Kyoungchul Kong Hyosang Moon Beomsoo Hwang Doyoung Jeon Masayoshi Tomizuka Impedance Compensation of SUBAR for Back-Drivable Force-Mode Actuation. 512-521 2009 25 IEEE Transactions on Robotics 3 http://dx.doi.org/10.1109/TRO.2009.2019786 db/journals/trob/trob25.html#KongMHJT09