158 research outputs found
Dexterous manipulation of unknown objects using virtual contact points
The manipulation of unknown objects is a problem of special interest in robotics since it is not always possible to have exact models of the objects with which the robot interacts. This paper presents a simple strategy to manipulate unknown objects using a robotic hand equipped with tactile sensors. The hand configurations that allow the rotation of an unknown object are computed using only tactile and kinematic information, obtained during the manipulation process and reasoning about the desired and real positions of the fingertips during the manipulation. This is done taking into account that the desired positions of the fingertips are not physically reachable since they are located in the interior of the manipulated object and therefore they are virtual positions with associated virtual contact points. The proposed approach was satisfactorily validated using three fingers of an anthropomorphic robotic hand (Allegro Hand), with the original fingertips replaced by tactile sensors (WTS-FT). In the experimental validation, several everyday objects with different shapes were successfully manipulated, rotating them without the need of knowing their shape or any other physical property.Peer ReviewedPostprint (author's final draft
Methods and Sensors for Slip Detection in Robotics: A Survey
The perception of slip is one of the distinctive abilities of human tactile sensing. The sense of touch allows recognizing a wide set of properties of a grasped object, such as shape, weight and dimension. Based on such properties, the applied force can be accordingly regulated avoiding slip of the grasped object. Despite the great importance of tactile sensing for humans, mechatronic hands (robotic manipulators, prosthetic hands etc.) are rarely endowed with tactile feedback. The necessity to grasp objects relying on robust slip prevention algorithms is not yet corresponded in existing artificial manipulators, which are relegated to structured environments then. Numerous approaches regarding the problem of slip detection and correction have been developed especially in the last decade, resorting to a number of sensor typologies. However, no impact on the industrial market has been achieved. This paper reviews the sensors and methods so far proposed for slip prevention in artificial tactile perception, starting from more classical techniques until the latest solutions tested on robotic systems. The strengths and weaknesses of each described technique are discussed, also in relation to the sensing technologies employed. The result is a summary exploring the whole state of art and providing a perspective towards the future research directions in the sector
Visual Perception of Garments for their Robotic Manipulation
TĂ©matem pĹ™edloĹľenĂ© práce je strojovĂ© vnĂmánĂ textiliĂ zaloĹľenĂ© na obrazovĂ© informaci a vyuĹľitĂ© pro jejich robotickou manipulaci. Práce studuje nÄ›kolik reprezentativnĂch textiliĂ v běžnĂ˝ch kognitivnÄ›-manipulaÄŤnĂch Ăşlohách, jako je napĹ™Ăklad tĹ™ĂdÄ›nĂ neznámĂ˝ch odÄ›vĹŻ podle typu nebo jejich skládánĂ. NÄ›kterĂ© z tÄ›chto ÄŤinnostĂ by v budoucnu mohly bĂ˝t vykonávány domácĂmi robotickĂ˝mi pomocnĂky. Strojová manipulace s textiliemi je poptávaná takĂ© v prĹŻmyslu. HlavnĂ vĂ˝zvou Ĺ™ešenĂ©ho problĂ©mu je mÄ›kkost a s tĂm souvisejĂcĂ vysoká deformovatelnost textiliĂ, kterĂ© se tak mohou nacházet v bezpoÄŤtu vizuálnÄ› velmi odlišnĂ˝ch stavĹŻ.The presented work addresses the visual perception of garments applied for their robotic manipulation. Various types of garments are considered in the typical perception and manipulation tasks, including their classification, folding or unfolding. Our work is motivated by the possibility of having humanoid household robots performing these tasks for us in the future, as well as by the industrial applications. The main challenge is the high deformability of garments, which can be posed in infinitely many configurations with a significantly varying appearance
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