BACKGROUND Training surgeons to use surgical robots are becoming part of surgical training curricula. We propose a novel method of training fine-motor skills such as Microscopic Selection Task (MST) for robot-assisted surgery using virtual reality (VR) with objective quantification of performance. We also introduce vibrotactile feedback (VTFB) to study its impact on training performance. METHODS We use a VR-based environment to perform MST with varying degrees of difficulties. Using a well-known human-computer interaction paradigm and incorporating VTFB, we quantify the performance: speed, precision and accuracy. RESULTS MST with VTFB showed statistically significant improvement in performance metrics leading to faster completion of MST with higher precision and accuracy compared to that without VTFB. DISCUSSION The addition of VTFB to VR-based training for robot-assisted surgeries may improve performance outcomes in real robotic surgery. VTFB, along with proposed performance metrics, can be used in training curricula for robot-assisted surgeries.

Novel virtual reality based training system for fine motor skills: Towards developing a robotic surgery training system.

Latency is detrimental to haptic systems, specifically in networked telepresence systems. Although the latency effect on stiffness is well studied in the literature, it is not very clear if the latency effects on the stiffness perception are due to the displacement perception or the force perception. In this study, we propose passive probing which involves force perception alone, without any displacement of the finger, for studying latency effects. A psychophysical experiment is conducted with a set of artificially induced latencies which provides a quantitative measure of the effect of these latencies on three parameters: Just Noticeable Difference (JND), the time taken to reach the reference forces and the maximum overshoot. The results showed that the latency has a significant effect on the user ability in task performance after 185.5 ms. From the observation, the latency effect on JND in passive probing is similar to that of the stiffness perception (active probing) task which shows that the effect is significantly higher on the force perception rather than on the displacement perception.

Passive Probing Perception: Effect of Latency in Visual-Haptic Feedback

Abstract Consistent visual and haptic feedback is an important way to improve the user experience when interacting with virtual objects. However, the perception provided in Augmented Reality (AR) mainly comes from visual cues and amorphous tactile feedback. This work explores how to simulate positional vibrotactile feedback (PVF) with multiple vibration motors when colliding with virtual objects in AR. By attaching spatially distributed vibration motors on a physical haptic proxy, users can obtain an augmented collision experience with positional vibration sensations from the contact point with virtual objects. We first developed a prototype system and conducted a user study to optimize the design parameters. Then we investigated the effect of PVF on user performance and experience in a virtual and real object alignment task in the AR environment. We found that this approach could significantly reduce the alignment offset between virtual and physical objects with tolerable task completion time increments. With the PVF cue, participants obtained a more comprehensive perception of the offset direction, more useful information, and a more authentic AR experience.

HapticProxy: Providing Positional Vibrotactile Feedback on a Physical Proxy for Virtual-Real Interaction in Augmented Reality

Do we see rendered surface materials differently in virtual reality? A psychophysics-based investigation

Considering 3D interactions in Virtual-Reality (VR), it is critical to study how visual awareness of real hands influences users scaled interaction performance in different VR environments. We used...

Effect of Visual Awareness of the Real Hand on User Performance in Partially Immersive Virtual Environments: Presence of Virtual Kinesthetic Conflict

Haptic feedback in immersive virtual reality (IVR) systems is critical to enable a more intuitive and natural way of interacting with virtual objects. IVR-based haptic medical simulations such as needle insertion procedures have the potential to enhance clinicians’ haptic expertise. This work is a preliminary study on the use and implementation of IVR for needle simulators. Although few studies have quantified haptic skills such as force Just Noticeable Difference (JND) with the single finger, none have measured the force JND as recommended in the standard needle insertion protocol in an IVR environment. The hypothesis of this study is that there will be an improvement of force perception in the IVR, compared to that of the non-immersive virtual reality (NIVR) which facilitates the use of IVR for medical simulations. This paper emphasized on two objectives: firstly, the development of the observer state model for both the IVR and NIVR and the theoretical analysis of the psychophysical measures in both of the environments. Secondly, measures of force JND with the three fingers and comparison of these measures in NIVR to that of the IVR using psychophysical study with the force matching task, constant stimuli method, and isometric force probing stimuli to validate the model. Twenty voluntary subjects performed the experiment in both of the environments. Mean force JND and standard deviation of the JND were found to be 9.12% and 3.75% in the NIVR and 5.91% and 3.65% in the IVR (p value < 0.0001) which are in the same range of JNDs found in the literature (5–10%) for the NIVR using a single finger. Surprisingly, the results showed a better force JND in the IVR compared to that of the NIVR. Also, a simple state observer model was proposed to explain the improvement of force JND in the IVR. This study would quantitatively reinforce the use of IVR for the design of various medical simulators.

Improved force JND in immersive virtual reality needle insertion simulation

The haptic illusion based force feedback, known as pseudo-haptics, is used to simulate haptic explorations, such as stiffness, without using a force feedback device. There are many computer mouse based pseudo-haptics work reported in the literature. However, none has explored the mechanics of the pseudohaptics. The objective of this paper is to derive an analytical relation between the displacement of the mouse to that of a virtual spring assuming equal work done in both cases (mouse and virtual spring displacement) and experimentally validate their relation. A psychophysical experiment was conducted on eight subjects to discriminate the stiffness of two virtual springs using 2 Alternative Force Choice (AFC) discrimination task, Constant Stimuli method to measure Just Noticeable Difference (JND) for pseudo-stiffness. The mean pseudo-stiffness JND and average Weber fraction were calculated to be 14% and 9.54% respectively. The resulting JND and the Weber fraction from the experiment were comparable to that of the psychophysical parameters in the literature. Currently, this study simulates the haptic illusion for 1 DOF, however, it can be extended to 6 DOF.

Ravali Gourishetti

Papers

Passive Probing Perception: Effect of Latency in Visual-Haptic Feedback

Improved force JND in immersive virtual reality needle insertion simulation

Mechanics of pseudo-haptics with computer mouse