Full closed-loop control method of high-frequency response valve

Abstract

The invention relates to the technical field of high-frequency response valves, in particular to a full-closed-loop control method of a high-frequency response valve. Comprising a motion controller, a grating ruler / magnetic grating ruler, a high-frequency response servo proportional valve and a motion controller, and the motion controller is matched with a motion control program. Wherein the motion controller obtains a speed instruction through operation according to a motion plan of the motion controller and an actual shaft position fed back by the grating ruler / magnetic grating ruler, and after the speed instruction and a proportional valve core position feedback value received by the motion controller in real time participate in valve core control closed-loop operation at the same time, current of a port A and a port B of the proportional valve is obtained and sent to the proportional valve; and the proportional valve opens the corresponding opening according to the real-time current of the port A and the port B, so that the hydraulic shaft is controlled to move. Motion control of a machine tool and the characteristics of the high-frequency-response servo proportional valve can be well combined, the response time of the proportional valve for generating the correct opening degree is greatly shortened, and hydraulic shaft position control is more accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of high-frequency response valves, and in particular to a full-closed-loop control method of a high-frequency response valve. Background Art

[0002] The electro-hydraulic servo proportional valve is a common hydraulic component that controls the hydraulic axis of CNC machine tools. The high-frequency response servo proportional valve uses dual coils to obtain electricity and uses the potential difference to drive the valve core to move. Compared with the low-frequency response valve, it has the advantages of high response speed and high control accuracy. However, the existing CNC system lacks the ability to calculate the current of the dual coils and can only calculate the output of the single coil, resulting in a long response time for the proportional valve. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a fully closed-loop control method for the valve core position of a high-frequency response proportional valve. An independent PID algorithm is used for the valve core position to directly calculate the real-time current of the proportional valve A and B ports, and drive the double coil to operate, thereby making up for the defect that the existing CNC system lacks the ability to calculate the double coil current.

[0004] In view of the shortcomings of the prior art, the present invention solves the technical problems by adopting a technical solution: a full closed-loop control method for a high-frequency response valve, comprising the following steps:

[0005] Step 1: Establish the motion controller, grating ruler / magnetic ruler and high-frequency response servo proportional valve. The motion controller receives the PID parameters of the host computer. The motion controller and the grating ruler / magnetic ruler communicate through the encoder cable. The high-frequency response servo proportional valve includes port A and port B. The high-frequency response servo proportional valve and the motion controller are connected through the valve control cable. The grating ruler / magnetic ruler feeds back the position information of the hydraulic axis to the motion controller.

[0006] Step 2: The motion controller receives the feedback position of the grating scale / magnetic scale and calculates the speed command of the hydraulic axis, which specifically includes the following steps:

[0007] Step S2-1: The motion controller receives the real-time position value of the hydraulic axis fed back by the grating ruler / magnetic ruler;

[0008] Step S2-2: The motion controller calculates the motion planning curve of the hydraulic axis according to the current position, target position, acceleration and deceleration, and maximum speed set by itself;

[0009] Step S2-3: The motion controller calculates the following error based on the motion planning curve and the actual position fed back by the grating ruler / magnetic ruler;

[0010] Step S2-4: The motion controller calculates the speed command according to the following error value and PID parameters;

[0011] Step 3: The motion controller performs closed-loop control of the valve core position according to the speed command and the valve core position fed back by the high-frequency response servo proportional valve, calculates the real-time current of the A and B ports of the high-frequency response servo proportional valve, and outputs the current to the high-frequency response servo proportional valve through the valve control cable to execute precise control of the hydraulic axis position.

[0012] Preferably, the motion controller is provided with an FPGA chip, a DSP chip, a shared memory and a peripheral interface circuit. The DSP chip executes motion control planning and calculation, the DSP chip is connected to the shared memory, the shared memory is connected to the FPGA chip, and the FPGA chip is connected to the peripheral interface circuit; the peripheral interface circuit includes a digital IO port, an encoder interface, a valve interface and an analog IO port. The digital IO port is connected to an external switching signal, the encoder interface is used to transmit the position data obtained by the grating scale / magnetic scale, the valve interface is used to drive a high-frequency response servo proportional valve, and the valve core position information of the high-frequency response servo proportional valve is obtained through the voltage-type input port in the analog IO; the FPGA chip is used to process the electrical signal obtained by the peripheral interface circuit.

[0013] Preferably, when executing step 3, the following steps are specifically included:

[0014] Step S3-1: The FPGA chip obtains the valve core position feedback signal of the high-frequency response servo proportional valve through the analog IO port;

[0015] Step S3-2: The FPGA chip processes the electrical signal obtained in step S3-1 and converts it into position information and stores it in the shared memory;

[0016] Step S3-3: The DSP chip retrieves the position information from the shared memory, and calculates it according to the fully closed-loop PID algorithm of the valve core position of the high-frequency response servo proportional valve. The PID algorithm is executed by the valve core PID controller A and the valve core PID controller B respectively. The valve core PID controller A and the valve core PID controller B obtain the real-time current instructions of the A port and the B port of the high-frequency response servo proportional valve and give them to the electromagnet on the corresponding side;

[0017] Step S3-4: the DSP chip stores the current instruction in the shared memory;

[0018] Step S3-5: The FPGA chip retrieves the current instruction from the shared memory and sends a control signal to the peripheral interface circuit. The peripheral interface circuit drives the servo proportional valve to operate through the valve interface according to the received control signal.

[0019] The beneficial effects of the present invention are as follows: The full-closed-loop control method of a high-frequency response valve described in the present invention solves the problem that the existing numerical control system lacks the ability to calculate dual-coil current and can only calculate single-coil output, resulting in a long proportional valve response time, and the use of analog output converted into current through an amplifier card causes cost increases. When the present invention is combined with a high-frequency response servo proportional valve, the full-closed-loop algorithm greatly shortens the valve core action response time compared to the previous semi-closed-loop control, and the control accuracy is greatly improved, thereby improving the product's independent technical content and market competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a system connection diagram involved in the present invention;

[0021] Figure 2 is a flow chart involved in step 2 of the present invention;

[0022] Figure 3 is a flow chart involved in step 3 of the present invention;

[0023] Figure 4 This is a flow chart of the valve core algorithm involved in the steps of the present invention;

[0024] Figure 5 2 is an electrical characteristic diagram of the valve core of the present invention. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments of the present invention are provided for the purpose of illustration and description, and are not intended to be exhaustive or to limit the present invention to the disclosed forms. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are selected and described in order to better illustrate the principles and practical applications of the present invention, and to enable those of ordinary skill in the art to understand the present invention and thereby design various embodiments with various modifications suitable for specific uses.

[0026] Depend on Figure 1-Figure 3The described method for fully closed-loop control of a high-frequency response valve includes a motion controller, a grating scale / magnetic scale and a high-frequency response servo proportional valve. The motion controller receives the PID parameters of the host computer. The motion controller is provided with an FPGA chip, a DSP chip, a shared memory and a peripheral interface circuit. The DSP chip performs motion control planning and calculations. The DSP chip is connected to the shared memory, the shared memory is connected to the FPGA chip, and the FPGA chip is connected to the peripheral interface circuit; the peripheral interface circuit includes a digital IO port, an encoder interface, a valve interface and an analog IO port. The digital IO port is connected to an external switch signal. The encoder interface is used to transmit the position data obtained by the grating scale / magnetic scale. The valve interface is used to drive the high-frequency response servo proportional valve. The valve core position information of the high-frequency response servo proportional valve is obtained through the voltage input port in the analog IO; the FPGA chip is used to process the electrical signal obtained by the peripheral interface circuit. The method for fully closed-loop control of a high-frequency response valve includes the following steps:

[0027] Step 1: Establish the motion controller, grating ruler / magnetic ruler and high-frequency response servo proportional valve. The motion controller and grating ruler / magnetic ruler communicate through the encoder cable. The high-frequency response servo proportional valve includes port A and port B. The motion controller and the high-frequency response servo proportional valve are connected through the valve control cable. The grating ruler / magnetic ruler feeds back the position information of the hydraulic axis to the motion controller.

[0028] Step 2: The motion controller calculates the speed command of the hydraulic axis according to the feedback position of the grating scale / magnetic scale, which specifically includes the following steps:

[0029] Step S2-1: The motion controller receives the real-time position value of the hydraulic axis fed back by the grating ruler / magnetic ruler;

[0030] Step S2-2: The motion controller calculates the motion planning curve of the hydraulic axis according to the current position, target position, acceleration and deceleration, and maximum speed set by itself;

[0031] Step S2-3: The motion controller calculates the following error based on the motion planning curve and the actual position fed back by the grating ruler / magnetic ruler;

[0032] Step S2-4: The motion controller calculates the speed command according to the following error value and PID parameters;

[0033] The motion controller processes the feedback position of the grating scale / magnetic scale as follows:

[0034] The feedback position of the grating ruler / magnetic ruler read by the motion controller in each cycle is ActPos, and the planned position is SetPos, then the following error Err of this cycle = SetPos-ActPos;

[0035] Integration calculation: When the number of cycles is less than or equal to the integration cycle KI_NUM, the integration amount ErrAdd = ErrAdd + Err; when the number of cycles is greater than the integration cycle KI_NUM, the integration amount ErrAdd = ErrAdd + Err – Err of the current earliest cycle; this ensures that ErrAdd is the sum of Err of the previous KI_NUM cycles;

[0036] Speed ​​command calculation: OutPut = Err*Kp + ErrAdd*Ki;

[0037] Step 3: The motion controller performs closed-loop control of the valve core position according to the speed command and the valve core position fed back by the high-frequency response servo proportional valve, calculates the real-time current of the A and B ports of the high-frequency response servo proportional valve, and outputs the current to the high-frequency response servo proportional valve through the valve control cable to execute precise control of the hydraulic axis position;

[0038] Processing of proportional valve spool feedback position;

[0039] According to the calculated speed command and the received valve core position signal, the valve core position closed-loop control operation is performed;

[0040] The calculation results are output to the A and B ports of the proportional valve at the same time to perform precise axis position control.

[0041] When executing step 3, the specific steps include:

[0042] Step S3-1: The FPGA chip obtains the valve core position feedback signal of the high-frequency response servo proportional valve through the analog IO port;

[0043] Step S3-2: The FPGA chip processes the electrical signal obtained in step S3-1 and converts it into position information and stores it in the shared memory;

[0044] Step S3-3: The DSP chip retrieves the position information from the shared memory and calculates according to the fully closed-loop PID algorithm of the high-frequency response servo proportional valve spool position. The PID algorithm is executed by the spool PID controller A and the spool PID controller B respectively. The spool PID controller A and the spool PID controller B obtain the real-time current instructions of the A port and the B port of the high-frequency response servo proportional valve and give them to the electromagnet on the corresponding side. The function model of the fully closed-loop PID algorithm is as follows:

[0045] int PIH_Control(int OutPut,int LVDT,int p_fak,int i_fak,int min_a,intmin_b,int max_a,int max_b,int center,int red_a,int red_b)

[0046] Among them, OutPut is the calculated speed command; LVDT is the received valve core position feedback; p_fak is the valve core closed-loop control Kp; i_fak is the valve core closed-loop control Ki; min_a is the positive dead zone of the proportional valve; min_b is the negative dead zone of the proportional valve; max_a is the maximum voltage of the proportional valve; max_b is the minimum voltage of the proportional valve; center is the center voltage of the proportional valve; red_a is the scaling ratio of port A, the function calculation value * red_a / 1000 = the actual output of port A; red_b is the scaling ratio of port B, the function calculation value * red_b / 1000 = the actual output of port B; Figure 4 As shown, the maximum voltage of the proportional valve, the positive dead zone of the proportional valve, the mid-position voltage of the proportional valve, the negative dead zone of the proportional valve, the minimum voltage of the proportional valve, and the valve core position signal constitute the valve core position data. The valve core position data is combined with the A port scaling ratio, the speed command calculated in step 2 (also called the analog speed command), and the B port scaling ratio to be respectively given to the valve core PID controller A and the valve core PID controller B. The current output by the valve core PID controller A is used as the driving current of the electromagnet on the A port side, and the current output by the valve core PID controller B is used as the driving current of the electromagnet on the B port side, thereby realizing the control of the oil output of the A port and the B port, and adjusting the valve core position;

[0047] Step S3-4: the DSP chip stores the current instruction in the shared memory;

[0048] Step S3-5: The FPGA chip retrieves the current instruction from the shared memory and sends a control signal to the peripheral interface circuit. The peripheral interface circuit drives the servo proportional valve according to the control signal through the valve interface.

[0049] The high-frequency response valve involved in the full-closed-loop control method of the high-frequency response valve of the present invention is a double-electromagnet current distribution, which relies on the potential difference of the electromagnets on both sides of the oil outlet A and B to drive the valve core position adjustment, realize the real-time dynamic adjustment of the valve core position, and is a physical drive; the electrical characteristics of the valve core are as follows Figure 5 As shown, when the valve core feedback voltage is 3V-6.75V, port A is open and port B is closed, and the smaller the voltage, the larger the opening of port A; when the feedback voltage is 8.25V-12V, port A is closed and port B is open, and the larger the voltage, the larger the opening of port B; the 6.75V-8.25V in the middle that is shielded is called the dead zone. When the voltage falls in the dead zone, both ports are shielded and no oil is discharged; the present invention solves the problem that the existing numerical control system lacks the ability to calculate the current of the dual coil, and can only calculate the output of the single coil, resulting in a long response time of the proportional valve, or uses analog output, which is converted into current by the amplifier card, resulting in an increase in cost. The advantage of the present invention is that it uses an independent PID algorithm for the valve core position, directly calculates the real-time current of the proportional valve port A and port B, and drives the dual electromagnets to act, so as to achieve fast response and precise control.

Claims

1. A fully closed-loop control method for a high-frequency response valve, characterized in that: The following steps are included: Step 1: Establish the motion controller, grating ruler / magnetic ruler and high-frequency response servo proportional valve. The motion controller receives the PID parameters of the host computer. The motion controller and the grating ruler / magnetic ruler communicate through the encoder cable. The high-frequency response servo proportional valve includes port A and port B. The high-frequency response servo proportional valve and the motion controller are connected through the valve control cable. The grating ruler / magnetic ruler feeds back the position information of the hydraulic axis to the motion controller. Step 2: The motion controller receives the feedback position of the grating scale / magnetic scale and calculates the speed command of the hydraulic axis, which specifically includes the following steps: Step S2-1: The motion controller receives the real-time position value of the hydraulic axis fed back by the grating ruler / magnetic ruler; Step S2-2: The motion controller calculates the motion planning curve of the hydraulic axis according to the current position, target position, acceleration and deceleration, and maximum speed set by itself; Step S2-3: The motion controller calculates the following error based on the motion planning curve and the actual position fed back by the grating ruler / magnetic ruler; Step S2-4: The motion controller calculates the speed command according to the following error value and PID parameters; Step 3: The motion controller performs closed-loop control of the valve core position according to the speed command and the valve core position fed back by the high-frequency response servo proportional valve, calculates the real-time current of the A and B ports of the high-frequency response servo proportional valve, and outputs the current to the high-frequency response servo proportional valve through the valve control cable to execute precise control of the hydraulic axis position.

2. A fully closed-loop control method for a high-frequency response valve as claimed in claim 1, characterized in that: The motion controller is provided with an FPGA chip, a DSP chip, a shared memory and a peripheral interface circuit. The DSP chip executes motion control planning and calculation. The DSP chip is connected to the shared memory, the shared memory is connected to the FPGA chip, and the FPGA chip is connected to the peripheral interface circuit; the peripheral interface circuit includes a digital IO port, an encoder interface, a valve interface and an analog IO port. The digital IO port is connected to an external switching signal. The encoder interface is used to transmit position data obtained by a grating ruler / magnetic ruler. The valve interface is used to drive a high-frequency response servo proportional valve. The valve core position information of the high-frequency response servo proportional valve is obtained through a voltage-type input port in the analog IO; the FPGA chip is used to process the electrical signal obtained by the peripheral interface circuit.

3. A fully closed-loop control method for a high-frequency response valve as claimed in claim 2, characterized in that: When executing step 3, the specific steps include: Step S3-1: The FPGA chip obtains the valve core position feedback signal of the high-frequency response servo proportional valve through the analog IO port; Step S3-2: The FPGA chip processes the electrical signal obtained in step S3-1 and converts it into position information and stores it in the shared memory; Step S3-3: The DSP chip retrieves the position information from the shared memory, and calculates according to the high-frequency response servo proportional valve spool position full closed-loop algorithm. The PID algorithm is executed by the spool PID controller A and the spool PID controller B respectively. The spool PID controller A and the spool PID controller B obtain the real-time current instructions of the high-frequency response servo proportional valve A port and B port and give them to the electromagnet on the corresponding side. Step S3-4: the DSP chip stores the current instruction in the shared memory; Step S3-5: The FPGA chip retrieves the current instruction from the shared memory and sends a control signal to the peripheral interface circuit. The peripheral interface circuit drives the servo proportional valve to operate through the valve interface according to the received control signal.

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