RoboBoom
KAIST DRCD Lab· December 14, 2023· 8:02

Seamless Reaction Strategy for Bipedal Locomotion Exploiting Real-Time Nonlinear MPC

KAIST DRCD Lab researchers present a real-time nonlinear model predictive control method for helping bipedal robots recover from disturbances using ankle, hip, and stepping adjustments.

In this talk

  1. 0:11

    Combining walking responses

    The method combines three ways to respond to pushes: ankle torque, hip motion that counters body rotation, and changes to the swing foot’s landing position or timing. The researchers formulate these responses together in a nonlinear model predictive control problem for bipedal walking.

  2. 1:35

    Simulated push recovery

    Simulations cover forward and sideways pushes during forward and sideways walking, including disturbances up to 23.5 newton-seconds. When footstep timing changes are disabled, the model withstands only 20.5 newton-seconds, a 13.6% reduction in recovery capacity.

  3. 3:10

    Adapting to different robots and control weights

    The method is also evaluated on point-foot and small-foot models that cannot use ankle responses. Changing the control weighting factors shifts the response among ankle action, hip motion, landing-position changes, and footstep-timing changes.

  4. 5:52

    Real-robot tests

    The controller runs on Gazelle, a 13-degree-of-freedom biped, with pushes measured by a force sensor. Tests report recovery from disturbances up to 46% above a baseline and a side push of 12.99 newton-seconds, 57.4% above baseline; solve times meet real-time requirements.

  5. 7:16

    Walking over debris

    In the final experiment, Gazelle walks with 0.15-meter strides over debris containing obstacles of different heights and objects that may move.

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