@article{gregg_controlled_2013, title = {Controlled {Reduction} with {Unactuated} {Cyclic} {Variables}: {Application} to 3D {Bipedal} {Walking} with {Passive} {Yaw} {Rotation}}, author = {Gregg, R.D. and Righetti, L.}, journal = {IEEE Transactions on Automatic Control}, volume = {58}, number = {10}, pages = {2679--2685}, month = oct, year = {2013}, doi = {10.1109/TAC.2013.2256011}, url = {https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4279450/}, month_numeric = {10} }