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robotology-legacy / mex-wholebodymodel

Matlab MEX interface to the iWholeBodyModel interface.
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Mex-wholebodymodel functions not explicit with respect of the floating base #26

Closed gabrielenava closed 8 years ago

gabrielenava commented 8 years ago

I need to compute numerically the partial derivatives both the mass matrix and the jacobian with respect of a given steady state position. Seems that using wbm functions is possible to compute a variation in mass matrix and jacobian with respect of each joints variable but not with respect of the position and rotation of the floating base.

naveenoid commented 8 years ago

it looks like ideally you would prefer an implementation of mass-matrix which takes as an input the complete state (floating base + joint position). Do you think if I implement something like 'massMatrixFullState' it would be useful for you?

Naveen Kuppuswamy, PhD Post-doctoral Fellow, Cognitive Humanoids Lab, Department of Robotics, Brain and Cognitive Sciences (RBCS), Istituto Italiano di Tecnologia, Genova, Italy

On Thu, Sep 17, 2015 at 10:36 AM, gabrielenava notifications@github.com wrote:

I need to compute numerically the partial derivatives both the mass matrix and the jacobian with respect of a given steady state position. Seems that using wbm functions is possible to compute a variation in mass matrix and jacobian with respect of each joints variable but not with respect of the position and rotation of the floating base.

— Reply to this email directly or view it on GitHub https://github.com/robotology-playground/mex-wholebodymodel/issues/26.

DanielePucci commented 8 years ago

@gabrielenava

gabrielenava commented 8 years ago

yes, i think it will be useful, and i need something similar for the wbm_jacobian.

I have one more question: if i set the robot in a given initial position, can i compute the mass

matrix with respect of the given position and then just change by a delta one of the input in wbm_massmatrix to correctly obtain the new values?

i mean, without changing the entire initial position, make the wbm_updatestate, obtain the new mass matrix, reset the original position, do again update state (which is what i'm doing now). this will save a lot of passages, if it is correct. thanks

Gabriele

Da: Naveen Kuppuswamy notifications@github.com Inviato: giovedì 17 settembre 2015 09.08 A: robotology-playground/mex-wholebodymodel Cc: Gabriele Nava Oggetto: Re: [mex-wholebodymodel] Mex-wholebodymodel functions not explicit with respect of the floating base (#26)

it looks like ideally you would prefer an implementation of mass-matrix which takes as an input the complete state (floating base + joint position). Do you think if I implement something like 'massMatrixFullState' it would be useful for you?

Naveen Kuppuswamy, PhD Post-doctoral Fellow, Cognitive Humanoids Lab, Department of Robotics, Brain and Cognitive Sciences (RBCS), Istituto Italiano di Tecnologia, Genova, Italy

On Thu, Sep 17, 2015 at 10:36 AM, gabrielenava notifications@github.com wrote:

I need to compute numerically the partial derivatives both the mass matrix and the jacobian with respect of a given steady state position. Seems that using wbm functions is possible to compute a variation in mass matrix and jacobian with respect of each joints variable but not with respect of the position and rotation of the floating base.

Reply to this email directly or view it on GitHub https://github.com/robotology-playground/mex-wholebodymodel/issues/26.

Reply to this email directly or view it on GitHubhttps://github.com/robotology-playground/mex-wholebodymodel/issues/26#issuecomment-141018230.

naveenoid commented 8 years ago

I will close this issue as I will address it directly in https://github.com/robotology-playground/mex-wholebodymodel/issues/27