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docs: Limiting max_smoothing for input shaper autocalibration
Signed-off-by: Dmitry Butyugin <dmbutyugin@google.com>
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Dmitry Butyugin
KevinOConnor
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6 changed files with 108 additions and 22 deletions
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@ -168,22 +168,22 @@ recommended for your setup. For example:
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```
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Fitted shaper 'zv' frequency = 56.7 Hz (vibrations = 23.2%)
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Fitted shaper 'mzv' frequency = 52.9 Hz (vibrations = 10.9%)
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Fitted shaper 'ei' frequency = 62.0 Hz (vibrations = 8.9%)
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Fitted shaper '2hump_ei' frequency = 59.0 Hz (vibrations = 4.9%)
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Fitted shaper '3hump_ei' frequency = 65.0 Hz (vibrations = 3.3%)
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Recommended shaper is 2hump_ei @ 59.0 Hz
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Fitted shaper 'zv' frequency = 37.0 Hz (vibrations = 29.1%, smoothing ~= 0.115)
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Fitted shaper 'mzv' frequency = 35.4 Hz (vibrations = 15.9%, smoothing ~= 0.163)
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Fitted shaper 'ei' frequency = 42.0 Hz (vibrations = 15.1%, smoothing ~= 0.183)
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Fitted shaper '2hump_ei' frequency = 45.6 Hz (vibrations = 9.7%, smoothing ~= 0.260)
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Fitted shaper '3hump_ei' frequency = 59.0 Hz (vibrations = 7.5%, smoothing ~= 0.235)
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Recommended shaper is 3hump_ei @ 59.0 Hz
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```
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The suggested configuration can be added to `[input_shaper]` section of
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`printer.cfg`:
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`printer.cfg`, e.g.:
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```
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[input_shaper]
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shaper_freq_x: 59.0
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shaper_type_x: 2hump_ei
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shaper_freq_y: ...
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shaper_type_y: ...
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shaper_freq_x: ...
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shaper_type_x: ...
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shaper_freq_y: 59.0
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shaper_type_y: 3hump_ei
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```
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or you can choose some other configuration yourself based on the generated
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charts: peaks in the power spectral density on the charts correspond to
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@ -223,11 +223,82 @@ probe_points: ...
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Then the commands `TEST_RESONANCES AXIS=X` and `TEST_RESONANCES AXIS=Y`
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will use the correct accelerometer for each axis.
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## Max smoothing
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Keep in mind that the input shaper can create some smoothing in parts.
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Automatic tuning of the input shaper performed by `calibrate_shaper.py`
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script or `SHAPER_CALIBRATE` command tries not to exacerbate the smoothing,
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but at the same time they try to minimize the resulting vibrations.
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Sometimes they can make a sub-optimal choice of the shaper frequency, or
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maybe you simply prefer to have less smoothing in parts at the expense of
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a larger remaining vibrations. In these cases, you can request to limit
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the maximum smoothing from the input shaper.
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Let's consider the following results from the automatic tuning:
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```
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Fitted shaper 'zv' frequency = 62.2 Hz (vibrations = 36.9%, smoothing ~= 0.046)
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Fitted shaper 'mzv' frequency = 35.6 Hz (vibrations = 18.1%, smoothing ~= 0.161)
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Fitted shaper 'ei' frequency = 54.6 Hz (vibrations = 19.3%, smoothing ~= 0.108)
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Fitted shaper '2hump_ei' frequency = 46.2 Hz (vibrations = 9.2%, smoothing ~= 0.253)
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Fitted shaper '3hump_ei' frequency = 50.0 Hz (vibrations = 7.2%, smoothing ~= 0.328)
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Recommended shaper is 2hump_ei @ 46.2 Hz
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```
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Note that the reported `smoothing` values are some abstract projected values.
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These values can be used to compare different configurations: the higher the
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value, the more smoothing a shaper will create. However, these smoothing scores
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do not represent any real measure of smoothing, because the actual smoothing
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depends on [`max_accel`](#selecting-max-accel) and `square_corner_velocity`
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parameters. Therefore, you should print some test prints to see how much
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smoothing exactly a chosen configuration creates.
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In the example above the suggested shaper parameters are not bad, but what if
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you want to get less smoothing on the X axis? You can try to limit the maximum
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shaper smoothing using the following command:
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```
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~/klipper/scripts/calibrate_shaper.py /tmp/resonances_x_*.csv -o /tmp/shaper_calibrate_x.png --max_smoothing=0.2
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```
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which limits the smoothing to 0.2 score. Now you can get the following result:
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```
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Fitted shaper 'zv' frequency = 55.2 Hz (vibrations = 34.2%, smoothing ~= 0.057)
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Fitted shaper 'mzv' frequency = 33.8 Hz (vibrations = 17.4%, smoothing ~= 0.178)
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Fitted shaper 'ei' frequency = 47.4 Hz (vibrations = 17.6%, smoothing ~= 0.143)
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Fitted shaper '2hump_ei' frequency = 52.0 Hz (vibrations = 11.9%, smoothing ~= 0.200)
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Fitted shaper '3hump_ei' frequency = 75.0 Hz (vibrations = 9.7%, smoothing ~= 0.146)
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Recommended shaper is 3hump_ei @ 75.0 Hz
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```
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If you compare to the previously suggested parameters, the vibrations are a bit
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larger, but the smoothing is significantly smaller than previously.
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When deciding which `max_smoothing` parameter to choose, you can use a
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trial-and-error approach. Try a few different values and see which results
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you get. Note however that if you request the script to find a configuration
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for your printer with an unrealistically small smoothing, it will be unable
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to find a reasonable configuration. The suggested parameters will have a poor
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performance in this case and you can get too much remaining ringing as a result.
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So, always double-check the projected remaining vibrations and make sure they
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are not too high.
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Note that if you chose a good `max_smoothing` value for both of your axes, you
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can store it in the `printer.cfg` as
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```
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[resonance_tester]
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accel_chip: ...
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probe_points: ...
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max_smoothing: 0.25 # an example
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```
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Then, if you [rerun](#input-shaper-re-calibration) the input shaper auto-tuning
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using `SHAPER_CALIBRATE` Klipper command in the future, it will use the stored
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`max_smoothing` value as a reference.
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## Selecting max_accel
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Keep in mind that the input shaper can create some smoothing in parts,
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especially at high accelerations. Therefore, after the calibration
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is finished, you will still need to choose the `max_accel` value that
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Since the input shaper can create some smoothing in parts, especially at high
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accelerations, you will still need to choose the `max_accel` value that
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does not create too much smoothing in the printed parts. Follow
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[this](Resonance_Compensation.md#selecting-max_accel) part of
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the input shaper tuning guide and print the test model.
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@ -237,6 +308,10 @@ The same notice applies to the input shaper
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`SHAPER_CALIBRATE` command: it is still necessary to choose the right
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`max_accel` value after the auto-calibration.
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If you are doing a shaper re-calibration and the reported smoothing for the
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suggested shaper configuration is almost the same as what you got during the
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previous calibration, this step can be skipped.
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# Input Shaper auto-calibration
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