Virtual-Fixture Based Drilling Control for Robot-Assisted Craniotomy: Learning From Demonstration

One of the promising solutions for drilling craniotomy is robot-assisted surgery with human guidance. The present study deals with a piecewise collaborative drilling task assisted by a robot while containing aligning and drilling. It can enable surgeons to complete the operation more efficiently and accurately. The switched virtual fixture (VF) between drilling and aligning can be addressed using intention recognition, which learns from demonstrating human-guided force during the collaborative drilling. The training of the switching condition is derived in terms of Gaussian mixture models (GMMs) and the intention recognition is achieved using the Kullback-Leibler (KL) divergence between the GMMs and human-guided real-time sampled forces. To evaluate the performance of aligning and drilling, two experiments are conducted corresponding to the steps of drilling tasks. The compliance, accuracy, and costing time are demonstrated in the experiments. The results indicate that the proposed method has better performance (0.78 $\pm$ 0.50 mm in collaborative drilling tasks for positioning accuracy and 38.65 $\pm$ 5.00 s for time-consuming) than the conventional method(2.96 $\pm$ 1.90 mm for positioning accuracy and 55.41 $\pm$ 13.70 s for time-consuming).

I. Introduction

The craniotomy is an essential neurosurgical process for removing a part of the patient's skull and is a safe and valid method to manage patients with brain tumors or chronic subdural hematoma [1]. Through image-guided surgery, surgeons could localize the lesion precisely. After that, they could accurately determine the optimal trajectory [2], and the target points as well as drilling points of craniotomy. By this procedure, the surgical tool can access a specific intracranial area under medical image guidance. In most cases of craniotomies, the surgeon should use a surgical tool to drill burr holes on the skull [3] which is time-consuming, dangerous, and laborious. During this procedure, the surgeon should hold the heavy (around 1 kg) drilling instrument with vibration and maintain a precise positioning control to avoid accidents. In this way of drilling, the surgeon's strength and concentration are drastically consumed. To finish the craniotomy and the follow-up operation (such as brain tumor removal), two experienced surgeons are required. Alternatively, with the help of the robot, one surgeon can conduct a whole craniotomy and the follow-up operation.