R-Blink

Moulard et al., BioRob 2012 While robust trajectory following is a well-studied problem on mobile robots, the question of how to track accurately a trajectory on a humanoid robot remains open. This paper suggests a closed-loop trajectory tracking strategy aimed at humanoid robots. Compared to approaches from mobile robotics, this control scheme takes into account footsteps alteration, equilibrium constraints and singularities avoidance for humanoids. It provides a robust way to execute long and/or precise motion with the ability of correcting on-line preplanned trajectories in a very reactive manner. Results have been validated on the HRP-2 humanoid platform.

Baudouin et al., Humanoids 2011 In this paper, we illustrate experimentally an original real-time replanning scheme and architecture for humanoid robot reactive walking. Based on a dense set of actions, our approach uses a large panel of the humanoid robot capabilities and is particularly well suited for 3D collision avoidance. Indeed A-* approaches becomes difficult in such situation, thus the method demonstrated here relies on RRT. Combined with an approximation of the volume swept by the robot legs while walking, our method is able to cope with 3D obstacles while maintaining real-time computation. We experimentally validate our approach on the robot HRP-2.

Dang et al., Humanoids 2011 This paper focuses on realization of tasks with locomotion on humanoid robots. Locomotion and whole body movement are resolved as one unique problem. The same planner and controller are used for both stages of the movement. Final posture and footprint placements are found by resolving an optimization problem on the robot augmented by its footprints. Footstep replanning is done in realtime to correct perception and execution errors. The framework is demonstrated with the HRP-2 robot in a number of different scenarios.

Perrin et al., IROS 2011 In this paper we demonstrate an original equivalence between footstep planning problems, where discrete sequences of steps are searched for, and the more classical problem of motion planning for a 2D rigid shape, where a continuous collision-free path has to be found. This equivalence enables a lot of classical motion planning techniques (such as PRM, RRT, etc.) to be applied almost effortlessly to the specic problem of footstep planning for a humanoid robot.

Perrin et al., ICRA 2011We present a new biped walking pattern generator based on half-steps. Its key features are a) a 3-dimensional parametrization of the input space, and b) a simple homotopy that efficiently smooths the gait trajectory corresponding to a fixed sequence of steps. We show how these features can be ideally combined in the framework of sampling-based gait planning. We apply our approach to the robot HRP-2 and are able to quickly produce smooth and dynamically stable trajectories that are solutions to a difficult problem of gait planning.

Click here to watch the movie (45 Mo). In this movie, HRP-2 is operated through a SONY PS-3 wireless remote controller. The foot-steps are automically computed from the joystick input and checked using an approximation function. If the approximation function does not accept the foot-step the robot step on the spot. The modification of the CoM trajectory are computed in 300 micro-seconds at each new single support phase using Morisawa et al. method.

Click here to watch the movie (45 Mo). In this movie, HRP-2 is gently following a human through the information given by its force-sensor located in the wrist. The hands are controlled using a compliant controller with its apparent mass equivalent to the one of the robot. In the movie you can see different modes of walking: straight, rotation and lateral motions but there no special treatement between each of them. Self-collision is avoided thanks to an approximation function filtering the feasible and non-feasible foot-steps. You can also see the robot performing whole-body motion when it uses its chest-joint to follow the hand of the user and stay balanced.

Click here to watch the movie (47 Mo). In this video, technologies developped in the frame of R-Blink are used in a European Project called ROBOT@CWE. This project aims at performing collaborative tasks between a robot and a human. In this particular case, the robot is holding a panel with a human. It gently follows the human leading the way to the table where the panel should be stored.