Samuel Coogan
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Ask, Reason, Assist: Decentralized Robot Collaboration via Language and Logic Open
Increased robot deployment, such as in warehousing, has revealed a need for seamless collaboration among heterogeneous robot teams to resolve unforeseen conflicts. To address this challenge, we propose a novel decentralized framework that …
Lightweight Tracking Control for Computationally Constrained Aerial Systems with the Newton-Raphson Method Open
We investigate the performance of a lightweight tracking controller, based on a flow version of the Newton-Raphson method, applied to a miniature blimp and a mid-size quadrotor. This tracking technique has been shown to enjoy theoretical g…
Accelerating Signal-Temporal-Logic-Based Task and Motion Planning of Bipedal Navigation using Benders Decomposition Open
Task and motion planning under Signal Temporal Logic constraints is known to be NP-hard. A common class of approaches formulates these hybrid problems, which involve discrete task scheduling and continuous motion planning, as mixed-integer…
Seeing, Saying, Solving: An LLM-to-TL Framework for Cooperative Robots Open
Increased robot deployment, such as in warehousing, has revealed a need for seamless collaboration among heterogeneous robot teams to resolve unforeseen conflicts. To address this challenge, we propose a novel, decentralized framework for …
Parametric Reachable Sets Via Controlled Dynamical Embeddings Open
In this work, we propose a new framework for reachable set computation through continuous evolution of a set of parameters and offsets which define a parametope, through the intersection of constraints. This results in a dynamical approach…
Uncertainty Estimators for Robust Backup Control Barrier Functions Open
Designing safe controllers is crucial and notoriously challenging for input-constrained safety-critical control systems. Backup control barrier functions offer an approach for the construction of safe controllers online by considering the …
Automatic and Scalable Safety Verification Using Interval Reachability With Subspace Sampling Open
Interval refinement is a technique for reducing the conservatism of traditional interval based reachability methods by lifting the system to a higher dimension using new auxiliary variables and exploiting the introduced structure through a…
A Linear Differential Inclusion for Contraction Analysis to Known Trajectories Open
Infinitesimal contraction analysis provides exponential convergence rates between arbitrary pairs of trajectories of a system by studying the system's linearization. An essentially equivalent viewpoint arises through stability analysis of …
A Global Coordinate-Free Approach to Invariant Contraction on Homogeneous Manifolds Open
In this work, we provide a global condition for contraction with respect to an invariant Riemannian metric on reductive homogeneous spaces. Using left-invariant frames, vector fields on the manifold are horizontally lifted to the ambient L…
Optimization-based Task and Motion Planning under Signal Temporal Logic Specifications using Logic Network Flow Open
This paper proposes an optimization-based task and motion planning framework, named "Logic Network Flow", to integrate signal temporal logic (STL) specifications into efficient mixed-binary linear programmings. In this framework, temporal …
Terrain-Aware Model Predictive Control of Heterogeneous Bipedal and Aerial Robot Coordination for Search and Rescue Tasks Open
Humanoid robots offer significant advantages for search and rescue tasks, thanks to their capability to traverse rough terrains and perform transportation tasks. In this study, we present a task and motion planning framework for search and…
Disturbance-Robust Backup Control Barrier Functions: Safety Under Uncertain Dynamics Open
Obtaining a controlled invariant set is crucial for safety-critical control with control barrier functions (CBFs) but is non-trivial for complex nonlinear systems and constraints. Backup control barrier functions allow such sets to be cons…
Newton-Raphson Flow for Aggressive Quadrotor Tracking Control Open
We apply the Newton-Raphson flow tracking controller to aggressive quadrotor flight and demonstrate that it achieves good tracking performance over a suite of benchmark trajectories, beating the native trajectory tracking controller in the…
Certified Robust Invariant Polytope Training in Neural Controlled ODEs Open
We consider a nonlinear control system modeled as an ordinary differential equation subject to disturbance, with a state feedback controller parameterized as a feedforward neural network. We propose a framework for training controllers wit…
A Unified Approach to Multi-task Legged Navigation: Temporal Logic Meets Reinforcement Learning Open
This study examines the problem of hopping robot navigation planning to achieve simultaneous goal-directed and environment exploration tasks. We consider a scenario in which the robot has mandatory goal-directed tasks defined using Linear …
LTL-D*: Incrementally Optimal Replanning for Feasible and Infeasible Tasks in Linear Temporal Logic Specifications Open
This paper presents an incremental replanning algorithm, dubbed LTL-D*, for temporal-logic-based task planning in a dynamically changing environment. Unexpected changes in the environment may lead to failures in satisfying a task specifica…
Bipedal Safe Navigation over Uncertain Rough Terrain: Unifying Terrain Mapping and Locomotion Stability Open
We study the problem of bipedal robot navigation in complex environments with uncertain and rough terrain. In particular, we consider a scenario in which the robot is expected to reach a desired goal location by traversing an environment w…
Efficient Reachable Sets on Lie Groups Using Lie Algebra Monotonicity and Tangent Intervals Open
In this paper, we efficiently compute overapproximating reachable sets for control systems evolving on Lie groups, building off results from monotone systems theory and geometric integration theory. We consider intervals in the tangent spa…
$\texttt{immrax}$: A Parallelizable and Differentiable Toolbox for Interval Analysis and Mixed Monotone Reachability in JAX Open
We present an implementation of interval analysis and mixed monotone interval reachability analysis as function transforms in Python, fully composable with the computational framework JAX. The resulting toolbox inherits several key feature…
GreenEVT: Greensboro Electric Vehicle Testbed Open
The ongoing electrification of the transportation fleet will increase the\nload on the electric power grid. Since both the transportation network and the\npower grid already experience periods of significant stress, joint analyses of\nboth…
Interval Signal Temporal Logic from Natural Inclusion Functions Open
We propose an interval extension of Signal Temporal Logic (STL) called Interval Signal Temporal Logic (\ISTL). Given an STL formula, we consider an interval inclusion function for each of its predicates. Then, we use minimal inclusion func…
A Contracting Dynamical System Perspective toward Interval Markov Decision Processes Open
Interval Markov decision processes are a class of Markov models where the transition probabilities between the states belong to intervals. In this paper, we study the problem of efficient estimation of the optimal policies in Interval Mark…
Forward Invariance in Neural Network Controlled Systems Open
We present a framework based on interval analysis and monotone systems theory to certify and search for forward invariant sets in nonlinear systems with neural network controllers. The framework (i) constructs localized first-order inclusi…
Safe Schedule Verification for Urban Air Mobility Networks With Node Closures Open
In urban air mobility (UAM) networks, takeoff and landing sites, called vertiports, are likely to experience intermittent closures due to, e.g., adverse weather. To ensure safety, all in-flight urban air vehicles (UAVs) in a UAM network mu…
Efficient Interaction-Aware Interval Analysis of Neural Network Feedback Loops Open
In this paper, we propose a computationally efficient framework for interval reachability of systems with neural network controllers. Our approach leverages inclusion functions for the open-loop system and the neural network controller to …
A Toolbox for Fast Interval Arithmetic in numpy with an Application to Formal Verification of Neural Network Controlled Systems Open
In this paper, we present a toolbox for interval analysis in numpy, with an application to formal verification of neural network controlled systems. Using the notion of natural inclusion functions, we systematically construct interval boun…
The Strong Integral Input-to-State Stability Property in Dynamical Flow Networks Open
Dynamical flow networks serve as macroscopic models for, e.g., transportation networks, queuing networks, and distribution networks. While the flow dynamics in such networks follow the conservation of mass on the links, the outflow from ea…
Contraction-Guided Adaptive Partitioning for Reachability Analysis of Neural Network Controlled Systems Open
In this paper, we present a contraction-guided adaptive partitioning algorithm for improving interval-valued robust reachable set estimates in a nonlinear feedback loop with a neural network controller and disturbances. Based on an estimat…
View article: Runtime Assurance for Safety-Critical Systems: An Introduction to Safety Filtering Approaches for Complex Control Systems
Runtime Assurance for Safety-Critical Systems: An Introduction to Safety Filtering Approaches for Complex Control Systems Open
More than three miles above the Arizona desert, an F-16 student pilot experienced a gravity-induced loss of consciousness, passing out while turning at nearly 9Gs (nine times the force of gravity), flying over 400 kn (over 460 mi/h). With …