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Surgeons in various medical areas (orthopedic surgery, neurosurgery, dentistry etc.) are using motor-driven drilling tools
to make perforations in hard tissues (bone, enamel, dentine, cementum etc.) When the penetration requires very precise
angles and accurate alignment with respect to different targets, precision cannot be obtained by using visual estimation
and hand-held tools. Robots have been designed to allow for very accurate relative positioning of the patient and the
surgical tools, and in certain classes of applications the location of bone target and inclination of the surgical tool can be
accurately specified with respect to an inertial frame of reference. However, patient positioning errors as well as position
changes during surgery can jeopardize the precision of the operation, and drilling parameters have to be dynamically
adjusted. In this paper the authors present a quantitative method to evaluate the corrected position and inclination of the
drilling tool, to account for translational and rotational errors in displaced target position. The compensation algorithm
applies principles of inverse kinematics wherein a faulty axis in space caused by the translational and rotational errors of
the target position is identified with an imaginary true axis in space by enforcing identity through a modified trajectory.
In the absence of any specific application, this algorithm is verified on Solid Works, a commercial CAD tool and found
to be correct. An example problem given at the end vindicates this statement.
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