Fast Feedback Control over Multi-hop Wireless Networks with Mode Changes\n and Stability Guarantees

Abstract

Closing feedback loops fast and over long distances is key to emerging\ncyber-physical applications; for example, robot motion control and swarm\ncoordination require update intervals of tens of milliseconds. Low-power\nwireless communication technology is preferred for its low cost, small form\nfactor, and flexibility, especially if the devices support multi-hop\ncommunication. Thus far, however, feedback control over multi-hop low-power\nwireless networks has only been demonstrated for update intervals on the order\nof seconds. To fill this gap, this paper presents a wireless embedded system\nthat supports dynamic mode changes and tames imperfections impairing control\nperformance (e.g., jitter and message loss), and a control design that exploits\nthe essential properties of this system to provably guarantee closed-loop\nstability for physical processes with linear time-invariant dynamics in the\npresence of mode changes. Using experiments on a cyber-physical testbed with 20\nwireless devices and multiple cart-pole systems, we are the first to\ndemonstrate and evaluate feedback control and coordination with mode changes\nover multi-hop networks for update intervals of 20 to 50 milliseconds.\n