Updated the convention of writing and added some comments to describe the codes.
Updated the contact forces calculation.
Writing the contact forces into a file.
Trying to simplify the contact forces equations.
Built a module to simplify the equations of contact forces, and this simplification is unique for this derivation of the model.
Simplify the equations of contact forces derived from manual derivation.
Updated the simplification with several rounds.
Comments on the simplification of equations of contact forces since they look infeasible, needing more professional codes instead of manual simplification.
Imported function of front_contact() from Jason's DynamicistToolKit.
Commented on the wirting of equations of contact forces after writing the equations into the function of contactforce_constraints in dtk.