Real-time edge tracking using a tactile sensor

Object recognition through the use of input from multiple sensors is an important aspect of an autonomous manipulation system. In tactile object recognition, it is necessary to determine the location and orientation of object edges and surfaces. A controller is proposed that utilizes a tactile sensor in the feedback loop of a manipulator to track along edges. In the control system, the data from the tactile sensor is first processed to find edges. The parameters of these edges are then used to generate a control signal to a hybrid controller. Theory is presented for tactile edge detection and an edge tracking controller. In addition, experimental verification of the edge tracking controller is presented

A Review of Smart Materials in Tactile Actuators for Information Delivery

As the largest organ in the human body, the skin provides the important sensory channel for humans to receive external stimulations based on touch. By the information perceived through touch, people can feel and guess the properties of objects, like weight, temperature, textures, and motion, etc. In fact, those properties are nerve stimuli to our brain received by different kinds of receptors in the skin. Mechanical, electrical, and thermal stimuli can stimulate these receptors and cause different information to be conveyed through the nerves. Technologies for actuators to provide mechanical, electrical or thermal stimuli have been developed. These include static or vibrational actuation, electrostatic stimulation, focused ultrasound, and more. Smart materials, such as piezoelectric materials, carbon nanotubes, and shape memory alloys, play important roles in providing actuation for tactile sensation. This paper aims to review the background biological knowledge of human tactile sensing, to give an understanding of how we sense and interact with the world through the sense of touch, as well as the conventional and state-of-the-art technologies of tactile actuators for tactile feedback delivery

How a plantar pressure-based, tongue-placed tactile biofeedback modifies postural control mechanisms during quiet standing

The purpose of the present study was to determine the effects of a plantar pressure-based, tongue-placed tactile biofeedback on postural control mechanisms during quiet standing. To this aim, sixteen young healthy adults were asked to stand as immobile as possible with their eyes closed in two conditions of No-biofeedback and Biofeedback. Centre of foot pressure (CoP) displacements, recorded using a force platform, were used to compute the horizontal displacements of the vertical projection the centre of gravity (CoGh) and those of the difference between the CoP and the vertical projection of the CoG (CoP-CoGv). Altogether, the present findings suggest that the main way the plantar pressure-based, tongue-placed tactile biofeedback improves postural control during quiet standing is via both a reduction of the correction thresholds and an increased efficiency of the corrective mechanism involving the CoGh displacements

Engineering data compendium. Human perception and performance. User's guide

The concept underlying the Engineering Data Compendium was the product of a research and development program (Integrated Perceptual Information for Designers project) aimed at facilitating the application of basic research findings in human performance to the design and military crew systems. The principal objective was to develop a workable strategy for: (1) identifying and distilling information of potential value to system design from the existing research literature, and (2) presenting this technical information in a way that would aid its accessibility, interpretability, and applicability by systems designers. The present four volumes of the Engineering Data Compendium represent the first implementation of this strategy. This is the first volume, the User's Guide, containing a description of the program and instructions for its use

Tissue-conducted spatial sound fields

We describe experiments using multiple cranial transducers to achieve auditory spatial perceptual impressions via bone (BC) and tissue conduction (TC), bypassing the peripheral hearing apparatus. This could be useful in cases of peripheral hearing damage or where ear-occlusion is undesirable. Previous work (e.g. Stanley and Walker 2006, MacDonald and Letowski 2006)1,2 indicated robust lateralization is feasible via tissue conduction. We have utilized discrete signals, stereo and first order ambisonics to investigate control of externalization, range, direction in azimuth and elevation, movement and spaciousness. Early results indicate robust and coherent effects. Current technological implementations are presented and potential development paths discussed

The role of the ventral intraparietal area (VIP/pVIP) in parsing optic flow into visual motion caused by self-motion and visual motion produced by object-motion

Retinal image motion is a composite signal that contains information about two behaviourally significant factors: self-motion and the movement of environmental objects. It is thought that the brain separates the two relevant signals, and although multiple brain regions have been identified that respond selectively to the composite optic flow signal, which brain region(s) perform the parsing process remains unknown. Here, we present original evidence that the putative human ventral intraparietal area (pVIP), a region known to receive optic flow signals as well as independent self-motion signals from other sensory modalities, plays a critical role in the parsing process and acts to isolate object-motion. We localised pVIP using its multisensory response profile, and then tested its relative responses to simulated object-motion and self-motion stimuli; results indicated that responses were much stronger in pVIP to stimuli that specified object-motion. We report two further observations that will be significant for the future direction of research in this area; firstly, activation in pVIP was suppressed by distant stationary objects compared to the absence of objects or closer objects. Secondly, we describe several other brain regions that share with pVIP selectivity for visual object-motion over visual self-motion as well as a multisensory response

Adaptation to moving tactile stimuli and its effects on perceived speed and direction

Like other senses, tactile perception is subject to adaptation effects in which systematic changes in the pattern of sensory input lead to predictable changes in perception. In this thesis, aftereffects of adaptation to tactile motion are used to reveal the processes that give rise to tactile motion perception from the relevant sensory inputs. The first aftereffect is the tactile speed aftereffect (tSAE), in which the speed of motion appears slower following exposure to a moving surface. Perceived speed of a test surface was reduced by about 30% regardless of the direction of the adapting stimulus, indicating that the tSAE is not direction sensitive. Additionally, higher adapting speeds produced a stronger tSAE, and this dependence on adapting speed could not be attributed to differences in temporal frequency or spatial period that accompanied the different adapting speeds. The second motion aftereffect that was investigated is the dynamic tactile motion aftereffect (tMAE), in which a direction-neutral test stimulus appears to move in the opposite direction to previously felt adapting motion. The strength of the tMAE depended on the speed of the adapting motion, with higher speeds producing a stronger aftereffect. Both the tSAE and the tMAE showed evidence of an intensive speed code in their underlying neural populations, with faster adapting speeds resulting in stronger aftereffects. In neither case was any evidence of speed tuning found, that is, neither aftereffect was strongest with a match between the speeds of the adapting and test stimuli. This is compatible with the response properties of motion sensitive neurons in the primary somatosensory cortex. Despite these shared features, speed and direction are unlikely to be jointly coded in the same neurons because the lack of direction sensitivity of the tSAE requires neural adaptation effects to be uniform across neurons preferring all directions, whereas the tMAE requires direction selective adaptation

Adaptation to moving tactile stimuli and its effects on perceived speed and direction

Like other senses, tactile perception is subject to adaptation effects in which systematic changes in the pattern of sensory input lead to predictable changes in perception. In this thesis, aftereffects of adaptation to tactile motion are used to reveal the processes that give rise to tactile motion perception from the relevant sensory inputs. The first aftereffect is the tactile speed aftereffect (tSAE), in which the speed of motion appears slower following exposure to a moving surface. Perceived speed of a test surface was reduced by about 30% regardless of the direction of the adapting stimulus, indicating that the tSAE is not direction sensitive. Additionally, higher adapting speeds produced a stronger tSAE, and this dependence on adapting speed could not be attributed to differences in temporal frequency or spatial period that accompanied the different adapting speeds. The second motion aftereffect that was investigated is the dynamic tactile motion aftereffect (tMAE), in which a direction-neutral test stimulus appears to move in the opposite direction to previously felt adapting motion. The strength of the tMAE depended on the speed of the adapting motion, with higher speeds producing a stronger aftereffect. Both the tSAE and the tMAE showed evidence of an intensive speed code in their underlying neural populations, with faster adapting speeds resulting in stronger aftereffects. In neither case was any evidence of speed tuning found, that is, neither aftereffect was strongest with a match between the speeds of the adapting and test stimuli. This is compatible with the response properties of motion sensitive neurons in the primary somatosensory cortex. Despite these shared features, speed and direction are unlikely to be jointly coded in the same neurons because the lack of direction sensitivity of the tSAE requires neural adaptation effects to be uniform across neurons preferring all directions, whereas the tMAE requires direction selective adaptation