Using optical tracking for kinematic testing of medical robots.

BACKGROUND: In image-guided robotic interventions, an error component is related to the positioning error of the manipulator. Therefore, measuring the kinematic error is required during robot development. However, no specialized measurement device exists for this task. This study explores the possibility of using optical tracking for robot measurement.

METHODS: A CNC machine is used to position an optical marker, generating a gold standard reference. Repeated position measurements are acquired with an NDI Polaris Hybrid® optical tracker at each static location, and averaged. These measurements are compared to the reference set.

RESULTS: Averaging repeated static position measurements improves precision (200-500 samples). Measurement accuracy ranges between 44 μm and 137 μm in close proximity of the tracker.

CONCLUSIONS: Repeated static position measurements in the near field of view enable the optical tracker to outperform its general-purpose accuracy specification. Optical tracking may be used to test robot kinematics with a high degree of accuracy.