Lindsay O. Long

Salient haptic skills trainer: initial validation of a novel simulator for training force-based laparoscopic surgical skills.

BackgroundThere is an increasing need for efficient training simulators to teach advanced laparoscopic skills beyond those imparted by a box trainer. In particular, force-based or haptic skills must be addressed in simulators, especially because a large percentage of surgical errors are caused by the over-application of force. In this work, the efficacy of a novel, salient haptic skills simulator is tested as a training tool for force-based laparoscopic skills.MethodsThirty novices with no previous laparoscopic experience trained on the simulator using a pre-test–feedback–post-test experiment model. Ten participants were randomly assigned to each of the three salient haptic skills—grasping, probing, and sweeping—on the simulator. Performance was assessed by comparing force performance metrics before and after training on the simulator.ResultsData analysis indicated that absolute error decreased significantly for all three salient skills after training. Participants also generally decreased applied forces after training, especially at lower force levels. Overall, standard deviations also decreased after training, suggesting that participants improved their variability of applied forces.ConclusionsThe novel, salient haptic skills simulator improved the precision and accuracy of participants when applying forces with the simulator. These results suggest that the simulator may be a viable tool for laparoscopic force skill training. However, further work must be undertaken to establish full validity. Nevertheless, this work presents important results toward addressing simulator-based force-skills training specifically and surgical skills training in general.

Objective Differentiation of Force-Based Laparoscopic Skills Using a Novel Haptic Simulator

BACKGROUND There is a growing need for effective surgical simulators to train the novice resident with a core skill set that can be later used in advanced operating room training. The most common simulator-based laparoscopic skills curriculum, the Fundamentals of Laparoscopic Skills (FLS), has been demonstrated to effectively teach basic surgical skills; however, a key deficiency in current surgical simulators is lack of validated training for force-based or haptic skills. In this study, a novel haptic simulator was examined for construct validity by determining its ability to differentiate between the force skills of surgeons and novices. METHODS A total of 34 participants enrolled in the study and were divided into two groups: novices, with no previous surgical experience and surgeons, with some level of surgical experience (including upper level residents and attendings). All participants performed a force-based task using grasping, probing, or sweeping motions with laparoscopic tools on the simulator. In the first session, participants were given 3 trials to learn specific forces associated with locations on a graphic; after this, they were asked to reproduce forces at each of the locations in random order. A force-based metric (score) was used to record performance. RESULTS On probing and grasping tasks, novices applied significantly greater overall forces than surgeons. When analyzed by force levels, novices applied greater forces on the probing task at lower and mid-range forces, for grasping at low-range forces ranges and, for sweeping at high-range forces. CONCLUSIONS The haptic simulator successfully differentiated between novice and surgeon force skill level at specific ranges for all 3 salient haptic tasks, establishing initial construct validity of the haptic simulator. Based on these results, force-based simulator metrics may be used to objectively measure haptic skill level and potentially train residents. Haptic simulator development should focus on the 3 salient haptic skills (grasping, probing, and sweeping) where precise force application is necessary for successful task outcomes.

Effects of calibration to visual and haptic feedback on near-field depth perception in an immersive virtual environment

Distances are regularly underestimated in immersive virtual environments (IVEs) [Witmer and Kline 1998; Loomis and Knapp 2003]. Few experiments, however, have examined the ability of calibration to overcome distortions of depth perception in IVEs. This experiment is designed to examine the effect of calibration via haptic and visual feedback on distance estimates in an IVE. Participants provided verbal and physical reach responses to target distances presented during three sessions; a baseline measure without feedback, a calibration session with visual and haptic feedback, and finally a post-calibration session without feedback. Feedback was shown to calibrate distance estimates within an IVE. Discussion focused on the possibility that costly solutions and research endeavors seeking to remedy the compression of distances may become less necessary if users are simply given the opportunity to use manual activity to calibrate to the IVE.

Visual spatial abilities in uninhabited ground vehicle task performance during teleoperation and direct line of sight

Two experiments investigated the role of spatial abilities on uninhabited ground vehicle (UGV) performance under two different viewing conditions: direct line of sight and teleoperation. The ability to operate a mobile robot was indexed by task completion time and total number of course collisions. Results showed that participants with higher spatial abilities exhibited superior performance in both direct line of sight and teleoperation. Performance under direct line of sight was correlated with both spatial relations and spatial visualization, whereas performance during teleoperation was only correlated with spatial relations ability. Understanding the roles of spatial abilities under different viewing conditions will aid in the advancement of selection criteria and training paradigms for robot operators.

Haptic Perception of Distance-To-Break for Compliant Tissues in a Surgical Simulator

In minimally invasive surgery (MIS), it is critical to have the ability to accurately interpret haptic information and apply appropriate force magnitudes onto soft tissue in order to minimize tissue trauma. The surgeon’s administration of force onto tissue reveals useful perceptual information which guides further haptic interaction making the force perception in MIS a dynamic process. It has been hypothesized that the compliant nature of soft tissue during force application provides biomechanical information denoting tissue failure. Specifically, the relationship between applied force and material deformation rate specifies the distance remaining until the tissue will fail, which is termed distance-to-break (DTB). Two experiments explored sensitivity to DTB; one with an exploratory task and the other using a unidirectional task. Findings revealed that observers could reliably perceive DTB in simulated biological tissues in the exploratory task but they were unable to perform the unidirectional task. It was also found that the perception of DTB can be improved through feedback training. Implications for optimizing training in MIS simulators are discussed.

Simulator-Based Assessment of Haptic Surgical Skill A Comparative Study

The aim of this study was to examine if the forces applied by users of a haptic simulator could be used to distinguish expert surgeons from novices. Seven surgeons with significant operating room expertise and 9 novices with no surgical experience participated in this study. The experimental task comprised exploring 4 virtual materials with the haptic device and learning the precise forces required to compress the materials to various depths. The virtual materials differed in their stiffness and force-displacement profiles. The results revealed that for nonlinear virtual materials, surgeons applied significantly greater magnitudes of force than novices. Furthermore, for the softer nonlinear and linear materials, surgeons were significantly more accurate in reproducing forces than novices. The results of this study suggest that the magnitudes of force measured using haptic simulators may be used to objectively differentiate experts’ haptic skill from that of novices. This knowledge can inform the design of virtual reality surgical simulators and lead to the future incorporation of haptic skills training in medical school curricula.

An evaluation of immersive viewing on spatial knowledge acquisition in spherical panoramic environments

Abstract We report the results of an experiment conducted to examine the effects of immersive viewing on a common spatial knowledge acquisition task of spatial updating task in a spherical panoramic environment (SPE). A spherical panoramic environment, such as Google Street View, is an environment that is comprised of spherical images captured at regular intervals in a real world setting augmented with virtual navigational aids such as paths, dynamic maps, and textual annotations. Participants navigated the National Mall area of Washington, DC, in Google Street View in one of two viewing conditions; desktop monitor or a head-mounted display with a head orientation tracker. In an exploration phase, participants were first asked to navigate and observe landmarks on a pre-specified path. Then, in a testing phase, participants were asked to travel the same path and to rotate their view in order to look in the direction of the perceived landmarks at certain waypoints. The angular difference between participants’ gaze directions and the landmark directions was recorded. We found no significant difference between the immersive and desktop viewing conditions on participants’ accuracy of direction to landmarks as well as no difference in their sense of presence scores. However, based on responses to a post-experiment questionnaire, participants in both conditions tended to use a cognitive or procedural technique to inform direction to landmarks. Taken together, these findings suggest that in both conditions where participants experience travel based on teleportation between waypoints, the visual cues available in the SPE, such as street signs, buildings and trees, seem to have a stronger influence in determining the directions to landmarks than the egocentric cues such as first-person perspective and natural head-coupled motion experienced in the immersive viewing condition.

Surgeon’s Perception of Soft Tissue Constraints and Distance-to-Break in a Simulated Minimally Invasive Surgery Task

Accurately perceiving biomechanical properties of tissues is imperative for minimizing tissue trauma and preventable injuries in minimally invasive surgery (MIS). Research has demonstrated that novice observers are able to perceive and use the higher-order mechanical information in compliant, deformable materials which denotes the point at which the material will fail, or break, known as Distance -to-Break (DTB). The present study explored the effect of experience on the perception of DTB. Specifically, this study investigated whether surgeons are able to perceive and utilize DTB in compliant tissue materials more precisely than novices. Using a simulated probing task, results demonstrated that surgeons were more sensitive to DTB, were more accurate at estimating the point at which materials would fail, and were more accurate at applying force onto materials without breaking them. Findings underscore the importance of haptic invariants such as DTB in surgical tasks and the efficacy of using simulators to train haptic skills.

Augmented Interaction: Applying the Principles of Augmented Cognition to Human-Technology and Human-Human Interactions

The field of Augmented Cognition (AugCog) has evolved over the past decade from its origins in the Defense Advanced Research Projects Agency (DARPA)-funded research program, emphasizing modulation of closed-loop human-computer interactions within operational environments, to address a broader scope of domains, contexts, and science and technology (S&T) challenges. Among these are challenges related to the underlying theoretical and empirical research questions, as well as the application of advances in the field within contexts such as training and education. This paper summarizes a series of ongoing research and development (R&D) efforts aimed at applying an AugCog-inspired framework to enhance both human-technology and human-human interactions within a variety of training and operational domains.

Investigating the Relationship between Visual Spatial Abilities and Robot Operation during Direct Line of Sight and Teleoperation

Objective: To determine how scores on standard spatial measures correlate with the ability to operate a robot under different teleoperation conditions. Background: Past work has demonstrated that there is a relationship between visual spatial ability and teleoperation performance. Method: In this experiment participants completed a spatial visualization (VZ-2) and spatial relation (S-2) measure, and teleoperated a robot through both low and high difficulty courses under direct line of sight (DLS) and teleoperation (TO) conditions. Performance was determined by course completion time and the total number of collisions made during navigation. Results and Conclusion: Aggregate visual spatial ability was inversely correlated with operator performance under each of the experimental conditions. Analyzed independently, only spatial relations ability correlated with TO performance, while both measures correlated with DLS operation. Application: Better understanding of the relationship between spatial abilities and teleoperation performance can assist in the selection and training of future operators, as well as the design of superior interfaces.