Abstract-In this paper, we combine inertial sensing and sensor network technology to create a pedestrian dead reckoning system. The core of the system is a lightweight sensor-and-wireless-embedded device called NavMote that is carried by a pedestrian. The NavMote gathers information about pedestrian motion from an integrated magnetic compass and accelerometers. When the NavMote comes within range of a sensor network (composed of NetMotes), it downloads the compressed data to the network. The network relays the data via a RelayMote to an information center where the data are processed into an estimate of the pedestrian trajectory based on a dead reckoning algorithm. System details including the NavMote hardware/software, sensor network middleware services, and the dead reckoning algorithm are provided. In particular, simple but effective step detection and step length estimation methods are implemented in order to reduce computation, memory, and communication requirements on the Motes. Static and dynamic calibrations of the compass data are crucial to compensate the heading errors. The dead reckoning performance is further enhanced by wireless telemetry and map matching. Extensive testing results show that satisfactory tracking performance with relatively long operational time is achieved. The paper also serves as a brief survey on pedestrian navigation systems, sensors, and techniques.Index Terms-Dead reckoning, pedestrian navigation system, wireless sensor network.

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Altstmct-The purpose of this paper is to develop methods to reduce the complexity of nonlinear distributed systems by using symmetry propers within the system. A method for contracting and expanding controllable nonlinear systems is developed which maintains the controllability of the original system. In fact, it is shown that an entire equivalence class of symmetric nonlinear distributed control systems can be determined by checking the controllability of only one of its members. A group of mobile robots is used to demonstrate the utility of methods presented.

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