Safety Controller Synthesis for Stochastic Networked Systems under Communication Constraints

TL;DR

This paper presents a method for designing safety controllers for stochastic networked systems with communication delays and data loss, ensuring safety with probabilistic guarantees.

Contribution

It introduces an augmented stochastic system model and uses control barrier certificates to synthesize controllers under communication constraints.

Findings

Successfully guarantees safety with probabilistic bounds.

Validates approach on an RLC circuit example.

Translates safety constraints into matrix inequalities.

Abstract

This paper develops a framework for synthesizing safety controllers for discrete-time stochastic linear control systems (dt-SLS) operating under communication imperfections. The control unit is remote and communicates with the sensor and actuator through an imperfect wireless network. We consider a constant delay in the sensor-to-controller channel (uplink), and data loss in both sensor-to-controller and controller-to-actuator (downlink) channels. In our proposed scheme, data loss in each channel is modeled as an independent Bernoulli-distributed random process. To systematically handle the uplink delay, we first introduce an augmented discrete-time stochastic linear system (dt-ASLS) by concatenating all states and control inputs that sufficiently represent the state-input evolution of the original dt-SLS under the delay and packet loss constraints. We then leverage control barrier certificates for dt-ASLS to synthesize a controller that ensures the stochastic safety of dt-SLS, guaranteeing that all trajectories remain outside unsafe regions with a quantified probabilistic bound. Our approach translates safety constraints into matrix inequalities, leading to an optimization problem that eventually quantifies the probability of satisfying the safety specification in the presence of communication imperfections. We validate our results on an RLC circuit subject to both constant delay and probabilistic data loss.