Payal Patel

Bio: Payal Patel is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Psychophysics & Illusion. The author has an hindex of 1, co-authored 2 publications receiving 4 citations.

Power Law Based “Out of Body” Tactile Funneling for Mobile Haptics

Abstract: ‘‘Out of body” tactile illusions can serve as a tool to exploit the limitations of human perception to augment the information displayed in the mobile haptic devices. The objective of this study was to establish a psychophysics based mathematical relationship between the intensity of physical and phantom stimulus rendered “out of the body.” In order to achieve this objective, three experiments were conducted, the first experiment was to compare three existing algorithms (linear, logarithmic, and square) defined for “on the body” when extended to “out of the body,” the second experiment was to test the pertinence of the best performing algorithm from first experiment, and the third experiment was designed to identify an ideal mathematical relation using psychophysical studies. Fifteen subjects participated in the experiments and the physical stimuli were provided to the index fingers of both the hands such that the phantom stimulus was perceived in the mid-air between them. Results of the first experiment depicted that the “square algorithm” was the best among the three. Results of the second experiment proved “square algorithm” to be better than other two algorithms but not ideal to define mathematical relation for “out of body” tactile funneling illusion. Results of the third experiment established a novel and better performing algorithm using “power relationship” between the intensity of physical and phantom stimulus leading to “out of body” tactile funneling. Although this paper defines the power relationship between the phantom and physical stimulus intensity, the relationship between location of phantom stimulus and the physical stimulus intensity remains the future scope of this study.

Sinusoidal Vibration Source Localization in Two-Dimensional Space Around the Hand

Abstract: There are use cases where presenting spatial information via the tactile sense is useful (e.g., situations where visual and audio senses are not available). Conventional methods that directly attach a vibrotactile array to a user's body present spatial information such as direction by having users localize the vibration source from among the sources in the array. These methods suffer from problems such as heat generation of the actuator or the installation cost of the actuators in a limited space. A promising method of coping with these problems is to place the vibrotactile array at a distance from the body, instead of directly attaching it to the body, with the aim of presenting spatial information in the same way as the conventional method. The present study investigates the method's effectiveness by means of a psychophysical experiment. Specifically, we presented users with sinusoidal vibrations from remote vibrotactile arrays in the space around the hand and asked them to localize the source of the vibration. We conducted an experiment to investigate the localization ability by using two vibration frequencies (30 Hz as a low frequency and 230 Hz as a high frequency). We chose these two frequencies since they effectively activate two distinctive vibrotactile channels: the rapidly adapting afferent channel and the Pacinian channel. The experimental results showed that humans can recognize the direction of the vibration source, but not the distance, regardless of the source frequency. The accuracy of the direction recognition varied slightly according to the vibration source direction, and also according to the vibration frequency. This suggests that the calibration of stimulus direction is required in the case of both high and low frequencies for presenting direction accurately as intended. In addition, the accuracy variance of direction recognition increased as the source became farther away, and the degree of increase was especially large with the low-frequency source. This suggests that a high frequency is recommended for presenting accurate direction with low variance.

Reduction of Electrotactile Perception Threshold Using Background Thermal Stimulation.

Abstract: Electrotactile displays reproduce tactile properties of an object such as texture and shape to provide feedback in human-machine interactions. Electrotactile perception threshold (EPT) is a critical psychophysical parameter in designing a safe display as prolonged usage causes skin irritation. This study's main objective was to reduce EPT with background thermal stimulation (BTS) and analyze the qualitative and quantitative aspects of EPT with and without BTS. A psychophysical experiment was conducted to measure EPT with and without BTS (+7 °C)) over a wide range of stimulus frequencies of EPT from 20 Hz to 640 Hz. Findings from these experiments showed a reduction in the EPT (∆EPT), which was 13% to 17% (with an average of 15%). Reduced EPT may provide safer and comfortable electrotactile displays for prolonged usage.

Haptic Actuation Plate for Multi-Layered In-Vehicle Control Panel

Abstract: High-fidelity localized feedback has the potential of providing new and unique levels of interaction with a given device. Achieving this in a cost-effective reproducible manner has been a challenge in modern technology. Past experiments have shown that by using the principles of constructive wave interference introduced by time offsets it is possible to achieve a position of increased vibration displacement at any given location. As new interface form factors increasingly incorporate curved surfaces, we now show that these same techniques can successfully be applied and mechanically coupled with a universal actuation plate.

Extended phantom sensation: vibrotactile-based movement sensation in the area outside the inter-stimulus

Abstract: Vibrotactile phantom sensation is an intuitive methodology for perceiving the localization of a moving object. However, the presentation area is limited to the inter-stimulus. To extend the range o...