Add optional format alternative to motor reflected inertia #44
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- Add 'motorReflectedInertiaFormat' popup parameter to the simulator mask.
'vector': the input 'motorInertias' is the vector of diagonal terms of Im*inv(G)
'matrix': the input 'motorInertias' is the matrix inv(TG)'*Im*inv(TG). The inertia
can be coupled.
- Propagated 'motorReflectedInertiaFormat' to the underlying MATLAB System.
- The addition of the motor inertia to the mass matrix depends on this flag.
'matrix'=> M = M + blkdiag(zeros(6),motorInertias), accounting for all the
coupling terms in 'motorInertias'.
- That processing had to be done in 'step_block', as the code generation considers
at compilation time also the branching paths not accessible at runtime, causing a
size mismatch in the computation of M if the branching consition is not a constant,
or if it is "Tunable".
…lization - fixed the mask initialization: the param needs to be retrieved through get_param, otherwise it gets the wrong value. - the initialization of 'motorReflectedInertiaFormat' to 'vector' in the 'step_block' class was corrupting its value and causing the switch case to fall on the 'otherwise' case when processing the mass matrix. As a result, even with wrong motor inertia dimensions, the model would run successfully but without ever applying the motor inertias. - Checked that the combinations [input inertia vector/param 'matrix'] and [input inertia matrix/ param 'vector'] fail at runtime as expected.
Side note on model
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@traversaro , this is ready for review. I will be checking the installation of the library and integration with the controller (robotology/whole-body-controllers#122). |
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Update with respect to the last PR #44 .
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Update with respect to the last PR #44 .
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Motivation and main changes
The integration of the$\Gamma^{-\top} G^{-1} I _m G^{-1} \Gamma^{-1}$ , since this expression resulted in a diagonal matrix in the case of a robot without coupled joints. In the case of iCub, the shoulder joints are coupled, as well as the torso joints. The matrix $\Gamma^{-\top} G^{-1} I _m G^{-1} \Gamma^{-1}$ is not diagonal anymore (robotology/whole-body-controllers#121 (comment)), and so the coupling terms need to be accounted for. For this reason we pass the full matrix mentioned above to the simulation block
matlab-whole-body-simulatorwith the YOGA controller fromwhole-body-controllersrepository (robotology/whole-body-controllers#122) required a change in the format of the reflected motor inertia parameters. These used to be defined as a column vector composed of the diagonal terms ofRobotDynWithContacts.There are two impacts on the block
RobotDynWithContacts:step_block.motorReflectedInertiaFormat = 'vector'step_block.motorReflectedInertiaFormat = 'matrix'step_block.motorReflectedInertiaFormat'vector':Mout = M + diag([zeros(6,1);motorInertias]);'matrix':Mout = M + blkdiag(zeros(6),motorInertias);Design Details
RobotDynWithContactsinterface=> A parameter #4 was added in the "parameters & Dialog" pane of the mask editing.
=> The mask initialization was updated for setting
propMotorReflectedInertiaFormatinput to MATLAB System lying under the mask.=> input parameter
propMotorReflectedInertiaFormatwas added to the MATLAB System.Working combinations are as shown below:
All other combinations fail.
step_block.motorReflectedInertiaFormatstep_block.motorReflectedInertiaFormat.at compilation time also the branching paths not accessible at runtime, causing a
size mismatch in the computation of M if the branching consition is not a constant,
or if it is "Tunable".
PR verification
Check the working and failing combinations described above, for instance on model
iCubGenova04.When setting a "failing" combination, the model compiles but fails early at runtime:
or...