Re: sign of the moment of inertia in the description of the KUKA LWR dynamics in KDL

Hello Ruben

2014-10-08 10:13 GMT+02:00 Ruben Smits <[email protected]>:

>
>
> On Fri, Sep 19, 2014 at 2:02 PM, Vincent Padois <[email protected]>
> wrote:
>
>> Hello,
>>
>> I am using the KUKA LWR kinematics and dynamics description that can be
>> found in the KDL source code here:
>> orocos_kinematics_dynamics/orocos_kdl/models/kukaLWR_DHnew.cpp
>>
>> and I am surprised to see that some of the  moments of inertia of the
>> segments (joint 2 and 4 associated segments) are negative. By definition
>> these terms should be positive. Can someone tell me more about the reason
>> for these negative signs ?
>>
>
> It has been a long time, so I don't remember exactly but it might be due
> to the fact that those axes are not right-hand turning?
>

Then, if this information is only embedded in the moment of inertia I don't
understand why the Jacobian would be correct (it is correct when compared
to the one provided by KUKA). So there must be some other reason. Have you
actually used the LWR  dynamics model from KDL to perform dynamic
decoupling control on the real robot ?


>
>
>> Also, how were these (I mean all of them, not just the negative ones)
>> values identified/obtained ?
>>
>
> AFAIK they were obtained using
> http://limo.libis.be/Lirias:lirias123456789/167731 on a LWR4 (not a LWR4+
> IIRC)
>

I looked inside and the only data available are the one from a KUKA IR 361.

Best
V


>
> R,
>
>
>>
>> Thanks in advance for your help,
>> Best
>> Vincent
>>
>> --
>> Vincent Padois
>> http://pages.isir.upmc.fr/~padois/website
>>
>> --
>> Orocos-Dev mailing list
>> [email protected]
>> http://lists.mech.kuleuven.be/mailman/listinfo/orocos-dev
>>
>>
>
>
> --
> Ruben Smits, CTO
> +32 479 511 786
> Intermodalics - Kapeldreef 60, 3001 Heverlee - BELGIUM
> www.intermodalics.eu
>
>
> ---------------------------------------------------------------------------------------------------------------------------------------
> This email and any attached files are confidential and may be legally
> privileged. Any copy, print or forward of this email, without the agreement
> of sender or addressee, is strictly prohibited. Misuse is a violation of
> the law on personal data protection (D. Lgs. 196/2003) and on secrecy of
> correspondence (art. 616 cp). If you have received this transmission in
> error please notify the sender immediately and then delete this email and
> any attached files.
>

-- 
Orocos-Dev mailing list
[email protected]
http://lists.mech.kuleuven.be/mailman/listinfo/orocos-dev