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Towards Bridging the Gap between High-Level Reasoning and Execution on Robots

Till Hofmann

TL;DR

The work addresses the gap between high-level planning and real-time robot execution under uncertainty. It introduces t-ESG, a metric-time extension of ESG/Golog, and shows how robot self-models can be represented as timed automata, enabling MTL-based specifications and synthesis. It establishes decidability results for finite-domain settings, outlines offline and online plan-transformation pipelines, and develops a region-based, WSTS-enabled synthesis framework using ATA/MTL translations and timed games. The framework supports verification and controller synthesis, with practical applicability to real robotic platforms while carefully avoiding undecidability through clock-restriction strategies and abstraction mechanisms. Overall, the approach provides a principled pathway to guarantee timing-constrained behaviors in autonomous robots through formal logic, automata, and game-theoretic synthesis.

Abstract

When reasoning about actions, e.g., by means of task planning or agent programming with Golog, the robot's actions are typically modeled on an abstract level, where complex actions such as picking up an object are treated as atomic primitives with deterministic effects and preconditions that only depend on the current state. However, when executing such an action on a robot it can no longer be seen as a primitive. Instead, action execution is a complex task involving multiple steps with additional temporal preconditions and timing constraints. Furthermore, the action may be noisy, e.g., producing erroneous sensing results and not always having the desired effects. While these aspects are typically ignored in reasoning tasks, they need to be dealt with during execution. In this thesis, we propose several approaches towards closing this gap.

Towards Bridging the Gap between High-Level Reasoning and Execution on Robots

TL;DR

The work addresses the gap between high-level planning and real-time robot execution under uncertainty. It introduces t-ESG, a metric-time extension of ESG/Golog, and shows how robot self-models can be represented as timed automata, enabling MTL-based specifications and synthesis. It establishes decidability results for finite-domain settings, outlines offline and online plan-transformation pipelines, and develops a region-based, WSTS-enabled synthesis framework using ATA/MTL translations and timed games. The framework supports verification and controller synthesis, with practical applicability to real robotic platforms while carefully avoiding undecidability through clock-restriction strategies and abstraction mechanisms. Overall, the approach provides a principled pathway to guarantee timing-constrained behaviors in autonomous robots through formal logic, automata, and game-theoretic synthesis.

Abstract

When reasoning about actions, e.g., by means of task planning or agent programming with Golog, the robot's actions are typically modeled on an abstract level, where complex actions such as picking up an object are treated as atomic primitives with deterministic effects and preconditions that only depend on the current state. However, when executing such an action on a robot it can no longer be seen as a primitive. Instead, action execution is a complex task involving multiple steps with additional temporal preconditions and timing constraints. Furthermore, the action may be noisy, e.g., producing erroneous sensing results and not always having the desired effects. While these aspects are typically ignored in reasoning tasks, they need to be dealt with during execution. In this thesis, we propose several approaches towards closing this gap.
Paper Structure (78 sections, 15 theorems, 124 equations, 21 figures, 6 tables, 7 algorithms)

This paper contains 78 sections, 15 theorems, 124 equations, 21 figures, 6 tables, 7 algorithms.

Key Result

theorem 3.1

Let $\mathcal{A}$ be ATA and $\mathcal{B}$ be TA. Then the language emptiness problem $\mathcal{L}\xspace^*(\mathcal{A}) = \emptyset$ and the language inclusion problem $\mathcal{L}\xspace^*(\mathcal{A}) \subseteq \mathcal{L}\xspace^*(\mathcal{B})$ are both decidable.

Figures (21)

  • Figure 1: Two different robots with similar capabilities. From a high-level perspective, both robots are the same: They can move around and pick up or put down objects. However, when considering the actual robot, they clearly differ in many ways. For example, while Caesar has an arm that allows it to reach far onto the table, the logistics robot needs to move close to the machine in order to put down its workpiece.
  • Figure 2: A *TA that models a robot camera. If the camera is off, the robot may start booting the camera, which takes at least 4 and at most 6. If it is on, the robot may instantaneously turn the camera off again.
  • Figure 3: The tree of situations for a model with $n$ actions (adapted from reiterKnowledgeActionLogical2001).
  • Figure 4: A robot driving towards a wall belleReasoningProbabilitiesUnbounded2017. The robot can measure the distance to the wall with its action $\mathit{sonar}$ and it can move towards the wall with the action $\mathit{move}$. Both actions are noisy: the sonar does not measure the exact distance and the $\mathit{move}$ action may move with further or shorter than intended.
  • Figure 5: *LTL operators (adapted from baierPrinciplesModelChecking2008.)
  • ...and 16 more figures

Theorems & Definitions (123)

  • definition 3.1: Formulas of *MTL
  • definition 3.2: Timed Words
  • definition 3.3: Point-based Semantics of *MTL
  • definition 3.4: LTS
  • example 3.1: LTS
  • definition 3.5: Clock constraint
  • example 3.2
  • definition 3.6: Clock valuation
  • definition 3.7: Clock constraint satisfaction
  • example 3.3
  • ...and 113 more