Registration of a robotic system to a medical imaging system

The presence of robots not only in industrial settings but also in operating rooms is increasing with advancements in technology. They are not only huge machines carrying out tedious and arduous tasks while being caged behind fences, but also work in collaboration, close proximity of, and in cooperation with humans. Image guided minimally invasive approaches to accurately navigate a robot to precise anatomical locations can be followed only once the robot is registered to the medical imaging system. In this paper, we present an approach to register a robotic system to a medical imaging system without the use of any tracking device or continuous X-ray imaging. The system consists of a lightweight robot equipped with internal torque sensors. The registration is realized by a series of landmark transformations. The robot is manually moved and guided to distinct landmarks whose positions are known in the coordinate system of the imaging system. By driving the robot to these distinct landmarks, their position relative to the coordinate system of the robotic system is also known. By comparing the respective positions of the landmarks in the two coordinate systems, both systems are registered. With 8 screws on the operating table used as landmarks for this registration, we obtain a median error of [6.9, 20.6, 18.6] mm and a standard deviation of [2.9, 2.6, 2.2] mm when compared to an X-ray based ground truth.