FollowMe! : distributed movement coordination in wireless sensor and actuator networks

Bosch, Stephan (2008) FollowMe! : distributed movement coordination in wireless sensor and actuator networks.

Abstract:In this thesis, we explore the potential of WSAN technology in dynamic applications requiring a senseand- react control loop by considering the problem of distributed movement coordination of vehicles on wheels. The final goal is to obtain a self-organizing group (or swarm) of mobile nodes that maintain a formation by periodically exchanging sensed movement information. Such a coordinated team of mobile wireless sensor and actuator nodes can bring numerous benefits for various applications in the field of cooperative surveillance, mapping unknown areas, disaster management, automated highway and space exploration. The work we present in this thesis is considers a pair of vehicles that synchronize their movements, thus trying to maintain a specific formation. We use toy cars as prototype vehicles for this research. One of the two cars acts as the leader, being remotely controlled by the user, and the other one represents the follower, which implements a control loop for mimicking the leader’s movements. Each vehicle has a low-power wireless sensor node attached, featuring a 3D accelerometer and a magnetic compass. Velocity and heading are computed on both vehicles in real time using inertial navigation techniques. The leader periodically transmits its measurements to the follower, which implements a lightweight fuzzy logic controller for imitating the leader’s movement pattern. This solution is not restricted to vehicles on wheels, but could support any moving entities capable of determining their velocity and heading. We call our initial implementation FollowMe. We report in detail on all development phases, covering design, simulation, implementation and testing. We perform the tests on our university’s running track and hockey field. The simulations and tests show that the system exhibits the desired leader-follower behavior, using just the compact, low-cost wireless sensors and actuators. Making use of a fuzzy controller facilitates the implementation on resource constrained sensor nodes and handles robustly the noisy sensor data as well as the rough mechanical capabilities of the vehicles. The vehicle simulations we devised show adequately realistic results and provide a means to test, evaluate, tune and debug the controller. However, some issues are still of concern, such as the effect of inclination changes on the sensor readings, the accumulating errors seen in the velocity estimate, the sensitivity of the compass sensor to external influence and the stability and the overall performance of the follower controller. Also, the simulations are open for improvement towards more realistic physical models of the vehicles
Item Type:Essay (Master)
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:54 computer science
Programme:Computer Science MSc (60300)
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