Motion modeling method of four-wheel drive climbing robot

Abstract

The invention discloses a motion modeling method for a four-wheel drive climbing robot. The motion modeling method comprises the steps that motion parameters of the climbing robot are acquired; according to the motion parameters, the motion acceleration of the robot is obtained; torque analysis is conducted on the axis where the wheels of the climbing robot make contact with the wall face, and a torque equation in the axis direction is established; performing positive pressure analysis on the climbing robot, and obtaining the positive pressure of the climbing robot in combination with the moment equation; analyzing the friction force of the climbing robot, and establishing an overall friction motion equation in combination with the motion acceleration and the positive pressure of the climbing robot; and on the basis of the overall friction motion equation, positive pressure of a negative pressure cavity is obtained in combination with constraint conditions meeting walking. The method has high application value in the aspect of motion planning of the wheel-driven climbing robot.

Description

Technical Field

[0001] The invention belongs to the field of robot modeling, and in particular relates to a motion modeling method of a four-wheel drive climbing robot. Background Art

[0002] With the continuous development of robotics technology and the expansion of its application fields, wheel-driven climbing robots have shown unique advantages in working in complex environments. This type of robot can not only move flexibly on flat ground, but also work on vertical or inclined surfaces through a specific climbing mechanism, which greatly expands its working range and adaptability. However, in order to achieve stable and efficient operation of wheel-driven climbing robots in various environments, in-depth research on their motion modeling is particularly important.

[0003] At present, most of the research on wheel-driven climbing is concentrated on structural design and control systems. There are still some deficiencies in motion modeling, which cannot well reflect the relationship between motion and negative pressure in the negative pressure chamber. Therefore, a motion modeling method for a four-wheel-drive climbing robot is urgently needed to solve the above problems. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a motion modeling method for a four-wheel drive climbing robot, which can well reflect the relationship between the motion and the negative pressure of the negative pressure chamber.

[0005] To achieve the above object, the present invention provides a motion modeling method for a four-wheel drive climbing robot, comprising:

[0006] Get the motion parameters of the climbing robot;

[0007] According to the motion parameters, obtaining the motion acceleration of the robot;

[0008] Conduct torque analysis on the axis where the climbing robot's wheels contact the wall, and establish the torque equation in the axis direction;

[0009] Performing a positive pressure analysis on the climbing robot, and obtaining the positive pressure of the climbing robot in combination with the torque equation;

[0010] Analyze the friction force of the climbing robot, and establish the overall friction motion equation by combining the motion acceleration and the positive pressure of the climbing robot;

[0011] Based on the overall friction motion equation and in combination with satisfying walking constraints, the positive pressure of the negative pressure chamber is obtained.

[0012] Optionally, the motion parameters of the climbing robot include: the lateral distance and longitudinal distance of the wheels, the distance from the center of gravity of the robot to the wall, the weight of the robot, the inclination angle of the robot with respect to the vertical direction, the area of ​​the negative pressure chamber, the pressure difference of the negative pressure chamber, the static friction coefficient between the wheels and the wall, and the static friction coefficient between the negative pressure chamber and the wall.

[0013] Optionally, according to the motion parameter, obtaining the motion acceleration of the robot includes:

[0014] According to the motion parameters, obtaining the overall angular velocity of the robot;

[0015] According to the overall angular velocity, obtaining the movement speed of the wheel;

[0016] Perform geometric analysis on the distance from the wheel to the center of rotation to obtain the first distance;

[0017] According to the movement speed, obtaining the linear speed of the robot;

[0018] Establishing a forward kinematics model of the robot according to the first distance and linear velocity;

[0019] The motion acceleration of the robot is obtained according to the forward kinematics model of the robot.

[0020] Optionally, the forward kinematic model of the robot is:

[0021]

[0022] Among them, v cx is the component of the robot's velocity in the x direction, ω c is the angular velocity of the robot as a whole, V L 、V R are the linear velocities of the left and right sides of the climbing robot respectively, and D is the lateral distance between the driving wheel 1 and the driving wheel 2.

[0023] Optionally, according to the forward kinematics model of the robot, obtaining the motion acceleration of the robot includes:

[0024] According to the forward kinematics model of the robot, obtaining the component of the robot velocity in the x direction;

[0025] The velocity component is derived to obtain the motion acceleration of the robot.

[0026] Optionally, the moment equation in the axis direction includes:

[0027]

[0028] Among them, F Pis the suction force generated by the negative pressure chamber, D is the lateral distance between wheel 1 and wheel 2, L is the longitudinal distance between wheel 1 and wheel 4, N1 is the positive pressure of wheel 1, N2 is the positive pressure of wheel 2, N4 is the positive pressure of wheel 4, H is the distance from the center of gravity of the robot to the wall, G is the gravity of the robot, and θ is the inclination angle of the robot with the vertical direction.

[0029] Optionally, obtaining the positive pressure of the climbing robot includes:

[0030] Analyze the positive pressure of the wheels of the climbing robot, and obtain the positive pressure of the wheels in combination with the torque equation;

[0031] The direction of the climbing robot perpendicular to the wall is analyzed, and the positive pressure perpendicular to the entire wall is obtained in combination with the positive pressure of the wheels.

[0032] Optionally, the overall friction motion equation is:

[0033] μ1(N1+N2+N3+N4)-2μ2N5-G cosθ=a cx M

[0034] Among them, μ1 is the friction coefficient between the driving wheel and the wall, μ2 is the friction coefficient between the negative pressure chamber and the wall, N1 is the positive pressure of wheel 1, N2 is the positive pressure of wheel 2, N3 is the positive pressure of wheel 3, N4 is the positive pressure of wheel 4, H is the distance from the center of gravity of the robot to the wall, G is the gravity of the robot, N5 is the reverse positive pressure of the wall on the negative pressure chamber, θ is the inclination angle of the robot with the vertical direction, a cx is the robot's acceleration, and M is the robot's mass.

[0035] Compared with the prior art, the present invention has the following advantages and technical effects:

[0036] The present invention is aimed at a four-wheeled climbing robot with two negative pressure chambers, fully considers the interaction between various parts of the robot and the wall (including the interaction between the negative pressure chamber and the wall), and establishes a motion model of the climbing robot. The negative pressure value required for its movement is obtained through the movement of the climbing robot. It has strong application value in the motion planning of wheel-driven climbing robots. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0038] Figure 1 is a flow chart of a motion modeling method for a four-wheel drive climbing robot according to an embodiment of the present invention;

[0039] Figure 2Schematic diagram of mechanical analysis of an embodiment of the present invention, (a) is a top view, (b) is a side view;

[0040] Figure 3 FIG. 4 is a schematic diagram of motion analysis according to an embodiment of the present invention. DETAILED DESCRIPTION

[0041] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0042] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0043] The present invention provides a motion modeling method for a four-wheel drive climbing robot. Figure 1 As shown, specifically including:

[0044] Get the motion parameters of the climbing robot;

[0045] According to the motion parameters, obtaining the motion acceleration of the robot;

[0046] Conduct torque analysis on the axis where the climbing robot's wheels contact the wall, and establish the torque equation in the axis direction;

[0047] Performing a positive pressure analysis on the climbing robot, and obtaining the positive pressure of the climbing robot in combination with the torque equation;

[0048] Analyze the friction force of the climbing robot, and establish the overall friction motion equation by combining the motion acceleration and the positive pressure of the climbing robot;

[0049] Based on the overall friction motion equation and in combination with satisfying walking constraints, the positive pressure of the negative pressure chamber is obtained.

[0050] Furthermore, the motion parameters of the climbing robot are obtained, including: the lateral distance and longitudinal distance of the wheels, the distance from the center of gravity of the robot to the wall, the weight of the robot, the inclination angle of the robot with respect to the vertical direction, the area of ​​the negative pressure chamber, the pressure difference of the negative pressure chamber, the static friction coefficient between the wheels and the wall, and the static friction coefficient between the negative pressure chamber and the wall.

[0051] Specifically, Figure 2As shown, the wheel-driven climbing robot includes four driving wheels and two negative pressure chambers, which are all installed on the robot body. It is characterized in that the rotating axes of the two driving wheels at the front end are collinear, and the rotating axes of the two driving wheels at the rear end are collinear. When looking down at the robot, the left driving wheel at the front end and the left driving wheel at the rear end are coplanar; the right driving wheel at the front end and the right driving wheel at the rear end are coplanar. When looking down at the robot, the wheels are numbered from top to bottom in clockwise order as driving wheel No. 1, driving wheel No. 2, driving wheel No. 3, and driving wheel No. 4, and the axes of the four driving wheels are in the same plane. The two negative pressure chambers are numbered as negative pressure chamber No. 1 and negative pressure chamber No. 2, respectively, and are located on both sides of the vertical axis of the robot and are symmetrical about the vertical axis and the horizontal axis.

[0052] like Figure 2 As shown, the lateral distance D between the driving wheel 1 and the driving wheel 2 is measured, the longitudinal distance L between the driving wheel 1 and the driving wheel 4 is measured, the distance H from the center of gravity of the robot to the wall is measured by software, the weight of the robot G is measured, the inclination angle θ of the robot with respect to the vertical direction at this moment is measured, the friction coefficient μ1 between the driving wheel and the wall and the friction coefficient μ2 between the negative pressure chamber and the wall (μ1>μ2) are obtained by searching the data, the area of ​​the negative pressure chamber is measured to be S, and the negative pressure difference of the unknown negative pressure chamber is defined as ΔP.

[0053] Further, according to the motion parameters, obtaining the motion acceleration of the robot includes:

[0054] According to the motion parameters, the overall angular velocity of the robot is obtained;

[0055] According to the overall angular velocity, obtaining the movement speed of the wheel;

[0056] Perform geometric analysis on the distance from the wheel to the center of rotation to obtain the first distance;

[0057] According to the movement speed, obtaining the linear speed of the robot;

[0058] Establishing a forward kinematics model of the robot according to the first distance and linear velocity;

[0059] The motion acceleration of the robot is obtained according to the forward kinematics model of the robot.

[0060] Specifically, S001: Figure 3 As shown, point A1 is defined as being located at the center of mass of driving wheel 1. A1xy To define the coordinate system of the driving wheel 1 of the climbing robot, the origin of the coordinate system is located at point A1. Similarly, using O A2xy , O A3xy , O A4xy To define the coordinate system of driving wheels 2, 3, and 4, the origin of the coordinate system is located at A2, A3, and A4 respectively. OPoint is the center of the circle where the climbing robot makes a turning motion, i.e., the center of rotation, ω c is the angular velocity of the robot as a whole; define point C as the center of motion of the robot, assuming it is located on the vertical axis of the robot, and define v c is the robot's moving speed, d c From point C to C O The distance between the points.

[0061] S002: Define the distance from each wheel to the rotation center as d i (i is 1, 2, 3, 4), then the movement speed v of each wheel i =d i ω c .Right now

[0062] S003: Define the angle between the line connecting the center of mass and the rotation center of each driving wheel and the line connecting the robot's geometric center and the rotation center as α i (i is 1, 2, 3, 4), for the sports center,

[0063] Among them, α c For CC O The angle between the robot's geometric center and rotation center, v cx is the component of the robot's velocity in the x direction, d cy From point C to C O The distance of the point in the y direction.

[0064] Similarly, for wheel 1 and wheel 2, we can get

[0065] Among them, v 1x is the component of wheel 1 velocity in the x direction, d 1y For rounds 1 to C O The distance of the point in the y direction, v 2x is the component of wheel 2 velocity in the x direction, d 2y For round 2 to C O The distance of the point in the y direction.

[0066] S004: Yes Figure 3 By geometric analysis in the y-axis direction, we can get d i The geometric relationship in the y-axis direction is

[0067] S005: Define V L 、V Ris the linear velocity of the left and right sides of the climbing robot. Since the linear velocity on the same side is the same, the linear velocity of wheel 1 and wheel 4 is equal, and the linear velocity of wheel 2 and wheel 3 is equal, that is,

[0068] S006: According to the above steps S003 to S005, it can be known that:

[0069] By solving and transforming it, we can get the forward kinematic model of the four-wheel drive robot.

[0070] By taking the derivative of the robot's velocity in the x direction, we can get the robot's acceleration in the x direction.

[0071] Specifically, assuming that the robots are all rigid structures, a mechanical analysis is performed on their overall structures to complete the mechanical modeling of the robots and solve them:

[0072] S007: Perform torque analysis on the axis of contact between the wheel of the wheel-driven climbing robot and the wall, such as Figure 2 and Figure 3 As shown, the axis of contact between wheels 3 and 4 and the wall is analyzed. From the direction of wheel 3 pointing to wheel 4, it is subjected to the counterclockwise moment generated by the positive pressure N1 and N2 of wheels 1 and 2 and the gravity G of the robot, and is subjected to the adsorption force F P Similarly, the axis of contact between wheels 2 and 3 and the wall is analyzed. From the direction of wheel 2 pointing to wheel 3, it is subjected to the counterclockwise torque generated by the positive pressure N1 and N4 of wheels 1 and 4 and the gravity G of the robot, and is subjected to the adsorption force F P For the clockwise torque generated by it, according to the geometric relationship of the robot, the torque equations in the two axis directions are established, namely:

[0073] Among them, F P is the suction force generated by the negative pressure chamber, D is the lateral distance between wheel 1 and wheel 2, L is the longitudinal distance between wheel 1 and wheel 4, N1 is the positive pressure of wheel 1, N2 is the positive pressure of wheel 2, N4 is the positive pressure of wheel 4, H is the distance from the center of gravity of the robot to the wall, G is the gravity of the robot, and θ is the inclination angle of the robot with the vertical direction.

[0074] Therefore, we can get the expression of N2 with respect to N1, namely: And the expression of N4 with respect to N1, that is:

[0075] S008: By analyzing the positive pressure of the wheels of the wheel-driven climbing robot, a relational expression of the positive pressure between the wheels can be obtained, namely: N1+N3=N2+N4.

[0076] Substituting the two expressions obtained in step S001 into it, we can get the expression of N3 with respect to N1, namely:

[0077] S009: Analyze the direction of the wheel-driven climbing robot perpendicular to the wall, such as Figure 2 As shown in (b), it is subjected to an adsorption force 2F directed toward the wall. P , the wall faces the four driving wheels' reverse positive pressure N i (i is 1, 2, 3, 4). Since the negative pressure cavity is in contact with the wall, a positive pressure N5 will be generated from the wall to the negative pressure cavity. The positive pressure equation perpendicular to the entire wall is established, namely: N1+N2+N3+N4+2N5=2F P .

[0078] Then, the expressions of N2, N3, N4 and N1 obtained in step S007 and step S008 are substituted into the above equation to obtain the relationship expression between N1 and N5, namely: or

[0079] S010: Analyze the friction of a wheel-driven climbing robot, such as Figure 2 As shown in (a), in the x-axis direction, the driving wheel is subjected to an upward friction driving force F. fi (i is 1, 2, 3, 4), the downward friction resistance F of the negative pressure chamber f5 , and the gravity in the x-axis direction, their combined force makes the robot have tangential acceleration in the x-axis direction, and the overall friction motion equation is established, that is: μ1(N1+N2+N3+N4)-2μ2N5-G cos θ=a cx M.

[0080] Where M is the mass of the climbing robot, F fi =μ1N i (i is 1, 2, 3, 4), F f5 =μ2N5, μ1 is the friction coefficient between the driving wheel and the wall, and μ2 is the friction coefficient between the negative pressure chamber and the wall.

[0081] Substitute the expressions obtained from steps S007 to S009 into the above equation to obtain N1 and F P and N5 and F P The relational expression of

[0082] S011: Analyze the adsorption force of the wheel-driven climbing robot. Its negative pressure chamber generates negative pressure, which makes the robot generate an adsorption force perpendicular to the wall, that is: F P =ΔP×S,

[0083] Among them, F P is the adsorption force generated by the negative pressure chamber, ΔP is the negative pressure generated by the negative pressure chamber, and S is the area of ​​the negative pressure chamber.

[0084] Substituting the above equation into the expression obtained in S0010, we can get the relationship expression between the positive pressure N1 of wheel 1, the positive pressure N5 of the negative pressure chamber and the negative pressure ΔP, that is:

[0085]

[0086] Since the robot cannot overturn or fall off when moving on the wall, its driving wheels and negative pressure chamber must always keep in contact with the wall. Therefore, the positive pressure between the top driving wheel 1 and the negative pressure chamber and the wall must always be greater than zero, that is, Therefore, the relationship between the minimum negative pressure difference ΔP and the robot motion can be obtained, that is,

[0087]

[0088] Where D is the lateral distance between wheel 1 and wheel 2, L is the longitudinal distance between wheel 1 and wheel 4, H is the distance from the center of gravity of the robot to the wall, G is the gravity of the robot, θ is the inclination angle of the robot with respect to the vertical direction, μ1 is the friction coefficient between the driving wheel and the wall, μ2 is the friction coefficient between the negative pressure chamber and the wall, M is the mass of the robot, and V L 、V R is the linear velocity of the left and right sides of the climbing robot, and S is the area of ​​the negative pressure chamber.

[0089] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A motion modeling method for a four-wheel drive climbing robot, characterized in that: include: Get the motion parameters of the climbing robot; According to the motion parameters, obtaining the motion acceleration of the robot; Conduct torque analysis on the axis where the climbing robot's wheels contact the wall, and establish the torque equation in the axis direction; Performing a positive pressure analysis on the climbing robot, and obtaining the positive pressure of the climbing robot in combination with the torque equation; Analyze the friction force of the climbing robot, and establish the overall friction motion equation by combining the motion acceleration and the positive pressure of the climbing robot; Based on the overall friction motion equation and in combination with satisfying walking constraints, the positive pressure of the negative pressure chamber is obtained.

2. The motion modeling method of a four-wheel drive climbing robot according to claim 1, characterized in that: The motion parameters of the climbing robot include: the lateral distance and longitudinal distance of the wheels, the distance from the center of gravity of the robot to the wall, the weight of the robot, the inclination angle of the robot with respect to the vertical direction, the area of ​​the negative pressure chamber, the pressure difference of the negative pressure chamber, the static friction coefficient between the wheels and the wall, and the static friction coefficient between the negative pressure chamber and the wall.

3. The motion modeling method of a four-wheel drive climbing robot according to claim 2, characterized in that: According to the motion parameters, obtaining the motion acceleration of the robot includes: According to the motion parameters, obtaining the overall angular velocity of the robot; According to the overall angular velocity, obtaining the movement speed of the wheel; Perform geometric analysis on the distance from the wheel to the center of rotation to obtain the first distance; According to the movement speed, obtaining the linear speed of the robot; Establishing a forward kinematics model of the robot according to the first distance and linear velocity; The motion acceleration of the robot is obtained according to the forward kinematics model of the robot.

4. The motion modeling method of a four-wheel drive climbing robot according to claim 3, characterized in that: The forward kinematic model of the robot is: Among them, v cx is the component of the robot's velocity in the x direction, ω c is the angular velocity of the robot as a whole, V L 、V R are the linear velocities of the left and right sides of the climbing robot respectively, and D is the lateral distance between the driving wheel 1 and the driving wheel 2.

5. The motion modeling method of a four-wheel drive climbing robot according to claim 3, characterized in that: According to the forward kinematics model of the robot, obtaining the motion acceleration of the robot includes: According to the forward kinematics model of the robot, obtaining the component of the robot velocity in the x direction; The velocity component is derived to obtain the motion acceleration of the robot.

6. The motion modeling method of a four-wheel drive climbing robot according to claim 1, characterized in that: The moment equation in the axis direction includes: Among them, F P is the suction force generated by the negative pressure chamber, D is the lateral distance between wheel 1 and wheel 2, L is the longitudinal distance between wheel 1 and wheel 4, N1 is the positive pressure of wheel 1, N2 is the positive pressure of wheel 2, N4 is the positive pressure of wheel 4, H is the distance from the center of gravity of the robot to the wall, G is the gravity of the robot, and θ is the inclination angle of the robot with the vertical direction.

7. The motion modeling method of a four-wheel drive climbing robot according to claim 1, characterized in that: Obtaining the positive pressure of the climbing robot includes: Analyze the positive pressure of the wheels of the climbing robot, and obtain the positive pressure of the wheels in combination with the torque equation; The direction of the climbing robot perpendicular to the wall is analyzed, and the positive pressure perpendicular to the entire wall is obtained in combination with the positive pressure of the wheels.

8. The motion modeling method of a four-wheel drive climbing robot according to claim 1, characterized in that: The overall friction equation of motion is: μ1(N1+N2+N3+N4)-2μ2N5-G cos θ=a cx M Among them, μ1 is the friction coefficient between the driving wheel and the wall, μ2 is the friction coefficient between the negative pressure chamber and the wall, N1 is the positive pressure of wheel 1, N2 is the positive pressure of wheel 2, N3 is the positive pressure of wheel 3, N4 is the positive pressure of wheel 4, H is the distance from the center of gravity of the robot to the wall, G is the gravity of the robot, N5 is the reverse positive pressure of the wall on the negative pressure chamber, θ is the inclination angle of the robot with the vertical direction, a cx is the robot's acceleration, and M is the robot's mass.

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