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Switch between Profile Position mode and Profile Velocity mode.

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Hi~

I'm using an AKD-P01206-NBCC drive via CANopen.

My device need to work in pp mode and pv mode,

but when I switch between the two mode , something wired happen.

for example , when I set the target position to 90 degree (control bit 6 = 0, target position is absolute)

the axis move to 90 degree,

and I switch to pv mode ,set the target velocity to 360 degree/s , the axis starts to spin,

then I set the target velocity to 0 ,

the axis stopped and the position actual value let's say 12345 degree.

after that I switch back to profile position mode , set the target position to 12000 degree,still absolute position .

something wired happened...

the axis first moves to 90 degree , the position I quit profile position mode,

and then it goes to 12000 degree... what I want is the motion starts from the actual position(12345 degree) and goes to 12000 degree.

 

another thing I can't understand is that when I set the target position ,

in Kollmorgen WorkBench I check the MT.P value , Refresh, but it doesn't change , 

however the pp motion works all fine ...

 

How can I switch between the two mode properly?

Thanks for your help.

Best regards.

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Hi MayBe_89,

As I'm not a Kollmorgen intern not sure what exactly is going on when switching modes. Maybe positioning is not update or what so ever in velocity mode.

One suggestion to not switch mode at all. Its possible to get something like a velocity mode also in profile position mode. This can be achieved with endless relative moves call, which are blended in velocity or acceleration. There is a catch for stopping! You need to do some calculation on which relative distance and ramping it is possible for the actual velocity to have a close to optimum stopping behavior.

So do some tests if this works out for you and if the stopping switching behavior are acceptable.

 

If it helps I got a public git showing a lot of code on how to control a AKD in profile position with a EtherCat Master https://bitbucket.org/MrPreetz/akd_profile_position/src/master/ feel free to use and suggest improvements. As always with code snippets some disclaimer, WITHOUT WARRANTY OF ANY KIND.

Hope this could help some even if its open for quite some time now.

Regards Martin

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Thanks a lot Martin!
I tried to find out why it works like that these days,it seems that when I change the UNIT from workbench defined unit to DS402 defined unit (set DS402.POSFCFEED,set DS402.POSFCHAFTREV...),this phenomenon will happen,but I'm not sure if there is some other parameters I set incorrectly,
Like you say , I'd better not switch mode at all...maybe a long long distance relative motion cammand will make it work like pv mode,or I have to use ip mode to write the pv and pp motion .
Again, thanks for the advice ! And I'll follow the git :)

MayBe_89 - Thu, 08/12/2021 - 01:28

What about the objects your using, guess its h6081 for velocity in PP- and PV-Mode?
Have your tried using h60FF in PV-Mode. (Makes the mapping a little bit longer as it introduces an object only used in PV.)

But as you mention the scaling there is something ringing in my head about this. Not having a test system handy currently this is only guessing.

MartinRupf - Thu, 08/12/2021 - 01:35

Yes I'm using h6081 for velocity in PP and h60ff in PV mode,all via SDO,
will it be compatiblity issues for Kollmorgen , I don't know ,it seems PP mode have some connections with the motion task in workbench.

MayBe_89 - Thu, 08/12/2021 - 02:35
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