Figure 1.
Our motion planner computes actions (insertions and direction changes, indicated by dots) to steer the needle from an insertion entry region (vertical line on left between the solid squares) to the target (open circle) inside soft tissue, without touching critical areas indicated by polygonal obstacles in the imaging plane. The motion of the needle is not known with certainty; the needle tip may be deflected during insertion due to tissue inhomogeneities or other unpredictable soft tissue interactions. We explicitly consider this uncertainty to generate motion plans to maximize the probability of success, ps, the probability that the needle will reach the target without colliding with an obstacle or exiting the workspace boundary. Relative to a planner that minimizes path length, our planner considering uncertainty may generate longer paths with greater clearance from obstacles to maximize ps.