CN115111227B - Load port independent decoupling control system based on speed and pressure feedback - Google Patents
Load port independent decoupling control system based on speed and pressure feedback Download PDFInfo
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- CN115111227B CN115111227B CN202210766853.0A CN202210766853A CN115111227B CN 115111227 B CN115111227 B CN 115111227B CN 202210766853 A CN202210766853 A CN 202210766853A CN 115111227 B CN115111227 B CN 115111227B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
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- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
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Abstract
The invention provides a load port independent decoupling control system based on speed and pressure feedback, which comprises a hydraulic actuator, two load port independent control valves, two pressure sensors, a speed sensor and a controller, wherein working oil ports corresponding to the two load port independent control valves are respectively connected with two cavities of the hydraulic actuator, and the two pressure sensors respectively send detected pressure information of the two cavities to the controller; the speed sensor sends the detected running speed of the hydraulic actuator to the controller; the controller comprises a speed control loop, a pressure control loop and a speed feedback decoupling control unit, wherein the speed feedback decoupling control unit provides a first decoupling compensation quantity and a second decoupling compensation quantity for the speed control loop and the pressure control loop respectively so as to eliminate coupling interference between the speed control loop and the pressure control loop. The invention can not only reduce the energy consumption of the hydraulic actuator, but also has simple control logic, reduces the mutual interference of multiple variables and improves the dynamic characteristic.
Description
Technical Field
The invention belongs to the field of control of hydraulic actuators, and particularly relates to a load port independent decoupling control system based on speed and pressure feedback.
Background
When the load port independent control valve with the inlet and outlet valve cores capable of being independently adjusted controls the hydraulic actuator to move, the energy consumption of the hydraulic actuator can be reduced by reducing the pressure of the back cavity and regenerating and recycling energy. For this reason, the control process needs to adopt a speed and pressure composite control mode and the like. However, the pressure, the speed and the like of the two cavities are interfered by the related coupling of the internal characteristics of the system, and the existing speed and pressure composite control logic is relatively complex. If the speed and the pressure are respectively controlled by independent control systems, although the control logic is simpler, and the speed and the pressure are superficially controlled respectively, in practice, in a speed and pressure independent closed-loop control loop, two control loops are mutually associated and coupled through the pressures of two cavities in a hydraulic actuator, and the change of one control quantity in the speed and the pressure can greatly influence the other control quantity, so that the speed and pressure independent control system can hardly achieve satisfactory dynamic control performance, and the problems of severe oscillation and impact are caused.
Disclosure of Invention
The invention provides a load port independent decoupling control system based on speed and pressure feedback, which aims to solve the problems that in the control process of a hydraulic actuator, a speed and pressure composite control system is adopted at present, energy consumption can be reduced, but the control logic is relatively complex, and the adoption of the speed and pressure independent control system is simple, but the vibration impact is severe and the like due to coupling interference between a speed control loop and a pressure control loop and poor dynamic control performance.
According to a first aspect of the embodiments of the present invention, a load port independent decoupling control system based on speed and pressure feedback is provided, including a hydraulic actuator, two load port independent control valves, two pressure sensors, a speed sensor and a controller, where working oil ports corresponding to the two load port independent control valves are respectively connected to two chambers of the hydraulic actuator, and the two pressure sensors respectively send detected pressure information of the two chambers to the controller; the speed sensor sends the detected running speed of the hydraulic actuator to the controller; the controller comprises a speed control loop, a pressure control loop and a feedforward decoupling control unit, wherein the feedforward decoupling control unit provides a first feedforward compensation quantity and a second feedforward compensation quantity for the speed control loop and the pressure control loop respectively so as to eliminate coupling interference between the speed control loop and the pressure control loop;
in actual control, the speed control loop obtains a first initial control signal according to a target speed and a detected running speed, adds the first initial control signal to the first feedforward compensation quantity to obtain a first control signal of a first load port independent control valve, and controls the opening of the first load port independent control valve according to the first control signal, so that the flow entering the hydraulic actuator is controlled, and the speed tracking regulation is realized;
and the pressure control loop acquires a second initial control signal according to the target pressure and the detected pressure of the second chamber, adds the second initial control signal to the second feedforward compensation quantity to acquire a second control signal of the second load port independent control valve, and performs pressure tracking adjustment based on the detected pressure of the second chamber.
In an alternative implementation manner, the feedforward decoupling control unit calculates the first feedforward compensation quantity u according to the following formula according to the detected running speed of the hydraulic actuator f1 ：
Wherein v is cy Indicating the detected speed of operation, q (x) v1 ,Δp 1 ) Denotes the flow of the first chamber, A a The working area of the first chamber is shown,
ω v1 representing the natural frequency, s, of the first load port independent control valve 1 Representing a transfer function after Laplace transform of a first differential link;
the feedforward decoupling control unit calculates the second feedforward compensation quantity u according to the following formula according to the detected running speed of the hydraulic actuator f2 ：
Wherein v is cy Indicating the detected speed of operation, q (x) v2 ,Δp 2 ) Indicating the flow of the second chamber, A b The working area of the second chamber is shown,
ω v2 representing the natural frequency, s, of the second load port independent control valve 2 Representing the transfer function after the second differential-element laplace transform.
In another optional implementation manner, the control unit further includes a two-cavity dynamic pressure feedback control unit, where the two-cavity dynamic pressure feedback control unit provides a first negative feedback adjustment amount and a second negative feedback adjustment amount to the speed control loop and the pressure control loop, respectively, so as to improve dynamic stability of the speed control loop and the pressure control loop;
in actual control, the speed control loop adds the first initial control signal, the first feedforward compensation quantity and the first negative feedback adjustment quantity to obtain a first control signal of the first load port independent control valve; and the pressure control loop adds the second initial control signal, the second feedforward compensation quantity and the second negative feedback adjustment quantity to obtain a second control signal of the second load port independent control valve.
In another optional implementation manner, the two-cavity dynamic pressure feedback control unit calculates the first negative feedback adjustment amount u according to the following formula p1 ：
Wherein p is a Indicating the detected pressure of the first chamber, k 1 A first example of a procedure is shown,
representing the combination of the first order inertia element and the differential element, τ c1 Represents the first inertia element time constant, s 1 Representing a transfer function after Laplace transform of a first differential link;
the two-cavity dynamic pressure feedback control unit calculates the second negative feedback regulating quantity u according to the following formula p2 ：
Wherein p is b Indicating the detected pressure of the second chamber, k 2 A second proportional element is shown and indicated,
representing the combination of the second inertial element with the differential element, tau c2 Representing a second inertial element time constant; s is 2 Representing the transfer function after the second differential-element laplace transform.
In another optional implementation manner, the first-order inertia element and the second-order inertia element are configured to adjust magnitudes of the first control signal and the second control signal, the first proportional element and the second proportional element are configured to adjust response speeds of the first load port independent control valve and the second load port independent control valve, and the first differential element and the second differential element are configured to obtain pressure oscillation characteristics of the first chamber and the second chamber, respectively.
In another optional implementation manner, the pressure information of the two cavities detected by the two pressure sensors is the pressure at the working oil port of the first load port independent control valve and the pressure at the working oil port of the second load port independent control valve; the oil inlets of the first load port independent control valve and the second load port independent control valve are connected, and a third pressure sensor is further arranged at the connection node and used for detecting the pressure at the oil inlets of the first load port independent control valve and the second load port independent control valve;
flow rate q (x) of the first chamber v1 ,Δp 1 ) The preparation method comprises the following steps:
determining the valve core displacement x of the first load port independent control valve according to the first initial control signal v1 (ii) a Determining the pressure difference delta p between two ends of the first load port independent control valve according to the pressure information between two ends of the valve port of the first load port independent control valve 1 The pressure information at the two ends of the valve port of the first load port independent control valve is the pressure at the two ends of the working oil port and the oil inlet;
the valve core displacement x of the first load port independent control valve v1 And the pressure difference deltap between the two ends of the first load port independent control valve 1 In connection with valvesCalculating the flow q of the first cavity corresponding to the first load port independent control valve by using a flow characteristic model of core displacement and valve port differential pressure a ：q a ＝q(x v1 ,Δp 1 )；
Flow rate q (x) of the second chamber v2 ,Δp 2 ) The preparation method comprises the following steps:
determining the valve core displacement x of the second load port independent control valve according to the second initial control signal v2 (ii) a Determining the pressure difference delta p between the two ends of the second load port independent control valve according to the pressure information between the two ends of the valve port of the second load port independent control valve 2 The pressure information at the two ends of the valve port of the second load port independent control valve is the pressure at the two ends of the working oil port and the oil inlet;
independently controlling the valve core displacement x of the valve according to the second load port v2 And the pressure difference deltap between the two ends of the second load port independent control valve 2 And calculating the flow q of the second cavity corresponding to the second load port independent control valve by combining a flow characteristic model about valve core displacement and valve port differential pressure b ：q b ＝q(x v2 ,Δp 2 )。
In another alternative implementation, the obtaining, by the speed control loop, the first initial control signal according to the target speed and the detected operating speed includes: comparing the target speed with the detected running speed, calculating a speed difference value, and inputting the speed difference value into a PID speed regulator to obtain the first initial control signal;
the pressure control circuit obtaining a second initial control signal based on the target pressure and the sensed pressure of the second chamber comprises: and comparing the target pressure with the detected pressure of the second cavity, calculating a pressure difference value, and inputting the pressure difference value into a PID speed regulator to obtain the second initial control signal.
In another optional implementation manner, when the hydraulic actuator extends out, the speed control circuit compares a target speed with a detected running speed, calculates a speed difference value, and inputs the speed difference value to a PID speed regulator to obtain the first initial control signal; the pressure control loop compares a target pressure with the detected pressure of the second cavity, calculates a pressure difference value, inputs the pressure difference value into a PID speed regulator to obtain a second initial control signal, and sets the target pressure to be as low as 2bar so as to reduce outlet throttling loss;
when the hydraulic actuator retracts, the speed control loop compares a target speed with a detected running speed, calculates a speed difference value, and inputs the speed difference value into a PID speed regulator to obtain a second initial control signal; and the pressure control loop compares the target pressure with the detected pressure of the second cavity, calculates a pressure difference value, inputs the pressure difference value into a PID speed regulator, and obtains the first initial control signal, wherein the target pressure is set to be as low as 2bar so as to reduce the outlet throttling loss.
In another alternative implementation, the first feedforward compensation amount and the second feedforward compensation amount are derived according to the following steps: establishing a composite physical model of the speed control loop and the pressure control loop;
in the composite physical model, theoretically, the pressure control circuit obtains the second initial control signal according to a target pressure and the detected pressure of the second cavity; calculating the flow of the second cavity according to the second initial control signal; calculating the pressure of the second cavity according to the flow of the second cavity, the detected running speed and the working area of the second cavity, and performing pressure tracking adjustment based on the detected pressure of the second cavity;
the speed control loop obtains the first initial control signal according to a target speed and the detected running speed; calculating the flow of the first cavity according to the first control signal; calculating the pressure of the first cavity according to the flow of the first cavity, the detected running speed and the working area of the first cavity, calculating the running speed according to the calculated pressures of the first cavity and the second cavity, and performing speed tracking adjustment based on the calculated running speed;
and analyzing that the interference of the first cavity on the second cavity is related to the operation speed and the working area of the second cavity according to a calculation formula of the pressure of the second cavity and the operation speed, and the interference of the second cavity on the first cavity is related to the operation speed and the working area of the first cavity.
In another alternative implementation, the pressure control circuit calculates the pressure p of the second chamber from the flow rate of the second chamber, the detected operating speed and the working area of the second chamber according to the following formula b ：
Wherein
V b Denotes the volume of the second chamber, beta e2 Denotes the modulus of elasticity, q, of the oil in the second chamber b Indicating the flow of the second chamber, A b Representing the working area of the second chamber, v cy Indicating a detected operating speed;
the speed control loop calculates the pressure p of the first cavity according to the following formula according to the flow of the first cavity, the detected running speed and the working area of the first cavity a ：
Wherein
V a Denotes the volume of the first chamber volume, beta e1 Expressing the modulus of elasticity, q, of the oil in the first chamber a Denotes the flow of the first chamber, A a Denotes the working area of the first chamber, v cy Indicating the detected operating speed;
the speed control loop calculates the pressure p of the first cavity a And a second chamberPressure p b The running speed v is calculated according to the following formula cy ：
Where m denotes the equivalent load mass of the hydraulic actuator, p a Denotes the pressure of the first chamber, A a Denotes the working area of the first chamber, p b Denotes the pressure of the second chamber, A b Denotes the working area of the second chamber, F L Representing the load force of the hydraulic actuator;
and analyzing and determining the first feedforward compensation amount and the second feedforward compensation amount according to the formula.
The beneficial effects of the invention are:
1. the speed and pressure control system comprising the speed control loop and the pressure control loop has the characteristics of a composite control system and the characteristics of an independent control system, and not only can reduce the pressure of a back cavity and the pressure loss of an outlet and reduce the energy consumption of a hydraulic actuator, but also has simple control logic; the invention introduces a feedforward decoupling control unit, can eliminate the coupling interference between a speed control loop and a pressure control loop, can improve the poor dynamic control performance and avoid severe vibration impact;
2. the invention introduces a two-cavity dynamic pressure feedback control unit, obtains a pressure differential signal representing the dynamic stability of the system, and adjusts the control signal through a first-order inertia link and a proportion link, thereby improving the dynamic stability of two independent control loops of speed and pressure while improving the quick response.
Drawings
FIG. 1 is a schematic structural diagram of an embodiment of a load port independent decoupling control system based on speed and pressure feedback;
FIG. 2 is a schematic diagram of a composite physical model of a speed control loop and a pressure control loop prior to the introduction of a feed forward decoupling control unit in accordance with the present invention;
FIG. 3 is a control logic diagram of one embodiment of the present invention incorporating a feed forward decoupling control unit;
FIG. 4 is an equivalent physical model of the invention after a feedforward decoupling control unit is introduced and coupling characteristics are eliminated;
FIG. 5 is a complete control logic diagram of the system after a feedforward decoupling control unit and a two-cavity dynamic pressure feedback control unit are introduced.
Detailed Description
In order to make the technical solutions in the embodiments of the present invention better understood and make the above objects, features and advantages of the embodiments of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention are further described in detail below with reference to the accompanying drawings.
In the description of the present invention, unless otherwise specified and limited, it is to be noted that the term "connected" is to be interpreted broadly, and may be, for example, a mechanical connection or an electrical connection, or a communication between two elements, or may be a direct connection or an indirect connection through an intermediate medium, and a specific meaning of the term may be understood by those skilled in the art according to specific situations.
Referring to fig. 1, it is a schematic structural diagram of an embodiment of the load port independent decoupling control system based on speed and pressure feedback according to the present invention. The system can comprise a hydraulic actuator 1, two load port independent control valves 31 and 32, two pressure sensors 2 and 4, a speed sensor 5 and a controller 6, wherein working oil ports A and B corresponding to the two load port independent control valves 31 and 32 are respectively connected with two cavities (the two cavities can be a rodless cavity and a rod cavity) of the hydraulic actuator 1, and the two pressure sensors 2 and 4 respectively send detected pressure information of the two cavities to the controller 6; the speed sensor 5 sends the detected operating speed of the hydraulic actuator 1 to the controller 6. The controller comprises a speed control loop, a pressure control loop and a feedforward decoupling control unit, wherein the feedforward decoupling control unit provides a first feedforward compensation amount and a second feedforward compensation amount for the speed control loop and the pressure control loop respectively so as to eliminate coupling interference between the speed control loop and the pressure control loop.
In this embodiment, both the two load port independent control valves 31 and 32 may be three-position three-way electric proportional directional valves, the pressure sensors 2 and 4 are respectively disposed at the working oil ports a and B corresponding to the load port independent control valves 31 and 32, and the working oil ports a and B corresponding to the load port independent control valves 31 and 32 are respectively connected to two chambers of the hydraulic actuator 1, so that the pressures of the two chambers detected by the pressure sensors 2 and 4 are the pressures at the working oil ports a and B. The oil inlets C and D of the two load port independent control valves 31 and 32 are connected, and the connecting node of the two load port independent control valves is connected with the oil outlet of the hydraulic pump 7 and is connected with the oil tank through an electric proportional overflow valve 8 (or a manual overflow valve 8). The two load port independent control valves 31 and 32 are connected to oil return ports E and F, and their connection nodes are connected to a tank, wherein the hydraulic actuator may be a hydraulic cylinder.
Because the pressure and the speed of the two cavities are mutually coupled and interfered by the internal characteristics of the system, the control logic of the existing speed and pressure composite control system is complex, if the speed and the pressure are respectively independent control systems, although the control logic is simpler, the two control loops are mutually interfered, so the control logic of the speed and pressure composite control system is simplified, as shown in figure 2, the speed and pressure composite control system is a speed and pressure composite control system before a feedforward decoupling control unit is introduced, 6.1 in figure 2 represents a speed control loop, and 6.2 represents a pressure control loop. Because the coupling interference related to the speed of the hydraulic actuator exists between the first cavity pressure and the second cavity pressure, and the speed control loop and the pressure control loop are respectively compensated in order to analyze the mutual interference amount between the first cavity pressure and the second cavity pressure. Specifically, in the composite physical model, theoretically, the pressure control circuit obtains the second initial control signal according to a target pressure and a detected pressure of the second cavity; calculating the flow of the second cavity according to the second initial control signal; calculating the pressure of the second cavity according to the flow of the second cavity, the detected running speed and the working area of the second cavity, and performing pressure tracking adjustment on the basis of the detected pressure of the second cavity; the speed control loop obtains the first initial control signal according to a target speed and the detected running speed; calculating the flow of the first cavity according to the first control signal; calculating the pressure of the first cavity according to the flow of the first cavity, the detected running speed and the working area of the first cavity, calculating the running speed according to the calculated pressures of the first cavity and the second cavity, and performing speed tracking adjustment based on the calculated running speed; and analyzing that the interference of the first cavity to the second cavity is related to the operating speed and the working area of the second cavity according to a calculation formula of the pressure of the second cavity and the operating speed, and the interference of the second cavity to the first cavity is related to the operating speed and the working area of the first cavity.
The pressure control circuit calculates the pressure p of the second chamber according to the following formula according to the flow of the second chamber, the detected running speed and the working area of the second chamber b ：
Wherein
V b Denotes the volume of the second chamber, beta e2 Expressing the modulus of elasticity, q, of the oil in the second chamber b Indicating the flow of the second chamber, A b Representing the working area of the second chamber, v cy Indicating a detected operating speed;
the speed control loop calculates the pressure p of the first cavity according to the following formula according to the flow of the first cavity, the detected running speed and the working area of the first cavity a ：
Wherein
V a Denotes the first chamber volume, beta e1 Expressing the modulus of elasticity, q, of the oil in the first chamber a Denotes the flow of the first chamber, A a Denotes the working area of the first chamber, v cy Indicating the detected operating speed;
the speed control loop calculates the pressure p of the first cavity a And pressure p of the second chamber b The running speed v is calculated according to the following formula cy ：
Where m denotes the equivalent load mass of the hydraulic actuator, p a Denotes the pressure of the first chamber, A a Denotes the working area of the first chamber, p b Denotes the pressure of the second chamber, A b Denotes the working area of the second chamber, F L Representing the load force of the hydraulic actuator. The first and second feedforward compensation amounts may be analytically determined according to the above equations.
After the first feedforward compensation amount and the second feedforward compensation amount are obtained, a feedforward decoupling control unit which respectively provides the first feedforward compensation amount and the second feedforward compensation amount to a speed control loop and a pressure control loop can be introduced, the control logic of the composite control system after the feedforward decoupling control unit is introduced is shown in fig. 3, an equivalent physical model diagram of the system elimination coupling characteristic after the feedforward decoupling control unit of fig. 3 is adopted is shown in fig. 4, and it can be seen from fig. 4 that no associated parameter exists between the speed control loop and the pressure control loop, and the coupling interference is eliminated. Therefore, in actual control, the speed control loop obtains a first initial control signal according to a target speed and a detected running speed, adds the first initial control signal to the first feedforward compensation quantity to obtain a first control signal of the first load port independent control valve, and controls the opening of the first load port independent control valve according to the first control signal, so that the flow entering the hydraulic actuator is controlled, and the speed tracking adjustment is realized; and the pressure control loop obtains a second initial control signal according to the target pressure and the detected pressure of the second chamber, adds the second initial control signal to the second feedforward compensation quantity to obtain a second control signal of the second load port independent control valve, and performs pressure tracking adjustment based on the detected pressure of the second chamber.
The feedforward decoupling control unit calculates the first feedforward compensation amount u according to the following formula according to the detected running speed of the hydraulic actuator f1 ：
Wherein v is cy Indicating the detected running speed, q (x) v1 ,Δp 1 ) Denotes the flow of the first chamber, A a The working area of the first chamber is shown,
ω v1 representing the natural frequency, s, of the first load port independent control valve 1 Representing a transfer function after a first differential element Laplace transform;
the feedforward decoupling control unit calculates the second feedforward compensation quantity u according to the following formula according to the detected running speed of the hydraulic actuator f2 ：
Wherein v is cy Indicating the detected running speed, q (x) v2 ,Δp 2 ) Indicating the flow of the second chamber, A b The working area of the second chamber is shown,
ω v2 representing the natural frequency, s, of the second load port independent control valve 2 Representing the transfer function after the second differential-element laplace transform.
The speed control loop obtaining a first initial control signal according to the target speed and the detected running speed comprises: comparing the target speed with the detected running speed, calculating a speed difference value, and inputting the speed difference value into a PID speed regulator to obtain the first initial control signal; the pressure control circuit obtaining a second initial control signal based on the target pressure and the sensed pressure of the second chamber comprises: and comparing the target pressure with the detected pressure of the second cavity, calculating a pressure difference value, and inputting the pressure difference value into a PID speed regulator to obtain the second initial control signal.
When the hydraulic actuator extends out, the speed control loop compares a target speed with a detected running speed, calculates a speed difference value, and inputs the speed difference value into a PID speed regulator to obtain the first initial control signal; the pressure control loop compares a target pressure with the detected pressure of the second cavity, calculates a pressure difference value, inputs the pressure difference value into a PID speed regulator to obtain a second initial control signal, and the target pressure can be set to be as low as 2bar so as to reduce outlet throttling loss; when the hydraulic actuator retracts, the speed control circuit compares a target speed with a detected running speed, calculates a speed difference value, inputs the speed difference value into a PID speed regulator and obtains a second initial control signal; and the pressure control loop compares a target pressure with the detected pressure of the second cavity, calculates a pressure difference value, inputs the pressure difference value into the PID speed regulator to obtain the first initial control signal, and the target pressure can be set to be as low as 2bar so as to reduce the outlet throttling loss.
In this embodiment, one of the two pressure sensors will send pressure information to the pressure control circuit after detecting the pressure in the second chamber, and the speed sensor will operate after detecting the operating speedThe line speeds are sent to a speed control circuit and a pressure control circuit, respectively. When the load control valve is a three-position three-way electric proportional direction valve, the controller can be connected with proportional electromagnets of the two three-position three-way electric proportional direction valves and is used for adjusting the opening degree of a valve port of the electric proportional adjusting valve. The pressure information of the two cavities detected by the two pressure sensors 2 and 4 is the pressure at the working oil port a of the first load port independent control valve 31 and the pressure at the working oil port B of the second load port independent control valve 32; oil inlets C and D of the first load port independent control valve 31 and the second load port independent control valve 32 are connected, and a third pressure sensor 9 is further arranged at the connection node and used for detecting the pressure at the oil inlets of the first load port independent control valve 31 and the second load port independent control valve 32, namely the pressure of a hydraulic system. Flow rate q (x) of the first chamber v1 ,Δp 1 ) The preparation method comprises the following steps:
determining the valve core displacement x of the first load port independent control valve according to the first initial control signal v1 . Determining the pressure difference delta p between two ends of the first load port independent control valve according to the pressure information of the two ends of the valve port of the first load port independent control valve 1 The pressure information of the two ends of the valve port of the first load port independent control valve is the pressure of the working oil port and the two ends of the oil inlet;
the valve core displacement x of the first load port independent control valve v1 And the pressure difference delta p between the two ends of the first load port independent control valve 1 Calculating the flow q of the first cavity corresponding to the first load port independent control valve by combining a flow characteristic model about valve core displacement and valve port differential pressure a ：q a ＝q(x v1 ,Δp 1 )；
Flow rate q (x) of the second chamber v2 Δ p 2) is obtained according to the following steps:
determining the valve core displacement x of the second load port independent control valve according to the second initial control signal v2 . Determining the pressure difference delta p between the two ends of the second load port independent control valve according to the pressure information between the two ends of the valve port of the second load port independent control valve 2 Said second load port being independently controlledThe pressure information at the two ends of the valve port is the pressure of the working oil port and the two ends of the oil inlet;
independently controlling the valve core displacement x of the valve according to the second load port v2 And the pressure difference deltap between the two ends of the second load port independent control valve 2 And calculating the flow q of the second cavity corresponding to the second load port independent control valve by combining a flow characteristic model about valve core displacement and valve port differential pressure b ：q b ＝q(x v2 ,Δp 2 )。
It can be seen from the above embodiments that the speed and pressure control system designed by the present invention has both the characteristics of a composite control system and the characteristics of an independent control system, and it can be seen from the above control logic that the speed and pressure control loops of the present invention are correlated with each other, and the two control circuits compositely control the load port independent control valve corresponding to the hydraulic actuator, specifically, compared with the existing composite control system, the control logic of the present invention can not only reduce the energy consumption of the hydraulic actuator, but also has a simple control logic, compared with the speed and pressure independent loop control system, the control logic of the present invention can reduce the energy consumption of the hydraulic actuator, but also has coupling interference between the speed control loop and the pressure control loop; the invention introduces a feedforward decoupling control unit, can eliminate the coupling interference between a speed control loop and a pressure control loop, can improve the poor dynamic control performance and avoid the occurrence of severe vibration impact.
In addition, in order to improve the dynamic stability of the decoupled system, a two-cavity dynamic pressure feedback control unit is further introduced into the controller, as shown in fig. 5, 6.3 and 6.5 in fig. 5 respectively represent the feedforward coupling amount and the negative feedback amount corresponding to the speed control loop, and 6.4 and 6.6 respectively represent the feedforward coupling amount and the negative feedback amount corresponding to the pressure control loop. The two-cavity dynamic pressure feedback control unit respectively provides a first negative feedback regulating quantity and a second negative feedback regulating quantity for the speed control loop and the pressure control loop so as to simultaneously improve the dynamic stability of the speed control loop and the pressure control loop, and the two dynamic pressure feedback controls do not have mutual interference due to the action of the feedforward decoupling control unit, so that the problem of the aggravation of oscillation caused by the mutual interference of the two dynamic pressure feedback control loops is avoided.
In actual control, the speed control loop adds the first initial control signal, the first feedforward compensation quantity and the first negative feedback adjustment quantity to obtain a first control signal of the first load port independent control valve; and the pressure control loop adds the second initial control signal, the second feedforward compensation quantity and the second negative feedback adjustment quantity to obtain a second control signal of the second load port independent control valve.
The two-cavity dynamic pressure feedback control unit can calculate the first negative feedback regulating quantity u according to the following formula p1 ：
Wherein p is a Indicating the detected pressure of the first chamber, k 1 A first example of a procedure is shown,
representing the combination of the first order inertia element and the differential element, τ c1 Representing the first inertia element time constant, s 1 Representing a transfer function after a first differential element Laplace transform;
the two-cavity dynamic pressure feedback control unit can calculate the second negative feedback regulating quantity u according to the following formula p2 ：
Wherein p is b Indicating the detected pressure of the second chamber, k 2 A second proportional element is shown and indicated,
denotes the combination of the second inertia element and the differential element, τ c2 Representing a second inertial element time constant; s 2 Representing the transfer function after the Laplace transform of the second differential element。
The first-order inertia link and the second-order inertia link are used for respectively adjusting the magnitude of the first control signal and the magnitude of the second control signal, the first proportional link and the second proportional link are used for respectively adjusting the response speed of the first load port independent control valve and the response speed of the second load port independent control valve, and the first differential link and the second differential link are respectively used for acquiring the pressure oscillation characteristics of the first cavity and the second cavity.
Similarly, the flow rate q (x) of the first chamber v1 Δ p 1) is obtained according to the following steps:
determining the valve core displacement x of the first load port independent control valve according to the first initial control signal v1 (ii) a Determining the pressure difference delta p between two ends of the first load port independent control valve according to the pressure information between two ends of the valve port of the first load port independent control valve 1 The pressure information of the two ends of the valve port of the first load port independent control valve is the pressure of the working oil port and the two ends of the oil inlet;
the valve core displacement x of the first load port independent control valve v1 And the pressure difference deltap between the two ends of the first load port independent control valve 1 Calculating the flow q of the first cavity corresponding to the first load port independent control valve by combining a flow characteristic model about valve core displacement and valve port differential pressure a ：q a ＝q(x v1 ,Δp 1 )；
Flow rate q (x) of the second chamber v2 ,Δp 2 ) The preparation method comprises the following steps:
determining the valve core displacement x of the second load port independent control valve according to the second initial control signal v2 (ii) a Determining the pressure difference delta p between the two ends of the second load port independent control valve according to the pressure information of the two ends of the valve port of the second load port independent control valve 2 The pressure information at the two ends of the valve port of the second load port independent control valve is the pressure at the two ends of the working oil port and the oil inlet;
independently controlling the valve core displacement x of the valve according to the second load port v2 And the pressure difference deltap between the two ends of the second load port independent control valve 2 Combined with respect to spool displacement and valve port pressure differentialThe flow characteristic model of the second load port independent control valve calculates the flow q of the second cavity corresponding to the second load port independent control valve b ：q b ＝q(x v2 ,Δp 2 )。
The invention introduces a two-cavity dynamic pressure feedback control unit, obtains a pressure differential signal representing the dynamic stability of the system, and adjusts the control signal through a first-order link and a proportional link, thereby improving the dynamic stability of two independent control loops of speed and pressure while improving the quick response. In addition, the invention realizes the decoupling tracking adjustment of speed and pressure, thereby ensuring the high-dynamic high-precision movement of the hydraulic actuator.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
It will be understood that the invention is not limited to the precise arrangements that have been described above and shown in the drawings, and that various modifications and changes can be made without departing from the scope thereof. The scope of the invention is to be controlled solely by the appended claims.
Claims (7)
1. A load port independent decoupling control system based on speed and pressure feedback is characterized by comprising a hydraulic actuator, two load port independent control valves, two pressure sensors, a speed sensor and a controller, wherein working oil ports corresponding to the two load port independent control valves are respectively connected with two cavities of the hydraulic actuator, and the two pressure sensors respectively send detected pressure information of the two cavities to the controller; the speed sensor sends the detected running speed of the hydraulic actuator to the controller; the controller comprises a speed control loop, a pressure control loop and a feedforward decoupling control unit, wherein the feedforward decoupling control unit provides a first feedforward compensation quantity and a second feedforward compensation quantity for the speed control loop and the pressure control loop respectively so as to eliminate coupling interference between the speed control loop and the pressure control loop;
in actual control, the speed control loop obtains a first initial control signal according to a target speed and a detected running speed, adds the first initial control signal to the first feedforward compensation quantity to obtain a first control signal of a first load port independent control valve, and controls the opening of the first load port independent control valve according to the first control signal, so that the flow entering the hydraulic actuator is controlled, and the speed tracking regulation is realized;
the pressure control loop obtains a second initial control signal according to the target pressure and the detected pressure of the second cavity, adds the second initial control signal to the second feedforward compensation quantity to obtain a second control signal of the second load port independent control valve, and carries out pressure tracking adjustment based on the detected pressure of the second cavity;
the feedforward decoupling control unit calculates the first feedforward compensation quantity u according to the following formula according to the detected running speed of the hydraulic actuator f1 ：
Wherein v is cy Indicating the detected running speed, q (x) v1 ,Δp 1 ) Denotes the flow of the first chamber, A a The working area of the first chamber is shown,
ω v1 representing the natural frequency, s, of the first load port independent control valve 1 Representing a transfer function after Laplace transform of a first differential link;
the feedforward decoupling control unit calculates the second feedforward compensation quantity u according to the following formula according to the detected running speed of the hydraulic actuator f2 ：
Wherein v is cy Indicating the detected speed of operation, q (x) v2 ,Δp 2 ) Indicating the flow of the second chamber, A b The working area of the second chamber is shown,
ω v2 representing the natural frequency, s, of the second load port independent control valve 2 Representing a transfer function after Laplace transform of a second differential link;
the speed control loop obtaining a first initial control signal according to the target speed and the detected running speed comprises: comparing the target speed with the detected running speed, calculating a speed difference value, and inputting the speed difference value into a PID speed regulator to obtain the first initial control signal;
the pressure control circuit obtaining a second initial control signal based on the target pressure and the sensed pressure of the second chamber comprises: comparing the target pressure with the detected pressure of the second cavity, calculating a pressure difference value, and inputting the pressure difference value to a PID speed regulator to obtain the second initial control signal;
when the hydraulic actuator extends out, the speed control loop compares a target speed with a detected running speed, calculates a speed difference value, and inputs the speed difference value into a PID speed regulator to obtain the first initial control signal; the pressure control loop compares a target pressure with the detected pressure of the second cavity, calculates a pressure difference value, inputs the pressure difference value into a PID speed regulator to obtain a second initial control signal, and sets the target pressure to be as low as 2bar so as to reduce outlet throttling loss;
when the hydraulic actuator retracts, the speed control loop compares a target speed with a detected running speed, calculates a speed difference value, and inputs the speed difference value into a PID speed regulator to obtain a second initial control signal; and the pressure control loop compares the target pressure with the detected pressure of the second cavity, calculates a pressure difference value, inputs the pressure difference value into a PID speed regulator, and obtains the first initial control signal, wherein the target pressure is set to be as low as 2bar so as to reduce the outlet throttling loss.
2. The speed and pressure feedback based load port independent decoupling control system of claim 1, wherein the control unit further comprises a two-chamber dynamic pressure feedback control unit, the two-chamber dynamic pressure feedback control unit providing a first negative feedback adjustment amount and a second negative feedback adjustment amount to the speed control loop and the pressure control loop, respectively, to improve dynamic stability of the speed control loop and the pressure control loop;
in actual control, the speed control loop adds the first initial control signal, the first feedforward compensation quantity and the first negative feedback adjustment quantity to obtain a first control signal of the first load port independent control valve; and the pressure control loop adds the second initial control signal, the second feedforward compensation quantity and the second negative feedback adjustment quantity to obtain a second control signal of the second load port independent control valve.
3. The speed and pressure feedback-based load port independent decoupling control system of claim 2, wherein the two-chamber dynamic pressure feedback control unit calculates the first negative feedback adjustment u according to the following formula p1 ：
Wherein p is a Indicating the detected pressure of the first chamber, k 1 A first example of a procedure is shown,
representing first order inertiaCombining links with differentiating links, tau c1 Represents the first inertia element time constant, s 1 Representing a transfer function after a first differential element Laplace transform;
the two-cavity dynamic pressure feedback control unit calculates the second negative feedback regulating quantity u according to the following formula p2 ：
Wherein p is b Indicating the detected pressure of the second chamber, k 2 A second proportional segment is shown and indicated,
representing the combination of the second-order inertia element and the differential element, tau c2 Representing a second inertial element time constant; s is 2 Representing the transfer function after the second differential-element laplace transform.
4. The speed and pressure feedback based load port independent decoupling control system according to claim 3, wherein the first order inertia element and the second order inertia element are used for adjusting the magnitude of the first control signal and the second control signal respectively, the first proportional element and the second proportional element are used for adjusting the response speed of the first load port independent control valve and the second load port independent control valve respectively, and the first differential element and the second differential element are used for obtaining the pressure oscillation characteristics of the first cavity and the second cavity respectively.
5. The speed and pressure feedback based load port independent decoupling control system according to claim 1 or 3, wherein the pressure information of the two chambers detected by the two pressure sensors is the pressure at the working oil port of the first load port independent control valve and the pressure at the working oil port of the second load port independent control valve; the oil inlets of the first load port independent control valve and the second load port independent control valve are connected, and a third pressure sensor is arranged at the connection node and used for detecting the pressure at the oil inlets of the first load port independent control valve and the second load port independent control valve;
flow rate q (x) of the first chamber v1 ,Δp 1 ) The preparation method comprises the following steps:
determining the valve core displacement x of the first load port independent control valve according to the first initial control signal v1 (ii) a Determining the pressure difference delta p between two ends of the first load port independent control valve according to the pressure information between two ends of the valve port of the first load port independent control valve 1 The pressure information of the two ends of the valve port of the first load port independent control valve is the pressure of the working oil port and the two ends of the oil inlet;
the valve core displacement x of the first load port independent control valve v1 And the pressure difference deltap between the two ends of the first load port independent control valve 1 Calculating the flow q of the first cavity corresponding to the first load port independent control valve by combining a flow characteristic model about valve core displacement and valve port differential pressure a ：q a ＝q(x v1 ,Δp 1 )；
Flow rate q (x) of the second chamber v2 ,Δp 2 ) The preparation method comprises the following steps:
determining the valve core displacement x of the second load port independent control valve according to the second initial control signal v2 (ii) a Determining the pressure difference delta p between the two ends of the second load port independent control valve according to the pressure information between the two ends of the valve port of the second load port independent control valve 2 The pressure information at the two ends of the valve port of the second load port independent control valve is the pressure at the two ends of the working oil port and the oil inlet;
independently controlling the valve core displacement x of the valve according to the second load port v2 And the pressure difference deltap between the two ends of the second load port independent control valve 2 And calculating the flow q of the second cavity corresponding to the second load port independent control valve by combining a flow characteristic model about valve core displacement and valve port differential pressure b ：q b ＝q(x v2 ,Δp 2 )。
6. The speed and pressure feedback-based load port independent decoupling control system of claim 1, wherein the first and second feedforward compensation amounts are derived by: establishing a composite physical model of the speed control loop and the pressure control loop;
in the composite physical model, theoretically, the pressure control loop obtains the second initial control signal according to a target pressure and the detected pressure of the second cavity; calculating the flow of the second cavity according to the second initial control signal; calculating the pressure of the second cavity according to the flow of the second cavity, the detected running speed and the working area of the second cavity, and performing pressure tracking adjustment based on the detected pressure of the second cavity;
the speed control loop obtains the first initial control signal according to a target speed and the detected running speed; calculating the flow of the first cavity according to the first control signal; calculating the pressure of the first cavity according to the flow of the first cavity, the detected running speed and the working area of the first cavity, calculating the running speed according to the calculated pressures of the first cavity and the second cavity, and performing speed tracking adjustment based on the calculated running speed;
and analyzing that the interference of the first cavity on the second cavity is related to the operation speed and the working area of the second cavity according to a calculation formula of the pressure of the second cavity and the operation speed, and the interference of the second cavity on the first cavity is related to the operation speed and the working area of the first cavity.
7. The speed and pressure feedback based load port independent decoupling control system of claim 6, wherein said pressure control loop calculates said second chamber pressure p based on said second chamber flow, sensed operating speed and working area of said second chamber according to the following equation b ：
Wherein
V b Denotes the volume of the second chamber, beta e2 Denotes the modulus of elasticity, q, of the oil in the second chamber b Indicating the flow of the second chamber, A b Denotes the working area of the second chamber, v cy Indicating a detected operating speed;
the speed control loop calculates the pressure p of the first cavity according to the following formula according to the flow of the first cavity, the detected running speed and the working area of the first cavity a ：
Wherein
V a Denotes the first chamber volume, beta e1 Expressing the modulus of elasticity, q, of the oil in the first chamber a Denotes the flow of the first chamber, A a Denotes the working area of the first chamber, v cy Indicating a detected operating speed;
the speed control loop calculates the pressure p of the first cavity a And pressure p of the second chamber b The running speed v is calculated according to the following formula cy ：
Where m denotes the equivalent load mass of the hydraulic actuator, p a Denotes the pressure of the first chamber, A a Denotes the working area of the first chamber, p b Denotes the pressure of the second chamber, A b Denotes the working area of the second chamber, F L Representing the load force of the hydraulic actuator;
and analyzing and determining the first feedforward compensation amount and the second feedforward compensation amount according to the formula.
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