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

2014-10-08 11:16 GMT+02:00 Ruben Smits <[email protected]>:

>
>
> On Wed, Oct 8, 2014 at 10:57 AM, Vincent Padois <[email protected]>
> wrote:
>
>> 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 ?
>>
>>
>
> Not that I remember, it was actually not me creating that model but Wilm
> Decre
>
>
>>
>>>
>>>> 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.
>>
>
> Yes, but think we used a similar/same approach to determine it, you should
> ask Wilm for more information.
>

Thanks. I will ask him.

Best
Vincent


>
> R.
>
>
>>
>> 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
>>>
>>>
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>>
>>
>
>
> --
> Ruben Smits, CTO
> +32 479 511 786
> Intermodalics - Kapeldreef 60, 3001 Heverlee - BELGIUM
> www.intermodalics.eu
>
>
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> This email and any attached files are confidential and may be legally
> privileged. Any copy, print or forward of this email, without the agreement
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