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Changes for page 07 Adjustments

Last modified by Iris on 2025/07/24 11:03
From version 22.1
edited by Karen
on 2023/05/15 14:54
Change comment: There is no comment for this version
To version 18.1
edited by Stone Wu
on 2022/09/23 14:44
Change comment: There is no comment for this version

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184 184  
185 185  The default current loop gain of the servo drive has ensured sufficient responsiveness. Generally, no adjustment is required. Only the position loop gain, speed loop gain and other auxiliary gains need to be adjusted.
186 186  
187 -This servo drive has two sets of gain parameters for position loop and speed loop. The user can switch the two sets of gain parameters according to the setting value of P02-07 the 2nd gain switching mode. The parameters are below.
187 +This servo drive has two sets of gain parameters for position loop and speed loop. The user can switch the two sets of gain parameters according to the setting value of P02-07 the 2nd gain switching mode. The parameters are are below.
188 188  
189 189  (% class="table-bordered" %)
190 190  |=(% scope="row" style="text-align: center; vertical-align: middle; width: 450px;" %)**Function code**|=(% style="text-align: center; vertical-align: middle; width: 751px;" %)**Name**
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342 342  
343 343  Table 7-10 Torque feedforward parameters
344 344  
345 -== **Model Tracking Control Function** ==
345 += **Mechanical resonance suppression** =
346 346  
347 -Model tracking control is suitable for position control mode, which adds a model loop outside the three loops. In the model loop, new position commands, speed feedforward and torque feedforward and other control quantities are generated according to the user's response requirements to the system and the ideal motor control model. Applying these control quantities to the actual control loop can significantly improve the response performance and positioning performance of the position control, the design block diagram is as follows:
347 +== Mechanical resonance suppression methods ==
348 348  
349 +When the mechanical rigidity is low, vibration and noise may occur due to resonance caused by shaft twisting, and it may not be possible to increase the gain setting. In this case, by using a notch filter to reduce the gain at a specific frequency, after resonance is effectively suppressed, you can continue to increase the servo gain. There are 2 methods to suppress mechanical resonance.
350 +
351 +**Torque instruction filter**
352 +
353 +By setting the filter time constant, the torque instruction is attenuated in the high frequency range above the cutoff frequency, so as to achieve the expectation of suppressing mechanical resonance. The cut-off frequency of the torque instruction filter could be calculated by the following formula:
354 +
349 349  (% style="text-align:center" %)
350 -(((
351 -(% class="wikigeneratedid img-thumbnail" style="display:inline-block" %)
352 -[[**Figure 7-7 Block Diagram of Model Tracking Control Design**>>image:20230515-7.png||id="20230515-7.png"]]
353 -)))
356 +[[image:image-20220706155820-5.jpeg||class="img-thumbnail"]]
354 354  
355 -The usage method and conditions of model tracking control:
358 +**Notch filter**
356 356  
357 -~1. Correctly set the inertia ratio of the system P3-1, which can be obtained by monitoring the real-time load inertia ratio of U0-20.
360 +The notch filter can achieve the expectation of suppressing mechanical resonance by reducing the gain at a specific frequency. When setting the notch filter correctly, the vibration can be effectively suppressed. You can try to increase the servo gain. The principle of the notch filter is shown in __Figure 7-3__.
358 358  
359 -2. Set the load rigidity level P3-2, set an appropriate value, it does not need to set a high rigidity level (recommended value 17~~21 under rigid load).
362 +== Notch filter ==
360 360  
361 -3. Set P2-20=1 to enable the function of model tracking control.
364 +The VD2 series servo drives have 2 sets of notch filters, each of which has 3 parameters, namely notch frequency, width grade and depth grade.
362 362  
363 -4. Adjust the P2-21 model tracking control gain from small to large, and gradually increase in steps of 1000 until the responsiveness of the system meets the actual demand. The responsiveness of the system is mainly determined by this parameter.
366 +**Width grade of notch filter**
364 364  
365 -5. After the responsiveness meets the requirements, user can adjust the parameters appropriately to increase the load rigidity level P3-2.
368 +The notch width grade is used to express the ratio of the notch width to the center frequency of the notch:
366 366  
367 -(% class="box infomessage" %)
370 +(% style="text-align:center" %)
371 +[[image:image-20220706155836-6.png||class="img-thumbnail"]]
372 +
373 +In formula (7-1), [[image:image-20220706155946-7.png]] is the center frequency of notch filter, that is, the mechanical resonance frequency; [[image:image-20220706155952-8.png]] is the width of notch filter, which represents the frequency bandwidth with an amplitude attenuation rate of **-3dB** relative to the center frequency of notch filter.
374 +
375 +**Depth grade of notch filter**
376 +
377 +The depth grade of notch filter represents the ratio relationship between input and output at center frequency.
378 +
379 +When the notch filter depth grade is 0, the input is completely suppressed at center frequency. When the notch filter depth grade is 100, the input is completely passable at center frequency. Therefore, the smaller the the notch filter depth grade is set, the deeper the the notch filter depth, and the stronger the suppression of mechanical resonance. But the system may be unstable, you should pay attention to it when using it. The specific relationship is shown in __Figure 7-4__.
380 +
381 +(% style="text-align:center" %)
368 368  (((
369 -**✎Note**: Model tracking control is only available in position mode, and cannot be used in other modes.
383 +(% class="wikigeneratedid img-thumbnail" style="display:inline-block" %)
384 +[[Figure 7-7 Notch characteristics, notch width, and notch depth>>image:image-20220608174259-3.png||id="Iimage-20220608174259-3.png"]]
370 370  )))
371 371  
387 +
388 +(% style="text-align:center" %)
389 +(((
390 +(% class="wikigeneratedid img-thumbnail" style="display:inline-block" %)
391 +[[Figure 7-8 Frequency characteristics of notch filter>>image:image-20220706160046-9.png||id="Iimage-20220706160046-9.png"]]
392 +)))
393 +
394 +
372 372  (% class="table-bordered" %)
373 -|=(% scope="row" style="text-align: center; vertical-align: middle; width: 120px;" %)**Function code**|=(% style="text-align: center; vertical-align: middle; width: 163px;" %)**Name**|=(% style="text-align: center; vertical-align: middle; width: 122px;" %)(((
396 +|=(% scope="row" style="text-align: center; vertical-align: middle; width: 113px;" %)**Function code**|=(% style="text-align: center; vertical-align: middle; width: 155px;" %)**Name**|=(% style="text-align: center; vertical-align: middle; width: 115px;" %)(((
374 374  **Setting method**
375 -)))|=(% style="text-align: center; vertical-align: middle; width: 128px;" %)(((
398 +)))|=(% style="text-align: center; vertical-align: middle; width: 121px;" %)(((
376 376  **Effective time**
377 -)))|=(% style="text-align: center; vertical-align: middle; width: 103px;" %)**Default value**|=(% style="text-align: center; vertical-align: middle; width: 107px;" %)**Range**|=(% style="text-align: center; vertical-align: middle; width: 321px;" %)**Definition**|=(% style="text-align: center; vertical-align: middle;" %)**Unit**
378 -|=(% style="text-align: center; vertical-align: middle; width: 120px;" %)P2-20|(% style="text-align:center; vertical-align:middle; width:163px" %)Model tracking control function|(% style="text-align:center; vertical-align:middle; width:122px" %)(((
379 -Shutdown setting
380 -)))|(% style="text-align:center; vertical-align:middle; width:128px" %)(((
400 +)))|=(% style="text-align: center; vertical-align: middle; width: 99px;" %)**Default value**|=(% style="text-align: center; vertical-align: middle; width: 102px;" %)**Range**|=(% style="text-align: center; vertical-align: middle; width: 362px;" %)**Definition**|=(% style="text-align: center; vertical-align: middle; width: 96px;" %)**Unit**
401 +|=(% style="text-align: center; vertical-align: middle; width: 113px;" %)P04-05|(% style="text-align:center; vertical-align:middle; width:155px" %)1st notch filter frequency|(% style="text-align:center; vertical-align:middle; width:115px" %)(((
402 +Operation setting
403 +)))|(% style="text-align:center; vertical-align:middle; width:121px" %)(((
381 381  Effective immediately
382 -)))|(% style="text-align:center; vertical-align:middle; width:103px" %)0|(% style="text-align:center; vertical-align:middle; width:107px" %)0 to 1|When the function code is set to 1, enable the model tracking control function.|
383 -|=(% style="text-align: center; vertical-align: middle; width: 120px;" %)P2-21|(% style="text-align:center; vertical-align:middle; width:163px" %)Model tracking  control gain|(% style="text-align:center; vertical-align:middle; width:122px" %)(((
384 -Shutdown setting
385 -)))|(((
405 +)))|(% style="text-align:center; vertical-align:middle; width:99px" %)300|(% style="text-align:center; vertical-align:middle; width:102px" %)250 to 5000|(% style="width:362px" %)Set the center frequency of the 1st notch filter. When the set value is 5000, the function of notch filter is invalid.|(% style="text-align:center; vertical-align:middle; width:96px" %)Hz
406 +|=(% style="text-align: center; vertical-align: middle; width: 113px;" %)P04-06|(% style="text-align:center; vertical-align:middle; width:155px" %)1st notch filter depth|(% style="text-align:center; vertical-align:middle; width:115px" %)(((
407 +Operation setting
408 +)))|(% style="text-align:center; vertical-align:middle; width:121px" %)(((
386 386  Effective immediately
387 -)))|(% style="text-align:center; vertical-align:middle; width:103px" %)1000|(% style="text-align:center; vertical-align:middle; width:107px" %)200 to 20000|(% rowspan="2" %)(% style="width:321px" %)Increasing the model tracking control gain can improve the position response performance of the model loop. If the gain is too high, it may cause overshoot behavior. The gain compensation affects the damping ratio of the model loop, and the damping ratio becomes larger as the gain compensation becomes larger.|(% style="text-align:center; vertical-align:middle" %)0.1/s
388 -
389 -|=(% style="text-align: center; vertical-align: middle; width: 120px;" %)P2-22|(% style="text-align:center; vertical-align:middle; width:163px" %)Model tracking control gain compensation|Shutdown setting|(((
410 +)))|(% style="text-align:center; vertical-align:middle; width:99px" %)100|(% style="text-align:center; vertical-align:middle; width:102px" %)0 to 100|(% style="width:362px" %)(((
411 +1. 0: all truncated
412 +1. 100: all passed
413 +)))|(% style="text-align:center; vertical-align:middle; width:96px" %)-
414 +|=(% style="text-align: center; vertical-align: middle; width: 113px;" %)P04-07|(% style="text-align:center; vertical-align:middle; width:155px" %)1st notch filter width|(% style="text-align:center; vertical-align:middle; width:115px" %)(((
415 +Operation setting
416 +)))|(% style="text-align:center; vertical-align:middle; width:121px" %)(((
390 390  Effective immediately
391 -)))|1000|(% style="text-align:center; vertical-align:middle; width:107px" %)500 to 2000|(% style="text-align:center; vertical-align:middle" %)0.10%
392 -
393 -(% class="table-bordered" %)
394 -|=(% scope="row" style="text-align: center; vertical-align: middle; width: 120px;" %)**Function code**|=(% style="text-align: center; vertical-align: middle; width: 163px;" %)**Name**|=(% style="text-align: center; vertical-align: middle; width: 122px;" %)(((
395 -**Setting method**
396 -)))|=(% style="text-align: center; vertical-align: middle; width: 128px;" %)(((
397 -**Effective time**
398 -)))|=(% style="text-align: center; vertical-align: middle; width: 103px;" %)**Default value**|=(% style="text-align: center; vertical-align: middle; width: 107px;" %)**Range**|=(% style="text-align: center; vertical-align: middle; width: 321px;" %)**Definition**|=(% style="text-align: center; vertical-align: middle;" %)**Unit**
399 -|=(% style="text-align: center; vertical-align: middle; width: 120px;" %)P2-23|(% style="text-align:center; vertical-align:middle; width:163px" %)Model tracking control forward rotation bias|(((
418 +)))|(% style="text-align:center; vertical-align:middle; width:99px" %)4|(% style="text-align:center; vertical-align:middle; width:102px" %)0 to 12|(% style="width:362px" %)(((
419 +1. 0: 0.5 times the bandwidth
420 +1. 4: 1 times the bandwidth
421 +1. 8: 2 times the bandwidth
422 +1. 12: 4 times the bandwidth
423 +)))|(% style="text-align:center; vertical-align:middle; width:96px" %)-
424 +|=(% style="text-align: center; vertical-align: middle; width: 113px;" %)P04-08|(% style="text-align:center; vertical-align:middle; width:155px" %)2nd notch filter frequency|(% style="text-align:center; vertical-align:middle; width:115px" %)(((
400 400  Operation setting
401 -)))|(((
426 +)))|(% style="text-align:center; vertical-align:middle; width:121px" %)(((
402 402  Effective immediately
403 -)))|(% style="text-align:center; vertical-align:middle; width:103px" %)1000|(% style="text-align:center; vertical-align:middle; width:107px" %)0 to 10000|(% rowspan="2" %)(% style="width:321px" %)Torque feedforward size in the positive and reverse direction under model tracking control|(% style="text-align:center; vertical-align:middle" %)0.10%
404 -|=(% style="text-align: center; vertical-align: middle; width: 120px;" %)P2-24|(% style="text-align:center; vertical-align:middle; width:163px" %)Model tracking control reverses rotation bias|(((
428 +)))|(% style="text-align:center; vertical-align:middle; width:99px" %)500|(% style="text-align:center; vertical-align:middle; width:102px" %)250 to 5000|(% style="width:362px" %)Set the center frequency of the 2nd notch filter. When the set value is 5000, the function of the notch filter is invalid.|(% style="text-align:center; vertical-align:middle; width:96px" %)Hz
429 +|=(% style="text-align: center; vertical-align: middle; width: 113px;" %)P04-09|(% style="text-align:center; vertical-align:middle; width:155px" %)2nd notch filter depth|(% style="text-align:center; vertical-align:middle; width:115px" %)(((
405 405  Operation setting
406 -)))|(((
431 +)))|(% style="text-align:center; vertical-align:middle; width:121px" %)(((
407 407  Effective immediately
408 -)))|1000|(% style="text-align:center; vertical-align:middle; width:107px" %)0 to 10000|0.10%
409 -|=(% style="text-align: center; vertical-align: middle; width: 120px;" %)P2-25|(% style="text-align:center; vertical-align:middle; width:163px" %)Model tracking control speed feedforward compensation|Operation setting|(((
433 +)))|(% style="text-align:center; vertical-align:middle; width:99px" %)100|(% style="text-align:center; vertical-align:middle; width:102px" %)0 to 100|(% style="width:362px" %)(((
434 +1. 0: all truncated
435 +1. 100: all passed
436 +)))|(% style="text-align:center; vertical-align:middle; width:96px" %)-
437 +|=(% style="text-align: center; vertical-align: middle; width: 113px;" %)P04-10|(% style="text-align:center; vertical-align:middle; width:155px" %)2nd notch filter width|(% style="text-align:center; vertical-align:middle; width:115px" %)(((
438 +Operation setting
439 +)))|(% style="text-align:center; vertical-align:middle; width:121px" %)(((
410 410  Effective immediately
411 -)))|(% style="text-align:center; vertical-align:middle; width:103px" %)1000|(% style="text-align:center; vertical-align:middle; width:107px" %)0 to 10000|(% style="width:321px" %)The size of the speed feedforward under model tracking control|(% style="text-align:center; vertical-align:middle" %)0.10%
441 +)))|(% style="text-align:center; vertical-align:middle; width:99px" %)4|(% style="text-align:center; vertical-align:middle; width:102px" %)0 to 12|(% style="width:362px" %)(((
442 +1. 0: 0.5 times the bandwidth
443 +1. 4: 1 times the bandwidth
444 +1. 8: 2 times the bandwidth
445 +1. 12: 4 times the bandwidth
446 +)))|(% style="text-align:center; vertical-align:middle; width:96px" %)-
412 412  
413 -Please refer to the following for an example of the procedure of adjusting servo gain.
414 -
415 -|**Step**|** Content**
416 -|1|Please try to set the correct load inertia ratio parameter P3-1.
417 -|2|If the automatic adjustment mode is used (P3-3 is set to 0), please set the basic rigidity level parameter P3-2. If in manual adjustment mode (P3-3 is set to 1), please set the gain P2-1~~P2-3 related to the position loop and speed loop and the torque filter time constant P4-4. The setting principle is mainly no vibration and overshoot.
418 -|3|Turn on the model tracking function, set P2-20 to 1.
419 -|4|Increase the model tracking gain P2-21 within the range of no overshoot and vibration occurring.
420 -|5|If the rigidity level of step 2 is set relatively low, user can properly increase the rigidity level P3-2.
421 -|6|When overshoot occurs, or the responses of forward rotation and reverse rotation are different, user can fine-tune through model tracking control forward bias P2-23, model tracking control reverse bias P2-24, model tracking control speed feedforward compensation P2 -25.
448 +Table 7-11 Notch filter function code parameters
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