A stability criterion method for quadruped robots based on critical stability margin

Abstract

The present invention provides a stability criterion method for a quadruped robot based on a critical stability margin, the method comprising: 1) calibrating the quadruped robot data in a stationary standing state to obtain parameters of the quadruped robot in a stationary standing state; 2) constructing a first-order stability margin of the robot according to the parameters; 3) obtaining information of the quadruped robot during movement according to sensor data; 4) constructing a critical stability margin during the robot movement process according to the information, and constructing a hierarchical stability margin through a captureable area theory, repeating steps 3 and 4, and then continuously determining the stability state; the method constructs a critical stability margin to perform stability criterion for the quadruped robot, takes the robot's movement speed and the corresponding capture point position as stability criterion indicators, can consider the influence of the robot's location terrain and the moving speed factor, and provides a broader basis for the stability criterion of the quadruped robot.

Description

Technical Field

[0001] The invention relates to the technical field of legged robots, and in particular to a stability criterion method for a quadruped robot based on a critical stability margin. Background Art

[0002] Compared with wheeled and tracked ground mobile robots, legged robots have great advantages in terrain crossing due to their unique floating base dynamic characteristics. Compared with bipedal robots, quadrupedal robots have stronger stability and stronger maneuverability than hexapod robots. Due to their characteristics, quadrupedal robots can be used for disaster relief, material transportation, mobile reconnaissance, strategic assault, etc., but it is often difficult to balance the stability and high maneuverability of quadrupedal robots.

[0003] The stability criterion method is one of the fundamental problems that limit the high mobility of quadruped robots. Because legged motion is a nonlinear, strongly coupled and high-dimensional motion mode, the existing stability criterion and control methods are still unclear about the essence of legged stability criterion, and there is no unified general simplified model and stability criterion method. The more widely used stability criterion methods for quadruped robots are the ground reference point method and the leg simplified model method. The former generally constructs a ground reference point with physical meaning according to the force condition of the quadruped robot, while the latter generally simplifies the leg model by ignoring the mass and structure of the leg, and then constructs the dynamics of the simplified model. However, the ground reference point method only considers the force condition, not the current speed of the robot; the leg simplified model method only considers the simplified dynamics under ideal conditions, and does not consider the terrain.

[0004] In summary, the stability criteria of quadruped robots currently have poor applicability, poor maneuverability and do not consider the robot's moving speed. Summary of the invention

[0005] Aiming at the problems of poor applicability and mobility of existing quadruped robot stability criterion methods and failure to consider the robot's moving speed, a quadruped robot stability criterion method based on critical stability margin is proposed. This method combines the simplified virtual legs of the quadruped robot with the linear inverted pendulum capture area and ESM energy stability margin to construct critical stability margins of different levels, and takes the robot's movement speed and the corresponding capture point position as stability criterion indicators.

[0006] The present invention proposes a stability criterion method for a quadruped robot based on a critical stability margin, comprising the following steps:

[0007] Step 1, calibrating the quadruped robot data in a stationary standing state to obtain parameters of the quadruped robot in a stationary standing state; the parameters include a body length 2a, a body width 2b, and a height Z of the body mass center from the ground;

[0008] Step 2, constructing the first-order critical stability margin of the robot according to the parameters obtained in step 1;

[0009] Step 3, obtaining information of the quadruped robot in real time during the movement according to the sensor; the information includes the center of mass position P, speed Acceleration and leg posture;

[0010] Step 4: construct the hierarchical stability margin through the first-order critical stability margin constructed in step 2 and the information obtained in step 3 and make a judgment to obtain the stability state of the current quadruped robot. Repeat steps 3 and 4 to continuously judge the stability state.

[0011] As a preferred solution of the present invention, the first-order stability margin of the robot constructed in step 2 is specifically:

[0012] Assuming that the friction coefficient of the ground is infinite, the kinetic energy of the motion state of the quadruped robot is equivalent to the overturning potential energy required along the support boundary or the direction of the supporting leg. The relationship between the first-order stability margin boundary and the ESM energy stability margin is derived. The two diagonal legs of the quadruped robot are simplified into a virtual leg, and the virtual leg support point is taken as the origin, and the polar axis direction is horizontally forward to establish a polar coordinate representation:

[0013]

[0014]

[0015]

[0016]

[0017]

[0018] Where θ is the angle between the velocity direction of the center of mass and the polar axis, in the first quadrant of the rectangular coordinate system: P margin 1 is the boundary equation of the first-order stability margin at rest; x is the coordinate in the polar axis direction, y is the coordinate in the horizontal plane perpendicular to the polar axis direction, ρ body is the fuselage geometry constraint, is the first-order critical speed.

[0019] As a preferred solution of the present invention, the step 4 of constructing the hierarchical stability margin is specifically as follows:

[0020] The critical stability margin is constructed by converting the corresponding energy into the capture point position, and the corresponding step-by-step stability margin reference diagram is plotted by polar coordinates;

[0021] Among them, the first-order critical stability margin is:

[0022]

[0023] The second-order critical stability margin is constructed based on the first-order critical stability margin with one more step to capture the position l:

[0024]

[0025] The third-order critical stability margin is constructed based on the first-order critical stability margin plus the maximum capture area:

[0026]

[0027] Among them, ρ body is the body geometry constraint, the capture position l is determined by the step length of the quadruped robot, and Δt is the time required for the quadruped robot to take a step.

[0028] As a preferred embodiment of the present invention, in step 4, the determination of the stability state of the current quadruped robot includes determining the velocity of the center of mass of the quadruped robot and determining the stability margin interval.

[0029] As a preferred solution of the present invention, the quadruped robot mass center velocity determination is specifically as follows: based on constructing a hierarchical stability margin, a corresponding critical velocity is calculated, and the current quadruped robot mass center velocity is determined to obtain the current stability state of the quadruped robot;

[0030] Among them, the first-order critical speed is:

[0031]

[0032] When the current center-of-mass velocity of the quadruped robot is less than the first-order critical velocity, the quadruped robot does not need to make corresponding adjustments to reach a stable state;

[0033] The second-order critical speed is:

[0034]

[0035] When the current center-of-mass velocity of the quadruped robot is between the first-order critical velocity and the second-order critical velocity, the quadruped robot needs to take a step immediately in the direction of the center-of-mass velocity to stabilize;

[0036] The third-order critical speed is:

[0037]

[0038] When the center-of-mass velocity of the current quadruped robot is between the second-order critical velocity and the third-order critical velocity, the quadruped robot needs to continue moving in the direction of the center-of-mass velocity to stabilize.

[0039] As a preferred solution of the present invention, the stability margin interval determination of the quadruped robot is specifically as follows: the stability margin interval where the current quadruped robot state is located is determined by drawing a corresponding step-by-step stability margin reference diagram using polar coordinates:

[0040] If the capture point position corresponding to the current center of mass velocity is within the first-order stability margin, the quadruped robot does not need to make corresponding adjustments even if it is in a stable state;

[0041] If the capture point position corresponding to the current center of mass velocity is between the first-order stability margin and the second-order stability margin, the quadruped robot only needs to take a step in the direction of the center of mass velocity immediately to stabilize;

[0042] If the capture point position corresponding to the current center of mass velocity is between the second-order stability margin and the third-order stability margin, the quadruped robot needs to continue moving in the direction of the center of mass velocity to achieve stability.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] 1) Because the present invention adopts the ESM energy stability margin, it overcomes the problem that the stability criterion method in the prior art does not consider the stability influence caused by the terrain, thereby achieving the advantage that the stability criterion method can be applied in rugged terrain;

[0045] 2) Because the present invention adopts the capture point inference, it overcomes the problem that the stability criterion method in the prior art does not consider the moving speed factor, thereby achieving the advantage that the stability criterion method can perform comparison and judgment at any moving speed;

[0046] 3) Because the present invention adopts the method of constructing the critical stability margin, it overcomes the problem that the stability criterion method in the prior art is single when judging the state, and there are only stable and unstable states, thereby achieving the advantage of comparing and judging different stable states corresponding to different orders of stability margins;

[0047] 4) Because the present invention adopts the combination of ESM energy stability margin and capture point inference, it overcomes the difficulty in applying the stability criterion method in the prior art to the judgment index, thereby obtaining the speed and capture point index corresponding to the center of mass speed judgment and the stability margin interval judgment. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 The figure is a flow chart of a stability criterion method for a quadruped robot based on critical stability margin.

[0049] Figure 2 Schematic diagram for constructing the first-order stability margin of a quadruped robot in the stationary standing condition.

[0050] Figure 3 A simplified diagram of the virtual legs of a quadruped robot moving.

[0051] Figure 4 Schematic diagram of the graded critical stability margin of a quadruped robot.

[0052] Figure 5 Schematic diagram of the stability criterion method based on the critical stability margin during the motion process of a quadruped robot. DETAILED DESCRIPTION

[0053] The present invention is further described and illustrated below in conjunction with specific embodiments. The embodiments are merely exemplary of the present disclosure and do not define the scope of limitation. The technical features of each embodiment of the present invention may be combined accordingly without conflicting with each other.

[0054] like Figure 1 As shown, the present invention comprises the following steps:

[0055] Step 1, calibrating the quadruped robot data in a stationary standing state to obtain parameters of the quadruped robot in a stationary standing state; the parameters include a body length 2a, a body width 2b, and a height Z of the body mass center from the ground;

[0056] Step 2, constructing the first-order stability margin of the robot according to the parameters obtained in step 1;

[0057] like Figure 2 As shown in the figure, the first-order stability margin of the quadruped robot is constructed when it is standing still. When standing still, the two diagonal legs of the quadruped robot are simplified into a virtual leg, and the virtual leg support point is taken as the origin, and the polar axis is horizontally forward to establish a polar coordinate representation: Assuming that the ground friction coefficient is infinite, the ESM energy

[0058] The overturning potential energy mgΔh corresponding to the required height difference Δh in the direction of the boundary or supporting leg, and the first-order stability margin boundary expressed in polar coordinates is plotted according to the position of the ground capture point corresponding to the critical speed:

[0059] The first-order stability margin boundary equates the kinetic energy of the quadruped robot's motion state to the overturning potential energy required along the support boundary or the direction of the supporting leg, which can be obtained from the ESM energy stability margin:

[0060]

[0061]

[0062] Among them, Δh is the height difference from the center of mass to the highest point when the quadruped robot overturns along the direction of movement, which can be calculated by the geometric relationship between the legs and the body, and g is the gravitational acceleration. The first-order motion velocity corresponding to the first-order stability margin boundary can be obtained:

[0063]

[0064] Construct the vertical projection point P of the centroid z , we can get the position of the stability margin boundary:

[0065]

[0066] Among them, P margin1 is the boundary equation of the first-order stability margin at rest.

[0067] Set the origin at the virtual leg landing point P z , the polar axis is horizontally forward, expressed in polar coordinates:

[0068]

[0069]

[0070]

[0071]

[0072] Among them, ρ margin 1 is the first-order stability margin boundary equation during motion, ρ body is the geometric shape constraint of the fuselage, θ is the angle between the velocity direction of the center of mass and the polar axis, in the first quadrant of the rectangular coordinate system:

[0073] In a specific embodiment of the present invention, by introducing the ESM energy stability margin for stability judgment, this stability criterion method can be extended to any rugged terrain. It is necessary to judge the required overturning potential along the supporting leg boundary and consider the height difference caused by the landing point terrain to construct the first-order stability margin:

[0074]

[0075] Among them, ΔZ is the height difference caused by the terrain where the supporting leg lands, P Z is the height of the virtual leg from the ground.

[0076] Furthermore, the derivation of the first-order stability margin boundary is as follows: Assuming that the ground friction coefficient is infinite, the relationship between the first-order stability margin boundary and the ESM energy stability margin can be deduced, that is, the kinetic energy of the quadruped robot is equivalent to the overturning potential energy required along the support boundary or the support leg direction, and further the maximum value of this energy is equivalent to the capture point position to construct the first-order stability margin boundary. Since the geometric relationship constraint between the legs and the fuselage has the characteristics of a small vertical boundary distance and a long diagonal, the first-order stability margin boundary presents a four-sided arc feature.

[0077] Step 3, obtaining information of the quadruped robot in real time during the movement according to the sensor; the information includes the position P of the center of mass of the body, the speed of the center of mass of the body Body center of mass acceleration and leg posture; in a specific embodiment of the present invention, the information is obtained by setting a three-dimensional force sensor at the foot end of the quadruped robot, a body IMU sensor, and a leg motion joint encoder, wherein the foot end three-dimensional force sensor is used to detect the force exerted on the foot end of the robot; the body IMU sensor is used to detect the acceleration and angular velocity of the body center of mass; the leg motion joint encoder is used to detect the elongation and joint angle; Figure 3 As shown in the figure, the simplified model of the virtual leg of the quadruped robot during motion simplifies the robot legs through the concept of virtual legs, and constrains the center of mass height to remain unchanged, and then simplifies it into a linear inverted pendulum model and constructs the capture point position. The relationship between the virtual leg and the actual supporting leg is equivalent to the geometric relationship and force relationship, and then the simplified leg model and its laws can be applied. In this way, the center of mass position P of the fuselage and the speed of the center of mass of the fuselage can be obtained. Body center of mass acceleration And leg posture.

[0078] Furthermore, the supporting legs of the quadruped robot are simplified by virtual legs, and the height of the center of mass is kept constant, and then simplified to a linear inverted pendulum model, and the height of the center of mass is constrained to be constant, and then simplified to a linear inverted pendulum model, so that the capture area theory can be applied. Virtual leg simplification:

[0079] r1cosα1+r2cosα2=2rcosα

[0080] r1cosα1-r2cosα2=2rcosγ

[0081]

[0082]

[0083]

[0084] Where d is the distance from the center of mass to the supporting leg, r1 and r2 are the lengths of supporting leg 1 and supporting leg 2, α1 and α2 are the angles between supporting leg 1 and supporting leg 2 and the vertical direction, F1 and F2 are the forces on the foot ends of supporting leg 1 and supporting leg 2, M1 and M2 are the moments on supporting leg 1 and supporting leg 2; r is the length of the virtual leg, α is the angle between the virtual leg and the vertical direction, F xy 、F z is the equivalent force in the horizontal and vertical directions at the foot end of the virtual leg, M is the equivalent moment of the virtual leg, and γ is the angle between the virtual leg and the horizontal direction.

[0085] Step 4: construct the first-order stability margin constructed in step 2 and the information obtained in step 3 to construct and judge the hierarchical stability margin, obtain the stability state of the current quadruped robot, repeat steps 3 and 4, and continuously judge the stability state.

[0086] like Figure 4 As shown in the figure, the hierarchical critical stability margin of the quadruped robot is calculated according to the virtual leg landing point P z and critical stability margin ρ margin :

[0087]

[0088]

[0089]

[0090] Establish polar coordinates and place the origin at the virtual leg landing point P z , the polar axis is horizontally forward, and the polar coordinates are established and drawn. Since the distance difference between the second-order and third-order stability margins and the first-order stability margins is equal, the boundaries of the second-order and third-order stability margins also present a four-sided arc feature, and the critical stability margin presents a contour feature as a whole.

[0091] like Figure 5 As shown in Figure 1, the stability criterion method based on the critical stability margin is used during the motion process of the quadruped robot. The critical stability margin boundary constructed above is used to calculate the current speed of the quadruped robot. The captured point position ρ in the transformed polar coordinates cp Make a comparison.

[0092] If the capture point position corresponding to the current center of mass velocity is within the first-order stability margin, the quadruped robot does not need to make corresponding adjustments even if it is in a stable state;

[0093] If it is within the first-order and second-order stability margins, the quadruped robot only needs to take one step immediately in the direction of the center of mass velocity to be stable;

[0094] If it is within the second-order and third-order stability margins, the quadruped robot only needs to keep moving in the direction of the center of mass velocity to be stable.

[0095] The robot legs are simplified through the concept of virtual legs and the center of mass height is constrained to remain unchanged, and then simplified to a linear inverted pendulum model by applying the capture region theory.

[0096] Among them, the center of mass is highly constrained to be a constant value, and the linear inverted pendulum dynamics equation and Hamiltonian energy integral can be obtained:

[0097]

[0098]

[0099]

[0100] Where H is the Hamiltonian energy integral, which means the conserved energy when the simplified model of the leg moves.

[0101] The capture region theory assumes that the Hamiltonian energy integral is zero, and the capture point position can be obtained:

[0102]

[0103] Where P cp To capture the point location, its size is only affected by the center of mass velocity.

[0104] Assume the velocity of the center of mass Parameters, speed With the velocity direction θ, convert it to polar coordinates:

[0105]

[0106] Then the hierarchical critical stability margin expressed in polar coordinates is constructed.

[0107] Furthermore, the critical stability margin is constructed by converting the corresponding energy into the capture point position.

[0108] Among them, the first-order critical stability margin is constructed by converting the ESM energy stability margin into the capture point position, and the corresponding critical stability margin reference diagram is drawn by polar coordinates;

[0109] The second-order critical stability margin is constructed by adding a step to capture the position l based on the first-order critical stability margin; where l is the swing step length of the swing leg or the equivalent step length of the virtual leg.

[0110] The third-order critical stability margin is also called the limit stability margin, which is composed of the first-order critical stability margin of the quadruped robot plus the maximum capture area. Assuming that there is a maximum area boundary d max , then after walking one step to d max-1 According to the linear inverted pendulum dynamics equation, the process can be obtained:

[0111]

[0112]

[0113] Among them, t0 is the current time, Δt is the time corresponding to one step;

[0114] According to the recursive relationship, the maximum capture area boundary value can be obtained:

[0115]

[0116] The critical stability margin of each order is expressed by polar coordinates and projected onto the ground:

[0117] First-order critical stability margin:

[0118]

[0119] Second-order critical stability margin:

[0120]

[0121] Third-order critical stability margin:

[0122]

[0123] Furthermore, the critical speed is calculated from the corresponding critical stability margin.

[0124] Among them, the first-order critical speed is the equivalent kinetic energy corresponding to the ESM energy stability margin.

[0125] The second-order critical velocity is the first-order critical velocity plus an additional center-of-mass velocity that captures position transformation.

[0126] The third-order critical speed is also called the limiting speed, which is the center-of-mass speed converted from the maximum capture area.

[0127] The relationship is inferred from the relationship between the capture point and the center of mass velocity:

[0128]

[0129] First-order critical speed:

[0130]

[0131] When the current center-of-mass velocity of the quadruped robot is less than the first-order critical velocity, the quadruped robot does not need to make corresponding adjustments to reach a stable state;

[0132] Second order critical speed:

[0133]

[0134] When the current center-of-mass velocity of the quadruped robot is between the first-order critical velocity and the second-order critical velocity, the quadruped robot needs to take a step immediately in the direction of the center-of-mass velocity to stabilize;

[0135] The third-order critical speed is:

[0136]

[0137] When the center-of-mass velocity of the current quadruped robot is between the second-order critical velocity and the third-order critical velocity, the quadruped robot needs to continue moving in the direction of the center-of-mass velocity to stabilize.

[0138] The purpose is to determine the stability state by constructing a critical stability margin and judging the position of the capture point corresponding to the current velocity of the center of mass of the quadruped robot.

[0139] If the capture point position corresponding to the current center of mass velocity is within the first-order stability margin, the quadruped robot does not need to make corresponding adjustments even if it is in a stable state;

[0140] If it is within the first-order and second-order stability margins, the quadruped robot only needs to take one step immediately in the direction of the center of mass velocity to be stable;

[0141] If it is within the second-order and third-order stability margins, the quadruped robot only needs to keep moving in the direction of the center of mass velocity to be stable.

[0142] The existing stability margin adjusts the stability criterion method as follows: construct a ground reference point with physical meaning according to the force condition or center of mass position of the quadruped robot, representative examples include ZMP zero moment point, COP pressure center point, SSM static stability margin, FASM force angle method, and then make a judgment with the support margin. If the support margin is within the support margin, it is stable, otherwise it is unstable. The solution of the present invention adjusts the stability margin as follows: define the critical stability margins of the first order, second order, and third order, and compared with the existing solution, the corresponding different stable states are added to the stability margin, so that the stability has a broader judgment standard.

[0143] The adjustment of the hypothetical model in the existing capture point method is: applied at the level of a single-leg simplified model without considering the impact of the actual model. The solution of the present invention adjusts the capture point method by simplifying the model through virtual legs and applying the ESM energy stability margin to retain the impact of the actual model. Compared with the existing solution, the solution of the present invention improves the consideration of the impact of the quadruped robot model on the capture point in model application, making the capture point more applicable to the actual model.

[0144] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. For ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A stability criterion method for a quadruped robot based on critical stability margin, characterized in that: The following steps are involved: Step 1: calibrate the quadruped robot data in a stationary standing state to obtain the parameters of the quadruped robot in a stationary standing state; the parameters include the fuselage length 2a, the fuselage width 2b, and the height Z of the fuselage center of mass from the ground; Step 2: construct the first-order critical stability margin of the robot according to the parameters obtained in step 1; Step 3: Obtain information about the quadruped robot in real time during movement using sensors; the information includes the center of mass position P of the body, the center of mass velocity of the body Body center of mass acceleration and leg posture; Step 4: Construct the hierarchical stability margin through the first-order critical stability margin constructed in step 2 and the information obtained in step 3, and judge the current stability of the quadruped robot to obtain the current stability state of the quadruped robot. Repeat the operations of steps 3 and 4 to continuously judge the stability state. The first-order stability margin of the robot constructed in step 2 is specifically: Assuming that the friction coefficient of the ground is infinite, the kinetic energy of the motion state of the quadruped robot is equivalent to the overturning potential energy required along the support boundary or the direction of the supporting leg. The relationship between the first-order stability margin boundary and the ESM energy stability margin is derived. The two diagonal legs of the quadruped robot are simplified into a virtual leg, and the virtual leg support point is taken as the origin, and the polar axis direction is horizontally forward to establish a polar coordinate representation: Among them, θ is the angle between the velocity direction of the center of mass and the polar axis, in the first quadrant of the rectangular coordinate system: ρ margin1 is the first-order critical stability margin; x is the coordinate in the polar axis direction, y is the coordinate in the horizontal plane perpendicular to the polar axis direction, ρ body is the fuselage geometry constraint, is the first-order critical velocity, g is the gravitational acceleration, and Δh is the height difference from the center of mass to the highest point when the quadruped robot overturns along the direction of motion; The step 4 of constructing the hierarchical stability margin is specifically as follows: The critical stability margin is constructed by converting the corresponding energy into the capture point position, and the corresponding step-by-step stability margin reference diagram is plotted by polar coordinates; Among them, the first-order critical stability margin is: The second-order critical stability margin is constructed based on the first-order critical stability margin with one more step to capture the position l: The third-order critical stability margin is constructed based on the first-order critical stability margin plus the maximum capture area: Among them, ρ body is the body geometry constraint, the capture position l is determined by the step length of the quadruped robot, and Δt is the time required for the quadruped robot to take a step.

2. The quadruped robot stability criterion method according to claim 1, characterized in that: When constructing the first-order stability margin of the robot, after considering the height difference caused by the terrain of the foothold, the first-order stability margin is: Among them, ΔZ is the height difference caused by the terrain where the actual support leg lands, P Z is the height of the virtual leg from the ground.

3. The quadruped robot stability criterion method according to claim 1, characterized in that: The boundary of the first-order critical stability margin presents a quadrilateral arc in polar coordinates.

4. The quadruped robot stability criterion method according to claim 1, characterized in that: In the step 4, judging the stability state of the current quadruped robot includes judging the velocity of the center of mass of the quadruped robot and judging the stability margin interval.

5. The quadruped robot stability criterion method according to claim 4, characterized in that: The quadruped robot mass center velocity determination is specifically as follows: based on constructing a hierarchical stability margin, a corresponding critical velocity is calculated, and the current quadruped robot mass center velocity is determined to obtain the current stability state of the quadruped robot; Among them, the first-order critical speed is: When the current velocity of the center of mass of the quadruped robot is less than the first-order critical velocity, the quadruped robot is in a stable state without making corresponding adjustments; The second-order critical speed is: When the current center-of-mass velocity of the quadruped robot is between the first-order critical velocity and the second-order critical velocity, the quadruped robot needs to take a step immediately in the direction of the center-of-mass velocity to stabilize; The third-order critical speed is: When the center-of-mass velocity of the current quadruped robot is between the second-order critical velocity and the third-order critical velocity, the quadruped robot needs to continue moving in the direction of the center-of-mass velocity to stabilize.

6. The quadruped robot stability criterion method according to claim 4, characterized in that: The determination of the stability margin interval of the quadruped robot is specifically as follows: the stability margin interval where the current state of the quadruped robot is located is determined by drawing a corresponding step-by-step stability margin reference diagram using polar coordinates: If the capture point position corresponding to the current center of mass velocity is within the first-order stability margin, the quadruped robot does not need to make corresponding adjustments even if it is in a stable state; If the capture point position corresponding to the current center of mass velocity is between the first-order stability margin and the second-order stability margin, the quadruped robot only needs to take a step in the direction of the center of mass velocity immediately to stabilize; If the capture point position corresponding to the current center of mass velocity is between the second-order stability margin and the third-order stability margin, the quadruped robot needs to continue moving in the direction of the center of mass velocity to achieve stability.

7. The quadruped robot stability criterion method according to claim 6, characterized in that: Determine the capture point position corresponding to the current center of mass velocity as follows: After simplification, the virtual leg restricts its motion to a linear inverted pendulum, where the center of mass is highly constrained to be a constant value, and the capture point equation is derived from the linear inverted pendulum dynamics equation and Hamiltonian energy integral: Inverted pendulum dynamics equation: Hamiltonian energy integral: The capture region theory assumes that the Hamiltonian energy integral is zero, and the capture point position can be obtained: Among them, P cp The capture point location.

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