Insulator surface dirt cleaning method based on flexible pneumatic hoop mechanism

Abstract

The invention discloses an insulator surface dirt cleaning method based on a flexible pneumatic hoop mechanism. Comprising the following steps: based on the working process and principle of an air bag structure, performing mathematical modeling on the air pressure and bending angle of a single air bag to provide a theoretical basis for the research of a subsequent air pressure control strategy; based on a flexible pneumatic hoop mechanism model, a mechanism control strategy combining rapid inflation and deflation and slow pulse inflation and deflation capable of accurately controlling the air pressure change of an air bag is provided according to the requirement for mechanism bending motion in the insulator holding process, and compliant control over the insulator holding process is achieved. According to the insulator surface dirt cleaning method based on the flexible pneumatic hoop mechanism, a flexible pneumatic hoop mechanism control method capable of completing an insulator holding task is designed, combination of rapid inflation and deflation and slow pulse inflation and deflation for accurately controlling air pressure change of an air bag can be achieved, and smooth control over the insulator holding process is achieved.

Description

Technical Field

[0001] The invention relates to an insulator cleaning mechanism, in particular to a method for cleaning dirt on the surface of an insulator based on a flexible pneumatic clamp mechanism, and belongs to the technical field of power equipment. Background Art

[0002] Insulators are specialized insulating components used to secure live conductors in power transmission lines. Because insulators are exposed to ambient conditions for extended periods during operation, dust particles from the surrounding atmosphere easily adhere to their surfaces, forming a contamination layer. Currently, manual scrubbing is a common method for cleaning and maintaining insulators, but this approach is labor-intensive and inefficient. Recent research has explored the application of robotic arms and other devices for insulator surface cleaning. However, most cleaning mechanisms are rigid, with limited ability to clean insulators of varying outer diameters.

[0003] As one of the design options for flexible mechanisms, the pneumatic system's structural design and airbag pressure control are very important. Precise pressure control directly affects the performance of the robot. Currently, pneumatic systems based on a combination of pumps and solenoid valves are widely used. The pump serves as the air source, and the solenoid valve is used to control the open / close state of the air passage. However, most pneumatic systems are designed to provide only a single pressure state, positive or negative. Moreover, during the inflation and deflation process, due to the limitations of the pneumatic design and the discrete on / off characteristics of the valve, the air pressure drops sharply, making it difficult to achieve precise and smooth pressure control.

[0004] Therefore, it is of great significance to design a method for cleaning insulator surface dirt based on a flexible pneumatic clamp mechanism for insulator cleaning. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for cleaning dirt on the surface of an insulator based on a flexible pneumatic clamp mechanism, so as to achieve smooth control of the insulator clamping process and clean insulators with different outer diameters.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A method for cleaning contamination from insulator surfaces based on a flexible pneumatic clamp mechanism is proposed. The flexible pneumatic clamp mechanism, consisting of multiple airbags, an air pump, and a solenoid valve, is analyzed. A mathematical model of the airbag bending is established. Based on the system configuration and different working processes, an inflation and deflation strategy and mechanism control method are proposed, achieving smooth control of the insulator clamping process.

[0008] The following steps are involved:

[0009] Step S1: Based on the flexible pneumatic clamp mechanism that completes the insulator clamping task, the working process and principle of the airbag structure are analyzed, and the airbag pressure and bending angle are mathematically modeled;

[0010] Step S2: Based on the flexible pneumatic clamp mechanism model, in view of the requirement for the bending movement of the mechanism during the process of clamping the insulator, a mechanism control strategy combining rapid inflation and deflation with slow pulse inflation and deflation is proposed to accurately control the change of airbag pressure, thereby achieving smooth control of the insulator clamping process.

[0011] The purpose of the present invention can be further achieved by the following technical measures:

[0012] The step S1 mathematically models the airbag pressure and bending angle as follows:

[0013] In the flexible pneumatic clamp mechanism, a section of soft material has multiple airbags built into it. The airbags are connected by an air tube, which serves as both an air inlet and an air outlet. Because the airbags are arranged closer to the outside of the elastic material, when the airbags expand, the deformation of the elastic material outside is greater than that on the inside, causing the airbags and the elastic material to bend. The flexible pneumatic clamp mechanism is connected to the No. 1 two-position three-way solenoid valve at the air pump outlet, and the No. 2 two-position two-way solenoid valve and the No. 3 two-position three-way solenoid valve are connected in series at the air pump inlet. The ends of the two branches are connected in parallel to the air tube to form a complete airbag inflation and deflation loop. By changing the working state of the air pump and the solenoid valve, the pressure state of the multiple airbags is controlled, realizing the bending and telescopic movement of the flexible pneumatic clamp mechanism.

[0014] In the pneumatic device structure, due to:

[0015] (1) The deformation of each airbag is the same, and the bending process is continuous. The total bending angle is the linear superposition of the bending deformation of each airbag;

[0016] (2) The entire mechanism consists of multiple airbags connected in series, and the large bending deformation of the mechanism is completed by the small-angle bending deformation of each series airbag;

[0017] (3) The stress-strain relationship is linear in the low strain region, and a linear fit is performed on the elastic material in the small deformation region;

[0018] The total bending angle of the complete pneumatic device is obtained by calculating the relationship between the air pressure of a single airbag and the bending angle and multiplying it by the number of airbags. The relationship between the air pressure of a single airbag and the bending angle is expressed as:

[0019]

[0020] Where l is the longitudinal length of the inner limiting layer of the airbag, which does not change during the entire bending process, b is the initial transverse length of the airbag, Δb is the airbag expansion length, P is the airbag pressure, m is the inner diameter of the trachea, c is the distance from the inner side of the elastic material to the airbag, e is the distance from the outer side of the elastic material to the airbag, E is the elastic modulus of the material, and θ is the bending angle of a single airbag.

[0021] The mechanism control strategy for combining rapid inflation and deflation with slow pulse inflation and deflation to precisely control the airbag pressure change in step 2 includes: for the slow pulse inflation process of the airbag, the dynamic control sequence of the air pump and the solenoid valve is as follows:

[0022] Valve No. 3 is in the normally closed state. First, valve No. 1 is in the open state, and then the state is delayed for time Δt. During the delay time, the working state and flow rate of the air pump are controlled by the pulse width modulation PWM signal. Then, valve No. 1 is closed and valve No. 2 is opened. This control sequence is repeated, and the air pressure in the airbag slowly increases. The speed of pressure increase is controlled by the delay time and the pump.

[0023] For the slow pulse deflation process of the airbag, the dynamic control sequence of the air pump and solenoid valve is:

[0024] Valve No. 1 is always in the closed state. First, valve No. 2 is in the closed state, and then the state is delayed for time Δt. During the delay time, the working state and flow rate of the pump are controlled by the PWM signal. After the delay time, the air pressure in the pipe section between the pump and valve No. 2 is lower than the air pressure in the airbag, and valves No. 2 and 3 become open. This cyclic control sequence is repeated, and the airbag pressure gradually decreases. The speed of pressure drop is controlled by the delay time and the pump.

[0025] Finally, the pressure between the clamping device and the insulator is selected to measure the degree of clamping of the insulator by the pneumatic device, and based on the selected observation quantity, the above-mentioned inflation and dispersion strategy is used to achieve smooth control of the insulator clamping process.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] Existing insulator cleaning mechanisms mostly use rigid robotic arms, which have poor adaptability to insulators of varying outer diameters. Furthermore, due to limitations in pneumatic design and the discrete opening / closing characteristics of valves, air pressure can drop dramatically, making precise and smooth pressure control difficult. This invention, based on a method for cleaning insulator surface contamination using a flexible pneumatic clamp mechanism, designs a control method for a flexible pneumatic clamp mechanism capable of completing the insulator clamping task. This method combines rapid inflation and deflation with slow pulse inflation and deflation to precisely control changes in the airbag pressure, achieving smooth control of the insulator clamping process. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the pneumatic clamp mechanism:

[0029] Among them, 1 is the inflation port, 2 is the device guide rail, 3 is the clamping device, 4 is the servo motor, 5 is the slider, 6 is the elastic material, and 7 is the airbag.

[0030] Figure 2Schematic diagram of the inflation and deflation circuit for the pneumatic mechanism:

[0031] Among them, 1 and 3 are two-position three-way solenoid valves, 2 is a two-position two-way solenoid valve, A is the air inlet, P is the air outlet, and O is connected to the atmosphere.

[0032] Figure 3 This is a schematic diagram of the longitudinal and cross sections of a single airbag expansion and bending, where Figure 3 (a) is a longitudinal cross-sectional view of the airbag. Figure 3 (b) is a transverse cross-sectional view of the airbag.

[0033] Figure 4 This is a schematic diagram of the slow pulse charging and discharging process, where Figure 4 (a) is a schematic diagram of the slow pulse inflation process. Figure 4 (b) is a schematic diagram of the slow pulse deflation process.

[0034] Figure 5 Schematic diagram of pressure closed-loop feedback.

[0035] Figure 6 Design a flow chart for the flexible clamp mechanism. DETAILED DESCRIPTION

[0036] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0037] like Figure 1 As shown, the clamp mechanism consists of two sections of elastic material and is fixed on a clamping device. The clamp is connected to the guide rail through a slider. The position of the slider can be manually adjusted to accommodate insulators with different outer diameters.

[0038] In step S1, Figure 2 As shown, multiple airbags are arranged within the elastic material. All airbags within the same section of elastic material are connected by a common air tube. The airbags are arranged closer to the outside of the elastic material. Therefore, when the airbags are inflated, the outside of the elastic material deforms more than the inside, causing the airbags and the elastic material to bend. The end of the air tube is connected to an inflation and deflation circuit consisting of a controller, air pump, and solenoid valves. The air pump outlet is connected to two-position, three-way solenoid valve No. 1, and the air pump inlet is connected in series with two-position, two-way solenoid valve No. 2 and two-position, three-way solenoid valve No. 3. The O-ports of both two-position, three-way solenoid valves are directly connected to the atmosphere. The ends of the two branches are connected in parallel to the air tube to form a complete airbag inflation and deflation circuit.

[0039] The two-position three-way solenoid valve is controlled by two coils. When one coil is energized for a moment and then the power is turned off, the valve becomes open. Figure 2The AP interface of valve 1 (or 3) is turned on; the other coil is energized for a moment and then the power is turned off, the valve becomes closed and the AO interface of the valve is turned on. When the two-position two-way solenoid valve is energized, the electromagnetic coil generates electromagnetic force to lift the closing member from the valve seat, and the valve becomes open. Figure 2 The middle figure shows that the AP interface of valve No. 2 is connected; when the power is off, the electromagnetic force disappears, the spring presses the closing part onto the valve seat, the valve closes, and the AP interface is not connected.

[0040] In the pneumatic device structure, due to:

[0041] (1) The deformation of each airbag is the same, and the bending process is continuous. The total bending angle can be linearly superimposed by the bending deformation of each airbag;

[0042] (2) The entire mechanism consists of multiple airbags connected in series, so that the large bending deformation of the mechanism is completed by the small-angle bending deformation of each series airbag;

[0043] (3) The stress-strain relationship is linear in the low strain region, and a linear fit can be performed on the elastic material in the small deformation region.

[0044] Based on the above analysis, the bending process of a single airbag after inflation and the longitudinal section of its effect on the elastic material are shown in the figure below. Figure 3 As shown in the figure, three major changes will occur in the clamp mechanism during the process of increasing air pressure. The bending angle of a single airbag is θ, the transverse length of the airbag increases by Δb, and the longitudinal length of the outer side of the elastic material increases by Δl. The increase in the transverse length of the airbag is due to the internal air pressure of the airbag acting on the elastic material. This process satisfies Hooke's law, as shown in formula (1):

[0045]

[0046] Where P is the internal pressure of the airbag, l is the longitudinal length of the inner limiting layer of the airbag, b is the transverse length of the airbag, E is the elastic modulus, and e is the distance from the airbag to the outside of the elastic material.

[0047] Figure 3 In the equation, F1 is the pressure generated by the airbag pressure on the upper surface, F2 is the elastic force generated by the elastic material on the upper surface, and F3 is the binding force generated by the limit layer to maintain the same length. When the air pressure in the airbag is stable and the mechanism is in a stable state and no longer bends, the three forces and the torques they generate reach equilibrium:

[0048]

[0049] F1 can be calculated by multiplying the pressure by the area, and F2 can be calculated by Hooke's law:

[0050]

[0051] Where m is the distance from the air pipe to the inner wall of the airbag. When calculating the torque, F1 and F2 act on all points on the upper surface of the airbag. The deformation of each point and the torque on the rotating shaft are not consistent, so the integral method is used to calculate it. Taking the method of calculating the torque M1 of F1 as an example, the upper surface of the airbag is semicircular. After performing differential element processing on it, the unit area dA1 can be expressed as:

[0052] dA1=rdrdφ (4)

[0053] Where r is the integral radius and φ is the integral angle. The pressure and force arm L1 exerted by the airbag on this small element are shown in formula (5):

[0054]

[0055] Where c is the distance from the inner wall of the airbag to the inner side of the elastic material. The integral range can be determined based on the airbag range shown in the cross-sectional diagram. Substituting equation (5) into the torque formula, M1 can be obtained:

[0056]

[0057] Similarly, M2 and M3 can be calculated:

[0058]

[0059] Substituting equations (6) and (7) into (2) yields the air pressure and bending angle of a single airbag:

[0060]

[0061] At this point, the mathematical modeling of the airbag pressure and bending angle described in step S1 is performed, and equation (8) is multiplied by the number of airbags n to obtain:

[0062]

[0063] In step S2, based on the flexible pneumatic clamp mechanism model, five working states of the air pump and solenoid valve are designed to respectively realize rapid inflation, rapid deflation, holding, slow pulse inflation, and slow pulse deflation of the airbag, thereby completing the precise control of the airbag pressure and the mechanism clamp movement.

[0064] (1) Rapid inflation: valve 1 and valve 2 are in the open state, valve 3 is in the closed state. When the pump is working, the air flow channel can be Figure 2 In the figure, it is represented as entering from the O gas port of valve 3, passing through valve 2, air pump, valve 1, and being pumped into the air bag.

[0065] (2) Rapid deflation: valve 2 and valve 3 are in the open state, valve 1 is in the closed state. When the pump works and absorbs air from the airbag, the air flow channel can be Figure 2In the figure, the air in the airbag passes through valve 3, valve 2, and the air pump, and is discharged from the O port of valve 1. After this process, the pressure in the airbag can drop to a negative state, and the deflation speed can be controlled by adjusting the operating speed of the pump.

[0066] (3) Hold: All valves are closed.

[0067] (4) Slow pulse inflation: Figure 4 As shown in Figure (a), a dynamic control sequence for the air pump and solenoid valve is designed, with valve 3 in the normally closed state. First, valve 1 is opened, and then this state is delayed for a period of time, Δt. During this delay, a pulse-width modulation (PWM) signal can be used to control the air pump's operating state (on or off) and flow rate, pumping a small amount of air from the pipe section between valves 1 and 2 into the airbag. Then, valve 1 is closed, and valve 2 is opened, replenishing the air in the pipe section between valves 1 and 2. Repeating this sequence will slowly increase the air pressure within the airbag, and the rate of pressure increase can be controlled by the delay time and the pump.

[0068] (5) Slow pulse inflation: Figure 4 As shown in (b), a dynamic control sequence for the air pump and solenoid valve is designed, with valve No. 1 always in the closed state. First, valve No. 2 is in the closed state, and then this state is delayed for a period of time Δt. During the delay time, the operating state (open or closed) and flow rate of the pump can be controlled by a PWM signal, and the air in the pipe section between valves No. 1 and No. 2 is discharged to the atmosphere through valve No. 1. After the delay time, the air pressure in the pipe section between the pump and valve No. 2 is lower than the air pressure in the airbag, and valves No. 2 and No. 3 become open. After a cycle of slow pulsed deflation, a small pressure drop is achieved in the airbag. By repeating this cyclic control sequence, the airbag pressure gradually decreases. The rate of pressure drop can be controlled by the delay time and the pump.

[0069] A suitable observable quantity is selected to measure the degree of gripping of the insulator by the pneumatic device. Here, the pressure between the clamp device and the insulator, which can be monitored by a pressure sensor, is selected as the indicator.

[0070] So far, step S2 has been described, based on the above-mentioned inflation and dispersion strategy, to design a closed-loop feedback control, the control principle is as follows: Figure 5 First, set the desired pressure and acceptable error range between the clamp device and the insulator. In each calculation cycle, the controller receives the actual pressure measured by the sensor and converts the desired pressure (P target ) and actual pressure (P t ) and calculate the error e(t)=P target -P tIf the error exceeds the acceptable tolerance, the pump and valve are controlled using an inflation / deflation strategy based on the error. The error determines whether inflation or deflation is needed. If the error is greater than zero, the airbag is over-deflated if the error e(t-1) from the previous calculation cycle is less than zero. In the case of over-deflation, the airbag is inflated slowly in a pulsed manner. Otherwise, the air pump and solenoid valve are controlled based on the error to directly inflate. The deflation process is similar. Finally, the pressure is measured and dynamically adjusted to reach the target pressure within the allowable error.

[0071] In addition to the above embodiments, the present invention may also have other implementation methods. Any technical solutions formed by equivalent replacement or equivalent transformation fall within the protection scope required by the present invention.

Claims

1. A method for cleaning dirt on the surface of an insulator based on a flexible pneumatic clamp mechanism, characterized in that: The following steps are involved: Step S1: Based on the flexible pneumatic clamp mechanism that completes the insulator clamping task, the working process and principle of the airbag structure are analyzed, and the airbag pressure and bending angle are mathematically modeled; Step S2: Based on the flexible pneumatic clamp mechanism model, in view of the requirement for the bending movement of the mechanism during the process of clamping the insulator, a mechanism control strategy combining rapid inflation and deflation with slow pulse inflation and deflation is proposed to accurately control the change of airbag pressure, thereby achieving smooth control of the insulator clamping process.

2. The method for cleaning dirt on the surface of an insulator based on a flexible pneumatic clamp mechanism according to claim 1, characterized in that: The step S1 mathematically models the airbag pressure and the bending angle as follows: In the flexible pneumatic clamp mechanism, a section of soft material has multiple airbags built into it. The airbags are connected by an air tube, which serves as both an air inlet and an air outlet. Because the airbags are arranged closer to the outside of the elastic material, when the airbags expand, the deformation of the elastic material outside is greater than that on the inside, causing the airbags and the elastic material to bend. The flexible pneumatic clamp mechanism is connected to the No. 1 two-position three-way solenoid valve at the air pump outlet, and the No. 2 two-position two-way solenoid valve and the No. 3 two-position three-way solenoid valve are connected in series at the air pump inlet. The ends of the two branches are connected in parallel to the air tube to form a complete airbag inflation and deflation loop. By changing the working state of the air pump and the solenoid valve, the pressure state of the multiple airbags is controlled, realizing the bending and telescopic movement of the flexible pneumatic clamp mechanism. In the pneumatic device structure, due to: (1) The deformation of each airbag is the same, and the bending process is continuous. The total bending angle is the linear superposition of the bending deformation of each airbag; (2) The entire mechanism consists of multiple airbags connected in series, and the large bending deformation of the mechanism is completed by the small-angle bending deformation of each series airbag; (3) The stress-strain relationship is linear in the low strain region, and a linear fit is performed on the elastic material in the small deformation region; The total bending angle of the complete pneumatic device is obtained by calculating the relationship between the air pressure of a single airbag and the bending angle and multiplying it by the number of airbags. The relationship between the air pressure of a single airbag and the bending angle is expressed as: Where l is the longitudinal length of the inner limiting layer of the airbag, which does not change during the entire bending process, b is the initial transverse length of the airbag, Δb is the airbag expansion length, P is the airbag pressure, m is the inner diameter of the trachea, c is the distance from the inner side of the elastic material to the airbag, e is the distance from the outer side of the elastic material to the airbag, E is the elastic modulus of the material, and θ is the bending angle of a single airbag.

3. According to the method for cleaning contamination on the surface of an insulator based on a flexible pneumatic clamp mechanism in claim 1, the mechanism control strategy of combining rapid inflation and deflation with slow pulse inflation and deflation to precisely control the airbag pressure change in step 2 is characterized by: For the slow pulse inflation process of the airbag, the dynamic control sequence of the air pump and solenoid valve is: Valve No. 3 is in the normally closed state. First, valve No. 1 is in the open state, and then the state is delayed for time Δt. During the delay time, the working state and flow rate of the air pump are controlled by the pulse width modulation PWM signal. Then, valve No. 1 is closed and valve No. 2 is opened. This control sequence is repeated, and the air pressure in the airbag slowly increases. The speed of pressure increase is controlled by the delay time and the pump. For the slow pulse deflation process of the airbag, the dynamic control sequence of the air pump and solenoid valve is: Valve No. 1 is always in the closed state. First, valve No. 2 is in the closed state, and then the state is delayed for time Δt. During the delay time, the working state and flow rate of the pump are controlled by the PWM signal. After the delay time, the air pressure in the pipe section between the pump and valve No. 2 is lower than the air pressure in the airbag, and valves No. 2 and 3 become open. This cyclic control sequence is repeated, and the airbag pressure gradually decreases. The speed of pressure drop is controlled by the delay time and the pump.

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