Random access policies for wireless networked control systems with energy harvesting sensors

Abstract

In this paper, we study wireless networked control systems in which the sensing devices are powered by energy harvesting. We consider a scenario with multiple plants, where the sensors communicate their measurements to their respective controllers over a shared wireless channel. Due to the shared nature of the medium, sensors transmitting simultaneously can lead to packet collisions. In order to deal with this, we propose the use of random access communication policies and, to this end, we translate the control performance requirements to successful packet reception probabilities. The optimal scheduling decision is to transmit with a certain probability, which is adaptive to plant, channel and battery conditions. Moreover, we provide a stochastic dual method to compute the optimal scheduling solution, which is decoupled across sensors, with only some of the dual variables needed to be shared between nodes. Furthermore, we also consider asynchronicity in the values of the variables across sensor nodes and provide theoretical guarantees on the stability of the control systems under the proposed random access mechanism. Finally, we provide extensive numerical results that corroborate our claims.

Stability of Control Systems with Feedback from Energy Harvesting Sensors

“…In particular, [11]- [13] have studied controllers which guarantee closed-loop stability under conservative assumptions. While these do not directly assume that the open-loop system is stable, they indirectly assume that at every time increment in the process, enough energy arrives so that the sensor can communicate reliably enough with the plant to guarantee uniform decay in a norm of the system's plant state.…”