Abstract: The main source of space mapping error in the minimally invasive surgical robot
navigation system is analyzed. Four types of the space mapping error are described in detail.
Through the simulation analysis it is concluded that the benchmark positioning error and the target
mapping error is proportional, and the target mapping error is relatively small when the
benchmark positioning error range in two dimensions is small. Using simulation analysis to
influence the distribution way of marked points space mapping precision based on affine
coordinate, two kinds of marked point distribution modes which strongly affects space mapping
precision are obtained as the coplanar distribution and the marked point distribution in which the
target cannot be surrounded in the distribution scope. Coplanar distribution can lead to aberration
when solving mapping matrix by using affine coordinate system and can result in mapping error
distortion mutations. When targets are out of the surrounding areas of marked points, the target
mapping error will be greater than space mapping when targets are in the surrounding areas of
marked points.

Key words: medical robot, navigation system, space mapping, accuracy analysis, simulation