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We consider the problem of selecting an optimal set of sensors to estimate the states of linear dynamical systems. Specifically, the goal is to choose (at design-time) a subset of sensors (satisfying certain budget constraints) from a given set in order to minimize the trace of the steady state a priori or a posteriori error covariance produced by a Kalman filter. We show that the a priori and a posteriori error covariance-based sensor selection problems are both NP-hard, even under the additional assumption that the system is stable. We then provide bounds on the worst-case performance of sensor selection algorithms based on the system dynamics, and show that greedy algorithms are optimal for a certain class of systems. However, as a negative result, we show that certain typical objective functions are not submodular or supermodular in general. While this makes it difficult to evaluate the performance of greedy algorithms for sensor selection (outside of certain special cases), we show via simulations that these greedy algorithms perform well in practice. [ABSTRACT FROM AUTHOR]

We consider a scenario where mobile agents are required to collect measurements from a geographically dispersed set of sensors and return them to a base. An agent faces a risk of destruction while traversing the environment to reach the sensors, and gets a reward for gathering a sensor measurement only if it successfully returns to base. We first consider the single agent scenario and characterize several properties of the optimal policy for the agent based on a quantity that we term the "reward-to-risk" ratio of the tasks. We provide the optimal policy when the risk of destruction is sufficiently high, and then extend our analysis to multiple (heterogeneous) agents, with potentially different costs and survival probabilities. In particular, when the risk of destruction is sufficiently high, we show that the multi-agent task allocation problem has a submodular structure, and accordingly provide a greedy algorithm that is guaranteed to return an allocation that is within a 1 2 factor of optimal. [ABSTRACT FROM AUTHOR]