JP2018190138A - Position control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize control that more accurately reflects a position command.SOLUTION: A position control system of an embodiment includes a command analysis unit, filter arithmetic unit, deviation deduction unit, correction unit, switching unit, and position control unit. The command analysis unit outputs an analyzed position command, which is obtained by analyzing a high-order position command, at intervals of a predetermined cycle. The filter arithmetic unit outputs a computed position command, which is a result of computation performed on the analyzed position command in order to attenuate a predetermined frequency component. The deviation deducation unit integrates a difference between the analyzed position command and the computed position command, which is provided by the filter arithmetic unit, so as to deduce an integral command deviation. When the analyzed position command is zero, the integral command deviation is equal to or smaller than a first threshold, and a value represented by the computed position command is equal to or smaller than a second threshold, the correction unit outputs the integral command deviation. The switching unit selects either the integral command deviation or the computed position command, and outputs the selected one to the position control unit as a position command. The position control unit controls the position of an object of control on the basis of the position command outputted from the switching unit.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a position control device.

  2. Description of the Related Art Conventionally, there is known a position control device that performs position control so that a position of a control target detected by a position detection unit matches a position in a position command. In this position control device, filter calculation processing may be performed on the position command. However, when the filter calculation is performed as described above, the information corresponding to the position command and the information included in the result of the filter calculation do not match, and position control may not be performed accurately.

Japanese Patent No. 3899824

  The problem to be solved by the present invention is to provide a position control device capable of performing control reflecting a position command more accurately.

  The position control device according to the embodiment includes a command analysis unit, a filter calculation unit, a deviation derivation unit, a correction unit, a switching unit, and a position control unit. The command analysis unit analyzes the upper position command, which is information related to the position, and outputs the analyzed analysis position command at a predetermined cycle. The filter calculation unit outputs a post-calculation position command that is a calculation result for attenuating a predetermined frequency component with respect to the analysis position command output by the command analysis unit. The deviation deriving unit integrates a difference between the analysis position command and the post-calculation position command calculated by the filter calculation unit to derive an integration command deviation. The correction unit has an analysis position command of zero, an integral command deviation derived by the deviation deriving unit is equal to or less than a first threshold value, and a value indicated by the post-computation position command calculated by the filter calculation unit is a second value. When the value is equal to or less than the threshold value, an integration command deviation is output. The switching unit selects either the integration command deviation output from the correction unit or the calculated position command calculated by the filter calculation unit, and outputs the selected position command to the position control unit. The position control unit controls the position of the control target based on the position command output from the switching unit.

The figure which shows the function structure of the position control system 1 containing the position control apparatus 20. FIG. 4 is a flowchart showing a flow of processing executed by the position control device 20. The figure which shows typically the relationship between an analysis position command and the post-calculation position command calculated by the filter calculating part 30, and an integral command deviation. The figure which shows the case where the position command after a calculation calculated by the filter calculating part 30 undershoots in the state without an analysis position command. 5 is a flowchart showing a flow of processing executed by a command analysis unit 22; The conceptual diagram when a high-order position command is smoothed.

  Hereinafter, a position control device according to an embodiment will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram showing a functional configuration of a position control system 1 including a position control device 20. The position control system 1 includes, for example, a higher order command device 10 and a position control device 20. The higher order command device 10 includes, for example, an operation unit such as a keyboard and a touch panel, and a display unit that displays an image. The higher order command device 10 outputs a position command (information indicating the position of the control target, an index or a value indicating the movement distance) to the position control device 20 according to the information input to the operation unit by the operator. To do. Hereinafter, the position command output from the high-order command device 10 may be referred to as “high-order position command”.

  The upper position command is output to the position control device 20 by a pulse method, a communication method, or a bus method. In the pulse method, the higher order command device 10 outputs a higher position command by outputting a pulse corresponding to the moving distance. In the pulse method, the moving distance of the control target for one pulse is determined such that the moving distance of the control target of one pulse is 1 μm. The speed to the target position is represented by the pulse frequency. In the communication method or the bus method, for example, the higher order command device 10 outputs a value corresponding to the movement distance to be controlled, a value corresponding to the speed or the like as a higher position command at a predetermined cycle and a predetermined timing. Specifically, the higher order command device 10 outputs, for example, information such as a distance and a speed at which the control target is to be moved between 5 m [sec] every 5 m [sec].

  The position control device 20 includes, for example, a command analysis unit 22, a filter calculation unit 30, a deviation derivation unit 32, a correction unit 40, a switching unit 49, a position control unit 50, and a speed control unit 60. The position control device 20 may be realized, for example, when a processor such as a CPU (Central Processing Unit) executes a program stored in a storage device of the position control device 20. Further, all or a part of the position control device 20 is realized by hardware such as LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), and the functions of these functional units. A circuit configuration for realizing the above may be provided. These functional units may be realized by cooperation of software and hardware.

  The command analysis unit 22 analyzes the upper position command so that it can be processed in the position control device 20 and outputs it as a position command to the filter calculation unit 30 at a predetermined cycle. To be able to process in the position control device 20 is to output information indicating the movement distance of the controlled object to the filter calculation unit 30 in accordance with the position control cycle (for example, 100 μ [sec]) of the position control device 20. . Hereinafter, the position command analyzed and output by the command analysis unit 22 may be referred to as “analysis position command”.

  The filter calculation unit 30 acquires the analysis position command output from the command analysis unit 22, attenuates a predetermined frequency component (mainly a low frequency band around 40 Hz) and attenuates the acquired analysis position command. A position command is output to the position controller 50. The filter used in the filter calculation unit 30 is, for example, a notch filter or an IIR (Infinite impulse response) filter. Hereinafter, the position command calculated by the filter calculation unit 30 may be referred to as “post-calculation position command”.

The deviation deriving unit 32 derives an integration command deviation obtained by integrating a command deviation that is a difference between the analysis position command and the post-calculation position command calculated by the filter calculation unit 30.
The correction unit 40 includes, for example, a first determination unit 44, a second determination unit 46, and an output control unit 48.

  The first determination unit 44 determines whether or not the integral command deviation derived by the deviation deriving unit 32 is equal to or less than a first threshold value. The second determination unit 46 determines whether or not the post-calculation position command calculated by the filter calculation unit 30 is less than or equal to the second threshold value.

The output control unit 48 is configured such that the integrated command deviation derived by the deviation deriving unit 32 is equal to or smaller than the first threshold value and the post-computed position command calculated by the filter calculating unit 30 is the second in a state where there is no analysis position command. When the value is equal to or less than the threshold value, an integration command deviation is output. When the integration command deviation is output from the output control unit 48, the integration command deviation output from the output control unit 48 is input to the position control unit 50 as a position command. When the integration command deviation is not output from the output control unit 48, the post-computation position command is input to the position control unit as a position command.
The series of processes as described above can be summarized as shown in FIG.
This will be described in more detail with reference to FIG.

  First, the filter calculation unit 30 performs a filter calculation process on the analysis position command acquired from the command analysis unit 22 to obtain a calculated position command (step S100). Next, the deviation deriving unit 32 derives an integral command deviation (step S102).

  Here, the relationship between the analysis position command input to the filter calculation unit 30 and the post-calculation position command output from the filter calculation unit 30 will be described. For example, when an analysis position command is input to the filter calculation unit 30, the filter calculation is performed and the calculation result is output. In the beginning when the analysis position command is input, the command deviation, which is the difference between the input to the filter calculation unit 30 and the output from the filter calculation unit 30, is filtered by the filter calculation unit 30. Because it is, it becomes big. For example, if the input analysis position command is “100” and the output post-computation position command is “1”, the command deviation is “99”. Also, in the filter calculation of the next cycle, if the input analysis position command is “100” and the output post-computation position command is “10”, the integral command deviation is the current command deviation “90” and the previous time The command deviation “99” is integrated to “189”. As time elapses, the calculated position command catches up with the analysis position command, and the command deviation becomes smaller.

  On the other hand, at the end of the analysis position command obtained by analyzing the upper position command, the integral command deviation becomes small. For example, if the analysis position command input at the end is “1” and the post-computation position command is “90”, the command deviation is “−89”, and the previous integration command deviation is “189”. The integration command deviation this time is “100 (189-89)”.

  Further, even after the input of the analysis position command corresponding to the upper position command is completed, the calculation result of the filter is output. For example, even if the analysis position command input to the filter calculation unit 30 is “0”, the post-calculation position command output may be “100” due to an output delay with respect to the input by the filter calculation. is there.

  As described above, since the integration command deviation tends to decrease after the end of the analysis position command or the input of the analysis position command to the filter calculation unit 30 is completed, the input of the analysis position command to the filter calculation unit 30 is completed. In this case, when the absolute value of the integral command deviation is equal to or less than the first threshold value, it can be estimated that it is close to the timing at which all post-calculation position commands calculated by the filter calculation unit 30 are output.

  Next, the correction unit 40 determines whether or not the input of the analysis position command to the filter calculation unit 30 has been completed (step S104). When the input of the analysis position command is not completed, the position command that is an input to the position control unit 50 is only the post-calculation position command that has been subjected to the filter calculation by the filter calculation unit 30 (step S106).

  When the input of the analysis position command to the filter calculation unit 30 is completed, the first determination unit 44 determines whether or not the absolute value of the integral command deviation is equal to or less than a first threshold value (for example, “3”). (Step S108).

  If the absolute value of the integral command deviation is not less than or equal to the first threshold value, the process proceeds to step S106. When the absolute value of the integral command deviation is equal to or smaller than the first threshold value, the process proceeds to step S110.

  When the input of the analysis position command to the filter calculation unit 30 is completed and the absolute value of the integral command deviation is equal to or smaller than the first threshold value, the second determination unit 46 calculates the post-calculation position command calculated by the filter calculation unit 30. It is determined whether or not the absolute value is equal to or smaller than a second threshold value (step S110). The second threshold value may be the same as or different from the first threshold value. If the absolute value of the calculated position command calculated by the filter calculation unit 30 is not equal to or less than the second threshold value, the process proceeds to step S106. When the absolute value of the calculated position command calculated by the filter calculation unit 30 is equal to or smaller than the second threshold value, the output control unit 48 outputs an integration command deviation (step S112). When the integration command deviation is output, the integration command deviation is input to the position control unit 50 as a position command. (Step S114) Thereby, the total of analysis position commands (command position command) input to the filter calculation unit 30 matches the total of position commands input to the position control unit 50.

  In this way, the switching unit 49 selects either the integration command deviation output from the correction unit 40 or the post-calculation position command calculated by the filter calculation unit 30, and outputs the position command to the position control unit 50 as a position command. .

  The position control unit 50 acquires position information (feedback signal) detected by a position detection unit (not shown) that detects the position of a control target (for example, a motor). The position detection unit is an encoder, a resolver, or the like that optically or magnetically detects the position of the control target. Based on the acquired position information, the calculated position command calculated by the filter calculation unit 30, and the integration command deviation output by the output control unit 48, the position control unit 50 The feedback control is performed so that the position of the control target matches. The position control unit 50 generates a speed command based on the result of the feedback control and outputs it to the speed control unit 60.

  The speed control unit 60 derives a current command such that the speed command acquired from the position control unit 50 matches the speed calculated by the speed calculation unit that calculates the operation speed (for example, the rotation speed of the motor) to be controlled. And output to the controlled object. The control target controls the own apparatus based on the current command output by the speed control unit 60. By controlling the controlled object in this way, the position of the actuator or the like controlled by the operation of the controlled object is controlled.

  FIG. 3 is a diagram schematically showing the relationship between the analysis position command and the post-calculation position command and the integral command deviation calculated by the filter calculation unit 30. FIG. 3A shows the time history of the position indicated by the analysis position command. In FIG. 3B, the vertical axis represents the analysis position command for each processing cycle, and the horizontal axis represents time. FIG. 3C shows the time history of the position indicated by the post-calculation position command. The vertical axis of (d) of FIG. 3 shows the post-calculation position command for each processing cycle, and the horizontal axis shows time. The vertical axis of (e) of FIG. 3 shows the command deviation which is the difference between the analysis position command and the calculated position command, and the horizontal axis shows time. The vertical axis of (f) in FIG. 3 indicates an integral command deviation obtained by integrating the command deviation, and the horizontal axis indicates time.

  FIG. 4 is a diagram illustrating a case where the post-computation position command calculated by the filter computation unit 30 undershoots in the absence of the analysis position command. The description overlapping with FIG. 3 is omitted. The vertical axis of (a) in FIG. 4 indicates post-computation position commands S <b> 1 to Sn output every processing cycle of the filter computation unit 30. As shown in the drawing, in the calculation result of the filter calculation unit 30, there may be a case where an after-computed position command such as post-calculated position commands Sn-2 to Sn is output. In this case, the absolute value of the integral command deviation may be equal to or less than the first threshold value (Th1). The absolute value of the integral command deviation is equal to or less than Th1 in the period of time Tn−1 and Tn in FIG. However, even if the absolute value of the integral command deviation is equal to or less than the first threshold value, the post-calculation position command of the calculation result of the filter calculation unit 30 may exceed the second threshold value (Th2). The absolute value of the integral command deviation is equal to or less than Th1 in the period of time Tn-1 and Tn in FIG. 4A, but the absolute value | Sn-1 | of the post-computation position command is equal to or greater than Th2. In this case, there is a possibility that all the results of the filter operation are not completely output. In FIG. 4, since the absolute value of the integral command deviation is equal to or less than Th1 during the period of time Tn−1 and Tn, the correction unit 40 outputs the integral command deviation at that time, and the integral command deviation is the position control unit. 50 is input as a position command, and it is determined that the input of the position command to the position control unit 50 is completed. However, with that alone, there is actually Sn to Sn + 3 after the post-calculation position command Sn−1, which is different from the original movement, and thus there is a possibility that vibration will occur in the controlled object.

  For this reason, the correction unit 40 has an absolute value of an integral command deviation obtained by integrating a command deviation which is a difference between the analysis position command input to the filter calculation unit 30 and the post-calculation position command output by the filter calculation unit 30. Even if it is determined that the value is equal to or less than the first threshold value, the integral command deviation is not output if the absolute value of the post-calculation position command is not equal to or less than the second threshold value. As a result, erroneous determination when the post-computation position command undershoots can be suppressed.

  As described above, in the state where there is no analysis position command, the correction unit 40 has the absolute value of the integration command deviation equal to or less than the first threshold value and the absolute value of the post-calculation position command calculated by the filter calculation unit 30. Is equal to or less than the second threshold value, the integral command deviation is output to the position control unit 50 as a position command in order to output the integral command deviation. Thereby, the reliability of the position command input to the position control unit 50 can be improved, and the control reflecting the position command more accurately can be realized. Moreover, the end timing of the calculation of the filter calculation unit 30 can be quickly determined.

(Second Embodiment)
Hereinafter, the second embodiment will be described. In the second embodiment, the command analysis unit 22 smoothes the upper position command. When the upper position command is not commanded as in the second embodiment, it may not be applicable. This will be described below with reference to FIGS.

FIG. 5 is a flowchart showing a flow of processing executed by the command analysis unit 22, and FIG. 6 is a conceptual diagram when the command position analysis unit 22 smoothes the upper position command.
The command analysis unit 22
(1) The first upper position command (P1 in FIG. 6) is acquired at the first timing. When the first timing is the first time, the time interval from the second timing, which is the next timing, is not known. It outputs to the filter calculating part 30 (P11-P14 in the example of FIG. 6). The predetermined cycle is the same cycle as the position control cycle processed by the position control unit 50. Assuming that the upper limit value of the number of divisions set in advance is Nm, P11 = P12 =. For example, if P1 is 1000, Nm is 10, and the predetermined period is 100 μsec, 1000/10 = 100 (P11, P12,...) Is output to the filter calculation unit 30 every 100 μsec.
A series of processing flow (1) is START → S200 → S202 → S204 → RETURN in FIG.
next,
(2) The second upper position command (P2 in FIG. 6) is acquired at the second timing after the first timing, and the time interval between the first upper position command and the second upper position command (FIG. In the example of 6, the sum of the second upper position command and the remaining portion of the first analysis position command that has not been output is smoothed based on the time interval from P1 to P2, the time for four times of a predetermined period) Then, the smoothed second analysis position command is output to the filter calculation unit 30 every predetermined period. Smoothing is the upper limit value of the preset number of divisions for the first time, and thereafter, the number of divisions is a value twice the value obtained by dividing the time interval between each timing by a predetermined period (number of cycles N). Dividing by the number of divisions. Assuming that P1 = P2 = 1000 and a predetermined cycle: 100 μsec, in the example of FIG. 6, the analysis position command for four times of the predetermined cycle is output to the filter calculation unit 30. -100 × 4 = 600, and P2 is 1000, so 600 + 1000 = 1600 is twice the period 4 times (N = 4), 8 is the division number, and 200 divided by 8 (P15, P16,...) The data is output to the filter calculation unit 30 every 100 μsec.
The series of processing flow (2) is START → S200 → S202 → S206 → RETURN in FIG.

(3) The third upper position command (P3 in FIG. 6) is acquired at the third timing after the second timing, and the third upper position command and the second analysis position command are not output. Based on the time interval between the second upper position command and the third upper position command (in the example of FIG. 6, the time interval from P2 to P3, the time for four times in a predetermined cycle). Then, the summed value is smoothed and output to the filter operation unit 30 as a third analysis position command for each predetermined period.
The flow of a series of processes in (3) is START → S200 → S202 → S206 → RETURN in FIG.

  In addition, the command analysis part 22 smoothes a high-order position command as "N = 2", when a high-order position command is acquired for every position control period. In the above example, the upper position command is described as being input to the command analysis unit 22 when four position control cycles have elapsed. However, the present invention is not limited to this, and the cycle in which the upper position command is input is variable. Even in this case, the command analysis unit 22 performs the same processing as described above.

  In this way, the command analysis unit 22 smoothes the input upper position command, so that the filter calculation of the filter calculation unit 30 can be made unnecessary.

  Further, the command analysis unit 22 according to the second embodiment automatically smoothes the upper position command automatically based on the cycle in which the upper position command is input even when the cycle of the input upper position command has changed. be able to.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Position control system 20, 20A ... Position control apparatus, 22 ... Command analysis part, 30 ... Filter operation part, 40 ... Correction | amendment part, 32 ... Deviation derivation part, 44 ... 1st determination part, 46 ... 2nd determination part 48 ... Output control unit 49 ... Switching unit 50 ... Position control unit

Claims (10)

A command analysis unit that analyzes the upper position command, which is information related to the position, and outputs the analyzed analysis position command at a predetermined cycle;
A filter calculation unit that outputs a post-computation position command that is a calculation result for attenuating a predetermined frequency component with respect to the analysis position command output by the command analysis unit;
A deviation derivation unit that integrates a difference between the analysis position command and a post-calculation position command calculated by the filter calculation unit, and derives an integral command deviation;
The analysis position command is zero, the integral command deviation derived by the deviation deriving unit is less than or equal to the first threshold value, and the value indicated by the calculated position command computed by the filter computation unit is less than or equal to the second threshold value. In some cases, a correction unit that outputs an integral command deviation;
A switching unit for selecting either the integration command deviation output from the correction unit and the post-computation position command computed by the filter computation unit;
Based on the position command output from the switching unit, a position control unit that controls the position of the control target;
A position control device comprising: The filter calculation unit includes a notch filter that attenuates a component of a predetermined frequency band.
The position control device according to claim 1. When the correction unit determines that the input of the analysis position command output by the command analysis unit to the filter calculation unit is not completed, the switching unit is calculated by the filter calculation unit to the position control unit. Output a position command after calculation.
The position control device according to claim 1 or 2. When the correction unit determines that the input of the analysis position command output by the command analysis unit to the filter calculation unit is completed, the integral command deviation derived by the deviation deriving unit is equal to or less than a first threshold value. Determine if there is,
The position control device according to claim 1 or 2. When the correction unit determines that the integral command deviation derived by the deviation deriving unit is not equal to or less than a first threshold, the switching unit outputs the calculated position command calculated by the filter calculating unit to the position control unit. Output,
The position control device according to claim 4. When the correction unit determines that the post-computation position command output from the filter computation unit is not equal to or less than a second threshold value, the switching unit performs a post-computation position command computed by the filter computation unit to the position control unit. Output
The position control device according to claim 4. In the switching unit, the correction unit determines that the integral command deviation derived by the deviation deriving unit is equal to or less than a first threshold value, and the post-calculation position command output from the filter calculating unit is equal to or less than a second threshold value. In this case, the integral control deviation output from the correction unit is output to the position control unit.
The position control device according to claim 4. The command analysis unit acquires a first upper position command at a first timing, smoothes the acquired first upper position command with an upper limit value of a preset number of divisions, and performs a smooth first analysis position. Outputting a command to the filter calculation unit at predetermined intervals;
The position control device according to any one of claims 1 to 7. The command analysis unit acquires a second upper position command at a second timing after the first timing, and acquires the first analysis position command that has not been output to the filter calculation unit. The sum of the second upper position command and the second upper position command is smoothed based on the interval between the first upper position command and the second upper position command, and the smoothed second analysis position command is converted into a predetermined cycle. Each output to the filter operation unit,
The position control device according to claim 8. The command analysis unit acquires a third upper position command at a third timing after the second timing, and acquires the second analysis position command that has not been output to the filter calculation unit. The sum of the third upper position command and the third upper position command is smoothed based on the interval between the second upper position command and the third upper position command. Output to the filter operation unit for each period;
The position control device according to claim 9.

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