CN111521322B - Electro-hydraulic servo equipment for force standard machine and control method thereof - Google Patents
Electro-hydraulic servo equipment for force standard machine and control method thereof Download PDFInfo
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- CN111521322B CN111521322B CN202010493133.2A CN202010493133A CN111521322B CN 111521322 B CN111521322 B CN 111521322B CN 202010493133 A CN202010493133 A CN 202010493133A CN 111521322 B CN111521322 B CN 111521322B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L25/00—Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B15/00—Systems controlled by a computer
- G05B15/02—Systems controlled by a computer electric
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D15/00—Control of mechanical force or stress; Control of mechanical pressure
- G05D15/01—Control of mechanical force or stress; Control of mechanical pressure characterised by the use of electric means
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P5/00—Arrangements specially adapted for regulating or controlling the speed or torque of two or more electric motors
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Abstract
The invention discloses an electro-hydraulic servo device for a force standard machine and a control method thereof, wherein the electro-hydraulic servo device comprises: the system comprises a computer, a control box, a standard dynamometer, a measured dynamometer, a standard sensor, a measured sensor, a main frame, an oil cylinder, a digital throttle valve, a superposition overflow valve, a servo motor driver, a miniature gear pump and an oil filter. The built-in stepping motor of the digital throttle valve receives an instruction from the control box to automatically adjust the size of the throttle orifice, so that the high-precision throttling effect and the oil return function in the servo control process of the force standard machine are realized. The digital throttle valve is connected with the oil cylinder and the oil tank through the overlapped overflow valve. The control box is communicated with the computer through Ethernet connection, and receives and executes instructions of a computer program. The device is connected with a tested instrument through a serial port for communication, and force value data collected by the tested instrument is received in real time and fed back to the computer. And the control box has the function of simultaneously coordinating and controlling one path of servo motor and one path of stepping motor. The invention realizes the electro-hydraulic servo control for the force standard machine, the whole computer is automatically controlled, the hydraulic system has simple structure, no high-pressure reversing valve is needed, the system has high loading speed, can quickly enter the load holding state, has stable load holding state without overshoot, can meet the verification precision requirement of one ten thousandth of the force standard machine and improves the verification operation efficiency.
Description
Technical Field
The invention relates to electro-hydraulic servo equipment for a force standard machine, in particular to control equipment and a control method for a sensor comparison machine, and belongs to the field of mechanical measurement.
Background
The force standard machine is used as a precision instrument and is a basic core technology in the aspect of industrial metering. On one hand, the force standard machine has high requirement on load-holding precision, and usually needs to reach the level of one ten-thousandth, so that the realization technical difficulty is high, and the technical difficulty which needs to be solved urgently at home and abroad is always. On the other hand, the force standard machine relates to the working efficiency of metering calibration, how to load the force to a metering point at the maximum speed without overshoot of the force value, and the force standard machine can stably hold the load within the control precision requirement in the shortest time, and is a core technical point of important attention in the industry.
Currently, there are two main development directions in the field of force standard machines: (1) the superposed weight static load standard machine has accurate precision, but relates to high-tonnage equipment, and the equipment device is very large and has high manufacturing cost; (2) the electro-hydraulic servo control technology is applied to realize loading and load holding control, the system flexibility is strong, but the requirements on a hydraulic system and a control algorithm are high.
Disclosure of Invention
The invention aims to realize an electro-hydraulic servo system for a force standard machine, which has the advantages of simple structure, quick loading, quick and stable load holding and high control precision. The calibration process of the force standard machine is controlled automatically by a computer program, the control box receives instructions from the computer and controls the rotating speed of the servo motor and the position of the valve port of the digital throttle valve in real time, and meanwhile, the control box collects the value of the force value from the standard dynamometer and feeds the value back to the computer in real time.
The adopted technical scheme is as follows: the system consists of a computer 1, a control box 2, a standard dynamometer 3, a measured dynamometer 4, a standard sensor 5, a measured sensor 6, a main frame 7, an oil cylinder 8, a digital throttle valve 9, a superposed overflow valve 10, a servo motor 11, a servo motor driver 12, a miniature gear pump 13 and an oil filter 14; the built-in stepping motor of the digital throttle valve receives an instruction from the control box to automatically adjust the size of the throttle orifice, so that the high-precision throttling effect and the oil return function in the servo control process of the force standard machine are realized. The digital throttle valve is connected with the oil cylinder and the oil tank through the overlapped overflow valve. The control box is communicated with the computer through Ethernet connection, and receives and executes instructions of a computer program. The device is connected with a tested instrument through a serial port for communication, and force value data collected by the tested instrument is received in real time and fed back to the computer. And the control box has the function of simultaneously coordinating and controlling one path of servo motor and one path of stepping motor. The miniature gear pump is driven by a servo motor, and hydraulic oil is controlled to flow to the oil cylinder piston through a pipeline so as to apply pressure to the standard sensor and the measured sensor, so that high-precision load-holding control of the force standard machine is realized. Control box built-in have control mainboard, transformer, step motor driver, the control mainboard includes: the main control chip circuit, power supply circuit, Ethernet communication circuit, serial port communication circuit, servo motor drive circuit, step motor drive circuit.
Compared with the background technology, the method has the beneficial effects that: a frequency converter and a high-pressure reversing valve are not needed, and the hydraulic system is simple in structure; the system is stable in high-pressure loading and load holding, and high in force value precision; the whole process is automatically controlled by a computer, the maximum loading pressure is high, and the device has the composite functions of loading, load holding, reversing and the like.
A second object of the invention is to develop an optimized control method that is adapted to the electrohydraulic servo system for force standard machines.
The adopted specific technical scheme comprises the following control steps:
(1) initializing, after the system is electrified and self-checked, sending an instruction to a control box by a computer program according to a preset design to control and adjust the position of a valve port of the digital throttle valve to a certain specified initial state;
(2) the computer program sends an instruction to the control box according to a preset design to control the servo motor to operate to a certain specified rotating speed so as to realize the movement of the oil cylinder piston;
(3) loading, namely when an oil cylinder piston is in contact with a standard sensor and a measured sensor, automatically switching to enter a closed-loop force loading stage after a loading force reaches an inlet force;
(4) the control box carries out closed-loop PID calculation on the demand force rate and the actual force rate calculated by the feedback of the standard dynamometer and controls and adjusts the output quantity of the rotating speed of the servo motor in real time;
(5) in the load holding process, when the force value reaches a preset load holding target value in a computer program, entering a force load holding stage and starting a load holding timer, the control box performs closed-loop PID calculation on the required force value and an actual force value fed back by a standard dynamometer and controls and adjusts the rotating speed output quantity of the servo motor in real time;
(6) repeatedly executing the step (4) and the step (5) according to a flow preset by a computer program until the verification and comparison of all the force value points required by the preset are completed;
(7) and finishing control, and sending an instruction to the control box by the computer program according to a preset design to respectively control the servo motor and the stepping motor to reach the zero rotating speed and the throttle reset position.
By applying the control method, the system can be loaded fast, quickly enters load holding, is stable in load holding and does not overshoot, the calibration precision requirement of one ten thousandth of a force standard machine can be met, and the calibration operation efficiency is improved.
Drawings
FIG. 1 is a schematic diagram of a hydraulic system of the present invention
FIG. 2 is a flow chart of a force versus test process using one embodiment of the present invention
In the figure: 1. the system comprises a computer, 2, a control box, 3, a standard dynamometer, 4, a measured dynamometer, 5, a standard sensor, 6, a measured sensor, 7, a main frame, 8, an oil cylinder, 9, a digital throttle valve, 10, a superposition overflow valve, 11, a servo motor, 12, a servo motor driver, 13, a micro gear pump, 14 and an oil filter
Detailed Description
The invention will be further explained with reference to the drawings.
As shown in fig. 1, an electro-hydraulic servo measurement and control system for a force standard machine is composed of a computer 1, a control box 2, a standard dynamometer 3, a measured dynamometer 4, a standard sensor 5, a measured sensor 6, a main frame 7, an oil cylinder 8, a digital throttle valve 9, a superposed overflow valve 10, a servo motor 11, a servo motor driver 12, a miniature gear pump 13 and an oil filter 14; the computer 1 is connected with the control box 2 through Ethernet; the control box 2 is connected with the standard dynamometer 3 and the tested dynamometer 4 and is connected with the digital throttle valve 9 and the servo motor driver 12; the digital throttle valve 9 is respectively connected with the oil cylinder 8 and the oil tank (through an oil filter 14) through a superposition type overflow valve 10; the servo motor driver 12 is connected with the servo motor 11 and the micro gear pump 13 in sequence.
The working process of the invention is as follows:
as shown in fig. 2, a force versus assay process flow using one embodiment of the present invention is as follows: and placing the standard sensor and the sensor to be detected at the appointed position of the main frame oil cylinder piston, connecting the standard dynamometer and the dynamometer to be detected, and completing the early preparation work of force comparison operation. And (3) turning on a power supply of an oil pump motor, starting a control box and a computer, starting self-checking by computer measurement and control software and the control box, and preparing to enter the automatic power comparison process operation after the self-checking is passed.
Firstly, entering a first stage control, namely an open-loop control stage, sending a digital throttle valve port instruction by a computer, adjusting the valve port instruction to a set position by a stepping motor according to the valve port instruction, and keeping the position of the throttle valve port to be controlled to a preset throttle port position. The computer sends out the open-loop rotating speed instruction of the servo motor at the stage after the throttle valve fed back by the control box reaches the set valve port position, the pressure is not subjected to closed-loop control at the stage, the control box feeds back the collected force value signal from the standard dynamometer to the computer in real time, and the computer displays the force value signal on a software interface of the computer in real time.
When the collected force value reaches the inlet force, namely the first pressure value, the open-loop loading stage of the force is completed, and at the moment, the oil cylinder piston is in contact with the standard sensor and the measured sensor. The control box enters a second stage, namely a first force value loading stage according to a preset inlet force value. The phase is a force loading phase, and the force first channel is subjected to closed-loop control. The control box collects the force value from the standard dynamometer in real time, does not filter the force value signal, converts the force value signal into an actual force change rate value and a target force change rate value to perform closed-loop control, and calculates the control instruction value of the servo motor in real time to adjust the rotating speed of the servo motor. The force loading rate can be set, and is generally set by measurement and control software on a computer according to test requirements. The force loading closed-loop control parameters preset in the control box are a key loop for ensuring the force loading performance, and the loading force value rate is adjusted in real time through a pressure regulating system consisting of a servo motor, a miniature gear pump and a digital throttle valve.
When the difference between the collected force value signal and the first load-holding value target is less than a preset load buffering time, the first force value loading stage is indicated to enter a first force value loading buffering period. This stage is the end of the first force value loading stage, which reduces the actual force loading rate to the system minimum control rate by rapidly reducing the target loading rate. Through the operation of the buffer period, the loading speed is mainly reduced to the minimum speed as soon as possible, so that the system can stably enter a load-holding stage and the force value is ensured not to overshoot to the maximum extent. The preset loading buffer time and the minimum control speed are a pair of control contradictions, and the minimum control speed can be quickly and stably reached within the shortest buffer time through the optimization of the control algorithm, so that the high-efficiency operation efficiency is realized.
When the difference between the collected force value signal and the first load-holding value target is smaller than a preset force value interval, the first force value loading stage is ended, and then the first force value load-holding stage is started. And at the moment, the first force channel is in closed-loop control, the control box acquires the actual force value and the target force value from the standard dynamometer in real time to perform closed-loop control, and the rotating speed value of the servo motor is calculated and issued in real time. The force-bearing load closed-loop control parameters preset in the control box are a key ring for ensuring the high-precision performance of the force-bearing load.
When the first load-holding time reaches a preset time, the next stage is entered, generally, the loading and the load-holding are alternately carried out and are preset in a computer measurement and control software test project. Generally, when the maximum holding force phase is completed, the unloading phase of the hydraulic system is entered when the force ratio is indicated to end the loading process. And in the unloading stage, the control box controls the digital throttle valve to adjust to the position of the return oil valve port for unloading operation.
The foregoing detailed description is intended to illustrate and not limit the invention, which is intended to be within the spirit and scope of the appended claims, and any changes and modifications that fall within the true spirit and scope of the invention are intended to be covered by the following claims.
Claims (4)
1. A control method of an electro-hydraulic servo device for a force standard machine is characterized by comprising the following steps:
(1) initializing, after the system is electrified and self-checked, sending an instruction to a control box by a computer program according to a preset design to control and adjust the position of a valve port of the digital throttle valve to a certain specified initial state;
(2) the computer program sends an instruction to the control box according to a preset design to control the servo motor to operate to a certain specified rotating speed so as to realize the movement of the oil cylinder piston;
(3) loading, namely when an oil cylinder piston is in contact with a standard sensor and a measured sensor, automatically switching to enter a closed-loop force loading stage after a loading force reaches an inlet force; the system automatically finishes the pre-loading for a preset number of times according to the setting of a computer program and then enters the next step;
(4) the control box carries out closed-loop PID calculation on the demand force rate and the actual force rate calculated by the feedback of the standard dynamometer and controls and adjusts the output quantity of the rotating speed of the servo motor in real time;
(5) in the load holding process, when the force value reaches a preset load holding target value in a computer program, entering a force load holding stage and starting a load holding timer, the control box performs closed-loop PID calculation on the required force value and an actual force value fed back by a standard dynamometer and controls and adjusts the rotating speed output quantity of the servo motor in real time;
(6) repeatedly executing the step (4) and the step (5) according to a flow preset by a computer program until the verification and comparison of all the force value points required by the preset are completed;
(7) finishing control, and sending an instruction to the control box by the computer program according to a preset design to respectively control the servo motor and the stepping motor to reach a zero rotating speed and a throttle reset position;
the step (4) further comprises the following steps: the control box updates the PID parameter in real time according to the current actual force value and the loading rate table to control the loading capacity to reach the load-holding target force value in the shortest time; before the load-holding target force value is approached, a loading buffer period is designed, and the force loading rate is made to approach the minimum loading speed of the system in the shortest time by quickly attenuating the required loading rate value.
2. The control method of an electro-hydraulic servo device for a force standard machine according to claim 1, characterized by: the step (5) further comprises the following steps: the control box enters a force and load holding control stage in advance through a preset force value lead, and a PID parameter control system is adjusted according to a current actual force value look-up table in the force and load holding stage so as to meet the high-precision load holding requirement; the preset force value lead parameter is related to the target force value and the loading speed.
3. The control method of an electro-hydraulic servo device for a force standard machine according to claim 1, characterized by: in the step (2) -step (7), the digital throttle valve automatically performs open-loop regulation in real time according to the mode and the control method set by the system, and can enter a closed loop from the open loop at a designated stage, and the servo motor exits the closed-loop control.
4. The control method of an electro-hydraulic servo device for a force standard machine according to claim 1, characterized by: the step (1) -the step (7) is preset by a computer program, and the computer program can set and edit the loading rate, the load-holding target value and the load-holding time.
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| CN202010493133.2A CN111521322B (en) | 2020-06-03 | 2020-06-03 | Electro-hydraulic servo equipment for force standard machine and control method thereof |
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| CN202010493133.2A CN111521322B (en) | 2020-06-03 | 2020-06-03 | Electro-hydraulic servo equipment for force standard machine and control method thereof |
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| CN111521322B true CN111521322B (en) | 2021-08-17 |
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| CN112648245A (en) * | 2020-12-22 | 2021-04-13 | 苏州铁马自动化科技有限公司 | Electro-hydraulic servo equipment for tablet press |
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