Bilevel Optimization for Real-Time Control with Application to Locomotion Gait Generation

Fuente: arXiv
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Main Authors: Olkin, Zachary, Ames, Aaron D.
Format: Preprint
Published: 2024
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author Olkin, Zachary
Ames, Aaron D.
author_facet Olkin, Zachary
Ames, Aaron D.
contents Model Predictive Control (MPC) is a common tool for the control of nonlinear, real-world systems, such as legged robots. However, solving MPC quickly enough to enable its use in real-time is often challenging. One common solution is given by real-time iterations, which does not solve the MPC problem to convergence, but rather close enough to give an approximate solution. In this paper, we extend this idea to a bilevel control framework where a "high-level" optimization program modifies a controller parameter of a "low-level" MPC problem which generates the control inputs and desired state trajectory. We propose an algorithm to iterate on this bilevel program in real-time and provide conditions for its convergence and improvements in stability. We then demonstrate the efficacy of this algorithm by applying it to a quadrupedal robot where the high-level problem optimizes a contact schedule in real-time. We show through simulation that the algorithm can yield improvements in disturbance rejection and optimality, while creating qualitatively new gaits.
format Preprint
id arxiv_https___arxiv_org_abs_2409_12366
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Bilevel Optimization for Real-Time Control with Application to Locomotion Gait Generation
Olkin, Zachary
Ames, Aaron D.
Systems and Control
Robotics
Model Predictive Control (MPC) is a common tool for the control of nonlinear, real-world systems, such as legged robots. However, solving MPC quickly enough to enable its use in real-time is often challenging. One common solution is given by real-time iterations, which does not solve the MPC problem to convergence, but rather close enough to give an approximate solution. In this paper, we extend this idea to a bilevel control framework where a "high-level" optimization program modifies a controller parameter of a "low-level" MPC problem which generates the control inputs and desired state trajectory. We propose an algorithm to iterate on this bilevel program in real-time and provide conditions for its convergence and improvements in stability. We then demonstrate the efficacy of this algorithm by applying it to a quadrupedal robot where the high-level problem optimizes a contact schedule in real-time. We show through simulation that the algorithm can yield improvements in disturbance rejection and optimality, while creating qualitatively new gaits.
title Bilevel Optimization for Real-Time Control with Application to Locomotion Gait Generation
topic Systems and Control
Robotics
url https://arxiv.org/abs/2409.12366