orifice. toe The flow coefficient, v, at the flow contraction section of the damping orifice toe. ankle v is the gas velocity at the ankle-foot contraction section. toe The gas velocity at the toe contraction section. The square of the gas velocity at the ankle-contraction section. The square of the gas velocity at the toe contraction section;

[0042] Based on the uniform velocity distribution on the contracted cross-section of the orifice, a ankle =1, a toe =1; therefore:

[0043]

[0044] In the formula, C v Let denoted as the orifice velocity coefficient, and Δp as the foot-to-ankle pressure difference, based on the area a of the minimum flow passage. c The ratio of the flow cross-sectional area a of the small orifice to C is c Then we have a c =C c a. The flow rate formula for the short-hole damping orifice is obtained as follows:

[0045]

[0046] In the formula, q c For the flow rate of the short-hole damping orifice, C q C is the orifice flow coefficient; c It is the area a of the minimum flow passage. c The ratio of the orifice flow cross-sectional area a; v c is the flow velocity at the minimum flow cross section, and a is the flow cross area of ​​the orifice;

[0047] The gas mass flow rate in the damping orifice of the flexible ankle section is:

[0048]

[0049] Where ρ0 is the gas density in the initial state;

[0050] The transient rate of change of air pressure inside the flexible ankle section can be expressed using formulas (5) and (9):

[0051]

[0052] The transient rate of change of air pressure inside the toes is:

[0053]

[0054] In the formula, T represents the transient rate of change of air pressure inside the toes. toe0 and V toe These represent the initial temperature of the gas inside the flexible foot toe and the real-time gas volume in the flexible foot toe portion under this state.

[0055] The expression for the nonlinear stiffness of the ankle portion is:

[0056]

[0057] In the formula, K is the nonlinear stiffness. For the rate of change of force, For speed, Let A be the rate of change of air pressure in the ankle and foot, and let A be the effective cross-sectional area of ​​the ankle and foot.

[0058] Another objective of this invention is to provide a high-altitude terrain climbing robot equipped with the aforementioned corrugated pipe-based gravity-driven robot flexible foot structure, as well as a high-corrosion and harsh environment emergency repair robot.

[0059] Combining all the above technical solutions, the advantages and positive effects of this invention are as follows:

[0060] First, in view of the technical problems existing in the prior art and the difficulty of solving these problems, and closely combining the technical solution to be protected by this invention with the results and data during the research and development process, this paper analyzes in detail how the technical solution of this invention solves the technical problems, and the inventive technical effects brought about after solving the problems, as described in detail below:

[0061] This invention discloses a gravity-driven flexible foot structure for robots, including a passive compression component and gripping toes. A corrugated air chamber is connected to the air chamber inside the gripping toes by a base, forming a complete and sealed internal gas circuit within the foot. During robot movement, the foot is subjected to gravity and body forces, contacting the ground. The passive compression component deforms under these forces, providing cushioning displacement for the robot body and foot, effectively reducing the impact of the ground on the robot body. Simultaneously, the deformation of the passive compression component causes a change in air pressure within the foot's internal air circuit, pushing the gas in the corrugated air chamber into the gripping toes, thus forcing the toes to bend inward. Due to the varying wall thickness of the internal air chambers within the gripping toes, the toes exhibit a greater degree of bending at the root and a smaller degree of bending at the tip under air pressure. In this state, the gripping toes interact with the ground and adhere closely to different unstructured surfaces, increasing the contact area between the foot structure and the ground. By altering the direction of force exerted by individual toes, the foot's grip is enhanced, improving its adaptability to different environments. This achieves the goal of improving grip. Simultaneously, during the gas conduction process within the corrugated air chamber, a significant amount of energy is consumed through the gas pathway, providing excellent cushioning and shock absorption performance for the foot.

[0062] The flexible foot designed in this invention is lightweight, compact, simple in structure, highly versatile, has good vibration damping and cushioning performance, and strong grip, fully utilizing its own weight to improve the robot's ground grip. The corrugated air cavity deformation and internal gas flow can reduce the impact of the ground on the robot body, enabling it to adapt to various complex unstructured terrains. Especially when facing softer terrain surfaces such as snow, sand, and swamps, it greatly improves the foot adaptability of legged robots.

[0063] Secondly, considering the technical solution as a whole or from the perspective of the product, the technical effects and advantages of the technical solution to be protected by this invention are specifically described as follows:

[0064] The structure provided by this invention has the characteristics of being lightweight, small in size, simple in structure, highly versatile, with good vibration damping and buffering performance, strong grip, and strong adaptability to unstructured ground. It can be applied to the field of vibration damping and buffering and multi-terrain adaptation in the field of outdoor legged mobile robots.

[0065] The innovation of this invention lies in providing a flexible foot structure. The upper part contains a compressible, recoverable air bladder, which can be compressed to change the internal air pressure. This, in turn, affects the bending deformation of the toes at the bottom, altering the direction of force applied by the toes to grip the ground and increasing the contact area with irregular surfaces. Cushioning and vibration reduction are also crucial aspects for mobile legged robots.

[0066] Most previous studies have used electric motors or servo motors for driving, which require an additional power source. The innovation of this invention lies in a method to improve grip without an additional power source.

[0067] Third, as supplementary evidence of the inventive step of the claims of this invention, it is also reflected in the following important aspects:

[0068] (1) This invention adopts a modular design, which is lightweight, simple, easy to install and replace. When mounted on a legged mobile robot, it requires no additional assembly parts, greatly improving the stability and gripping ability of the legged robot. In addition, the production is simple and the raw materials are readily available, which ensures a certain level of manufacturing cost for this invention. It can replace existing non-stress-mode robot legs on the market on a large scale.

[0069] (2) This invention creatively reuses the buffer and vibration reduction module as an output drive source to improve grip, which is the first of its kind at home and abroad.

[0070] (3) Compared with traditional robot feet without strain or with driving elements, this invention largely solves the problem of insufficient gripping force leading to slippage, rollover or excessive and redundant control signals when legged robots are supporting and moving. It provides technical support for the research and development and use of legged robots that are simpler, more stable and faster.

[0071] (4) This invention breaks the long-standing monopoly of footed robot vibration-damping flexible joints and active strain-type foot ends, and achieves an innovative technological breakthrough in the field of robot flexible foot ends. Attached Figure Description

[0072] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure;

[0073] Figure 1 This is a schematic diagram of the flexible foot structure of a gravity-driven self-propelled robot based on a bellows, provided in an embodiment of the present invention.

[0074] Figure 2 This is an exploded view of the flexible foot structure of a gravity-driven self-propelled robot based on a bellows, provided in an embodiment of the present invention.

[0075] Figure 3 This is a schematic diagram illustrating the application of the flexible foot structure of a gravity-driven self-propelled robot based on a bellows in toe fixation, as provided in an embodiment of the present invention.

[0076] Figure 4(a) is a schematic diagram of the displacement change of the foot end provided in the embodiment of the present invention;

[0077] Figure 4(b) is a schematic diagram of pressure changes in the toes provided in an embodiment of the present invention;

[0078] Figure 5(a) is an analysis diagram of the influence of different passive compression component heights on the vibration variation characteristics of the flexible foot end provided by the embodiment of the present invention;

[0079] Figure 5(b) is an analysis diagram of the influence of different passive compression component heights on the air pressure supply characteristics of the flexible foot end provided by an embodiment of the present invention;

[0080] Figure 5(c) is a schematic diagram of the displacement of the flexible foot end under different passive compression component radius lengths provided in the embodiment of the present invention;

[0081] Figure 5(d) is a schematic diagram of the air pressure supply at the flexible foot end under different passive compression component radius lengths provided in the embodiment of the present invention;

[0082] Figure 5(e) is a schematic diagram of the displacement of the flexible foot end in the embodiment of the present invention, since the damping hole is an important linking device connecting the upper and lower parts;

[0083] Figure 5(f) is a schematic diagram of the air pressure supply at the flexible foot end in an embodiment of the present invention, since the damping hole is an important linking device connecting the upper and lower parts.

[0084] Figure 5(g) is a simulation result diagram of the vibration displacement analysis of flexible foot end with different internal air cavity volumes of flexible toes provided by the embodiment of the present invention;

[0085] Figure 5(h) is a simulation result diagram of the pressure supply analysis of the flexible foot end for different internal air cavity volumes of the flexible toe provided by the embodiment of the present invention;

[0086] In the diagram: 1. Passive compression component; 2. Connecting joint; 3. Grip toe; 4. Base; 5. Toe contact rubber surface. Detailed Implementation

[0087] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0088] I. Explanation of the Implementation Example:

[0089] like Figure 1 As shown, this embodiment of the invention provides a flexible foot structure for a gravity-driven self-propelled robot based on a corrugated pipe, including a passive compression component 1 located in the upper part and a gripping toe 3 located at the bottom. The passive compression component 1 in the upper part compresses the air, causing a change in the internal air pressure, which in turn affects the gripping toe 3 located at the bottom to produce bending deformation, changes the force direction of the toe, and increases the contact area with the irregular ground.

[0090] The passive compression component 1 is movably connected to the gripping toe 3 via the connecting joint 2; the gripping toe 3 is flexibly fitted into the base 4.

[0091] Example 1

[0092] like Figures 1-2 As shown, the flexible foot structure of the gravity self-driving robot based on the corrugated pipe provided in this embodiment of the invention includes: a passive compression component 1, a connecting joint 2, a gripping toe 3, a base 4, and a toe contact surface 5.

[0093] By utilizing the robot's own weight, impact force, and the deformation characteristics of the passive compression component 1, the impact on the ground can be reduced, thus extending the robot's service life.

[0094] In a preferred embodiment of the invention, the passive compression component 1 is connected to the air chamber inside the gripping toe 3, forming a complete gas circuit inside the foot end of the gripping toe 3.

[0095] The passive compression component 1 deforms under pressure, pushing the gas inside the passive compression component 1 toward the gripping toe 3 (gripping flexible toe), thereby forcing the gripping toe 3 to bend inward, forming a downward gripping force, increasing the contact area with the irregular ground, and enhancing the support effect and stability of the foot end of the gripping toe 3.

[0096] In a preferred embodiment of the invention, the base 4 is divided into upper and lower parts, which are used to fix the passive compression component 1 and the gripping toe 3, respectively.

[0097] Wherein, A. at the connection point between the upper half of the connecting joint 2 and the passive compression component 1, a groove is provided for fixing the passive compression component 1, ensuring the stability of the passive compression component 1 and the airtightness of the internal air chamber.

[0098] B. A protruding interface is designed at the interface where the connecting joint 2 fixes the gripping toe 3, for fixing and positioning the gripping toe 3. A tenon and mortise structure is designed at the base 4 for fixing the gripping toe 3 to the connecting joint 2.

[0099] C. The air passage is connected in the middle of the connecting joint 2 structure. The size of the air hole is in a certain proportion to the length of the air hole. The damping effect of the gripping toes 3 can be controlled by calculating the size of the air hole, thereby improving the cushioning and shock absorption capacity of the foot.

[0100] This invention provides a control method for a flexible foot structure of a gravity-driven self-propelled robot based on a bellows, comprising: compressing the upper part by a passive compression component 1, causing a change in the internal air pressure, thereby affecting the bending deformation of the gripping toes 3 located at the bottom, changing the force direction of the toes, and increasing the contact area with the irregular ground.

[0101] The passive compression component 1 is flexibly connected to the gripping toe 3 via the connecting joint 2; the connecting joint 2 is connected to the air passage in the middle, and the size of the air hole in the air passage is in a certain proportion to the length of the air hole. The damping effect of the gripping toe 3 is controlled by the calculated air hole size, thereby enhancing the cushioning and vibration reduction capabilities of the gripping toe 3.

[0102] In this embodiment of the invention, the effect of the pore size in controlling the damping of the gripping toes can be understood as a pneumatic-force relationship:

[0103] When the flexible foot end is not under force, the upper part of the corrugated ankle is in an uncompressed state, and the contact surface between the upper end of the corrugated ankle and the body is at reference point 0. When the flexible gripping foot end is under force, assuming the downward compression direction of the flexible gripping foot end is positive, then the gas volume of the upper and lower parts of the flexible foot end is:

[0104] V ankle =V ankle0 -sx

[0105] V toe=V toe0 -f(P toe (1)

[0106] In the formula, V ankle V toe These represent the real-time internal gas volumes of the flexible grip foot, ankle, and toes; V ankle0 V toe0 s represents the initial internal gas volume of the ankle and toes when the flexible grip foot is not compressed; s is the effective cross-sectional area of ​​the ankle portion of the flexible grip foot; x is the compression displacement of the ankle portion of the flexible grip foot under force; f(P) toe f(P) represents the expansion volume of the flexible gripping toe area due to increased air pressure. toe The slight change in volume of the flexible gripping toe caused by the change in air pressure is negligible because its impact on the overall gas volume change is small.

[0107] According to the heterogeneous equations of an ideal gas:

[0108] PV = nrT emp (2)

[0109] In the formula, P is the gas pressure, in Pa; V is the gas volume, in m³. 3 n is the amount of substance of the gas, in mol; T emp The system temperature is in K; r is the gas constant in J (mol·K). For a gas mixture, the pressure P is a linear combination of the partial pressures of its components. Equation (2) can be written as:

[0110] PV air =n air rT emp (3)

[0111] In the formula, V air n is the gas volume in the ideal gas equation. air The amount of air in the container;

[0112] Combining formulas (1) and (3), the gas pressure changes in the upper and lower parts of the gripping foot satisfy the following:

[0113]

[0114]

[0115] P ankle0 V ankle0 +P toe0 V toe0 =P ankle (V ankle0 -sx)+P toe Vtoe0 (4)

[0116] In the formula, P ankle ,P toe These represent the real-time internal gas pressure at the flexible grip foot end, ankle, and toes, P ankle0 ,P toe0 These represent the air pressure values ​​for the ankle and toes in the initial state, respectively; n change n represents the amount of gaseous substance flowing from the inside of the ankle to the inside of the toes. ankle n represents the amount of gaseous material originally present inside the ankle. toe The amount of gaseous substance originally inside the toes;

[0117] Based on the compressibility of air and the continuity of airflow mass flow rate, the relationship between the gas mass and the changes in gas pressure and volume within the flexible ankle air cavity is obtained as follows:

[0118]

[0119] In the formula, G z This refers to the gas mass flow rate in the flexible foot end, inside the ankle region. This refers to the rate of change of air pressure in the ankle; T represents the rate of change of gas volume inside the ankle; ankle0 The initial temperature of the foot and ankle system;

[0120] The gas in the air chambers of the foot, ankle, and toes exchanges through a central damping orifice. The pressure and gas velocity in the orifice are approximately equal to the pressure and gas velocity at the toes. According to Bernoulli's equation:

[0121]

[0122] In the formula, the diameter D of the bellows foot is greater than the diameter d of the damping orifice, v ankle ≈0, ξ toe The local drag coefficient is ρ, where ρ is the gas density at the flexible foot tip; g is the acceleration due to gravity; and a is the gas flow rate. ankle a is the flow coefficient of the flow contraction section at the ankle of the damping orifice. toe The flow coefficient, v, at the flow contraction section of the damping orifice toe. ankle v is the gas velocity at the ankle-foot contraction section. toe The gas velocity at the toe contraction section. The square of the gas velocity at the ankle-contraction section. The square of the gas velocity at the toe contraction section;

[0123] Based on the uniform velocity distribution on the contracted cross-section of the orifice, a ankle =1, a toe =1; therefore:

[0124]

[0125] In equation (7), C v Let denoted as the orifice velocity coefficient, and Δp as the foot-to-ankle pressure difference, based on the area a of the minimum flow passage. c The ratio of the flow cross-sectional area a of the small orifice to C is c Then we have a c =C c a. The flow rate formula for the short-hole damping orifice is obtained as follows:

[0126]

[0127] In the formula, q c For the flow rate of the short-hole damping orifice, C q C is the orifice flow coefficient; c It is the area a of the minimum flow passage. c The ratio of the orifice flow cross-sectional area a; v c is the flow velocity at the minimum flow cross section, and a is the flow cross area of ​​the orifice;

[0128] The gas mass flow rate in the damping orifice of the flexible ankle section is:

[0129]

[0130] Where ρ0 is the gas density in the initial state;

[0131] The transient rate of change of air pressure inside the flexible ankle section can be expressed using formulas (5) and (9):

[0132]

[0133] The transient rate of change of air pressure inside the toes is:

[0134]

[0135] In the formula, T represents the transient rate of change of air pressure inside the toes. toe0 and V toe These represent the initial temperature of the gas inside the flexible foot toe and the real-time gas volume in the flexible foot toe portion under this state.

[0136] The expression for the nonlinear stiffness of the ankle portion is:

[0137]

[0138] In the formula, K is the nonlinear stiffness. For the rate of change of force, For speed, Let A be the rate of change of air pressure in the ankle, and T be the effective cross-sectional area of ​​the ankle. ankle0 V represents the initial temperature of the foot and ankle. ankle P represents the real-time gas volume in the air cavity of the flexible foot and ankle portion under this state. ankle Real-time gas pressure at the ankle and foot end for flexible grip.

[0139] In a preferred embodiment of the invention, the gripping toes 3 are evenly distributed in a circular pattern, and are fixed to the connecting joint 2 using a mortise and tenon structure. This greatly improves the gripping toes' ability to connect with the joint, and the even circular distribution of the gripping toes 3 significantly enhances its adaptability to unstructured surfaces. It also greatly reduces the directional bias of the gripping toes 3, giving the robot stronger grip and climbing ability.

[0140] In a preferred embodiment of the invention, the thickness of the individual toe segments and the width of the gaps within the gripping toe 3 vary, resulting in different degrees of curvature of the individual toe segments under the influence of internal air pressure. This allows for a higher degree of contact between the toe-contact rubber surface 5 connected to the gripping toe 3 and the ground, greatly enhancing the support of the foot on complex, unstructured terrain.

[0141] Compared to existing technologies, the flexible foot end provided in this embodiment of the invention adopts a modular approach, making it easier to disassemble and replace. This improves the versatility and universality of the overall structure.

[0142] Example 2

[0143] like Figures 1-2 As shown, in the flexible foot structure of the gravity self-driving robot based on the bellows provided in this embodiment of the invention, the passive compression component 1 and the gripping toe 3 form a closed foot gas circuit isolated from the outside world under the action of the connecting joint 2.

[0144] This gas circuit controls the gripping degree of the gripping toes 3 on the ground by changing the internal air pressure.

[0145] The connecting joint 2 is divided into upper and lower parts, which are used to fix the passive compression component 1 and the gripping toe 3 respectively. At the connection between the upper part of the connecting joint 2 and the passive compression component 1, there is a groove for fixing the passive compression component 1, ensuring the stability of the passive compression component 1 and the sealing of the internal air chamber.

[0146] At the interface where the connecting joint 2 fixes the gripping toe 3, a protruding interface is designed to facilitate fixing and positioning the gripping toe 3. A tenon and mortise structure is designed at the base 4 of the connecting structure to strengthen and secure the gripping toe 3, ensuring a tight connection between it and the connecting structure.

[0147] Example 3

[0148] The flexible foot structure for a gravity-driven self-propelled robot based on a bellows provided by this invention operates primarily by converting the gravity and impact forces experienced by the robot and its gripping toe 3 into ground-gripping forces, thereby enhancing the cushioning capacity of the gripping toe 3. Each main structural component performs a specific function of the flexible foot. Details are as follows:

[0149] In this embodiment of the invention, the passive compression component 1 plays a crucial role in energy absorption and conversion within the entire structure, and is also an important component of the overall structural force conversion. When the foot contacts the ground, the foot end of the gripping toe 3 undergoes compression deformation under the action of gravity and impact force. Under the action of deformation, the volume of its internal air cavity decreases, and the internal pressure increases, providing stable support for the robot. At the same time, the gas in the air cavity absorbs the energy of gravity and impact force and converts it into the inward gripping ability of the gripping toe 3. Due to the special structure of the U-shaped corrugated tube, the corrugated tube can provide stable support while bending at a certain angle after being subjected to force.

[0150] Design Scheme: The passive compression component 1 plays a crucial role in the energy conversion of the entire flexible foot end and the force conversion of the gripping toe 3. The internal air cavity volume should be significantly larger than the internal air cavity volume of the gripping toe 3 to reduce the impact of the gripping toe 3's internal air cavity on the passive compression component 1. The height and width of the passive compression component 1 are in a certain proportion, with the height ranging from 0.5 to 1.5 times the width. Within this range, the air cavity of the passive compression component 1 can provide sufficient internal air pressure volume. The corrugation pitch of the bellows in the passive compression component 1 affects the degree of ankle flexion within it. The degree of flexibility and compression is maximized when the distance between the crests and troughs is uniformly equal. When the passive compression component 1 is connected to the connecting joint 2, a special groove is designed. Utilizing the tensile and ductile properties of the passive compression component 1 material, the connecting joint 2 is nested into the ankle of the passive compression component 1. This facilitates the connection between the passive compression component 1 and the connecting joint 2, ensuring a sealed environment and guaranteeing the airtightness and integrity of the internal air cavity.

[0151] In this embodiment of the invention, the structural mechanism of the gripping toe 3 is as follows: The gripping toe 3 plays a crucial role in energy output within the flexible foot end. When the passive compression component 1 is compressed, the volume of its internal air cavity decreases, causing compression of the internal gas and an increase in gas pressure. This increased gas pressure within the gripping toe 3 causes the internal air cavity to expand. Due to the thin wall between the two connected individual air cavities within the gripping toe 3, as the gas pressure increases, the gripping toe 3 expands at the adjacent point. When the expansion reaches a certain extent, the mutual compression causes the gripping toe 3 to bend.

[0152] Design Scheme: The gripping toe 3 is responsible for transferring foot force. When the gas pressure increases, the gripping toe 3 bends and adheres tightly to the ground. Considering the unstructured nature of the ground, the gripping toe 3 is designed in a trapezoidal shape, with a thicker base and a thinner tip. This allows the gripping toe 3 to adhere more closely to the ground, providing a more reliable grip on terrain with cracks or fissures.

[0153] Simultaneously considering the interaction between the ground and the gripping toe 3, the gripping toe 3 bends to varying degrees under gas pressure. This is achieved by altering the wall thickness of individual air chambers within the gripping toe 3 and the distance between those chambers. The wall thickness and the distance between the air chambers can be adjusted according to the user's needs.

[0154] The reduced wall thickness increases the expansion ratio of the air cavities; the reduced distance between the air cavities results in different degrees of bending per unit expansion volume. The bottom of the gripping toe 3 is provided with a toe-contact rubber surface 5 to increase friction by adding a textured pattern.

[0155] In the embodiment of the invention, the connecting joint 2 works as follows: the connecting joint 2 is used to fix the gripping toe 3 and the passive compression component 1, while the gas connection channel therein is used to connect the air chamber of the gripping toe 3 and the passive compression component 1, so that the flexible foot end forms a closed gas passage. The gas connection channel triggers the small hole damping effect through the size of the aperture, thereby achieving the functions of energy consumption and shock absorption.

[0156] Design Scheme: To facilitate the even distribution of gripping toes 3 on all sides and to allow for a certain tilt angle, the flexible connecting joint 2 is designed as a semi-ellipsoid. Its upper half has a groove for fixing the passive compression component 1. Its lower half has a fixing groove for the gripping toes 3, and a protrusion at the connection point with the gripping toes 3 for fixing and positioning the gripping toes 3. The size of the central aperture can be calculated using Bernoulli's equation based on the robot's load capacity and gas transmission efficiency.

[0157] In this embodiment of the invention, the base 4 has the following structural mechanism: it is used to fix the gripping toe 3, and is assembled with the gripping toe 3 using the groove to ensure the stability and reliability of the gripping toe 3.

[0158] Design scheme: A groove is designed to fit snugly into the gripping toe 3, which has a special structure. This ensures that the gripping toe 3 will not fall off after the internal gas pressure increases, thus guaranteeing the reliability of the entire structure's airtightness.

[0159] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0160] The information interaction and execution process between the above-mentioned devices / units are based on the same concept as the method embodiments of the present invention. For details on their specific functions and technical effects, please refer to the method embodiments section, and they will not be repeated here.

[0161] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this invention. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments.

[0162] II. Application Examples:

[0163] Application Example 1

[0164] This invention provides a flexible foot structure for an outdoor legged mobile robot adapted to complex unstructured terrain. This flexible structure possesses excellent versatility and can effectively replace traditional rigid foot structures and flexible joints that can only be used in specific robots. Furthermore, this flexible foot structure can achieve good cushioning and shock absorption performance without additional drive, effectively improving the service life of the robot's body structure and internal precision equipment.

[0165] Application Example 2

[0166] The gravity-driven flexible foot structure designed in this embodiment of the invention can effectively replace the traditional rigid foot structure and flexible joints that can only be used in specific robots.

[0167] It is an alternative, requiring no special robot design for this structure, and possesses good versatility and universality. Due to its light weight, small size, simple structure, good vibration damping and cushioning performance, strong grip, and strong adaptability to unstructured ground, it enables outdoor legged robots to adapt to more complex unstructured terrain and steep slopes. The structure can fully utilize the energy of the gas within the internal air chamber for conversion and elimination, reducing vibration and impact at the foot end, and improving the service life of the robot's body structure and internal components.

[0168] Application Example 3

[0169] Figure 3 This invention relates to the application of a corrugated tube-based gravity-driven robot flexible foot structure in toe fixation.

[0170] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0171] III. Evidence of the relevant effects of the embodiments:

[0172] First, the model parameters were analyzed using the controlled variable method, clarifying the influence of the main model parameters on the buffer vibration reduction frequency and the supply air pressure. Then, based on the model dynamic equations, a coupling relationship diagram between the model parameters under the expected period was drawn. Subsequently, based on the coupling relationship diagram, a point-sampling method was used to coordinate the selection of model parameters. Figure 4(a) shows a schematic diagram of the vibration displacement change at the foot end. Figure 4(b) shows a schematic diagram of the pressure change at the toes.

[0173] In this embodiment, the robot's overall mass is 6 kg, and it uses a three-legged gait, meaning each supporting leg weighs 2 kg. The passive compression component 1 has a height of 30 mm, an ankle wave height radius of 22.5 mm, and a wave trough radius of 17.5 mm, as an example. The foot is allowed to fall normally when the initial internal air pressure is the same as the external air pressure. The design of the passive compression component 1, the flexible toes, and the damping holes of different diameters will affect the changes in gas flow between structures, further influencing the vibration characteristics of the foot structure and the air pressure supply characteristics to the toes. The specific design will be determined based on the robot's weight and the selected application scenario.

[0174] During the robot's downward compression, the flexible foot experiences force displacement, pressure changes, and a compression trajectory. Initially, the flexible foot just contacts the ground, at which point the ankle portion is compressed, increasing the air pressure within its internal air chamber and creating a pressure difference with the toe portion. This pressure difference between the two portions changes. Releasing a portion of the gas pressure from the passive compression component provides gas pressure to the toes, driving their flexion and improving the foot's grip. Simultaneously, the damping orifice dissipates energy during the conversion of gravitational potential energy into kinetic potential energy. This reduces the conversion between kinetic and elastic potential energy, improving the flexible foot's cushioning and shock absorption capabilities. It also allows the toes to receive a pressure source that interacts with the ground.

[0175] The main model parameters affecting the grip and shock absorption performance of the flexible foot end include the flow rate between the upper and lower parts of the flexible foot end and the volume ratio of the ankle to the toes. Among these, the orifice diameter of the damping orifice influences the flow rate between the ankle and toes. The flow rate is affected by both the flow velocity and cross-sectional area within the damping orifice; the cross-sectional area is influenced by the orifice diameter, while the flow velocity is influenced by the medium and the pressure difference between the upper and lower ends. The influence of the controlled variable method on the shock absorption performance and ankle pressure supply performance under the main model parameters was simulated. The simulation parameters are set as shown in Table 1, and the simulation results correspond to... Figures 5(a)-5(h) ;

[0176] Table 1 Simulation parameter settings

[0177]

[0178] Figure 5(a) analyzes the influence of different passive compression component 1 heights on the vibration characteristics of the flexible foot end; Figure 5(b) analyzes the influence of different passive compression component 1 heights on the air pressure supply characteristics of the flexible foot end. The heights of the passive compression component 1 are taken as 20mm, 35mm, and 50mm, and other model parameters are shown in Table 1. Figures 5(a)-5(b) As shown in the diagram, the higher the passive compression component 1 is, the greater its vibration displacement and the longer its vibration time. This is because as the passive compression component 1 becomes taller, the larger the gas space inside the ankle, and the greater the displacement required to compress to the same air pressure under stress. This reduces the robot's stability, and the slower rate of air pressure change in the ankle leads to a slower flow rate through the damping orifice, resulting in slower gas exchange with the toes and slower energy consumption. In summary, an excessively high passive compression component 1 causes the flexible foot to enter an underdamped state, resulting in a longer balancing time.

[0179] The model parameters are defined in Table 1. Figures 5(c)-5(d) As shown in Figure 5(c), the displacement of the flexible foot end is illustrated under different radii of the passive compression component 1; Figure 5(d) shows the air pressure supply to the flexible foot end under different radii of the passive compression component 1. With the bellows height and gas exchange flow rate remaining constant, increasing the radius of the passive compression component 1 is equivalent to increasing the air chamber volume of the passive compression component 1. This also allows for greater support force to the robot under the same internal air pressure changes. Although the air chamber volume of the passive compression component 1 is increased, the displacement caused by the pressure on the ankle is proportional to its pressure change rate. This means that increasing the radius of the passive compression component 1 will not slow down the air pressure change rate, and may even make it faster. This also means that the flow rate of the damping orifice will not only not slow down, but its energy consumption rate will be slightly higher. Its vibration damping effect will be stronger, and the pressure supply capacity to the toes will be stronger and more stable.

[0180] The model parameters are defined in Table 1. Figures 5(e)-5(f) As shown in the figure, the damping orifice is an important connecting device between the upper and lower parts. Its flow rate affects many crucial factors, including the stiffness and damping of the flexible foot. The flow rate is related to the flow velocity and cross-sectional area, and the flow velocity is related to the pressure difference; therefore, only the radius of the damping orifice's cross-sectional area is changed here. As the radius of the damping orifice gradually increases, the mass of gas that can pass through per unit time also increases. Figure 5(e) is a schematic diagram of the displacement of the flexible foot in the embodiment of the present invention where the damping orifice is an important connecting device between the upper and lower parts; Figure 5(f) is a schematic diagram of the air pressure supply to the flexible foot in the embodiment of the present invention where the damping orifice is an important connecting device between the upper and lower parts; from Figures 5(e)-5(f) As can be seen, the size of the damping orifice radius has a significant impact on the vibration buffering and pressure supply of the flexible foot end. When the damping orifice is small, its energy dissipation capacity is stronger, but its flow rate is smaller, and its buffering and vibration resistance is weakened. The vibration mainly originates from the passive compression component 1 above, whose internal gas mass cannot be promptly supplied to the toes below. This causes the ankle to vibrate under the action of pressure and gravity. However, when the damping orifice is too large, its energy dissipation capacity is weaker, and its buffering and vibration resistance will also be weakened to some extent. The vibration mainly originates from the gas exchange problem between the ankle and toes. A smaller radius will cause the entire foot end to have an overdamped effect, but the ankle part will have a self-vibration problem. A larger radius will cause the entire foot end to have an underdamped effect. Gas exchange between the ankle and toes occurs, but energy dissipation is smaller, resulting in a larger amplitude of foot end vibration and unstable air pressure supplied to the flexible toes. The flexible foot end cannot quickly and closely interact with the ground to improve grip.

[0181] Finally, the effects of different internal air cavity volumes of the flexible toe on the vibration and pressure supply of the flexible foot are analyzed, and the patch model parameters are shown in Table 1. Figure 5(g)-Figure 5(h) As shown in the figures, Figure 5(g) is a simulation result diagram of the analysis of the vibration displacement of the flexible foot end by different internal air cavity volumes of the flexible toe provided by the embodiment of the present invention; Figure 5(h) is a simulation result diagram of the analysis of the pressure supply of the flexible foot end by different internal air cavity volumes of the flexible toe provided by the embodiment of the present invention.

[0182] While keeping other structural elements constant, the air cavity volume of the flexible toe section is increased. Since the flexible toe interacts with the ground, the internal air cavity volume changes little with air pressure; therefore, the increase in gas flowing into it through the damping orifice results in a change in air pressure. When the air cavity volume of the flexible toe section is increased, the required air pressure to support the robot's weight remains unchanged. Therefore, the amount of gas flowing into the flexible toe section through the damping orifice necessitates a larger compression displacement in the passive compression component 1. When the internal air cavity of the flexible toe becomes larger, the effect of the same gas flow rate on air pressure changes less. Therefore, a larger internal air cavity in the flexible toe results in a more stable air pressure supplied by the ankle.

[0183] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention and within the spirit and principles of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A bellows-based gravity-autonomous robot flexible foot end structure, comprising a passive compression component (1) located at the upper part of the flexible foot end structure and a gripping toe (3) located at the bottom of the flexible foot end structure, the passive compression component (1) being flexibly connected to the gripping toe (3) through a connecting joint (2); characterized in that, The passive compression component (1) is connected with the gripping toe (3) through the connecting joint (2), the middle of the connecting joint (2) is connected with the air passage, the size of the air hole in the air passage is proportionally set with the length of the air hole, and the size of the air hole obtained by calculation controls the damping effect of the gripping toe (3), and the buffering and damping capacity of the gripping toe (3) is changed. The passive compression component (1) is connected with the gripping toe (3) through the connecting joint (2), the middle of the connecting joint (2) is connected with the air passage, the size of the air hole in the air passage is proportionally set with the length of the air hole, and the size of the air hole obtained by calculation controls the damping effect of the gripping toe (3), and the buffering and damping capacity of the gripping toe (3) is changed. When the flexible foot end is not stressed, the upper half of the corrugated pipe ankle is in a non-compressed state, at this time the contact surface between the upper end of the corrugated pipe ankle and the body is the 0 reference point; when the flexible gripping foot end is stressed, the downward compression movement direction of the flexible gripping foot end is positive; then when the upper and lower parts of the flexible foot end are gas volumes: According to the ideal gas polytropic equation: For the gas pressure P of the mixed gas, equation (2) is written as: V ankle = V ankle0 -sx V toe = V toe0 + f(P toe ) (1) wherein V ankle , V toe are the real-time internal gas volume of the flexible gripping foot end ankle and toe, respectively; V ankle0 , V toe0 are the initial internal gas volume of the ankle and toe when the flexible gripping foot end is not compressed; s is the effective cross-sectional area of the ankle part of the flexible gripping foot end; x is the stress compression displacement of the ankle part of the flexible gripping foot end; f(P toe ) is the expansion volume of the toe part of the flexible gripping foot end under the enhancement of air pressure; f(P toe ) is the slight change in the volume of the flexible toe (3) part caused by the change in the air pressure, which is ignored due to its small influence on the overall gas volume change. Combined with formula (1) and formula (3), the gas pressure change of the upper and lower parts of the gripping foot end satisfies: PV = nrT emp (2) where P is the gas pressure, V is the gas volume, n is the amount of substance of the gas, r is the gas constant, T is the temperature emp is the system temperature; According to the compressibility of air and the continuity of air mass flow, the relationship between the gas mass in the flexible ankle air chamber and the gas pressure and volume change is: PV air = n air rT emp (3) where V air is the volume of the gas in the ideal gas equation, n air is the amount of air substance in the container; The gas mass flow in the flexible ankle part damping hole is: wherein P ankle , P toe are the real-time internal gas pressure of the flexible gripping foot end ankle and toe, respectively, P ankle0 , P toe0 are the gas pressure values of the ankle and toe parts in the initial state, respectively; n change is the amount of substance of the gas flowing from the ankle to the toe inside, n ankle is the amount of substance of the original gas in the ankle inside, n toe is the amount of substance of the original gas in the toe inside; Wherein, ρ0 is the gas density in the initial state; where G z is the gas mass flow rate of the flexible foot end interior ankle portion, is the ankle gas pressure rate of change; is the ankle interior gas volume rate of change; T ankle0 is the ankle system temperature at the initial state; The transient change rate of the internal air pressure of the flexible ankle part is written as: wherein ξ toe is the local resistance coefficient of the sudden contraction of the flow stream through the orifice, p is the gas density at the flexible foot end; g is the acceleration due to gravity, a ankle is the flow coefficient of the flow through the contraction section at the ankle of the damper orifice, a toe is the flow coefficient of the flow through the contraction section at the toe of the damper orifice, is the square of the gas flow velocity at the contraction section at the ankle, is the square of the gas flow velocity at the contraction section at the toe. According to the uniform distribution of flow velocity on the contraction section of the small hole, a ankle = 1, a toe = 1; thus In the formula, C v is the orifice velocity coefficient, Δp is the pressure difference at the foot and ankle, and a is the area of the smallest cross-sectional flow area c The ratio of the orifice cross-sectional flow area a to the orifice velocity coefficient C is c Then a c = C c a, and the flow formula of the short-hole damping hole is obtained as where q c is the flow through the short orifice, C q is the orifice flow coefficient; C c is the area a c is the ratio of the orifice flow area a c is the flow velocity at the minimum flow area, a The transient change rate of the internal air pressure of the toe is: The non-linear stiffness expression of the ankle part is: The gripping toe (3) flexible embedded base (4), the upper half of the connecting joint (2) is connected with the passive compression component (1), and a groove is arranged at the connecting position, which is used for fixing the passive compression component (1). The interface of the connecting joint (2) for fixing the gripping toe (3) is provided with a plurality of convex interfaces composed of mortise and tenon structure, which are used for fixing and positioning the position of the gripping toe (3); a plurality of convex interfaces are uniformly arranged around the circumference of the connecting joint (2). wherein is the rate of change of the internal air pressure of the toe of the flexible foot; T toe0 and V toe are the initial temperature of the gas in the toe of the flexible foot and the real-time volume of the gas cavity of the toe of the flexible foot, respectively; The middle of the connecting joint (2) is connected with the air passage, the size of the air hole in the air passage is proportionally set with the length of the air hole, and the size of the air hole obtained by calculation controls the damping size of the foot end of the gripping toe (3). where K is a nonlinear stiffness, is the rate of change of force, is the velocity, is the rate of change of ankle air pressure, A is the effective cross-sectional area of the ankle.

2. The corrugated tube based gravity self-driven robot flexible foot end structure according to claim 1, wherein, The gripping toe (3) is internally provided with a plurality of interconnected air chambers; 3. The corrugated tube based gravity self-driven robot flexible foot end structure according to claim 2, characterized in that, The passive compression component (1) is connected with the gripping toe (3) through the connecting joint (2), the middle of the connecting joint (2) is connected with the air passage, the size of the air hole in the air passage is proportionally set with the length of the air hole, and the size of the air hole obtained by calculation controls the damping effect of the gripping toe (3), and the buffering and damping capacity of the gripping toe (3) is changed.

4. The corrugated tube based gravity self-driven robot flexible foot end structure according to claim 3, characterized in that, ​ 5. The corrugated tube based gravity self-driven robot flexible foot end structure according to claim 1, wherein, ​ The ground-gripping toes (3) are multiple, and the sizes of the ground-gripping toes (3) gradually decrease from the toe heel to the toe tip; a toe ground-contacting rubber surface (5) is further arranged at the bottom of the ground-gripping toes (3).

6. The corrugated tube based gravity self-driven robot flexible foot end structure according to claim 2, wherein, The base (4) is connected with the ground-gripping toes (3) through the embedded groove.

7. The corrugated tube based gravity self-driven robot flexible foot end structure according to claim 1, wherein, The passive compression component (1) adopts a U-shaped bellows structure, and the height-width ratio of the passive compression component (1) ranges from 0.5 to 1.5.

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