are non cuboid soft limits possible?

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9 years 4 months ago #94795 by mechatroptik rainer
are non cuboid soft limits possible? was created by mechatroptik rainer
Hi,

There are two obstacles in my gantrymachine that I want to avoid to crash by some soft limit. This can't be done by using just min /max values of each individual axis in the ini-File. The forbidden space can be describe in the form "if Z is more than 123 then Y is not allowed to be less than 456"
Is there a way to do that?

Thank you in advance.

Regards
Rainer

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9 years 4 months ago #94797 by Todd Zuercher
Replied by Todd Zuercher on topic are non cuboid soft limits possible?
No, there is no provision for this in Linuxcnc. But that does not mean that it can't be done. I think that with some clever hal coding you could restrict movement to that area, but there still will be no pre-checking of moves (such as the warning you get when you load a file that exceeds a soft limit.)

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9 years 4 months ago #94799 by Todd Zuercher
Replied by Todd Zuercher on topic are non cuboid soft limits possible?
Something like this:
Code:
loadrt comp count=2 loadrt and2 count=1 loadrt message names=restricted.0 messages=Movement Restricted addf comp.0 servo-thread addf comp.1 servo-thread addf and2.0 servo-thread addf restricted.0 servo-thread setp comp.0.in0 123 setp comp.1.in0 456 net z-rest <=comp.0.out => and2.0.in0 net y-rest <=comp.1.out => and2.0.in1 net z-pos <= axis.2.joint-pos-cmd => comp.0.in1 net y-pos <= axis.1.joint-pos-cmd => comp.1.in1 net restrict <= and2.0.out => restricted.0.trigger => motion.feed-inhibit
This is only an example piece of code, it will need to be modified to fit in with your existing hal file.

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9 years 4 months ago #94806 by andypugh
Replied by andypugh on topic are non cuboid soft limits possible?
It _might_ work to restrict the joints as well as the axes, if it is the machine geometry that is the problem.

Otherwise some sort of HAL component to set feed-inhibit when outside the allowed polyhedron might work.

I have long thought that the axis limits should be optionally defined by an STL file.

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9 years 4 months ago #94812 by mechatroptik rainer
Replied by mechatroptik rainer on topic are non cuboid soft limits possible?
Thank you!

I'll Try Todds Idea.

Andy, I'm not sure if I understood you correctly. Machine geometrie is the problem in a ceratin sense. It's a gantry machine with trivial kinematics. But Y-Axis has additional contraints below a certain height.

Could that be solved by some trick in the kinematic description

Limits by STL would be great. I'm not sure how many ppl would actually use this.

Is it possible to draw additional lines in the axis 3D view? Like the wire-cuboid that visualizes machine limits.

Regards
Rainer

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9 years 4 months ago #94833 by andypugh
Replied by andypugh on topic are non cuboid soft limits possible?

mechatroptik rainer wrote: Andy, I'm not sure if I understood you correctly. Machine geometrie is the problem in a ceratin sense. It's a gantry machine with trivial kinematics. But Y-Axis has additional contraints below a certain height.


In that case joint contstraints won't work.

If you consider something like a delta robot the working volume is a wierd shape in XYZ space, but is a simple max and min limit for each joint.

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9 years 4 months ago #94938 by mechatroptik rainer
Replied by mechatroptik rainer on topic are non cuboid soft limits possible?
Hi,

it works!
My movement below a Z-Height of 129.7 mm is restricted to a Y-range between 24.9 mm and 473.7 mm

Here is the tested code.

Thank you again!

regards
Rainer
Code:
loadrt comp count=3 loadrt and2 count=2 loadrt or2 count=1 loadrt message names=restricted.0 messages="Movement Restricted" addf comp.0 servo-thread addf comp.1 servo-thread addf comp.2 servo-thread addf and2.0 servo-thread addf and2.1 servo-thread addf or2.0 servo-thread addf restricted.0 servo-thread setp comp.0.in1 129.7 setp comp.1.in1 24.9 setp comp.2.in0 473.7 net z-pos <= axis.2.joint-pos-cmd => comp.0.in0 net y-pos <= axis.1.joint-pos-cmd => comp.1.in0 => comp.2.in1 net z-rest <= comp.0.out => and2.0.in0 => and2.1.in0 net y-rest <= comp.1.out => and2.0.in1 net y-rest2 <= comp.2.out => and2.1.in1 net rest-ymin and2.0.out => or2.0.in1 net rest-ymax and2.1.out => or2.0.in0 net restrict <= or2.0.out => restricted.0.trigger => motion.feed-inhibit

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9 years 4 months ago #94945 by Todd Zuercher
Replied by Todd Zuercher on topic are non cuboid soft limits possible?
Thanks for posting your successful code for others to see.

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