Dealing with midair collisions in dense collective aerial systems

The idea of creating collective aerial systems is appealing because several rather simple flying vehicles could join forces to cover a large area in little time in applications such as monitoring, mapping, search and rescue, or airborne communication relays. In most of these scenarios, a fleet of cooperating vehicles is dispatched to a confined airspace area and requested to fly close to a nominal altitude. Moreover, depending on the task each vehicle is assigned to, individual flight trajectories in this essentially two‐dimensional space may interfere, resulting in disastrous collisions. This paper begins by introducing a probabilistic model to predict the rate of midair collisions that would occur if nothing is done to prevent them. In a second step, a control strategy for midair collision avoidance is proposed, which is interesting because it requires only local communication and information about flight altitudes. The proposed strategy is systematically analyzed in theory and simulation as well as in experiments with five physical aerial vehicles. A significant reduction in collision rates can be achieved. Statistically, values close to zero are possible when the swarm's density is below an application‐dependent threshold. Such low collision rates warrant an acceptable level of confidence in collision‐free operation of a physical swarm. © 2011 Wiley Periodicals, Inc.     

Flying over the reality gap: From simulated to real indoor airships

Because of their ability to naturally float in the air, indoor airships (often called blimps) constitute an appealing platform for research in aerial robotics. However, when confronted to long lasting experiments such as those involving learning or evolutionary techniques, blimps present the disadvantage that they cannot be linked to external power sources and tend to have little mechanical resistance due to their low weight budget. One solution to this problem is to use a realistic flight simulator, which can also significantly reduce experimental duration by running faster than real time. This requires an efficient physical dynamic modelling and parameter identification procedure, which are complicated to develop and usually rely on costly facilities such as wind tunnels. In this paper, we present a simple and efficient physics-based dynamic modelling of indoor airships including a pragmatic methodology for parameter identification without the need for complex or costly test facilities. Our approach is tested with an existing blimp in a vision-based navigation task. Neuronal controllers are evolved in simulation to map visual input into motor commands in order to steer the flying robot forward as fast as possible while avoiding collisions. After evolution, the best individuals are successfully transferred to the physical blimp, which experimentally demonstrates the efficiency of the proposed approach. Jean-Christophe Zufferey and Alexis Guanella contributed equally to this work.     

Coping With Chronic Lower Back Pain: Designing and Testing the Online Tool ONESELF

A website was designed in order to help patients with chronic lower back pain (cLBP) to cope with their condition, relying on the concept of health literacy. A sample of 748 chronic or potentially chronic LBP patients were asked to regularly visit the site for a period of 12 months. The intervention was evaluated quantitatively (both preuse and postuse surveys, logfiles) and qualitatively. Users appear to have taken less painkillers than before in the period they accessed the site. Most users reported that the site contributed to increasing their knowledge, and helped them managing their back pain. Communication with doctors, family, and colleagues improved. Qualitative evaluation showed several positive effects including self‐comprehension, improvement of argumentative abilities, orientation, and self‐confidence.     

Steerable miniature jumping robot

Jumping is used in nature by many small animals to locomote in cluttered environments or in rough terrain. It offers small systems the benefit of overcoming relatively large obstacles at a low energetic cost. In order to be able to perform repetitive jumps in a given direction, it is important to be able to upright after landing, steer and jump again. In this article, we review and evaluate the uprighting and steering principles of existing jumping robots and present a novel spherical robot with a mass of 14 g and a size of 18 cm that can jump up to 62 cm at a take-off angle of 75°, recover passively after landing, orient itself, and jump again. We describe its design details and fabrication methods, characterize its jumping performance, and demonstrate the remote controlled prototype repetitively moving over an obstacle course where it has to climb stairs and go through a window. (See videos 1–4 in the electronic supplementary material.)     

Fatal vascular leak syndrome with extensive hemorrhage, peripheral neuropathy and reactive erythrophagocytosis: an unusual complication of recombinant IL-3 therapy

A 39-year-old patient with severe aplastic anemia (AA), resistant to therapy, received recombinant human IL-3 (rhIL-3) on a phase I/II trial. During treatment she developed disseminated skin lesions, suggestive of vasculitis, and severe progressive peripheral neuropathy culminating in complete paralysis. She died 25 days after beginning treatment from profuse bleeding. On autopsy, evidence of vascular leaks with widespread bleeding and extensive hemorrhagic involvement of peripheral nerves was found. An additional feature was massive reactive erythrophagocytosis in lymph nodes, spleen and bone marrow. The coincidence between rhIL-3 administration and the dramatic events suggest a causal relation. As a possible pathogenic mechanism, an rhIL-3 induced excessive stimulation of macrophages and production of secondary cytokines such as tumor necrosis factor (TNF) is suggested. TNF is considered as a major factor in the development of both a vascular leak and reactive erythrophagocytosis. This case report can be regarded as an example of the possible unusual pathologic phenomena we may expect to see in the near future with increasing use of growth factors.