Bone Drilling Breakthrough Detection via Energy-Based Signal

In this paper, a novel energy-based signal, the removal energy density e_b, is proposed as the detecting signal to determine the breakthrough instances in bone drilling based on the energy approach during the process. The proposed signal is derived from the energy conversion and conservation in drilling process. And the relationship between the signal and the drilling parameter, e.g. drilling speed, feed rate and drill bit radius, is derived. Recursive least square with time forgetting factor is used to estimate e_b from the drilling parameters and drilling torque information. Unlike the traditional force profile, this proposed signal profile is similar under different drilling parameters including drilling speed and feed rate, hence reducing the difficulty in setting a threshold for the detection. Experiment on porcine bone is performed. The results show that the proposed signal profile is more consistent than the commonly used force profile, verifying the effectiveness of the proposed method.