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This paper presents a model based robust control scheme for tail-sitter hybrid Unmanned Aerial Vehicles (UAVs) in forward transition phase. To tackle the problem from high nonlinearity and uncertainties in transition dynamics, a comprehensive model form is constructed, and a so-called Robust Perfect Tracking (RPT) control method is utilized in attitude tracking. Experiment results are given to demonstrate...
A nonlinear model of a flapping-wing micro aerial vehicle (MAV) is built in which the load acceleration and equivalent moment are formulated linearly in the body frame. The aerodynamic force and moment are not considered directly because the mass and moment of inertia of the flapping-wing MAV are too tiny. The visual measurement system (VMS) is taken to measure the flight data such as the position...
Emerging nonvolatile memory technologies (NVRAM) promise the performance of DRAM with the persistence of disk. However, constraining NVRAM write order, necessary to ensure recovery correctness, limits NVRAM write concurrency and degrades throughput. We require new memory interfaces to minimally describe write constraints and allow high performance and high concurrency data structures. These goals...
In this paper, we present a vision-based relative sensing system for UAVs to realize leader-follower formation flight without inter-vehicle communication. A monocular camera is mounted on the follower to detected the leader and measure the relative distance by using the geometry information of the leader without artificial markers. The measured relative distance is utilized to estimate the velocity...
A complete flight control scheme with detailed design methodology is proposed for an indoor miniature coaxial helicopter with fixed collective pitch. To avoid system complexity and the problem of minimum phase control, the helicopter dynamic model is decomposed into two cascaded subsystems: an inner one for attitude and heading control and the outer one for trajectory control. H-infinity control technique...
The paper presents a control scheme to the formation flight of a pair of unmanned rotorcraft. A leader-follower formation strategy is adopted and it is realized by utilizing the robust and perfect tracking (RPT) control approach. More specifically, individual RPT flight control laws are implemented in each aircraft, while the measurements from its neighbor and its own sensors are both taken into account...
Starting from experiments, this paper revealed influencing factors of effective width of photo-electric sensors, analyzed some reasons why effective width gave rise to acceleration measurement errors, and raised several improvement methods.
We demonstrate a highly reproducible acceleration of a high-quality electron bunch injected into the laser wake field accelerator with the help of a countercrossing laser pulse. In our experiments, the wake field is generated by a subrelativistic laser pulse; the second laser pulse collides with the first pulse at 135 , realizing optical injection of electron bunch into the wake field. Because the...
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