Coordinate partitioning

Partitionning of the generalized coordinates into independent and dependent variables (for constrained multibody systems only).
For more information, see Robotran theoritical framework.

Note: This module must be run once prior to any other module in case of multibody model containing loop and/or user-constraint.

Code sample

For running the coordinate partitioning, insert the following code in your main script and adapt it to your need :

%% 2. Coordinate partitioning [mbs_exe_part]                                % For constrained MBS only
%--------------------------------------------------------------------------
MBS_user.process = 'part';
 
[id_joint1, id_joint4, id_joint6] = mbs_get_joint_id(mbs_info,'joint1','joint4','joint6');      % Get joint indices from joint names
qu_id = [id_joint1, id_joint4, id_joint6];
mbs_data = mbs_set_qu(mbs_data,qu_id);                                                          % Set variables [qu_id] as independent 
 
[id_joint3, id_joint5] = mbs_get_joint_id(mbs_info,'joint3','joint5');                          % Get joint indices from joint names
qv_id = [id_joint3, id_joint5];
mbs_data = mbs_set_qv(mbs_data,qv_id);                                                          % Set variables [qv_id] as dependent
 
qc_id = mbs_get_joint_id(mbs_info,{'joint2'});                                                  % Get joint indices from joint names
mbs_data = mbs_set_qc(mbs_data,qc_id);                                                          % Set variables [qc_id] as driven
 
opt.part = {'rowperm','yes','threshold',1e-9,'verbose','yes'};
% other options : 'visualize', 'clearmbsglobal'                             % Help about options on www.robotran.be
 
[mbs_part,mbs_data] = mbs_exe_part(mbs_data,opt.part);                      % Coordinate partitioning process
 
% Coordinate partitioning results
disp('Coordinate partitioning results');
disp(['Sorted independent variables = ', mat2str(mbs_part.ind_u)]);
disp(['Permutated dependent variables = ', mat2str(mbs_part.ind_v)]);
disp(['Permutated independent constraints = ', mat2str(mbs_part.hu)]);
disp(['Redundant constraints = ', mat2str(mbs_part.hv)]);

Use

The partitioning is performed by the function mbs_exe_part().

The user specifies the desired options of the partitioning in MBS_part_opt structure. The results are provided in the MBS_part structure.

The function calls successively :

See diagram below for more details :

partioning function diagram