Penetration detection method for bone cutting tool in craniotomy procedures
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Insinööritieteiden korkeakoulu |
Master's thesis
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Authors
Date
2017-05-08
Department
Major/Subject
Mechanical Engineering
Mcode
IA3027
Degree programme
Konetekniikan koulutusohjelma
Language
en
Pages
60 + 8
Series
Abstract
Craniotomy is a common neurosurgical procedure in which the skull is opened to allow the surgeon access to the brain. The skull bone is to be cut without damaging underlying delicate tissues. A powered cutting instrument is used to cut the skull bone. In conventional methods, sometimes the safety of underlying tissues is compromised while cutting the skull bone. A new method of controlling the cutting tool penetration is introduced, which is based on vibrational analysis of the cutting process. Typically, amplitudes of vibrations are very sensitive to small changes in cutting parameters and this makes it difficult to rely on vibrational analysis methods in control systems. Alternatively, a method introduced in this work which relies on existence of a very specific frequency component, called corresponding frequency, in the frequency spectrum. The corresponding frequency is a function of known parameters such as rotational speed and number of the cutting edges of the cutting tool. The existence of this specific frequency component indicates that the tool tip has not penetrated under the skull bone. However, when this frequency component vanishes the control system realizes that the penetration depth of the cutting tool shall be reduced to eliminate the excessive penetration under the skull. The cutting vibrations for different cutting tool designs are measured. The FFT analysis results are studied and utilized for comparing the cutting tools. Based on the results cutting tools are categorized as cutters or vibrators. The design of the best cutter and vibrator tools are combined to design a new type of cutting tool, called hybrid tool. The hybrid tool is a cutting tool design that is optimized to work with the introduced method of cutting tool penetration detection.Description
Supervisor
Kuosmanen, PetriThesis advisor
Kuosmanen, PetriKeywords
penetration detection, breakthrough detection, bone cutting, robotic surgery, vibration analysis