Planning and Execution of Dynamic Whole-Body Locomotion for a Hydraulic Quadruped on Challenging Terrain

Alexander W Winkler (1, 2) , Carlos Mastalli (1) , Ioannis Havoutis (1) , Michele Focchi (1) , Darwin G. Caldwell (1) , Claudio Semini (1)

1 IIT - Department of Advanced Robotics
2 IRIS - Institute of Robotics and Intelligent Systems

We present a framework for dynamic quadrupedal locomotion over challenging terrain, where the choice of appropriate footholds is crucial for the success of the behaviour. We build a model of the environment on-line and on-board using an efficient occupancy grid representation. We use Anytime Repairing A* (ARA*) to search over a tree of possible actions, choose a rough body path and select the locally-best footholds accordingly. We run a n-step lookahead optimization of the body trajectory using a dynamic stability metric, the Zero Moment Point (ZMP), that generates natural dynamic whole-body motions. A combination of floating-base inverse dynamics and virtual model control accurately executes the desired motions on an actively compliant system. Experimental trials show that this framework allows us to traverse terrains at nearly 6 times the speed of our previous work, evaluated over the same set of trials.

Domaines: Robotique [cs.RO]; Optimisation et contrôle [math.OC]

Alexander W Winkler, Carlos Mastalli, Ioannis Havoutis, Michele Focchi, Darwin G. Caldwell, et al.. Planning and Execution of Dynamic Whole-Body Locomotion for a Hydraulic Quadruped on Challenging Terrain. IEEE International Conference on Robotics and Automation (ICRA), May 2015, Seattle, United States. ⟨hal-01661774⟩