Node localization using mobile robots in delay-tolerant sensor networks

We present a novel scheme for node localization in a Delay-Tolerant Sensor Network (DTN). In a DTN, sensor devices are often organized in network clusters that may be mutually disconnected. Some mobile robots may be used to collect data from the network clusters. The key idea in our scheme is to use this robot to perform location estimation for the sensor nodes it passes based on the signal strength of the radio messages received from them. Thus, we eliminate the processing constraints of static sensor nodes and the need for static reference beacons. Our mathematical contribution is the use of a Robust Extended Kalman Filter (REKF)-based state estimator to solve the localization. Compared to the standard extended Kalman filter, REKF is computationally efficient and also more robust. Finally, we have implemented our localization scheme on a hybrid sensor network test bed and show that it can achieve node localization accuracy within 1m in a large indoor setting.

Secure localization with attack detection in wireless sensor networks

Rapid technological advances have enabled the development of low-cost sensor networks for various monitoring tasks, where it is important to estimate the positions of a number of regular sensor nodes whose locations cannot be known apriori. We address the problem of localizing the regular nodes with range-based location references obtained from certain anchor nodes referred to as beacons, particularly in an adverse environment where some of the beacons may be compromised. We propose an innovative modular solution featuring two lightweight modules that are for dedicated functionalities, respectively, but can also be closely integrated. First, we harness simple geometric triangular rules and an efficient voting technique to enable the attack detection module, which identifies and filters out malicious location references. We then develop a secure localization module that computes and clusters certain reference points, and the position of the concerned regular node is estimated with the centroid of the most valuable reference points identified. Extensive simulations show that our attack detection module can detect compromised beacons effectively, and the secure localization module can subsequently provide a dependable localization service in terms of bounded estimation error. The integrated system turns out to be tolerant of malicious attacks even in highly challenging scenarios.

RSSI-based localization of a wireless sensor node with a flying robot

We consider the problem of navigating a ying robot to a specific sensor node within a wireless sensor network. This target sensor node periodically sends out beacons. The robot is capable of sensing the received signal strength of each received beacon (RSSI measurements). Existing approaches for solving the sensor spotting problem with RSSI measurements do not deal with noisy channel conditions and/or heavily depend on additional hardware capabilities. In this work we reduce RSSI uctuations due to noise by continuously sampling RSSI values and maintaining an exponential moving average (EMA). The EMA values enable us to detect significant decrease of the received signal strength. In this case it is reasoned that the robot is moving away from the sensor. We present two basic variants to decide a new moving direction when the robot moves away from the sensor. Our simulations show that our approaches outperform competing algorithms in terms of success rate and ight time. Infield experiments with real hardware, a ying robocopter successfully and quickly landed near a sensor placed in an outdoor test environment. Traces show robustness to additional environmental factors not accounted for in our simulations.

The Museum of Doubt

Is there a God? Does my bum look big in this? Why doesn’t my house cost only the materials used to build it? Is Video Art dead? When Peter Hill curated his first Museum of Doubt exhibition at Zeppelin Projects in Brunswick, these were some of the questions his artist friends wrote on one wall of the gallery. Those artists included Jon Cattapan, Phil Edwards, Julian Goddard, Ceri Hahn, and Peter Ellis. Others, who are also in this second outing of The Museum of Doubt, include Louise Weaver, Patrick Pound, Josh Foley and Michael Vale. How do we know what is true or false in any given visual statement? How willing are we to suspend our disbelief? And does that even matter if the artworks can be enjoyed for their own formal beauty, angst, or inquisitiveness?“I have a great sympathy with both doubt and faith as beacons for navigating this sublime universe,” says Peter Hill. “Remembering that the sublime in art, as in life and death, hovers between beauty and terror. Doubt and faith are both on the same side of the same coin – a coin that has “certainty” on the reverse. Most of the problems we face today are caused by individuals and nations being “certain” that they have the answer. Don’t listen to them. Be skeptical. The truth can be approached, as Karl Popper, the great philosopher of science tells us, but it can rarely be found. It can only be falsified.”So bring your doubt and your faith to this Wunderkammer of Super Fictions and enjoy the lightness, the darkness, and the strangeness in the works of: Glen Clarke, Josh Foley, Tony Garifalakis, Grant Hill, Peter Hill, Patrick Pound, Michael Vale, Louise Weaver and Robert Zhao.