Stabilization of systems with asynchronous sensors and controllers

We study the stabilization of networked control systems with asynchronous sensors and controllers. Offsets between the sensor and controller clocks are unknown and modeled as parametric uncertainty. First we consider multi-input linear systems and provide a sufficient condition for the existence of linear time-invariant controllers that are capable of stabilizing the closed-loop system for every clock offset in a given range of admissible values. For first-order systems, we next obtain the maximum length of the offset range for which the system can be stabilized by a single controller. Finally, this bound is compared with the offset bounds that would be allowed if we restricted our attention to static output feedback controllers.Comment: 32 pages, 6 figures. This paper was partially presented at the 2015 American Control Conference, July 1-3, 2015, the US

Desktop Magnetic Shielding System for the Calibration of High-Sensitivity Magnetometers

The objective of the study is a development of desk-top magnetic shielding system for the calibration of high-sensitive magnetometers, and the evaluation of their ability to produce a uniform magnetic field. This system consists of hexagonal tubes and a cylinder. The hexagonal tubes have a double-layered structure, an opening and an advantage in axial shielding performance. The cylinder has openings and an advantage in transverse shielding performance. A solenoid-like coil is wound around the hexagonal tubes to produce a uniform magnetic field. From the experimental results, the magnetic shielding and the calibration field properties are demonstrated. Within the half length of the system, the achieved total magnetic field (dc component) is less than 200 nT within ± 50 nT deviation, and the measured shielding factor is larger than 250. For producing a uniform magnetic field up to 10 kHz, we can use the 1/3 length of the system.ArticleIEEE TRANSACTIONS ON MAGNETICS. 47(10):4270-4273 (2011)journal articl