Three-dimensional humanoid motion planning using COM feasible region and its application to ladder climbing tasks

Motion planning of humanoid's full-body trajectory requires satisfying various constraints such as balance, contact, joint limitation, kinematics, and collision. To obtain trajectory efficiently, related research has integrated coarse motion planning to fine full-body trajectory generation. In a three-dimensional motion, coarse motion planning considering at swing phase in addition to support phase is important because constraints at swing phase drastically change from support phase. In this paper, we propose a humanoid motion planner satisfying various constraints based on key pose generation by exploiting center-of-mass (COM) feasible region (CFR): (a) We show a method to project approximately balance constraints of statics and dynamics into CFR. (b) We propose a key pose generation capable of considering swing and support phase to satisfy asymptotically CFR constraint while satisfying kinematics constraints. (c) We show a method to interpolate obtained key pose and to obtain full-body trajectory. We validate our proposed method through experiments, in which the robot performs locomotion tasks especially related to ladder climbing under the stringent constraints.