Feedback Control Goes Wireless: Guaranteed Stability over Low-power Multi-hop Networks
This work enables fast feedback control over low-power wireless multi-hop networks for applications like robot motion control and swarm coordination, which previously required update intervals on the order of seconds.
The paper presents a wireless embedded system and control design that achieves closed-loop stability for linear time-invariant dynamics over low-power multi-hop networks with update intervals of 20-50 milliseconds, demonstrated on a 20-node testbed with cart-pole systems.
Closing feedback loops fast and over long distances is key to emerging applications; for example, robot motion control and swarm coordination require update intervals of tens of milliseconds. Low-power wireless technology is preferred for its low cost, small form factor, and flexibility, especially if the devices support multi-hop communication. So far, however, feedback control over wireless multi-hop networks has only been shown for update intervals on the order of seconds. This paper presents a wireless embedded system that 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 closed-loop stability for physical processes with linear time-invariant dynamics. Using experiments on a cyber-physical testbed with 20 wireless nodes and multiple cart-pole systems, we are the first to demonstrate and evaluate feedback control and coordination over wireless multi-hop networks for update intervals of 20 to 50 milliseconds.