JP3370458B2 - Hydraulic servo device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic servo device using, for example, a servo valve.

[0002]

2. Description of the Related Art Conventionally, in a control system in which the relationship between the opening of a valve for controlling the flow rate of a fluid and the flow rate is non-linear, the manipulated variable is expressed by a mathematical expression or a correction table specific to the valve. There is a device that corrects and outputs the data so that the manipulated variable and the flow rate have a linear relationship.

However, in the above control system, even if the characteristic of the valve can be linearly corrected based on the characteristic of the valve itself, in the hydraulic servo device controlled by the hydraulic pressure, the change of the viscosity of the hydraulic oil, There is a problem that the characteristics of the entire system become non-linear due to the length of piping, the characteristics of actuators such as hydraulic cylinders, and the difference in the friction coefficient of the sliding surface of the slide.

Therefore, an object of the present invention is to provide a hydraulic servo system capable of automatically correcting the characteristics of the entire hydraulic servo system so as to be linear.

[0005]

In order to achieve the above object, a hydraulic servo system according to a first aspect of the present invention includes a control amount detecting means for detecting a control amount of a controlled object controlled by hydraulic pressure, and an oil for the controlled object. In a hydraulic servo device including an operation signal output means for outputting an operation signal to a valve for controlling a flow rate, a lamp output command for causing the operation signal output means to output a ramp-shaped operation signal increasing in proportion to time. Means, and the operation signal output based on the characteristic curve of the control amount detected by the control amount detection means with respect to the lamp-shaped operation signal output from the operation signal output means by the lamp output command means. Conversion table creation for creating a conversion table for converting and outputting the operation signal so that the operation signal output from the means and the control amount of the controlled object are approximately proportional Stage and, a conversion table storing means for storing the conversion table created by the conversion table creation means, the operation signal output means varying the
Group to the conversion table stored in the conversion table storing means
By outputting the operation signal converted according to
Te, characteristic of the entire hydraulic servo system is characterized by the this <br/> to be linear.

A hydraulic servo apparatus according to a second aspect is the hydraulic servo apparatus according to the first aspect, in which a division number is set for dividing the range of the controlled variable of the controlled object with respect to the ramp-shaped operation signal. The conversion table creating means includes a number setting means, and creates a conversion table for converting the operation signal for each control amount determined based on the division number set by the division number setting means. I am trying.

[0007]

Before the hydraulic servo system according to the first aspect of the present invention is actually operated, the ramp output command means controls the flow rate of the oil to be controlled from the operation signal output means by a ramp operation signal increasing in proportion to time. The control amount detection means detects the control amount of the controlled object according to the lamp-shaped operation signal from the operation signal output means. Then, based on the characteristic curve of the control amount detected by the control amount detection unit with respect to the lamp-shaped operation signal output from the operation signal output unit, the conversion table creating unit outputs the operation output from the operation signal output unit. A conversion table for converting and outputting the operation signal is created so that the signal and the controlled variable of the controlled object are substantially proportional to each other. The conversion table created by the conversion table creating means is stored in the conversion table storage means. In this way, before actually driving, a conversion table for converting the operation signal for obtaining the control amount into a signal required for actually obtaining the control amount is created and stored in the conversion table storage means. Of. When actually performing automatic control, the operation signal output from the operation signal output means is converted based on the conversion table stored in the conversion table storage means, and the control target is controlled by the converted signal. To do. That is, in the case of controlling an object to be controlled whose relationship between the operation signal and the control amount is non-linear, when the operation signal output means outputs the operation signal to obtain the control amount, the conversion table stored in the conversion table storage means. Based on the above, by outputting the converted operation signal, the nonlinear characteristic of the control amount for the operation signal is corrected to make the characteristic of the entire hydraulic servo system linear.
To do so .

Therefore, in the hydraulic servo device, even if the characteristic of the control amount with respect to the operation signal is non-linear due to the viscosity of oil, the response delay of the valve, the difference in the friction coefficient of the slide surface, etc., the entire hydraulic servo device. The controllability of can be improved.

Further, according to the hydraulic servo apparatus of the second aspect, in the hydraulic servo apparatus of the first aspect, the division number setting means divides the range of the controlled variable of the controlled object with respect to the ramp-shaped operation signal. The conversion table creating means creates a conversion table for converting the operation signal for each control amount determined based on the division number set by the division number setting means. When actually controlling the controlled object, the operation signal output means converts the operation signal based on the correction curve represented by the conversion table stored in the conversion table storage means,
The corrected operation signal is output.

Therefore, it is possible to create a conversion table for each control amount that is appropriately determined according to the variation width (range) of the control amount of the controlled object.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A hydraulic servo device according to the present invention will be described in detail below with reference to an embodiment.

FIG. 1 is a block diagram of a hydraulic servo system according to an embodiment of the present invention. Reference numeral 1 denotes a command voltage signal as an operation signal having a microcomputer (hereinafter referred to as a microcomputer) and an input / output circuit. Controller that outputs
Is a valve driver that receives a command voltage signal from the controller 1 and outputs a spool displacement command signal in accordance with the command voltage. Reference numeral 3 is a spool displacement command signal from the valve driver 2 and a spool (not shown). ) To adjust the oil flow rate, 4 is a hydraulic cylinder in which a piston (not shown) reciprocates according to the flow rate-adjusted oil flow from the servo valve 3, and 5 is the hydraulic cylinder 4 Is a slide mechanically connected to the piston and reciprocates according to the movement of the piston. Reference numeral 6 is an example of a control amount detecting means for detecting the movement amount of the slide 5 and outputting a feedback pulse proportional to the movement amount. As a sensor. The valve driver 2, the servo valve 3, the hydraulic cylinder 4 and the slide 5 constitute a controlled object.

Further, the controller 1 outputs a command voltage signal output section 11 as an operation signal output means for outputting an operation signal and a ramp-shaped command voltage signal increasing to the command voltage signal output section 11 in proportion to time. The command voltage signal is converted based on a lamp output command unit 12 as a lamp output command unit for outputting and a feedback pulse detected by the sensor 6 when the lamp output command unit 12 outputs a ramp-shaped command voltage signal. A conversion table creating unit 13 as a conversion table creating unit for creating a conversion table for performing the conversion table, and a conversion table storage unit 14 as a conversion table storing unit for storing the conversion table created by the conversion table creating unit 13. ing. The controller 1 sets the number of divisions for setting the number of divisions for defining the range of speeds represented by the increase amount of the feedback pulse when the ramp-shaped command voltage signal output from the lamp output command unit 12 is output. The conversion table creation unit 13 converts the ramp-shaped command voltage signal for each speed determined based on the division number set by the division number setting unit 15 and outputs the ramp-shaped command voltage signal. Create a conversion table for.

In the hydraulic servo device having the above structure, the controller 1 controls the speed corresponding to the increase amount of the feedback pulse from the sensor 6 to be a predetermined speed.
The command voltage signal is output to the valve driver 2. At this time, in the servo valve 3, the oil flow rate is adjusted based on the spool displacement command signal from the valve driver 2, but there is a response delay or dead zone to the spool displacement signal. In addition, the oil flow from the servo valve 3 also has delays, piping resistance, and the like. The hydraulic cylinder 4 has packing resistance and the like, and the slide 5 has static friction and dynamic friction. Therefore, the speed characteristic represented by the increase amount of the feedback pulse with respect to the command voltage signal of the hydraulic servo device is non-linear.

Therefore, in order to correct the non-linear characteristic of the hydraulic servo system, the controller 1 is operated before actual operation.
A correction data measurement process for creating a correction conversion table for converting the command voltage signal output from the device and a correction table creation process, which will be described later, are executed. When the automatic control is actually performed, the correction execution flag is turned on after the correction table is created, and the correction execution process for converting and outputting the command voltage signal is performed. The correction execution is processed by interruption every predetermined time. When the correction execution flag is off, data conversion is not performed, and when the correction execution flag is on, data conversion is performed.

The process of measuring the correction data, the process of creating the correction table, and the process of executing the correction of the controller 1 will be described below with reference to the flowcharts of FIGS.

First, in FIG. 2, when the process of measuring the correction data is started, the range to be corrected first, that is, the range of the command code corresponding to the command voltage is set in step S1. The range of the command code to be corrected is
For example, if the command voltage range is 0 to 1 V, the command code is set to 0 to 200.
If the command voltage range is 0 to 2V, the command code is 0 to 400
And Next, in step S2, the output data number S
Is set to 0. That is, the output data number S used to output the lamp voltage that increases in proportion to time is initialized.

Next, in step S3, it is determined whether the output data number S is within the correction range, for example, 0-200.
When it is determined in step S3 that the output data number S is within the correction range, the process proceeds to step S4.

Next, in step S4, (neutral voltage code +
S) is DA (digital / analog) converted and a command voltage signal corresponding to (neutral voltage code + S) is output to the valve driver 2. The neutral voltage code is slide 5
Is a reference code (0) of a ramp-shaped command voltage signal.

Next, in step S5, the current speed, that is, the increase amount of the feedback pulse from the sensor 6 is substituted into the S-th speed data array of the output data number S. Then, in step S6, the output data number S is incremented by 1 and updated.

Thus, steps S3 to S6 are repeated within the correction range of the output data number S to output the ramp-shaped command voltage signal corresponding to the command codes 0-200. Then, the increase amount of the feedback pulse from the sensor 6 corresponding to the current speed for each command voltage is stored in the speed data array, and the output data number S is output in step S3.
If it is determined that is not within the range, the correction data measurement is ended, and then the correction table creation processing is started.

In FIG. 3, when the process of creating the correction table is started, the correction execution flag is turned off in step S11. It should be noted that this correction execution flag is turned on in step S22 described later when the creation of the correction table is completed. Next, in step S12, the speed data array is searched from the beginning, and the array number (corresponding to the output data number) when the array content becomes larger than 0 is substituted for the 0th data in the correction table. The 0th data in this correction table corresponds to the dead zone of the entire system.

Next, in step S13, the number of correction tables N
To set. That is, the correction table number N for setting the range of the speed when the ramp-shaped command voltage signal is output is set. In this embodiment, since the correction range is set to 1/10, the correction table number N is set to 20 if the correction range command code is 0 to 200, and is set to 40 if the correction range command code is 0 to 400. Next, in step S14, the final value in the final position of the speed data array is set to MAX.
Substitute in (criterion for creating correction table). Next, the correction table number K is set to 1 in step S15.

Then, in step S16, it is determined whether the correction table number K is smaller than the correction table number N, and
If it is determined that the correction table number K is smaller than the correction table number N, the process proceeds to step S17, while if it is determined that the correction table number K is equal to or larger than the correction table number N, step S17.
In step 22, the correction execution flag is turned on, and this processing ends.

Next, in step S17, the output data number S
The value of (K−1th correction table value + 1) is substituted into
That is, a value obtained by adding 1 to the value of the correction table immediately before the correction table number K to be created is substituted into the output data number S to obtain the output data number of the search start.

Next, in step S18, it is determined whether or not the S-th speed in the speed data array is MAX × K / N or more,
If it is determined that the S-th speed in the speed data array is MAX × K / N or more, the process proceeds to step S20. If it is determined that the S-th speed in the speed data array is less than MAX × K / N, the process proceeds to step S19. . Then, step S19
The output data number S is incremented by 1 and step S18 is repeated.

Next, in step S20, the output data number S is assigned to the Kth correction table, the process proceeds to step S21, the correction table number K is incremented by 1, and step S16 is performed.
Return to. In this way, the processes from step S16 to step S21 are repeated until the correction table number K becomes equal to or larger than the correction table number N, and the data is substituted into the correction table. When the correction table number K becomes equal to or larger than the number N of correction tables, the correction execution flag is turned on in step S22, and the correction table creation process ends.

Next, in FIG. 4, DATA (= command voltage code-neutral voltage code) is calculated by control voltage calculation in step S31. Next, in step S32, DAT
If it is determined whether A is within the correction range, that is, within the range of the command voltage code 0 to 200, and if it is determined that DATA is within the correction range, the process proceeds to step S33, while if it is determined that DATA is not within the correction range, It proceeds to step S37.

Next, in step S33, it is determined whether or not the correction execution flag is ON, and when the correction execution flag is ON, that is, when the correction table creating process is completed, the process proceeds to step S34 and the data is stored. Do the conversion. That is, DATA is converted into CODE by the correction table. On the other hand, when the correction execution flag is off in step S33, only in step S37, DATA is substituted for CODE, and the process proceeds to step S35.

Next, in step S35, a DA output voltage code is created. That is, COD is added to the above neutral voltage code.
The output voltage code is calculated by adding E. Then, the process proceeds to step S36, the output voltage code is DA converted, and the command voltage signal is output to the valve driver 2.

Thus, when the ramp output command section 12 outputs the ramp-shaped command voltage signal shown in FIG. 5, the speed characteristic represented by the increase amount of the feedback pulse from the sensor 6 with respect to the command voltage (code) is shown in FIG. It becomes non-linear as shown by the curve of No. 6. The above command voltage at this time
(Code) range 0-200, speed range 0-
It will be 20 mm / s. Then, as shown in FIG. 7, the speed range is divided into 20, and command voltages (codes) corresponding to the respective divided speeds are stored in the correction tables [0] to [20]. Therefore, the relationship between the command voltage before correction and the command voltage after correction is the correction curve shown in FIG.

As described above, when the relationship between the command voltage signal and the increase amount of the feedback pulse has a non-linear characteristic, the conversion table storage unit 14 stores the command voltage signal for actual automatic control. Based on the stored conversion table, the command voltage signal output unit 11 outputs the corrected command voltage signal, thereby correcting the non-linear characteristic of the increase amount of the feedback pulse with respect to the command voltage signal, that is, the speed to obtain a substantially linear characteristic. can do.
Therefore, regardless of which main engine is non-linear due to oil viscosity, response delay of valves, etc., difference in friction coefficient of slide surface of slide, etc., conversion table is automatically created before actual operation. Since the command voltage signal converted based on the conversion table is output, the controllability of the entire system can be improved.

Further, since the speed range represented by the increase amount of the feedback pulse with respect to the ramp-shaped command voltage signal is equally divided based on the correction table number N set by the division number setting section 15, the speed change width is It is possible to create a conversion table for each speed that is appropriately determined according to the (range).

In the above embodiment, the valve driver 2, the servo valve 3, the hydraulic cylinder 4 and the slide 5 are used as the controlled object, but the controlled object is not limited to this, and the characteristic of the operation signal and the controlled variable is nonlinear. Any target will do.

Further, in the above embodiment, the division number setting section 15 divides the range of the speed indicated by the increase amount of the feedback pulse with respect to the ramp-shaped command voltage signal into equal parts,
A conversion table was created to convert the command voltage signal for each equally divided speed, but the range of the control amount of the control target for the ramp-shaped operation signal is not limited to equal division, and the control target for the ramp-shaped operation signal is not limited. You may divide so that the conversion table showing the characteristic curve of the control amount of can be created.

In the above embodiment, the command voltage signal output unit 11, the lamp output command unit 12, the conversion table creating unit 13, the conversion table storage unit 14, and the division number setting unit 15 of the controller 1 are the microcomputer and the input / output circuit. However, it goes without saying that a logic circuit and an input / output circuit may be used instead of the microcomputer.

Further, in the above embodiment, the controller 1
Controls the speed represented by the amount of increase in the feedback pulse from the sensor 6, but the controlled variable to be controlled is not limited to the speed, and may be position, pressure, flow rate, or the like.

[0038]

As is apparent from the above, the hydraulic servo system according to the first aspect of the present invention controls the amount of control of the controlled object controlled by hydraulic pressure, and the flow rate of the oil of the controlled object. In a hydraulic servo device having an operation signal output means for outputting an operation signal to a valve to be controlled,
The lamp output command means causes the operation signal output means to output a ramp-shaped operation signal that increases in proportion to time, and the control for the lamp-shaped operation signal output from the operation signal output means by the lamp output command means. Based on the characteristic curve of the control amount detected by the amount detection means, the conversion table creation means converts the operation signal so that the operation signal output from the operation signal output means and the control amount of the controlled object are substantially proportional to each other. Conversion table is created by the conversion table creating means, the conversion table created by the conversion table creating means is stored in the conversion table storing means, and the operation signal outputting means converts the conversion table.
Based on the conversion table stored in the cable storage means.
By outputting the converted operation signal, the hydraulic
The characteristics of the entire servo system are made linear .

Therefore, according to the hydraulic servo system of the first aspect of the present invention, the conversion table is automatically created before the actual operation and is stored in the conversion table storage means when the automatic operation is actually performed. Based on the converted table, the operation signal output means outputs the converted operation signal, whereby the characteristic of the control amount with respect to the operation signal can be corrected substantially linearly. Therefore, in the hydraulic servo device, the controllability of the entire system can be improved even if the characteristic of the control amount with respect to the operation signal is non-linear due to the viscosity of the oil, the response delay of the valve, the friction of the slide surface, and the like.

According to a second aspect of the present invention, there is provided the hydraulic servo system according to the first aspect, in which the operation signal output means by the lamp output command means has a range of control amounts of the controlled object with respect to a lamp-like operation signal. The conversion table creating means converts the operation signal for each control amount divided based on the division number set by the division number setting means. It creates a conversion table.

Therefore, according to the hydraulic servo system of the second aspect of the present invention, the conversion table for each control amount appropriately determined can be created in accordance with the change width (range) of the control amount of the controlled object. it can.

[Brief description of drawings]

FIG. 1 is a block diagram of a hydraulic servo device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a correction data measuring process of a controller of the hydraulic servo device.

FIG. 3 is a flowchart showing a correction table creating process of the controller.

FIG. 4 is a flowchart showing a correction execution process of the controller.

FIG. 5 is a diagram showing a ramp-shaped command voltage of the hydraulic servo device.

FIG. 6 is a diagram showing speed characteristics of the hydraulic servo device with respect to the ramp-shaped command voltage.

FIG. 7 is a diagram showing speed characteristics with respect to a command voltage of a correction table array of the controller.

FIG. 8 is a diagram showing a relationship between a pre-correction command voltage and a post-correction command voltage of the controller.

[Explanation of symbols]

1 ... Controller, 2 ... Valve driver, 3 ... Servo valve, 4 ... Hydraulic cylinder, 5 ... Slide, 6 ... Sensor.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshinari Sasaki               No. 1 Nishiichitsuya, Settsu City, Osaka Prefecture Daiki               Yodogawa Manufacturing Co., Ltd.                (56) Reference JP-A-63-118813 (JP, A)                 JP-A-57-57304 (JP, A)

Claims (2)

(57) [Claims] 1. A controlled object (2, 3,
(4, 5) control amount detecting means (6) for detecting the control amount, and operation signal output for outputting an operation signal to the valve for controlling the oil flow rate of the controlled object (2, 3, 4, 5). In the hydraulic servo device including means (11), lamp output command means for causing the operation signal output means (11) to output a ramp-shaped operation signal that increases in proportion to time.
(12) and the control amount detected by the control amount detection means (6) with respect to the lamp-shaped operation signal output from the operation signal output means (11) by the lamp output command means (12) The operation signal output means (11) based on the characteristic curve of
A conversion table creating means (13) for creating a conversion table for converting and outputting the operation signal so that the operation signal output from the control object and the control amount of the controlled object (2, 3, 4, 5) are substantially proportional to each other. And a conversion table storage means (14) for storing the conversion table created by the conversion table creation means (13) , wherein the operation signal output means (11) is the conversion table storage means.
Conversion based on the conversion table stored in column (14)
By outputting the above-mentioned operation signal
A hydraulic servo system characterized by making the characteristics of the entire robot system linear . 2. The hydraulic servo apparatus according to claim 1, wherein the controlled object (2,
3, 4, 5) is provided with division number setting means (15) for setting the number of divisions for dividing the control amount range, and the conversion table creating means (13) is provided with the division number setting means (15). The hydraulic servo device is characterized in that a conversion table for converting the operation signal is created for each control amount determined based on the number of divisions set by (1).