Joint following error and congifuration for delta robot

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9 years 7 months ago #88922 by Radek
Hi, I want to make a delta robot. I went through the stepconf, made simple programme in gcode and when I want to run simulation, there is "Joint 2 following error". I changed some parameters, like: ferror, min ferror, scale but it didn't help. What should I do ? What is more, in world mode I can't use "home axis". It's only possible in joint mode. Is it normal ?

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9 years 7 months ago #88963 by bkt
Code:
[AXIS_0] TYPE = ANGULAR HOME = 0.0 MAX_VELOCITY = 25.0 MAX_ACCELERATION = 750.0 STEPGEN_MAXACCEL = 937.5 SCALE = 80.0 FERROR = 1 MIN_FERROR = .25 MIN_LIMIT = -200.0 MAX_LIMIT = 200.0 HOME_OFFSET = 0.0 [AXIS_1] TYPE = ANGULAR HOME = 0.0 MAX_VELOCITY = 25.0 MAX_ACCELERATION = 750.0 STEPGEN_MAXACCEL = 937.5 SCALE = 80.0 FERROR = 1 MIN_FERROR = .25 MIN_LIMIT = -200.0 MAX_LIMIT = 200.0 HOME_OFFSET = 0.0 [AXIS_2] TYPE = ANGULAR HOME = 237.5 /********************* not same as axis1 and axis 0*****************/ MAX_VELOCITY = 100 /********************* not same as axis1 and axis 0*****************/ MAX_ACCELERATION = 200 /********************* not same as axis1 and axis 0*****************/ STEPGEN_MAXACCEL = 937.5 SCALE = 1 /********************* not same as axis1 and axis 0*****************/ FERROR = 10 /********************* not same as axis1 and axis 0*****************/ MIN_FERROR = 2 /********************* not same as axis1 and axis 0*****************/ MIN_LIMIT = -400 /********************* not same as axis1 and axis 0*****************/ <<<<<<<<< MAX_LIMIT = 400.0 /********************* not same as axis1 and axis 0*****************/<<<<<<<<<<<<<<< HOME_OFFSET = 0


if is delta with 3 only arms ..... must have the same parameter.
any how the line mark as "<<<<<<<<<<<<<<<<<" after comment in my experience if not use JA or newest master .... you must set very hight value .... because your kins not referring to degree limit but calculate it on cartesian space .... so not possible set a "real" degrees limit on machine.

If you use ja or master you can ....


regards
giorgio

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9 years 7 months ago #89094 by Radek
I made some changes and still have problem with joint 2

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9 years 7 months ago #89131 by andypugh
It might be easiest to modify an existing delta config to suit your actual machine.

There are sample configs for rotary and linear delta robots. Start LinuxCNC from the menu, then select either sim/axis/rdelta or sim/axis/ldelta and see if those behave as you expect (they won't move the hardware)

Homing is a joint-mode only thing. You home joints, not cartesian axes.

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9 years 7 months ago #89133 by Radek
I have linux 2.7.8 and there is no sample configuration for delta. I only found tripod, where type of axis is linear.
I think that this problem could have connection with capabilities of robot, maybe it can't move to given position?

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9 years 7 months ago #89136 by andypugh
For any kind of non-trivial kinematics I would strongly recommend moving to 2.8, even though it is technically a development version.

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9 years 7 months ago #89205 by Radek
Ok, I did that. Need to recognize in this config. If I come accross the problem, I'll write ;)

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9 years 7 months ago #89241 by Radek
@andypugh
What can I do with visualisation to avoid disappearing of delta? When I zoom out, there is only black monitor..

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9 years 7 months ago #89248 by andypugh
Can you see anything, with any of the Vismach configs?
It is possible that you have an OpenGL graphics problem.

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9 years 7 months ago #89250 by Radek
I managed to fix the visualisations by altering the rotarydelta config, but there seems to be another problem. When running the simple gcode through AXIS the end effector seems to be following the path correctly, but when i look at the vismach model the robot seems to be making a curved path, rather than a horizontal or vertical lines. Also, at the end of the gcode instructions, the end effector runs outside of workspace.

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