Aerospace vehicles

The number of applications of UAVs has been constantly growing in the last decade. They include not only military applications but also civil applications as aerial surveillance of traffic in highways, support in search and rescue operations, intervention in hostile environments, etc. These applications require aerial robots or UAVs which are safe with respect to the persons around them. The UAVs should also be reliable and have the capacity to navigate autonomously in a prescribed trajectory. For safety reasons the total weight of the UAV should be as low as possible. The achievement of this objective certainly requires innovations from both technological and scientific points of view. Most of the UAV developed so far can be classified as 

  1. fixed-wings aircraft (airplanes), 
  2. rotary-wing aircraft or rotorcrafts (helicopters)

The rotary-wins aerial vehicles, such as helicopters, have distinct advantages over conventional fixed-wing aircraft and blimps on surveillance and inspections tasks, since they can take-off and land in limited space and can easily hover above targets. Moreover, helicopters have the advantage of superior manoeuvrability. Unfortunately, this advantage makes helicopters very hard to control, requiring sophisticated sensors and fast on-board computation. The design of unmanned aerial vehicles involves the integration of various steps such as design, selection of sensors and developing controllers. These steps cannot be treated separately. Design of flying robots, UAVs and specially helicopters is an active field. Various UAV designs and subsystems have been introduced in recent years for both military and general purpose. There are also various designs of multi-rotor helicopters, VTOL aircraft, quad-rotors and coaxial helicopters.

The UAV-team of LAFMIA develops an approach that covers both fundamental research as well as experimental platform development based on rotor small helicopters. This team has designed and constructed several configurations such as mono-rotors, birotors, trirotors, quadrirotors as well as preliminary prototypes of VTOL’s (Vertical Take-Off and Landing) convertible airplanes. Nonlinear control strategies for stabilization of such systems have been proposed considering actuators constraints. An important effort has also been devoted to the development of experimental UAV platforms. Various rotorcraft vehicles have been developed using onboard real-time control algorithms. Embedded real-time architectures, sensors integration, and implementation of proposed controllers have then been achieved. Contributions are regularly published in well known international journals and conferences. This team also currently works on the use of vision for achieving navigational tasks like hovering, vertical landing and obstacles avoidance.