Search Results for author: Frank Allgöwer

Found 72 papers, 6 papers with code

Bootstrapping Guarantees: Stability and Performance Analysis for Dynamic Encrypted Control

no code implementations27 Mar 2024 Sebastian Schlor, Frank Allgöwer

By recognizing the bootstrapping errors occurring in the controller's state as an uncertainty in the robust control framework, we can provide stability and performance guarantees for the whole encrypted control system.

Collision Avoidance Safety Filter for an Autonomous E-Scooter using Ultrasonic Sensors

no code implementations22 Mar 2024 Robin Strässer, Marc Seidel, Felix Brändle, David Meister, Raffaele Soloperto, David Hambach Ferrer, Frank Allgöwer

In this paper, we propose a collision avoidance safety filter for autonomous electric scooters to enable safe operation of such vehicles in pedestrian areas.

Collision Avoidance

SafEDMD: A certified learning architecture tailored to data-driven control of nonlinear dynamical systems

no code implementations5 Feb 2024 Robin Strässer, Manuel Schaller, Karl Worthmann, Julian Berberich, Frank Allgöwer

The Koopman operator serves as the theoretical backbone for machine learning of dynamical control systems, where the operator is heuristically approximated by extended dynamic mode decomposition (EDMD).

Novel Quadratic Constraints for Extending LipSDP beyond Slope-Restricted Activations

no code implementations25 Jan 2024 Patricia Pauli, Aaron Havens, Alexandre Araujo, Siddharth Garg, Farshad Khorrami, Frank Allgöwer, Bin Hu

However, a direct application of LipSDP to the resultant residual ReLU networks is conservative and even fails in recovering the well-known fact that the MaxMin activation is 1-Lipschitz.

Towards non-stochastic targeted exploration

no code implementations10 Dec 2023 Janani Venkatasubramanian, Johannes Köhler, Mark Cannon, Frank Allgöwer

We present a novel targeted exploration strategy for linear time-invariant systems without stochastic assumptions on the noise, i. e., without requiring independence or zero mean, allowing for deterministic model misspecifications.

Koopman-based feedback design with stability guarantees

no code implementations3 Dec 2023 Robin Strässer, Manuel Schaller, Karl Worthmann, Julian Berberich, Frank Allgöwer

We present a method to design a state-feedback controller ensuring exponential stability for nonlinear systems using only measurement data.

Scheduling

Decrypting Nonlinearity: Koopman Interpretation and Analysis of Cryptosystems

no code implementations21 Nov 2023 Robin Strässer, Sebastian Schlor, Frank Allgöwer

Our results on the required lifting dimension are in line with the intractability of brute-force attacks.

Performance implications of different $p$-norms in level-triggered sampling

no code implementations7 Sep 2023 David Meister, Frank Allgöwer

We therefore demonstrate that the performance degradation found in the distributed setting originates from the triggering rule and not from the considered cooperative control goal.

Analysis and design of model predictive control frameworks for dynamic operation -- An overview

no code implementations6 Jul 2023 Johannes Köhler, Matthas A. Müller, Frank Allgöwer

This article provides an overview of model predictive control (MPC) frameworks for dynamic operation of nonlinear constrained systems.

Model Predictive Control

On $\ell_2$-performance of weakly-hard real-time control systems

no code implementations13 May 2023 Marc Seidel, Simon Lang, Frank Allgöwer

This paper considers control systems with failures in the feedback channel, that occasionally lead to loss of the control input signal.

Stochastic Model Predictive Control using Initial State and Variance Interpolation

no code implementations14 Apr 2023 Henning Schlüter, Frank Allgöwer

We present a Stochastic Model Predictive Control (SMPC) framework for linear systems subject to Gaussian disturbances.

Model Predictive Control

Robust data-driven control for nonlinear systems using the Koopman operator

no code implementations7 Apr 2023 Robin Strässer, Julian Berberich, Frank Allgöwer

Data-driven analysis and control of dynamical systems have gained a lot of interest in recent years.

Distributed Model Predictive Control for Periodic Cooperation of Multi-Agent Systems

no code implementations6 Apr 2023 Matthias Köhler, Matthias A. Müller, Frank Allgöwer

We show that under suitable assumptions, the agents can incrementally move their artificial output trajectories towards the cooperative goal, and, hence, their closed-loop output trajectories asymptotically achieve it.

Model Predictive Control

Self-triggered output feedback control for nonlinear networked control systems based on hybrid Lyapunov functions

no code implementations22 Mar 2023 Michael Hertneck, Frank Allgöwer

Most approaches for self-triggered control (STC) of nonlinear networked control systems (NCS) require measurements of the full system state to determine transmission times.

Time- versus Event-Triggered Consensus of a Single-Integrator Multi-Agent System

no code implementations20 Mar 2023 David Meister, Frank Aurzada, Mikhail A. Lifshits, Frank Allgöwer

Inspired by existing performance analyses for the single-loop case, we provide a first fundamental performance comparison of time- and event-triggered control in a distributed multi-agent consensus setting.

Lipschitz-bounded 1D convolutional neural networks using the Cayley transform and the controllability Gramian

1 code implementation20 Mar 2023 Patricia Pauli, Ruigang Wang, Ian R. Manchester, Frank Allgöwer

We establish a layer-wise parameterization for 1D convolutional neural networks (CNNs) with built-in end-to-end robustness guarantees.

Data-driven Dissipativity Analysis of Linear Parameter-Varying Systems

no code implementations17 Mar 2023 Chris Verhoek, Julian Berberich, Sofie Haesaert, Frank Allgöwer, Roland Tóth

We derive direct data-driven dissipativity analysis methods for Linear Parameter-Varying (LPV) systems using a single sequence of input-scheduling-output data.

Scheduling

Convolutional Neural Networks as 2-D systems

no code implementations6 Mar 2023 Dennis Gramlich, Patricia Pauli, Carsten W. Scherer, Frank Allgöwer, Christian Ebenbauer

This paper introduces a novel representation of convolutional Neural Networks (CNNs) in terms of 2-D dynamical systems.

Sequential learning and control: Targeted exploration for robust performance

no code implementations19 Jan 2023 Janani Venkatasubramanian, Johannes Köhler, Julian Berberich, Frank Allgöwer

This provides an a priori upper bound on the remaining model uncertainty after exploration, which can further be leveraged in a gain-scheduling controller design that guarantees robust performance.

Scheduling

Linear Data-Driven Economic MPC with Generalized Terminal Constraint

no code implementations2 Dec 2022 Yifan Xie, Julian Berberich, Frank Allgöwer

By employing a generalized terminal constraint with artificial equilibrium, the scheme does not require prior knowledge of the optimal equilibrium.

LEMMA Model Predictive Control

Lipschitz constant estimation for 1D convolutional neural networks

no code implementations28 Nov 2022 Patricia Pauli, Dennis Gramlich, Frank Allgöwer

In this work, we propose a dissipativity-based method for Lipschitz constant estimation of 1D convolutional neural networks (CNNs).

Koopman interpretation and analysis of a public-key cryptosystem: Diffie-Hellman key exchange

no code implementations21 Nov 2022 Sebastian Schlor, Robin Strässer, Frank Allgöwer

In this paper, we introduce a new perspective on cryptosystems by interpreting the Diffie-Hellman key exchange as a nonlinear dynamical system.

Robust peak-to-peak gain analysis using integral quadratic constraints

no code implementations17 Nov 2022 Lukas Schwenkel, Johannes Köhler, Matthias A. Müller, Frank Allgöwer

This work provides a framework to compute an upper bound on the robust peak-to-peak gain of discrete-time uncertain linear systems using integral quadratic constraints (IQCs).

Shared Network Effects in Time- versus Event-Triggered Consensus of a Single-Integrator Multi-Agent System

no code implementations15 Nov 2022 David Meister, Frank Dürr, Frank Allgöwer

While this motivation is commonly used also for multi-agent systems, a theoretical analysis of the impact of network effects on the performance of event- and time-triggered control for such distributed systems is currently missing.

Data-driven Nonlinear Predictive Control for Feedback Linearizable Systems

no code implementations11 Nov 2022 Mohammad Alsalti, Victor G. Lopez, Julian Berberich, Frank Allgöwer, Matthias A. Müller

We present a data-driven nonlinear predictive control approach for the class of discrete-time multi-input multi-output feedback linearizable nonlinear systems.

Distributed MPC for Self-Organized Cooperation of Multi-Agent Systems

no code implementations18 Oct 2022 Matthias Köhler, Matthias A. Müller, Frank Allgöwer

We present a sequential distributed model predictive control (MPC) scheme for cooperative control of multi-agent systems with dynamically decoupled heterogeneous nonlinear agents subject to individual constraints.

Distributed Optimization Model Predictive Control

Data-Driven Control of Distributed Event-Triggered Network Systems

no code implementations22 Aug 2022 Xin Wang, Jian Sun, Gang Wang, Frank Allgöwer, Jie Chen

The present paper deals with data-driven event-triggered control of a class of unknown discrete-time interconnected systems (a. k. a.

Analysis of Time- versus Event-Triggered Consensus for a Single-Integrator Multi-Agent System

no code implementations17 Jun 2022 David Meister, Frank Aurzada, Mikhail A. Lifshits, Frank Allgöwer

Contrary to the non-cooperative setting, we prove that event-triggered control performs worse than time-triggered control beyond a certain number of agents in this setup.

Stability in data-driven MPC: an inherent robustness perspective

no code implementations24 May 2022 Julian Berberich, Johannes Köhler, Matthias A. Müller, Frank Allgöwer

Moreover, we discuss how the presented proof technique allows to show closed-loop stability of a variety of DD-MPC schemes with noisy data, as long as the corresponding model-based MPC is inherently robust.

LEMMA Model Predictive Control

Linearly discounted economic MPC without terminal conditions for periodic optimal operation

no code implementations6 May 2022 Lukas Schwenkel, Alexander Hadorn, Matthias A. Müller, Frank Allgöwer

Under standard dissipativity and controllability assumptions, we can prove that the resulting linearly discounted economic MPC without terminal conditions achieves optimal asymptotic average performance up to an error that vanishes with growing prediction horizons.

Model Predictive Control

Bounding the difference between model predictive control and neural networks

no code implementations13 Apr 2022 Ross Drummond, Stephen R. Duncan, Matthew C. Turner, Patricia Pauli, Frank Allgöwer

There is a growing debate on whether the future of feedback control systems will be dominated by data-driven or model-driven approaches.

Model Predictive Control

Self-triggered MPC robust to bounded packet loss via a min-max approach: extended version

no code implementations1 Apr 2022 Stefan Wildhagen, Matthias Pezzutto, Luca Schenato, Frank Allgöwer

Networked Control Systems typically come with a limited communication bandwidth and thus require special care when designing the underlying control and triggering law.

Model Predictive Control

A novel constraint tightening approach for robust data-driven predictive control

no code implementations14 Mar 2022 Christian Klöppelt, Julian Berberich, Frank Allgöwer, Matthias A. Müller

This allows the entire scheme to be set up using only a priori measured data and knowledge of an upper bound on the system order.

LEMMA Model Predictive Control

Stochastic Model Predictive Control using Initial State Optimization

no code implementations3 Mar 2022 Henning Schlüter, Frank Allgöwer

We propose a stochastic MPC scheme using an optimization over the initial state for the predicted trajectory.

Model Predictive Control

Data-driven distributed MPC of dynamically coupled linear systems

no code implementations25 Feb 2022 Matthias Köhler, Julian Berberich, Matthias A. Müller, Frank Allgöwer

In this paper, we present a data-driven distributed model predictive control (MPC) scheme to stabilise the origin of dynamically coupled discrete-time linear systems subject to decoupled input constraints.

LEMMA Model Predictive Control

Model-Based and Data-Driven Control of Event- and Self-Triggered Discrete-Time LTI Systems

no code implementations16 Feb 2022 Xin Wang, Julian Berberich, Jian Sun, Gang Wang, Frank Allgöwer, Jie Chen

To this end, we begin by presenting a dynamic event-triggering scheme (ETS) based on periodic sampling, and a discrete-time looped-functional approach, through which a model-based stability condition is derived.

STS

Dynamic self-triggered control for nonlinear systems with delays

no code implementations9 Feb 2022 Michael Hertneck, Frank Allgöwer

Self-triggered control (STC) is a resource efficient approach to determine sampling instants for Networked Control Systems (NCS).

Neural network training under semidefinite constraints

1 code implementation3 Jan 2022 Patricia Pauli, Niklas Funcke, Dennis Gramlich, Mohamed Amine Msalmi, Frank Allgöwer

This paper is concerned with the training of neural networks (NNs) under semidefinite constraints, which allows for NN training with robustness and stability guarantees.

Robust dynamic self-triggered control for nonlinear systems using hybrid Lyapunov functions

no code implementations8 Nov 2021 Michael Hertneck, Frank Allgöwer

In the framework, a dynamic variable is used in addition to current state information to determine the next sampling instant, rendering the STC mechanism dynamic.

Data-driven Control of Dynamic Event-triggered Systems with Delays

no code implementations25 Oct 2021 Xin Wang, Jian Sun, Julian Berberich, Gang Wang, Frank Allgöwer, Jie Chen

Data-based representations for time-invariant linear systems with known or unknown system input matrices are first developed, along with a novel class of dynamic triggering schemes for sampled-data systems with time delays.

Data-driven system analysis of nonlinear systems using polynomial approximation

no code implementations25 Aug 2021 Tim Martin, Frank Allgöwer

To tackle these drawbacks, we establish a polynomial representation of nonlinear functions based on a polynomial sector by Taylor's theorem and a set-membership for Taylor polynomials.

Uncertainties and output feedback in rollout event-triggered control

no code implementations20 Aug 2021 Stefan Wildhagen, Frank Allgöwer

Rollout ETC addresses this issue by using a triggering and control law that is implicitly defined by the solution to an optimal control problem (OCP), instead of an explicit one as in classical ETC.

Model Predictive Control

Rollout event-triggered control: reconciling event- and time-triggered control

no code implementations6 Aug 2021 Stefan Wildhagen, Frank Dürr, Frank Allgöwer

Event-triggered control (ETC) and time-triggered control (TTC), the classical concepts to determine the transmission instants for networked control systems, each come with drawbacks: It is difficult to tune ETC such that a certain bandwidth is respected, whereas TTC cannot adapt the sampling interval to the current state of the control system.

Scheduling

Data-Driven Reachability Analysis from Noisy Data

1 code implementation15 May 2021 Amr Alanwar, Anne Koch, Frank Allgöwer, Karl Henrik Johansson

We consider the problem of computing reachable sets directly from noisy data without a given system model.

Robust output feedback model predictive control using online estimation bounds

no code implementations7 May 2021 Johannes Köhler, Matthias A. Müller, Frank Allgöwer

Robust constraint satisfaction is guaranteed by suitably incorporating these online validated bounds on the estimation error in a homothetic tube based MPC formulation.

Model Predictive Control

Linear systems with neural network nonlinearities: Improved stability analysis via acausal Zames-Falb multipliers

1 code implementation31 Mar 2021 Patricia Pauli, Dennis Gramlich, Julian Berberich, Frank Allgöwer

In this paper, we analyze the stability of feedback interconnections of a linear time-invariant system with a neural network nonlinearity in discrete time.

Computational Efficiency

Multi-party computation enables secure polynomial control based solely on secret-sharing

no code implementations30 Mar 2021 Sebastian Schlor, Michael Hertneck, Stefan Wildhagen, Frank Allgöwer

As homomorphic encryptions are much more computationally demanding than secret sharing, they make up for a tremendous amount of the overall computational demand of this scheme.

Improved stability conditions for systems under aperiodic sampling: model- and data-based analysis

no code implementations26 Mar 2021 Stefan Wildhagen, Julian Berberich, Matthias Hirche, Frank Allgöwer

Recently, model- and data-based stability conditions for such systems were obtained by rewriting them as an interconnection of a linear time-invariant system and a delay operator, and subsequently, performing a robust stability analysis using a known bound on the gain of this operator.

Data-driven inference on optimal input-output properties of polynomial systems with focus on nonlinearity measures

no code implementations18 Mar 2021 Tim Martin, Frank Allgöwer

In the context of dynamical systems, nonlinearity measures quantify the strength of nonlinearity by means of the distance of their input-output behaviour to a set of linear input-output mappings.

Data-Based System Analysis and Control of Flat Nonlinear Systems

no code implementations4 Mar 2021 Mohammad Alsalti, Julian Berberich, Victor G. Lopez, Frank Allgöwer, Matthias A. Müller

Willems et al. showed that all input-output trajectories of a discrete-time linear time-invariant system can be obtained using linear combinations of time shifts of a single, persistently exciting, input-output trajectory of that system.

Transient Performance of Tube-based Robust Economic Model Predictive Control

no code implementations18 Feb 2021 Christian Klöppelt, Lukas Schwenkel, Frank Allgöwer, Matthias A. Müller

In this paper, we provide non-averaged and transient performance guarantees for recently developed, tube-based robust economic model predictive control (MPC) schemes.

Model Predictive Control

Data-Driven Controller Design via Finite-Horizon Dissipativity

no code implementations15 Jan 2021 Nils Wieler, Julian Berberich, Anne Koch, Frank Allgöwer

Given one open-loop measured trajectory of a single-input single-output discrete-time linear time-invariant system, we present a framework for data-driven controller design for closed-loop finite-horizon dissipativity.

On the design of terminal ingredients for data-driven MPC

no code implementations14 Jan 2021 Julian Berberich, Johannes Köhler, Matthias A. Müller, Frank Allgöwer

We present a model predictive control (MPC) scheme to control linear time-invariant systems using only measured input-output data and no model knowledge.

Optimization and Control Systems and Control Systems and Control

Stability and performance in MPC using a finite-tail cost

no code implementations12 Jan 2021 Johannes Köhler, Frank Allgöwer

In this paper, we provide a stability and performance analysis of model predictive control (MPC) schemes based on finite-tail costs.

Model Predictive Control

Data-driven analysis and controller design for discrete-time systems under aperiodic sampling

no code implementations4 Jan 2021 Stefan Wildhagen, Julian Berberich, Michael Hertneck, Frank Allgöwer

This article is concerned with data-driven analysis of discrete-time systems under aperiodic sampling, and in particular with a data-driven estimation of the maximum sampling interval (MSI).

Offset-free setpoint tracking using neural network controllers

no code implementations23 Nov 2020 Patricia Pauli, Johannes Köhler, Julian Berberich, Anne Koch, Frank Allgöwer

In this paper, we present a method to analyze local and global stability in offset-free setpoint tracking using neural network controllers and we provide ellipsoidal inner approximations of the corresponding region of attraction.

Data-Driven Control of Nonlinear Systems: Beyond Polynomial Dynamics

no code implementations23 Nov 2020 Robin Strässer, Julian Berberich, Frank Allgöwer

While most existing approaches focus on systems with polynomial dynamics, our approach allows to design controllers for unknown systems with rational or general non-polynomial dynamics.

Data-Driven Reachability Analysis Using Matrix Zonotopes

1 code implementation17 Nov 2020 Amr Alanwar, Anne Koch, Frank Allgöwer, Karl Henrik Johansson

In this paper, we propose a data-driven reachability analysis approach for unknown system dynamics.

Combining Prior Knowledge and Data for Robust Controller Design

no code implementations11 Sep 2020 Julian Berberich, Carsten W. Scherer, Frank Allgöwer

We present a framework for systematically combining data of an unknown linear time-invariant system with prior knowledge on the system matrices or on the uncertainty for robust controller design.

A Simple Approach to Increase the Maximum Allowable Transmission Interval

no code implementations5 Jun 2020 Michael Hertneck, Frank Allgöwer

When designing Networked Control Systems (NCS), the maximum allowable transmission interval (MATI) is an important quantity, as it provides the admissible time between two transmission instants.

Constrained nonlinear output regulation using model predictive control -- extended version

no code implementations25 May 2020 Johannes Köhler, Matthias A. Müller, Frank Allgöwer

The paper also contains novel results for MPC without terminal constraints with positive semidefinite input/output stage costs that are of independent interest.

Model Predictive Control

Robust and optimal predictive control of the COVID-19 outbreak

no code implementations7 May 2020 Johannes Köhler, Lukas Schwenkel, Anne Koch, Julian Berberich, Patricia Pauli, Frank Allgöwer

Our theoretical findings support various recent studies by showing that 1) adaptive feedback strategies are required to reliably contain the COVID-19 outbreak, 2) well-designed policies can significantly reduce the number of fatalities compared to simpler ones while keeping the amount of social distancing measures on the same level, and 3) imposing stronger social distancing measures early on is more effective and cheaper in the long run than opening up too soon and restoring stricter measures at a later time.

Model Predictive Control

Training robust neural networks using Lipschitz bounds

2 code implementations6 May 2020 Patricia Pauli, Anne Koch, Julian Berberich, Paul Kohler, Frank Allgöwer

More specifically, we design an optimization scheme based on the Alternating Direction Method of Multipliers that minimizes not only the training loss of an NN but also its Lipschitz constant resulting in a semidefinite programming based training procedure that promotes robustness.

Robust Dual Control based on Gain Scheduling

no code implementations9 Apr 2020 Janani Venkatasubramanian, Johannes Köhler, Julian Berberich, Frank Allgöwer

We present a novel strategy for robust dual control of linear time-invariant systems based on gain scheduling with performance guarantees.

Scheduling

Robust Constraint Satisfaction in Data-Driven MPC

no code implementations15 Mar 2020 Julian Berberich, Johannes Köhler, Matthias A. Müller, Frank Allgöwer

We propose a purely data-driven model predictive control (MPC) scheme to control unknown linear time-invariant systems with guarantees on stability and constraint satisfaction in the presence of noisy data.

Model Predictive Control

Data-Driven Tracking MPC for Changing Setpoints

no code implementations21 Oct 2019 Julian Berberich, Johannes Köhler, Matthias A. Müller, Frank Allgöwer

We propose a data-driven tracking model predictive control (MPC) scheme to control unknown discrete-time linear time-invariant systems.

Model Predictive Control

Model-Free Practical Cooperative Control for Diffusively Coupled Systems

no code implementations12 Jun 2019 Miel Sharf, Anne Koch, Daniel Zelazo, Frank Allgöwer

In this paper, we develop a data-based controller design framework for diffusively coupled systems with guaranteed convergence to an $\epsilon$-neighborhood of the desired formation.

Data-Driven Model Predictive Control with Stability and Robustness Guarantees

no code implementations11 Jun 2019 Julian Berberich, Johannes Köhler, Matthias A. Müller, Frank Allgöwer

First, we prove exponential stability of a nominal data-driven MPC scheme with terminal equality constraints in the case of no measurement noise.

Model Predictive Control

Learning an Approximate Model Predictive Controller with Guarantees

no code implementations11 Jun 2018 Michael Hertneck, Johannes Köhler, Sebastian Trimpe, Frank Allgöwer

A supervised learning framework is proposed to approximate a model predictive controller (MPC) with reduced computational complexity and guarantees on stability and constraint satisfaction.

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