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Spatiotemporal Tubes based Controller Synthesis against Omega-Regular Specifications for Unknown Systems

Ratnangshu Das, Aiman Aatif Bayezeed, Pushpak Jagtap

TL;DR

The paper addresses synthesis of approximation-free, closed-form controllers for unknown nonlinear MIMO systems to enforce $\omega$-regular specifications recognized by non-deterministic Büchi automata (NBA). It introduces a discretization-free, spatiotemporal tubes (STT) framework that decomposes NBA specifications into a sequence of reach-avoid tasks, solves each task with a closed-form RA controller, and stitches them into a hybrid policy that provably satisfies the NBA language. The approach extends to general strict-feedback MIMO systems with unknown dynamics, relaxing restrictive obstacle-position assumptions and providing a scalable, real-time capable solution demonstrated on a 2R manipulator and an omnidirectional mobile robot. This work advances formal control by delivering an approximation-free, hybrid control synthesis method for complex, infinite-horizon specifications with unknown dynamics, enabling robust autonomous behavior under omega-regular constraints.

Abstract

This paper provides a discretization-free solution to the synthesis of approx-imation-free closed-form controllers for unknown nonlinear systems to enforce complex properties expressed by $ω$-regular languages, as recognized by Non-deterministic Büchi Automata (NBA). In order to solve this problem, we first decompose NBA into a sequence of reach-avoid problems, which are solved using the Spatiotemporal Tubes (STT) approach. Controllers for each reach-avoid task are then integrated into a hybrid policy that ensures the fulfillment of the desired $ω$-regular properties. We validate our method through omnidirectional robot navigation and manipulator control case studies.

Spatiotemporal Tubes based Controller Synthesis against Omega-Regular Specifications for Unknown Systems

TL;DR

The paper addresses synthesis of approximation-free, closed-form controllers for unknown nonlinear MIMO systems to enforce -regular specifications recognized by non-deterministic Büchi automata (NBA). It introduces a discretization-free, spatiotemporal tubes (STT) framework that decomposes NBA specifications into a sequence of reach-avoid tasks, solves each task with a closed-form RA controller, and stitches them into a hybrid policy that provably satisfies the NBA language. The approach extends to general strict-feedback MIMO systems with unknown dynamics, relaxing restrictive obstacle-position assumptions and providing a scalable, real-time capable solution demonstrated on a 2R manipulator and an omnidirectional mobile robot. This work advances formal control by delivering an approximation-free, hybrid control synthesis method for complex, infinite-horizon specifications with unknown dynamics, enabling robust autonomous behavior under omega-regular constraints.

Abstract

This paper provides a discretization-free solution to the synthesis of approx-imation-free closed-form controllers for unknown nonlinear systems to enforce complex properties expressed by -regular languages, as recognized by Non-deterministic Büchi Automata (NBA). In order to solve this problem, we first decompose NBA into a sequence of reach-avoid problems, which are solved using the Spatiotemporal Tubes (STT) approach. Controllers for each reach-avoid task are then integrated into a hybrid policy that ensures the fulfillment of the desired -regular properties. We validate our method through omnidirectional robot navigation and manipulator control case studies.

Paper Structure

This paper contains 17 sections, 3 theorems, 20 equations, 4 figures.

Key Result

Theorem 3.1

Given an unknown nonlinear MIMO system in eqn:sysdyn satisfying assumptions assum:lip and assum:pd, a reach-avoid task, and corresponding STTs, if $y(0)$ is within the spatiotemporal tubes at time $t=0$, i.e., $\gamma_{1,i,L}(0) < y_i(0) < \gamma_{1,i,U}(0), \forall i \in [1;n]$, then the closed-for will satisfy eqn:ppc, guiding the output $y(t)$ to the target $T$, while avoiding the unsafe set $U

Figures (4)

  • Figure 1: Illustrative automata representing triplets
  • Figure 2: 2R Manipulator NBA
  • Figure 3: Trajectory of the 2R manipulator
  • Figure 4: (a) Trajectory of the Mobile robot in 2D plane. (b) Tubes generated for each axis and the trajectory

Theorems & Definitions (11)

  • Definition 2.1: buchi1990decision
  • Remark 2.2
  • Definition 2.3: wongpiromsarn2015automata
  • Definition 2.4
  • Theorem 3.1
  • Proof 3.2
  • Remark 3.3
  • Lemma 3.4
  • Proof 3.5
  • Theorem 3.6
  • ...and 1 more