JP6074614B2 - Synchronous drive - Google Patents

Description

  The present invention relates to measurement of frequency characteristics in a synchronous drive device that drives one object in the same direction using a plurality of motors.

  A synchronous drive device that drives a single object in the same direction using multiple motors is used when a single motor has a line of force that does not pass through the center of gravity and a rotational moment is generated in the object. It is often used when there is a shortage.

  For example, in the case of an XY table in which the X axis for driving the head is driven by the Y axis, the X axis has a cantilever structure, and a rotational moment around the center of gravity of the X axis is generated when the Y axis is driven. Elasticity caused by the support structure causes a resonance phenomenon. At this time, by adopting a so-called gantry configuration in which both ends of the X axis are synchronously driven by the two Y1 and Y2 axes, the X axis can be moved in parallel without rotating around the center of gravity. Also, as an example of earning driving force, in a traveling cart that transports heavy objects such as liquid crystal panels and semiconductor wafers, if one motor drives the wheel and the torque is insufficient, such as two-wheel drive or four-wheel drive An example is given.

  Recently, servo motors are used as the motors that drive these. In adjusting the motor drive devices that drive these motors, it is important to know the frequency characteristics of the synchronous drive target for high-speed and high-precision control. It becomes.

  As a method for measuring this frequency characteristic, for example, as in Patent Document 1, a sweep sine wave command is input to a controller (motor drive device), the output of the motor (motor) is observed by a detector, and these inputs and outputs are In the case of a method of obtaining a resonance frequency that is a representative value of the frequency characteristic of a load by analyzing with a signal processor, or a device having a plurality of electric motors as in Patent Document 2, command to at least one controller There is a method of obtaining the resonance frequency of the machine from the result of observing the motor output of a plurality of axes.

JP 2003-134868 A JP 2004-215455 A

  However, the following problems arise when applying these frequency characteristic measurement methods to the synchronous drive device.

  First, when the frequency characteristic measurement method for one motor of Patent Document 1 is applied to a synchronous drive device as it is, for example, in the case of the XY table, the resonance phenomenon caused by the rotational moment around the center of gravity of the X axis is the Y1 axis or Y2 axis. It appears in the frequency characteristics.

In addition, when the method of Patent Document 2 is applied to an apparatus of a synchronous drive system, it is an implicit assumption that perfect synchrony between a plurality of axes is maintained even when measuring frequency characteristics. However, in the case of giving a command different from that at the time of synchronous driving and the frequency characteristic measurement executed by the control method, the axes are often asynchronous or can only be activated individually. If there is a deviation between multiple axes in the command input, response output is generated at a frequency of 1/2 times, 3/2 times, ..., (2n-1) / 2 times (n is a positive integer) of the reciprocal of the delay time. A false notch characteristic that cancels out appears, and a correct frequency characteristic during synchronous driving cannot be obtained. Furthermore, in Patent Document 2, various resonance frequency results can be obtained by various command input means and various response output combination means, but it is not possible to specify which characteristic coincides with the actual synchronous drive.

  The present invention solves the above-described conventional problems, and provides a means for correctly measuring frequency characteristics in a synchronous driving apparatus even when individual measurements are asynchronous even when the synchronous driving is actually performed.

In order to solve the above problem, the synchronous drive device according to claim 1 is a non-rotation command generator that pre-calculates non-rotation command inputs to a plurality of motor drive devices in which the rotational moment about the center of gravity of the object is zero. A command generator that gives the non-rotation command input to the motor drive device one at a time when measuring frequency characteristics, and a response memory that individually stores the motor response outputs to the non-rotation command input one by one An output corrector that corrects the delay time between the non-rotation command input and the response output to the non-rotation command input stored after the measurement is completed, and obtains a corrected output, and a plurality of corrected outputs for each motor. And a frequency analyzer that calculates frequency response characteristics from a command input to the motor drive device that directly drives the motor.

  Further, the synchronous drive device according to claim 2 uses the same M-sequence signal having the same average value 0 as a reference command as the non-rotation command input, changes only the amplitude by a plurality of motor drive devices, and rotates around the center of gravity. Is set to be zero.

  Further, in the synchronous drive device according to claim 3, the output corrector obtains a cross-correlation function between response outputs for the same non-rotation command input with respect to individually stored response outputs, and determines from the maximum or minimum value thereof. The delay time of the response output is determined, and the response output is corrected.

  According to the synchronous drive device of the first aspect, by using the non-rotation command input that does not rotate the synchronous drive target, the command response appears when the command input is given to the motor drive device one at a time. The resonance characteristics due to the rotational moment can be canceled by adding the corrected output by the frequency analyzer. Even in a motor drive device in which synchronization cannot be ensured, delay compensation by the output corrector works, so that it is possible to avoid distortion of frequency characteristics due to delay in measurement results.

  According to the synchronous drive device of the second aspect, the broadband frequency characteristic measurement can be measured in a short time by using the M-sequence signal.

  According to the synchronous drive device of the third aspect, even when the delay of the measurement result is unknown, the accurate delay time can be determined from the measurement data, and the reliability of the frequency characteristics can be ensured up to a high frequency.

Configuration diagram of synchronous drive device in the present invention Block diagram of a frequency characteristic analyzing apparatus and motor driving apparatus when measuring frequency characteristics in the present invention Timing chart of command input, response output and correction output of the present invention

(Embodiment 1)
First, a configuration diagram of the synchronous drive device shown in FIG. 1 will be described.

  A synchronous drive device having a gantry configuration is shown, and the X axis for directly driving the head is synchronously driven by two Y1 axes and Y2 axes. Each shaft is composed of a ball screw, a motor, a detector, and a motor driving device. At the time of synchronous driving, the motor driving device that has received a command input from the host controller drives the motor according to the command and returns a response output to the host controller by a detector that detects the motor state. The flow of these synchronization data is indicated by solid arrows.

  FIG. 2 shows a block diagram of the frequency characteristic analyzing apparatus and the motor driving apparatus when measuring the frequency characteristics.

  In the frequency characteristic analyzing apparatus 1, first, the non-rotation command generator 11 calculates a non-rotation command to the Y1 axis 41 and the Y2 axis 42 so that the moment around the center of gravity of the X axis 6 becomes zero. For example, when the center of gravity of the X axis 6 is on a line equidistant from the Y1 axis 41 and the Y2 axis 42, this non-rotation command can be realized by always driving the Y1 axis 41 and the Y2 axis 42 with the same torque. In addition, even when the center of gravity is biased to either direction, the distance between each axis and the center of gravity is multiplied by each axis torque command. A torque command may be set.

  In general, in frequency characteristic measurement, it is necessary to apply an input having a constant power over a wide range from a low frequency to a high frequency. Therefore, a sweep sine wave based on a sine wave in a constant frequency band or over the entire frequency range. An M-sequence signal having a characteristic close to uniform white noise is used as a command input. Also in this case, a non-rotation command in which the moment around the center of gravity of the X axis 6 is always zero can be generated by determining the amplitude according to the above policy.

  This non-rotation command is input to the command generator 12. The command generator 12 gives a non-rotation command one at a time to the motor drive device that drives synchronously. In the example of FIG. 2, since there are two motor drive devices that are synchronously driven, the Y1 axis component of the non-rotation command is given to the Y1 axis command generator 211, and 0 is given to the Y2 axis command generator 221; There are two patterns when 0 is given to the generator 211 and the Y2 axis component of the non-rotation command is given to the Y2 axis command generator 221.

  The response memory 13 individually stores two outputs of the Y1-axis detector 51 and the Y2-axis detector 52 for the command pattern applied by the command generator 12. Therefore, four types of responses are stored by combining the command input and the response output.

  A timing chart of command input and response storage is shown on the left side of FIG. In this example, it is assumed that the frequency characteristic measurement function for a single axis is used, so command generation to the Y1 axis and response measurement of the Y1 axis, and command generation to the Y2 axis and self axis response measurement of the Y2 axis are Think of it as completely synchronized. However, since the command generation to the Y1 axis and the response measurement of the Y2 axis, and the command generation to the Y2 axis and the response measurement of the Y1 axis are asynchronous between the axes, response output data can be obtained with different delay times each time. Become.

  The output corrector 14 corrects this delay time. When the non-rotation command and response output are different axes that require output correction as shown on the right side of FIG. 3, the response output data is advanced or delayed by the delay time, and 0 is added to the free time. Generate post-response output.

  As for the delay time, the difference in output timing between the command input for the Y1 axis and the command input for the Y2 axis may be measured by a timer or counter on the frequency characteristic analyzer side.

Further, by calculating a complementary correlation function that is a function of the delay time for the command synchronous response output and the command asynchronous response output corresponding to the same non-rotation command, the delay time can be estimated from the maximum value or the minimum value. It is also possible to determine whether the response output is inverted or non-inverted based on whether the absolute value of the complementary correlation function is the maximum or the minimum value.

  Finally, the frequency analyzer 15 adds the Y1 axis response output when the Y1 axis is non-inverting input, the output obtained by adding the Y1 axis corrected response output when the Y2 axis is non-inverting input, and the non-rotation command generator 11 Inputs obtained by adding the Y1-axis non-inversion command and the Y2-axis non-inversion command are individually subjected to FFT conversion, and the output FFT conversion result (complex number) is divided by the input FFT conversion result (complex number). The frequency characteristic can be accurately calculated.

  As described above, the synchronous drive device of the present invention provides a means for correctly measuring the frequency characteristics when the synchronous drive is actually synchronously driven, even when perfect synchronization is not obtained in each measurement. is there.

DESCRIPTION OF SYMBOLS 1 Frequency characteristic analyzer 11 Non-rotation command generator 12 Command generator 13 Response memory 14 Output corrector 15 Frequency analyzer 2 Motor drive device 21 Y1 axis motor drive device 211 Y1 axis command generator 212 Y1 axis response memory 22 Y2 axis motor drive device 221 Y2 axis command generator 222 Y2 axis response memory 3 Motor 31 Y1 axis motor 32 Y2 axis motor 4 Y axis 41 Y1 axis 42 Y2 axis 5 Detector 51 Y1 axis detector 52 Y2 axis detector 6 X axis

Claims (3)

A plurality of motors for driving the object body in the same direction, the plurality in the synchronous drive system including a plurality of motor drive device for controlling the respective motors of the plurality of motors, the center of gravity about the rotational moment of the object becomes 0 A non-rotation command generator that pre-calculates non-rotation command input to the motor drive device of the motor, and a command generator that gives the non-rotation command input to the motor drive devices one at a time when measuring frequency characteristics And a response storage device for individually storing the response outputs of the motor for the non-rotation command input one by one, and the response output for the non-rotation command input and the non-rotation command input stored after completion of the measurement. the motor delay and time correction to the corrected output corrector to obtain an output, and adding a plurality of corrected output for each of the motor, to drive the motor and this directly between the From the command input to the motor driving device, synchronous drive apparatus comprising: a frequency characteristic analyzer for calculating the frequency response characteristic. As the non-rotation command input, the same M-sequence signal having an average value of 0 is used as a reference command, and only the amplitude is changed by a plurality of motor driving devices so that the rotational moment around the center of gravity becomes zero. The synchronous drive device according to claim 1. The output corrector obtains a cross-correlation function between response outputs for the same non-rotation command input with respect to individually stored response outputs, determines a delay time of the response output from the maximum or minimum value, and outputs the response output. The synchronous drive device according to claim 1, wherein correction is performed.

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