The development of miniature flying robots has become a reachable dream thanks to the new sensing and actuating technologies. Micro VTOL 1 systems represent a useful class of flying robots because of their strong abilities for small-area monitoring and building exploration. In this paper, we present the results of two model-based control techniques applied to an autonomous four-rotor micro helicopter called Quadrotor. A classical approach (PID) assuming a simplified dynamics and a modern technique (LQ), based on a more complete model. Various simulations were performed and several tests on the bench validate the control laws. Finally, we present the results of the first test in flight with the helicopter released. These developments are part of the OS4 2 project in our lab 3 .

Abstract-The latest technological progress in sensors, actuators and energy storage devices enables the developments of miniature VTOL 1 systems. In this paper we present the results of two nonlinear control techniques applied to an autonomous micro helicopter called Quadrotor. A backstepping and a sliding-mode techniques. We performed various simulations in open and closed loop and implemented several experiments on the test-bench to validate the control laws. Finally, we discuss the results of each approach. These developments are part of the OS4 2 project in our lab.

Abstract-Recent progress in sensor technology, data processing and integrated actuators has made the development of miniature flying robots fully possible. Micro VTOL 1 systems represent a useful class of flying robots because of their strong capabilities for small-area monitoring and building exploration. In this paper we describe the approach that our lab 2 has taken to micro VTOL evolving towards full autonomy, and present the mechanical design, dynamic modelling, sensing, and control of our indoor VTOL autonomous robot OS43 .

The research on autonomous miniature flying robots has intensified considerably thanks to the recent growth of civil and military interest in Unmanned Aerial Vehicles (UAV). This paper summarizes the final results of the modeling and control parts of OS4 project, which focused on design and control of a quadrotor. It introduces a simulation model which takes into account the variation of the aerodynamical coefficients due to vehicle motion. The control parameters found with this model are successfully used on the helicopter without re-tuning. The last part of this paper describes the control approach (Integral Backstepping) and the scheme we propose for full control of quadrotors (attitude, altitude and position). Finally, the results of autonomous take-off, hover, landing and collision avoidance are presented.

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