CN114673711B - Cylinder position control method based on five-mode switching of high-speed switch valve - Google Patents

Cylinder position control method based on five-mode switching of high-speed switch valve Download PDF

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CN114673711B
CN114673711B CN202210313024.7A CN202210313024A CN114673711B CN 114673711 B CN114673711 B CN 114673711B CN 202210313024 A CN202210313024 A CN 202210313024A CN 114673711 B CN114673711 B CN 114673711B
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cylinder
valve
air
air inlet
cavity
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CN114673711A (en
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王涛
王昱衡
孙志涵
王波
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Beijing Institute of Technology BIT
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/08—Characterised by the construction of the motor unit
    • F15B15/14—Characterised by the construction of the motor unit of the straight-cylinder type
    • F15B15/1423—Component parts; Constructional details
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/20—Other details, e.g. assembly with regulating devices
    • F15B15/22—Other details, e.g. assembly with regulating devices for accelerating or decelerating the stroke
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/20—Other details, e.g. assembly with regulating devices
    • F15B15/28—Means for indicating the position, e.g. end of stroke
    • F15B15/2815—Position sensing, i.e. means for continuous measurement of position, e.g. LVDT
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/755—Control of acceleration or deceleration of the output member
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/765—Control of position or angle of the output member

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  • Physics & Mathematics (AREA)
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  • General Engineering & Computer Science (AREA)
  • Servomotors (AREA)
  • Fluid-Pressure Circuits (AREA)

Abstract

The invention relates to a cylinder position control method based on five-mode switching of a high-speed switch valve, and belongs to the field of pneumatic servo control. According to the invention, five different working modes of rapid rightward movement, slow rightward movement, complete closing, rapid leftward movement and slow leftward movement of the piston are adopted, so that the time for completely opening the high-speed switch valve is utilized to the greatest extent, and the consumption of gas is saved. And by applying a displacement error signal e 0 Rate of change of displacement error
Figure DDA0003567852130000011
The specific working mode of the system is judged by the calculation and the introduced threshold epsilon, the response speed of the system is improved, and the gas waste caused by frequent switching of the working state of the high-speed switch valve is reduced. In addition, by designing an extended state observer and a nonlinear error feedback control law, nonlinear factors of a nonlinear region and a system structure in PWM control are effectively compensated, a five-mode switching active disturbance rejection controller is designed, and the control precision of the cylinder position based on a high-speed switch valve is improved.

Description

Cylinder position control method based on five-mode switching of high-speed switch valve
Technical Field
The invention relates to a cylinder position control method based on five-mode switching of a high-speed switch valve, in particular to a cylinder position servo control method based on five-mode switching of a full-bridge loop of the high-speed switch valve, and belongs to the field of pneumatic servo control.
Background
The pneumatic technology uses compressed air as a working medium to transfer and control energy and signals, and is an important technology for realizing production automation. Pneumatic control valves are critical to achieving high accuracy control and rapid response to gas pressure. Digital pneumatic is one of the future development directions of pneumatic technology, wherein a high-speed switch valve as a core element of the digital pneumatic has the advantages of strong pollution resistance, low price, no need of additionally adding a D/A conversion module and the like, and is increasingly applied to a cylinder position control system. In a cylinder position control system based on a high-speed switch valve, a pulse width modulation (Pulse Width Modulation, PWM) technology is generally adopted to realize the function of approximate proportional control of the high-speed switch valve. Because two high-speed switch valves are needed for controlling air intake and air exhaust of two cavities of the cylinder respectively, four two-position two-way high-speed circuits Guan Fazu are generally adopted to form a full-bridge loop for controlling the position of the cylinder.
The cylinder position positioning and track tracking control precision is lower due to the existence of factors such as the compressibility of gas, the friction force of a cylinder piston in motion, the inertial load of the cylinder, the nonlinearity of the output flow of the high-speed switch valve and the like. When the open loop control system is disturbed, the system has no function of eliminating or reducing errors once the cylinder position deviates from the original balance state. The traditional PID control algorithm can not solve the problems of low control precision and the like caused by the flow nonlinearity of the high-speed switch valve. In the cylinder position servo control system based on the full-bridge loop of the high-speed switch valves, the four high-speed switch valves are required to be frequently switched, and the high-speed switch valves cannot be completely opened under the control of PWM signals, so that the gas charging and discharging rates cannot reach the maximum all the time, the response speed is lower, and the control signals of the four high-speed switch valves are required to be reasonably distributed.
Disclosure of Invention
Aiming at the problems of low response speed, high gas loss and low control precision caused by the traditional non-supercharged switching strategy, the invention discloses a cylinder position control method based on five-mode switching of a high-speed switch valve, which aims to improve the response speed and control precision of cylinder position control and reduce the gas loss.
The aim of the invention is realized by the following technical scheme:
the cylinder position servo control system of the high-speed switching valve full-bridge loop comprises: the device comprises an air source, a rodless cylinder, two air inlet valves, two exhaust valves, a displacement sensor and a controller;
the air inlets of the air inlet valve A and the air inlet valve B are connected with an air source, the air outlet of the air inlet valve A is connected with the cylinder accommodating cavity A, and the air outlet of the air inlet valve B is connected with the cylinder accommodating cavity B;
the air inlet of the exhaust valve A is connected with the cylinder accommodating cavity A, the air inlet of the exhaust valve B is connected with the cylinder accommodating cavity B, and the air outlets of the exhaust valve A and the exhaust valve B are communicated with the atmospheric environment;
the displacement sensor is arranged on the rodless cylinder, and the displacement sensor measures the position of the piston in the controlled cylinder and feeds back the position to the control board;
the four-way PWM signal output ends of the controller are connected with the signal input ends of the air inlet valve A, the air inlet valve B, the air outlet valve A and the air outlet valve B;
the controller is based on the displacement error signal e 0 And the preset threshold epsilon controls the working states of the four valves to be divided into five different working modes of quick rightward movement, slow rightward movement, quick leftward movement, slow leftward movement and complete closing of the cylinder piston.
A cylinder position control method based on five-mode switching of a high-speed switch valve is based on a cylinder position servo system of a full-bridge loop of the high-speed switch valve, and the system is controlled to realize efficient and accurate control on cylinder position positioning.
Step one, calculating a displacement error e of a cylinder piston 0 And preset a threshold value epsilon, when |e 0 When the I is less than or equal to epsilon, the system enters a full-closed mode, frequent switching of the high-speed switch valve is avoided, and meanwhile gas consumption is saved.
Step two, when |e 0 |>Respectively calculating displacement errors e when epsilon 0 And rate of change of displacement error
Figure BDA0003567852110000021
The membership function of the fast segment and the slow segment is calculated again f And delta s ；
Figure BDA0003567852110000022
Figure BDA0003567852110000023
Wherein a represents a displacement error e 0 B represents the rate of change of displacement error
Figure BDA0003567852110000024
Is not limited in terms of the range of (a).
δ f ＝U e ·U ec ，δ s ＝1-δ f (3)
Step three, when the displacement error e 0 >Epsilon and delta f <δ s The air inlet valve A and the air outlet valve B are controlled by PWM signals, the duty ratio of the two PWM signals is u, and the air inlet valve B and the air outlet valve A are completely closed, at the moment, the cavity A of the rodless cylinder is in air inlet and the cavity B is in air outlet, so that the piston of the cylinder moves rightwards slowly.
Step four, when the displacement error e 0 <-epsilon and delta f <δ s The air inlet valve B and the air outlet valve A are controlled by PWM signals, the duty ratio of the two PWM signals is u, and the air inlet valve A and the air outlet valve B are completely closed, at the moment, the cavity of the rodless cylinder B is filled with air and the cavity A is exhausted, so that the piston of the cylinder moves leftwards slowly.
Step five, when e 0 >Epsilon and delta f ≥δ s The intake valve a and the exhaust valve B are fully opened and the intake valve B and the exhaust valve a are fully closed, at which time the rodless cylinder a chamber is charged and the B chamber is exhausted, so the piston of the cylinder is rapidly moved to the right.
Step six, when e 0 <-epsilon and delta f ≥δ s The intake valve B and the exhaust valve a are fully opened and the intake valve a and the exhaust valve B are fully closed, at which time the rodless cylinder a chamber is charged and the B chamber is exhausted, so that the piston of the cylinder is rapidly moved leftward.
And step seven, a model of a cylinder position servo control system of the high-speed switching valve is as follows:
Figure BDA0003567852110000031
Figure BDA0003567852110000032
Figure BDA0003567852110000033
wherein M is the mass of a rodless cylinder piston and a load carried by the rodless cylinder piston; x is cylinder displacement; p is p a 、p b The gas pressure in the A, B chambers; s is S a Is the piston area of the A cavity, S b The piston area of the cavity B; s is S a And S is b The areas are equal; f (F) f Is the friction force applied to the rodless cylinder; f is other unmodeled dynamics and external disturbances; k is the air insulation index; r is an ideal gas constant; t (T) s Is the temperature of the air source; l is the length of the cylinder; q ma 、q mb The mass flow rate of the gas flowing into the A cavity and the B cavity is respectively F c Coulomb friction force for the cylinder; c is the viscous drag coefficient of the cylinder; f (F) s Representing the maximum static friction of the cylinder.
Let x 1 ＝x，
Figure BDA0003567852110000034
y＝x 1 Changing the formula (6) into a form of a state space, namely, the formula (7):
Figure BDA0003567852110000035
wherein u is a control amount,
Figure BDA0003567852110000036
b, as the total disturbance of the system 0 Is a system gain estimate.
Figure BDA0003567852110000037
Figure BDA0003567852110000038
Step eight, designing a third-order active disturbance rejection controller of a system five-mode switching strategy according to the formula (7) and the steps one to six:
Figure BDA0003567852110000039
Figure BDA0003567852110000041
wherein v is 0 For a given position reference signal, v 1 V is 0 V 2 V is 1 V of the differential signal of (v) 3 V is 2 R is the speed factor of the tracking differentiator; y is the system output, z 1 ,z 2 ,z 3 Z is the observed value of the system state 4 Is the observed value of the total disturbance of the system, beta 1 ,β 2 ,β 3 ,β 4 B for the extended state observer parameters 0 Estimating a system gain; k (k) 1 ,k 2 ,k 3 Is a nonlinear feedback control law parameter, a 1 ,a 2 ,a 3 Delta is a nonlinear fal function parameter; e, e 0 For displacement error, u is the voltage control quantity of the position of the cylinder switched in five modes, and epsilon is a preset threshold value;
and step nine, outputting the control quantity u obtained according to the formula (10) in the step eight to a signal input end of a corresponding high-speed switch valve through a DO port of a controller, and acting on a high-speed switch valve cylinder position system to realize quick and accurate positioning of the cylinder position. The response speed of the cylinder position control and the cylinder position positioning precision are obviously improved, the gas loss is reduced, and the energy is saved.
The beneficial effects are that:
1. the invention utilizes the normally open time of the switch valve to the maximum extent through the five-mode switching strategy, improves the response speed, reduces the gas waste caused by frequent switching of the working state of the high-speed switch valve, and improves the positioning precision and the rapidity of the action in a system using the cylinder to position, such as the work of a pneumatic manipulator, and has higher working efficiency.
2. The invention effectively compensates nonlinear regions existing in PWM control and nonlinear factors of the system by the extended state observer and the nonlinear error feedback control law, thereby improving the displacement control precision.
Drawings
FIG. 1 is a schematic diagram of a cylinder position control system based on five-mode switching of a high-speed switching valve;
FIG. 2 is a block diagram of a control system of the present invention;
FIG. 3 is a graph of a switching membership function for displacement error and rate of change of displacement error;
fig. 4 is a graph of sinusoidal signal tracking with load of 0.5 Hz.
Wherein, 1-air inlet valve A, 2-air outlet valve A, 3-air inlet valve B, 4-air outlet valve B, 5-air source, 6-rodless cylinder, 7-displacement sensor, 8-controller.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings and examples. While technical problems and advantages achieved by the technical solution of the present invention have been described, it should be noted that the examples described are only intended to facilitate the understanding of the present invention and are not intended to limit the present invention in any way.
As shown in FIG. 1, the pneumatic control system based on five-mode switching of the high-speed switch valve structurally comprises four high-speed switch valves, namely an air inlet valve A1, an air outlet valve A2, an air inlet valve B3, an air outlet valve B4, an air source 5, a rodless cylinder 6, a displacement sensor 7 and a controller 8. The air inlets of the air inlet valve A1 and the air inlet valve B3 are connected with the air source 5, the air outlets of the air inlet valve A1 and the air inlet valve B3 are connected with the rodless cylinder 6, the air inlets of the exhaust valve A2 and the exhaust valve B4 are connected with the rodless cylinder 6, the air outlets of the exhaust valve A2 and the exhaust valve B4 are communicated with the atmosphere, a displacement sensor 7 is arranged on the rodless cylinder 6, the displacement sensor 7 measures the position of a piston in a controlled cylinder and feeds back the position to the controller 6, and four paths of PWM signal output ends of the controller 6 are respectively connected with the signal input ends of the air inlet valve A1, the air inlet valve B3, the exhaust valve A2 and the exhaust valve B4.
The air source pressure provided by the air source 5 is 0.6Mpa; the air inlet valve A1, the air inlet valve B3, the air outlet valve A2 and the air outlet valve B4 adopt two-position two-way electromagnetic high-speed switch valves, and the switch frequency can reach 150Hz; the controller is an embedded controller (ARM microcontroller S32K 142) with AD acquisition function and PWM signal output function. The load carried by the rodless cylinder 6 is 1kg, the cylinder stroke is 100mm, and the volumes of the pistons of the cavity A and the cavity B are 10.6ml. The displacement setting of the cylinder position control system is 30mm or follows a sine curve with amplitude of 30mm, frequency of 0.5Hz and 1 Hz.
The working process of the cylinder position control method based on the five-mode switching of the high-speed switch valve is described as follows: according to the displacement error signal e 0 Conversion rate of displacement error
Figure BDA0003567852110000051
And an introduced threshold epsilon (epsilon)>0) The working states of the four high-speed switch valves are divided into 5 different working modes, namely, the working modes are completely closed, the cavity A is filled with air, the cavity B is exhausted, the piston moves right quickly/slowly, the cavity A is exhausted, the cavity B is filled with air, and the piston moves left quickly/slowly as shown in a table 1. When the absolute value of displacement error is very close to the threshold value, the system is enabled to enter into all closing sections, and the air inlet valve and the air outlet valve are completely closed, so that the gas waste caused by frequent switching of the working state of the high-speed switch valve is reduced.
Table 1 five mode switching strategy
Figure BDA0003567852110000052
As shown in fig. 2, the specific steps of the cylinder position control method based on the five-mode switching of the high-speed switch valve are implemented:
step 1, calculating a cylinder piston displacement error e 0 And preset a threshold value epsilon, when |e 0 When the I is less than or equal to epsilon, the system enters a full-closed mode, frequent switching of the high-speed switch valve is avoided, and meanwhile gas consumption is saved. Epsilon=0.1 during the implementation.
Step 2, when |e 0 |>When epsilon, calculate the displacement error e 0 And rate of change of displacement error
Figure BDA0003567852110000053
Further computing fast and slow output intensity coefficients delta f And delta s As shown in fig. 3.
Figure BDA0003567852110000054
Figure BDA0003567852110000061
Wherein a represents a displacement error e 0 B represents the rate of change of displacement error
Figure BDA0003567852110000062
Is not limited in terms of the range of (a).
δ f ＝U e ·U ec ，δ s ＝1-δ f (14)
Step 3, when the displacement error e 0 >Epsilon and delta f <δ s The air inlet valve A and the air outlet valve B are controlled by PWM signals, the duty ratio of the two PWM signals is u, and the air inlet valve B and the air outlet valve A are completely closed, at the moment, the cavity A of the rodless cylinder is in air inlet and the cavity B is in air outlet, so that the piston of the cylinder moves rightwards slowly.
Step 4, when the displacement error e 0 <-epsilon and delta f <δ s The air inlet valve B and the air outlet valve A are controlled by PWM signals, the duty ratio of the two PWM signals is u, and the air inlet valve A and the air outlet valve B are completely closed, at the moment, the cavity of the rodless cylinder B is filled with air and the cavity A is exhausted, so that the piston of the cylinder moves leftwards slowly.
Step 5, when e 0 >Epsilon and delta f ≥δ s The intake valve A and the exhaust valve B are fully opened, the intake valve B and the exhaust valve A are fully closed, and the cavity A of the rodless cylinder is filled with air and the cavity B is exhausted, so that the cylinder is aliveThe plug is rapidly moved to the right.
Step 6, when e 0 <-epsilon and delta f ≥δ s The intake valve B and the exhaust valve a are fully opened and the intake valve a and the exhaust valve B are fully closed, at which time the rodless cylinder a chamber is charged and the B chamber is exhausted, so that the piston of the cylinder is rapidly moved leftward.
Step 7, a mathematical model of the cylinder position servo control system for the high-speed switching valve is as follows:
Figure BDA0003567852110000063
Figure BDA0003567852110000064
Figure BDA0003567852110000065
wherein M is the mass of a rodless cylinder piston and the load carried by the rodless cylinder piston, and is actually 1kg; x is cylinder displacement; p is p a 、p b The gas pressure in the A, B chambers; s is S a Is the piston area of the A cavity, S b The piston area of the cavity B; s is S a And S is b Equal area of 2.12 x 10 -4 m 2 ；F f Is the friction force applied to the rodless cylinder; f is other unmodeled dynamics due to hypothesis neglect and external disturbance; k is an air insulation index of 1.4; r is an ideal gas constant of 287.1J/(kg.K); t (T) s The temperature of the air source is 293K; l is the length of the cylinder and is 0.1m; q ma 、q mb The mass flow rate of the gas flowing into the A cavity and the B cavity is respectively F c Coulomb friction force for the cylinder; c is the viscous drag coefficient of the cylinder, 62 N.s/m; f (F) s Representing the maximum static friction of the cylinder.
Let x 1 ＝x，
Figure BDA0003567852110000066
y＝x 1 Change (6)In the form of a state space, i.e. equation (7):
Figure BDA0003567852110000067
wherein u is a control amount,
Figure BDA0003567852110000068
b, as the total disturbance of the system 0 Is a system gain estimate.
Figure BDA0003567852110000071
Figure BDA0003567852110000072
Step 8, designing a three-order active disturbance rejection controller of a five-mode switching strategy according to the state space equation (7) and the control strategy table 1 of the five-mode switching strategy:
Figure BDA0003567852110000073
/>
Figure BDA0003567852110000074
wherein v is 0 For a given position reference signal, v 1 V is 0 V 2 V is 1 V of the differential signal of (v) 3 V is 2 R is the speed factor of the tracking differentiator; y is the system output, z 1 ，z 2 ，z 3 Z is the observed value of the system state 4 Is the observed value of the total disturbance of the system, beta 1 ，β 2 ，β 3 ，β 4 B for the extended state observer parameters 0 Estimating a system gain; k (k) 1 ，k 2 ，k 3 Is nonlinear inverseFeed control law parameters, a 1 ，a 2 ，a 3 Delta is a nonlinear fal function parameter; e, e 0 For displacement error, u is the control amount of the position voltage of the five-mode switching cylinder, and epsilon-mode switching threshold is set to be 0.1mm.
In the implementation process, the controller parameters are as follows:
k 1 ＝1.5，k 2 ＝0.5，k 3 ＝0.2，b 0 ＝2.7，β 1 ＝2.5，β 2 ＝12，β 3 ＝1.1，β 4 ＝0.8，a 1 ＝0.5，a 2 ＝0.25，a 3 ＝0.125，ε＝0.1。
the specific experiment shows that the overshoot is 0mm when tracking a step signal of 30mm, and the steady-state error is 0.05mm, as shown in FIG. 4; the maximum error is 1.2mm when the sinusoidal curve with no load is used for tracking the sinusoidal curve with the frequency of 0.5Hz, the average error is 0.58mm, and the root mean square error is 0.96mm; the maximum error is 4.0mm when the sinusoidal curve of 1Hz is tracked without load, the average error is 1.96mm, and the root mean square error is 2.23mm; the maximum error is 1.6mm when the load is 1kg and the sinusoidal curve with the frequency of 0.5Hz is tracked, the average error is 0.75mm, and the root mean square error is 1.12mm; the maximum error of the sinusoidal curve with the load of 1kg and tracking of 1Hz is 4.9mm, the average error is 2.36mm, the root mean square error is 3.12mm, and the quality of the conventional PID control is compared with that of the conventional PID control as shown in Table 2.
Table 2 control quality comparison
Figure BDA0003567852110000081
And step 9, outputting the control quantity u obtained according to the formula (10) in step 8 to a signal input end of a corresponding high-speed switch valve through a DO port of a controller, and acting on a high-speed switch valve cylinder position system to realize quick and accurate positioning of the cylinder position. Compared with the traditional PID control mode, the method has the advantages that the response speed of cylinder position control and the cylinder position positioning precision are obviously improved, the gas loss is reduced, and the energy is saved.
The foregoing detailed description has set forth the objects, aspects and advantages of the invention in further detail, it should be understood that the foregoing description is only illustrative of the invention and is not intended to limit the scope of the invention, but is to be accorded the full scope of the invention as defined by the appended claims.

Claims (2)

1. The cylinder position control method based on the five-mode switching of the high-speed switch valve is characterized by comprising the following steps of: the cylinder position servo system based on the high-speed switch valve full-bridge loop is controlled to realize high-efficiency and accurate control on the cylinder position positioning;
step one, calculating a displacement error e of a cylinder piston 0 And preset a threshold value epsilon, when |e 0 When the I is less than or equal to epsilon, the system enters a full-closed mode, so that frequent switching of a high-speed switch valve is avoided, and meanwhile, the consumption of gas is saved;
step two, when |e 0 When the I > epsilon, the displacement errors e are calculated respectively 0 And rate of change of displacement error
Figure FDA0004017947180000016
The membership functions Ue, uec of the fast and slow segments are calculated again f And delta s ；
Figure FDA0004017947180000011
Figure FDA0004017947180000012
Wherein a represents a displacement error e 0 B represents the rate of change of displacement error
Figure FDA0004017947180000013
Is defined by the range of (2);
δ f ＝U e ·U ec ，δ s ＝1-δ f (3)
step three, when the displacement error e 0 ＞εTime and delta r ＜δ s The air inlet valve A and the air outlet valve B are controlled by PWM signals, the duty ratio of the two paths of PWM signals is u, and the air inlet valve B and the air outlet valve A are completely closed, at the moment, the cavity A of the rodless cylinder is in air and the cavity B is out of air, so that the piston of the cylinder moves rightwards slowly;
step four, when the displacement error e 0 With < -epsilon and delta f ＜δ s The air inlet valve B and the air outlet valve A are controlled by PWM signals, the duty ratio of the two paths of PWM signals is u, and the air inlet valve A and the air outlet valve B are completely closed, at the moment, the cavity of the rodless cylinder B is filled with air and the cavity A is exhausted, so that the piston of the cylinder moves leftwards slowly;
step five, when e 0 > ε and δ f ≥δ s The air inlet valve A and the air outlet valve B are completely opened, the air inlet valve B and the air outlet valve A are completely closed, and at the moment, the cavity A of the rodless cylinder is filled with air and the cavity B is exhausted, so that the piston of the cylinder moves rightwards rapidly;
step six, when e 0 < -epsilon and delta f ≥δ s The air inlet valve B and the air outlet valve A are completely opened, the air inlet valve A and the air outlet valve B are completely closed, and at the moment, the cavity B of the rodless cylinder is filled with air and the cavity A is exhausted, so that the piston of the cylinder moves leftwards rapidly;
and step seven, a model of a cylinder position servo control system of the high-speed switching valve is as follows:
Figure FDA0004017947180000014
Figure FDA0004017947180000015
Figure FDA0004017947180000021
wherein M is the mass of a rodless cylinder piston and a load carried by the rodless cylinder piston; x is cylinder displacement; p is p a 、p b The gas pressure in the A, B chambers; s is S a Is the piston area of the A cavity, S b The piston area of the cavity B; s is S a And S is b The areas are equal; f (F) f Is the friction force applied to the rodless cylinder; f is other unmodeled dynamics and external disturbances; k is the air insulation index; r is an ideal gas constant; t (T) s Is the temperature of the air source; l is the length of the cylinder; q ma 、q mb The mass flow rate of the gas flowing into the A cavity and the B cavity is respectively F c Coulomb friction force for the cylinder; c is the viscous drag coefficient of the cylinder; f (F) s Representing the maximum static friction of the cylinder;
let x 1 ＝x，
Figure FDA0004017947180000022
y＝x 1 Changing the formula (6) into a form of a state space, namely, the formula (7): />
Figure FDA0004017947180000023
Wherein u is a control amount,
Figure FDA0004017947180000024
b, as the total disturbance of the system 0 Estimating a system gain;
Figure FDA0004017947180000025
Figure FDA0004017947180000026
step eight, designing a third-order active disturbance rejection controller of a system five-mode switching strategy according to the formula (7) and the steps one to six:
Figure FDA0004017947180000027
Figure FDA0004017947180000031
wherein v is 0 For a given position reference signal, v 1 V is 0 V 2 V is 1 V of the differential signal of (v) 3 V is 2 R is the speed factor of the tracking differentiator; y is the system output, z 1 ，z 2 ，z 3 Z is the observed value of the system state 4 Is the observed value of the total disturbance of the system, beta 1 ，β 2 ，β 3 ，β 4 B for the extended state observer parameters 0 Estimating a system gain; k (k) 1 ，k 2 ，k 3 Is a nonlinear feedback control law parameter, a 1 ，a 2 ，a 3 Delta is a nonlinear fal function parameter; e, e 0 For displacement error, u is the voltage control quantity of the position of the cylinder switched in five modes, and epsilon is a preset threshold value; u (u) max Is the maximum voltage control quantity; e is an error parameter in the fal nonlinear function; alpha is a parameter in a fal nonlinear function;
step nine, outputting the control quantity u obtained according to the formula (10) in the step eight to a signal input end of a corresponding high-speed switch valve through a DO port of a controller, and acting on a high-speed switch valve cylinder position system to realize rapid and accurate positioning of a cylinder position; the response speed of the cylinder position control and the cylinder position positioning precision can be obviously improved, the gas loss is reduced, and the energy is saved.
2. The method of claim 1, wherein: the system comprises: the device comprises an air source, a rodless cylinder, two air inlet valves, two exhaust valves, a displacement sensor and a controller;
the air inlets of the air inlet valve A and the air inlet valve B are connected with an air source, the air outlet of the air inlet valve A is connected with the cylinder accommodating cavity A, and the air outlet of the air inlet valve B is connected with the cylinder accommodating cavity B;
the air inlet of the exhaust valve A is connected with the cylinder accommodating cavity A, the air inlet of the exhaust valve B is connected with the cylinder accommodating cavity B, and the air outlets of the exhaust valve A and the exhaust valve B are communicated with the atmosphere;
the displacement sensor is arranged on the rodless cylinder, and the displacement sensor measures the position of the piston in the controlled cylinder and feeds back the position to the controller;
the four-way PWM signal output ends of the controller are connected with the signal input ends of the air inlet valve A, the air inlet valve B, the air outlet valve A and the air outlet valve B;
the controller is used for controlling the displacement error e 0 And the preset threshold epsilon controls the working states of the four valves to be divided into five different working modes of quick rightward movement, slow rightward movement, quick leftward movement, slow leftward movement and complete closing of the cylinder piston.
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