Hydraulic excitation bias adjustment device, method and hydraulic excitation system

Abstract

The present invention relates to a hydraulic excitation system and provides a hydraulic excitation bias adjustment device, including a servo valve, which is arranged between a double-acting hydraulic cylinder and an alternating flow distribution pump to adjust the flow rate of the alternating fluid flow input from the alternating flow distribution pump to the double-acting hydraulic cylinder; a displacement sensor, which is used to detect the actual displacement signal of the double-acting hydraulic cylinder; a controller, which is electrically connected to the displacement sensor and the servo valve respectively, and is used to perform the following operations: obtaining the actual displacement signal and deriving the deviation between the target displacement signal and the actual displacement signal; outputting a deviation control signal according to the deviation control to adjust the valve opening of the servo valve and perform bias compensation on the displacement and speed of the double-acting hydraulic cylinder. The hydraulic excitation bias adjustment device of the present invention can perform bias adjustment on the displacement of the hydraulic cylinder during the excitation process to ensure that the displacement of the hydraulic cylinder meets the set requirements. The present invention also provides a hydraulic excitation bias adjustment method and a hydraulic excitation system.

Description

Technical Field

[0001] The present invention relates to a hydraulic excitation system, and in particular to a hydraulic excitation bias adjustment device, a hydraulic excitation bias adjustment method, and a hydraulic excitation system. Background Art

[0002] Hydraulic vibration systems are widely used in many fields. Due to their advantages such as high power density, large displacement and thrust, and multiple controllable parameters, they are widely used in industries such as vehicles, construction, ocean, aerospace, and nuclear industry.

[0003] Currently, widely used electro-hydraulic vibration equipment includes rotary valve-controlled vibration equipment. For example, Chinese invention patent CN104763604B discloses an alternating flow distribution pump for controlling a hydraulic excitation system. This pump utilizes a rotating valve plate to continuously rotate and directly output an alternating fluid flow. However, due to nonlinear factors such as leakage and friction in the alternating flow distribution pump and the pump-controlled hydraulic cylinder, the bidirectional fluid flow is not completely symmetrical, the bidirectional speed of the pump-controlled hydraulic cylinder is not completely matched, and the median displacement of the hydraulic cylinder shifts during the excitation process. Because the alternating flow distribution pump directly generates the alternating fluid flow through the rotation of the valve plate, if it has inherent asymmetry, it is impossible to adjust the hydraulic cylinder offset by controlling the internal components. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a hydraulic excitation bias adjustment device, which can adjust the bias of the hydraulic cylinder during the excitation process, so that the bidirectional fluid flow of the hydraulic cylinder is symmetrical, ensuring that the bidirectional speeds of the hydraulic cylinder match each other, and achieving the set requirement that the median value of the hydraulic cylinder displacement remains unchanged.

[0005] Furthermore, the technical problem to be solved by the present invention is to provide a hydraulic excitation system, in which the median value of the displacement of the hydraulic cylinder does not deviate during the excitation process, thus meeting the set requirements.

[0006] The technical problem that the present invention also aims to solve is to provide a hydraulic excitation bias adjustment method, which can adjust the bias of the hydraulic cylinder during the excitation process, so that the bidirectional fluid flow of the hydraulic cylinder is symmetrical, ensuring that the bidirectional speeds of the hydraulic cylinder match each other, and meeting the set requirements of the hydraulic cylinder displacement.

[0007] In order to solve the above technical problems, the present invention provides a hydraulic excitation bias adjustment device, which includes: a servo valve, which is arranged between the double-acting hydraulic cylinder and the alternating distribution pump to be able to adjust the flow rate of the alternating fluid flow input by the alternating distribution pump into the double-acting hydraulic cylinder; a displacement sensor, which is used to detect the actual displacement signal of the double-acting hydraulic cylinder; a controller, which is electrically connected to the displacement sensor and the servo valve respectively, and is used to perform the following operations: obtain the actual displacement signal and obtain the deviation between the target displacement signal and the actual displacement signal; output a deviation control signal according to the deviation control to adjust the valve port opening of the servo valve and perform offset compensation on the displacement and speed of the double-acting hydraulic cylinder.

[0008] Specifically, outputting a deviation control signal according to the deviation control includes: obtaining a target speed according to the target displacement signal; if the target speed is greater than or equal to 0, using the deviation as the deviation control signal; if the target speed is less than 0, inverting the deviation as the deviation control signal; adjusting the control current of the servo valve according to the deviation control signal to adjust the valve opening of the servo valve and perform bias compensation on the displacement and speed of the double-acting hydraulic cylinder.

[0009] Specifically, the controller includes a PID controller, and the PID controller adjusts the control current of the servo valve according to the deviation control signal.

[0010] Preferably, the PID controller is a segmented PID controller, and the segmented PID controller performs the following operations: when the absolute value of the target speed is greater than or equal to a set value, the proportional parameter of the segmented PID controller is set to a first proportional coefficient; when the absolute value of the target speed is less than the set value, the proportional parameter of the segmented PID controller is set to a second proportional coefficient; wherein, the first proportional coefficient is less than the second proportional coefficient.

[0011] Preferably, the controller is further configured to perform the following operations: obtaining a target sinusoidal curve of the displacement of the double-acting hydraulic cylinder, sampling the actual displacement signal of the double-acting hydraulic cylinder multiple times in each cycle to form an actual displacement curve, and calculating a phase difference between the target sinusoidal curve of the displacement of the double-acting hydraulic cylinder and the actual displacement curve based on the multiple sampling results, so as to control the servo valve to perform phase correction in the next cycle, wherein the formula for calculating the phase difference ψ is as follows:

[0012]

[0013] Among them, n is the number of sampling points in one cycle, i is the sampling sequence number, and x iis the actual displacement signal of the double-acting hydraulic cylinder sampled for the i-th time.

[0014] Furthermore, the present invention provides a hydraulic excitation system, comprising the hydraulic excitation bias adjustment device described in any one of the above technical solutions.

[0015] Correspondingly, the present invention also provides a hydraulic excitation bias adjustment method, which is used to set a servo valve between an alternating distribution pump that outputs an alternating fluid flow and a double-acting hydraulic cylinder. The method includes the following steps: obtaining the actual displacement signal of the double-acting hydraulic cylinder, and obtaining the deviation between the target displacement signal and the actual displacement signal; outputting a deviation control signal according to the deviation control to adjust the valve opening of the servo valve and perform bias compensation on the displacement and speed of the double-acting hydraulic cylinder.

[0016] Specifically, obtaining the deviation between the target displacement signal and the actual displacement signal includes the following steps: obtaining a target speed based on the target displacement signal; judging the target speed, and if the target speed is greater than or equal to 0, using the deviation as a deviation control signal; if the target speed is less than 0, inverting the deviation as the deviation control signal; and adjusting the control current of the servo valve based on the deviation control signal to adjust the valve opening of the servo valve and perform offset compensation on the displacement and speed of the double-acting hydraulic cylinder.

[0017] Preferably, the control current of the servo valve is adjusted according to the deviation control signal through PID control, wherein the PID control adopts segmented PID control, including the following steps: when the absolute value of the target speed is greater than or equal to the set value, the proportional parameter of the segmented PID control is set to a first proportional coefficient; when the absolute value of the target speed is less than the set value, the proportional parameter of the segmented PID control is set to a second proportional coefficient; wherein the first proportional coefficient is less than the second proportional coefficient.

[0018] Preferably, the method further comprises the following steps: obtaining a target sinusoidal curve of the displacement of the double-acting hydraulic cylinder, sampling the actual displacement signal of the double-acting hydraulic cylinder multiple times within one cycle to form an actual displacement curve, and calculating a phase difference between the target sinusoidal curve of the displacement of the double-acting hydraulic cylinder and the actual displacement curve based on the multiple sampling results, so as to control the servo valve to perform phase correction within the next cycle, wherein the formula for calculating the phase difference ψ is as follows:

[0019]

[0020] Among them, n is the number of sampling points in one cycle, i is the sampling sequence number, and x i is the actual displacement signal of the double-acting hydraulic cylinder sampled for the i-th time.

[0021] Through the above scheme, the beneficial effects of the present invention are as follows:

[0022] The hydraulic excitation bias adjustment device of the present invention is provided with a servo valve between the double-acting hydraulic cylinder and the alternating flow distribution pump. In the process of the alternating flow distribution pump continuously inputting alternating fluid flow to the double-acting hydraulic cylinder through the servo valve, the displacement sensor will detect the actual displacement signal of the double-acting hydraulic cylinder in real time, and compare the actual displacement signal with the target displacement signal through the controller to obtain the deviation between the target displacement signal and the actual displacement signal. Since the valve port opening of the servo valve is related to the magnitude of its control current, a deviation control signal can be output according to the obtained deviation, thereby controlling the control current of the servo valve according to the output deviation control signal, and then adjusting the valve port opening of the servo valve, so that the bidirectional flow input by the alternating flow distribution pump into the double-acting hydraulic cylinder through the servo valve is synchronously reduced, thereby realizing offset compensation of the displacement and speed of the double-acting hydraulic cylinder, and ensuring that the displacement of the double-acting hydraulic cylinder meets the set target and does not offset.

[0023] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0025] Figure 1 1 is a connection diagram of a specific embodiment of the hydraulic excitation bias adjustment device of the present invention;

[0026] Figure 2 This is a schematic diagram of the working principle of the alternating flow distribution pump;

[0027] Figure 3 It is the time-displacement motion characteristic diagram of the hydraulic cylinder controlled by the alternating flow pump;

[0028] Figure 4 It is the displacement-velocity motion characteristic of the hydraulic cylinder controlled by the alternating flow pump;

[0029] Figure 5 It is a segmented schematic diagram of a specific embodiment of the segmented PID control of the hydraulic excitation bias adjustment device of the present invention;

[0030] Figure 6 This is a principle block diagram of a first specific embodiment of the hydraulic excitation bias adjustment device of the present invention;

[0031] Figure 7 This is a principle block diagram of a second specific embodiment of the hydraulic excitation bias adjustment device of the present invention;

[0032] Figure 8 The displacement curves of the hydraulic cylinder when it is directly controlled by the alternating flow distribution pump and when it is controlled by the hydraulic excitation bias adjustment device of the present invention are shown;

[0033] Figure 9 This is a graph showing the median displacement change of the hydraulic cylinder when it is directly controlled by the alternating flow distribution pump and when it is controlled by the hydraulic excitation bias adjustment device of the present invention;

[0034] Figure 10 This is a curve diagram showing the percentage of valve core displacement of the servo valve of the hydraulic excitation bias adjustment device of the present invention in the total range.

[0035] Description of Reference Numerals

[0036] 1 alternating flow pump 2 servo valve

[0037] 3 double-acting hydraulic cylinders 4 displacement sensors

[0038] 5 controllers DETAILED DESCRIPTION

[0039] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and the scope of protection of the present invention is not limited to the specific embodiments described below.

[0040] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "formed," "provided with," "arranged," "connected," etc. should be understood in a broad sense. For example, the connection may be a direct connection or an indirect connection through an intermediate medium; it may be a fixed connection, a detachable connection, or an integral connection; it may be a direct connection or an indirect connection through an intermediate connector; it may be internal communication between two elements or an interaction between two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] The present invention provides a hydraulic excitation bias adjustment device, see Figure 1As a specific embodiment of the hydraulic excitation bias adjustment device of the present invention, it includes a servo valve 2, a displacement sensor 4 and a controller 5, wherein the servo valve 2 is arranged between the double-acting hydraulic cylinder 3 and the alternating flow distribution pump 1 to be able to adjust the flow rate of the alternating fluid flow input from the alternating flow distribution pump 1 to the double-acting hydraulic cylinder 3. Specifically, the P oil port and the T oil port of the servo valve 2 are connected to the two oil outlets of the alternating flow distribution pump 1, and the A oil port and the B oil port of the servo valve 2 are respectively connected to the two working chamber interfaces of the double-acting hydraulic cylinder 3. In the working state, the valve port of the servo valve 2 is opened, so that the P oil port is connected to the A oil port and the B oil port. One oil port, the T oil port is connected to the other oil port of the two oil ports, and the alternating flow distribution pump 1 continuously inputs alternating fluid to the P oil port and the T oil port, thereby controlling the double-acting hydraulic cylinder 3 to excite, and the displacement sensor 4 is configured to detect the actual displacement signal of the double-acting hydraulic cylinder 3. The controller 5 is electrically connected to the displacement sensor 4 and the servo valve 2 respectively, and the controller 5 is used to perform the following operations: obtain the actual displacement signal, and obtain the deviation between the target displacement signal and the actual displacement signal; control the output deviation control signal according to the deviation to adjust the valve port opening of the servo valve 2, and perform offset compensation on the displacement and speed of the double-acting hydraulic cylinder 3.

[0042] It should be noted that the alternating flow pump 1 is a hydraulic control pump that can output alternating fluid flow by itself, and can control the frequency and output flow of the alternating fluid flow by itself, thereby controlling the reciprocating frequency and excitation amplitude of the double-acting hydraulic cylinder 3. The structural form of the alternating flow pump 1 is diverse. Among them, as a specific structural form of the alternating flow pump 1, it mainly includes a fixed flow distribution plate, a rotating flow distribution plate, a plunger cylinder body and a swash plate. The rear end face of the rotating flow distribution plate contacts the front end face of the fixed flow distribution plate, and the front end face of the rotating flow distribution plate contacts the plunger cylinder body. The plunger cylinder body has multiple circular holes distributed along the circumference, and a plunger is inserted in each circular hole. The multiple plungers can move along the axial direction of the plunger cylinder body, and a swash plate is set at the front end of the multiple plungers. The rotation axis of the swash plate forms an angle with the axis of the plunger cylinder body. When working, each plunger is pressed against the working surface of the swash plate under the action of the hydraulic oil in the plunger cylinder body. As a result, the lengths of each plunger extending out of the end face of the plunger cylinder body are different; the working section of the fixed distribution plate forms two inner and outer annular grooves of different diameters, the two annular grooves extend axially inward, the inner annular groove is connected to one working chamber interface of the double-acting hydraulic cylinder 3, and the outer annular groove is connected to the other working chamber interface of the double-acting hydraulic cylinder 3; the rotating distribution plate is provided with two inner distribution channels I and outer distribution channels II with arc-shaped cross-sections; when the alternating distribution pump 1 is working, by continuously rotating the plunger cylinder body, under the action of the swash plate, the plunger is made to reciprocate in the plunger cylinder body, forming a phase-fixed oil suction area and oil discharge area, and by driving the rotating distribution plate to rotate, the rotating distribution plate is rotated relative to the fixed distribution plate, and the rotating distribution plate is rotated relative to the plunger cylinder body, so that the contact area between the two distribution channels I and II of the rotating distribution plate and the oil suction area and oil discharge area of ​​the plunger cylinder body changes, such as Figure 2 As shown, the zero point of the rotation angle of the two distribution channels I and II of the rotating distribution plate is defined as φ = 0°. The contact area between the inner distribution channel I of the rotating distribution plate and the oil suction and discharge areas of the plunger cylinder is the same, and the contact area between the outer distribution channel II of the rotating distribution plate and the oil suction and discharge areas of the plunger cylinder is the same. That is, the input flow rate of the inner annular groove D of the fixed distribution plate and the output flow rate of the outer annular groove C are zero. As the rotating distribution plate rotates, the input and output flow rates of the alternating distribution pump change as follows:

[0043] 0°<φ<90°: The contact area between the inner distribution channel I of the rotating distribution plate and the oil suction area of ​​the plunger cylinder, as well as the contact area between the outer distribution channel II of the rotating distribution plate and the oil discharge area of ​​the plunger cylinder, gradually increases. Then, the input flow rate of the inner annular groove D of the fixed distribution plate and the output flow rate of the outer annular groove C both increase.

[0044] φ=90°: The input flow of the inner annular groove D of the fixed distribution plate and the output flow of the outer annular groove C reach the maximum;

[0045] 90°<φ<180°: The contact area between the inner distribution channel I of the rotating distribution plate and the oil suction area of ​​the plunger cylinder, as well as the contact area between the outer distribution channel II of the rotating distribution plate and the oil discharge area of ​​the plunger cylinder, gradually decreases. Therefore, the input flow rate of the inner annular groove D of the fixed distribution plate and the output flow rate of the outer annular groove C both decrease.

[0046] φ=180°: the input flow of the inner annular groove D of the fixed distribution plate and the output flow of the outer annular groove C are reduced to zero;

[0047] 180°<φ<270°: The contact area between the outer distribution channel II of the rotating distribution plate and the oil suction area of ​​the plunger cylinder, as well as the contact area between the inner distribution channel I of the rotating distribution plate and the oil discharge area of ​​the plunger cylinder, gradually increases. The input flow of the outer annular groove C of the fixed distribution plate and the output flow of the inner annular groove D both increase.

[0048] φ=270°: The input flow of the outer annular groove C of the fixed distribution plate and the output flow of the inner annular groove D reach the maximum;

[0049] 270°<φ<360°: The contact area between the outer distribution channel II of the rotating distribution plate and the oil suction area of ​​the plunger cylinder, as well as the contact area between the inner distribution channel I of the rotating distribution plate and the oil discharge area of ​​the plunger cylinder, gradually decreases. As a result, the input flow rate of the outer annular groove C of the fixed distribution plate and the output flow rate of the inner annular groove D both decrease.

[0050] φ=360°: the input flow of the outer annular groove C of the fixed distribution plate 5 and the output flow of the inner annular groove D are reduced to zero;

[0051] In this cycle, the two oil ports of the alternating flow distribution pump 1 will form oil with alternating flow and direction, thereby driving the double-acting hydraulic cylinder 3 to reciprocate. By changing the rotation speed of the rotating distribution plate, the reciprocating frequency of the double-acting hydraulic cylinder 3 changes accordingly; by changing the cylinder speed (plunger cylinder speed), the output flow of the plunger pump changes, so that the excitation amplitude of the double-acting hydraulic cylinder 3 changes; by changing the swash plate angle, the displacement of the plunger pump can also be changed, so that the excitation amplitude of the double-acting hydraulic cylinder 3 changes. Specifically, the alternating flow distribution pump 1 can use a Chinese invention patent (authorization announcement number: CN104763604B) disclosed in a type of alternating flow distribution pump for controlling a hydraulic excitation system. In addition, in addition to the specific structure of the alternating flow distribution pump described above, the alternating flow distribution pump 1 can also use a hydraulic control pump disclosed in a Chinese invention patent (application publication number: CN115306666 A).

[0052] During the excitation process, the alternating flow distribution pump 1 itself can only roughly control the excitation amplitude. In the present application, a servo valve 2 is set between the alternating flow distribution pump 1 and the double-acting hydraulic cylinder 3. The servo valve 2 is preferably an electro-hydraulic servo valve, and the opening of its valve port is positively correlated with the control current of the servo valve 2. By adjusting the control current of the servo valve 2, the bidirectional liquid flow rate (liquid flow rate of oil port A and oil port B) to the double-acting hydraulic cylinder 3 can be changed. The dynamic response of the servo valve 2 is fast and the control accuracy is high. Therefore, the actual displacement signal is compared with the target displacement signal by the controller 5 to obtain the deviation between the target displacement signal and the actual displacement signal, and the deviation control signal is obtained. The control current of the servo valve 2 is controlled according to the deviation control signal, and then the valve port opening of the servo valve 2 is adjusted, so that the bidirectional flow input to the double-acting hydraulic cylinder 3 by the alternating flow distribution pump 1 through the servo valve 2 is synchronously reduced, thereby realizing the offset compensation of the displacement and speed of the double-acting hydraulic cylinder 3, and realizing the precise control of the excitation amplitude through the servo valve 2, ensuring that the displacement of the double-acting hydraulic cylinder 3 meets the set target and does not deviate. In addition, see Figure 1 The servo valve 2 is a three-position four-way electromagnetic reversing valve. Since the alternating flow distribution pump 1 itself can generate alternating fluid flow, the servo valve 2 only needs to be adjusted at a larger opening in one direction when controlling the alternating fluid flow. The valve core of the servo valve 2 does not need to move alternately in positive and negative directions near the zero position like a pure valve-controlled excitation system, that is, the servo valve 2 will not be in the upper position and the lower position ( Figure 1 The servo valve 2 is switched back and forth alternately in the direction shown in the figure, thereby avoiding excessive throttling loss caused by the valve port opening of the servo valve 2 being too small during the switching process; and since the servo valve 2 only needs to adjust the valve port opening in one direction, the servo valve 2 can also use a two-position four-way electromagnetic reversing valve. The servo valve 2 is diverse, as long as it has the function of adjusting the valve port opening in one direction.

[0053] Figure 3 Figure 1 is the time-displacement motion characteristic of the hydraulic cylinder (double-acting hydraulic cylinder 3) controlled by the alternating flow pump 1. The solid line is the actual displacement curve of the hydraulic cylinder directly controlled by the alternating flow pump 1, and the dotted line is the target displacement curve of the hydraulic cylinder controlled by the alternating flow pump 1. The target displacement curve is the ideal displacement curve. When there is a deviation between the actual displacement curve and the target displacement curve at the same time, it is necessary to control the valve opening of the servo valve 2 to control the bidirectional flow rate to the double-acting hydraulic cylinder 3, thereby adjusting the displacement speed of the double-acting hydraulic cylinder 3. The displacement of the double-acting hydraulic cylinder 3 has positive and negative values, and its displacement speed also has positive and negative values. See Figure 1. Figure 3 ,According to the positive and negative changes of displacement velocity, the target displacement curve is divided into quadrant I, quadrant II, quadrant III and quadrant IV from left to right. Figure 4 For Figure 3 Corresponding displacement-velocity motion characteristics, and corresponding Figure 3The quadrants are divided, wherein, in the I and IV quadrants, the target speed is positive. When the actual speed is greater than the target speed, the valve port opening of the servo valve 2 needs to be controlled to become smaller to reduce the displacement change amplitude of the double-acting hydraulic cylinder 3. When the actual speed is less than the target speed, the valve port opening of the servo valve 2 is controlled to become larger to increase the displacement change amplitude of the double-acting hydraulic cylinder 3. In the II and III quadrants, the target speed is negative. When the actual speed is greater than the target speed, the valve port opening of the servo valve 2 needs to be controlled to become larger to increase the displacement change amplitude of the double-acting hydraulic cylinder 3. When the actual speed is less than the target speed, the valve port opening of the servo valve 2 is controlled to become smaller to reduce the displacement change amplitude of the double-acting hydraulic cylinder 3. Different control methods are adopted according to different quadrant partitions to compensate for the deviation between the target displacement and the actual displacement, so that the actual displacement curve can match the actual displacement, that is, different deviation control signals are output according to different quadrant partitions, as follows:

[0054] Obtain target speed according to target displacement signal;

[0055] If the target speed is greater than or equal to 0, the deviation is used as the deviation control signal; if the target speed is less than 0, the inverted deviation is used as the deviation control signal;

[0056] The control current of the servo valve 2 is adjusted according to the deviation control signal to adjust the valve opening of the servo valve 2 and perform offset compensation on the displacement and speed of the double-acting hydraulic cylinder 3.

[0057] Specifically, the controller 5 includes a PID controller, which converts the deviation control signal into a control quantity through linear combination of proportion, integration and differentiation, thereby adjusting the control current of the servo valve 2 according to the control quantity to be able to adjust the valve opening of the servo valve 2. The PID control algorithm is simple, robust and reliable.

[0058] It should be noted that in the process of adjusting the displacement of the double-acting hydraulic cylinder 3, there may be a situation where it is necessary to adjust the valve opening of the servo valve 2 to increase, and at this time the valve opening of the servo valve 2 is already at the maximum state. Therefore, in this state, when the controller 5 recognizes that the control current of the servo valve 2 has reached the maximum value, the controller 5 controls the cylinder speed and / or the swash plate angle of the alternating flow distribution pump 1, that is, increases the maximum flow output by the alternating flow distribution pump 1, thereby changing the maximum amplitude of the displacement curve of the double-acting hydraulic cylinder 3, so that the servo valve 2 can continue to perform offset compensation for the displacement and speed of the double-acting hydraulic cylinder 3.

[0059] See also Figure 4When the displacement is near zero, the speed is extreme (maximum or minimum), that is, the speed is fast, and when the displacement reaches the extreme (maximum or minimum), the speed may be reversed and the speed is slow. The control requirements under these two control states are quite different, so Figure 4 The target displacement curve of the hydraulic cylinder is segmented according to the speed, that is, each quadrant is divided into two sections according to the speed, thus forming Figure 5 As shown in the ① to ⑧ segments, for segments ①, ④, ⑤, and ⑧, the output flow of the alternating flow pump 1 is relatively large, and the double-acting hydraulic cylinder 3 is in a state of relatively fast movement. Therefore, in this case, the PID controller is set to a smaller proportional coefficient parameter to prevent the adjustment range from being too large and causing overshoot; for segments ②, ③, ⑥, and ⑦, the output flow of the alternating flow pump 1 is relatively small, and the double-acting hydraulic cylinder 3 is in a state of relatively slow movement, and its movement speed is close to 0. Therefore, in this case, the PID controller is set to a larger proportional coefficient parameter to increase the adjustment effect. Correspondingly, the PID controller is a segmented PID controller, which performs the following operations:

[0060] When the absolute value of the target speed is greater than or equal to a set value, the proportional parameter of the segmented PID controller is set to a first proportional coefficient;

[0061] When the absolute value of the target speed is less than a set value, the proportional parameter of the segmented PID controller is set to a second proportional coefficient;

[0062] The first proportional coefficient is smaller than the second proportional coefficient.

[0063] As a first specific embodiment of the hydraulic excitation bias adjustment device of the present invention, see Figure 5The target sinusoidal curve (hydraulic cylinder displacement-time curve) is composed of a target frequency and a target amplitude. The flow rate of the alternating fluid output by the alternating flow pump 1 is controlled by the rotating flow plate speed, the cylinder speed and the swash plate angle, and the alternating fluid output by the alternating flow pump 1 is input into the double-acting hydraulic cylinder 3 through the servo valve 2. The valve opening of the servo valve 2 is controlled to adjust the size of the two-way flow to the double-acting hydraulic cylinder 3. During the excitation process, the actual displacement of the double-acting hydraulic cylinder 3 is monitored by the displacement sensor 4 to form an actual displacement curve, which is compared with the target sinusoidal curve, and the target The target speed is obtained by differentiating the displacement signal. If the target speed is greater than or equal to 0, the deviation between the displacement signal and the actual displacement signal is directly used as the deviation control signal; if the target speed is less than 0, the deviation is inverted as the deviation control signal. The segmented PID controller converts the deviation control signal into a control quantity through linear combination according to the proportion, integration and differentiation, and thus adjusts the control current of the servo valve 2 according to the control quantity to be able to adjust the valve opening of the servo valve 2. Different proportional coefficient parameters are used according to the absolute value of the target speed to achieve offset compensation for the displacement and speed of the double-acting hydraulic cylinder 3.

[0064] It should be noted that during the hydraulic excitation process, the phase of the actual output flow of the alternating flow distribution pump 1 will deviate to a certain extent from the target sinusoidal curve. Under long-term excitation, using the target sinusoidal curve as the control target will cause the phase difference between the actual displacement curve of the double-acting hydraulic cylinder 3 and the target sinusoidal curve to increase. In particular, when the speed zero point position of the target sinusoidal curve and the actual displacement curve differs greatly, it is difficult to compensate by controlling the servo valve 2. As a preferred embodiment of the hydraulic excitation bias adjustment device of the present invention, see Figure 7 The controller 5 of the hydraulic excitation bias adjustment device of the present invention further includes the following operations to identify the phase difference between the actual displacement curve and the target sinusoidal curve and control the phase compensation:

[0065] The target sinusoidal curve of the displacement of the double-acting hydraulic cylinder 3 is obtained, and the actual displacement signal of the double-acting hydraulic cylinder 3 is sampled multiple times in each cycle to form an actual displacement curve. The phase difference between the target sinusoidal curve of the displacement of the double-acting hydraulic cylinder 3 and the actual displacement curve is calculated based on the multiple sampling results to control the servo valve 2 for phase correction in the next cycle.

[0066] Among them, the error err between the target sinusoidal curve and the actual displacement curve can be described by the variance, that is:

[0067]

[0068] Among them, n is the number of sampling points in one cycle, i is the sampling sequence number, A is the amplitude of the target sine curve, x iis the actual displacement signal of the double-acting hydraulic cylinder 3 sampled for the i-th time;

[0069] By taking the partial derivative of ψ with respect to the error err, we can obtain:

[0070]

[0071] When the above equation is zero, the error err reaches its minimum value. Based on this, the equation for calculating the phase difference ψ can be obtained as follows:

[0072]

[0073] In order to better reflect the displacement compensation effect of the hydraulic excitation bias adjustment device of the present invention on the double-acting hydraulic cylinder 3 during the excitation process, as shown in FIG. Figure 8 As shown in FIG, “no control” represents the displacement curve of the hydraulic cylinder directly controlled by the alternating flow distribution pump 1, and “control” represents the displacement curve of the hydraulic cylinder controlled by the hydraulic excitation bias adjustment device of the present invention. It can be clearly seen that under the control of the hydraulic excitation bias adjustment device of the present invention, the displacement curve of the hydraulic cylinder is more symmetrical than that of the direct control of the alternating flow distribution pump 1. Further, as Figure 9 The change trend of the median displacement of the hydraulic cylinder over time under the two control modes shown is that compared with the direct control of the alternating flow distribution pump 1, the median displacement of the hydraulic cylinder under the control of the hydraulic excitation bias adjustment device of the present invention gradually stabilizes, so that the displacement of the hydraulic cylinder meets the set target and can effectively suppress the drift phenomenon, that is, avoid the displacement of the hydraulic cylinder from being offset. At the same time, during the hydraulic excitation process, the hydraulic excitation bias adjustment device of the present invention controls the movement of the valve core of the servo valve 2 to perform bias adjustment. According to the throttle valve principle, the smaller the valve opening, the more obvious the throttling effect and the greater the throttling loss. During the bias compensation process, the servo valve 2 of the hydraulic excitation bias adjustment device of the present invention has its valve core basically in a large unidirectional opening, and the alternating fluid flow is generated by the alternating flow distribution pump 1. Therefore, as shown in FIG. Figure 10 As shown, the valve core displacement of the servo valve 2 of the hydraulic excitation bias adjustment device of the present invention accounts for more than 70% of the full stroke, and most of them are above 80%. During the bias adjustment process, the throttling loss of the hydraulic excitation bias adjustment device of the present invention is relatively small.

[0074] Furthermore, the present invention also provides a hydraulic excitation system, which includes the hydraulic excitation bias adjustment device provided by the present invention and has all its beneficial effects, which will not be described in detail here.

[0075] Corresponding to the hydraulic excitation bias adjustment device of the present invention, the present invention further provides a hydraulic excitation bias adjustment method, which can be preferably implemented using the hydraulic excitation bias adjustment device of the present invention. Specifically, the servo valve 2 is arranged between the alternating flow distribution pump 1 for outputting an alternating fluid flow and the double-acting hydraulic cylinder 3. The hydraulic excitation bias adjustment method of the present invention includes the following steps:

[0076] Obtaining the actual displacement signal of the double-acting hydraulic cylinder 3 and obtaining the deviation between the target displacement signal and the actual displacement signal;

[0077] According to the deviation control, a deviation control signal is output to adjust the valve opening of the servo valve 2 and perform offset compensation on the displacement and speed of the double-acting hydraulic cylinder 3.

[0078] Specifically, obtaining the deviation between the target displacement signal and the actual displacement signal includes the following steps:

[0079] Obtain target speed according to target displacement signal;

[0080] For target speed judgment, if the target speed is greater than or equal to 0, the deviation is used as the deviation control signal; if the target speed is less than 0, the deviation is inverted as the deviation control signal;

[0081] The control current of the servo valve 2 is adjusted according to the deviation control signal to adjust the valve opening of the servo valve 2 and perform offset compensation on the displacement and speed of the double-acting hydraulic cylinder 3.

[0082] Preferably, the control current of the servo valve 2 is adjusted according to the deviation control signal by PID control, wherein the PID control adopts segmented PID control, including the following steps:

[0083] When the absolute value of the target speed is greater than or equal to the set value, the proportional parameter of the segmented PID control is set to the first proportional coefficient;

[0084] When the absolute value of the target speed is less than the set value, the proportional parameter of the segmented PID control is set to the second proportional coefficient;

[0085] The first proportional coefficient is smaller than the second proportional coefficient.

[0086] Further preferably, the method further comprises the following steps:

[0087] The target sinusoidal curve of the displacement of the double-acting hydraulic cylinder 3 is obtained. The actual displacement signal of the double-acting hydraulic cylinder 3 is sampled multiple times in one cycle to form an actual displacement curve. The phase difference between the target sinusoidal curve of the displacement of the double-acting hydraulic cylinder 3 and the actual displacement curve is calculated based on the multiple sampling results to control the servo valve 2 for phase correction in the next cycle. The formula for calculating the phase difference ψ is as follows:

[0088]

[0089] Among them, n is the number of sampling points in one cycle, i is the sampling sequence number, and x i is the actual displacement signal of the double-acting hydraulic cylinder 3 sampled for the i-th time.

[0090] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0091] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. To avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0092] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A hydraulic excitation bias adjustment device, characterized in that: include: A servo valve (2), the servo valve (2) being arranged between the double-acting hydraulic cylinder (3) and the alternating flow distribution pump (1) so as to be able to adjust the flow rate of the alternating fluid flow inputted from the alternating flow distribution pump (1) into the double-acting hydraulic cylinder (3); A displacement sensor (4), the displacement sensor (4) being used to detect an actual displacement signal of the double-acting hydraulic cylinder (3); A controller (5), the controller (5) being electrically connected to the displacement sensor (4) and the servo valve (2), respectively, and the controller (5) being configured to perform the following operations: Acquire the actual displacement signal and obtain a deviation between the target displacement signal and the actual displacement signal; acquiring a target speed according to the target displacement signal; If the target speed is greater than or equal to 0, the deviation is used as a deviation control signal; If the target speed is less than 0, the deviation is inverted as the deviation control signal; Regulating the control current of the servo valve (2) according to the deviation control signal to adjust the valve opening of the servo valve (2) and perform offset compensation on the displacement and speed of the double-acting hydraulic cylinder (3); The controller (5) includes a PID controller, which adjusts the control current of the servo valve (2) according to the deviation control signal, and the PID controller is a segmented PID controller, which performs the following operations: When the absolute value of the target speed is greater than or equal to a set value, the proportional parameter of the segmented PID controller is set to a first proportional coefficient; When the absolute value of the target speed is less than a set value, the proportional parameter of the segmented PID controller is set to a second proportional coefficient; The first proportional coefficient is smaller than the second proportional coefficient.

2. The hydraulic excitation bias adjustment device according to claim 1, characterized in that: The controller (5) is further configured to perform the following operations: Obtain the target sinusoidal curve of the displacement of the double-acting hydraulic cylinder (3), sample the actual displacement signal of the double-acting hydraulic cylinder (3) multiple times in each cycle to form an actual displacement curve, calculate the phase difference between the target sinusoidal curve of the displacement of the double-acting hydraulic cylinder (3) and the actual displacement curve based on the multiple sampling results, and control the servo valve (2) to perform phase correction in the next cycle, wherein the calculated phase difference of The formula is as follows: in, n is the number of sampling points in one cycle, i is the sampling sequence number, x i For the i The actual displacement signal of the double-acting hydraulic cylinder (3) is sampled.

3. A hydraulic excitation system, characterized in that: It comprises the hydraulic excitation bias adjustment device according to any one of claims 1-2.

4. A hydraulic excitation bias adjustment method, characterized in that: A servo valve (2) is provided between an alternating flow distribution pump (1) for outputting an alternating fluid flow and a double-acting hydraulic cylinder (3). The method comprises the following steps: Acquiring an actual displacement signal of the double-acting hydraulic cylinder (3) and obtaining a deviation between a target displacement signal and the actual displacement signal; acquiring a target speed according to the target displacement signal; The target speed is judged, if the target speed is greater than or equal to 0, the deviation is used as the deviation control signal; if the target speed is less than 0, the deviation is negated and used as the deviation control signal; Regulating the control current of the servo valve (2) according to the deviation control signal to adjust the valve opening of the servo valve (2) and perform offset compensation on the displacement and speed of the double-acting hydraulic cylinder (3); Outputting a deviation control signal according to the deviation control to adjust the valve opening of the servo valve (2) and perform offset compensation on the displacement and speed of the double-acting hydraulic cylinder (3); The control current of the servo valve (2) is adjusted according to the deviation control signal through PID control, and the PID control adopts segmented PID control, including the following steps: When the absolute value of the target speed is greater than or equal to a set value, the proportional parameter of the segmented PID control is set to a first proportional coefficient; When the absolute value of the target speed is less than a set value, the proportional parameter of the segmented PID control is set to a second proportional coefficient; The first proportional coefficient is smaller than the second proportional coefficient.

5. The hydraulic excitation bias adjustment method according to claim 4, characterized in that: The method further comprises the following steps: The target sinusoidal curve of the displacement of the double-acting hydraulic cylinder (3) is obtained, the actual displacement signal of the double-acting hydraulic cylinder (3) is sampled multiple times in one cycle to form an actual displacement curve, and the phase difference between the target sinusoidal curve of the displacement of the double-acting hydraulic cylinder (3) and the actual displacement curve is calculated based on the multiple sampling results to control the servo valve (2) to perform phase correction in the next cycle, wherein the calculated phase difference of The formula is as follows: in, n is the number of sampling points in one cycle, i is the sampling sequence number, x i For the i The actual displacement signal of the double-acting hydraulic cylinder (3) is sampled.

Images