docs: Added documentation for sweeping_vibrations resonance test method

Signed-off-by: Dmitry Butyugin <[email protected]>

docs/Config_Reference.md

@@ -1744,11 +1744,23 @@ section of the measuring resonances guide for more information on
 #   and on the toolhead (for X axis). These parameters have the same
 #   format as 'accel_chip' parameter. Only 'accel_chip' or these two
 #   parameters must be provided.
+#method: vibrations
+#   A test method to use for resonance testing. Valid choices are
+#   vibrations, sweeping_vibrations. The vibrations method tests
+#   different vibration frequencies at the designated test point.
+#   The sweeping_vibrations method tests different vibration frequencies
+#   while also moving the toolhead slowly around the test point, and
+#   thus may help, for example, if stiction of the toolhead (a force that
+#   must be be overcome to start toolhead motion) is too high.
+#   The default is vibrations, which is generally a recommended choice.
 #max_smoothing:
 #   Maximum input shaper smoothing to allow for each axis during shaper
 #   auto-calibration (with 'SHAPER_CALIBRATE' command). By default no
 #   maximum smoothing is specified. Refer to Measuring_Resonances guide
 #   for more details on using this feature.
+#move_speed: 50
+#   The speed (in mm/s) to move the toolhead to and between test points
+#   during the calibration. The default is 50.
 #min_freq: 5
 #   Minimum frequency to test for resonances. The default is 5 Hz.
 #max_freq: 133.33
@@ -1767,6 +1779,13 @@ section of the measuring resonances guide for more information on
 #   hz_per_sec. Small values make the test slow, and the large values
 #   will decrease the precision of the test. The default value is 1.0
 #   (Hz/sec == sec^-2).
+#motion_accel: 400
+#   An acceleration of slow moves. Available only for sweeping_vibrations
+#   test method. The default is 400 mm/sec^2.
+#motion_period: 1.2
+#   A period of slow moves. Must not be set to a too small value in order
+#   to not poison the measurements. Available only for sweeping_vibrations
+#   test method. The default is 1.2 sec which is a good all-round choice.
 ```
 
 ## Config file helpers

docs/Measuring_Resonances.md

@@ -691,6 +691,38 @@ 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.
 
+### Unreliable measurements of resonance frequencies
+
+Sometimes the resonance measurements can produce bogus results, leading to
+the incorrect suggestions for the input shapers. This can be caused by a
+variety of reasons, including running fans on the toolhead, incorrect
+position or non-rigid mounting of the accelerometer, or mechanical problems
+such as loose belts or binding or bumpy axis. Keep in mind that all fans
+should be disabled for resonance testing, especially the noisy ones, and
+that the accelerometer should be rigidly mounted on the corresponding
+moving part (e.g. on the bed itself for the bed slinger, or on the extruder
+of the printer itself and not the carriage, and some people get better
+results by mounting the accelerometer on the nozzle itself). As for
+mechanical problems, the user should inspect if there is any fault that
+can be fixed with a moving axis (e.g. linear guide rails cleaned up and
+lubricated and V-slot wheels tension adjusted correctly). However, if
+the axis has too high stiction (a force that must be be overcome to start
+toolhead motion over that axis) and thus binds, or if the user gets
+recommended shapers that do not eliminate the echo well on the prints
+and troubleshooting did not help, the user may try to use a different
+resonance test method that can be activated by adding
+```
+[resonance_tester]
+method: sweeping_vibrations
+```
+option to the Klipper config, restarting Klipper, and reruning the resonance
+test again. Note that this test moves the toolhead slowly around the test
+point, thus requiring some clearance around the test point over the tested
+axis. Since this method may produce higher amplitude vibrations compared to
+the default method, it is avised to monitor the printer closely during the
+test, and if the vibrations get too strong, the user may need to reduce
+`accel_per_hz` value in `[resonance_tester]` section from its default value.
+
 ### Testing custom axes
 
 `TEST_RESONANCES` command supports custom axes. While this is not really