A method, device, equipment and medium for calculating negative pressure adsorption force of a wall-climbing robot

Abstract

The present invention discloses a method, device, equipment and medium for calculating the negative pressure adsorption force of a wall-climbing robot, which relates to the technical field of wall-climbing robots and includes the following steps: analyzing the overall flow process of air fluid in the negative pressure adsorption device to obtain a first expression for characterizing the motion state of the air fluid; introducing the fluid momentum equation to obtain a second expression for characterizing the negative pressure adsorption force and the air fluid velocity; establishing a differential equation group to obtain a fluid channel pressure difference formula; combining the second expression and the fluid channel pressure difference formula to obtain the negative pressure adsorption force during the motion of the wall-climbing robot. Based on the basic theoretical foundations of fluid mechanics and aerodynamics, the present invention analyzes the motion state of the air fluid during the motion of the wall-climbing robot, and at the same time introduces the fluid momentum equation to obtain the relationship between the negative pressure adsorption force and the air fluid velocity, and finally obtains a calculation formula for the negative pressure adsorption force of the wall-climbing robot applied to the composite wellbore structure.

Description

Technical Field

[0001] The present invention relates to the technical field of wall-climbing robots, and in particular to a method, device, equipment and medium for calculating the negative pressure adsorption force of a wall-climbing robot. Background Art

[0002] In recent years, intelligent inspection robots for mines, which are a combination of coal mine safety monitoring and robot technology, have been widely used in the field of underground safety detection. As an important branch of mobile robots, wall-climbing robots expand the robot's movable space to vertical or inclined walls, extending the robot's application range and practical capabilities. Unlike robots walking on the ground, the first problem that wall-climbing robots need to solve is to obtain stable wall adhesion. While ensuring the stable adsorption of the main body, it does not affect the normal walking of the robot on the wall. How to solve the contradictory relationship between wall adsorption capacity and plane motion capacity, so that the wall-climbing robot can achieve effective adsorption, is the difficulty and focus of wall-climbing robot research. The concept and prototype of wall-climbing robots can be traced back to the 1960s. Since then, with the continuous development of science and technology and the unremitting efforts of scientific researchers, the adsorption technology of wall-climbing robots has gradually matured and developed in the direction of standardization, precision, coupling and large-scale. The adsorption technologies used by comprehensive wall-climbing robots mainly include negative pressure adsorption, bionic adsorption, climbing adsorption and electromagnetic adsorption.

[0003] The negative pressure adsorption method applies the principles of aerodynamics and creates negative pressure in a specific space through various devices and methods, so that the air pressure in the negative pressure chamber is lower than the external atmospheric pressure. The pressure difference between the inside and the outside is used to obtain the normal thrust of the outside toward the wall, thereby forming an adsorption force. In actual applications, different negative pressure generating devices can be used according to specific functions and environmental requirements, but the basic principles are the same.

[0004] At present, wall-climbing robots using negative pressure adsorption are generally used in scenarios with good wall conditions. The analysis of the movement state of air fluid during the movement of the wall-climbing robot is not in-depth enough, and the research on the factors affecting the negative pressure adsorption force is not comprehensive enough, resulting in large errors in the calculation results of the negative pressure adsorption force. Summary of the invention

[0005] The present invention provides a method, device, equipment and medium for calculating the negative pressure adsorption force of a wall-climbing robot, which solves the problem that the existing wall-climbing robots using negative pressure adsorption are generally used in scenarios with good wall conditions, but the research on the sub-item velocity of air fluid is not in-depth enough, resulting in large errors in the calculation results of the negative pressure adsorption force.

[0006] The present invention provides a method for calculating the negative pressure adsorption force of a wall-climbing robot, wherein the negative pressure adsorption force is generated by a negative pressure adsorption device, and the method comprises the following steps:

[0007] The overall flow process of air fluid in a negative pressure adsorption device of a wall-climbing robot is analyzed to obtain a first expression for characterizing the motion state of the air fluid; the negative pressure adsorption device includes a negative pressure chamber, a centrifugal fan and a sealing device;

[0008] In the process of analyzing the flow of air fluid in the negative pressure chamber, a fluid momentum equation is introduced to obtain the momentum change rate of the air fluid; the momentum change rate of the air fluid is transformed and combined with the first expression to obtain a second expression for characterizing the negative pressure adsorption force and the air fluid velocity;

[0009] In the process of analyzing the flow of air fluid in the fluid channel of the sealing device, a differential equation group is established, and the differential equation group is derived and replaced in magnitude to obtain a pressure difference formula of the fluid channel;

[0010] The second expression is transformed and substituted into the fluid channel pressure difference formula to obtain the negative pressure adsorption force during the movement of the wall-climbing robot.

[0011] Preferably, the overall flow process of the air fluid includes a first stage and a second stage, wherein the first stage is that the static air fluid in the negative pressure chamber generates lateral flow due to the suction force of the centrifugal fan, and then the gas leaked from the sealing device is supplemented into the negative pressure chamber to finally achieve flow balance, and the second stage is that the centrifugal fan drives the air fluid to rotate at a high speed, and then the centrifugal force throws the air out of the impeller and discharges it from the outlet.

[0012] Preferably, the first expression is as follows:

[0013]

[0014] Where N(t) is the extensive function of the fluid system, KM1 is the control surface on the left side of the control body, and KM2 is the control surface on the right side of the control body. is the rate of change of the total physical quantity with time t, v1 is the air fluid inflow velocity of the centrifugal fan, v2 is the air fluid outflow velocity of the centrifugal fan, S1 is the control surface area on the left side of the control body, and S2 is the control surface area on the right side of the control body.

[0015] Preferably, the fluid momentum equation is introduced into the flow analysis process of the air fluid in the negative pressure chamber to obtain the momentum change rate of the air fluid, which includes the following steps:

[0016] Based on Newton's second law, the formula for the rate of change of momentum of the air fluid in the negative pressure chamber is derived;

[0017] The rate of change of momentum of the air fluid is as follows:

[0018]

[0019] Where ρ is the air density under standard atmospheric pressure, V is the volume of air fluid, v is the air fluid velocity, S is the surface area of ​​the control surface, and p is x is the initial pressure of the air in the negative pressure chamber, and dx is the displacement of the fluid system in the x direction.

[0020] Preferably, the second expression is as follows:

[0021]

[0022] Where ρ is the air density at standard atmospheric pressure.

[0023] Preferably, in the process of analyzing the flow of air fluid in the fluid channel of the sealing device, a differential equation group is established, and the differential equation group is deduced and replaced in magnitude to obtain the fluid channel pressure difference formula, which includes the following steps:

[0024] According to the boundary layer microelement analysis method, the continuity equation and NS equation are used to establish the boundary layer differential equation group of the fluid channel;

[0025] The pressure difference formula of the fluid channel is obtained by deriving and equivalently replacing the equations in the fluid channel boundary layer differential equation group.

[0026] Preferably, the negative pressure adsorption force of the wall-climbing robot is as follows:

[0027]

[0028] Where F is the negative pressure adsorption force, Δρ is the pressure difference between the inside and outside of the negative pressure device, r0 is the radius of the negative pressure cavity, d is the length of the fluid channel of the sealing device, μ is the fluid dynamic viscosity, and v0 is the mainstream velocity of the air fluid in the leakage channel.

[0029] A negative pressure adsorption force calculation device for a wall-climbing robot generates negative pressure adsorption force through a negative pressure adsorption device, comprising:

[0030] An analysis module is used to analyze the overall flow process of the air fluid in the negative pressure adsorption device of the wall-climbing robot to obtain a first expression for characterizing the motion state of the air fluid; the negative pressure adsorption device includes a negative pressure chamber, a centrifugal fan and a sealing device;

[0031] An introduction module is used to introduce a fluid momentum equation during the flow analysis of the air fluid in the negative pressure chamber to obtain the momentum change rate of the air fluid; the momentum change rate of the air fluid is transformed and combined with the first expression to obtain a second expression for characterizing the negative pressure adsorption force and the air fluid velocity;

[0032] Establishing a module for establishing a differential equation group in the process of analyzing the flow of air fluid in the fluid channel of the sealing device, deriving and replacing the differential equation group, and obtaining a pressure difference formula of the fluid channel;

[0033] The calculation module is used to transform the second expression and substitute it into the fluid channel pressure difference formula to obtain the negative pressure adsorption force during the movement of the wall-climbing robot.

[0034] A computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the negative pressure adsorption force calculation method of the wall-climbing robot when executing the program.

[0035] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the negative pressure adsorption force calculation method of the wall-climbing robot is implemented.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The present invention first analyzes the overall flow process of the air fluid in the negative pressure adsorption device of the wall-climbing robot, and obtains a first expression for characterizing the motion state of the air fluid. At the same time, the fluid momentum equation is introduced in the flow analysis process of the air fluid in the negative pressure chamber, and a second expression for characterizing the negative pressure adsorption force and the air fluid velocity is obtained. In the flow analysis process of the air fluid in the fluid channel of the sealing device, a differential equation group is established to obtain the fluid channel pressure difference formula, and finally the second expression is deformed and substituted into the fluid channel pressure difference formula to obtain the negative pressure adsorption force during the movement of the wall-climbing robot. Based on the basic theoretical foundations of fluid mechanics and aerodynamics, the present invention deeply analyzes the motion state of the air fluid during the movement of the wall-climbing robot, and introduces the fluid momentum equation to obtain the relationship between the negative pressure adsorption force and the air fluid velocity. Different derivation methods are used to finally obtain the calculation formula for the negative pressure adsorption force of the wall-climbing robot applied to the composite wellbore structure. The calculation result is accurate, the parameter selection is standard, and the overall calculation amount is not large, and it can be directly applied and converted. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 It is a schematic diagram of the gas flow process of the negative pressure chamber control body of the present invention;

[0040] Figure 2 It is a schematic diagram of the gas flow process of the centrifugal fan control body of the present invention;

[0041] Figure 3 It is a schematic diagram of force analysis of the negative pressure chamber control body of the present invention;

[0042] Figure 4 It is a schematic diagram of the momentum flow of the negative pressure chamber control body of the present invention;

[0043] Figure 5 A schematic diagram of a sealing device for a wall-climbing robot according to the present invention;

[0044] Figure 6 A schematic diagram of the formation and development of the leakage channel boundary layer of the present invention;

[0045] Figure 7 It is a schematic flow chart of the method for calculating the negative pressure adsorption force of the wall-climbing robot of the present invention. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] Reference Figure 7 , a method for calculating the negative pressure adsorption force of a wall-climbing robot, comprising the following steps:

[0048] The first step is to analyze the overall flow process of the air fluid in the negative pressure adsorption device of the wall-climbing robot to obtain a first expression for characterizing the motion state of the air fluid.

[0049] The negative pressure adsorption system of the wall-climbing robot follows the basic principles of fluid mechanics and aerodynamics, as well as the laws of thermodynamics, Newton's laws of mechanics, energy conversion and conservation, and other basic laws. As the object of the negative pressure adsorption system research, the fluid properties and flow laws of the gas in the working environment of the wall-climbing robot, as well as the changes in the characteristic parameters and motion states of the gas at different stages during the negative pressure adsorption process, are the focus of the negative pressure adsorption fluid state analysis.

[0050] The process of negative pressure adsorption device of wall-climbing robot generating negative pressure adsorption force consists of two continuous fluid movement stages. One is the stage in which the static air in the negative pressure chamber generates lateral flow under the action of the suction force of the centrifugal fan, and then the gas leaked from the sealing device is supplemented into the negative pressure chamber to finally reach flow balance. The other is the stage in which the centrifugal fan drives the incoming air to rotate at high speed, and then the centrifugal force throws the air out of the impeller and discharges it from the outlet. The two stages are both interconnected and independent of each other. In fluid state analysis, they can be used as two control body analysis processes and analyzed independently. During the entire air flow process, limited by the volume of the negative pressure chamber and the suction force of the centrifugal fan, the temperature and pressure of the air participating in the flow do not change much, and it can be regarded as a complete gas for analysis. The overall flow rate of the air fluid is not high during the process, and the average air flow velocity does not exceed 0.3Ma. The gas density does not change with time, that is, dρ / dt=0. Without considering the change of specific volume, the fluid air can be considered as an incompressible gas. The gas state parameters in the negative pressure chamber during the process only change with the change of the movement position and the fan speed, and have no linear relationship with the process time. The flow of the air fluid can be considered as a steady flow. There is no external heat source contacting the fluid during the process, and there is no heat exchange inside the air fluid in the closed space. The increase in the temperature of the gas at the air outlet is caused by the work done by the centrifugal fan impeller on the air. The flow of the air fluid can be considered as an adiabatic flow. During the process, the gas movement is mainly affected by inertia and surface forces, and the air gravity does not play a major role. In order to facilitate the calculation of the extensiveness and intensity of the air fluid, the influence of gravity on the fluid flow is ignored, and the air fluid is regarded as a non-gravity fluid for analysis.

[0051] like Figure 1 In the initial static state, the gas density T1, pressure P1 and temperature in the negative pressure chamber of the adsorption device are the same as the gas density T0, pressure P0 and temperature of the atmosphere outside the negative pressure chamber, that is, P1 = P0, T1 = T0, and the negative pressure chamber control body KT q The volume V q Equal to the actual gas volume of the negative pressure chamber. At time t0, the centrifugal fan at the rear end of the negative pressure chamber begins to rotate, generating a lateral suction force that transports the air in the chamber toward the centrifugal fan, causing the state of the original air system in the chamber to change. According to Clapeyron's ideal gas state equation:

[0052]

[0053] Where: m is the mass of the gas, kg; M is the molar mass of the gas, M = 28.9634 g / m; R is the universal gas constant, R = 8.314 J / (K·mol).

[0054] From the equation, we can know that at the moment when the centrifugal fan rotates, the negative pressure chamber control body KT qThe air inside starts to flow. Part of the air moves towards the centrifugal fan through the control surface KM2. The gas loss causes the quality of the original air system to decline. Since the volume of the negative pressure chamber remains unchanged and the air temperature remains unchanged, the gas pressure inside the chamber decreases. At this time, P1 < P0, and a negative pressure is generated inside the negative pressure chamber, forming a negative pressure adsorption force. At time t1, due to the internal and external pressure difference, external air leaks into the negative pressure chamber from the bottom of the sealing device and enters the negative pressure chamber through the control surface KM1 to supplement the air loss in the control volume. The leaked air merges with the air inside the chamber. Without change in density and temperature, the pressure of the leaked gas decreases. At this time, the equal pressure inside the chamber is in a constantly fluctuating process. With the continuous entry of the leaked gas, by time t2, the flow rate of the leaked air is the same as the suction volume of the centrifugal fan, and the inflow and outflow of the air fluid through the control volume reach equilibrium. The fluid system is in an equilibrium state, and the equal pressure inside the chamber tends to be stable but is still less than P0, and the negative pressure adsorption force reaches a fixed value.

[0055] During the fluid movement of the centrifugal fan, as Figure 2 , the air sucked by the centrifugal fan has a pressure and temperature of P1 and T1 respectively before entering the centrifugal fan. After entering, the air is driven by the centrifugal fan impeller to rotate at high speed, and the gas flow direction changes from axial to radial. During this process, due to gas viscous friction, gas resistance is generated. The centrifugal fan compresses and does work on the air, and part of the mechanical energy is converted into gas internal energy, causing the gas temperature to rise and the pressure to increase, and generating a certain amount of aerodynamic noise. In fact, it is a process of entropy increase in an adiabatic system. At this time, the air pressure and temperature become P2 and T2, and P1 < P2, T1 < T2. The gas density ρ remains unchanged. When the gas flows out of the air outlet, it quickly merges with the external atmosphere, and the gas parameters return to the standard atmospheric parameters. Due to the limited air outlet volume, the outlet gas will not affect the gas parameters of the air around the wall-climbing robot.

[0056] Suppose there is an air fluid system N. At time t0, the fluid system N coincides with the control volume KT L and has the same shape and volume. At time t1, it moves to a new position and is composed of parts ② and ③ in the figure. The position and volume of the control volume remain unchanged and are composed of parts ① and ② in the figure. Part ① is the air fluid that flows into the control volume from the left control surface KM1 of the control volume during the time period from t0 to t1, and part ③ is the air fluid that flows out of the control volume from the right control surface KM2 of the control volume during the time period from t0 to t1. At this time, the shape and volume of the fluid system have changed. Let an extensive quantity function of the fluid system be:

[0057]

[0058] At time t0, the fluid system N coincides with the control volume KT L , then there is: N(t) = N KTL(t). At time t1, according to the Reynolds transport theorem, the rate of change of the total physical quantity in a variable volume fluid system at a certain time is equal to the sum of the rate of change of the physical quantity in the control body of the same shape and volume at that time and the flux transported through the control body interface. According to the Reynolds transport equation:

[0059]

[0060] Where:

[0061]

[0062] Where: dV1 = -v1δtdS1, v1 is the gas inflow velocity, m / s; S1 is the area of ​​the inflow control surface KM1, m 2 .

[0063]

[0064] Where: dV2 = -v2δtdS2, v2 is the gas outflow velocity, m / s; S2 is the area of ​​the outflow control surface KM2, m 2 .

[0065] Substituting equation (4), equation (5) and equation (6) into equation (3), we have:

[0066]

[0067] For a steady flow field, when the fluid system coincides with the control body, the change in the system's extensiveness depends only on the flow on the control surface and has nothing to do with the flow in the control body. The above formula can be changed to:

[0068]

[0069] Formula (8) is the first expression, from which we can know that in the process of fluid movement in the centrifugal fan, when the inflow and outflow control surface areas are constant, the mass and internal energy of the air fluid and other extensive quantities are related to the speed at which the fluid flows into and out of the control body.

[0070] Step 2: Introduce the fluid momentum equation during the flow analysis of the air fluid in the negative pressure chamber to obtain the momentum change rate of the air fluid.

[0071] The movement process of air fluid in the negative pressure cavity is a process from static to flowing and then to stable. In this process, the air fluid system is affected by the external force of the system, has mass exchange with the outside of the system, and its own pressure also changes. In order to analyze the functional relationship between the fluid state and the motion parameters during the movement process, the fluid momentum equation is introduced, and the analysis is carried out based on Newton's second law and the derived Reynolds transport equation.

[0072] According to Newton's second law, the rate of change of momentum of a fluid system is equal to the vector sum of all external forces acting on the fluid:

[0073]

[0074] like Figure 3 and Figure 4 In the initial and stable stages of the flow process, the air fluid in the negative pressure chamber control body is only subject to the suction force from the centrifugal fan in the x direction. There is no other surface force acting on the fluid in the y and z directions. The influence of mass force on the flow process is ignored. According to the diagram, the vector sum of the surface forces acting on the control surface of the control body is the difference between the surface forces on the left and right control surfaces. According to the relationship between force, pressure and force area, the momentum change rate of the fluid system can be expressed as:

[0075]

[0076] Where: S is the surface area of ​​the control surface; dx is the displacement of the fluid system in the x direction, m; is the change in pressure in the cavity during the process, Pa; - means that the surface force on the fluid system in the x direction is an outward suction force, not an inward squeezing force.

[0077] According to the Reynolds transport equation (8) derived in the previous section, the momentum change rate of the fluid system can be expressed as:

[0078]

[0079] The air fluid flow is a steady flow. Discarding the change in fluid momentum in the control body, combining equations (10) and (11), we get:

[0080]

[0081] Where: V = dxS. Taking the limit of the above formula, we have:

[0082]

[0083] Formula (13) is the second expression. It can be seen from the second expression that when the air fluid flows in the negative pressure chamber, the drop in the gas pressure in the chamber has a functional relationship with the fluid velocity. The faster the air fluid velocity, the greater the system negative pressure value.

[0084] According to equations (10) and (12), another way to calculate the suction force of a centrifugal fan can be obtained:

[0085]

[0086] In the above formula, the fluid velocity v is the final velocity of the fluid in the adjacent time during the process from static to flowing, and is the relative average velocity of the fluid flow in the stable flow stage.

[0087] Based on the momentum moment equation, the fluid motion process of the air flowing in the centrifugal fan control body is analyzed, and the momentum moment balance equation of the fluid system is obtained.

[0088] The movement of the air fluid in the negative pressure chamber belongs to the horizontal flow movement. Under the action of the single-phase external force, the fluid system moves in a fixed straight direction, and the movement angle remains unchanged during the movement. The momentum equation analysis method can accurately describe the state change process of the fluid center of mass following the movement of the fluid system. However, in the analysis of the fluid system of the centrifugal fan control body, since the air fluid is directly affected by the mechanical external force of the fan impeller during this process, it performs high-speed rotation in the control body. During this period, not only the flow direction has changed, but the movement speed is no longer a single speed direction. The internal energy of the system also increases due to mechanical work. The momentum equation analysis method cannot describe the movement law of the rotating fluid system rotating around the fixed center of mass. Based on the momentum theorem, the momentum moment theorem more accurately reflects the relationship between the momentum moment of the particle system and the impulse moment of the particle system under mechanical action. The momentum moment equation can be used to derive the basic equation of the centrifugal fan control body, solve the problem of mechanical and fluid energy conversion, and determine the position of the force between the air fluid and the impeller. It is suitable for the analysis of the air fluid movement process of the centrifugal fan control body of the present invention.

[0089] The vector sum of the momentum of a single particle in a fluid system with respect to the center is called the momentum moment of the particle with respect to the center. When the air fluid enters the centrifugal fan, the single air particle rotating with the fluid system generates a momentum moment with respect to the center of the fan (the center). The rate of change of the momentum moment of the particle per unit time is:

[0090]

[0091] In the formula: m is the mass of the particle, kg; v is the velocity of the particle, m / s; r is the radius of the particle from the center, m; F is the resultant external force on the particle, N.

[0092] According to the momentum theorem: the time rate of change of the momentum of the fluid in the fluid system about a certain point is equal to the vector sum of the moments of all external forces acting on the system at the same point. For the air fluid system, we have:

[0093]

[0094] The momentum of the fluid system is a vector quantity, which belongs to the fluid extension quantity. Based on this, substituting equation (16) into the Reynolds transport equation (8), we get:

[0095]

[0096] It is equivalent to assuming that the number of impellers on the centrifugal fan is sufficient, and the air fluid flows steadily in the centrifugal fan control body. The influence of the fluid mass force and the air internal friction on the fluid momentum moment is ignored. Combining equations (16) and (17), the momentum moment balance equation of the centrifugal fan control body air fluid system is established:

[0097]

[0098] In the centrifugal fan control body KT L Inside, r1 is the inner diameter of the fan, and the circle enclosed by r1 as the radius is the fluid inflow control surface KM1, r2 is the outer diameter of the fan, and the circle enclosed by r2 as the radius is the fluid outflow control surface KM2. When the air fluid flows in the rotating body coordinate system, it first flows in from the inner ring, moves along the fan blade flow channel, and then flows out from the outer ring. During this period, the fan impeller drives the fluid to rotate counterclockwise at a constant angular velocity ω. The motion state and direction of the fluid change under the direct action of the mechanical external force of the impeller device, and the fluid velocity produces components in different directions. On the one hand, the fluid moves along the tangent direction of the blade curvature, generating a relative velocity v r On the one hand, the fluid moves along the tangent direction of the inner and outer rings, generating a drag velocity v e , and the fluid velocity can also be decomposed into the normal velocity v corresponding to the radius vector n and the tangential velocity v τ , the subscript 1 is the velocity component when the fluid flows into the control body, and the subscript 2 is the velocity component when the fluid flows out of the control body. The relationship between the absolute velocity of the fluid and each component is:

[0099]

[0100] Use the normal velocity v corresponding to the radius vector n and the tangential velocity v τ are the two velocity components of the absolute velocity v, substituted into the derived momentum balance equation of the fluid system:

[0101]

[0102] Where: v2cosɑ2=v 2τ , v1cosɑ1=v 1τ , S2 is the area of ​​outflow control surface KM2, m 2 ; S1 is the area of ​​the inflow control surface KM1, m 2 .

[0103] When the air fluid system reaches a state of equilibrium, the gas flow rate flowing into the control body is equal to the gas flow rate flowing out. According to the fluid flow equation Q = ρv n A, we can get the functional expression of the velocity component in the normal direction when the fluid flows into and out of the control volume:

[0104]

[0105] According to formula (21), the momentum balance equation of the fluid system can be changed into:

[0106] ρr2v 2t v 2n S2-ρe1v 1t v 1n S1=Q v (r2v 2r -r1v 1r )=∑(r×F) (22)

[0107] In the negative pressure device, the total torque transmitted by the motor to the impeller is MZ = ∑(r × F). According to formula (22), the flow rate expression of the total torque can be derived:

[0108] M z =Q v (r2v 2r -r1v 1t ) (twenty three)

[0109] According to the power equation of the rotating body drive shaft and the acceleration synthesis theorem, the power exerted by the centrifugal fan impeller on the air fluid system is:

[0110] P=M z ω=Q v ω(r2v 2r -r1v 1τ )=Q v (v 2e v 2t -v 1e v 1τ ) (twenty four)

[0111] It can be seen from formula (24) that when the air fluid flows in the centrifugal fan, the negative pressure system power has a functional relationship with the inflow and outflow speeds of the air fluid, and the system power value is determined by the speed difference.

[0112] Step 3: Establish a differential equation group during the flow analysis of the air fluid in the fluid channel of the sealing device, derive and replace the differential equation group, and obtain the fluid channel pressure difference formula.

[0113] The negative pressure adsorption device of the wall-climbing robot, in addition to the negative pressure chamber and the centrifugal fan, also has an important functional component, namely the sealing device. On the one hand, the sealing device must ensure good sealing, achieve limited leakage of air fluid, maintain the pressure difference between the gas in the negative pressure chamber and the outside atmosphere, so that the robot can obtain continuous and stable negative pressure adsorption force; on the other hand, it must also be strong and wear-resistant, have a small friction coefficient, and adopt a flexible design to effectively fill the tiny grooves and protrusions on the rough well wall, reduce the friction between the device and the well wall surface, and reduce the robot's movement resistance.

[0114] Under the action of the internal and external pressure difference, the external air enters the negative pressure chamber from the annular sealing device at the bottom of the negative pressure device. Figure 5 From the structural cross-section, it can be simplified as parallel plate gap flow, forming a flow channel with a length of d and a height of h between the sealing device and the wall. During the air leakage process, the channel is filled with flowing air, which can be roughly understood as adding a transition layer with almost no friction between the sealing device and the wall, so that the sealing device and the wall are not in direct contact, and no positive pressure is formed between the two, thereby improving the friction performance of the robot motion system. Here, the height of the channel h is an important parameter affecting the stability of the negative pressure device and the flexibility of the robot movement. It needs to be within a reasonable range. If h is too high, the external air leakage will be too large, increasing the air pressure in the negative pressure chamber, reducing the pressure difference between the inside and outside of the device, and the negative pressure adsorption force will decrease, and the robot will be in a dangerous state of slipping. If h is too low, the friction between the sealing device and the wall will increase, forming dry friction, increasing component wear, reducing service life, increasing the movement resistance of the wall-climbing robot, affecting the movement flexibility, and increasing power loss.

[0115] According to the principles of aerodynamics and Prandtl boundary layer theory, when leaking air passes through the fluid channel, it is affected by the viscous force of the fluid, and the air fluid produces a certain velocity gradient on the well wall and the surface of the sealing device to form a boundary layer. Inside the boundary layer, the fluid viscosity is greater than the fluid inertia force. Along the normal direction of the channel wall surface, the fluid velocity increases from zero to the normal velocity of the fluid, and then reaches the outer edge of the boundary layer. The normal height is the boundary layer thickness. Outside the boundary layer is the outflow area. The fluid in the outflow area is not blocked by the wall. Ignoring the influence of the fluid viscosity, the flow velocity returns to the mainstream flow velocity, which is regarded as an ideal fluid steady flow state.

[0116] According to the flow state of the fluid in the boundary layer, the boundary layer can be divided into laminar boundary layer and turbulent boundary layer, which are judged by Reynolds number. Reynolds number represents the ratio of migration inertia force to viscous force. It is a dimensionless number that can be used to characterize the flow of fluid. When the Reynolds number is small, the viscous force formed between the fluid and the wall in the boundary layer is greater than the influence of the fluid inertia force brought by the fluid velocity on the fluid state, and the air fluid state in the boundary layer is stable. On the contrary, when the Reynolds number is large, the influence of the fluid inertia force is greater than the influence of the fluid viscosity on the fluid state, and the air fluid state in the boundary layer is unstable, forming a turbulent and irregular turbulent flow field. Under normal circumstances, the air fluid has a low viscosity to the wall and a fixed viscosity coefficient, so the mainstream velocity of the fluid has a greater influence on the flow state of the fluid in the boundary layer. The faster the mainstream velocity of the fluid, the larger the Reynolds number, and the slower the mainstream velocity of the fluid, the smaller the Reynolds number.

[0117] The pressure difference between the inside and outside of the negative pressure chamber is small, the speed of the centrifugal fan is not high, the fluid leakage of the sealing device is not large, and the height of the fluid channel is very small. The mainstream speed of the air fluid is very slow, not exceeding 0.3-100m / s, and the Reynolds number of the fluid flow does not exceed 200, which is a small Reynolds number flow. The gas flow in the boundary layer will not cause airflow obstruction. The critical Reynolds number of laminar and turbulent flow in the internal flow field is 2000, so the boundary layer in the leakage channel of the wall-climbing robot is a laminar boundary layer. Figure 6 , external air enters the fluid channel, and at the entrance of the channel, the no-slip condition on the wall causes the flow layers on the upper and lower walls of the channel to stagnate, and a boundary layer begins to form. The fluid velocity slows down in the boundary layer area, and the fluid velocity in the outer flow area remains unchanged. With the continuous influx of air fluid, the thickness of the boundary layer continues to increase. At a certain node, the upper and lower boundary layers converge, the outer flow area disappears, and the entire channel is filled with the boundary layer until the end of the channel. The air fluid passes through the channel into the negative pressure cavity. Based on this, the flow in the channel can be divided into two regions, one is the region before the upper and lower boundary layers converge, called the entrance section region, and the other is the region after the upper and lower boundary layers converge, called the development section region. Since the incoming air fluid velocity is small, the boundary layer flows in laminar form when it converges in the center of the channel, and the air flow in the channel continues to maintain a laminar state.

[0118] After the air fluid enters the negative pressure chamber through the fluid channel, its density, temperature and volume do not change. Only the gas pressure decreases linearly with the channel length during the flow process. Ignoring the influence of mass force, the fluid motion in the channel boundary layer is a two-dimensional steady flow of incompressible viscous fluid. According to the boundary layer microelement analysis method proposed by Prandtl and von Karman, the continuity equation and NS equation can be used to establish the differential equation:

[0119]

[0120] In equation (25), v is the mainstream velocity of air fluid, m / s; v xand v y It represents the velocity components of the mainstream velocity in the lateral and vertical directions of the channel, The change of is from 0 to the channel length d,m; The change of is from 0 to 1 / 2 of the channel height h. According to the first equation of the equation group, we have:

[0121]

[0122] The mainstream speed of air fluid is very slow, and the Reynolds number of fluid flow in the boundary layer is very small. When comparing magnitudes and replacing traces, 1 / Re cannot be considered to be close to 0 as when analyzing high-speed flowing fluids. Similarly, due to the short length of the sealing device, the air fluid flows in laminar flow in the boundary layer, and the ratio of channel height to channel length h / d cannot be considered a trace. According to the second equation of the equation group, the change in gas pressure during the fluid passing through the channel can be deduced as:

[0123]

[0124] In the boundary layer, the velocity component v x The thickness along the boundary normal gradually increases from 0 to v, which can be equivalent to v x →v, Velocity component v y The magnitude can be replaced by formula (26):

[0125]

[0126] According to the flat plate boundary layer thickness equation, the relationship equation between channel length and channel thickness can be derived:

[0127]

[0128] Where: μ is the dynamic viscosity of the fluid, Pa·s; under standard atmospheric pressure and temperature of 20°C, the dynamic viscosity of air is 17.9×10 -6 Pa·s.

[0129] Comparing the magnitude and substituting the third equation in the system of equations, we can get During the gas flow, there is no pressure change in the normal direction of the boundary layer. The gas pressure only produces a pressure difference in the tangential direction of the boundary layer. Substituting the results derived from equations (28) and (29) into equation (27), the pressure difference formula of the liquid channel can be obtained:

[0130]

[0131] Step 4: Transform the second expression and substitute it into the fluid channel pressure difference formula to obtain the negative pressure adsorption force during the movement of the wall-climbing robot.

[0132] According to the conclusion obtained from the analysis of the momentum change rate during the movement of the fluid in the negative pressure chamber, the change in the gas pressure in the negative pressure chamber can be obtained by transforming equation (13):

[0133] Δp=ρv 2 (31)

[0134] The causes and mechanisms of the pressure difference between the negative pressure chamber of the negative pressure device and the pressure difference between the inside and outside of the sealing device channel are different, and the pressure gradients are different. When the centrifugal fan is started, the air flowing into the sealing device and the original air will have a more complicated fusion process in the negative pressure chamber. When the fluid state in the negative pressure chamber tends to be stable, the pressure difference between the inside and outside of the sealing device is equal to the pressure difference between the inside and outside of the negative pressure chamber:

[0135]

[0136] Where: v0 is the mainstream velocity of the air fluid in the leakage channel, m / s; v1 is the initial velocity of the air fluid flowing into the centrifugal fan in the negative pressure chamber, m / s; According to the pressure formula, the negative pressure adsorption force provided by the negative pressure device to the wall-climbing robot is:

[0137]

[0138] It can be seen from formula (33) that during the operation of the negative pressure adsorption device, the output negative pressure adsorption force has a functional relationship with the radius of the negative pressure chamber, the length of the sealing device, and the flow velocity of the air fluid in the fluid channel and the negative pressure chamber. When the structure of the negative pressure adsorption device is fixed, the negative pressure adsorption force is determined by the air fluid velocity.

[0139] Based on the same concept, the present invention also provides a negative pressure adsorption force calculation device for a wall-climbing robot, comprising an analysis module, an introduction module, a building module and a calculation module.

[0140] The analysis module is used to analyze the overall flow process of the air fluid in the negative pressure adsorption device of the wall-climbing robot to obtain a first expression for characterizing the motion state of the air fluid; the negative pressure adsorption device includes a negative pressure chamber, a centrifugal fan and a sealing device.

[0141] The introduction module is used to introduce the fluid momentum equation during the flow analysis of the air fluid in the negative pressure chamber to obtain the momentum change rate of the air fluid; the momentum change rate of the air fluid is transformed and combined with the first expression to obtain a second expression for characterizing the negative pressure adsorption force and the air fluid velocity.

[0142] The module is used to establish a differential equation group in the flow analysis process of air fluid in the fluid channel of the sealing device, derive and replace the differential equation group, and obtain the fluid channel pressure difference formula.

[0143] The calculation module is used to transform the second expression and substitute it into the fluid channel pressure difference formula to obtain the negative pressure adsorption force during the movement of the wall-climbing robot.

[0144] The present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the above-mentioned method for calculating the negative pressure adsorption force of the wall-climbing robot is implemented.

[0145] The present invention also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the above-mentioned method for calculating the negative pressure adsorption force of the wall-climbing robot is implemented.

[0146] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0147] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for calculating the negative pressure adsorption force of a wall-climbing robot, characterized in that: The negative pressure adsorption force is generated by the negative pressure adsorption device, including the following steps: The overall flow process of air fluid in a negative pressure adsorption device of a wall-climbing robot is analyzed to obtain a first expression for characterizing the motion state of the air fluid; the negative pressure adsorption device includes a negative pressure chamber, a centrifugal fan and a sealing device; In the process of analyzing the flow of air fluid in the negative pressure chamber, a fluid momentum equation is introduced to obtain the momentum change rate of the air fluid; the momentum change rate of the air fluid is transformed and combined with the first expression to obtain a second expression for characterizing the negative pressure adsorption force and the air fluid velocity; In the process of analyzing the flow of air fluid in the fluid channel of the sealing device, a differential equation group is established, and the differential equation group is derived and replaced in magnitude to obtain a pressure difference formula of the fluid channel; The second expression is transformed and substituted into the fluid channel pressure difference formula to obtain the negative pressure adsorption force during the movement of the wall-climbing robot; The first expression is as follows: Where N(t) is the extensive function of the fluid system, KM1 is the control surface on the left side of the control body, and KM2 is the control surface on the right side of the control body. is the rate of change of the total physical quantity with time t, v1 is the air fluid inflow velocity of the centrifugal fan, v2 is the air fluid outflow velocity of the centrifugal fan, S1 is the control surface area on the left side of the control body, and S2 is the control surface area on the right side of the control body; In the process of analyzing the flow of air fluid in the negative pressure chamber, the fluid momentum equation is introduced to obtain the momentum change rate of the air fluid, including the following steps: Based on Newton's second law, the formula for the rate of change of momentum of the air fluid in the negative pressure chamber is derived; The rate of change of momentum of the air fluid is as follows: Where ρ is the air density under standard atmospheric pressure, V is the volume of air fluid, v is the air fluid velocity, S is the surface area of ​​the control surface, and p is x is the initial pressure of the air in the negative pressure chamber, dx is the displacement of the fluid system in the x direction; The second expression is as follows: Where ρ is the air density at standard atmospheric pressure.

2. A method for calculating negative pressure adsorption force of a wall-climbing robot as claimed in claim 1, characterized in that: The overall flow process of the air fluid includes a first stage and a second stage, wherein the first stage is that the static air fluid in the negative pressure chamber is subjected to the suction force of the centrifugal fan to produce lateral flow, and then the gas leaked from the sealing device is supplemented into the negative pressure chamber to finally achieve flow balance, and the second stage is that the centrifugal fan drives the air fluid to rotate at a high speed, and then the centrifugal force throws the air out of the impeller and discharges it from the outlet.

3. A method for calculating negative pressure adsorption force of a wall-climbing robot as claimed in claim 1, characterized in that: In the process of analyzing the flow of air fluid in the fluid channel of the sealing device, a differential equation group is established, and the differential equation group is deduced and replaced in magnitude to obtain the fluid channel pressure difference formula, including the following steps: According to the boundary layer microelement analysis method, the continuity equation and NS equation are used to establish the boundary layer differential equation group of the fluid channel; The pressure difference formula of the fluid channel is obtained by deriving and equivalently replacing the equations in the fluid channel boundary layer differential equation group.

4. A method for calculating negative pressure adsorption force of a wall-climbing robot as claimed in claim 3, characterized in that: The negative pressure adsorption force of the wall-climbing robot is as follows: Where F is the negative pressure adsorption force, Δρ is the pressure difference between the inside and outside of the negative pressure device, r0 is the radius of the negative pressure cavity, d is the length of the fluid channel of the sealing device, μ is the fluid dynamic viscosity, and v0 is the mainstream velocity of the air fluid in the leakage channel.

5. A negative pressure adsorption force calculation device for a wall-climbing robot, characterized in that: The negative pressure adsorption force is generated by the negative pressure adsorption device, including: An analysis module is used to analyze the overall flow process of the air fluid in the negative pressure adsorption device of the wall-climbing robot to obtain a first expression for characterizing the motion state of the air fluid; the negative pressure adsorption device includes a negative pressure chamber, a centrifugal fan and a sealing device; An introduction module is used to introduce a fluid momentum equation during the flow analysis of the air fluid in the negative pressure chamber to obtain the momentum change rate of the air fluid; the momentum change rate of the air fluid is transformed and combined with the first expression to obtain a second expression for characterizing the negative pressure adsorption force and the air fluid velocity; Establishing a module for establishing a differential equation group in the process of analyzing the flow of air fluid in the fluid channel of the sealing device, deriving and replacing the differential equation group, and obtaining a pressure difference formula of the fluid channel; A calculation module is used to transform the second expression and substitute it into the pressure difference formula of the fluid channel to obtain the negative pressure adsorption force during the movement of the wall-climbing robot; The first expression is as follows: Where N(t) is the extensive function of the fluid system, KM1 is the control surface on the left side of the control body, and KM2 is the control surface on the right side of the control body. is the rate of change of the total physical quantity with time t, v1 is the air fluid inflow velocity of the centrifugal fan, v2 is the air fluid outflow velocity of the centrifugal fan, S1 is the control surface area on the left side of the control body, and S2 is the control surface area on the right side of the control body; In the process of analyzing the flow of air fluid in the negative pressure chamber, the fluid momentum equation is introduced to obtain the momentum change rate of the air fluid, including the following steps: Based on Newton's second law, the formula for the rate of change of momentum of the air fluid in the negative pressure chamber is derived; The rate of change of momentum of the air fluid is as follows: Where ρ is the air density under standard atmospheric pressure, V is the volume of air fluid, v is the air fluid velocity, S is the surface area of ​​the control surface, and p is x is the initial pressure of the air in the negative pressure chamber, dx is the displacement of the fluid system in the x direction; The second expression is as follows: Where ρ is the air density at standard atmospheric pressure.

6. A computer device, characterized in that: It includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the method for calculating the negative pressure adsorption force of a wall-climbing robot described in any one of claims 1 to 4 is implemented.

7. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, and when the computer program is executed by the processor, the method for calculating the negative pressure adsorption force of the wall-climbing robot described in any one of claims 1 to 4 is implemented.

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