Physics-Based Haptic Simulation of Bone Machining

Abstract

We present a physics-based training simulator for bone machining. Based on experimental studies, the energy required to remove a unit volume of bone is a constant for every particular bone material. We use this physical principle to obtain the forces required to remove bone material with a milling tool rotating at high speed. The rotating blades of the tool are modeled as a set of small cutting elements. The force of interaction between a cutting element and bone is calculated from the energy required to remove a bone chip with an estimated thickness and known material stiffness. The total force acting on the cutter at a particular instant is obtained by integrating the differential forces over all cutting elements engaged. A voxel representation is used to represent the virtual bone and removed chips for calculating forces of machining. We use voxels that carry bone material properties to represent the volumetric haptic body and to apply underlying physical changes during machining. Experimental results of machining samples of a real bone confirm the force model. A real-time haptic implementation of the method in a dental training simulator is described.

A mechanistic force model for simulating haptics of hand-held bone burring operations

“…Arbabtafti et al [7][8][9] developed a physics based model for haptic simulation of bone machining. The physical principle behind the model is that the energy required to remove a unit volume of bone is a constant for a particular bone material.…”

Real-time collision detection for long thin medical instruments in virtual reality-based simulators

“…al. They applied mechanical principles of metal machining to a voxel-based haptic interaction in a bone milling virtual environment [4]. They integrated into the force model the effect of spindle speed, feed rate of the tool and bone stiffness.…”

“…However, the surface-based models present some disadvantages, such as [3]: cannot represent complex objects interior or heterogeneous volumes, not suitable for simulation of cutting through different tissues and cannot model fluid flow or bone fracturing. In contrast, volumetric models (voxel-based models) are suitable for hard-tissue removal due to the fact that enable the implementation of volume structural changes and material heterogeneous properties [4]. The voxel-based representations can be easily created from Computer Tomography (CT) and Magnetic Resonance Imaging (MRI) scans.…”

Making robots mill bone more like human surgeons: Using bone density and anatomic information to mill safely and efficiently

“…In the field of otologic surgery, Williamson et al used the correlation between drilling force and bone density to predict the pose of a robot-controlled drill based on density estimates from the pre-operative images and real-time force measurements [16]. Additionally, forces in otologic bone milling have been modeled in the development of a physics-based haptic simulator [17]. The voxelized model developed in [17] is used in the present work to adjust the cutting tool orientation and velocity along the trajectory for autonomous temporal bone milling such that the forces are decreased when the tool is in close proximity to vital anatomy and the tool is oriented for improved cutting efficiency.…”