One of the main challenges of planning legged locomotion in complex environments is the combinatorial contact selection problem. Recent contributions propose to use integer variables to represent which contact surface is selected, and then to rely on modern mixed-integer (MI) optimization solvers to handle this combinatorial issue. To reduce the computational cost of MI, we exploit the sparsity properties of L1 norm minimization techniques to relax the contact planning problem into a feasibility linear program. Our approach accounts for kinematic reachability of the center of mass (COM) and of the contact effectors. We ensure the existence of a quasi-static COM trajectory by restricting our plan to quasi-flat contacts. For planning 10 steps with less than 10 potential contact surfaces for each phase, our approach is 50 to 100 times faster that its MI counterpart, which suggests potential applications for online contact re-planning. The method is demonstrated in simulation with the humanoid robots HRP-2 and Talos over various scenarios.


ICRA 2019, version with distortion-free conformal mapping:

  title={Distortion-free Robotic Surface-drawing using Conformal Mapping},
  author={Song, Daeun and Kim, Young J},
  booktitle={2019 International Conference on Robotics and Automation (ICRA)},

ICRA 2018, “Artistic Pen Drawing on an Arbitrary Surface using an Impedance-controlled Robot”, primary version without a camera:

  title={Artistic pen drawing on an arbitrary surface using an impedance-controlled robot},
  author={Song, Daeun and Lee, Taekhee and Kim, Young J},
  booktitle={2018 IEEE International Conference on Robotics and Automation (ICRA)},