  Mobile manipulators have gained attention for the potential in performing
large-scale tasks which are beyond the reach of fixed-base manipulators. The
Robotic Task Sequencing Problem for mobile manipulators often requires
optimizing the motion sequence of the robot to visit multiple targets while
reducing the number of base placements. A two-step approach to this problem is
clustering the task-space into clusters of targets before sequencing the robot
motion. In this paper, we propose a task-space clustering method which
formulates the clustering step as a Set Cover Problem using bipartite graph and
reachability analysis, then solves it to obtain the minimum number of target
clusters with corresponding base placements. We demonstrated the practical
usage of our method in a mobile drilling experiment containing hundreds of
targets. Multiple simulations were conducted to benchmark the algorithm and
also showed that our proposed method found, in practical time, better solutions
than the existing state-of-the-art methods.
