Consider a mobile robot tasked with localizing targets at unknown locations by obtaining relative measurements. The observations can be bearing or range measurements. How should the robot move so as to localize the targets and minimize the uncertainty in their locations as quickly as possible? Most existing approaches are either greedy in nature or rely on accurate initial estimates.We formulate this path planning problem as an unsupervised learning problem where the measurements are aggregated using a Bayesian histogram filter. The robot learns to minimize the total uncertainty of each target in the shortest amount of time using the current measurement and an aggregate representation of the current belief state. We analyze our method in a series of experiments where we show that our method outperforms a standard greedy approach. In addition, its performance is also comparable to an offline algorithm which has access to the true location of the targets.
We study the problem of generating control laws for systems with unknown dynamics. Our approach is to represent the controller and the value function with neural networks, and to train them using loss functions adapted from the Hamilton-Jacobi-Bellman (HJB) equations. In the absence of a known dynamics model, our method first learns the state transitions from data collected by interacting with the system in an offline process. The learned transition function is then integrated to the HJB equations and used to forward simulate the control signals produced by our controller in a feedback loop.In contrast to trajectory optimization methods that optimize the controller for a single initial state, our controller can generate near-optimal control signals for initial states from a large portion of the state space. Compared to recent modelbased reinforcement learning algorithms, we show that our method is more sample efficient and trains faster by an order of magnitude. We demonstrate our method in a number of tasks, including the control of a quadrotor with 12 state variables.
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