Stability analysis of ultrasonic bone cutting under dynamic loads

• The cutting stability is studied oriented to robotic ultrasonic bone surgery. • The destabilization mechanism of UBS in frequency tracking mode is revealed. • A load stability model of UBS is established. • The critical dynamic load in cutting process is predicted. The ultrasonic bone scalpel (UBS) is widely used in surgical procedures due to its unique advantage of safety. A principal operational challenge is that the UBS lacks stability during the cutting process, often affecting the surgical quality. This paper proposes a novel cutting stability analysis method for the UBS and reveals its destabilization mechanism under dynamic load variations. We combine the control strategy of under the resonant frequency tracking (RFT) with the impedance characteristics of the UBS to construct a load stability model, which can solve the frequency response under dynamic load variations and predict the critical load for destabilization. In addition, the dynamic load carrying capacity of the UBS is tested experimentally to verify the validity of the proposed model. Compared to previous load carrying performance analysis methods for ultrasonic structures, the dynamic load stability analysis in this paper is closer to practical applications. This work complements the theory of ultrasonic cutting and is expected to promote the application of robotic bone cutting in surgery.