Flying robots have unique advantages in the exploration of cluttered environments such as caves or collapsed buildings. Current systems, however, have difficulty in dealing with the large amount of ...obstacles inherent to such environments. Collisions with obstacles generally result in crashes from which the platform can no longer recover. This paper presents a method to design active uprighting mechanisms for protected rotorcraft-type flying robots that allow them to become upright and subsequently take off again after an otherwise mission-ending collision. This method is demonstrated on a tailsitter flying robot, which is capable of consistently uprighting after falling on its side using a spring-based "leg" and returning to the air to continue its mission.
Research made over the past decade shows the use of increasingly complex methods and heavy platforms to achieve autonomous flight in cluttered environments. However, efficient behaviors can be found ...in nature where limited sensing is used, such as in insects progressing toward a light at night. Interestingly, their success is based on their ability to recover from the numerous collisions happening along their imperfect flight path. The goal of the AirBurr project is to take inspiration from these insects and develop a new class of flying robots that can recover from collisions and even exploit them. Such robots are designed to be robust to crashes and can take-off again without human intervention. They navigate in a reactive way, bump into obstacles, and unlike conventional approaches, they don't need heavy modeling in order to fly autonomously. We believe that this new paradigm will bring flying robots out of the laboratory and allow them to tackle unstructured, cluttered environments. This paper aims at presenting the vision of the AirBurr project, as well as the latest results in the design of a platform capable of sustaining collisions and self-recovering after crashes.
Because of their low weight, cost and energy consumption, optic-flow sensors attract growing interest in robotics for tasks such as self-motion estimation or depth measurement. Most applications ...require a large number of these sensors, which involves a fair amount of calibration work for each setup. In particular, the viewing direction of each sensor has to be measured for proper operation. This task is often cumbersome and prone to errors, and has to be carried out every time the setup is slightly modified. This paper proposes an algorithm for viewing direction calibration relying on rate gyroscope readings and a recursive weighted linear least square estimation of the rotation matrix elements. The method only requires the user to realize random rotational motions of its setup by hand. The algorithm provides hints about the current precision of the estimation and what motions should be performed to improve it. To assess the validity of the method, tests were performed on an experimental setup and the results compared to a precise manual calibration. The repeatability of the gyroscope-based calibration process reached ±1.7° per axis.
The evolutionarily conserved POT1 protein binds single‐stranded G‐rich telomeric DNA and has been implicated in contributing to telomeric DNA maintenance and the suppression of DNA damage checkpoint ...signaling. Here, we explore human POT1 function through genetics and proteomics, discovering that a complete absence of POT1 leads to severe telomere maintenance defects that had not been anticipated from previous depletion studies in human cells. Conditional deletion of POT1 in HEK293E cells gives rise to rapid telomere elongation and length heterogeneity, branched telomeric DNA structures, telomeric R‐loops, and telomere fragility. We determine the telomeric proteome upon POT1‐loss, implementing an improved telomeric chromatin isolation protocol. We identify a large set of proteins involved in nucleic acid metabolism that engage with telomeres upon POT1‐loss. Inactivation of the homology‐directed repair machinery suppresses POT1‐loss‐mediated telomeric DNA defects. Our results unravel as major function of human POT1 the suppression of telomere instability induced by homology‐directed repair.
Synopsis
Shelterin protein POT1 binds the single‐stranded telomeric DNA. Here, human POT1 is shown to prevent association of telomeres with recombination enzymes, which cause formation of branched telomeric DNA, R‐loop formation, telomere elongation and telomere fragility.
Complete deletion of POT1 in human cell lines leads to rapid telomere elongation, branched telomeric DNA structures, telomeric R‐loops and telomere fragility.
POT1‐loss phenotypes are suppressed by inactivation of the homologous recombination machinery.
A 2‐step quantitative telomeric chromatin isolation protocol (QTIP) allows comprehensive identification of proteins accumulating at POT1‐deprived telomeres.
Complete loss of the telomeric ssDNA‐binding protein in human cells induces telomeric phenotypes not anticipated from previous knockdown studies, including telomere elongation, R‐loop formation, and chromatin proteome alterations.
A Collision-resilient Flying Robot Briod, Adrien; Kornatowski, Przemyslaw; Zufferey, Jean-Christophe ...
Journal of field robotics,
July/August 2014, Volume:
31, Issue:
4
Journal Article
Peer reviewed
Open access
Flying robots that can locomote efficiently in GPS‐denied cluttered environments have many applications, such as in search and rescue scenarios. However, dealing with the high amount of obstacles ...inherent to such environments is a major challenge for flying vehicles. Conventional flying platforms cannot afford to collide with obstacles, as the disturbance from the impact may provoke a crash to the ground, especially when friction forces generate torques affecting the attitude of the platform. We propose a concept of resilient flying robots capable of colliding into obstacles without compromising their flight stability. Such platforms present great advantages over existing robots as they are capable of robust flight in cluttered environments without the need for complex sense and avoid strategies or three‐dimensional mapping of the environment. We propose a design comprising an inner frame equipped with conventional propulsion and stabilization systems enclosed in a protective cage that can rotate passively thanks to a three‐axis gimbal system, which reduces the impact of friction forces on the attitude of the inner frame. After addressing important design considerations thanks to a collision model and validation experiments, we present a proof‐of‐concept platform, named GimBall, capable of flying in various cluttered environments. Field experiments demonstrate the robot's ability to fly fully autonomously through a forest while experiencing multiple collisions.
It has been shown that long-chain n-3 polyunsaturated fatty acids (n-3 PUFAs) could act synergistically with 5-fluorouracil (5-FU) to kill cancer cells. To facilitate their simultaneous transport in ...the bloodstream, we synthesized, for the first time, liposomes (LIPUFU) containing 5-FU in the aqueous core and docosahexaenoic acid (DHA)/eicosapentaenoic acid (EPA) at a ratio of 1:2 in the lipid bilayer. LIPUFU werestable with uniform size of 154 ± 4 nm, PDI of 0.19 ± 0.03 and zeta potential of -41 ± 2 mV. They contained 557 ± 210 μmol/l DHA, 1467 ± 362 μmol/l EPA, and 9.8 ± 1.1 μmol/l 5-FU. Control liposomes without (LIP) or with only 5-FU (LIFU) or n-3 PUFAs (LIPU) were produced in a similar way. The effects of these different liposomal formulations on the cell cycle, growth, and apoptosis were evaluated in two human colorectal cancer (CRC) cell lines differing in sensitivity to 5-FU, using fluorescence-activated cell sorting analyses. LIPUFU were more cytotoxic than LIP, LIFU, and LIPU in both LS174T (p53
+/+
, bax
−/−
) and HT-29 (p53
−/0
, bax
+/+
) cell lines. Similar to LIFU, LIPUFU increased the percentage of cells in S phase, apoptosis, and/or necrosis. The cytotoxic potential of LIPUFU was confirmed
in vivo
by tumor growth inhibition in the chicken chorioallantoic membrane model. These results suggest that LIPUFU could be considered to facilitate the simultaneous transport of 5-FU and n-3 PUFAs to the tumor site, in particular in case of CRC liver metastases.
Mobile robots are valuable tools for education because of both the enthusiasm they raise and the multidisciplinary nature of robotics technology. Mobile robots give access to a wide range of fields, ...such as complex mechanics, sensors, wireless transmission, mathematics, and computer science. However, despite their potential as educational tools, robots are still not as widespread in schools as they could be. In this article, we identify five key reasons: lack of diversity, high cost, noninclusive design, lack of educational material, and lack of stability over time. Then, we describe our answers to these problems, as we implemented them in the Thymio project: a mature mass-produced open-hardware robot, at a low price, with a multiage and gender-neutral feature set, and with a design promoting creativity, facilitating learning, and providing a wide range of interaction possibilities from built-in behaviors to text programming, passing through different visual programming environments. We highlight some neglected key issues that differentiate open-source hardware from open-source software, for instance the legal uncertainty of designing open hardware using professional computer-aided design (CAD) tools and the difficulty to distribute the development. Our solution to these being to increase the awareness of CAD editors to open-source hardware and to provide a two-layer development model for hardware.
We aim at developing autonomous miniature hovering flying robots capable of navigating in unstructured GPS-denied environments. A major challenge is the miniaturization of the embedded sensors and ...processors that allow such platforms to fly by themselves. In this paper, we propose a novel ego-motion estimation algorithm for hovering robots equipped with inertial and optic-flow sensors that runs in real-time on a microcontroller and enables autonomous flight. Unlike many vision-based methods, this algorithm does not rely on feature tracking, structure estimation, additional distance sensors or assumptions about the environment. In this method, we introduce the
translational optic-flow direction constraint
, which uses the optic-flow direction but not its scale to correct for inertial sensor drift during changes of direction. This solution requires comparatively much simpler electronics and sensors and works in environments of any geometry. Here we describe the implementation and performance of the method on a hovering robot equipped with eight 0.65 g optic-flow sensors, and show that it can be used for closed-loop control of various motions.
On 7 February 2015 in Dubai, United Arab Emirates (UAE), with applause from an international jury of drone experts, UAE ministers, and international dignitaries, His Highness Mohammed bin Rashid Al ...Maktoum handed us a US$1 million check and the first-place prize of the UAE Drones for Good Award, the "World Cup of drones."
PDF
