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Diffstat (limited to 'docs/Measuring_Resonances.md')
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1 files changed, 89 insertions, 14 deletions
diff --git a/docs/Measuring_Resonances.md b/docs/Measuring_Resonances.md index 9efa16ca..7dbd5938 100644 --- a/docs/Measuring_Resonances.md +++ b/docs/Measuring_Resonances.md @@ -168,22 +168,22 @@ recommended for your setup. For example:  ``` -Fitted shaper 'zv' frequency = 56.7 Hz (vibrations = 23.2%) -Fitted shaper 'mzv' frequency = 52.9 Hz (vibrations = 10.9%) -Fitted shaper 'ei' frequency = 62.0 Hz (vibrations = 8.9%) -Fitted shaper '2hump_ei' frequency = 59.0 Hz (vibrations = 4.9%) -Fitted shaper '3hump_ei' frequency = 65.0 Hz (vibrations = 3.3%) -Recommended shaper is 2hump_ei @ 59.0 Hz +Fitted shaper 'zv' frequency = 37.0 Hz (vibrations = 29.1%, smoothing ~= 0.115) +Fitted shaper 'mzv' frequency = 35.4 Hz (vibrations = 15.9%, smoothing ~= 0.163) +Fitted shaper 'ei' frequency = 42.0 Hz (vibrations = 15.1%, smoothing ~= 0.183) +Fitted shaper '2hump_ei' frequency = 45.6 Hz (vibrations = 9.7%, smoothing ~= 0.260) +Fitted shaper '3hump_ei' frequency = 59.0 Hz (vibrations = 7.5%, smoothing ~= 0.235) +Recommended shaper is 3hump_ei @ 59.0 Hz ``` The suggested configuration can be added to `[input_shaper]` section of -`printer.cfg`: +`printer.cfg`, e.g.: ``` [input_shaper] -shaper_freq_x: 59.0 -shaper_type_x: 2hump_ei -shaper_freq_y: ... -shaper_type_y: ... +shaper_freq_x: ... +shaper_type_x: ... +shaper_freq_y: 59.0 +shaper_type_y: 3hump_ei ``` or you can choose some other configuration yourself based on the generated charts: peaks in the power spectral density on the charts correspond to @@ -223,11 +223,82 @@ probe_points: ... Then the commands `TEST_RESONANCES AXIS=X` and `TEST_RESONANCES AXIS=Y` will use the correct accelerometer for each axis. +## Max smoothing + +Keep in mind that the input shaper can create some smoothing in parts. +Automatic tuning of the input shaper performed by `calibrate_shaper.py` +script or `SHAPER_CALIBRATE` command tries not to exacerbate the smoothing, +but at the same time they try to minimize the resulting vibrations. +Sometimes they can make a sub-optimal choice of the shaper frequency, or +maybe you simply prefer to have less smoothing in parts at the expense of +a larger remaining vibrations. In these cases, you can request to limit +the maximum smoothing from the input shaper. + +Let's consider the following results from the automatic tuning: + + +``` +Fitted shaper 'zv' frequency = 62.2 Hz (vibrations = 36.9%, smoothing ~= 0.046) +Fitted shaper 'mzv' frequency = 35.6 Hz (vibrations = 18.1%, smoothing ~= 0.161) +Fitted shaper 'ei' frequency = 54.6 Hz (vibrations = 19.3%, smoothing ~= 0.108) +Fitted shaper '2hump_ei' frequency = 46.2 Hz (vibrations = 9.2%, smoothing ~= 0.253) +Fitted shaper '3hump_ei' frequency = 50.0 Hz (vibrations = 7.2%, smoothing ~= 0.328) +Recommended shaper is 2hump_ei @ 46.2 Hz +``` +Note that the reported `smoothing` values are some abstract projected values. +These values can be used to compare different configurations: the higher the +value, the more smoothing a shaper will create. However, these smoothing scores +do not represent any real measure of smoothing, because the actual smoothing +depends on [`max_accel`](#selecting-max-accel) and `square_corner_velocity` +parameters. Therefore, you should print some test prints to see how much +smoothing exactly a chosen configuration creates. + +In the example above the suggested shaper parameters are not bad, but what if +you want to get less smoothing on the X axis? You can try to limit the maximum +shaper smoothing using the following command: +``` +~/klipper/scripts/calibrate_shaper.py /tmp/resonances_x_*.csv -o /tmp/shaper_calibrate_x.png --max_smoothing=0.2 +``` +which limits the smoothing to 0.2 score. Now you can get the following result: + + +``` +Fitted shaper 'zv' frequency = 55.2 Hz (vibrations = 34.2%, smoothing ~= 0.057) +Fitted shaper 'mzv' frequency = 33.8 Hz (vibrations = 17.4%, smoothing ~= 0.178) +Fitted shaper 'ei' frequency = 47.4 Hz (vibrations = 17.6%, smoothing ~= 0.143) +Fitted shaper '2hump_ei' frequency = 52.0 Hz (vibrations = 11.9%, smoothing ~= 0.200) +Fitted shaper '3hump_ei' frequency = 75.0 Hz (vibrations = 9.7%, smoothing ~= 0.146) +Recommended shaper is 3hump_ei @ 75.0 Hz +``` + +If you compare to the previously suggested parameters, the vibrations are a bit +larger, but the smoothing is significantly smaller than previously. + +When deciding which `max_smoothing` parameter to choose, you can use a +trial-and-error approach. Try a few different values and see which results +you get. Note however that if you request the script to find a configuration +for your printer with an unrealistically small smoothing, it will be unable +to find a reasonable configuration. The suggested parameters will have a poor +performance in this case and you can get too much remaining ringing as a result. +So, always double-check the projected remaining vibrations and make sure they +are not too high. + +Note that if you chose a good `max_smoothing` value for both of your axes, you +can store it in the `printer.cfg` as +``` +[resonance_tester] +accel_chip: ... +probe_points: ... +max_smoothing: 0.25 # an example +``` +Then, if you [rerun](#input-shaper-re-calibration) the input shaper auto-tuning +using `SHAPER_CALIBRATE` Klipper command in the future, it will use the stored +`max_smoothing` value as a reference. + ## Selecting max_accel -Keep in mind that the input shaper can create some smoothing in parts, -especially at high accelerations. Therefore, after the calibration -is finished, you will still need to choose the `max_accel` value that +Since the input shaper can create some smoothing in parts, especially at high +accelerations, you will still need to choose the `max_accel` value that does not create too much smoothing in the printed parts. Follow [this](Resonance_Compensation.md#selecting-max_accel) part of the input shaper tuning guide and print the test model. @@ -237,6 +308,10 @@ The same notice applies to the input shaper `SHAPER_CALIBRATE` command: it is still necessary to choose the right `max_accel` value after the auto-calibration. +If you are doing a shaper re-calibration and the reported smoothing for the +suggested shaper configuration is almost the same as what you got during the +previous calibration, this step can be skipped. + # Input Shaper auto-calibration |