A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

Meeting abstrac

Characteristics of Three Miniature Bio-inspired Optic Flow Sensors in Natural Environments

Considerable attention has been paid during the last decade to vision-based navigation systems based on optic flow (OF) cues. OF-based systems have been implemented on an increasingly large number of sighted autonomous robotic platforms. Nowadays, the OF is measured using conventional cameras, custom-made sensors and even optical mouse chips. However, very few studies have dealt so far with the reliability of these OF sensors in terms of their precision, range and sensitivity to illuminance variations. Three miniature custom-made OF sensors developed at our laboratory, which were composed of photosensors connected to an OF processing unit were tested and compared in this study, focusing on their responses and characteristics in real indoor and outdoor environments in a large range of illuminance. It was concluded that by combining a custom-made aVLSI retina equipped with Adaptive Pixels for Insect-based Sensor (APIS) with a bio-inspired visual processing system, it is possible to obtain highly effective miniature sensors for measuring the OF under real environmental conditions

Optic Flow Regulation in Unsteady Environments: A Tethered MAV Achieves Terrain Following and Targeted Landing Over a Moving Platform

International audienceThe present study deals with the risky and daunting tasks of flying and landing in non-stationary environments. Using a two Degree-Of-Freedom (DOF) tethered micro-air vehicle (MAV), we show the benefits of an autopilot dealing with a variable - the optic flow - which depends directly on two relative variables, the groundspeed and the groundheight. The micro-helicopter was shown to follow the ups and downs of a rotating platform that was also oscillated vertically. At no time did the MAV know in terms of ground height whether it was approaching the moving ground or whether the ground itself was rising to it dangerously. Nor did it know whether its current groundspeed was caused only by its forward thrust or whether it was partly due to the ground moving backwards or forwards. Furthermore, the MAV was shown to land safely on a platform set into motion along two directions, vertical and horizontal. This paper extends to non-stationary environments a former approach that introduced the principle of ``optic flow regulation'' for altitude control. Whereas in the former approach no requirement was set on the robot's landing target, the target's elevation angle was used here in a second feedback loop that gradually altered the robot's pitch and therefore its airspeed, leading to smooth landing in the vicinity of the target. Whether dealing with terrain following or landing, the MAV followed followed appropriately the unpredictable changes in the environment although it had no explicit knowledge of groundheight and groundspeed. The MAV did not make use of any rangefinders or velocimeters and was simply equipped with a 2-gram vision-based autopilot