Reactive Leg Motion Generation Method under Consideration of Physical Constraints

This paper proposes a reactive leg motion generation method which integrates physical constraints into its generation process. In order to react given instructions instantaneously or to keep balance against external disturbances, feasible steps must be generated automatically in real-time for safety. In many cases this feasibility has been realized by using predefined steps or admissible stepping regions. However, these predefinitions are valid only in limited situations. The proposed method considers physical constraints during its generation process. It consists of a swing leg trajectory generator and a constraint solver. The former generates a swing leg trajectory considering rough self-collision avoidance between legs. The latter does joint velocities considering joint angle/velocity limits and precise self-collision avoidance. Moreover, in order to improve the possibility of feasible patterns being generated, a stiffness varying constraint and a landing position modification function are introduced. The proposed method is validated by experiments using a humanoid robot HRP-2.