High-precision liquid phase pump control system and control method based on linear motor

Abstract

The invention discloses a high-precision liquid phase pump control system and method based on a linear motor. The system comprises the linear motor, a driver, a motion controller, a peripheral control device and an upper computer. Wherein the upper computer sends a control instruction to the motion controller; the motion controller is used for generating a PWM pulse signal according to a control instruction sent by the upper computer; according to the control instruction sent by the upper computer and the collected pressure signal of the linear motor, generating a proportion parameter; the PWM pulse signal and the proportion parameter are sent to a linear motor; and the linear motor drives the hydraulic cylinder body to move through the driver according to the proportion parameter and the PWM pulse signal sent by the motion controller. And pressure fluctuation and pulsation are effectively restrained, and high-precision pressure stable control over the whole machine is achieved.

Description

Technical Field

[0001] The present invention relates to a high-precision liquid-phase pump control system and control method based on a linear motor, belonging to the technical field of electronic engineering. Background Art

[0002] At present, foreign instrument suppliers have successively launched ultra-high performance liquid chromatography (UHPLC for short) with higher resolution, faster analysis speed, and higher sensitivity, and have been quickly applied to food safety, pharmaceuticals, environmental testing, scientific research and other fields. Such instruments can not only greatly improve the work efficiency of chromatographers, but also significantly reduce the consumption of solvents and samples, greatly reduce the demand for environmental resources, and significantly save costs. The high-precision liquid-phase pump is the core component of UHPLC. Its main function is to continuously and stably transport samples and solvents, ensure the flow rate and mixing effect of samples on the chromatographic column. Its indicators such as pressure, flow rate, flow accuracy, and pressure pulsation rate are the core for promoting the chromatographic column to achieve efficient separation, and determine the final performance of UHPLC.

[0003] The core technology of China's UHPLC industry is insufficient and highly dependent on imports. For high-precision liquid-phase pump products, leading foreign brands such as Waters, Agilent, and Thermo Fisher have always been in the leading position in achieving core technical indicators, and their core indicators such as pressure, flow rate, flow accuracy, and pressure pulsation rate of their products far exceed those in China.

[0004] Based on the double-cylinder series structure driven by a linear module to drive the plunger, a linear motor is used to realize the reciprocating position drive of the plunger, replacing the direct drive method of a rotary motor + lead screw, reducing the original structural space accuracy error, and improving the response speed of the drive components. A control method is required to improve the flow accuracy of the liquid-phase pump and the overall pressure stability. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: to overcome the deficiencies of the prior art and provide a high-precision liquid-phase pump control system and control method based on a linear motor.

[0006] The technical solution of the present invention is:

[0007] The present invention discloses a high-precision liquid-phase pump control system based on a linear motor, including: a linear motor, a driver, a motion controller, peripheral control components, and a host computer; wherein,

[0008] The host computer sends control instructions to the motion controller;

[0009] The motion controller generates a PWM pulse signal according to the control instructions sent by the host computer; generates a proportional parameter according to the control instructions sent by the host computer and the collected pressure signal of the linear motor; and sends the PWM pulse signal and the proportional parameter to the linear motor;

[0010] The linear motor drives the hydraulic cylinder block to move through the driver according to the proportional parameter and PWM pulse signal sent by the motion controller.

[0011] Further, in the above system, the motion controller includes a main controller and a slave controller; the main controller is connected to the upper computer, and the main controller and the slave controller perform data interaction; the main controller and the slave controller respectively control a linear motor; the main controller receives the control instruction from the upper computer and forwards it to the slave controller.

[0012] Further, in the above system, the proportional parameter is generated according to the control instruction sent by the upper computer and the collected pressure signal of the linear motor, specifically:

[0013] S31. Obtain the pressure data set P;

[0014] S32. Calculate the average pressure within the entire period

[0015] S33. Calculate the mean square deviation δ between the pressure data set P and the average pressure ;

[0016] S34. If the mean square deviation δ is greater than the set mean square deviation δ s , perform curve fitting on the pressure data set P; go to step S35; otherwise, go to step S31;

[0017] S35. If the control instruction is for a single pump, calculate the single-pump pressure closed-loop proportional parameter according to the curve fitting result; if the control instruction is for a double pump, calculate the double-pump liquid path mixing proportional parameter according to the curve fitting result.

[0018] Further, in the above system, the single-pump pressure closed-loop proportional parameter is specifically:

[0019] If the slope of the fitting curve is continuously decreasing, the proportional parameter k p is:

[0020]

[0021] If the slope of the fitting curve is continuously increasing, the proportional parameter k p is:

[0022]

[0023] If the slope of the fitting curve fluctuates between increasing and decreasing, record the peak point pressures {p H0 , p H1 ... p Hk} and the trough point pressures {p L0 , pL1 ……p Lm}, then the proportional parameter k p is:

[0024]

[0025] wherein, k p0 is the initial ratio, K is the ratio increase base coefficient, k is the number of wave peaks, and m is the number of wave valleys.

[0026] Further, in the above system, the dual-pump liquid path mixing ratio parameter is specifically:

[0027] Divide the pressure data set P into the pressure data set P1 and the pressure data set P2 evenly;

[0028] Determine whether the fitting curve slope of the data set P1 or the data set P2 is fluctuating; if so, modify and update the corresponding proportional parameter compensation to K p ; otherwise, keep the current proportional parameter; wherein, k p0 is the initial ratio, K is the ratio increase base coefficient, k is the number of wave peaks, and m is the number of wave valleys.

[0029] The present invention discloses a high-precision liquid-phase pump control method based on a linear motor, comprising the following steps:

[0030] S1. Set up a flow path branch;

[0031] S2. Obtain the pressure value of the hydraulic cylinder body;

[0032] S3. Calculate the pulsation rate according to the pressure value;

[0033] S4. Judge whether the pulsation rate meets the requirements. If so, enter step S2; if not, enter step S5;

[0034] S5. Calculate the pressure closed-loop proportional parameter according to the flow path branch and the pressure value;

[0035] S6. Adjust the pressure of the hydraulic cylinder body according to the pressure closed-loop proportional parameter, and enter step S2.

[0036] Further, in the above method, the calculation of the pressure closed-loop proportional parameter according to the flow path branch and the pressure value is specifically:

[0037] S71. Obtain the pressure data set P;

[0038] S72. Calculate the average pressure within the entire cycle

[0039] S73. Calculate the pressure data set P and the average pressure The mean square error δ;

[0040] S74. If the mean square error δ is greater than the set mean square error δ s , perform curve fitting on the pressure data set P and go to step S75; otherwise, go to step S71;

[0041] S75. If the flow branch is one-way, calculate the single-pump pressure closed-loop proportional parameter according to the curve fitting result; if the flow branch is two-way, calculate the double-pump liquid path mixing ratio parameter according to the curve fitting result.

[0042] Furthermore, in the above method, the pulsation rate is specifically:

[0043] m ∈ =(p max -p min ) / p mean

[0044] where m ∈ is the pulsation rate, p max is the highest pressure in the current cycle, p min is the lowest pressure in the current cycle, and p mean is the average pressure value.

[0045] The beneficial effects of the present invention compared with the prior art are as follows:

[0046] (1) The present invention realizes the high dynamic response and high steady-state accuracy of the high-precision liquid pump through the linear motor drive control method, eliminates the clearance error of the reciprocating motion of the transmission mechanism such as the lead screw and the influence of the inertia and resistance moment of the transmission mechanism, and improves the transmission efficiency, dynamic response speed and positioning accuracy of the mechanism.

[0047] (2) The present invention realizes the precise motion control and high-speed closed-loop gain parameter feedback of the high-precision liquid pump through the integrated control system, ensuring high-precision, low-pulsation and dynamic response of the single-pump output flow.

[0048] (3) Different from the conventional method of determining the compression stroke of the medium through the compression coefficient, the present invention effectively improves the single-pump pressure stability through the single-pump beat-constrained pressure stability adaptive algorithm.

[0049] (4) The present invention compensates through the adaptive algorithm for the mutual disturbance caused by the double-pump output, significantly improves the pressure stability of the system under the mixing of the double-pump output medium, effectively suppresses the pressure fluctuation and pulsation, and realizes the high-precision pressure stability control of the whole machine. Description of the Drawings

[0050] Figure 1 is the system composition block diagram described in the embodiment of the present invention;

[0051] Figure 2It is a block diagram of the control system described in the embodiments of the present invention. Detailed implementation manners

[0052] The following further elaborates on the present invention patent in detail in conjunction with the accompanying drawings and specific implementation manners.

[0053] The present invention discloses a high-precision liquid-phase pump control system based on a linear motor, including: a linear motor, a driver, a motion controller, peripheral control components, and a host computer; wherein,

[0054] The host computer sends control instructions to the motion controller;

[0055] The motion controller generates a PWM pulse signal according to the control instruction sent by the host computer; generates a proportional parameter according to the control instruction sent by the host computer and the collected pressure signal of the linear motor; and sends the PWM pulse signal and the proportional parameter to the linear motor;

[0056] The linear motor drives the hydraulic cylinder body to move through the driver according to the proportional parameter and the PWM pulse signal sent by the motion controller.

[0057] Preferably, the motion controller includes a main controller and a slave controller; the main controller is connected to the host computer, and the main controller exchanges data with the slave controller; the main control and the slave controller respectively control a linear motor; the main controller receives the control instruction from the host computer and forwards it to the slave controller.

[0058] Preferably, generating a proportional parameter according to the control instruction sent by the host computer and the collected pressure signal of the linear motor is specifically as follows:

[0059] S31. Obtain the pressure data set P;

[0060] S32. Calculate the average pressure within the entire period

[0061] S33. Calculate the mean square deviation δ between the pressure data set P and the average pressure ;

[0062] S34. If the mean square deviation δ is greater than the set mean square deviation δ s , perform curve fitting on the pressure data set P; enter step S35; otherwise, enter step S31;

[0063] S35. If the control instruction is for a single pump, calculate the single-pump pressure closed-loop proportional parameter according to the curve fitting result; if the control instruction is for a double pump, calculate the double-pump liquid path mixing proportional parameter according to the curve fitting result.

[0064] Preferably, the single-pump pressure closed-loop proportional parameter is specifically as follows:

[0065] If the slope of the fitting curve continuously decreases, the proportionality parameter k p is:

[0066]

[0067] If the slope of the fitting curve continuously increases, the proportionality parameter k p is:

[0068]

[0069] If the slope of the fitting curve fluctuates between increasing and decreasing, record the peak point pressures {p H0 , p H1 ... p Hk} and the trough point pressures {p L0 , p L1 ... p Lm}, then the proportionality parameter k p is:

[0070]

[0071] where k p0 is the initial ratio, K is the ratio increase base coefficient, k is the number of peaks, and m is the number of troughs.

[0072] Preferably, the dual-pump liquid path mixing ratio parameter is specifically:

[0073] Divide the pressure data set P into the pressure data set P1 and the pressure data set P2 evenly;

[0074] Determine whether the slope of the fitting curve of the data set P1 or the data set P2 fluctuates; if so, compensate, modify, and update the corresponding ratio parameter to K p ; otherwise, keep the current ratio parameter; where k p0 is the initial ratio, K is the ratio increase base coefficient, k is the number of peaks, and m is the number of troughs.

[0075] The present invention discloses a high-precision liquid-phase pump control method based on a linear motor, which includes the following steps:

[0076] S1. Set the flow path branches;

[0077] S2. Obtain the pressure value of the hydraulic cylinder block;

[0078] S3. Calculate the pulsation rate according to the pressure value;

[0079] S4. Judge whether the pulsation rate meets the requirements. If so, enter step S2; if not, enter step S5;

[0080] S5. Calculate the pressure closed-loop proportional parameter according to the flow path branch and the pressure value;

[0081] S6. Adjust the pressure of the hydraulic cylinder block according to the pressure closed-loop proportional parameter, and enter step S2.

[0082] Preferably, calculating the pressure closed-loop proportional parameter according to the flow path branch and the pressure value specifically includes:

[0083] S71. Obtain the pressure data set P;

[0084] S72. Calculate the average pressure value within the entire cycle

[0085] S73. Calculate the mean square deviation δ between the pressure data set P and the average pressure ;

[0086] S74. If the mean square deviation δ is greater than the set mean square deviation δ s , perform curve fitting on the pressure data set P and enter step S75; otherwise, enter step S71;

[0087] S75. If the flow branch is one-way, calculate the single-pump pressure closed-loop proportional parameter according to the curve fitting result; if the flow branch is two-way, calculate the double-pump liquid path mixing ratio parameter according to the curve fitting result.

[0088] Preferably, the pulsation rate is specifically:

[0089] m ∈ =(p max -p min ) / p mean

[0090] where m ∈ is the pulsation rate, p max is the highest pressure within the current cycle, p min is the lowest pressure within the current cycle, and p mean is the average pressure value.

[0091] Embodiment

[0092] In this embodiment, relying on a high-precision ultra-high pressure liquid pump, the pump is as Figure 1As shown in the figure, it is composed of two sets of independent pump liquid ends connected in series, called Pump A and Pump B. Each of them is composed of two cylinders in two series liquid paths. Each cylinder is driven by an independent linear motor, called A-PRI cylinder, A-ACC cylinder, B-PRI cylinder, and B-ACC cylinder respectively. Among them, A-PRI and A-ACC cooperate with each other according to a certain time sequence to realize the liquid suction and discharge processes of Pump A. B-PRI and B-ACC cooperate with each other according to a certain time sequence to realize the liquid suction and discharge processes of Pump B. The above processes need to ensure the consistency of the flow accuracy and low pulsation rate of Pump A and Pump B themselves. At the same time, there are certain constraints on the flow relationship during the coordinated operation of Pump A and Pump B, and it is necessary to ensure the consistency of the combined flow accuracy and low pulsation rate of the two. This constraint also applies to the high-pressure (150 MPa) condition.

[0093] As Figure 1 shown in the figure, this embodiment provides a high-precision liquid-phase pump control system based on a linear motor, including:

[0094] The linear motor and driver, motion controller, peripheral control devices, and control host computer are composed.

[0095] The linear motor and driver are used to drive the A-PRI cylinder, A-ACC cylinder, B-PRI cylinder, and B-ACC cylinder to move to realize the liquid delivery in a single cylinder.

[0096] The motion controller is an embedded control system based on ARM. The motion controller controls two linear motors by means of PWM pulses, including parameters such as speed, acceleration, and position, to generate the time-sequence coordinated actions of the PRI cylinder and ACC cylinder, corresponding to the movements of the two cylinders to realize the single-pump liquid output. The motion controller is connected to peripheral devices to meet the requirements of high-speed signal acquisition and data processing of peripheral devices. The entire liquid-phase pump system contains two identical motion controllers, divided into a main controller and a slave controller. The two controllers can perform data interaction through communication. In addition, the main controller is connected to the host computer.

[0097] One pressure sensor is arranged in each of the A-PRI cylinder, A-ACC cylinder, B-PRI cylinder, and B-ACC cylinder to monitor the real-time pressure of each cylinder and feedback the pressure signal to the corresponding motion controller.

[0098] The peripheral control devices include six-way valves, selection valves, pre-degassing pumps, post-cleaning pumps, etc., all of which are connected to the main controller to realize the linkage logic of control to form the entire ultra-high-pressure high-precision liquid-phase pump control system.

[0099] A high-precision liquid-phase pump control method provided by this embodiment includes:

[0100] 1. Control system initialization

[0101] Initialize the motion controller, set parameters and configure communication.

[0102] 2. Data interaction reception and analysis

[0103] The target flow, flow branch selection and other information are set through the host computer. The above information is transmitted to the main controller via Ethernet. The main controller parses the data, executes the system's peripheral control and the linear motor execution data of pump A, and forwards the linear motor execution data of pump B to the slave controller at the same time; after the slave controller receives the above data, the linear motor execution data of pump B is executed.

[0104] 3. High-precision and high-resolution time trigger control

[0105] The master and slave controllers use the system beat timer of the ARM controller to generate a 1ms timing interrupt as the trigger reference for the linear motor drive beat of pump A and pump B.

[0106] 4. Real-time speed control and precise position tracking of linear motor and driver motion curve

[0107] The linear motor driver is set as a three-layer closed loop of current, speed, and position. The position closed loop is the outermost closed loop control. By collecting high-precision grating scale values ​​for feedback, it can ensure the priority control of the reached position; the speed closed loop belongs to the inner closed loop, which is responsible for the stable operation of the motor in the process of reaching the specified position; the current loop is the innermost closed loop, which is responsible for setting the motor PID adjustment, thereby controlling the motor torque and achieving fast dynamic response. Due to the requirements for dynamic compensation and adaptive adjustment of the motor motion process, the controller inputs PWM signals to the driver according to the timing beat described in 3 above, which can ensure that the motor runs a specified number of revolutions according to a specific acceleration, deceleration or uniform speed curve. If the running trajectory needs to be changed during operation, it is necessary to trigger the enable instruction at the current position and rewrite the new motion trajectory, so that the motor can switch between different states of motion at will.

[0108] 5. Single pump pressure closed-loop gain parameter feedback and state compensation update

[0109] like Figure 2As shown, both pump A and pump B achieve stable liquid output through the rhythmic linkage between the PRI cylinder and the ACC cylinder. During the process segment (1), the ACC cylinder continuously and stably outputs liquid at this time, while the PRI cylinder replenishes the liquid and compresses the replenished liquid. The goal of compression in place is that the pressure values of the PRI cylinder and the ACC cylinder are the same. This process requires calculating the numerical difference by the pressure sensors of their respective PRI cylinders and ACC cylinders, and using it as a feedback signal to determine whether the liquid in the ACC cylinder needs to be further compressed. Considering that under different medium mixing ratios and different system pressure values, the overall compression coefficient of the liquid in the hydraulic end is different, it is necessary to identify different states for dynamic compensation. The specific design implementation is as follows:

[0110] The pressure approximation control strategy for the PRI cylinder adopts a PI control algorithm based on parameter self-tuning, and automatically completes the update of the P control parameter through curve fitting and fluctuation deviation analysis of the pressure curve in the previous cycle. The implementation method is as follows:

[0111] Step S11: Set the initial ratio k p0 and integral k i ;

[0112] Step S12: Record the pressure data at fixed time intervals Δ t to obtain the pressure data set P, where:

[0113] P = {p0, p1, p2, ……, p n}

[0114] Step S13: Calculate the average pressure value within the entire cycle where:

[0115]

[0116] Step S14: Calculate the mean square deviation δ between the pressure data set P and the average pressure , where:

[0117]

[0118] If the mean square deviation δ is greater than the set δ s (default is 0.2 MPa), perform curve fitting and analysis on the pressure data set P:

[0119] If the slope of the fitting curve is continuously decreasing, then:

[0120]

[0121] If the slope of the fitting curve is continuously increasing, then:

[0122]

[0123] If the slope of the fitting curve fluctuates between increasing and decreasing, record the peak point pressure {p H0 , p H1 …… p Hk} and the trough point pressure {p L0 , p L1 …… p Lm}, then the proportional parameter k p :

[0124]

[0125] Step S15: Repeat steps S12 - S14 in each control cycle.

[0126] 6. Dual - pump liquid - path mixing

[0127] When pumps A and B act together, their discharged liquids are finally mixed in the mixer, and there is a phenomenon of mutual pressure disturbance, that is, the pulsation of the pressure in one path will affect the pressure in the other path. Algorithm supplementation is carried out on the main - pump element approximation strategy of single - pump actuation, and curve fitting is performed on the pressure data set P:

[0128] If the curve slope fluctuates, divide the pressure data set P into P1 and P2 for analysis. By determining whether the fitting curve slope of the P1 or P2 data set fluctuates, when fluctuations occur, the corresponding proportional parameter compensation is modified and updated as:

[0129]

[0130] When no fluctuations occur, the current proportional parameter is maintained.

[0131] In this embodiment, a high - precision liquid - phase pump control system and control method based on a linear motor include the following steps:

[0132] The flow accuracy RSD of the system is 0.06%, the pulsation rate is 0.3 MPa, and the maximum operating pressure of the system is 150 MPa. For example, in gradient elution operation, the change in the mixing ratio of phases A and B will cause a change in the column pressure. To ensure the smoothness of the gradient curve and the accuracy of the concentration ratio, the system pressure pulsation needs to be dynamically adjusted accordingly. Therefore, for the entire control system, the fast and accurate transmission of information flow must be realized to ensure that the concentration ratio in the gradient process operates stably according to the set method with high precision.

[0133] The change in the concentration ratio is reflected in the pulsation rate. Based on the goal of meeting the flow accuracy RSD ≤ 0.06% and the pulsation rate ≤ 0.3 MPa at a certain pressure, a high - speed information - flow transmission link is constructed among the high - precision grating scale, linear motor, pressure sensor, and main control system.

[0134] The grating scale information acquisition is feedback stream data. The grating scale position information is uploaded to the lower computer control system in real time. The data stream transmission mode is high-speed BISS-C transmission. The average instruction length is 20 bytes, and the information transmission rate is 1 Mbps:

[0135] T1 = 1 / ((1×

[10] ^6) / 8)×20 = 0.16 ms

[0136] The pressure sensors are connected in parallel. The feedback data frequency is 100 Hz. The pressure value changes transiently during the system movement. High-speed data transmission is required to ensure the accuracy of the collected pressure value. The data stream transmission mode is serial communication, the transmission rate is 115200 bps, and each pressure value information is 10 bytes. The transmission time of the pressure sensor is:

[0137] T2 = 1 / (115200 / 8)×10 = 0.70 ms

[0138] The timing feedback time of the pressure sensor is:

[0139] T3 = 1 / 100*1000 = 10 ms

[0140] Ensure that the information of multiple pressure sensors is all updated within the time of (T2 + T3), that is, within 10.7 ms.

[0141] The main control system runs in a program loop refresh. The single running cycle time is T4 = 5 ms.

[0142] Therefore, the entire information flow bus transmission cycle is max((T1 + T2 + T3), T4) = 10.86 ms

[0143] Under the linkage of the entire control link, 10.86 ms can meet the data stream update, ensuring the rapidity and accuracy of the entire execution process. The control pulsation rate, that is, the control two-phase mixing mass ratio (concentration ratio), provides a guarantee for ultra-high efficiency analysis.

[0144] In the project task book indicators, it is proposed that the system flow accuracy RSD = 0.06%, the pulsation rate is 0.3 MPa, and the maximum operating pressure of the system is 150 MPa.

[0145] The final experiment verifies that the measured flow value is 0.5002 ml / min at a set flow rate of 0.5 mL / min, and the accuracy error = 0.04%; the working pressure of the chromatographic analysis column is 100 MPa, and the pulsation rate is 0.223 MPa.

[0146] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present invention. After those skilled in the art have read the above content, various modifications and alternatives to the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.

[0147] The content not described in detail in the specification of the present invention belongs to the well-known technology of those skilled in the art.

Claims

1. A high-precision liquid-phase pump control system based on a linear motor, characterized in that Including: A linear motor, a driver, a motion controller, peripheral control devices, and a host computer; Among them, The host computer sends control instructions to the motion controller; The motion controller generates a PWM pulse signal according to the control instruction sent by the host computer; and generates a proportional parameter according to the control instruction sent by the host computer and the collected pressure signal of the linear motor; Send the PWM pulse signal and the proportional parameter to the linear motor; The linear motor drives the hydraulic cylinder body to move through the driver according to the proportional parameter and the PWM pulse signal sent by the motion controller.

2. The high-precision liquid-phase pump control system based on a linear motor according to claim 1, wherein The motion controller includes a main controller and a slave controller; the main controller is connected to the host computer, and the main controller exchanges data with the slave controller; the main controller and the slave controller respectively control a linear motor; the main controller receives the control instruction from the host computer and forwards it to the slave controller.

3. The high-precision liquid-phase pump control system based on a linear motor according to claim 1, wherein, The generating of the proportional parameter according to the control instruction sent by the host computer and the collected pressure signal of the linear motor is specifically as follows: S31. Obtain the pressure data set P; S32. Calculate the average pressure over the entire period S33. Calculate the mean square deviation δ between the pressure data set P and the mean pressure ; S34. If the mean square error δ is greater than the set mean square error δ s , perform curve fitting on the pressure data set P; proceed to step S35; otherwise, proceed to step S31; S35. If the control instruction is for a single pump, calculate the single-pump pressure closed-loop proportional parameter according to the curve fitting result; if the control instruction is for a double pump, calculate the double-pump liquid path mixing proportional parameter according to the curve fitting result.

4. A high-precision liquid-phase pump control system based on a linear motor according to claim 2, characterized in that, The single-pump pressure closed-loop proportional parameter is specifically: If the slope of the fitting curve continuously decreases, then the proportionality parameter k p is as follows: If the slope of the fitting curve continuously increases, then the proportionality parameter k p is: If the slope of the fitting curve fluctuates between an increase and a decrease, record the peak point pressure {p H0 , p H1 …… p Hk} and the trough point pressure {p L0 , p L1 …… p Lm}, then the proportionality parameter k p is: where k p0 is the initial ratio, K is the ratio increase base coefficient, k is the number of peaks, and m is the number of valleys.

5. A high-precision liquid-phase pump control system based on a linear motor according to claim 2, wherein, The double-pump liquid path mixing proportional parameter is specifically: Divide the pressure data set P into a pressure data set P1 and a pressure data set P2 evenly; Determine whether the slope of the fitting curve of dataset P1 or dataset P2 fluctuates; if so, compensate, modify, and update the corresponding proportional parameter to K p ; otherwise, keep the current proportional parameter; where k p0 is the initial ratio, K is the proportional increase base coefficient, k is the number of wave peaks, and m is the number of wave valleys.

6. A high-precision liquid-phase pump control method based on a linear motor, characterized in that Including the following steps: S1. Set the flow path branch; S2. Obtain the pressure value of the hydraulic cylinder body; S3. Calculate the pulsation rate according to the pressure value; S4. Judge whether the pulsation rate meets the requirement. If yes, go to step S2; if not, go to step S5; S5. Calculate the pressure closed-loop proportional parameter according to the flow path branch and the pressure value; S6. Adjust the pressure of the hydraulic cylinder body according to the pressure closed-loop proportional parameter, and go to step S2.

7. A high-precision liquid-phase pump control method based on a linear motor according to claim 6, characterized in that The calculating of the pressure closed-loop proportional parameter according to the flow path branch and the pressure value is specifically as follows: S71. Obtain the pressure data set P; S72. Calculate the average pressure over the entire period S73. Calculate the mean square deviation δ between the pressure data set P and the mean pressure ; S74. If the mean square error δ is greater than the set mean square error δ s , perform curve fitting on the pressure data set P and proceed to step S75; otherwise, proceed to step S71; S75. If the flow branch is one-way, calculate the single-pump pressure closed-loop proportional parameter according to the curve fitting result; if the flow branch is two-way, calculate the double-pump liquid path mixing proportional parameter according to the curve fitting result.

8. A high-precision liquid-phase pump control method based on a linear motor according to claim 6, characterized in that, The pulsation rate is specifically: m ∈ = (p max - p min ) / p mean where m ∈ is the pulsation rate, p max is the highest pressure in the current cycle, p min is the lowest pressure in the current cycle, p mean is the average pressure value.

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