UTCS CPS

Introduction

Applying wireless technologies in control systems can significantly enhance the system mobility and reduce the deployment and maintenance cost. Existing wireless technology standards, however either cannot provide real-time guarantee on packet delivery or are not fast enough to support high-speed control systems which typically require 1kHz or higher sampling rate. Nondeterministic packet transmission and insufficiently high sampling rate will severely hurt the control performance. To address this problem, in this project, we design and implement a real-time high-speed wireless communication protocol called RT-WiFi. RT-WiFi is a TDMA data link layer protocol based on IEEE 802.11 physical layer to provide deterministic timing guarantee on packet delivery and high sampling rate. It incorporates configurable components for adjusting design trade-offs including sampling rate, latency variance, reliability, and compatibility to existing Wi-Fi networks, thus can serve as an ideal communication platform for supporting a wide range of high-speed wireless control systems. We developed RT-WiFi on commercial off-the-shelf hardware and applied it into wireless network control systems.

Publication

Conference:

  • "Robust Time Delay Compensation in a Wireless Motion Control System with Double Disturbance Observers",
    Wenlong Zhang, Masayoshi Tomizuka, Yi-Hung Wei, Quan Leng, Song Han, and Aloysius K. Mok,
    accepted and to appear in the American Control Conference (ACC), 2015.
  • "Improving Control Performance by Minimizing Jitter in RT-WiFi Networks",
    Quan Leng, Yi-Hung Wei, Song Han, Aloysius K. Mok, Wenlong Zhang, Masayoshi Tomizuka,
    IEEE Real-Time Systems Symposium (RTSS), 2014.
  • "Time Delay Compensation in a Wireless Tracking Control System with Previewed Reference",
    Wenlong Zhang, Masayoshi Tomizuka, Yi-Hung Wei, Quan Leng, Song Han, Aloysius K. Mok,
    American Control Conference (ACC), 2014.
  • "RT-WiFi: Real-Time High-Speed Communication Protocol for Wireless Cyber-Physical Control Applications",
    Yi-Hung Wei, Quan Leng, Song Han, Aloysius K. Mok, Wenlong Zhang, Masayoshi Tomizuka,
    IEEE Real-Time Systems Symposium (RTSS), 2013.

    (Best Paper Award)

Workshop, Magazine, and Work-in-Progress:

  • "A High-speed, Real-time Mobile Gait Rehabilitation System",
    Wenlong Zhang, Yi-Hung Wei, Quan Leng and Song Han,
    ACM XRDS Magazine - Cyber-Physical Systems, Volume 20 Issue 3, Spring 2014, Pages 46-51. (Invited Article)
  • "Towards Building a High-speed Real-time Mobile Gait Rehabilitation System",
    Wenlong Zhang, Yi-Hung Wei, Quan Leng, Song Han, Masayoshi Tomizuka, Aloysius K. Mok,
    Smart America Challenge workshop, 2013.
  • "RT-WiFi: Real-Time High-Speed Communication Protocol for Wireless Control Systems",
    Yi-Hung Wei, Quan Leng, Song Han, Aloysius K. Mok, Wenlong Zhang, Masayoshi Tomizuka, Tianji Li, David Malone, Douglas J. Leith,
    ACM SIGBED Review 10(2): 28, 2013.

Code Release

RT-WiFi v0.1

RT-WiFi driver v0.1. RT-WiFi driver is built on top of the ath9k driver in backports driver collection. This release v0.1 is based on backports driver v3.13.2. This version of RT-WiFi driver, we implement basic TDMA features with static TDMA link schedule based on our RTSS 2013 paper. Please go through the following user guide before you use this driver.

  • Code
  • Manual

    • Citation

    Please acknowledge the use of the code with a citation. 

            @inproceedings{rtwifi13,
          title={R{T}-{W}i{F}i: Real-time high-speed communication protocol for wireless cyber-physical control applications},
          author={Wei, Yi-Hung and Leng, Quan and Han, Song and Mok, Aloysius K and Zhang, Wenlong and Tomizuka, Masayoshi},
          booktitle={Real-Time Systems Symposium (RTSS), 2013 IEEE 34th},
          pages={140--149},
          year={2013},
          organization={IEEE}
        }