Control Synthesis for Multi-Agent Systems under Coupled Signal Temporal Logic Tasks
A Top-Down Model Predictive Approach
Time: Fri 2024-06-14 15.00
Location: D1, Lindstedtsvägen 17, Stockholm
Video link: https://kth-se.zoom.us/j/61735978944
Language: English
Subject area: Electrical Engineering
Doctoral student: Maria Charitidou , Reglerteknik
Opponent: Professor Hadas Kress-Gazit, Cornell University, Ithaca, NY, USA
Supervisor: Dimos V. Dimarogonas, Reglerteknik
QC 20240521
Abstract
Nowadays autonomous systems are expected to perform complex tasks that go beyond traditional control objectives such as setpoint tracking or consensus of multi-agent systems. More specifically, in a plethora of applications agents often need to collaborate with their peers in order to perform a variety of spatial tasks within strict deadlines. Spatio-temporal tasks of this form can be easily expressed in Signal Temporal Logic (STL), a predicate language that allow us to formally introduce time-constrained tasks defined as Boolean combinations of simpler subformulas involving temporal operators such as the always, eventually and until operator.
In this thesis we consider the problem of control under high-level specifications for single as well as multi-agent systems. Our work is divided in three parts. In the first part we consider spatio-temporal objectives expressed in Signal Temporal Logic and propose feedback control laws guaranteeing the satisfaction of the tasks under consideration using various levels of state information. First, motivated by multi-platoon coordination scenarios we design a nonlinear feedback control law ensuring minimal violation of a STL task involving merging and splitting of given pairs of platoons when the satisfaction of the task can not be achieved due to actuation limitations. Next, we propose a novel control barrier function to encode the satisfaction of a STL fragment involving disjunctions of selected STL tasks. As a further contribution, we propose a distributed switching feedback control law for the satisfaction of a given set of relative position-based STL tasks that is based on the prescribed performance control philosophy.
In the second part model predictive control schemes are designed for single and multi-agent systems subject to STL, input and state constraints. Contrary to state of the art, the proposed approaches encode the satisfaction of the STL tasks under consideration using continuous variables. In addition, the proposed MPC schemes are shown to be recursively feasible thanks to appropriately designed terminal ingredients while the planning horizon of the related problems can be chosen arbitrarily small and independent of the STL task. To deal with collaborative tasks often present in multi-agent setups we present a novel approach to decompose the tasks into agent-dependent objectives allowing the design of non-cooperative control schemes that guarantee the satisfaction of the initial task with limited communication. Finally, a sequential distributed MPC scheme is proposed for coupled STL tasks offering a desired trade-off between the systems' performance and the computational complexity of previously proposed centralized approaches. The proposed scheme is solved in discrete-time yet continuous-time constraint satisfaction is ensured thanks to an appropriate tightening of the constraint sets.
Finally, in part III we consider time-invariant objectives such as safety, formation and tracking of single and multiple agents, respectively, and propose a set of feedback control laws ensuring the satisfaction of the desired objectives at all times.