Evaluation of Pseudo-Haptic Interactions with Soft Objects in Virtual Environments

This paper proposes a pseudo-haptic feedback method conveying simulated soft surface stiffness information through a visual interface. The method exploits a combination of two feedback techniques, namely visual feedback of soft surface deformation and control of the indenter avatar speed, to convey stiffness information of a simulated surface of a soft object in virtual environments. The proposed method was effective in distinguishing different sizes of virtual hard nodules integrated into the simulated soft bodies. To further improve the interactive experience, the approach was extended creating a multi-point pseudo-haptic feedback system. A comparison with regards to (a) nodule detection sensitivity and (b) elapsed time as performance indicators in hard nodule detection experiments to a tablet computer incorporating vibration feedback was conducted. The multi-point pseudo-haptic interaction is shown to be more time-efficient than the single-point pseudo-haptic interaction. It is noted that multi-point pseudo-haptic feedback performs similarly well when compared to a vibration-based feedback method based on both performance measures elapsed time and nodule detection sensitivity. This proves that the proposed method can be used to convey detailed haptic information for virtual environmental tasks, even subtle ones, using either a computer mouse or a pressure sensitive device as an input device. This pseudo-haptic feedback method provides an opportunity for low-cost simulation of objects with soft surfaces and hard inclusions, as, for example, occurring in ever more realistic video games with increasing emphasis on interaction with the physical environment and minimally invasive surgery in the form of soft tissue organs with embedded cancer nodules. Hence, the method can be used in many low-budget applications where haptic sensation is required, such as surgeon training or video games, either using desktop computers or portable devices, showing reasonably high fidelity in conveying stiffness perception to the user

Evaluation of Pseudo-Haptic Interactions with Soft Objects in Virtual Environments

This paper proposes a pseudo-haptic feedback method conveying simulated soft surface stiffness information through a visual interface. The method exploits a combination of two feedback techniques, namely visual feedback of soft surface deformation and control of the indenter avatar speed, to convey stiffness information of a simulated surface of a soft object in virtual environments. The proposed method was effective in distinguishing different sizes of virtual hard nodules integrated into the simulated soft bodies. To further improve the interactive experience, the approach was extended creating a multi-point pseudo-haptic feedback system. A comparison with regards to (a) nodule detection sensitivity and (b) elapsed time as performance indicators in hard nodule detection experiments to a tablet computer incorporating vibration feedback was conducted. The multi-point pseudo-haptic interaction is shown to be more time-efficient than the single-point pseudo-haptic interaction. It is noted that multi-point pseudo-haptic feedback performs similarly well when compared to a vibration-based feedback method based on both performance measures elapsed time and nodule detection sensitivity. This proves that the proposed method can be used to convey detailed haptic information for virtual environmental tasks, even subtle ones, using either a computer mouse or a pressure sensitive device as an input device. This pseudo-haptic feedback method provides an opportunity for low-cost simulation of objects with soft surfaces and hard inclusions, as, for example, occurring in ever more realistic video games with increasing emphasis on interaction with the physical environment and minimally invasive surgery in the form of soft tissue organs with embedded cancer nodules. Hence, the method can be used in many low-budget applications where haptic sensation is required, such as surgeon training or video games, either using desktop computers or portable devices, showing reasonably high fidelity in conveying stiffness perception to the user

Nodule detection sensitivities with Wilson score intervals at a 95% confidence level of vibration feedback, single-point pseudo-haptic feedback, and multi-point pseudo-haptic feedback.

<p>Nodule detection sensitivities with Wilson score intervals at a 95% confidence level of vibration feedback, single-point pseudo-haptic feedback, and multi-point pseudo-haptic feedback.</p

Concept of interactive haptic display using tablet computers.

<p>Concept of interactive haptic display using tablet computers.</p

Single-point and multi-point soft surface stiffness simulation.

<p>(a) A single indenter avatar represents one interaction point; (b) the locations of the three indenter avatars (marked using blue, red, and yellow dots), barycenter of the triangle (marked using a black dot), and the affected soft surface nodes of each indenter avatar (marked using small blue, red, and yellow circles).</p

Schematic diagram of the pseudo-haptic surface stiffness simulation using a desktop computer.

<p>Schematic diagram of the pseudo-haptic surface stiffness simulation using a desktop computer.</p

Time used for nodule detection using visual feedback of surface deformation, speed control strategy, and combination of the two feedbacks.

<p>Time used for nodule detection using visual feedback of surface deformation, speed control strategy, and combination of the two feedbacks.</p

The nodule detection sensitivity, specificity and accuracies with Wilson score intervals at a 95% confidence level of visual feedback of surface deformation, speed modification strategy, and combination of the two feedbacks.

<p>The nodule detection sensitivity, specificity and accuracies with Wilson score intervals at a 95% confidence level of visual feedback of surface deformation, speed modification strategy, and combination of the two feedbacks.</p

Comparison experiment of pseudo-haptic feedback techniques.

<p>(a) The stiffness distribution information used in our experiment; the surface is divided into left and right parts; four types of status (A1, B1, C1 and no hard inclusion buried inside) are possible at each side; thirteen status combinations at the two sides are considered, and (b) the user interfaces of the three feedback modalities.</p

Comparison of sensitivity and accuracy.

<p>Comparison of sensitivity and accuracy.</p