caa a22 4500 528782088 20190822030952.0 cr unu---uuuuu 180924e20180704xx s 000 0 eng 10.3929/ethz-b-000276805 doi 10.1109/LRA.2018.2852785 doi (ETHRESEARCH)oai:www.research-collection.ethz.ch:20.500.11850/276805 Trajectory Optimization with Implicit Hard Contacts [Elektronische Daten] [Jan Carius, id_orcid 0000-0001-7158-9404, René Ranftl, Vladen Koltun, Marco; id_orcid 0000-0002-4285-4990 Hutter] Open access ethresearch We present a contact invariant trajectory optimization formulation to synthesize motions for legged robotic systems. The method is capable of finding optimal trajectories subject to whole body dynamics with hard contacts. Contact switches are determined automatically. We make use of concepts from bilevel optimization to find gradients of the system dynamics including the constraint forces and subsequently solve the optimal control problem with the unconstrained iLQR algorithm. Our formulation achieves fast computation times and scales well with the number of contact points. The physical correctness of the produced trajectories is verified through experiments in simulation and on real hardware. We showcase our method on a single legged hopper for which jumping and forward hopping motions are synthesized with an arbitrary number of contact switches. The jumping trajectories can be tracked on the robot and allow it to safely liftoff and land. In Copyright - Non-Commercial Use Permitted http://rightsstatements.org/page/InC-NC/1.0 ethresearch Dynamics ethresearch Optimization and Optimal Control ethresearch Legged robots ethresearch Carius Jan joint author id_orcid 0000-0001-7158-9404 joint author Ranftl René joint author Koltun Vladen joint author Hutter Marco; id_orcid 0000-0002-4285-4990 joint author IEEE Robotics and Automation Letters Piscataway, NJ : IEEE 3 (4), pp. 3316-3323 2377-3766 http://hdl.handle.net/20.500.11850/276805 text/html WWW-Backlink auf das Repository (Open access) 1 Journal Article ethresearch ETHRESEARCH 856 40 http://hdl.handle.net/20.500.11850/276805 text/html WWW-Backlink auf das Repository (Open access) ETHRESEARCH 700 1- Carius Jan joint author ETHRESEARCH 700 -- id_orcid 0000-0001-7158-9404 joint author ETHRESEARCH 700 1- Ranftl René joint author ETHRESEARCH 700 1- Koltun Vladen joint author ETHRESEARCH 700 1- Hutter Marco; id_orcid 0000-0002-4285-4990 joint author ETHRESEARCH 773 0- IEEE Robotics and Automation Letters Piscataway, NJ : IEEE 3 (4), pp. 3316-3323 2377-3766 BK010053 XK010053 XK010000 ETHRESEARCH ETHRESEARCH ETHRESEARCH Journal Article Open access