We introduce the problem of computing robot motion strategies that maintain visibility of a moving target in a cluttered workspace. Both motion constraints (as considered in standard motion planning) and visibility constraints (as considered in visual tracking) must be satisfied. Additional criteria, such as the total distance traveled, can be optimized. The general problem is divided into two categories, on the basis of whether the target is predictable. For the predictable case, an algorithm that computes optimal, numerical solutions is presented. For the more challenging case of a partially-predictable target, two online algorithms are presented that each attempt to maintain future visibility with limited prediction. One strategy maximizes the probability that the target will remain in view in a subsequent time step, and the other maximizes the minimum time in which the target could escape the visibility region. We additionally discuss issues resulting from our implementation and experiments on a mobile robot system.

It is important to set landmarks when a robot needs to navigate in a certain environment and to measure its own location; however, it has not been discussed well how to arrange landmarks in the optimal way until now. We, therefore, demonstrate the possibility of design of the optimal arrangement of artificial landmarks. First, we make it clear the optimization problem with regard to the arrangement of landmarks. Second, as one example of the artificial landmarks, we introduce a signboard system. Third, we propose a methodology to evaluate arrangement of landmarks assuming an obstacled rectangular environment. Fourth, we apply the algorithm of spatial competition to the optimal arrangement of landmarks. Finally, simulation results indicate that even though our method is not global optimization approach we can obtain closely optimal and practical arrangement with the minimum number of landmarks which satisfies the necessary condition.