Re: [Emc-users] problem with genserkins

[Viesturs L. <vie...@gm...>]

2011/11/17 Francesca Sca <fan...@ya...>:
>
>
> Viesturs wrote:
>
>>Yes, that is correct. Genserkins does calcs for 6 joints. If the
>>actual robot has fewer, then dummy joints need to be defined to make
>>up 6 joints for genserkins.
>
>
> How I can make an axis dummy? for example the C one?

I think - define DH parameters so that it matches the actual
orientation of Your tool and do not attach any pwmgen/stepgen to it.


>>You did not answer, how You want to operate the gripper (just
>>open/close or control, how much and how fast does it grab), so it is
>>hard to tell, if that can be done in HAL.
>>Sorry, I cannot help with genserkins, because I myself need help with
>>the genserkins :))
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>
> Both the ways are ok for me. I think that I could control the axis that moves the fingers separatly from kinematic genserkins, I would have problems anymore.

Then there is very nice way to solve it:
Use mux2 and limit3 components:
Mux2.sel pin should be the open/close command (can be driven from
g-code, if linked to spindle or coolant on/off HAL pins), mux2.in0 and
mux2.in1 should be stepgen positions, when gripper is closed and open.
Link mux2.out to limit3 input, set acceleration and velocity limits in
limit3 and link limit3 output to stepgen pos-cmd input.

> Genserkins is a nice problem for many people :p

No, I think You are wrong.
Genserkins is extremely powerful, where it is applicable. I would say
that genserkins is the reason, why EMC can beat majority of commercial
robotic arm controllers in terms of ability to accept "normal" g-code
- AFAIK all the robots need special CAM postprocessors, which convert
Cartesian commands into motori position commands, so the code is not
understandable by the operator.
The problem with genserkins is customizing it, because it is very
complex uses very advanced math functions, like jacobian.
I think that I did everything needed for genserkins to work with
linear joints, but I need some help with testing it, because it does
not behave really the way I would expect it, but I am having
difficulties understanding, how to debug it.

Viesturs