JP2015182141A - Motion error measuring method, motion error measuring device and machine tool equipped with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motion error measuring device and so on which can measure a movement error of an action part simply and with a high accuracy compared to prior one.SOLUTION: A motion error measuring device 1 includes: an acceleration sensor 2 for detecting an acceleration in a feed axial direction of an action part; an actual acceleration data calculation part 5 which calculates actual acceleration data by multiplying an output of the acceleration sensor 2 by a sensitivity coefficient; a data calibration part 6 which calculates calibration actual position data in which the sensitivity coefficient is adjusted in such a manner that a difference between maximum values or minimum values in actual position data, which is obtained by double integration of the calculated actual acceleration data, and command position data, or between differences between the maximum values and the minimum values is involved within a predetermined acceptable range; and a movement error calculation part 7 which calculates a movement error of the action part by taking a difference between the calibration actual position data and the command position data.

Description

  The present invention relates to a method and an apparatus for measuring a motion error of the operation unit in a positioning device including a feed device that moves the operation unit by one or more feed axes and a numerical control device that numerically controls the feed device. .

  The feeding device usually includes a guide unit that guides the motion of the operation unit and a drive unit that moves the operation unit. For example, the guide unit includes a rolling guide mechanism and a sliding guide mechanism, The drive unit includes a ball screw, a nut fixed to the operation unit and screwed to the ball screw, and rotating the ball screw about the axis thereof, so that the nut and the operation unit coupled thereto are arranged. And a drive motor to be moved.

  The numerical control device that numerically controls the feeding device generates a control signal based on the target movement position (command position) of the operation unit, drives the drive motor under the control signal, and drives the drive motor. By rotating the ball screw about the axis, the operation unit is moved to the target movement position.

  The field to which the above-mentioned feeding device is applied can typically be exemplified by the field of machine tools, but it is also applied to various other fields. In recent years, more and more accurate positioning control is required. It has come to be. In particular, when a follow-up delay occurs when the feed direction is reversed, there is a problem that so-called quadrant protrusions are produced when the feed axes of a feed device having two or more feed axes are simultaneously controlled.

  Thus, from such a background, there has been a demand for a measuring apparatus that can measure the motion accuracy of the operating unit simply and with high accuracy, and one of them is disclosed in Patent Document 1 below. A motion trajectory measuring device has been proposed.

  The motion trajectory measuring apparatus includes an accelerometer for measuring the acceleration of the machine and a motion trajectory measuring unit for measuring the motion trajectory of the machine, and the motion trajectory measuring unit calculates the acceleration measured by the accelerometer. The machine position is obtained by second-order integration, and the profile of the machine position substantially matches the estimated position estimated by a model that simulates the responsiveness of the position of the machine with respect to the command position or the profile of the detected position. Thus, the movement position of the machine is measured by correcting the machine position.

International Publication No. 2010/067651

By the way, the accelerometer is configured to output a voltage corresponding to the applied acceleration, and a sensitivity coefficient provided by a measuring instrument manufacturer is used to calculate the acceleration from the output voltage. When the coefficient is K and the output voltage is V, the acceleration G is expressed by the following equation: G = K · V
Is calculated by

  However, according to the knowledge of the present inventors, there are individual differences in the response characteristics of the accelerometer, and the response depends on the use conditions of the accelerometer, that is, the ambient temperature used and the power applied to the accelerometer. The characteristic changes. For this reason, even if the sensitivity coefficient provided by the measuring instrument manufacturer is used as it is, an accurate acceleration cannot be calculated, and the actual position data obtained from this acceleration is not accurate.

  Therefore, in order to measure the motion error of the operation unit with high accuracy, it is necessary to calibrate the sensitivity coefficient for calculating the acceleration based on the output voltage of the accelerometer. Since this point has not been addressed, further improvements were necessary.

  The present invention has been made in view of the above circumstances, and a motion error measuring method and apparatus capable of measuring a motion error of a motion unit in a simpler manner and with higher accuracy than in the prior art, and the apparatus. The purpose is to provide a machine tool equipped with

In order to solve the above problems, the present invention relates to a motion error of the motion unit in a positioning device having a feed device that moves the motion unit by one or more feed shafts and a numerical control device that numerically controls the feed device. A method of measuring,
The numerical control device controls the feed axis of the feed device to move the operation unit to a command position according to a function of time for drawing a sine wave and output an acceleration sensor that detects the acceleration of the operation unit Sampling at predetermined time intervals, multiplying the obtained output data by a sensitivity coefficient, and calculating the actual acceleration data of the operating unit in the feed direction of the feed shaft,
The difference between the local maximum values, the local minimum values, or the difference between the local maximum value and the local minimum value in the actual position data obtained by second-order integration of the actual acceleration data and the command position data is determined in advance. A data calibration step of calculating calibration actual position data in which the sensitivity coefficient is adjusted so as to be within an allowable range;
The present invention relates to a motion error measurement method including a motion error calculation step of calculating a motion error of the operation unit by taking a difference between calibration actual position data obtained in the data calibration step and command position data.

And this movement error measuring method is suitably implemented with the following devices. That is, this device is a measuring device that measures a motion error of the operating unit of a positioning device having a feeding device that moves the operating unit by one or more feed axes and a numerical control device that numerically controls the feeding device. There,
An acceleration sensor that is controlled by the numerical controller and detects an acceleration in the axial direction of the feed axis of the operating unit that moves to a command position according to a function of time for drawing a sine wave;
An actual acceleration data calculation unit that samples the output of the acceleration sensor at predetermined time intervals, multiplies the obtained output data by a sensitivity coefficient, and calculates actual acceleration data of the operation unit in the feed direction of the feed shaft; ,
The actual position data obtained by second-order integration of the actual acceleration data calculated by the actual acceleration data calculation unit, and the respective maximum values, or the minimum values, or the maximum value and the minimum value in the command position data, A data calibration unit that calculates calibration actual position data in which the sensitivity coefficient is adjusted so that the difference between the differences falls within a predetermined allowable range;
The present invention relates to a motion error measuring device including a motion error calculation unit that calculates a motion error of the motion unit by taking a difference between calibration actual position data calculated by the data calibration unit and command position data.

  According to the motion error measuring device, first, when the feed axis of the feed device is controlled by the numerical control device and the operation unit is moved to a command position according to a function of time for drawing a sine wave, The acceleration of the operating unit in the axial direction of the feed axis is detected by the acceleration sensor. Then, the actual acceleration data calculation unit samples the output of the acceleration sensor at a predetermined time interval, and multiplies the obtained output data by a sensitivity coefficient to thereby determine the actual acceleration of the operation unit in the feed direction of the feed shaft. Data is calculated.

Next, in the data calibration unit, actual position data is calculated by second-order integration of the actual acceleration data calculated by the actual acceleration data calculation unit, and the calculated actual position data and the command position data, The actual position data is calibrated by adjusting the sensitivity coefficient so that the difference between the respective local maximum values, the local minimum values, or the difference between the local maximum value and the local minimum value falls within a predetermined allowable range. Is done. The calibration process, the sensitivity coefficient used in the actual acceleration data calculating unit K, a sensitivity coefficient after adjustment and K _i, when the actual position data obtained by adjusting the sensitivity coefficient is referred to as adjusting the actual position data The adjusted actual position data is, for example, the following formula adjusted actual position data = actual position data × (K / K _i )
The adjustment actual position data that can be calculated by the above-mentioned and within the allowable range is set as the calibration actual position data.

  As described above, the response characteristics of the acceleration sensor vary depending on the usage conditions, and there are individual differences. Therefore, even if the sensitivity coefficient provided by the measuring instrument manufacturer is used as it is, accurate acceleration can be calculated. In addition, the actual position data obtained from this acceleration is not accurate.

  In the present invention, the sensitivity coefficient is adjusted so that the difference between the actual position data obtained by second-order integration of the actual acceleration data and the command position data is within a predetermined allowable range. Therefore, accurate actual position data can be obtained.

  Next, the motion error measuring unit calculates the motion error of the operating unit by taking the difference between the actual calibration position data calculated by the data calibration unit and the command position data.

  As described above, according to the present invention, accurate actual position data of the operation unit can be obtained, and by comparing this with the command position data, the motion error of the operation unit can be calculated more accurately than before. can do. In addition, since a measuring instrument that is easy to handle, such as an acceleration sensor, is used, the measurement operation can be performed easily.

In the present invention, the data calibration unit is
Processing to match the phase of the command acceleration data obtained by second-order differentiation of the data related to the command position and the actual acceleration data calculated by the actual acceleration data calculation unit;
The local maximum values, the local minimum values, or the local maximum values in the actual position data obtained by second-order integration of the actual acceleration data after phase alignment and the command position data corresponding to the command acceleration data after phase alignment. The process of calculating the calibration actual position data in which the sensitivity coefficient is adjusted so that the difference between the difference between the value and the minimum value falls within a predetermined allowable range may be executed.

  The actual position data calculated from the output value of the acceleration sensor and the command position data do not necessarily match the time axes, in other words, the phases do not match. Therefore, even if the calibration actual position data and the command position data in a state where the phases are shifted are compared, an accurate motion error cannot be calculated. Therefore, as described above, the phase of the command acceleration data obtained by second-order differentiation of the data related to the command position and the actual acceleration data calculated by the actual acceleration data calculation unit are matched, and the phase after phase matching is adjusted. The actual position data obtained from the actual acceleration data and the command position data corresponding to the command acceleration data are used to calculate the calibration actual position data, and the calculated actual position data and the command position data are compared to operate the operation unit. By calculating the motion error, it is possible to calculate the motion error with higher accuracy.

In the present invention, the data calibration unit is
A process of calculating the actual position data by second-order integration of the actual acceleration data;
Processing to match the phase of the calculated actual position data and the command position data;
The difference between the local maximum values, the local minimum values, or the difference between the local maximum value and the local minimum value in the actual position data after phase alignment and the command position data is within a predetermined allowable range. And a process of calculating calibration actual position data in which the sensitivity coefficient is adjusted.

  In this way, even if the actual position data obtained by second-order integration of the actual acceleration data is phase-matched with the command position data, the calibration actual position data is calculated in the same manner as described above. The error can be calculated with higher accuracy.

In the present invention, the motion error calculation unit
Processing to match the phase of the calibration actual position data and the command position data;
The process of calculating the motion error of the operation unit may be executed by taking the difference between the calibration actual position data after phase alignment and the command position data.

  As described above, the phase difference between the calibration actual position data and the command position data is calculated before calculating the difference between the calibration actual position data and the command position data. It can be calculated with accuracy.

  The actual speed data calculating unit is preferably configured to calculate the actual acceleration data using an average value of the output data obtained by repeatedly operating the operating unit for a plurality of cycles.

  In addition, it is preferable that the motion error calculation unit is further configured to remove the fluctuation component by processing the calculated motion error data using a high-pass filter.

  In addition, the motion error calculation unit further includes a quadrant projection by taking a difference between the maximum value and the minimum value of the data within a predetermined time width including the time zone indicating the maximum fluctuation in the calculated motion error data. It is preferably arranged to calculate the quantity.

  Preferably, the acceleration sensor, the actual acceleration data calculation unit, the data calibration unit, and the motion error calculation unit are stored in a storage box, and the storage box is configured to be detachable from the operation unit. If it does in this way, the movement error of the operation part can be measured by simple work of attaching the storage box to the operation part and moving the operation part.

  Further, the motion error measuring device of the present invention is preferably used for a machine tool including a positioning device having a feeding device that moves an operation unit by one or more feeding shafts and a numerical control device that numerically controls the feeding device. be able to.

  As described above, according to the present invention, by adjusting the sensitivity coefficient, the difference between the actual position data obtained by second-order integration of the actual acceleration data and the command position data is within a predetermined allowable range. Since the actual position data of the operating unit can be obtained, the motion error of the operating unit can be calculated with higher accuracy than in the prior art. In addition, since a measuring instrument that is easy to handle, such as an acceleration sensor, is used, the measurement operation can be performed easily.

1 is a perspective view showing a machine tool according to an embodiment of the present invention. It is the block diagram which showed schematic structure of the movement error measuring apparatus which concerns on this embodiment. It is a flowchart for demonstrating the process of the exercise | movement error measuring device which concerns on this embodiment. It is the flowchart which showed the phase alignment process in this embodiment. It is the flowchart which showed the calibration actual position data calculation process in this embodiment. (A) is explanatory drawing which showed the command position data of the X-axis direction, (b) is explanatory drawing which showed the command position data of the Y-axis direction. It is explanatory drawing which showed the average real acceleration data calculated by the real acceleration data calculation part in this embodiment, (a) is explanatory drawing which showed the average real acceleration data of a X-axis direction, (b) is Y It is explanatory drawing which showed the average real acceleration data of the axial direction. It is explanatory drawing for demonstrating the phase alignment process in this embodiment. It is explanatory drawing for demonstrating the calibration actual position data calculation process in this embodiment. It is explanatory drawing for demonstrating the exercise | movement error calculation process in this embodiment. It is the flowchart which showed the calibration actual position data calculation process in other embodiment of this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an example of a machine tool to which a motion error measuring device according to the present embodiment is mounted, and FIG. 2 is a block diagram showing a schematic configuration of the motion error measuring device according to the present embodiment. It is.

[Schematic configuration of machine tool]
As shown in FIG. 1, the machine tool 10 of this example is movable in a vertical direction, that is, in the Z-axis direction, on a bed 11, a column 12 erected on the rear side of the bed 11, and the front surface of the column 12. A spindle head 13 disposed on the spindle head 14, a spindle 14 rotatably held by the spindle head 13, and a carriage 16 disposed on the front bed 11 so as to be movable in the front-rear direction, that is, in the Y-axis direction. On the carriage 16, there is provided a table 18 and the like disposed so as to be movable in the X-axis direction orthogonal to the Y-axis.

  The spindle head 13 is driven in the Z-axis direction by a feeding device 15, the carriage 16 is driven in the Y-axis direction by a feeding device 17, and the table 18 is driven by the feeding device 19 in the X-axis direction. The feeding devices 15, 17, and 19 are numerically controlled by the numerical controller 20. The feeding devices 15, 17, 19 and the numerical control device 20 constitute a positioning device. The table 18 is positioned in the XY plane by the operation of the feeding devices 17 and 19, and the spindle 14, the position in the Z-axis direction with respect to the table 18 is positioned by the operation of the feeding device 15.

[Configuration of motion error measuring device]
As shown in FIG. 2, the motion error measuring device 1 of this example includes an acceleration sensor 2 and a display device 3, an actual acceleration data calculation unit 5, a data calibration unit 6, a motion error, which are appropriately stored in a storage box. The data processing unit 4 includes a calculation unit 7 and a command position data storage unit 8. The data processing unit 4 includes a CPU, a RAM, a ROM, and the like.

  In this example, the movement error when the feeding device 17 and 19 are numerically controlled by the numerical control device 20 and the table 18 is caused to perform a circular motion is measured by the motion error measuring device 1. And In this case, the numerical controller 20 generates a command position according to a function of time for drawing a sine wave, and numerically controls the feeders 17 and 19.

  The acceleration sensor 2 outputs a voltage corresponding to the acceleration acting in the X-axis direction and the Y-axis direction, and multiplies the voltage output in each of the X-axis direction and the Y-axis direction by a sensitivity coefficient K. Thus, the acceleration in the X-axis direction and the Y-axis direction that acted on the acceleration sensor 2 can be calculated.

  The display device 3 includes a display unit such as a liquid crystal display, and displays the motion error calculated by the motion error calculation unit 7.

  The command position data storage unit 8 is a functional unit that stores the same command position data as the command position data generated when the numerical controller 20 numerically controls the feeding devices 17 and 19. Command position data in the X-axis direction and command position data in the Y-axis direction for the feeding device 17 are stored in advance. FIG. 6A shows command position data in the X-axis direction, and FIG. 6B shows command position data in the Y-axis direction.

  The actual acceleration data calculation unit 5, the data calibration unit 6, and the motion error calculation unit 7 perform the processes shown in FIG. Hereinafter, details of the processing of each unit will be described.

1. Actual acceleration data calculation unit The actual acceleration data calculation unit 5 is configured such that the feeding devices 17 and 19 are driven by the numerical control device 20 to cause the table 18 to perform a circular motion, and the X axis direction and the Y axis from the acceleration sensor 2. When a voltage in the direction is output, this is sampled at the same time interval as the command position data stored in the command position data storage unit 8, and the sensitivity coefficient K is added to the acquired output voltages in the X-axis direction and the Y-axis direction. To calculate actual acceleration data in the X-axis direction and actual acceleration data in the Y-axis direction (step S1). The actual acceleration data calculated in this way is shown in FIG. FIG. 7A shows actual acceleration data in the X-axis direction, and FIG. 7B shows actual acceleration data in the Y-axis direction.

  Each actual acceleration data is expressed as a product of a sensitivity coefficient and a time function since the output voltage is expressed as a function of time. In this example, it is assumed that the table 18 performs a circular motion a plurality of times (a plurality of cycles) by the numerical controller 20. Here, the sensitivity coefficient K provided by the manufacturer of the acceleration sensor 2 is used.

  Next, the actual acceleration data calculation unit 5 averages the calculated actual acceleration data for a plurality of cycles, and calculates average actual acceleration data for one cycle for each of the X-axis direction and the Y-axis direction (step S2). ). Hereinafter, this average actual acceleration data is simply referred to as “actual acceleration data”. In addition, unless otherwise specified, in the following command position data twice differentiation process, phase alignment process, calibration actual position data calculation process, motion error calculation process and quadrant projection calculation process, the X axis direction and the Y axis direction Each data is processed.

2. Data Calibration Unit The data calibration unit 6 receives actual acceleration data from the actual acceleration data calculation unit 5 (step S3), reads command position data from the command position data storage unit 8 (step S4), and reads the read command The position data is differentiated twice to calculate command acceleration data (step S5). Then, a phase matching process between the actual acceleration data and the command acceleration data is performed (step S6). Specifically, in a calibration actual position data calculation process that compares actual position data and command position data, which will be described later, if the phases of the two data do not match, accurate comparison cannot be performed. Therefore, this phase alignment processing is performed as preprocessing. Hereinafter, this phase matching process will be described in detail with reference to FIGS.

In this phase matching process, first, the counter n is set to an initial value of 1 (step S21), and then the absolute value of the difference between the actual acceleration data and the commanded acceleration data that is the reference value is calculated, and this is totaled. calculates a difference value a _n that (step S22), and then, the calculated difference value a _n is determined whether the following values reference values C _a is the initial value (step S23), the difference value a _n go but if the reference value _{C a} following values, stores the phase difference _{T n (= (n-1} ) ΔT) ( step S24), and the process of replacing the reference value _{C a} by the difference value _{a n} (Step S25), the process proceeds to Step S26. On the other hand, if the difference value _An is greater than the reference value C _a , the process proceeds to step S26.

In step S26, the reference value is shifted in the time axis direction by the shift time ΔT, and after updating the counter n (step S27), it is determined whether the time (n−1) ΔT is equal to or longer than one cycle time. (Step S28), if the cycle time has not been exceeded, the processes of Steps S22 to S28 are repeated. In the processing of steps S22 to S28, the difference value _An is calculated while shifting the reference value in the time axis direction by the shift time ΔT, and the deviation time (n−1) at which the difference value _An is minimized. ΔT is a process for calculating a phase difference T _n a.

Note that the processing at step S22~S28 are relatively coarse interval, that is, large shift time [Delta] T, and to detect the phase difference _{T n} by shifting the reference value, the process in next step S29~ step S38 The reference value is shifted with a shift time Δt shorter than the shift time ΔT from the state in which the reference value is shifted in the time axis direction by the time (T _n −t) to the state in which the reference value is shifted by the time (T _n + t). A more accurate phase difference T _m is calculated. In this way, it is possible to shorten the processing time to calculate an accurate phase difference T _m.

That is, first, in step S29, the reference value is shifted in the time axis direction by time (T _n −t). Next, in step S30, after setting the counter m to the initial value 1, a difference value _Am is calculated by summing up the absolute values of the difference between the actual acceleration data and the reference value (step S31), and then calculated. difference value a _m is determined whether the reference value C _b the following values are the initial value (step S32), if the difference value a _m is following values reference value C _b is the phase difference T _{m (= T n -t + (} m-1) Δt) stores the (step S33), after the reference value _{C b} performing the process of replacing the difference value _{a m} (step S34), the process proceeds to step S35. On the other hand, even when the difference value _{A m} is the reference value _{C b} value greater than the flow proceeds to step S35.

In step S35, the reference value is shifted in the time axis direction by the shift time Δt, and after updating the counter m (step S36), it is determined whether the time (m−1) Δt is equal to or greater than the time 2t. (Step S28) If the time 2t has not been exceeded, the processes of Steps S31 to S37 are repeated. Thus, to calculate accurate phase difference T _m of a commanded acceleration data is a reference value and actual acceleration data, calculated by the phase difference T _m, shifting the commanded acceleration data is a reference value in the time axis direction (Step S38), phase matching between actual acceleration data and command acceleration data is performed.

  In this example, a two-stage process is performed: a phase alignment process at a relatively coarse shift time interval ΔT in steps S21 to S28 and a phase alignment process at a fine time interval Δt in steps S29 to S38. Thus, the processing time is shortened, but the processing of step S29 to step S37 can be omitted by appropriately setting the time of ΔT to a fine time.

Next, the data calibration unit 6 performs a calibration actual position data calculation process shown in FIG. In this calibration actual position data calculation process, first, actual position data is calculated by performing second-order integration processing on the actual acceleration data (step S41). Next, after setting the counter i to an initial value of −20 (step S42), the sensitivity coefficient K _i is set to K _i = (1 + 0.01i) K (step S43), and the actual position data is adjusted. (Step S44). As described above, since the actual acceleration data is expressed as a product of the sensitivity coefficient K and the time function, the actual position data obtained by second-order integration is also expressed as a product of the sensitivity coefficient K and the time function. Is done. Therefore, the adjusted actual position data can be calculated by multiplying the actual position data by (1 + 0.01i) which is the ratio of K _i and K.

Then, to calculate the difference D _i between the adjustment actual position data and the command position data (step S45). The difference D _i, as shown in FIG. 9, a difference between the maximum value of the command position data and the maximum value of the adjustment actual position data D _a, or, a minimum of adjustment real position data and the minimum value of the command position data is the difference between the value D _b, or the difference d _a between the maximum value and the minimum value of the command position data, which is the difference between the difference d _b between the maximum value and the minimum value of the adjustment actual position data D _{c (=} d _a -d _b ). The differences D _a , D _b and D _c are all absolute values.

Then, the calculated difference _{D i} is determined whether or less predetermined reference value _{C c} (step S46), the difference _D if _i is less than the reference value _{C c} is the reference value _{C c} of the difference _{D i} (Step S47), the adjustment actual position data is stored as calibration actual position data (step S48), and then it is determined whether or not the difference D _i is equal to or less than a predetermined allowable value. (Step S49), if the difference D _i is less than or equal to the allowable value, the stored calibration actual position data is output. On the other hand, if it is determined in step S49 that the difference D _i is greater than the allowable value, and if it is determined in step S46 that the difference D _i exceeds the reference value C _c , the counter i is updated. (Step S52) Until the counter i exceeds 20 (Step S51), the processes of Steps S43 to S49 are repeated.

  The processes in steps S43 to S49 are processes for calibrating so that the difference between the actual position data and the command position data falls within a predetermined allowable range by adjusting the sensitivity coefficient K. This calibration process is performed. Thus, it is possible to calibrate the measurement error caused by the individual difference of the acceleration sensor 2 and the measurement error caused by the response characteristic changing depending on the use environment.

If the difference D _i falls within the allowable range, the adjusted actual position data is output as calibration actual position data (steps S49 and S50). If the difference D _i does not fall within the allowable range, the process is adjusted actual position data difference _{D i} is the minimum output as calibration actual position data (step S46, S50, S51).

The setting of the counter i (= −20 to 20) and the setting of the sensitivity coefficient K _i (= (1 + 0.01i) K) in the calibration process are merely examples, and are not limited to this example, and actual position data Is set as appropriate so that can be properly calibrated.

3. Motion Error Calculation Unit As shown in FIG. 3, the motion error calculation unit 7 receives the calibration actual position data calculated by the data calibration unit 6 (Step S8) and also receives the command position data (Step S8). S9), phase adjustment processing of the received calibration actual position data and command position data is performed (step S10). This phase alignment process is the same process as the process shown in FIG. 4 in the data calibration unit 6 and performs phase alignment using the command position data as a reference value. Note that the calibration actual position data calculated by the data calibration unit 6 has undergone an integration process and the like, and this process may cause a phase shift. The phase alignment process is performed. Note that the phase difference between the two is considered to be not so large at this time, so that only the processing of steps S29 to S38 shown in FIG. 4 may be performed.

  Next, the motion error calculation unit 7 calculates the difference between the calibration actual position data after phase alignment and the command position data (step S11), and then filters the obtained difference data to obtain motion error data. (Step S12). Since the difference data includes a fluctuation component of about 1 Hz, the fluctuation component is removed by a high-pass filter to obtain motion error data not including the fluctuation component. The motion error data obtained in this way is shown in FIG. 10A shows motion error data in the X-axis direction, and FIG. 10B shows motion error data in the Y-axis direction.

Next, the motion error calculation unit 7 differentiates the obtained motion error data to detect a portion indicating a change in the maximum, and the maximum value and the minimum value within the predetermined time width Wt including this are detected. By calculating the difference, the quadrant protrusion amounts P _X and P _Y are calculated (step S13). In the example shown in FIG. 10, P _X1 , P _X2 , P _Y1 , and P _Y2 are quadrant projection amounts in four quadrants. The quadrant protrusion is generated when the table 18 is reversed in each of the X-axis direction and the Y-axis direction, and the motion error data indicates a maximum change at the time of the reversal. , When the table 18 is recognized when the table 18 is inverted in each of the X-axis direction and the Y-axis direction, the predetermined time width Wt is set so as to include the inversion time, and the quadrant projection amount P _X , P _Y may be calculated.

Then, the motion error calculation unit 7 outputs the motion error data calculated as described above and the data related to the quadrant protrusion amounts P _X and P _Y to the display device 3, and these data are output by the display device 3. Appropriately displayed on the display unit.

[Measurement mode of motion error]
Next, an aspect in which the motion error of the table 18 of the machine tool 10 is measured using the motion error measuring device 1 having the above configuration will be described.

  First, the motion error measuring device 1 is fixed on the table 18. In this state, the numerical control device 20 numerically controls the feeding devices 17 and 19 to cause the table 18 to perform a circular motion for a plurality of cycles.

  Thereby, the acceleration in the X-axis direction and the Y-axis direction of the table 18 is detected by the acceleration sensor 2, and the detected data is processed by the data processing unit 4, so that the motion error and the quadrant projection amount of the table 18 are reduced. Calculated.

  That is, first, the actual acceleration data calculation unit 5 samples the voltage output from the acceleration sensor 2 at the same time interval as the command position data stored in the command position data storage unit 8, and has a predetermined sensitivity. After multiplying by the coefficient K, the averaged actual acceleration data for one cycle is calculated by averaging the obtained data.

Next, the data calibration unit 6 performs phase alignment between the command acceleration data obtained by performing the differential process on the command position data twice and the actual acceleration data, and then the second acceleration is used for the actual acceleration data after the phase alignment. D _a which is the difference between the actual position data obtained in this way and the command position data corresponding to the commanded acceleration data after phase matching, that is, the difference between the maximum value of the command position data and the maximum value of the adjusted actual position data, Or, D _b , which is the difference between the minimum value of the command position data and the minimum value of the adjustment actual position data, or the difference d _a between the maximum value and the minimum value of the command position data, and the maximum value and minimum of the adjustment actual position data The sensitivity coefficient K is adjusted so that D _c (= d _a −d _b ), which is a difference from the difference d _b , is within a predetermined allowable range, and the adjusted sensitivity coefficient K _i is obtained. Accordingly, the actual calibration position data is calculated.

  Next, the phase difference between the calibration actual position data and the command position data is performed by the motion error calculation unit 7 and the difference between the calibration actual position data after the phase alignment and the command position data is calculated. By filtering the data, motion error data is calculated, and the quadrant protrusion amount is calculated based on the motion error data.

  Then, the calculated motion error data and the data related to the quadrant projection amount are appropriately displayed on the display unit by the display device 3.

  Thus, according to the motion error measuring apparatus 1 of this example, by adjusting the sensitivity coefficient K, the difference between the actual position data obtained by second-order integration of the actual acceleration data and the command position data is Since the adjustment is made so as to be within a predetermined allowable range, an accurate actual position calibrated for a measurement error caused by an individual difference of the acceleration sensor 2 and a measurement error caused by a change in response characteristics depending on the use environment. Data can be obtained, and by comparing this with the command position data, the motion error of the table 18 can be calculated with higher accuracy than before.

  In addition, the motion error measuring device 1 of the present example has a configuration in which the acceleration sensor 2, the data processing unit 4, and the display device 3 are housed in one storage box, so that it can be carried and handled. Since it is easy and it is not necessary to connect to the numerical control device 20, it is possible to measure a motion error with a simple operation and to be used for a plurality of machine tools 1. There is also.

  As mentioned above, although the specific embodiment of the position of this invention was demonstrated, the aspect which this invention can take is not limited to this at all.

  For example, in the above example, the motion error calculation unit 7 performs the phase matching process (step S10). However, if the phase difference between the calibration actual position data and the command position data is small, this phase is particularly important. It is not necessary to perform the alignment process (step S10), and this may be omitted. Similarly, in the processing of the data calibration unit 6, if the phase difference between the actual acceleration data and the specified acceleration data is small, it is not necessary to perform the phase alignment processing (step S6), and this is omitted. You may do it.

  In addition, in the case where it is necessary to perform phase alignment between the data related to the detected acceleration and the data related to the command position in calculating the motion error, in this example, the data calibration unit 6 Phase alignment is performed with the commanded acceleration data obtained by differentiating the designated commanded position data twice (step S6), but after actual position data is calculated as shown in FIG. 11 (step S41). Then, phase matching processing may be performed (step S6), and thereafter processing for adjusting the sensitivity coefficient K may be performed (steps S42 to S49, S51, S52). In this case, the reference value in the phase matching process (step S6) is command position data.

  In the phase matching process (step S6), the reference value is shifted. However, the present invention is not limited to this, and the counterpart data whose phase is matched with the reference value may be shifted.

  In the above example, the command position data is stored in the command position data storage unit 8. However, the present invention is not limited to this, and wiring is necessary. However, the motion error measuring device 1 is connected to the numerical control device 20. The command position data may be acquired from the numerical controller 20.

  Further, the data processing unit 4 may be incorporated in the numerical controller 20. In this case, the acceleration sensor 2 is appropriately connected to the numerical control device 20 by wiring, and the display device 3 is also used as a display device provided in the machine tool 1. The acceleration sensor 2 may be embedded in the table 18 in advance.

  In the above example, the motion error of the table 18 is measured using the motion error measuring device 1, but the measurement target is not limited to this. For example, in the above example, the spindle head 13 Movement errors can also be measured.

DESCRIPTION OF SYMBOLS 1 Movement error measuring apparatus 2 Acceleration sensor 3 Display apparatus 4 Data processing part 5 Actual acceleration data calculation part 6 Data calibration part 7 Movement error calculation part 8 Command position data storage part 10 Machine tool 17 Feeder 18 Table 19 Feeder 20 Control apparatus

Claims (16)

A method for measuring a motion error of the motion unit in a positioning device having a feed device that moves the motion unit by one or more feed shafts and a numerical control device that numerically controls the feed device,
The numerical control device controls the feed axis of the feed device to move the operation unit to a command position according to a function of time for drawing a sine wave and output an acceleration sensor that detects the acceleration of the operation unit Sampling at predetermined time intervals, multiplying the obtained output data by a sensitivity coefficient, and calculating the actual acceleration data of the operating unit in the feed direction of the feed shaft,
The difference between the local maximum values, the local minimum values, or the difference between the local maximum value and the local minimum value in the actual position data obtained by second-order integration of the actual acceleration data and the command position data is determined in advance. A data calibration step of calculating calibration actual position data in which the sensitivity coefficient is adjusted so as to be within an allowable range;
A motion error measurement method comprising: a motion error calculation step of calculating a motion error of the operating unit by taking a difference between the calibration actual position data obtained in the data calibration step and the command position data. In the data calibration step,
Processing to match the phase of the command acceleration data obtained by second-order differentiation of the data related to the command position and the actual acceleration data;
The local maximum values, the local minimum values, or the local maximum values in the actual position data obtained by second-order integration of the actual acceleration data after phase alignment and the command position data corresponding to the command acceleration data after phase alignment. And a process of calculating calibration actual position data in which the sensitivity coefficient is adjusted so that a difference between a difference between a value and a minimum value falls within a predetermined allowable range. The motion error measuring method according to claim 1. In the data calibration step,
A process of calculating the actual position data by second-order integration of the actual acceleration data;
Processing to match the phase of the calculated actual position data and the command position data;
The difference between the local maximum values, the local minimum values, or the difference between the local maximum value and the local minimum value in the actual position data after phase alignment and the command position data is within a predetermined allowable range. The motion error measuring method according to claim 1, further comprising: processing for calculating calibration actual position data in which the sensitivity coefficient is adjusted.   In the motion error calculation step, the motion error of the operating unit is calculated by calculating a difference between the phase of the calibration actual position data and the command position data and the phase difference between the calibration actual position data and the command position data. The motion error measuring method according to any one of claims 1 to 3, wherein a process for calculating the motion error is executed.   5. The actual acceleration data is calculated by using an average value of the output data obtained by repeatedly operating the operating unit for a plurality of cycles in the actual speed data calculating step. Any of the motion error measurement methods described.   6. The motion error calculation step further includes: removing fluctuation components by processing the calculated motion error data using a high-pass filter. Movement error measurement method.   In the motion error calculation step, the amount of quadrant protrusion is calculated by taking the difference between the maximum value and the minimum value of the data within a predetermined time width, including the time zone indicating the maximum fluctuation in the calculated motion error data. 7. The motion error measuring method according to claim 1, wherein the motion error is calculated. A measuring device for measuring a motion error of the operation unit of a positioning device having a feed device that moves the operation unit by one or more feed axes and a numerical control device that numerically controls the feed device,
An acceleration sensor that is controlled by the numerical controller and detects an acceleration in the axial direction of the feed axis of the operating unit that moves to a command position according to a function of time for drawing a sine wave;
An actual acceleration data calculation unit that samples the output of the acceleration sensor at predetermined time intervals, multiplies the obtained output data by a sensitivity coefficient, and calculates actual acceleration data of the operation unit in the feed direction of the feed shaft; ,
The actual position data obtained by second-order integration of the actual acceleration data calculated by the actual acceleration data calculation unit, and the respective maximum values, or the minimum values, or the maximum value and the minimum value in the command position data, A data calibration unit that calculates calibration actual position data in which the sensitivity coefficient is adjusted so that the difference between the differences falls within a predetermined allowable range;
A motion error measurement comprising a motion error calculation unit that calculates a motion error of the motion unit by taking a difference between the calibration actual position data calculated by the data calibration unit and the command position data. apparatus. The data calibration unit is
Processing to match the phase of the command acceleration data obtained by second-order differentiation of the data related to the command position and the actual acceleration data calculated by the actual acceleration data calculation unit;
The local maximum values, the local minimum values, or the local maximum values in the actual position data obtained by second-order integration of the actual acceleration data after phase alignment and the command position data corresponding to the command acceleration data after phase alignment. And a process of calculating calibration actual position data in which the sensitivity coefficient is adjusted so that a difference between a difference between a value and a minimum value falls within a predetermined allowable range. The motion error measuring device according to claim 8. The data calibration unit is
A process of calculating the actual position data by second-order integration of the actual acceleration data;
Processing to match the phase of the calculated actual position data and the command position data;
The difference between the local maximum values, the local minimum values, or the difference between the local maximum value and the local minimum value in the actual position data after phase alignment and the command position data is within a predetermined allowable range. 9. The motion error measuring apparatus according to claim 8, wherein the apparatus is configured to execute a process of calculating calibration actual position data in which the sensitivity coefficient is adjusted.   The motion error calculation unit takes the difference between the calibration actual position data after the phase alignment and the command position data, and the motion error of the operation unit. The motion error measuring device according to claim 8, wherein the motion error measuring device is configured to execute a process for calculating the motion error.   The acceleration sensor, an actual acceleration data calculation unit, a data calibration unit, and a motion error calculation unit are housed in a storage box, and the storage box is configured to be detachable from the operation unit. The motion error measuring device according to any one of 8 to 11.   The said actual speed data calculation part is comprised so that the said actual acceleration data may be calculated using the average value of the said output data obtained by operating the said action | operation part over multiple cycles. The motion error measuring device according to any one of 8 to 12.   14. The motion error calculation unit is further configured to remove the fluctuation component by processing the calculated motion error data using a high-pass filter. Any motion error measuring device.   The movement error calculation unit further calculates a quadrant projection amount by taking a difference between a maximum value and a minimum value of data within a predetermined time width including a time zone indicating a maximum fluctuation in the calculated movement error data. 15. The motion error measuring device according to claim 8, wherein the motion error measuring device is configured to calculate.   16. A machine tool comprising a positioning device having a feeding device that moves an operation unit by one or more feeding shafts and a numerical control device that numerically controls the feeding device, wherein the machine tool is any one of claims 8 to 15. Machine tool equipped with a motion error measuring device.

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