Creating New Kinematics

[Tumblek]

Hello there,

I'm new here and enjoying grblHAL on Paul Barrett's board - thank you.

Please, can anyone point me to information about adding new kinematics from a grblHAL persepctive? I think I can work out / have worked out the actual maths.

The machine: In simplified terms, imagine a machine where the end of the vertical Z axis has a B axis that can move through an arc, say 90 degrees. So, when the B axis angle changes the Z will have to be moved up and down to compensate.

I want this to be in the firmware rather than repeatedly put into every GCode routine.

---

I have been taking time to look through and examine the existing ones such as Corexy, Wallplotter, Polar etc.

Initially I though that I could create a new kinematics setup by adding a setting option into config.h and then the new files (like Corexy.c). But I have seen that there are also mentions of "Corexy" in grblIb.c and grbl.h. I don't think these files should be altered and would prefer a "bolt-on" solution.

Also I've been looking to see how they relate to the struct in Kinematics.h....

void corexy_init (void)
{
    kinematics.limits_set_target_pos = corexy_limits_set_target_pos;
    kinematics.limits_get_axis_mask = corexy_limits_get_axis_mask;
    kinematics.limits_set_machine_positions = corexy_limits_set_machine_positions;
    kinematics.transform_from_cartesian = transform_from_cartesian;
    kinematics.transform_steps_to_cartesian = corexy_convert_array_steps_to_mpos;
    kinematics.segment_line = kinematics_segment_line;
    kinematics.homing_cycle_validate = homing_cycle_validate;
    kinematics.homing_cycle_get_feedrate = homing_cycle_get_feedrate;

    check_travel_limits = grbl.check_travel_limits;
    grbl.check_travel_limits = corexy_check_travel_limits;

    on_report_options = grbl.on_report_options;
    grbl.on_report_options = report_options;
}

Thank you for reading
Tumb

[terjeio]

Please, can anyone point me to information about adding new kinematics from a grblHAL persepctive?

The only information available are the current implementations in the kinematics folder, the simplest is the corexy code?
The easiest way to add one is to create a user plugin, name the init function my_plugin_init() and it will be called on startup automagically.
If compiling using the Arduino IDE there is no easy way to enable the API that I know of other than adding #define KINEMATICS_API somewhere in config.h. I have not checked v2 of the Arduino IDE so do not know if that allows you to define the symbol in the UI as a project setting.

[Tumblek]

Terje,
Thanks again. That is a great starting point for me. I will have a look.
I really appreciate those tips, as I know you are busy.
Best Wishes!