Packet priority assignment for wireless control systems of multiple physical systems Abstract   Wireless control systems (WCSs) have gained much attention lately, due to their easy deployment and flexibility compared to wired control systems. However, this comes at the cost of possibly increased network delay and packet losses, that can significantly impact the control system performance, and possibly its stability. Such problems become even more relevant if the network is shared among different control systems, and thus becomes a scarce resource, like in Industrial Internet of Things applications.  In this paper, we aim at minimizing the performance degradation of the WCS with multiple physical systems sharing a network. We propose a dynamic packet scheduling solution to minimize the performance error of WCS, by dynamically determining the packet priorities of different control systems and characteristic of network paths. We consider two cases for network path selection: (1) network delay only by developing a worstcase endtoend delay analysis; (2) network delay  reliability by proposing a new network quality model including both delay and packet losses, both of which are very important for the quality of output of the WCSs. Our solution is evaluated over two different use cases to show the generality of the approach: the WCS for a set of inverted pendula, and the WCS for small modular reactors in a nuclear power plant. The results show that the proposed approach allows for a more stable performance even in presence of highly nonlinear systems, sensitive to timevarying delays, as well as in presence of high network interference.

Embedded systems for timexe2x80x93critical applications over WiFi: design and experimental assessment Networked embedded systems for industrial control based on wireless support provide several advantages over wired counterparts, but often reveal unsuitable for the most demanding industrial control applications, such as advanced manufacturing and cooperative robotics. Data exchange over IEEE 802.11 networks may theoretically represent an appropriate solution for timexe2x80x93critical applications, provided that unreliability and nonxe2x80x93 determinism issues are properly handled. In this respect, this paper hence proposes an original solution, based on a crossxe2x80x93 layer approach, to allow the realization of highxe2x80x93speed industrial controlxe2x80x93overxe2x80x93WiFi networked embedded systems. The proposal implements a novel robust framexe2x80x93delay state estimator, a time efficient communication policy, and a specific tuning of critical protocol parameters. Suitable hardwarexe2x80x93inxe2x80x93thexe2x80x93loop experiments have been carried out implemented exploiting two different embedded systems. Preliminary results show that the proposed architecture enables industrial control applications requiring a sampling rate of up to 1 kHz, even in presence of non negligible communication errors.