Question on calculate A Matrix

ShuoYangRobotics / A1-QP-MPC-Controller

An open source implementation of MIT Cheetah 3 controllers

GNU Affero General Public License v3.0

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Question on calculate A Matrix #34

Open lgkimjy opened 3 months ago

lgkimjy commented 3 months ago

Dear @ShuoYangRobotics ,

In ConvexMPC.cpp, I do not understand why did you set value 1 at line 129, according to the ConvexMPC on MIT Cheetah3 paper, isn't it should be zero?

https://github.com/ShuoYangRobotics/A1-QP-MPC-Controller/blob/79c91302b5855cf245a852aefa7162449bf4ac9e/src/a1_cpp/src/ConvexMpc.cpp#L110-L130

can you explain why you put 1 in line 129?

jbwenjoy commented 3 months ago

I think this is because of the gravity term. The cheetah paper described this at the end of section III that they added an additional gravity state to put the dynamics into state-space form. Here the MPC_STATE_DIM is also 13 instead of 12.

Please correct me if I'm wrong.