Representation-Free Model Predictive Control for Dynamic Motions in Quadrupeds

Ding, Yanran; Pandala, Abhishek; Li, Chuanzheng; Shin, Young-Ha; Park, Hae Won

doi:10.1109/tro.2020.3046415

Cited by 121 publications

(73 citation statements)

References 63 publications

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“…The existing control approaches for quadrupedal locomotion rely on accurately estimated state input [1], [3], [4], [7], [10]- [13]. However, we observed that existing This work was supported by Samsung Research Funding & Incubation Center for Future Technology at Samsung Electronics under Project Number SRFC-IT2002-02.…”

Section: Introductionmentioning

confidence: 99%

Concurrent Training of a Control Policy and a State Estimator for Dynamic and Robust Legged Locomotion

Mun

Kim

et al. 2022

IEEE Robot. Autom. Lett.

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In this paper, we propose a locomotion training framework where a control policy and a state estimator are trained concurrently. The framework consists of a policy network which outputs the desired joint positions and a state estimation network which outputs estimates of the robot's states such as the base linear velocity, foot height, and contact probability. We exploit a fast simulation environment to train the networks and the trained networks are transferred to the real robot. The trained policy and state estimator are capable of traversing diverse terrains such as a hill, slippery plate, and bumpy road. We also demonstrate that the learned policy can run at up to 3.75 m/s on normal flat ground and 3.54 m/s on a slippery plate with the coefficient of friction of 0.22.

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Section: Introductionmentioning

confidence: 99%

Concurrent Training of a Control Policy and a State Estimator for Dynamic and Robust Legged Locomotion

Mun

Kim

et al. 2022

IEEE Robot. Autom. Lett.

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“…2) Gait Synthesis and Characterization: The 3D composition of planar orbits offers a way of synthesizing and characterizing 3D bipedal walking gaits. The gait synthesis and characterization via composition of planar orbits can potentially be extended to other multi-legged systems, e.g., the bounding behavior on quadrupedal locomotion [59] can be viewed as producing a P2 orbit in its sagittal plane. The extension appears to be non-trivial but possible.…”

Section: A Implicationsmentioning

confidence: 99%

3-D Underactuated Bipedal Walking via H-LIP Based Gait Synthesis and Stepping Stabilization

Xiong

Ames

2022

IEEE Trans. Robot.

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In this paper, we present a Hybrid-Linear Inverted Pendulum (H-LIP) based approach for synthesizing and stabilizing 3D underactuated bipedal walking. The H-LIP model is proposed to capture the essential components of the underactuated part and actuated part of the robotic walking. The walking gait of the robot is then synthesized based on the H-LIP. We comprehensively characterize the periodic orbits of the H-LIP and provably derive their stepping stabilization. The step-to-step (S2S) dynamics of the H-LIP is then utilized to approximate the S2S dynamics of the horizontal state of the center of mass (COM) of the robotic walking, which results in a H-LIP based stepping controller to provide desired step sizes to stabilize the robotic walking. By realizing the desired step sizes, the robot achieves dynamic and stable walking. The approach is evaluated in both simulation and experiment on the 3D underactuated bipedal robot Cassie, which demonstrate dynamic walking behaviors with both versatility and robustness.

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“…Building upon similar ideas, regularized predictive control frameworks that addresses nonlinearities in the original problem via convexifying the cost function have been designed and verified with hardware implementations [26][27][28]. Leveraging a variational-based linearization technique, optimization-based strategies have demonstrated their ability to manage underactuated balance [29] and dynamic locomotion [30]. Winkler et al [31] worked directly with the nonlinear problem and applied standard solvers to tackle the problem.…”

Section: Related Workmentioning

confidence: 99%

Quadruped Capturability and Push Recovery via a Switched-Systems Characterization of Dynamic Balance

Chen¹,

Hong²,

Yang³

et al. 2022

Preprint

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This paper studies capturability and push recovery for quadrupedal locomotion. Despite the rich literature on capturability analysis and push recovery control for legged robots, existing tools are developed mainly for bipeds or humanoids. Distinct quadrupedal features such as point contacts and multiple swinging legs prevent direct application of these methods. To address this gap, we propose a switched systems model for quadruped dynamics, and instantiate the abstract viability concept for quadrupedal locomotion with a time-based gait. Capturability is characterized through a novel specification of dynamically balanced states that addresses the time-varying nature of quadrupedal locomotion and balance. A linear inverted pendulum (LIP) model is adopted to demonstrate the theory and show how the newly developed quadrupedal capturability can be used in motion planning for quadrupedal push recovery. We formulate and solve an explicit model predictive control (EMPC) problem whose optimal solution fully characterizes quadrupedal capturability with the LIP. Given this analysis, an optimization-based planning scheme is devised for determining footsteps and center of mass references during push recovery. To validate the effectiveness of the overall framework, we conduct numerous simulation and hardware experiments. Simulation results illustrate the necessity of considering dynamic balance for quadrupedal capturability, and the significant improvement in disturbance rejection with the proposed strategy. Experimental validations on a replica of the Mini Cheetah quadruped demonstrate an up to 100% improvement as compared with state-of-the-art.

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Representation-Free Model Predictive Control for Dynamic Motions in Quadrupeds

Cited by 121 publications

References 63 publications

Concurrent Training of a Control Policy and a State Estimator for Dynamic and Robust Legged Locomotion

Concurrent Training of a Control Policy and a State Estimator for Dynamic and Robust Legged Locomotion

3-D Underactuated Bipedal Walking via H-LIP Based Gait Synthesis and Stepping Stabilization

Quadruped Capturability and Push Recovery via a Switched-Systems Characterization of Dynamic Balance

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