Semi-sliding formwork control method

Abstract

The present invention discloses a semi-sliding mode frame pulling control method, which controls whether to apply the hydraulic support frame pulling force according to the u value in formula (1). When , the frame pulling force F is applied; when , the frame pulling force F is canceled. The present invention has the advantages of constructing a spatial model according to the hydraulic support group frame pulling control process, providing a semi-sliding mode frame pulling control method, improving the frame pulling control accuracy of the hydraulic support group, thereby ensuring the straightness of the hydraulic support group, fundamentally avoiding the coal wall slab, hydraulic support crushing, roof collapse and other accidents caused by insufficient straightness of the hydraulic support group, as well as the problem of too low coal output efficiency, ensuring the production safety of the coal mine working face and the coal mine generation benefits.

Description

Technical Field

[0001] The invention relates to the field of coal mining, in particular to a semi-slip formwork frame control method. Background Art

[0002] The underground working face of the coal mine is composed of hundreds of hydraulic supports arranged horizontally. As the coal mining working face moves forward, the hydraulic support group also needs to complete the actions of pushing and pulling. After the hydraulic support group completes the pushing, the telescopic rod between the hydraulic support and the scraper conveyor is in a stretched state, and then the pulling operation is performed, that is, the scraper conveyor is fixed, the telescopic rod is retracted, and the hydraulic support is brought closer to the scraper conveyor. In this process, the pulling control method of the hydraulic support group is the key to determining the straightness of the hydraulic support group. If the straightness of the hydraulic support group is not enough, it may cause uneven force on the hydraulic support group, resulting in the phenomenon of the hydraulic support looking up or down, especially under geological conditions such as soft coal seams and broken coal seams, which is very likely to cause coal wall spalling, hydraulic support crushing, roof collapse and other accidents. At the same time, if the straightness of the hydraulic support group is not enough, the scraper conveyor will be severely bent, resulting in uneven cutting depth of the coal mining machine when mining the coal wall, resulting in too low coal output efficiency, which seriously affects the generation efficiency of the coal mine. Therefore, precise control of the hydraulic support group's pulling action is an important link in ensuring safe production of coal mine working faces and guaranteeing coal mine generation benefits.

[0003] However, due to the short pulling distance of the hydraulic support group and the small actual space, it is impossible to install data acquisition equipment such as pressure sensors. Therefore, during the pulling process of the hydraulic support group, it is impossible to obtain necessary data such as the pulling force of the hydraulic support group, the friction between the support base and the bottom plate, and the friction between the top beam and the top plate. As a result, even today when computer control calculations are highly developed, manual operation is still required to realize the pulling action of the hydraulic support group.

[0004] At present, the more advanced hydraulic support group pulling control methods include the set experience value method, the online two-point extrapolation or three-point extrapolation method, and the Kalman filter method. However, since the state of the bottom plate is different for each advance of the coal mining face, the direct use of the set experience value method is often ineffective. In addition, the online two-point extrapolation or three-point extrapolation method divides the hydraulic support group pulling process into two or three sections. The front part of the pulling process is used to estimate the tension F and the comprehensive resistance f, and the latter part is based on the estimated tension F and the comprehensive resistance f. The model is established to pull the hydraulic support group into place. However, since the spatial distance of the pulling frame is very short and the speed is very fast, it is difficult to meet the requirements of segmented pulling, so this method is usually difficult to implement in practice. The Kalman filter method estimates the pulling force of the pulling frame in real time online and dynamically adjusts the pulling pressure. However, since the single-speed valve or dual-speed valve currently used in hydraulic supports is mostly used, the pressure is adjusted according to the opening ratio; at the same time, the hydraulic system cannot withstand the impact of pressure pulses, so it is impossible to use pulse-type fluid supply to adjust the pressure. Therefore, the Kalman filter method cannot be implemented in practice. Summary of the invention

[0005] The present invention aims to construct a spatial model according to the hydraulic support group tensioning control process, provide a semi-sliding mode tensioning control method, improve the tensioning control accuracy of the hydraulic support group, and thus ensure the straightness of the hydraulic support group.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The semi-sliding formwork frame control method of the present invention comprises the following contents:

[0008] Whether to apply the hydraulic support pulling force is controlled according to the u value in formula (1);

[0009] (1)

[0010] Where C is a constant, is the difference between the expected arrival position of the hydraulic support and the current position of the hydraulic support; for The first-order derivative of; F is the tension force of the hydraulic support frame.

[0011] Furthermore, in formula (1) When , the tension F is applied; when When , cancel the rack pulling force F.

[0012] Furthermore, in formula (1) is equal to 0 and When it is equal to 0, the semi-slipform pulling control of the hydraulic support ends and the hydraulic support reaches the desired position.

[0013] The advantage of the present invention is that a spatial model is constructed according to the hydraulic support group pulling control process, a semi-sliding mode pulling control method is provided, the pulling control accuracy of the hydraulic support group is improved, thereby ensuring the straightness of the hydraulic support group, and fundamentally avoiding accidents such as coal wall spalling, hydraulic support crushing, roof collapse, and the problem of low coal output efficiency caused by insufficient straightness of the hydraulic support group, thereby ensuring the production safety of the coal mine working face and the benefits generated by the coal mine. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a diagram of the control space structure of the hydraulic support rack according to the present invention.

[0015] Figure 2 It is a schematic diagram of the hydraulic support pulling process of the present invention.

[0016] Figure 3 It is a schematic diagram of the sliding form control process of the hydraulic support pulling frame described in the present invention.

[0017] Figure 4It is a state variable change process diagram of the present invention.

[0018] Figure 5 It is a simulation control effect diagram of the semi-sliding mode pulling frame control method described in the present invention. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention are described clearly and completely below. 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.

[0020] like Figure 1 As shown, Figure 1 -a is a side view, 1-b is a top view. After the hydraulic support 1 completes the push and slide operation, the telescopic rod 2 is in a stretched state; then the support is pulled, that is, the scraper conveyor 3 is fixed, the telescopic rod 2 is retracted, and the hydraulic support 1 is moved closer to the scraper conveyor 3. When the support is pulled, the base of the hydraulic support 1 is not completely close to the scraper conveyor 3, but stops at a certain stop point 4.

[0021] like Figure 2 The figure shows the schematic diagram of the hydraulic support 1 pulling process, where m is the mass of the hydraulic support, F is the pulling force, f is the comprehensive resistance of the hydraulic support, and S is the running displacement of the hydraulic support. Due to the short pulling distance and the small actual space, it is impossible to install data acquisition equipment such as pressure sensors, so it is impossible to obtain the pulling force F and the comprehensive resistance f of the hydraulic support during the pulling process of the hydraulic support 1. Therefore, the pulling process of the hydraulic support 1 is highly compatible with the sliding mode control.

[0022] Sliding mode control (SMC), also known as variable structure control, is essentially a special type of nonlinear control, and the nonlinearity is manifested as control discontinuity. The difference between this control strategy and other controls is that the "structure" of the system is not fixed, but can be purposefully changed continuously in the dynamic process according to the current state of the system (such as deviation and its derivatives of various orders, etc.), forcing the system to move according to the state trajectory of the predetermined "sliding mode". Since the sliding mode can be designed and is independent of the object parameters and disturbances, this makes the sliding mode control have the advantages of fast response, insensitivity to parameter changes and disturbances, no need for online system identification, and simple physical implementation.

[0023] However, the hydraulic support 1 pulling process also has two outstanding characteristics:

[0024] First, the pulling force F can only be applied in one direction during the hydraulic support 1 pulling process, that is, the pulling force F can only be applied in the direction in which the hydraulic support 1 moves to the predetermined position.

[0025] Second, the pulling force F can only be executed in two modes: applying and canceling.

[0026] However, a general sliding mode control process requires that the direction of the control quantity can be switched. Therefore, the present application proposes a semi-sliding mode rack control method.

[0027] Whether to apply the hydraulic support pulling force is controlled according to the u value in formula (1);

[0028] (1)

[0029] Where C is a constant, is the difference between the expected arrival position of the hydraulic support and the current position of the hydraulic support; for The first-order derivative of; F is the tension force of the hydraulic support frame.

[0030] When in formula (1) When , the tension F is applied; when When , cancel the rack pulling force F.

[0031] When in formula (1) =0 and =0, the semi-slipform pulling control of the hydraulic support ends and the hydraulic support reaches the desired position.

[0032] The basis of the semi-sliding mode rack control method is as follows:

[0033] Assume that the expected arrival position of the hydraulic support is , the current position of the hydraulic support is S, then let

[0034] (2)

[0035] At the same time, order:

[0036] (3)

[0037] In the formula, is the movement speed of the bracket.

[0038] According to the principles of kinematics:

[0039] (4)

[0040] Therefore, when the bracket applies tension, the system satisfies the following state equation

[0041] (5)

[0042] When the bracket closes the valve and there is no tension, the system satisfies the following state equation

[0043] (6)

[0044] Combining (4) and (5), we can obtain the following state equation:

[0045] (7)

[0046] In the formula,

[0047] (8)

[0048] in, About and function.

[0049] That is, you can change the variable and is regarded as the state variable of sliding mode control. Run from the initial moment and enter the sliding surface, such as Figure 3 As shown, the system converges as the sliding surface slides toward the origin. For the hydraulic support 1 pulling process, it can be determined that is the sliding surface, let

[0050] (9)

[0051] Then when the system state variable When reaching the sliding surface,

[0052] (10)

[0053] Right now

[0054] (11)

[0055] Available

[0056] (12)

[0057] in, The hydraulic support reaches the initial position of the sliding surface.

[0058] This shows that, over a period of time, It will converge to the origin of the coordinates, that is, the displacement of the bracket reaches a given value. Since the bracket puller only has positive tension, the semi-sliding mode puller control method of the present invention can be designed according to formula (6).

[0059] According to the semi-sliding mode drawer control method of the present invention, a simulation model is established in Simulink of Matlab. The simulation results are as follows: Figure 4As shown, the state variable The dynamic change process and Figure 3 The sliding process of the bracket pulling is highly matched, indicating that the control model and control strategy can move the bracket to the specified position. Figure 5 As shown, after about 5 seconds, the bracket can be moved to the specified position.

Claims

1. A semi-sliding formwork rack control method, characterized in that: Whether to apply the hydraulic support pulling force is controlled according to the u value in formula (1); （1） Where C is a constant, is the difference between the expected arrival position of the hydraulic support and the current position of the hydraulic support; for The first-order derivative of; F is the tension force of the hydraulic support; and .

2. The semi-sliding formwork control method according to claim 1, characterized in that: In formula (1) When , the tension F is applied; when When , cancel the rack pulling force F.

3. The semi-sliding formwork control method according to claim 1, characterized in that: In formula (1) and When , the semi-slipform pulling control of the hydraulic support ends and the hydraulic support reaches the desired position.

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