Search Results for author: Antonis Papachristodoulou

Found 15 papers, 8 papers with code

NLBAC: A Neural Ordinary Differential Equations-based Framework for Stable and Safe Reinforcement Learning

2 code implementations23 Jan 2024 Liqun Zhao, Keyan Miao, Konstantinos Gatsis, Antonis Papachristodoulou

Reinforcement learning (RL) excels in applications such as video games and robotics, but ensuring safety and stability remains challenging when using RL to control real-world systems where using model-free algorithms suffering from low sample efficiency might be prohibitive.

Reinforcement Learning (RL) Safe Reinforcement Learning

A contract negotiation scheme for safety verification of interconnected systems

no code implementations6 Nov 2023 Xiao Tan, Antonis Papachristodoulou, Dimos V. Dimarogonas

This paper proposes a (control) barrier function synthesis and safety verification scheme for interconnected nonlinear systems based on assume-guarantee contracts (AGC) and sum-of-squares (SOS) techniques.

Rational Neural Network Controllers

no code implementations12 Jul 2023 Matthew Newton, Antonis Papachristodoulou

However, one prominent issue with these methods is that they use existing neural network architectures tailored for traditional machine learning tasks.

Safety-Aware Optimal Control for Motion Planning with Low Computing Complexity

no code implementations28 Apr 2022 Xuda Ding, Han Wang, Jianping He, Cailian Chen, Kostas Margellos, Antonis Papachristodoulou

Simulations demonstrates that BRSCA has a higher probability of finding feasible solutions, reduces the computation time by about 17. 4% and the energy cost by about four times compared to other methods in the literature.

Motion Planning

Stability of Non-linear Neural Feedback Loops using Sum of Squares

no code implementations8 Apr 2022 Matthew Newton, Antonis Papachristodoulou

These higher order Lyapunov functions are used in conjunction with higher order multipliers on the inequality and equality constraints that bound the neural network input-output properties.

Sparse Polynomial Optimisation for Neural Network Verification

no code implementations4 Feb 2022 Matthew Newton, Antonis Papachristodoulou

Depending on the complexity of these bounds, the computational time of the optimisation problem varies, with longer solve times often leading to tighter bounds.

Sparse sum-of-squares (SOS) optimization: A bridge between DSOS/SDSOS and SOS optimization for sparse polynomials

2 code implementations14 Jul 2018 Yang Zheng, Giovanni Fantuzzi, Antonis Papachristodoulou

Optimization over non-negative polynomials is fundamental for nonlinear systems analysis and control.

Optimization and Control Systems and Control

Decomposition and Completion of Sum-of-Squares Matrices

2 code implementations8 Apr 2018 Yang Zheng, Giovanni Fantuzzi, Antonis Papachristodoulou

We show that a subset of sparse SOS matrices with chordal sparsity patterns can be equivalently decomposed into a sum of multiple SOS matrices that are nonzero only on a principal submatrix.

Optimization and Control Systems and Control

Chordal decomposition in operator-splitting methods for sparse semidefinite programs

2 code implementations17 Jul 2017 Yang Zheng, Giovanni Fantuzzi, Antonis Papachristodoulou, Paul Goulart, Andrew Wynn

We employ chordal decomposition to reformulate a large and sparse semidefinite program (SDP), either in primal or dual standard form, into an equivalent SDP with smaller positive semidefinite (PSD) constraints.

Optimization and Control

Fast ADMM for homogeneous self-dual embedding of sparse SDPs

2 code implementations6 Nov 2016 Yang Zheng, Giovanni Fantuzzi, Antonis Papachristodoulou, Paul Goulart, Andrew Wynn

We propose an efficient first-order method, based on the alternating direction method of multipliers (ADMM), to solve the homogeneous self-dual embedding problem for a primal-dual pair of semidefinite programs (SDPs) with chordal sparsity.

Optimization and Control

Fast ADMM for Semidefinite Programs with Chordal Sparsity

2 code implementations20 Sep 2016 Yang Zheng, Giovanni Fantuzzi, Antonis Papachristodoulou, Paul Goulart, Andrew Wynn

We show that chordal decomposition can be applied to either the primal or the dual standard form of a sparse SDP, resulting in scaled versions of ADMM algorithms with the same computational cost.

Optimization and Control

Stochastic processes and feedback-linearisation for online identification and Bayesian adaptive control of fully-actuated mechanical systems

no code implementations18 Nov 2013 Jan-Peter Calliess, Antonis Papachristodoulou, Stephen J. Roberts

In contrast to previous work that has used stochastic processes for identification, we leverage the structural knowledge afforded by Lagrangian mechanics and learn the drift and control input matrix functions of the control-affine system separately.

SOSTOOLS Version 4.00 Sum of Squares Optimization Toolbox for MATLAB

3 code implementations17 Oct 2013 Antonis Papachristodoulou, James Anderson, Giorgio Valmorbida, Stephen Prajna, Pete Seiler, Pablo Parrilo

Specifically, polynomial and SOS variable declarations made using sossosvar, sospolyvar, sosmatrixvar, etc now return a new polynomial structure, dpvar.

Optimization and Control Mathematical Software Systems and Control

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