Closed loop 1HCL

HighFreq

Using the 1HCL do i obtain a closed loop on the gcode? I mean does the 1HCL closed loop feeds the board and the board adjust the gcode execution based on the axis feedback?

dc42

@highfreq you need to run the tuning step and put the 1HCL board into closed loop mode. See https://docs.duet3d.com/User_manual/Tuning/Duet_3_1HCL_tuning. After that you use regular GCode commands.

Nightowl

@dc42
Have I got this right: Using the 1HCL obviates the need for stepper motor drivers to turn existing open loop stepper motors into closed loop?

Or am I being really optimistic?

dc42

@nightowl999 you need to use a stepper motor with an encoder so that the 1HCL board can read the position.

Nightowl

@dc42 Yep, optimism is my middle name. Sigh

dc42

@nightowl999 in future we may provide a board that can be used with a magnet on the back of the stepper motor to read the position.

Nightowl

@dc42 said in Closed loop 1HCL:

@nightowl999 in future we may provide a board that can be used with a magnet on the back of the stepper motor to read the position.

Well, if you ever need a CNC user to test stuff, just let me know!

HighFreq

@dc42 maybe my question was not clear, what i meant is, if the axis operates in closed loop than the board knows about it and avoids any following error? or the closed loop is only for the opertion of the axis.
Basicly if the board, for example, is making a circle and one axis is slightly behind does the board know it and slows down the other to keep the system in sync?

I think the tech term in english is "following error", does the 1HCL avoid it?

dc42

@highfreq what the closed loop bad does is monitor the actual position and adjust the motor current and phase to correct the position. For example, if the print head hits a blob or overhang or additional friction that stops the axis, the motor current will be increased to try to overcome it. If it cannot be overcome then an event is generated, which you can use e.g. to pause the print.

HighFreq

@dc42 maybe it is me not understanding, does the firmware use the closed loop to avoid chasing of axis? If a circle is made does the board monitor the axis in closed loop to make sure a circle is being made? This is the way all modern cnc machine controls work. It avoids chasing and the board knows at each moment where the axis are and adjust the feeding of gcode to avoid any chasing or desync of axis. Basicly if i tell the machine to make a circle than the board makes sure a circle is being made trough the feedback from axis, this is a gcode closed loop.

dc42

@highfreq the board monitors continuously (about 10k times per second) that the axis or extruder it is controlling is where it is supposed to be, so that it can attempt to correct for any error (by using more current than normal) and create an event if that fails. It does not slow other axes down in the way that you describe.

HighFreq

@dc42 so do you think i can put my controller in CL by emulating quadrature so that board knows where axis is at any time? By the manual can you understand if the quadrature emulation would be ok for 1HCL board?

thanks in advance.