JP6060384B2 - Motor drive device - Google Patents

Description

  The present invention relates to a motor drive device that receives a command from a host controller and performs motor control.

The host controller generates a command pattern for each command update cycle and transfers it to the motor drive device using a pulse train command, analog command, or network communication performed every communication cycle. The motor drive device controls the motor at a faster control cycle. The configuration of performing is very common in the FA market. (For example, Patent Document 1)
If the control cycle is shorter than the command update cycle, only the past command position can be obtained in the control cycle in which the command is not updated, so that periodic fluctuations occur every command update cycle. On the other hand, for example, in Patent Document 1, the difference between the position commands is taken at the command update cycle, and this is divided by the ratio between the command update cycle and the control cycle, and distributed to each control cycle between the command update cycles. .

JP 2006-113960 A

  However, in the conventional technique, it is assumed that the ratio between the command update period and the control period is known.

  In the case of a configuration in which the host controller and the motor drive device are synchronized using a communication network as in Patent Document 1, the ratio between the command update period and the control period is usually an integer, and refer to the settings related to communication synchronization. This can be known relatively easily.

  However, in the case of a configuration in which a command is transferred using a pulse train command or an analog command, the host controller and the motor drive device are asynchronous, and the command update cycle and control cycle are not disclosed in most cases. In addition, because of the versatility of the interface, there are many cases where the manufacturer of the host controller and the motor drive device are different, and there is no guarantee that the ratio between the command update cycle and the control cycle will be an integral multiple. Moreover, it is not easy to confirm the above in an actual site.

  The present invention solves the above-described conventional problems, and aims to accurately measure this even when the ratio between the command update cycle and the control cycle is unknown and to suppress periodic fluctuations every command update cycle. To do.

  In order to solve the above-described problem, the motor drive device according to claim 1 performs motor control according to a receiving unit that reads a command updated at each command update cycle from the host controller at each control cycle, and a reception unit output. From a differentiator that includes a control unit and that differentiates a command a certain number of times, a calculator that calculates an autocorrelation function with a delay time within a certain range with respect to the differencer output, and an identifier that identifies a command update period from the calculator output An estimator, and an interpolator that performs a process for suppressing periodic fluctuations for each command update period on the basis of the output of the estimator.

  The motor driving apparatus according to claim 2 is characterized in that the command is a position command and the difference number of the differentiator is two.

  The motor driving apparatus according to claim 3 is characterized in that the command is a speed command, and the difference number of the differentiator is one.

  According to a fourth aspect of the present invention, there is provided the motor drive device, wherein the upper limit of the delay time in the calculator is set to be shorter than a minimum repetition cycle assumed to include the command pattern.

  The motor drive apparatus according to claim 5 is characterized in that the identifier outputs, as a command update cycle, a minimum delay time in which the autocorrelation function as a calculator output exceeds a certain threshold value.

  In the motor drive device according to claim 6, the identifier calculates an autocorrelation function as a calculator output from a shorter delay time, and outputs a delay time that maximizes the autocorrelation function as a command update period. It is characterized by.

  The motor driving device according to claim 7 is characterized in that the interpolation unit is a moving average filter having a moving average time of a command update period.

  According to the motor drive device of the first aspect, even when the ratio between the command update period and the control period is not known, this can be estimated from the actual operation, and appropriate interpolation processing can be performed.

  According to the motor drive device of claim 2 and claim 3, by calculating an autocorrelation function in the dimension of acceleration with respect to the position command, the offset and drift components of the position and speed are eliminated, and the command is updated. The period can be identified more accurately.

  According to the motor drive apparatus of the fourth, fifth and sixth aspects, the command update period can be identified with appropriate accuracy and calculation time.

  According to the motor drive device of the seventh aspect, it is possible to perform appropriate command interpolation processing.

Block diagram of motor drive device in the present invention FIG. 4 is an example of command positions in the first embodiment. Diagram of an example of a one-time difference (command speed) of command positions in the first embodiment FIG. 6 is a diagram illustrating an example of a command position difference (command acceleration) twice in the first embodiment. FIG. 4 is a diagram illustrating an example of an autocorrelation function of commanded acceleration according to the first embodiment. Diagram of an example of a command speed after correction in the first embodiment

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
A configuration diagram of the motor drive device shown in FIG. 1 will be described.

  The host controller 1 sends command information to the motor drive device 2 at each command update period. The motor drive device 2 receives this command information at the receiving unit 21 and interpolates at the ratio of the command update cycle and the control cycle by the interpolation unit 22 to generate command information for each control cycle. This command information is input to the control unit 23, and control is performed so that the command matches the actual operation of the motor 3.

  The estimation unit 24 uses a differentiator 241 to difference the command, which is an output of the reception unit 21, for each control cycle by a certain number of times. The result is input to the calculator 242, and an autocorrelation function is calculated based on the multiplication result of the input shifted by a delay time that is an integral multiple of the control period. The identifier 243 identifies a delay time when the autocorrelation function is equal to or greater than the threshold value, and sets this as a command update period. This command update cycle is used as the output of the estimation unit 24 to pass to the interpolation unit 22 where command interpolation is performed using a moving average filter or command distribution processing.

  FIG. 2 shows an example of a command waveform received by the receiving unit 21 when a command position is given from the host controller 1. In this example, the command update cycle is 1 ms, the control cycle is 0.167 ms, which is 1/6, the maximum speed is 3000 r / min, the acceleration / deceleration time is 35 ms, the constant speed time is 45 ms, and the moving amount is 4 rotations. The position command of was shown. FIG. 2A is a graph showing the entire operation, and FIG. 2B is an enlarged view of the period from 0.02 s to 0.03 s at the start of acceleration. In the position dimension, the periodic variation due to the command update period is unclear, and it is difficult to visually determine this.

  FIG. 3 shows a waveform when the command position is differentiated once (command speed) by the differentiator 241.

  Periodic fluctuations that were difficult to understand in the position dimension appear at acceleration / deceleration at the command speed. FIG. 3 (a) shows the entire waveform of the command speed, and FIG. 3 (b) shows an enlarged waveform. In particular, in the acceleration / deceleration section, a step-like fluctuation synchronized with the command update period 1 ms is seen.

  FIG. 4 shows a waveform when the command position is differentiated twice (command acceleration) by the subtractor 241.

  In the dimension of acceleration, impulse-like commands are arranged in the acceleration / deceleration section as shown in FIG. 4A, and when it is enlarged in FIG.

  FIG. 5 shows the result of calculating the autocorrelation function of the commanded acceleration by the calculator 242. The autocorrelation function takes a range of ± 1 by normalization, but when the command acceleration has periodicity, it takes a value close to 1 for each cycle. Accordingly, the command update period can be identified by setting the threshold value around 0.8, for example, by the identifier 243 and searching for the minimum delay time for which the autocorrelation function exceeds this threshold value. FIG. 5A shows the entire waveform of the autocorrelation function, and FIG. 5B is an enlarged view up to a delay time of 10 ms. In this example, a peak exceeding the threshold value is obtained every 1 ms. The period can be identified as 1 ms.

  Since the peak value of the autocorrelation function varies depending on the command waveform, the autocorrelation function is calculated in order from the one with the shortest delay time instead of the judgment by the threshold value, and the point where the value becomes the maximum is used as the command update cycle Good. In this case, the calculation time can be shortened by terminating the calculation of the autocorrelation function here.

  In addition, when the command update cycle is shorter than the control cycle, no clear peak appears in the autocorrelation function, and calculation may continue to any extent. In order to avoid this, the upper limit of the delay time is determined from the minimum repetition period assumed to be included in the command pattern, and if there is no clear peak even if it is calculated up to that point, command interpolation is performed. By avoiding this, useless calculation can be omitted.

  FIG. 6 is a plot of filter output in the dimension of command speed when the interpolation unit 22 is a moving average filter and the moving average time is 1 ms of the command update period. 6A also shows that the stepped waveform in the corresponding acceleration / deceleration section shown in FIG. 3 is interpolated cleanly even when the enlarged waveform in FIG. 6B is seen.

  As described above, the motor drive device of the present invention provides means for accurately measuring the ratio of the command update cycle and the control cycle and suppressing periodic fluctuations for each command update cycle.

  Note that the estimation unit 24 described in the present invention does not necessarily have to be built in the motor drive device, but transfers command data received by the motor drive device to a personal computer or the like using a communication function (not shown), and a command update cycle estimation unit. The above process may be realized by software on a personal computer, and the estimation result may be transferred to the motor drive device again.

DESCRIPTION OF SYMBOLS 1 High-order controller 2 Motor drive device 21 Reception part 22 Interpolation part 23 Control part 24 Estimation part 241 Differencer 242 Calculator 243 Identifier 3 Motor

Claims (7)

In a motor drive device including a receiving unit that reads a command that is updated at each command update cycle from the host controller at each control cycle, and a control unit that performs motor control according to the output of the receiving unit, The estimator comprises an estimator consisting of a calculator that calculates the autocorrelation function with a delay time within a certain range with respect to the differencer output, and an identifier that identifies the command update period from the calculator output. A motor driving device comprising: an interpolation unit that performs a process for suppressing periodic fluctuations for each command update cycle for a command, and the motor is controlled by the control unit based on the output of the interpolation unit. The motor driving apparatus according to claim 1, wherein the command is a position command, and the number of differences of the differentiator is two. The motor driving apparatus according to claim 1, wherein the command is a speed command, and the difference count of the differentiator is one. The motor driving device according to claim 1, wherein the upper limit of the delay time in the calculator is set to be shorter than a minimum repetition period assumed to include the command pattern. The motor drive device according to claim 1, wherein the identifier outputs a minimum delay time in which an autocorrelation function as a calculator output exceeds a certain threshold as a command update period. 2. The motor according to claim 1, wherein the identifier calculates an autocorrelation function, which is a calculator output, from a shorter delay time, and outputs a delay time that maximizes the autocorrelation function as a command update period. Drive device. The motor driving apparatus according to claim 1, wherein the interpolation unit is a moving average filter in which a command update period output from the estimation unit is a moving average time.

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