1,721,028 research outputs found
Synergistic morphology and feedback control for traversal of unknown compliant obstacles with aerial robots
Full text linkISSN:2041-172
A bioinspired multi-modal flying and walking robot
No full textWith the aim to extend the versatility and adaptability of robots in complex environments, a novel multi-modal flying and walking robot is presented. The robot consists of a flying wing with adaptive morphology that can perform both long distance flight and walking in cluttered environments for local exploration. The robotʼs design is inspired by the common vampire bat Desmodus rotundus, which can perform aerial and terrestrial locomotion with limited trade-offs. Wings' adaptive morphology allows the robot to modify the shape of its body in order to increase its efficiency during terrestrial locomotion. Furthermore, aerial and terrestrial capabilities are powered by a single locomotor apparatus, therefore it reduces the total complexity and weight of this multi-modal robot.NCCR-ROBOTICSLI
The green leafhopper, cicadella viridis (hemiptera, auchenorrhyncha, cicadellidae), jumps with near-constant acceleration
No full textJumping insects develop accelerations that can greatly exceed gravitational acceleration. Although several species have been analysed using different tools, ranging from a purely physical to a morpho-physiological approach, instantaneous dynamic and kinematic data concerning the jumping motion are lacking. This is mainly due to the difficulty in observing in detail events that occur in a few milliseconds. In this study, the behaviour of the green leafhopper, Cicadella viridis, was investigated during the take-off phase of the jump, through high-speed video recordings (8000 frames s-1). We demonstrate that C. viridis is able to maintain fairly constant acceleration during overall leg elongation. The force exerted at the foot-ground interface is nearly constant and differs from the force expected from other typical motion models. A biomechanical model was used to highlight that this ability relies on the morphology of C. viridis hind legs, which act as a motion converter with a variable transmission ratio and use the time-dependent musculo-elastic force to generate a nearly constant thrust at the body-ground interface. This modulation mechanism minimizes the risk of breaking the substrate thanks to the absence of force peaks. The results of this study are of broad relevance in different research fields ranging from biomechanics to robotics. © 2013. Published by The Company of Biologists Ltd
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Investigation of Collective Behaviour and Electrocommunication in the Weakly Electric Fish, Mormyrus rume, through a biomimetic Robotic Dummy Fish
No full textA robotic fish has been developed to create a mixed bio-hybrid system made up of weakly electric fish and a mobile dummy fish. Weakly electric fish are capable of interacting with each other via sequences of self-generated electric signals during electrocommunication. Here we present the design of an artificial dummy fish, which is subsequently tested in behavioural experiments. The robot consists of two parts: a flexible tail that can move at different frequencies and amplitudes, performing a carangiform oscillation, and a rigid head containing the motor for the tail oscillation. The dummy fish mimics the weakly electric fish Mormyrus rume in morphology, size and electric signal generation. In order to study electrical interactions, the dummy fish is equipped with ten electrodes that record electric signals of nearby real fish and generate electric dipole fields around itself that are similar to those produced by real fish in both waveform and sequence. Behavioural experiments demonstrate that the dummy fish is able to recruit both single individuals and groups of M. rume from a shelter into an exposed area. The development of an artificial dummy fish may help to understand fundamental aspects of collective behaviour in weakly electric fish and the properties necessary to initiate and sustain it in closed-loop feedback experiments based on electrocommunication.LI
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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