Given the rise in surgeries performed with surgical robots and associated robotics research efforts, tool tracking methods have the potential to provide quantitative feedback concerning surgical performance and establish absolute tool tracking to help advance surgical robotics research. We have created a platform-agnostic method for low-cost tracking of surgical tool shafts in Cartesian space in near real time. We employ a joint Hough Transform - Geometric Constraint approach to locate the tool tips in the stereo camera channels independently. Cartesian coordinates are registered using a custom polynomial depth - disparity model. The algorithm was developed using a low-cost experimental webcam setup and evaluated using a da Vinci surgical endoscope. The algorithm was benchmarked for 3D tracking accuracy and computational speed. The system can locate the tool tip in 3D space with an average accuracy of 3.05 mm at 25.86 frames per second using the webcam setup. For the endoscope setup this algorithm has an average tracking accuracy of 8.68 mm in 3D and 1.88 mm in 2D with an average frame rate of 26.9 FPS. The algorithm also demonstrated successful tracking of tools using captured video from a real surgical procedure.

We propose a new computation model for simulating elastic thin shells at interactive rates. Existing graphical simulation methods are mostly based on dihedral angle energy functions, which need to compute the first order and second order partial derivatives with respect to current vertex positions as bending forces and stiffness matrices. The symbolic derivatives are complicated in nonisometric element deformations. To simplify computing the derivatives, instead of directly constructing the dihedral angle energy, we use the orientation change energy of mesh edges. A continuum-mechanics-based orientation-preserving rod element model is developed to provide the bending forces. The advantage of our method is simple bending force and stiffness matrix computation, since in the rod model, we apply a novel incremental construction of the deformation gradient tensor to linearize both tensile and orientation deformations. Consequently, our model is efficient, easy to implement, and supports both quadrilateral and triangle meshes. It also treats shells and plates uniformly.

In this paper, we introduce a novel application of volume modeling techniques on laser Benign Prostatic Hyperplasia (BPH) therapy simulation. The core technique in our system is an algorithm for simulating the tissue vaporization process by laser heating. Different from classical volume CSG operations, our technique takes experimental data as the guidance to determine the vaporization amount so that only a specified amount of tissue is vaporized in each time. Our algorithm uses a predictor-corrector strategy. First, we apply the classical CSG algorithm on a tetrahedral grid based distance field to estimate the vaporized tissue amount. Then, a volume-correction phase is applied on the distance field. To improve the performance, we further propose optimization approaches for efficient implementation.