Real-time planning and execution of evasive motions for a humanoid robot

Abstract

We present a method for performing evasive motions with a humanoid robot. In the considered scenario, the robot is standing in a workspace, when a moving obstacle (e.g., a human, or another robot) enters its safety area and heads towards it; the humanoid must plan and execute in real-time a maneuver that avoids the collision. The proposed method goes through several conceptual steps. Once the entrance of the moving obstacle in the safety area is detected, its approach direction relative to the robot is determined. On the basis of this information, a suitable evasion maneuver represented by footsteps is generated. From these, an appropriate trajectory is computed for the Center of Mass of the humanoid. Finally, joint motion commands are generated so as to track such trajectory. All computations make use of closed-form expressions and are therefore suitable for real-time implementation. The proposed approach is validated via simulations and experiments on a NAO humanoid. The possibility of adapting the basic method so as to be used in a replanning framework is also investigated.

Intrinsically stable MPC for humanoid gait generation

“…• using a more complete approximate model which accounts for the swinging foot dynamics and removes the constant CoM height assumption. • applying the proposed MPC approach to the generation of evasive motions [18].…”

Real-time pursuit-evasion with humanoid robots

“…In [12] we have discussed two possibilities, i.e., move back and move aside. In this paper we will consider only the second, which is more effective in confined spaces.…”

“…It receives in input the footstep sequence, from which a reference trajectory for the ZMP is generated by polynomial interpolation. Computation of a stable CoM trajectory associated to the ZMP reference is performed using the same LIP-based method described in [12]; see also [18] for further details.…”

“…In a previous work [12], we have addressed a basic safety problem for humanoids: in particular, a situation was considered where the robot is threatened by a moving obstacle (e.g., a human, or another robot) that enters its safety area headed for collision. Under the assumption that the moving obstacle did not change its direction, we developed and implemented a method by which the humanoid could plan and execute in real time an evasion maneuver.…”

A Control Architecture with Online Predictive Planning for Position and Torque Controlled Walking of Humanoid Robots

“…All these considerations suggest to use a simple kinematic model to generate the walking trajectories: the unicycle model (see, e.g., [9]). This model can be used to plan footsteps in a corridor with turns and junctions using cameras [10], or to perform evasive robot motions [11]. In all these cases, however, the robot velocity is kept to a constant value.…”