The detection of drill bit break-through for the enhancement of safety in mechatronic assisted orthopaedic drilling

The present surgical drilling processes, which are performed manually, can greatly benefit from mechatronic assistance. Measurement of bone drilling f orce can contribute significantly towards the enhancement of safety through the detection of drill bit breakthrough in order to prevent excessive prot rusion of the drill bit. This paper describes a reliable and repeatable met hod of break-through detection based on a modified Kalman filter when drill ing into long bones. A control strategy for the break-through detection is also provided. By applying the modified Kalman filter to force difference b etween successive samples (FDSS), the imminent drill bit break-through can be detected using different threshold levels of Kalman filtered FDSS (K-FDS S) in the presence of system compliance and inherent drilling force fluctua tion. In addition, the method of break-through detection can be applied to different drill bit types over a range of drilling conditions. (C) 1999 Els evier Science Ltd. All rights reserved.