Fast Feedback Control over Multihop Wireless Networks with Mode Changes and Stability Guarantees Closing feedback loops fast and over long distances is key to emerging cyberphysical applications; for example, robot motion control and swarm coordination require update intervals of tens of milliseconds. Lowpower wireless communication technology is preferred for its low cost, small form factor, and flexibility, especially if the devices support multihop communication. Thus far, however, feedback control over multihop lowpower wireless networks has only been demonstrated for update intervals on the order of seconds. To fill this gap, this paper presents a wireless embedded system that supports dynamic mode changes and tames imperfections impairing control performance (e.g., jitter and message loss), and a control design that exploits the essential properties of this system to provably guarantee closedloop stability for physical processes with linear timeinvariant dynamics in the presence of mode changes. Using experiments on a cyberphysical testbed with 20 wireless devices and multiple cartpole systems, we are the first to demonstrate and evaluate feedback control and coordination with mode changes over multihop networks for update intervals of 20 to 50 milliseconds.

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.