Self-adaptive variable-stiffness sole based on tensegrity structure and control method of self-adaptive variable-stiffness sole

Abstract

The invention relates to a self-adaptive variable-rigidity sole based on a tensegrity structure and a control method thereof.The self-adaptive variable-rigidity sole comprises a tensegrity ankle joint which is used for being fixedly connected with the foot end of a quadruped robot and can achieve inward turning, outward turning, plantar flexion and dorsiflexion movement, and a self-adaptive variable-rigidity tensegrity sole part is installed on the lower side of the tensegrity ankle joint; and a silica gel sole is arranged at the bottom of the tensioning sole part. The self-adaptive variable-stiffness sole can adapt to and envelop a plurality of non-structural terrains, and the terrain trafficability of the foot type robot is enhanced.

Description

Technical Field

[0001] The invention relates to a foot structure of a footed robot, and in particular to an adaptive variable-rigidity sole based on a tensegrity structure and a control method thereof. Background Art

[0002] The existing mobile mechanisms are mainly foot-type, wheel-type, and track-type. Compared with other mobile modes, foot-type walking mechanisms have their own unique and irreplaceable role. Because the movement trajectory of foot-type walking mechanisms is mostly discrete points, they can pass through complex road conditions and have strong adaptability to different terrain environments.

[0003] Legged robots have greater degrees of freedom due to the advantages of their leg-foot structure, and can achieve better terrain adaptation than wheeled robots. However, quadrupedal robots rely on existing foot structures and have great limitations when stepping on unstructured terrain such as pipelines. Feet are the result of long-term evolution of humans and animals. They are in direct contact with the ground during walking and play a vital role in adaptive walking. In addition, when organisms come into contact with media of different hardness and softness, they will adjust the stiffness of the soles of the feet through muscle movement according to the ground conditions. On hard ground, the soles of the feet become softer to reduce impact force; on soft media, the soles of the feet become harder to improve the distribution of force in order to adapt to different media environments. Therefore, we focus on the foot structure.

[0004] During the movement of the quadruped robot, the rapid switching between the leg support phase and the swing phase and the external impact force will cause unstable disturbances to the quadruped robot. These disturbance factors will cause the position of the foothold of the quadruped robot to deviate. These position deviations will also cause the landing time of the two legs in the swing phase to be inconsistent. The inconsistent landing time will cause the side that lands first to give the other side a capsizing torque, and at the same time increase the contact impact force between the foot end and the ground, causing the quadruped robot to become unstable and even eventually overturn. In order to avoid this phenomenon, we can use the characteristics of the adaptive tension foot, combined with the adjustment of the foothold position, to achieve stable adaptive movement on unstructured ground. On the basis of this structure, in order to further improve the terrain adaptability of the quadruped robot. Summary of the invention

[0005] The purpose of the present invention is to provide an adaptive variable stiffness sole based on a tensegrity structure and a control method thereof, wherein the adaptive variable stiffness sole can adapt to and envelop many non-structural terrains, thereby enhancing the terrain passability of a foot-type robot.

[0006] The technical solution of the present invention is: an adaptive variable stiffness sole based on a tensegrity structure, including a tensegrity ankle joint fixedly connected to the foot end of a quadruped robot and capable of realizing inversion, eversion, plantar flexion and dorsiflexion movements, a tensegrity palm with adaptive variable stiffness installed on the lower side of the tensegrity ankle joint, and a silicone sole provided on the bottom of the tensegrity palm.

[0007] Furthermore, the tensioning ankle joint includes a support seat frame, a support column is vertically fixed on the support seat frame, a fixed seat frame connected to the foot end of the quadruped robot is sleeved on the support column, eight high-rigidity springs connected to the bottom of the fixed seat frame are symmetrically distributed in a star shape around the upper end of the support column, and a pair of low-rigidity springs connected to the support bottom frame are obliquely arranged on both sides of the bottom of the fixed seat frame.

[0008] Furthermore, a flange is provided at the upper end of the support column, and a pair of first spring fasteners for connecting to one end of a high-rigidity spring are provided at the four corners of the flange, and a second spring fastener for connecting to the other ends of two adjacent high-rigidity springs is provided at the middle of each side edge of the bottom of the fixed seat frame, so that the two adjacent high-rigidity springs cooperate to form a V-shape.

[0009] Furthermore, third spring fasteners connected to one end of the low-rigidity spring are installed on the front and rear parts of both side edges of the bottom of the fixed seat frame, and a pair of fourth spring fasteners connected to the other end of the low-rigidity spring are respectively arranged on both sides of the supporting seat frame.

[0010] Furthermore, the tensioning palm portion includes a support rod, and the front and rear portions of the support base frame are respectively rotatably connected with a pair of support rods located on both sides, and four pairs of X-shaped unit assemblies hinged in sequence along the transverse direction are rotatably connected between the lower ends of the two pairs of support rods, and the upper and lower portions of the X-shaped unit assemblies are respectively connected with a pair of transverse springs, and the upper and lower portions of the two groups of X-shaped unit assemblies located in the middle are connected to one end of a transversely arranged variable stiffness spring, and the other ends of the variable stiffness springs are respectively connected to a driving mechanism installed on the support base frame via ropes.

[0011] Furthermore, five pairs of longitudinal unit shafts arranged up and down are evenly distributed along the transverse direction between the two pairs of support rods, and the ends of each pair of longitudinal unit shafts are connected via sealing covers; between two adjacent pairs of longitudinal unit shafts, the longitudinal unit shaft located at the upper front part is rotatably connected to one end of the first oblique rod, and the other end of the first oblique rod is rotatably connected to the longitudinal unit shaft located at the lower rear part, the longitudinal unit shaft located at the lower front part is rotatably connected to one end of the second oblique rod, and the other end of the second oblique rod is rotatably connected to the longitudinal unit shaft at the upper rear part, and the inclination direction of the second oblique rod is opposite to that of the first oblique rod and forms an X shape with the projection of the first oblique rod in the longitudinal direction.

[0012] Furthermore, the sealing cover at the head end and the sealing cover at the end are both rotatably connected to the lower ends of the corresponding support rods via longitudinal pins; a spring connection portion is provided on the longitudinal unidirectional shaft, and the transverse spring is provided between two adjacent longitudinal unit shafts located in the same horizontal plane.

[0013] Furthermore, the driving mechanism includes a steering gear installed on the supporting base frame, and a steering wheel is installed on the output shaft of the steering gear; one end of the variable stiffness spring is connected to the longitudinal unit shaft located in the middle; among the two variable stiffness springs on the same longitudinal unit shaft, the rope connected to the other end of one variable stiffness spring passes through the longitudinal unit shaft located at the frontmost side and is connected to the front of the steering wheel via a guide installed at the lower front part of the supporting base frame, and the rope connected to the other end of the other variable stiffness spring passes through the longitudinal unit shaft located at the rearmost side and is connected to the rear of the steering wheel via a guide installed at the lower rear part of the supporting base frame.

[0014] Furthermore, the silicone sole is made of silicone with a hardness of 5 degrees and completely covers the bottom surface of the tensioned palm, and the silicone sole is bonded to the bottom surface of the tensioned palm by glue.

[0015] A control method for an adaptive variable stiffness sole based on a tensegrity structure is as follows: (1) Using the quadruped robot’s own feedback information, the gait trajectory is adjusted and the foot position of the quadruped robot is adjusted and compensated; (2) According to the terrain medium information fed back by the quadruped robot's visual system, the stiffness of the tension palm is adjusted to match different media, thereby improving the quadruped robot's terrain adaptability; (3) After the quadruped robot completes the envelope adaptation to the protrusion, the palm stiffness is increased to enhance the gripping force and achieve low-stiffness landing.

[0016] Compared with the prior art, the present invention has the following advantages: 1. The adaptive variable stiffness sole has high adaptability, variable stiffness and certain stable support. With flexible ankle joints and adaptive, variable stiffness soles, it can adapt to many non-structural terrains. Variable stiffness can improve gripping power and match terrains of different stiffness to improve the terrain adaptability of the foot-type robot, enhance the terrain passability of the foot-type robot, and enable the foot-type robot to adapt to more complex terrains.

[0017] 2. It enables the quadruped robot to walk adaptively in unstructured terrain and enhances its ability to crawl on steep slopes. Compared with other foot structures, it improves the stability and motion performance of the quadruped robot. In addition, the quadruped robot can combine visual information with control methods to change the stiffness of the sole, thereby matching media with different stiffness and enhancing the ability to adapt to terrain. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the overall structure of the adaptive variable stiffness tension foot and the quadruped robot of the present invention; Figure 2 The schematic diagram of the adaptive variable stiffness tension foot structure of the present invention is shown in FIG. Figure 1 ; Figure 3 The schematic diagram of the adaptive variable stiffness tension foot structure of the present invention is shown in FIG. Figure 2 ; Figure 4 It is a schematic diagram of the structure of the adaptive variable stiffness tension foot after the fixed seat frame is truncated according to the present invention; Figure 5 This is a diagram of the tension palm structure of the present invention; Figure 6 A comparison diagram of the tension foot and the rigid foot of the present invention; Figure 7 It is a simplified structural diagram of the tensioning foot of the present invention; Figure 8 It is the control strategy flow chart of the present invention; In the figure: 1-quadruped robot; 2-silicone sole; 100-tension ankle joint; 101-high stiffness spring; 120-low stiffness spring; 110-support seat frame; 111-fourth spring fastener; 112-guide; 120-support column; 121-flange; 122-first spring fastener; 130-fixed seat frame; 131-second spring fastener; 132-third spring fastener; 200-tension palm; 201-support rod; 202-lateral spring; 203-variable stiffness spring; 204-longitudinal unit shaft; 205-sealing cover; 206-first diagonal rod; 207-longitudinal pin; 208-spring connecting part; 209-avoidance groove; 210-servo; 211-steering plate; 212-second diagonal rod; 220-rope. DETAILED DESCRIPTION

[0019] In order to make the above features and advantages of the present invention more easily understood, embodiments are given below with reference to the accompanying drawings for detailed description, but the present invention is not limited thereto.

[0020] refer to Figures 1 to 8 A self-adaptive variable-rigidity sole based on a tensegrity structure, comprising a tensegrity ankle joint 100 for fixed connection with the foot end of a quadruped robot 1 and capable of achieving inversion, eversion, plantar flexion and dorsiflexion movements; a self-adaptive variable-rigidity tensegrity palm 200 is installed on the lower side of the tensegrity ankle joint, which has the characteristics of deformability, self-recovery and variable stiffness; a silicone sole 2 is provided at the bottom of the tensegrity palm.

[0021] In this embodiment, the tension ankle joint includes a support seat frame 110, on which a support column 120 is vertically fixed, and a fixed seat frame 130 connected to the foot end of the quadruped robot is sleeved on the support column. Eight high-rigidity springs 101 connected to the bottom of the fixed seat frame are symmetrically distributed in a star shape around the upper end of the support column, which are the main load-bearing springs in the ankle joint; a pair of low-rigidity springs 102 connected to the support bottom frame are obliquely arranged on both sides of the bottom of the fixed seat frame, a total of four and symmetrically distributed. The high-rigidity springs and the low-rigidity springs form a complete tension network. Through the rigid structure similar to biological bones and the flexible spring similar to the ligament structure, the tension ankle joint has the flexibility of the human ankle joint, can complete plantar flexion, dorsiflexion, inversion, eversion and other actions, and keep the upper end of the ankle and foot in a horizontal state, which does not change with the terrain, and may play a role in improving stability on non-structural ground like an inclined plane.

[0022] In this embodiment, the ratio of the stiffness of the high-stiffness spring to the stiffness of the low-stiffness spring is >10.

[0023] In this embodiment, in order to better install the high-rigidity spring, a flange 121 is provided at the upper end of the support column, and a pair of first spring fasteners 122 for connecting to one end of the high-rigidity spring are provided at the four corners of the flange. A second spring fastener 131 for connecting to the other ends of two adjacent high-rigidity springs is provided in the middle of each side edge of the bottom of the fixed seat frame, and the two adjacent high-rigidity springs cooperate to form a V shape.

[0024] In this embodiment, in order to connect the supporting seat frame with the fixed seat frame, third spring fasteners 132 connected to one end of the low-rigidity spring are installed on the front and rear parts of both side edges of the bottom of the fixed seat frame, and a pair of fourth spring fasteners 111 connected to the other end of the low-rigidity spring are respectively provided on both sides of the supporting seat frame.

[0025] In this embodiment, the overall size of the tensioning palm is 100mm long and 48mm wide. The tensioning palm includes a support rod 201, and the front and rear parts of the support bottom frame are respectively rotatably connected with a pair of support rods located at the two side parts, and the rotation pair located between the lower ends of the two pairs of support rods is rotatably connected with four pairs of X-shaped unit components hinged in sequence along the transverse direction; the X-shaped unit components are deformable, and the upper and lower parts of the X-shaped unit components are respectively connected with a pair of transverse springs 202, which are recoverable under the elasticity of the transverse springs; the upper and lower parts of the two groups of X-shaped unit components in the middle are connected to one end of a transversely arranged variable stiffness spring 203, and the other end of the variable stiffness spring is respectively connected to the driving mechanism installed on the support bottom frame through a rope 220, so as to control the stiffness of the tensioning palm.

[0026] In this embodiment, five pairs of longitudinal unit shafts 204 arranged vertically and evenly distributed in the horizontal direction between two pairs of supporting rods are arranged, and the ends of each pair of longitudinal unit shafts are connected via a sealing cover 205; between two adjacent pairs of longitudinal unit shafts, the longitudinal unit shaft located at the upper part of the front side is rotatably connected to one end of the first inclined rod 206, and the other end of the first inclined rod is rotatably connected to the longitudinal unit shaft located at the lower part of the rear side, and the longitudinal unit shaft located at the lower part of the front side is rotatably connected to one end of the second inclined rod 212, and the other end of the second inclined rod is rotatably connected to the longitudinal unit shaft at the upper part of the rear side, and the inclination direction of the second inclined rod is opposite to that of the first inclined rod and forms an X-shape with the projection of the first inclined rod in the longitudinal direction. Thus, the structures between two adjacent pairs of longitudinal unit shafts cooperate to form an X-shaped unit assembly, and the five pairs of longitudinal unit shafts cooperate to form four groups of X-shaped unit assemblies.

[0027] Since the tension palm is connected to the main part by a supporting rod through a rotating pair, the size of the variable stiffness sole can change, thereby increasing the deformation degree of the tension palm. In addition, the change in the stiffness of the tension palm can enhance the gripping force on irregular objects, match terrain media with different stiffness, and further enhance stability and terrain adaptability.

[0028] In this embodiment, the sealing cover at the head end and the sealing cover at the end are both rotatably connected to the lower end of the corresponding support rod via the longitudinal pin shaft 207; the longitudinal one-way shaft is provided with a spring connection part 208, the transverse spring is provided between two adjacent longitudinal unit shafts located in the same horizontal plane, and the two ends are respectively connected to the spring connection part. The longitudinal one-way shaft is radially provided with an avoidance groove 209 for the variable stiffness spring to pass through.

[0029] In this embodiment, the driving mechanism includes a steering gear 210 installed on the supporting bottom frame, and a steering disc 211 is installed on the output shaft of the steering gear; one end of each of the variable stiffness springs is connected to the longitudinal unit shaft located in the middle; of the two variable stiffness springs on the same longitudinal unit shaft, the rope connected to the other end of one variable stiffness spring bypasses the longitudinal unit shaft located at the frontmost side and is connected to the front part of the steering disc through the guide 112 installed at the lower front part of the supporting bottom frame, and the rope connected to the other end of the other variable stiffness spring bypasses the longitudinal unit shaft located at the rearmost side and is connected to the rear part of the steering disc through the guide 112 installed at the lower rear part of the supporting bottom frame. Thus, the preload on the spring is changed by the steering gear, and the adaptive and variable stiffness foot sole is realized by relying on the characteristics of these two points.

[0030] In this embodiment, the guide member may include a reversing guide wheel and a guide shaft.

[0031] In this embodiment, the silicone sole is made of solidified silicone with a hardness of 5 degrees, and the size is consistent with the sole of the foot, completely covering the bottom surface of the tensioned palm part, and the silicone sole surface is rectangular and glued to the contact point between the bottom surface of the tensioned palm part and the ground. The silicone bottom surface group is responsible for isolating mud, sand and gravel to prevent them from jamming the spring and affecting the normal use of the sole of the foot. The silicone bottom surface changes passively with the change of the X-shaped sole of the foot.

[0032] When the sole of the foot encounters flat terrain, the direction of the plantar force on the sole of the foot is consistent, and the sole of the foot remains stable; when the sole of the foot steps on irregular ground, the direction of the plantar force caused by the ground on each contact point on the sole of the foot is inconsistent, resulting in the deformation of the X-shaped unit of the sole substructure, until the sole of the foot and the ground are adapted to the maximum extent, and the plantar force is perpendicular to the contact point of the X-shaped unit to achieve stability, and thereby obtain a larger support area, and achieve reinforcement by increasing stiffness. This process is similar to the envelope grasping of a flexible gripper. The sole envelope is "fixed" on the protrusion to reduce the possibility of slippage, so it may be possible to improve the terrain adaptability; and achieve self-recovery when the foot is lifted. Due to this feature, the tensioned palm is as close to the ground as possible, keeping the plantar force colinear with the robot's gravity, and maintaining a balanced state, which can improve the terrain adaptability. This process is similar to the envelope grasping of a flexible gripper. The sole envelope is "fixed" on the protrusion to reduce the possibility of slippage, so it may be possible to improve the terrain adaptability; and achieve self-recovery when the foot is lifted. Due to this feature, the tensioned palm is as close to the ground as possible, keeping the plantar force combined with the robot's gravity in line, and maintaining a balanced state, which can improve the terrain adaptability.

[0033] like Figure 6 As shown, when the sole of the foot of the present application encounters the two types of unstructured terrain in the figure, it will achieve envelope adaptation to the terrain, provide a better contact area, and prevent point slip and sliding caused by a small force-bearing area. However, the rigid foot and the ball foot complete the entire contact process when encountering a protruding contact point, which will result in only one or two contact positions as shown in the figure, resulting in a sharp decrease in the force-bearing area between the sole of the foot and the irregular ground. This situation increases the possibility of slippage and may even cause the robot to tip over or roll over.

[0034] The structural diagram of the variable stiffness tension foot is as follows: Figure 7 As shown, the sole of the foot is analyzed for stiffness by combining two X-shaped units. The black ones in the figure are rigid rods, the red ones are basic springs that maintain the stability of the tensegrity structure, and the blue ones are variable stiffness springs. Represents the coordinates of each spring node. The specific spring node coordinates are shown in Table 1.

[0035] In order to establish the stiffness model of the tensegrity foot, the stiffness of the generalized tensegrity structure can be listed first: (1) In the formula k i , τi and l i ──No. i The stiffness, elasticity and length of the ropes; ──No. i The unit vector of the rope; ──Vector The antisymmetric matrix of .

[0036] The Jacobian matrix J transforms the joint coordinates Mapped to rope length changes: (2) In the formula, the Jacobian matrix corresponding to the i-th rope is defined as .

[0037] Table 1 Variable stiffness foot spring node coordinate parameter table: .

[0038] Substituting equation (2) into equation (1), we can get the stiffness matrix: (3) In the formula, ——Translational stiffness of the tension joint, ; ——Symmetrical stiffness, ; ——coupling stiffness of joints, ; ——Rotational stiffness of the joint, .

[0039] because , then we can get the antisymmetric matrix : (4).

[0040] right Figure 7 From the structure in the above example, we can see from formula (3) that the stiffness is mainly divided into four parts, namely, four 3X3 matrices. Since the X-type unit only rotates on the Z axis, we only focus on the rotation stiffness on the Z axis, that is, we only focus on the stiffness in formula (3). The third term of , so the stiffness of the sole of the foot can be obtained The expression is shown in 3-31. (5).

[0041] Combining formula (5) and formula (3), we can see that changing the preload force τ on the spring i This will change the overall stiffness.

[0042] The control method of the adaptive variable stiffness sole based on the tensegrity structure is as follows: (1) Using the feedback information from the quadruped robot itself, the robot collects and analyzes road information, locates irregular protrusions and medium stiffness, processes the information, adjusts the gait trajectory, calculates the landing point of the quadruped robot, and makes adjustments and compensations; (2) According to the terrain medium information fed back by the quadruped robot's visual system, the stiffness of the tension palm is adjusted to match different media, such as adapting to soft media, thereby improving the quadruped robot's terrain adaptability; (3) After the quadruped robot completes the envelope adaptation to the protrusion, the palm stiffness is increased to enhance the gripping force, and the control strategy of low-stiffness landing adaptation and high-stiffness reinforcement is adopted to enhance the stability of the movement process. The flow chart is as follows Figure 8 shown.

[0043] The above is only a preferred embodiment of the present invention. For ordinary technicians in this field, according to the teachings of the present invention, designing different forms of adaptive variable stiffness feet based on tensegrity structures and control methods thereof does not require creative labor. Without departing from the principles and spirit of the present invention, all equal changes, modifications, substitutions and variations made within the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. An adaptive variable stiffness sole based on tensegrity structure, characterized in that: The invention comprises a tensioning ankle joint for being fixedly connected to the foot end of a quadruped robot and capable of realizing inversion, eversion, plantar flexion and dorsiflexion movements. The lower side of the tensioning ankle joint is installed with a tensioning palm part with adaptive variable stiffness, and the bottom of the tensioning palm part is provided with a silicone sole.

2. The adaptive variable stiffness foot sole based on tensegrity structure and control method thereof according to claim 1, characterized in that: The tensioning ankle joint includes a support seat frame, a support column is vertically fixed on the support seat frame, and a fixed seat frame connected to the foot end of the quadruped robot is sleeved on the support column. Eight high-rigidity springs connected to the bottom of the fixed seat frame are symmetrically distributed in a star shape around the upper end of the support column, and a pair of low-rigidity springs connected to the support bottom frame are obliquely arranged on both sides of the bottom of the fixed seat frame.

3. The adaptive variable stiffness sole based on tensegrity structure and control method thereof according to claim 2, characterized in that: A flange is provided at the upper end of the support column, and a pair of first spring fasteners for connecting to one end of a high-rigidity spring are provided at the four corners of the flange. A second spring fastener for connecting to the other ends of two adjacent high-rigidity springs is provided in the middle of each side edge of the bottom of the fixed seat frame, and the two adjacent high-rigidity springs cooperate to form a V shape.

4. The adaptive variable stiffness foot sole based on tensegrity structure and control method thereof according to claim 2 or 3, characterized in that: The front and rear parts of both sides of the bottom of the fixed seat frame are installed with third spring fasteners connected to one end of the low-rigidity spring, and the two sides of the supporting seat frame are respectively provided with a pair of fourth spring fasteners connected to the other end of the low-rigidity spring.

5. The adaptive variable stiffness foot sole based on tensegrity structure and control method thereof according to claim 1, 2 or 3, characterized in that: The tensioning palm includes a support rod, and the front and rear parts of the support base frame are respectively rotatably connected to a pair of support rods located on both sides, and four pairs of X-shaped unit assemblies hinged in sequence along the transverse direction are rotatably connected between the lower ends of the two pairs of support rods. The upper and lower parts of the X-shaped unit assemblies are respectively connected to a pair of transverse springs, and the upper and lower parts of the two groups of X-shaped unit assemblies located in the middle are connected to one end of a transversely arranged variable stiffness spring, and the other ends of the variable stiffness springs are respectively connected to the driving mechanism installed on the support base frame via ropes.

6. The adaptive variable stiffness sole based on tensegrity structure and control method thereof according to claim 5, characterized in that: Five pairs of longitudinal unit shafts are evenly distributed horizontally between the two pairs of support rods, and the ends of each pair of longitudinal unit shafts are connected via sealing covers; between two adjacent pairs of longitudinal unit shafts, the longitudinal unit shaft located at the upper front part is rotatably connected to one end of the first oblique rod, and the other end of the first oblique rod is rotatably connected to the longitudinal unit shaft located at the lower rear part, the longitudinal unit shaft located at the lower front part is rotatably connected to one end of the second oblique rod, and the other end of the second oblique rod is rotatably connected to the longitudinal unit shaft at the upper rear part, and the inclination direction of the second oblique rod is opposite to that of the first oblique rod and forms an X shape with the projection of the first oblique rod in the longitudinal direction.

7. The adaptive variable stiffness sole based on tensegrity structure and control method thereof according to claim 6, characterized in that: The sealing cover at the head end and the sealing cover at the tail end are both rotatably connected to the lower ends of the corresponding support rods via longitudinal pins; a spring connection portion is provided on the longitudinal unidirectional shaft, and the transverse spring is provided between two adjacent longitudinal unit shafts located on the same horizontal plane.

8. The adaptive variable stiffness foot sole based on tensegrity structure and control method thereof according to claim 6 or 7, characterized in that: The driving mechanism includes a steering gear installed on the supporting base frame, and a steering wheel is installed on the output shaft of the steering gear; one end of each of the variable stiffness springs is connected to the longitudinal unit shaft located in the middle; among the two variable stiffness springs on the same longitudinal unit shaft, the rope connected to the other end of one of the variable stiffness springs passes around the longitudinal unit shaft located at the frontmost side and is connected to the front of the steering wheel through a guide installed at the lower front part of the supporting base frame, and the rope connected to the other end of the other variable stiffness spring passes around the longitudinal unit shaft located at the rearmost side and is connected to the rear of the steering wheel through a guide installed at the lower rear part of the supporting base frame.

9. The adaptive variable stiffness sole based on tensegrity structure and control method thereof according to claim 5, characterized in that: The silicone sole is made of silicone with a hardness of 5 degrees and completely covers the bottom surface of the tensioned palm. The silicone sole is bonded to the bottom surface of the tensioned palm by glue.

10. A control method for an adaptive variable stiffness sole based on a tensegrity structure as claimed in claim 1, 2, 3, 6, 7 or 9, characterized in that: Here’s how: (1) Using the quadruped robot’s own feedback information, the gait trajectory is adjusted and the foot position of the quadruped robot is adjusted and compensated; (2) Based on the terrain medium information fed back by the quadruped robot's visual system, the stiffness of the tensioning palm is adjusted to match different media, thereby improving the quadruped robot's terrain adaptability; (3) After the quadruped robot completes the envelope adaptation to the protrusion, the palm stiffness is increased to enhance the gripping force and achieve low-stiffness landing.

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