Primal-Dual iLQR for GPU-Accelerated Learning and Control in Legged Robots

Fuente: arXiv
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Auteurs principaux: Amatucci, Lorenzo, Sousa-Pinto, João, Turrisi, Giulio, Orban, Dominique, Barasuol, Victor, Semini, Claudio
Format: Preprint
Publié: 2025
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author Amatucci, Lorenzo
Sousa-Pinto, João
Turrisi, Giulio
Orban, Dominique
Barasuol, Victor
Semini, Claudio
author_facet Amatucci, Lorenzo
Sousa-Pinto, João
Turrisi, Giulio
Orban, Dominique
Barasuol, Victor
Semini, Claudio
contents This paper introduces a novel Model Predictive Control (MPC) implementation for legged robot locomotion that leverages GPU parallelization. Our approach enables both temporal and state-space parallelization by incorporating a parallel associative scan to solve the primal-dual Karush-Kuhn-Tucker (KKT) system. In this way, the optimal control problem is solved in $\mathcal{O}(\log^2(n)\log{N} + \log^2(m))$ complexity, instead of $\mathcal{O}(N(n + m)^3)$, where $n$, $m$, and $N$ are the dimension of the system state, control vector, and the length of the prediction horizon. We demonstrate the advantages of this implementation over two state-of-the-art solvers (acados and crocoddyl), achieving up to a 60\% improvement in runtime for Whole Body Dynamics (WB)-MPC and a 700\% improvement for Single Rigid Body Dynamics (SRBD)-MPC when varying the prediction horizon length. The presented formulation scales efficiently with the problem state dimensions as well, enabling the definition of a centralized controller for up to 16 legged robots that can be computed in less than 25 ms. Furthermore, thanks to the JAX implementation, the solver supports large-scale parallelization across multiple environments, allowing the possibility of performing learning with the MPC in the loop directly in GPU. The code associated with this work can be found at https://github.com/iit-DLSLab/mpx.
format Preprint
id arxiv_https___arxiv_org_abs_2506_07823
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Primal-Dual iLQR for GPU-Accelerated Learning and Control in Legged Robots
Amatucci, Lorenzo
Sousa-Pinto, João
Turrisi, Giulio
Orban, Dominique
Barasuol, Victor
Semini, Claudio
Robotics
This paper introduces a novel Model Predictive Control (MPC) implementation for legged robot locomotion that leverages GPU parallelization. Our approach enables both temporal and state-space parallelization by incorporating a parallel associative scan to solve the primal-dual Karush-Kuhn-Tucker (KKT) system. In this way, the optimal control problem is solved in $\mathcal{O}(\log^2(n)\log{N} + \log^2(m))$ complexity, instead of $\mathcal{O}(N(n + m)^3)$, where $n$, $m$, and $N$ are the dimension of the system state, control vector, and the length of the prediction horizon. We demonstrate the advantages of this implementation over two state-of-the-art solvers (acados and crocoddyl), achieving up to a 60\% improvement in runtime for Whole Body Dynamics (WB)-MPC and a 700\% improvement for Single Rigid Body Dynamics (SRBD)-MPC when varying the prediction horizon length. The presented formulation scales efficiently with the problem state dimensions as well, enabling the definition of a centralized controller for up to 16 legged robots that can be computed in less than 25 ms. Furthermore, thanks to the JAX implementation, the solver supports large-scale parallelization across multiple environments, allowing the possibility of performing learning with the MPC in the loop directly in GPU. The code associated with this work can be found at https://github.com/iit-DLSLab/mpx.
title Primal-Dual iLQR for GPU-Accelerated Learning and Control in Legged Robots
topic Robotics
url https://arxiv.org/abs/2506.07823