阅读说明：本技术 一种基于电磁比例阀的电液执行器系统及其位移控制方法 (Electro-hydraulic actuator system based on electromagnetic proportional valve and displacement control method thereof ) 是由 张辉 张思龙 于 2021-06-28 设计创作，主要内容包括：本发明提出了一种基于电磁比例阀的电液执行器系统及其位移控制方法,通过三位四通电磁阀控制流体流向,建立数学模型,并采用PID控制器对液压作动器进行位移精确控制,从而有效解决了现有电液执行器位置控制系统控制精度低、响应慢的问题,实现了对电液执行器的高动态响应、低跟踪误差的位置精确控制。(The invention provides an electro-hydraulic actuator system based on an electromagnetic proportional valve and a displacement control method thereof.)

1. An electro-hydraulic actuator system based on an electromagnetic proportional valve is characterized by comprising a three-position four-way electromagnetic proportional valve (1), a displacement pump (2), a double-action hydraulic piston cylinder (3), a position sensor (4) and an oil tank (5); the three-position four-way electromagnetic proportional valve (1) is respectively connected with the double-action hydraulic piston cylinder (3), the displacement pump (2) and the oil tank (5) through hydraulic pipelines; and the position sensor (4) is connected with the piston of the double-action hydraulic piston cylinder (3) to measure the actual position of the piston of the double-action hydraulic piston cylinder.

2. The electro-hydraulic actuator system of claim 1, wherein the three-position four-way solenoid proportional valve (1) controls fluid flow, maintaining flow and actuator pressure by controlling the opening of proportional valve ports.

3. The electro-hydraulic actuator system of claim 1, wherein the displacement pump (2) is coupled to the electric motor as a source of pressurized power to provide a constant pressurized fluid to the system.

4. The electro-hydraulic actuator system of claim 1, further comprising a pressure regulating valve (6), the pressure regulating valve (6) acting as a system relief valve.

5. A displacement control method using the electro-hydraulic actuator system of any one of claims 1-4, comprising the steps of:

s1, establishing a dynamic model of an actuating mechanism of the electro-hydraulic actuator system:

wherein A is_kIs the piston area, M is the piston external load mass,in order to accelerate the actuator, the acceleration of the actuator is measured,is the actuator speed, C is the leakage coefficient, P₁And P₂The pressures of the left piston cavity and the right piston cavity are respectively;

the pressure of the left piston cavity and the right piston cavity of the actuator is as follows:

wherein beta is the fluid bulk modulus, V_hIs half the volume of the actuator, Q₁、Q₂Flow into and out of the actuator, Q, respectively_LFor flow leaking from one chamber to another through the annular piston area, Y is the displacement of the actuator piston;

flow rate Q of the inflow actuator and the outflow actuator₁、Q₂And a meterLeakage flow rate Q_LCalculated from the following formula:

in the formula, C_dIs the flow coefficient, A_PMetering the area of a port for a three-position four-way electromagnetic proportional valve, wherein rho is the fluid density and P is_sPressure supplied to the pump, P_rIs the reservoir pressure, d_kTo the actuator diameter, h_sIs a ring gap of_sIs the length of the valve core;

the method for calculating the area of the metering port of the three-position four-way electromagnetic proportional valve comprises the following steps:

wherein r is radius of a metering port of the three-position four-way electromagnetic proportional valve, x_SPThe valve core of the three-position four-way electromagnetic proportional valve is displaced;

the three-position four-way electromagnetic proportional valve drives the valve core after being electrified, and the relationship between the current and the displacement of the valve core is as follows:

x_SP＝f(I_SC)

wherein, I_scThe current of the three-position four-way electromagnetic proportional valve;

s2, the position of the electro-hydraulic actuator is controlled by adopting a closed-loop PID controller, the position sensor feeds back a piston displacement signal to the PID controller in real time, and the PID controller inputs an expected input variable Y_dDifference with piston displacement Y to obtain displacement tracking error, i.e. e ═ Y_d-Y, PID controller tracking error according to displacementCalculating the difference e to obtain a duty ratio eta, wherein eta is more than or equal to 0 and less than or equal to 1, and driving the three-position four-way electromagnetic proportional valve to act through current to adjust the pressure of the left piston cavity and the pressure of the right piston cavity so that the piston displacement Y of the electro-hydraulic actuator gradually reaches the expected displacement Y_dAnd completing the displacement closed-loop control of the electro-hydraulic actuator.

Technical Field

The invention relates to the field of electro-hydraulic actuators, in particular to a method for controlling the accurate position of an electro-hydraulic actuator.

Background

The electro-hydraulic actuator system is widely applied to various industrial fields. The system is characterized by the ability to deliver large forces and high dynamic response, and has high durability and high power-to-weight ratio, and can provide large forces at high speeds in relatively small size. In recent years, high-precision position control of electro-hydraulic actuator systems has received much attention, and various electro-hydraulic actuator systems and control schemes thereof have been widely applied to the fields of mobile equipment, machine tools, plastic industry, automobile detection, mine oil exploration and the like.

Disclosure of Invention

Aiming at the application requirements of the electro-hydraulic actuator, the invention provides an electro-hydraulic actuator system based on an electromagnetic proportional valve and a displacement control method thereof.

The technical scheme of the invention is as follows:

an electro-hydraulic actuator system based on a solenoid proportional valve, comprising: the device comprises a three-position four-way electromagnetic proportional valve 1, a displacement pump 2, a double-acting hydraulic piston cylinder 3, a position sensor 4 and an oil tank 5;

the three-position four-way electromagnetic proportional valve 1 is respectively connected with the double-action hydraulic piston cylinder 3, the displacement pump 2 and the oil tank 5 through hydraulic pipelines;

and the position sensor 4 is connected with the piston of the double-acting hydraulic piston cylinder 3 to measure the actual position of the piston of the double-acting hydraulic piston cylinder.

Further, the three-position four-way electromagnetic proportional valve 1 controls the flow direction of fluid, and keeps the flow and the pressure of an actuator by controlling the opening of a port of the proportional valve.

Further, the displacement pump 2 is used as a pressurizing power source and is coupled with an electric motor to provide constant pressurized fluid for the system.

Further, a pressure regulating valve 6 is included as a system safety valve.

A displacement control method using the electro-hydraulic actuator system comprises the following steps:

s1, establishing a dynamic model of an actuating mechanism of the electro-hydraulic actuator system:

wherein A is_kIs the piston area, M is the piston external load mass,in order to accelerate the actuator, the acceleration of the actuator is measured,is the actuator speed, C is the leakage coefficient, P₁And P₂The pressures of the left and right piston chambers are shown respectively.

The pressure of the left piston cavity and the right piston cavity of the actuator is as follows:

wherein beta is the fluid bulk modulus, V_hIs half the volume of the actuator, Q₁、Q₂Flow into and out of the actuator, Q, respectively_LFor flow leaking from one chamber to another through the annular piston area, Y is the displacement of the actuator piston.

Flow rate Q of the inflow actuator and the outflow actuator₁、Q₂And meter the leakage flow rate Q_LCalculated from the following formula:

in the formula, C_dIs the flow coefficient, A_PMetering the area of a port for a three-position four-way electromagnetic proportional valve, wherein rho is the fluid density and P is_sPressure supplied to the pump, P_rFor reservoir pressureForce, d_kTo the actuator diameter, h_sIs a ring gap of_sIs the spool length.

The method for calculating the area of the metering port of the three-position four-way electromagnetic proportional valve comprises the following steps:

wherein r is radius of a metering port of the three-position four-way electromagnetic proportional valve, x_SPThe valve core of the three-position four-way electromagnetic proportional valve is displaced.

The three-position four-way electromagnetic proportional valve drives the valve core after being electrified, and the relationship between the current and the displacement of the valve core is as follows:

x_SP＝f(I_SC)

wherein, I_scIs the current of the three-position four-way electromagnetic proportional valve.

S2, the position of the electro-hydraulic actuator is controlled by adopting a closed-loop PID controller, the position sensor feeds back a piston displacement signal to the PID controller in real time, and the PID controller inputs an expected input variable Y_dDifference with piston displacement Y to obtain displacement tracking error, i.e. e ═ Y_dY, the PID controller calculates and obtains a duty ratio eta according to the displacement tracking error e, wherein eta is more than or equal to 0 and less than or equal to 1, and drives the three-position four-way electromagnetic proportional valve to act through current to adjust the pressure of the left piston cavity and the right piston cavity so that the piston displacement Y of the electro-hydraulic actuator gradually reaches the expected displacement Y_dAnd completing the displacement closed-loop control of the electro-hydraulic actuator.

Compared with the prior art, the technical scheme of the invention adopts the three-position four-way electromagnetic valve to control the flow direction of the fluid, establishes a reliable mathematical model in a pertinence way, and realizes the position accurate control of high dynamic response and low tracking error of the electro-hydraulic actuator by matching with the PID controller.

Drawings

The invention may be better understood by reference to the following drawings. The components in the figures are not to be considered as drawn to scale, emphasis instead being placed upon illustrating the principles of the invention.

FIG. 1 is a schematic view of an electro-hydraulic actuator system of the present invention;

Detailed Description

For the purpose of facilitating an understanding and practicing the invention by those of ordinary skill in the art, the invention is described in further detail below with reference to the following detailed description of illustrative embodiments and drawings:

as shown in fig. 1, the electro-hydraulic actuator system based on the electromagnetic proportional valve of the present invention includes: the device comprises a three-position four-way electromagnetic proportional valve 1, a displacement pump 2, a double-acting hydraulic piston cylinder 3, a position sensor 4 and an oil tank 5; the three-position four-way electromagnetic proportional valve 1 is respectively connected with the double-action hydraulic piston cylinder 3, the displacement pump 2 and the oil tank 5 through hydraulic pipelines; and the position sensor 4 is connected with the piston of the double-acting hydraulic piston cylinder 3 to measure the actual position of the piston of the double-acting hydraulic piston cylinder.

The three-position four-way electromagnetic proportional valve 1 controls the flow direction of fluid, and keeps the flow and the pressure of an actuator by controlling the opening of a port of the proportional valve.

The displacement pump 2 is used as a pressurizing power source and is coupled with the motor to form a structure, and constant pressurized fluid is provided for the system.

And a pressure regulating valve 6 as a system safety valve.

A displacement control method using the electro-hydraulic actuator system comprises the following steps:

s1, establishing a dynamic model of an actuating mechanism of the electro-hydraulic actuator system:

wherein A is_kIs the piston area, M is the piston external load mass,in order to accelerate the actuator, the acceleration of the actuator is measured,is the actuator speed, C is the leakage coefficient, P₁And P₂The pressures of the left and right piston chambers are shown respectively.

The pressure of the left piston cavity and the right piston cavity of the actuator is as follows:

wherein beta is the fluid bulk modulus, V_hIs half the volume of the actuator, Q₁、Q₂Flow into and out of the actuator, Q, respectively_LFor flow leaking from one chamber to another through the annular piston area, Y is the displacement of the actuator piston.

Flow rate Q of the inflow actuator and the outflow actuator₁、Q₂And meter the leakage flow rate Q_LCalculated from the following formula:

in the formula, C_dIs the flow coefficient, A_PMetering the area of a port for a three-position four-way electromagnetic proportional valve, wherein rho is the fluid density and P is_sPressure supplied to the pump, P_rIs the reservoir pressure, d_kTo the actuator diameter, h_sIs a ring gap of_sIs the spool length.

The method for calculating the area of the metering port of the three-position four-way electromagnetic proportional valve comprises the following steps:

wherein r is radius of a metering port of the three-position four-way electromagnetic proportional valve, x_SPThe valve core of the three-position four-way electromagnetic proportional valve is displaced.

The three-position four-way electromagnetic proportional valve drives the valve core after being electrified, and the relationship between the current and the displacement of the valve core is as follows:

x_SP＝f(I_SC)

wherein, I_scIs the current of the three-position four-way electromagnetic proportional valve.

S2, the position of the electro-hydraulic actuator is controlled by adopting a closed-loop PID controller, the position sensor feeds back a piston displacement signal to the PID controller in real time, and the PID controller inputs an expected input variable Y_dDifference with piston displacement Y to obtain displacement tracking error, i.e. e ═ Y_dY, the PID controller calculates and obtains a duty ratio eta according to the displacement tracking error e, wherein eta is more than or equal to 0 and less than or equal to 1, and drives the three-position four-way electromagnetic proportional valve to act through current to adjust the pressure of the left piston cavity and the right piston cavity so that the piston displacement Y of the electro-hydraulic actuator gradually reaches the expected displacement Y_dAnd completing the displacement closed-loop control of the electro-hydraulic actuator.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, a first feature being "on," "above" or "over" a second feature includes the first feature being directly on or obliquely above the second feature, or simply indicating that the first feature is at a higher level than the second feature. A first feature being "under", beneath and "under" a second feature includes the first feature being directly under and obliquely under the second feature, or simply means that the first feature is at a lesser elevation than the second feature.

In the present invention, the terms "first", "second", third "and" fourth "are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. The term "plurality" means two or more unless expressly limited otherwise.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.