Capturability-Based Pattern Generation for Walking With Variable Height

Caron, Stéphane; Escande, Adrien; Lanari, Leonardo; Mallein, Bastien

doi:10.1109/tro.2019.2923971

Cited by 57 publications

(63 citation statements)

References 46 publications

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“…[29][30][31] address the balance control of humanoid robot using VHIP model for planar motions. [32] further extends it to consider 3D movements, and develops an analytical tool to determine capturability in the VHIP model. [9] proposes an efficient analytical tool to compute zero-step capturability for multi-contact configuration using a centroidal dynamics model.…”

Section: Related Workmentioning

confidence: 99%

Robust Humanoid Contact Planning With Learned Zero- and One-Step Capturability Prediction

Lin

Righetti

Berenson

2020

IEEE Robot. Autom. Lett.

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Humanoid robots maintain balance and navigate by controlling the contact wrenches applied to the environment. While it is possible to plan dynamically-feasible motion that applies appropriate wrenches using existing methods, a humanoid may also be affected by external disturbances. Existing systems typically rely on controllers to reactively recover from disturbances. However, such controllers may fail when the robot cannot reach contacts capable of rejecting a given disturbance. In this paper, we propose a search-based footstep planner which aims to maximize the probability of the robot successfully reaching the goal without falling under disturbances. The planner considers not only the poses of the planned contact sequence, but also alternative contacts near the planned contact sequence that can be used to recover from external disturbances. Although this additional consideration significantly increases the computation load, we train neural networks to efficiently predict multi-contact zero-step and one-step capturability, which allows the planner to generate robust contact sequences efficiently. Our results show that our approach generates footstep sequences that are more robust to external disturbances than a conventional footstep planner in four challenging scenarios.

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Section: Related Workmentioning

confidence: 99%

Robust Humanoid Contact Planning With Learned Zero- and One-Step Capturability Prediction

Lin

Righetti

Berenson

2020

IEEE Robot. Autom. Lett.

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“…We consider varying the height of the VRP. In that case, it is proposed in [14], [15] to vary λ accordingly so that (6) and (7) always hold, but this results in a nonlinear problem. We propose instead to keep λ constant.…”

Section: Com and Cop Trajectories For Walking On A Piecewise Horimentioning

confidence: 99%

“…It is formulated as a linear problem which can be solved very efficiently with off-the-shelf solvers, by bounding nonlinearities conservatively (making sure to maintain kinematic and dynamic feasibility) in a very effective way: the CoM and Center of Pressure (CoP) trajectories obtained with this approach have been observed to be only a few millimeters away from the true optimum [13]. Comparable schemes typically consider predefined vertical motion [14] or predefined step placement [15] and don't provide complete kinematic and dynamic feasibility guarantees [7], which are all significant limitations.…”

Section: Introductionmentioning

confidence: 99%

Safe 3D Bipedal Walking through Linear MPC with 3D Capturability

Pajon

Wiebe

2019

2019 International Conference on Robotics and Automation (ICRA)

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We propose a linear MPC scheme for online computation of reactive walking motions, necessary for fast interactions such as physical collaboration with humans or collision avoidance in crowds. Unlike other existing schemes, it provides fully adaptable height, adaptable step placement and complete kinematic and dynamic feasibility guarantees, making it possible to walk perfectly safely on a piecewise horizontal ground such as stairs. A linear formulation is proposed, based on efficiently bounding the nonlinear term introduced by vertical motion, considering two linear constraints instead of one nonlinear constraint. Balance and Passive Safety guarantees are secured by enforcing a 3D capturability constraint. Based on a comparison between CoM and CoP trajectories involving exponentials instead of polynomials, this capturability constraint involves a CoM motion stopping along a segment of line, always maintaining complete kinematic and dynamic feasibility.

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“…Reduced models have been applied in balance and locomotion robotics [6,12,22] to derive critical properties such as capturability. Capturability is the ability of the model to keep balance from a given state and steer towards stable equilibrium configurations [4,7,16,26,30]. Capturability cannot be computed with full avatar body dynamics in the present state of art, as it would require nonlinear receding-horizon computations running in real time, but it is tractable within reduced models.…”

Section: Inverted Pendulum Modelmentioning

confidence: 99%

“…Lower-body motions of the avatar are reconstructed in accordance with the upper body. This reconstruction is based on a capturability-based locomotion control [4] that relies on the Inverted Pendulum Model (Section 2. The animation of the avatar is described in Section 3.…”

Section: Introduction Virtual Humans (Vh)mentioning

confidence: 99%

Lower body control of a semi-autonomous avatar in Virtual Reality: Balance and Locomotion of a 3D Bipedal Model

Thomasset¹,

Caron

Weistroffer

2019

25th ACM Symposium on Virtual Reality Software and Technology

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Animated virtual humans may rely on full-body tracking system to reproduce user motions. In this paper, we reduce tracking to the upper-body and reconstruct the lower body to follow autonomously its upper counterpart. Doing so reduces the number of sensors required, making the application of virtual humans simpler and cheaper. It also enable deployment in cluttered scenes where the lower body is often hidden. The contribution here is the inversion of the well-known capture problem for bipedal walking. It determines footsteps rather than center-of-mass motions and yet can be solved with an off-the-shelf capture problem solver. The quality of our method is assessed in real-time tracking experiments on a wide variety of movements.

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Capturability-Based Pattern Generation for Walking With Variable Height

Cited by 57 publications

References 46 publications

Robust Humanoid Contact Planning With Learned Zero- and One-Step Capturability Prediction

Robust Humanoid Contact Planning With Learned Zero- and One-Step Capturability Prediction

Safe 3D Bipedal Walking through Linear MPC with 3D Capturability

Lower body control of a semi-autonomous avatar in Virtual Reality: Balance and Locomotion of a 3D Bipedal Model

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