kinematics: Generic Cartesian kinematics implementation (#6815)

* tests: Added a regression test for generic_cartesian kinematics

* kinematics: An intial implementation of generic_cartesian kinematics

* generic_cartesian: Refactored kinematics configuration API

* generic_cartesian: Use stepper instead of kinematic_stepper in configs

* generic_cartesian: Added SET_STEPPER_KINEMATICS command

* generic_cartesian: Fixed parsing of section names

* docs: Generic Caretsian kinematics documentation and config samples

* generic_cartesian: Implemented multi-mcu homing validation

* generic_cartesian: Fixed typos in docs, minor fixes

* generic_cartesian: Renamed `kinematics` option to `carriages`

* generic_cartesian: Moved kinematic_stepper.py file

* idex_modes: Internal refactoring of handling dual carriages

* stepper: Refactored the code to not store a reference to config object

* config: Updated example-generic-cartesian config

* generic_cartesian: Restricted SET_STEPPER_CARRIAGES and exported status

* idex_modes: Fixed handling stepper kinematics with input shaper enabled

* config: Updated configs and tests for SET_DUAL_CARRIAGE new params

* generic_cartesian: Avoid inheritance in the added classes

Signed-off-by: Dmitry Butyugin <dmbutyugin@google.com>

3 files changed, 286 insertions, 14 deletions

diff --git a/docs/Config_Reference.md b/docs/Config_Reference.md
index e65b79bf..f9ef676b 100644
--- a/docs/Config_Reference.md
+++ b/docs/Config_Reference.md
@@ -84,8 +84,9 @@ The printer section controls high level printer settings.
 [printer]
 kinematics:
 #   The type of printer in use. This option may be one of: cartesian,
-#   corexy, corexz, hybrid_corexy, hybrid_corexz, rotary_delta, delta,
-#   deltesian, polar, winch, or none. This parameter must be specified.
+#   corexy, corexz, hybrid_corexy, hybrid_corexz, generic_cartesian,
+#   rotary_delta, delta, deltesian, polar, winch, or none.
+#   This parameter must be specified.
 max_velocity:
 #   Maximum velocity (in mm/s) of the toolhead (relative to the
 #   print). This value may be changed at runtime using the
@@ -712,6 +713,172 @@ anchor_z:
 #   These parameters must be provided.
 ```
 
+### Generic Cartesian Kinematics
+
+See [example-generic-cartesian.cfg](../config/example-generic-caretesian.cfg)
+for an example generic Cartesian kinematics config file.
+
+This printer kinematic class allows a user to define in a pretty flexible
+manner an arbitrary Cartesian-style kinematics. In principle, the regular
+cartesian, corexy, hybrid_corexy can be defined this way too. However,
+more importantly, various otherwise unsupported kinematics such as
+inverted hybrid_corexy or corexyuv can be defined using this kinematic.
+
+Notably, the definition of a generic Cartesian kinematic deviates
+significantly from the other kinematic types. It follows the following
+convention: a user defines a set of carriages with certain range of motion
+that can move independently from each other (they should move over the
+Cartesian axes X, Y, and Z, hence the name of the kinematic) and
+corresponding endstops that allow the firmware to determine the position
+of carriages during homing, as well as a set of steppers that move those
+carriages. The `[printer]` section must specify the kinematic and
+other printer-level settings same as the regular Cartesian kinematic:
+```
+[printer]
+kinematics: generic_cartesian
+max_velocity:
+max_accel:
+#minimum_cruise_ratio:
+#square_corner_velocity:
+#max_accel_to_decel:
+#max_z_velocity:
+#max_z_accel:
+
+```
+
+Then a user must define the following three carriages: `[carriage x]`,
+`[carriage y]`, and `[carriage z]`, e.g.
+```
+[carriage x]
+endstop_pin:
+#   Endstop switch detection pin. If this endstop pin is on a
+#   different mcu than the stepper motor(s) moving this carriage,
+#   then it enables "multi-mcu homing". This parameter must be provided.
+#position_min: 0
+#   Minimum valid distance (in mm) the user may command the carriage to
+#   move to.  The default is 0mm.
+position_endstop:
+#   Location of the endstop (in mm). This parameter must be provided.
+position_max:
+#   Maximum valid distance (in mm) the user may command the stepper to
+#   move to. This parameter must be provided.
+#homing_speed: 5.0
+#   Maximum velocity (in mm/s) of the carriage when homing. The default
+#   is 5mm/s.
+#homing_retract_dist: 5.0
+#   Distance to backoff (in mm) before homing a second time during
+#   homing. Set this to zero to disable the second home. The default
+#   is 5mm.
+#homing_retract_speed:
+#   Speed to use on the retract move after homing in case this should
+#   be different from the homing speed, which is the default for this
+#   parameter
+#second_homing_speed:
+#   Velocity (in mm/s) of the carriage when performing the second home.
+#   The default is homing_speed/2.
+#homing_positive_dir:
+#   If true, homing will cause the carriage to move in a positive
+#   direction (away from zero); if false, home towards zero. It is
+#   better to use the default than to specify this parameter. The
+#   default is true if position_endstop is near position_max and false
+#   if near position_min.
+```
+
+Afterwards, a user specifies the stepper motors that move these carriages,
+for instance
+```
+[stepper my_stepper]
+carriages:
+#   A string describing the carriages the stepper moves. All defined
+#   carriages can be specified here, as well as their linear combinations,
+#   e.g. x, x+y, y-0.5*z, x-z, etc. This parameter must be provided.
+step_pin:
+dir_pin:
+enable_pin:
+rotation_distance:
+microsteps:
+#full_steps_per_rotation: 200
+#gear_ratio:
+#step_pulse_duration:
+```
+See [stepper](#stepper) section for more information on the regular
+stepper parameters. The `carriages` parameter defines how the stepper
+affects the motion of the carriages. For example, `x+y` indicates that
+the motion of the stepper in the positive direction by the distance `d`
+moves the carriages `x` and `y` by the same distance `d` in the positive
+direction, while `x-0.5*y` means the motion of the stepper in the positive
+direction by the distance `d` moves the carriage `x` by the distance `d`
+in the positive direction, but the carriage `y` will travel distance `d/2`
+in the negative direction.
+
+More than a single stepper motor can be defined to drive the same axis
+or belt. For example, on a CoreXY AWD setups two motors driving the same
+belt can be defined as
+```
+[carriage x]
+endstop_pin: ...
+...
+
+[carriage y]
+endstop_pin: ...
+...
+
+[stepper a0]
+carriages: x-y
+step_pin: ...
+dir_pin: ...
+enable_pin: ...
+rotation_distance: ...
+...
+
+[stepper a1]
+carriages: x-y
+step_pin: ...
+dir_pin: ...
+enable_pin: ...
+rotation_distance: ...
+...
+```
+with `a0` and `a1` steppers having their own control pins, but
+sharing the same `carriages` and corresponding endstops.
+
+There are situations when a user wants to have more than one endstop
+per axis. Examples of such configurations include Y axis driven by
+two independent stepper motors with belts attached to both ends of the
+X beam, with effectively two carriages on Y axis each having an
+independent endstop, and multi-stepper Z axis with each stepper having
+its own endstop (not to be confused with the configurations with
+multiple Z motors but only a single endstop). These configurations
+can be declared by specifying additional carriage(s) with their endstops:
+
+```
+[extra_carriage my_carriage]
+primary_carriage:
+#   The name of the primary carriage this carriage corresponds to.
+#   It also effectively defines the axis the carriage moves over.
+#   This parameter must be provided.
+endstop_pin:
+#   Endstop switch detection pin. This parameter must be provided.
+```
+
+and the corresponding stepper motors, for example:
+```
+[extra_carriage y1]
+primary_carriage: y
+endstop_pin: ...
+
+[stepper sy1]
+carriages: y1
+...
+```
+Notably, an `[extra_carriage]` does not define parameters such as
+`position_min`, `position_max`, and `position_endstop`, but instead
+inherits them from the specified `primary_carriage`, thus sharing
+the same range of motion with the primary carriage.
+
+For the references on how to configure IDEX setups, see the
+[dual carriage](#dual-carriage) section.
+
 ### None Kinematics
 
 It is possible to define a special "none" kinematics to disable
@@ -2207,8 +2374,8 @@ for an example configuration.
 
 ### [dual_carriage]
 
-Support for cartesian and hybrid_corexy/z printers with dual carriages
-on a single axis. The carriage mode can be set via the
+Support for cartesian, generic_cartesian and hybrid_corexy/z printers with
+dual carriages on a single axis. The carriage mode can be set via the
 SET_DUAL_CARRIAGE extended g-code command. For example,
 "SET_DUAL_CARRIAGE CARRIAGE=1" command will activate the carriage defined
 in this section (CARRIAGE=0 will return activation to the primary carriage).
@@ -2235,7 +2402,7 @@ typically be achieved with
 or a similar command.
 
 See [sample-idex.cfg](../config/sample-idex.cfg) for an example
-configuration.
+configuration with a regular Cartesian kinematic.
 
 ```
 [dual_carriage]
@@ -2249,7 +2416,7 @@ axis:
 #   error. If safe_distance is not provided, it will be inferred from
 #   position_min and position_max for the dual and primary carriages. If set
 #   to 0 (or safe_distance is unset and position_min and position_max are
-#   identical for the primary and dual carraiges), the carriages proximity
+#   identical for the primary and dual carriages), the carriages proximity
 #   checks will be disabled.
 #step_pin:
 #dir_pin:
@@ -2263,6 +2430,62 @@ axis:
 #   See the "stepper" section for the definition of the above parameters.
 ```
 
+For an example of dual carriage configuration with `generic_cartesian`
+kinematic, see the following configuration
+[sample](../config/example-generic-caretesian.cfg).
+Please note that in this case the `[dual_carriage]` configuration deviates
+from the configuration described above:
+```
+[dual_carriage my_dc_carriage]
+primary_carriage:
+#   Defines the matching primary carriage of this dual carriage and
+#   the corresponding IDEX axis. Valid choices are x, y, z.
+#   This parameter must be provided.
+#safe_distance:
+#   The minimum distance (in mm) to enforce between the dual and the primary
+#   carriages. If a G-Code command is executed that will bring the carriages
+#   closer than the specified limit, such a command will be rejected with an
+#   error. If safe_distance is not provided, it will be inferred from
+#   position_min and position_max for the dual and primary carriages. If set
+#   to 0 (or safe_distance is unset and position_min and position_max are
+#   identical for the primary and dual carriages), the carriages proximity
+#   checks will be disabled.
+endstop_pin:
+#position_min:
+position_endstop:
+position_max:
+#homing_speed:
+#homing_retract_dist:
+#homing_retract_speed:
+#second_homing_speed:
+#homing_positive_dir:
+...
+```
+Refer to [generic cartesian](#generic-cartesian) section for more information
+on the regular `carriage` parameters.
+
+Then a user must define one or more stepper motors moving the dual carriage
+(and other carriages as appropriate), for instance
+```
+[carriage x]
+...
+
+[carriage y]
+...
+
+[dual_carriage u]
+primary_carriage: x
+...
+
+[stepper dc_stepper]
+carriages: u-y
+...
+```
+
+It is worth noting that `generic_cartesian` kinematic can support two
+dual carriages for X and Y axes. For reference, see for instance a
+[sample](../config/sample-corexyuv.cfg) of CoreXYUV configuration.
+
 ### [extruder_stepper]
 
 Support for additional steppers synchronized to the movement of an
diff --git a/docs/G-Codes.md b/docs/G-Codes.md
index ae3ebc2b..b8a0ce69 100644
--- a/docs/G-Codes.md
+++ b/docs/G-Codes.md
@@ -341,15 +341,18 @@ The following command is available when the
 enabled.
 
 #### SET_DUAL_CARRIAGE
-`SET_DUAL_CARRIAGE CARRIAGE=[0|1] [MODE=[PRIMARY|COPY|MIRROR]]`:
+`SET_DUAL_CARRIAGE CARRIAGE=<carriage> [MODE=[PRIMARY|COPY|MIRROR]]`:
 This command will change the mode of the specified carriage.
-If no `MODE` is provided it defaults to `PRIMARY`. Setting the mode
-to `PRIMARY` deactivates the other carriage and makes the specified
-carriage execute subsequent G-Code commands as-is. `COPY` and `MIRROR`
-modes are supported only for `CARRIAGE=1`. When set to either of these
-modes, carriage 1 will then track the subsequent moves of the carriage 0
-and either copy relative movements of it (in `COPY` mode) or execute them
-in the opposite (mirror) direction (in `MIRROR` mode).
+If no `MODE` is provided it defaults to `PRIMARY`. `<carriage>` must
+reference a defined primary or dual carriage for `generic_cartesian`
+kinematics or be 0 (for primary carriage) or 1 (for dual carriage)
+for all other kinematics supporting IDEX. Setting the mode to `PRIMARY`
+deactivates the other carriage and makes the specified carriage execute
+subsequent G-Code commands as-is. `COPY` and `MIRROR` modes are supported
+only for dual carriages. When set to either of these modes, dual carriage
+will then track the subsequent moves of its primary carriage and either
+copy relative movements of it (in `COPY` mode) or execute them in the
+opposite (mirror) direction (in `MIRROR` mode).
 
 #### SAVE_DUAL_CARRIAGE_STATE
 `SAVE_DUAL_CARRIAGE_STATE [NAME=<state_name>]`: Save the current positions
@@ -715,6 +718,46 @@ is specified then the toolhead move will be performed with the given
 speed (in mm/s); otherwise the toolhead move will use the restored
 g-code speed.
 
+### [generic_cartesian]
+The commands in this section become automatically available when
+`kinematics: generic_cartesian` is specified as the printer kinematics.
+
+#### SET_STEPPER_CARRIAGES
+`SET_STEPPER_CARRIAGES STEPPER=<stepper_name> CARRIAGES=<carriages>
+[DISABLE_CHECKS=[0|1]]`: Set or update the stepper carriages.
+`<stepper_name>` must reference an existing stepper defined in `printer.cfg`,
+and `<carriages>` describes the carriages the stepper moves. See
+[Generic Cartesian Kinematics](Config_Reference.md#generic-cartesian-kinematics)
+for a more detailed overview of the `carriages` parameter in the
+stepper configuration section. Note that it is only possible
+to change the coefficients or signs of the carriages with this
+command, but a user cannot add or remove the carriages that the stepper
+controls.
+
+`SET_STEPPER_CARRIAGES` is an advanced tool, and the user is advised
+to exercise an extreme caution using it, since specifying incorrect
+configuration may physically damage the printer.
+
+Note that `SET_STEPPER_CARRIAGES` performs certain internal validations
+of the new printer kinematics after the change. Keep in mind that if it
+detects an issue, it may leave printer kinematics in an invalid state.
+This means that if `SET_STEPPER_CARRIAGES` reports an error, it is unsafe
+to issue other GCode commands, and the user must inspect the error message
+and either fix the problem, or manually restore the previous stepper(s)
+configuration.
+
+Since `SET_STEPPER_CARRIAGES` can update a configuration of a single
+stepper at a time, some sequences of changes can lead to invalid
+intermediate kinematic configurations, even if the final configuration
+is valid. In such cases a user can pass `DISABLE_CHECKS=1` parameters to
+all but the last command to disable intermediate checks. For example,
+if `stepper a` and `stepper b` initially have `x-y` and `x+y` carriages
+correspondingly, then the following sequence of commands will let a user
+effectively swap the carriage controls:
+`SET_STEPPER_CARRIAGES STEPPER=a CARRIAGES=x+y DISABLE_CHECKS=1`
+and `SET_STEPPER_CARRIAGES STEPPER=b CARRIAGES=x-y`, while
+still validating the final kinematics state.
+
 ### [hall_filament_width_sensor]
 
 The following commands are available when the
diff --git a/docs/Status_Reference.md b/docs/Status_Reference.md
index e8f7f2c0..0276c413 100644
--- a/docs/Status_Reference.md
+++ b/docs/Status_Reference.md
@@ -570,6 +570,12 @@ on a cartesian, hybrid_corexy or hybrid_corexz robot
 - `carriage_1`: The mode of the carriage 1. Possible values are:
   "INACTIVE", "PRIMARY", "COPY", and "MIRROR".
 
+On a `generic_cartesian` kinematic, the following information is
+available in `dual_carriage`:
+- `carriages["<carriage>"]`: The mode of the carriage `<carriage>`. Possible
+  values are "INACTIVE" and "PRIMARY" for the primary carriage and "INACTIVE",
+  "PRIMARY", "COPY", and "MIRROR" for the dual carriage.
+
 ## virtual_sdcard
 
 The following information is available in the