JP3626220B2 - Pneumatic cylinder stop control device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a pneumatic cylinder stop control device for stopping a pneumatic cylinder that repeatedly operates at a specified position by predictive control and learning control.
[0002]
[Prior art]
In a conventionally known pneumatic cylinder stop control device, the position of a piston rod is detected by a position sensor through a peripheral interface adapter (PIA), an A / D converter, for example, every 1 msec, Position information is input to the control device, and the control device calculates the error between the position information of the piston rod and the stop setting position, and determines the control amount of the proportional control valve (drive valve) based on the calculation result. The movement of the piston rod is controlled by controlling the valve opening area of the proportional control valve. Similarly, the control amount of the control valve (brake valve) is determined by the calculation result, and the control valve is opened and closed via the servo amplifier. Control and stop of piston rod positioning by operating the piston rod brake mechanism (lock-up mechanism) I had done.
[0003]
In this case, since it is difficult to predict the friction and load acting on the pneumatic cylinder at the time of starting, there is a possibility that the piston rod of the pneumatic cylinder passes through the designated position and causes a trouble.
In order to prevent troubles caused by passing through the designated position, at the first operation, the piston rod is temporarily stopped by operating the brake mechanism just before a predetermined distance of the designated position, for example, about 2 mm, and the second and subsequent times. In the operation of, based on the result of the actual stop position and the position where the brake mechanism was operated at the time of the first operation, the position where the brake mechanism is operated is corrected so that the stop position matches the specified position, and further learning control is performed. To improve the accuracy of the stop position (see Japanese Utility Model Publication No. 3-41124).
[0004]
[Problems to be solved by the invention]
In the conventional pneumatic cylinder stop control device, as described above, the piston rod is temporarily stopped about 2 mm before the designated position at the time of starting. However, since the speed of the piston rod when operating the brake mechanism differs depending on the designated position to be stopped, there is a considerable error between the designated position and the actual stop position, so that the learning control after the second time is normal. There was a problem that it took a considerable amount of time to be performed.
It is an object of the present invention to perform predictive control at the time of starting to reduce an error between a specified position at the time of starting and an actual stop position, thereby facilitating learning control of the second and subsequent operations.
[0005]
[Means for Solving the Problems]
According to the present invention, the pneumatic cylinder includes a brake mechanism that brakes the piston rod, and a position sensor that detects the position of the piston rod, and the drive valve that outputs compressed air corresponding to an electric signal output from the control device. In a pneumatic cylinder stop control device that controls the movement of the piston rod to stop at a specified position, the first specified position stop operation is controlled by predictive control, and the second and subsequent specified position stop operations are controlled by learning control. The predictive control is divided into two or more areas according to the designated distance to which the piston rod should move. In the first area, the brake mechanism is operated in front of the designated position by a predetermined distance. in the speed data table showing the relationship between the size and the movement distance required to stop the loading of the moving speed and the piston rod of the piston rod Prepared to detect the moving speed before the specified position by a predetermined distance, obtains a moving distance from the moving speed and load by using the velocity data table, to operate the brake mechanism in front by the movement distance from a specified position This is a technical measure.
[0006]
[Action]
In the pneumatic cylinder stop control device of the present invention, when the first designated position stop operation is controlled by predictive control, and the designated position stop operation after the second time is controlled by learning control, this predictive control is performed by moving the piston rod. It is divided into two or more areas according to the designated distance. In the first area, the brake mechanism is operated a predetermined distance before the designated position. In each area after the second area, the speed of the piston rod and the stop movement distance are Using the data for which the relationship is determined, the brake mechanism is operated before the designated position by the distance obtained from this data.
In this way, the error between the designated position at the start and the actual stop position can be reduced, and the second and subsequent learning controls can be easily performed.
[0007]
【Example】
Examples of the present invention will be described below.
FIG. 1 shows an air cylinder and pneumatic circuit diagram of an embodiment of the present invention.
In FIG. 1, reference numeral 1 is a pneumatic cylinder, 2 is a brake mechanism, 3 is a piston rod, 4 is a position sensor, 5 ₁ , 5 ₂ , and 5 ₃ are pressure regulating valves, 6 is a drive valve at 5 port 3 position, 7 is 3 port 2 position brake valve, 8 is a controller, 9 is an air pressure source.
[0008]
An air cylinder and a pneumatic circuit according to an embodiment of the present invention will be described with reference to FIG.
Compressed air, through a pressure regulating valve 5 _1, 5 ₂ from an air pressure source 9 is controlled direction flows into the head side or the rod side of the pneumatic cylinder 1 by the driving valve 6 of 5-port 3-position, the pneumatic cylinder 1 The piston rod 3 moves forward or backward. Braking mechanism 2 is arranged in the pneumatic cylinder 1, the street compressed air pressure regulating valve ₃ from the air pressure source 9, 3 when being controlled by the brake valve 7 of port 2 position flows to the brake mechanism 2 brake mechanism The piston rod 3 is stopped by operating. A position sensor 4 is disposed opposite to the piston rod 3, and an output signal from the position sensor 4 is input to the controller 8. The drive valve 6 and the brake valve 7 are controlled by signals from the controller 8.
[0009]
FIG. 2 is a flowchart of the controller software according to the embodiment of the present invention.
In the communication process of this flowchart, the communication process is performed until the controller starts up. Specifically, the main CPU confirms the setting conditions such as the dip switch, transfers the information to the sub CPU, and transfers the transferred information to the sub CPU. Processing is performed by the CPU, and a display command is output to the display unit (LCD, LED).
[0010]
More specifically, the dip switches are all set to OFF at the initial stage of the controller (the factory state). 1 is for setting the presence or absence of an origin limit. When set to OFF, when no pulse is input to the controller for 0.8 seconds, it is determined that the cylinder is stopped, and that is the origin (display: 0.0). When set to ON, it is determined that the pulse is not input for 0.8 seconds and that the origin is set when a switch (such as an auto switch) attached to the origin is turned on. The switch signal is the No. of the controller INPUT terminal. Connect to 10 (origin input).
[0011]
Dip switch No. Reference numeral 2 designates a brake logic changeover switch, which is a brake valve logic changeover switch. Either the locked state is set when the brake valve output (BR) of the controller is ON or the locked state is set when OFF.
[0012]
Dip switch No. 3 is used to set the count direction switching (set by setting the origin). When OFF is set, the cylinder outlet side is positively counted, and when ON is set, the cylinder return side is positively counted.
[0013]
Dip switch No. 4 is a memory clear setting, and all data stored in the controller is erased. Set to ON and clear the memory by power-on or reset.
[0014]
In the [Received data check] of this flowchart, it is checked whether an error or abnormality has occurred in data transfer from the main CPU to the sub CPU and further from the sub CPU to the display performed in the communication process.
[0015]
In [Key switch processing], the sub CPU performs the capture processing of the signals of the key sheet buttons (UP, DOWN, etc.) attached to the controller.
[0016]
In the [mode switching processing] of this flowchart, the key switch attached to the controller can be switched from the preset mode to the program mode and further to the RUN mode by using the attached key, and the switching signal is transmitted to the sub CPU. Then, a process for switching to each mode display is performed.
[0017]
In each preset mode, initial data is input / processed in the preset mode, positioning data is input / processed in the program mode, control is started in the RUN mode, and a signal sent from the sequencer (PC) is sent. Perform the process. This RUN mode is the main part of the present invention and performs predictive control and learning control of the pneumatic cylinder.
[0018]
FIG. 3 is a flowchart of predictive control and learning control of the pneumatic cylinder according to the embodiment of the present invention.
The operation of the pneumatic cylinder control apparatus according to the embodiment of the present invention will be described with reference to this flowchart.
This pneumatic cylinder control device is suitable for the case where the pneumatic cylinder 1 (see FIG. 1 and the following symbols are the same) is repeatedly stopped at the same position at the designated position, and the first designated position stop operation of the piston rod is performed by predictive control. The operation is stopped at the designated position, and the second and subsequent designated position stopping operations are stopped at the designated position by learning control.
[0019]
When it is started, the presence / absence of learning data is determined, but if there is no learning data in the first operation, [no learning data? ] Is determined as YES, the process proceeds to predictive control, and if there is learning data in the second and subsequent operations, [no learning data? ] Is determined as NO, and the process proceeds to learning control.
[0020]
As shown in FIG. 3, in this predictive control, the specified distance-to be movement of the piston rod 3, a second region of the first region ▲ 1 ▼ from S ₁ to S _2, from S ₂ to S ₃ It is divided into three areas (2) and a third area ( ₃ ) exceeding S3.
Here, the reason for dividing by the designated distance to be moved is that the moving speed and acceleration of the piston rod 3 change depending on the moving distance of the piston rod 3, and the time from when the brake mechanism 2 is operated until the piston rod 3 stops. This is because they are different.
[0021]
The first region {circle around ( ₁ )} has a short moving distance (S _{1 to} S ₂ ), is an initial stage of acceleration of the piston rod 3, and the moving speed width of the piston rod 3 is not wide, so the piston rod 3 should be stopped. The brake valve 7 is operated at a position before L ₁ from the specified position to operate the brake mechanism 2 and stop the piston rod 3.
For example, when it is desired to stop at a specified position with a moving distance of 50 mm, the current position is confirmed based on information from the position sensor 4 and the brake mechanism 2 is operated at a position 48 mm before 2 mm from the specified position. As described above, since the brake mechanism 2 is operated at a position a predetermined distance before the designated position, the software is simplified.
[0022]
The second region {circle around ( ₂ )} has a moving distance of (S _{2 to} S ₃ ) and is in the middle / late stage of acceleration of the piston rod 3, and the moving speed width of the piston rod 3 compared to the first region {circle around (1)}. Therefore, the moving distance required to stop the brake mechanism 2 after the operation varies considerably depending on the magnitude of the moving speed.
Therefore, a relationship between the moving speed of the piston rod 3 and the magnitude of the load acting on the piston rod 3 and the moving distance required for stopping is obtained by experiments, and a speed data table representing the relationship between the speed and the moving distance in consideration of the load is provided. Created and stored in the memory of the controller 8.
[0023]
Then, to detect the moving speed of the piston rod 3 by L ₂ position before than the specified distance, the data selected from the moving speed and load which is detected by the speed data table and position to actuate the brake mechanism 2, The brake mechanism 2 is operated at that position.
For example, when it is desired to stop at a specified position with a moving distance of 80 mm, the current position is confirmed from information from the position sensor 4, and when the position is 40 mm before the specified position (when the moving distance is 40 mm), the piston rod 3 The moving speed is detected, and the data obtained using the speed data table is set as a position where the brake mechanism 2 is to be operated, and the brake mechanism 2 is operated and stopped at that position.
[0024]
The third region ( ₃₎ is a region where the moving distance exceeds S3, and the piston rod 3 is moving at a constant speed, so the speed at the time of detection is the same as in the second region (2). Even in this case, the moving distance required for stopping the piston rod 3 is different from that in the second region (2).
Therefore, another speed data slightly different from that in the second area (2) is created, stored in the memory of the controller 8, and operated in the same manner as in the second area (2).
As described above, the first positioning operation having no learning value is controlled, and the data obtained at this time is stored as learning data.
[0025]
The second and subsequent operations are controlled by learning control, and the current brake data is corrected by the error generated when the piston rod 3 is positioned to obtain the next brake data.
The reason for this correction is that the stop position is shifted due to the influence of wear or the like due to the use of the pneumatic cylinder 1.
[0026]
Learning control will be described.
As described above, when the RUN mode is started, if the operation is performed for the second time or later and there is learning data, [no learning data? ] Is determined as NO, the data is set by [learning brake data set], and the process proceeds to learning control.
[0027]
However, the operation is the first operation and there is no learning data. ] Is determined as YES, according to the first area (1) for short distance, the second area (2) for medium distance, and the third area (3) for long distance by predictive control as described above. The distance between the designated position with high accuracy and the position where the brake mechanism is operated is determined.
The distance between this highly accurate designated position and the position for operating the brake mechanism 2 is input, and the second and subsequent movements of the piston rod 3 and the designated position stop operation are started by learning control.
[0028]
During the second and subsequent operations of the piston rod 3, a time interval for checking the position from when the piston rod 3 is stopped to when it is actually stopped is set (stop check timer setting).
[0029]
In order to check the position from the stop control of the piston rod 3 to the actual stop, when the piston rod 3 stops (operation completed (stop)? YES), the learning data is updated according to the result (learning) Data update).
The update in this case means that the position at which the next brake mechanism 2 is operated is corrected based on the distance (error) from the set position generated in the previous operation to the actually stopped position.
[0030]
If the position stop error does not fall within the set range even after the previous learning data is updated (position stop error ≤ set range? NO), check the position from the stop control of the piston rod 3 to the actual stop again. The learning data is updated according to the result (retry process).
These results are displayed on the display (position display) and main processing (main processing) is performed.
[0031]
When the piston rod 3 is not stopped (operation completion (stop)? NO), the result is displayed on the display (position display) and main processing is performed (main processing).
[0032]
If the position stop error is within the set range even after the previous learning data is updated (position stop error ≦ set range? YES), the next stop position is set (next position set).
[0033]
In this example, satisfactory results were obtained when S ₁ = 5 mm, S ₂ = 65 mm, S ₃ = 100 mm, L ₁ = 2 mm, and L ₂ = 40 mm.
[0034]
【The invention's effect】
According to the present invention, the first designated position control operation of the pneumatic cylinder stop control is performed by high-precision predictive control divided into a plurality of speed regions , and the second and subsequent designated position control operations are performed based on the data. Therefore, the shift to the learning control is smoothly performed, and the stop control of the pneumatic cylinder can be performed with high accuracy and speed.
Further, the predictive control is divided into two or more areas according to the designated distance to which the piston rod should move. In the first area, the brake mechanism is operated in front of the designated position by a predetermined distance. In each area, a speed data table showing the relationship between the moving speed of the piston rod and the magnitude of the load on the piston rod and the moving distance required for stopping is prepared, and the moving speed is detected before the specified position by a predetermined distance. Then, the moving distance is obtained from the moving speed and the load using the speed data table, and the brake mechanism is operated just before the moving distance from the designated position. As described above, when the designated distance to be moved is short, it is easily performed by controlling the first area. When the moving distance is not short, the control is performed by the control after the second region, and the moving distance is obtained using a speed data table prepared in advance, so that highly accurate control is realized.
[Brief description of the drawings]
FIG. 1 is a diagram of an air cylinder and a pneumatic circuit according to an embodiment of the present invention.
FIG. 2 is a flowchart of controller software according to the embodiment of this invention.
FIG. 3 is a flowchart of predictive control and learning control of the pneumatic cylinder according to the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pneumatic cylinder 2 Brake mechanism 3 Piston rod 4 Position sensor 5 ₁ , 5 ₂ , 5 ₃ Pressure adjustment valve 6 5 port 3 position drive valve 7 3 port 2 position brake valve 8 Controller 9 Air pressure source

Claims (1)

The pneumatic cylinder includes a brake mechanism that brakes the piston rod and a position sensor that detects the position of the piston rod, and the piston rod is moved by a drive valve that outputs compressed air corresponding to an electric signal output from the control device. In the pneumatic cylinder stop control device for controlling the engine to stop at the specified position, the first specified position stop operation is controlled by the predictive control, and the second and subsequent specified position stop operations are controlled by the learning control. The piston rod is divided into two or more areas according to the designated distance to which the piston rod should move. In the first area, the brake mechanism is operated before the designated position by a predetermined distance. In each area after the second area, the piston rod is operated. Prepare a speed data table that shows the relationship between the travel speed and piston rod load and the travel distance required for stopping, Detecting the front at the moving speed of only the specified position a distance defined order, obtains a moving distance from the moving speed and load by using the velocity data table, characterized in that actuating the brake mechanism in front by the movement distance from a specified position A pneumatic cylinder stop control device.

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