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Is there a way to get the Centroidal Momentum Matrix in Robotics Toolbox?

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In Robotics toolbox centerOfMass function returns center of mass of the robot and center of mass Jacobian of it. When I look inside the function I have realized that centroidal momentum matrix (written as cmm) is also being calculated but not returned, and I want to get that matrix. I cannot overwrite the file to change the outputs, and cannot write a wrapper due to class property being private. The error:
'No public property 'TreeInternal' for class 'RigidBodyTree'
Is there a way to get the Centroidal Momentum Matrix in Robotics Toolbox somehow? Thanks

Accepted Answer

Amal George M
Amal George M on 11 Sep 2018
Hi Yigit,
In order to access this variable, you can edit the 'RigidBodyTree.m' file outside of MATLAB. At the location "<Matlabroot>\toolbox\robotics\robotmanip\+robotics" (Write permission required). You can add 'cmm' in the list of output variables to the function 'centerOfMass()'. The modified line will be:
function [com, comJac, cmm] = centerOfMass(obj, varargin)
Restart MATLAB for changes to take effect.
Full disclosure: If there is a dependency associated with this function it might result in an error in future. Also, there is no guarantee that the file will be accessible in later releases.
  1 Comment
Marijn Peters
Marijn Peters on 7 May 2020
Hi Amal,
Do you happen to know if this is still possible in matlab 2020a? Or maybe another way to find the CMM in simscape?
kind regards,
Marijn

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