Virtual reality training and assessment in laparoscopic rectum surgery

Background: Virtual-reality (VR) based simulation techniques offer an efficient and low cost alternative to conventional surgery training. This article describes a VR training and assessment system in laparoscopic rectum surgery. Methods: To give a realistic visual performance of interaction between membrane tissue and surgery tools, a generalized cylinder based collision detection and a multi-layer mass-spring model are presented. A dynamic assessment model is also designed for hierarchy training evaluation. Results: With this simulator, trainees can operate on the virtual rectum with both visual and haptic sensation feedback simultaneously. The system also offers surgeons instructions in real time when improper manipulation happens. The simulator has been tested and evaluated by ten subjects. Conclusions: This prototype system has been verified by colorectal surgeons through a pilot study. They believe the visual performance and the tactile feedback are realistic. It exhibits the potential to effectively improve the surgical skills of trainee surgeons and significantly shorten their learning curve. © 2014 John Wiley & Sons, Ltd

A novel haptic model and environment for maxillofacial surgical operation planning and manipulation

This paper presents a practical method and a new haptic model to support manipulations of bones and their segments during the planning of a surgical operation in a virtual environment using a haptic interface. To perform an effective dental surgery it is important to have all the operation related information of the patient available beforehand in order to plan the operation and avoid any complications. A haptic interface with a virtual and accurate patient model to support the planning of bone cuts is therefore critical, useful and necessary for the surgeons. The system proposed uses DICOM images taken from a digital tomography scanner and creates a mesh model of the filtered skull, from which the jaw bone can be isolated for further use. A novel solution for cutting the bones has been developed and it uses the haptic tool to determine and define the bone-cutting plane in the bone, and this new approach creates three new meshes of the original model. Using this approach the computational power is optimized and a real time feedback can be achieved during all bone manipulations. During the movement of the mesh cutting, a novel friction profile is predefined in the haptical system to simulate the force feedback feel of different densities in the bone

Expanding Haptic Workspace for Coupled-Object Manipulation

Haptic force-feedback offers a valuable cue in exploration and manipulation of virtual environments. However, grounding of many commercial kinesthetic haptic devices limits the workspace accessible using a purely position-control scheme. The bubble technique has been recently presented as a method for expanding the user’s haptic workspace. The bubble technique is a hybrid position-rate control system in which a volume, or “bubble,” is defined entirely within the physical workspace of the haptic device. When the device’s end effector is within this bubble, interaction is through position control. When exiting this volume, an elastic restoring force is rendered, and a rate is applied that moves the virtual accessible workspace. Existing work on the bubble technique focuses on point-based touching tasks. When the bubble technique is applied to simulations where the user is grasping virtual objects with part-part collision detection, unforeseen interaction problems surface. This paper discusses three details of the user experience of coupled-object manipulation with the bubble technique. A few preliminary methods of addressing these interaction challenges are introduced

A Conceptual Framework to Support Natural Interaction for Virtual Assembly Tasks

Over the years, various approaches have been investigated to support natural human interaction with CAD models in an immersive virtual environment. The motivation for this avenue of research stems from the desire to provide a method where users can manipulate and assemble digital product models as if they were manipulating actual models. The ultimate goal is to produce an immersive environment where design and manufacturing decisions which involve human interaction can be made using only digital CAD models, thus avoiding the need to create costly preproduction physical prototypes. This paper presents a framework to approach the development of virtual assembly applications. The framework is based on a Two Phase model where the assembly task is divided into a free movement phase and a fine positioning phase. Each phase can be implemented using independent techniques; however, the algorithms needed to interface between the two techniques are critical to the success of the method. The paper presents a summary of three virtual assembly techniques and places them within the framework of the Two Phase model. Finally, the conclusions call for the continued development of a testbed to compare virtual assembly methods

Interacting With Grasped Objects in Expanded Haptic Workspaces Using the Bubble Technique

Haptic force-feedback can provide useful cues to users of virtual environments. Body-based haptic devices are portable but the more commonly used ground-based devices have workspaces that are limited by their physical grounding to a single base position and their operation as purely position-control devices. The “bubble technique” has recently been presented as one method of expanding a user\u27s haptic workspace. The bubble technique is a hybrid position-rate control system in which a volume, or “bubble,” is defined entirely within the physical workspace of the haptic device. When the device\u27s end effector is within this bubble, interaction is through position control. When the end effector moves outside this volume, an elastic restoring force is rendered, and a rate is applied that moves the virtual accessible workspace. Publications have described the use of the bubble technique for point-based touching tasks. However, when this technique is applied to simulations where the user is grasping virtual objects with part-to-part collision detection, unforeseen interaction problems surface. Methods of addressing these challenges are introduced, along with discussion of their implementation and an informal investigation