MRI-Compatible Brain Puncture Robot With Variable RCM: Design and Accuracy Assessment

Background: MRI-guided neurosurgery requires high-precision puncture, but is challenged by magnetic field constraints and brain tissue deformation. Methods: The mechanism is constructed from non-magnetic materials (e.g., PEEK and ceramic bearings) and driven by ultrasonic piezoelectric actuators to ensure safety in strong magnetic fields. A composite swing–arc RCM design extends the RCM workspace to a hemispherical region, enabling dynamic adjustment within a 220 mm diameter. D–H parameters are refined through multimodal calibration, and RCM stability is experimentally validated. Results: After calibration, the end-effector absolute error is 2.16 mm with a repeatability of ± 1.02 mm, and the mean RCM deviation is 0.57 mm. Conclusions: The system supports autonomous puncture under real-time MRI, covers the cranial workspace and provides a precise, flexible solution for neurosurgical procedures.