Control Communication Co-Design for Wide Area Cyber-Physical Systems

Abstract

Wide Area Cyber-Physical Systems (WA-CPSs) are a class of control systems that integrate low-powered sensors, heterogeneous actuators, and computer controllers into large infrastructure that span multi-kilometre distances. Current wireless communication technologies are incapable of meeting the communication requirements of range and bounded delays needed for the control of WA-CPSs. To solve this problem, we use a Control Communication Co-design approach for WA-CPSs, that we refer to as the C 3 approach, to design a novel Low-Power Wide Area (LPWA) MAC protocol called Ctrl-MAC and its associated event-triggered controller that can guarantee the closed-loop stability of a WA-CPS. This is the first article to show that LPWA wireless communication technologies can support the control of WA-CPSs. LPWA technologies are designed to support one-way communication for monitoring and are not appropriate for control. We present this work using an example of a water distribution network application, which we evaluate both through a co-simulator (modeling both physical and cyber subsystems) and testbed deployments. Our evaluation demonstrates full control stability, with up to 50% better packet delivery ratios and 80% less average end-to-end delays when compared to a state-of-the-art LPWA technology. We also evaluate our scheme against an idealised, wired, centralised, control architecture, and show that the controller maintains stability and the overshoots remain within bounds.

Scaling beyond Bandwidth Limitations: Wireless Control with Stability Guarantees under Overload

“…We also note a few other recent control-communication co-designs that use STC [30,31] or ETC [9,55] to reduce communication and that have been evaluated on real wireless networks. In contrast to our work, these co-designs target slow physical systems (e.g., water distribution networks [9,55]) requiring update intervals on the order of seconds and have only been evaluated on simulated physical systems. Most importantly, none of them addresses the overload problem.…”

“…3) the size of all packets increases, which reduces the network bandwidth available for the control messages. In our experiments, this reduces M C to 2 control messages per round with an aggregate overhead of S = 5 B (see (9)). Further, we use a threshold of P δ = 0.5 and choose êmax = (0.03, 0.03, 0.1, 0.3) as the maximum error to derive the priorities (cf.…”

“…The relationships are a bit more complex in our predictive approach, because M C and the duration of a slot in Mixer are interrelated. The slot_time term in (26) additionally depends on the aggregate overhead S as calculated in (9). This requires M C to be calculated iteratively by choosing a value for M C , then calculating S, and inally checking if this is below the maximum communication time.…”

An overview on low energy wake-up radio technology: Active and passive circuits associated with MAC and routing protocols

“…Later on, we suggest an unusual LPWA MAC protocol, Ctrl-MAC proposed by L. Bhatia et al [149], which stabilizes the control demands of wide area cyber-physical systems accompanied by the communication restrictions and forced by Low-Power Wide Area (LPWA) communication technologies. Furthermore, the co-simulation test consequences prove that LoRaWAN and LoRaWAN++ technologies can not afford data reception warranties to the control system.…”

Scaling Beyond Bandwidth Limitations: Wireless Control With Stability Guarantees Under Overload

“…We also note a few other recent control-communication co-designs that use STC [28] or ETC [9,49] to reduce communication and that have been evaluated on real wireless networks. In contrast to our work, these co-designs target slow physical systems (e.g., water distribution networks [9,49]) requiring update intervals on the order of seconds and have only been evaluated on simulated physical systems. Most importantly, none of them addresses the overload problem.…”