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Head Devices - MTB - post information - Sim17

I have opened and posted and seen what this new OTB example from PC can do (and read the excellent doc.) It is impressive. I have been experimenting with head devices and have struggled a bit to know the best approach with the postprocessor. It seems that the machine model gives incomplete information to the postprocessor when a head device is attached to the kinematic chain (which it won't usually be in the model.) With (for instance) the universal head in this example - does the post use the "MOM_reload_iks_parameters" command to use some kinematic chain and get positions? There are a bunch of mom_isv... vars that may be the key but I am having trouble understanding them. It seems that the head device is more for CSE/ISV to have what it needs with little help to the postprocessor.
Windows 10 Pro

Re: Head Devices - MTB - post information - Sim17

Siemens Legend Siemens Legend
Siemens Legend

Hi Study,


in the OOTB libraries from Post Configurator is a standard implementation to support chains during postprocess. To get the correct positions it's necessary to define kinematic informations in the post about the chains, if they are different to the default configuration of postprocessor, e.g. spindle axis or axis vector of 4th/5th axis.

The post calculate the correct positions now, depending on the mom_kin-variables which belongs to the chain.

2018-01-08 10_13_01-Post Configurator - [sim17_turnmill_sinumerik.psc].jpg


There are 2 ways to create chains. Automatically from the MTB-Model, but then maybe Heads are not included if they are dynamic devices. It's also possible to add chains per Tcl commands and mapping chain conditions in the UI of Post Configurator. For further information how to handle the chains please take a look in the attached material.


When a chain is switching during postrun or is active in beginning of postprocess, the MOM_reload_kinematics command is used, so this reload e.g. the variables which are defined in the UI of Post Configurator and all the others from default chain. I know that we also use the MOM_reload_iks_parameters in some cases and this is implemeted in the generic command for calculation of 4th and 5th axis points.


In the sim17 sample the most of tcl-implementation belongs to logic of toolchange and which chain is active, dependent to the active device (proc LIB_SPF_define_active_chain_custom). For CSE we have defined some rules that simulation works fine, which are described in the document you mentioned.


Hope this helps and give a few more understanding of the Multichain feature.


Best regards


Re: Head Devices - MTB - post information - Sim17

Hi Thomas, I am not (yet) familiar with the PC methodology but from a UGPost standpoint - I got your point. We make TCL posts so far without PB or PC help and our goal is to have library head devices that when added to a machine - automatically adapt the post and ISV to be handled. We would like to handle when the file is postprocessed when head devices do and don't have the tools in them, and when they are and aren't attached to the machine. If I understand correctly - Sim17 post (even when everything attached) does not use the model kinematic chains (set mom_kin... and MOM_reload_kinematics instead of activate a certain model chain from machine or head MOM_reload_iks...) That was what I was asking.It seemed in my testing that the initial spindle direction (I thought controlled by "mom_kin_spindle_axis") didn't affect the result - I may have missed a step. The Head "object" in the tool view affects different variables and causes nx to issue an event. It seems with HT or HH these variables can be changed (early enough) to get good results. Thanks, Dan
Windows 10 Pro

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