Trajectory Generation of Straightened Knee Walking for Humanoid Robot iCub

Li Zhibin, Nikolas Tsagarakis, Darwin Caldwell, Bram Vanderborght

Research output: Chapter in Book/Report/Conference proceedingConference paperResearch

19 Citations (Scopus)


Most humanoid robots do not walk in a very human-like manner. In order
to decouple the planar and frontal motion, the z item in the ZMP equation is
set as zero, resulting is a constant height of the COM (Center of Mass). This constraint
creates the bent knee profile that is so typical of walking robots, which particularly
requires high motor torques. Hence, it is desirable to propose a trajectory
generator that produces a more straightened knee during walking which is more energy
efficient and natural when compared to the motion performed by humans. We
address this issue by adding a virtual spring-damper to the cart-table model. This
strategy combines the preview control, which generates desired horizontal COM
motion, and the virtual model, for generating vertical COM motion. The feasibility
is proved mathematically and demonstrated in MATLAB simulation of a multi-body
bipedal model. The walking pattern is applied to the child humanoid "iCub" using
the OpenHRP3 simulator. The simulated "iCub" successfully performs walking
gaits. The knee joint torque required by the proposed strategy is reduced, compared
to the one required by the cart-table scheme.
Original languageEnglish
Title of host publicationThe Eleventh International Conference on Control, Automation, Robotics and Vision (ICARCV 2010)
Number of pages8
Publication statusPublished - 10 Dec 2010
EventUnknown -
Duration: 10 Dec 2010 → …


Period10/12/10 → …


  • stretched knee walking
  • humanoid robot


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