Perception Of Object Properties Research Articles

Recent Progress in Advanced Tactile Sensing Technologies for Soft Grippers

AbstractTactile sensing technology is crucial for soft grippers. Soft grippers equipped with intelligent tactile sensing systems based on various sensors can interact safely with the unstructured environments and obtain precise properties of objects (e.g., size and shape). It is essential to develop state‐of‐the‐art sensing technologies for soft grippers to handle different grasping tasks. In this review, the development of tactile sensing techniques for robotic hands is first introduced. Then, the principles and structures of different types of sensors normally adopted in soft grippers, including capacitive tactile sensors, piezoresistive tactile sensors, piezoelectric tactile sensors, fiber Bragg grating (FBG) sensors, vision‐based tactile sensors, triboelectric tactile sensors, and other advanced sensors developed recently are briefly presented. Furthermore, sensing modalities and methodologies for soft grippers are also described in aspects of force measurement, perception of object properties, slip detection, and fusion of perception. The application scenarios of soft grippers are also summarized based on these advanced sensing technologies. Finally, the challenges of tactile sensing technologies for soft grippers that need to be tackled are discussed and perspectives in addressing these challenges are pointed out.

How Heavy Is an Illusory Length?

The perception of object properties, such as size and weight, can be subject to illusions. Could a visual size illusion influence perceived weight? Here, we tested whether the size-weight illusion occurs when lifting two physically identical but perceptually different objects, by using an illusion of size. Participants judged the weight and length of 11 to 17 cm brass bars with equal density to which cardboard arrowheads were attached to create a Müller–Lyer illusion. We found that these stimuli induced an illusion in which the bar that was visually perceived as being shorter was also perceived as feeling heavier. In fact, a 5-mm increase in illusory length corresponded to a decrease in illusory weight of 15 g.

Expertise affects representation structure and categorical activation of grasp postures in climbing.

In indoor rock climbing, the perception of object properties and the adequate execution of grasping actions highly determine climbers' performance. In two consecutive experiments, effects of climbing expertise on the cognitive activation of grasping actions following the presentation of climbing holds was investigated. Experiment 1 evaluated the representation of climbing holds in the long-term memory of climbers and non-climbers with the help of a psychometric measurement method. Within a hierarchical splitting procedure subjects had to decide about the similarity of required grasping postures. For the group of climbers, representation structures corresponded clearly to four grip types. In the group of non-climbers, representation structures differed more strongly than in climbers and did not clearly refer to grip types. To learn about categorical knowledge activation in Experiment 2, a priming paradigm was applied. Images of hands in grasping postures were presented as targets and images of congruent, neutral, or incongruent climbing holds were used as primes. Only in climbers, reaction times were shorter and error rates were smaller for the congruent condition than for the incongruent condition. The neutral condition resulted in intermediate performance. The findings suggest that perception of climbing holds activates the commonly associated grasping postures in climbers but not in non-climbers. The findings of this study give evidence that the categorization of visually perceived objects is fundamentally influenced by the cognitive-motor potential for interaction, which depends on the observer's experience and expertise. Thus, motor expertise not only facilitates precise action perception, but also benefits the perception of action-relevant objects.

Infants' use of material properties to guide their actions with differently weighted objects

AbstractTwo studies with 9‐, 11‐ and 13‐month‐old infants were conducted to investigate infants' ability to use an object's material properties to guide their object‐directed actions. In study 1, 9‐ and 11‐month‐old infants played in an exploration phase with two objects made of different materials, one very heavy and the other one light and playable. Subsequently, when given the choice between both objects in a preferential reaching task, only the 11‐month‐olds' used the object's material information to remember and choose the lighter object. In study 2, 11‐ and 13‐month‐old infants underwent the same exploration phase. In the test phase, novel objects made of the same materials were offered. The 13‐ but not the 11‐month‐olds chose the objects made from the same material as the lighter object in the exploration phase. Additionally, infants' performances in the reaching task were positively correlated with their exploratory behaviour during the exploration phase. Altogether, the studies show a developmental progression in the use of an object's material information to guide infants' action. The results are discussed in respect to infants' perception of object properties and their implications for the development of physical knowledge. Copyright © 2010 John Wiley & Sons, Ltd.

Perception of object number through an aperture by human infants

Perception of object number through an aperture by 10- and 12-month-old infants was investigated. Only 12-month-old infants perceived the number of objects. The findings support the conclusion that the perception of object properties over time emerges late in the 1st year.