UAV quadrotor

This paper presents the modelling of a four rotor vertical take-off and landing (VTOL) unmanned air vehicle known as the quadrotor aircraft. The paper presents a new model design method for the flight control of an autonomous quad rotor. The paper describes the controller architecture for the quadrotor as well. The dynamic model of the quad-rotor, which is an under actuated aircraft with fixed four pitch angle rotors, will be described. The Modeling of a quadrotor vehicle is not an easy task because of its complex structure. The aim is to develop a model of the vehicle as realistic as possible. The model is used to design a stable and accurate controller. This paper explains the developments of a PID (proportional-integral-derivative) control method to obtain stability in flying the Quad-rotor flying object. The model has four input forces which are basically the thrust provided by each propeller connected to each rotor with fixed angle. Forward (backward) motion is maintained by increasing (decreasing) speed of front (rear) rotor speed while decreasing (increasing) rear (front) rotor speed simultaneously which means changing the pitch angle. Left and right motion is accomplished by changing roll angle by the same way. The front and rear motors rotate counter-clockwise while other motors rotate clockwise so that the yaw command is derived by increasing (decreasing) counter-clockwise motors speed while decreasing (increasing) clockwise motor speeds.

One of the main source of danger for people practising activities in mountain environments is avalanches. In the early 70s has been commercialized the first model of avalanche beacon transceiver: a device, composed by a transmitter and a receiver, specialized to the purpose of finding people buried under the snow. Since 2013, project SHERPA is working to develop ground and aerial robots to support human in the search of missing people in avalanches.
The aim of this dissertation is to provide a way to interface an avalanche beacon receiver (ARTVA) with the autopilot module mounted on a quad-copter drone, and to study and realize a software implementation of two automatic search algorithms, with the intention of speeding up search operations with drones.
First we will focus on interfacing the ARTVA system with a quad-copter autopilot module, named Pixhawk. This module embed a software, named PX4, which runs on a real-time operating system (RTOS), and have several connection ports, among which there is the serial one that we will use for our purpose. Then we will analyse how to use the data coming from the ARTVA receiver to construct and implement the two search algorithms. The idea is to generate set-points, based on the information coming from the avalanche beacon receiver, and use them to feed the position controller which is implemented in the PX4 firmware. Finally, we will execute simulations, provide results, and investigate if a practical implementation is possible and what are the relative issues.

In this paper a robust controller for attitude stabilization of a Quadrotor UAV is proposed. For this we design a Takagi-Sugeno (T-S) model for Quadrotor modelling, and then we use Linear Matrix Inequality (LMI), and PDC (Parallel Disturbance Compensation) technique to design a nonlinear state feedback controller with pole placement in a pre-specified region of the operating space.The stabilityof the whole closed-loop system is investigated using quadratic Lyapunovfunction.To demonstrateits usefulness, the proposed design methodology is applied to the problem ofQuadrotor attitude stabilization. Simulation results show that the proposedLMI-based design methodology yields good transient performance.In addition, it is observed that the proposed state feedback controller provides superior stability robustness againstparameter variationsand measurement noise.

This paper considers the control problem for an underactuated quadrotor UAV system in presence of sensor faults. Dynamic modelling of quadrotor while taking into account various physical phenomena, which can influence the dynamics of a flying structure is presented. Subsequently, a new control strategy based on robust integral backstepping approach using sliding mode and taking into account the sensor faults is developed.
Lyapunov based stability analysis shows that the proposed control strategy design keep the stability of the closed loop dynamics of the quadrotor UAV even after the presence of sensor failures. Numerical simulation results are provided to show the good tracking performance of proposed control laws.

In this paper we present a Takagi-Sugeno (T-S) model for Quadrotor modelling. This model is developed using multiple model approach, composed of three locally accurate models valid in different region of the operating space. It enables us to model the global nonlinear system with some degree of accuracy. Once the T-S model has been defined it is claimed to be relatively straightforward to design a controller with the same strategy of T-S model. A nonlinear state feedback controller based on Linear Matrix Inequality (LMI), and PDC technique with pole placement constraint is synthesized. The requirements of stability and pole-placement in LMI region are formulated based on the Lyapunov direct method. By recasting these constraints into LMIs, we formulate an LMI feasibility problem for the design of the nonlinear state feedback controller. This controller is applied to a nonlinear Quadrotor system, which is one of the most complex flying systems that exist. A comparative study between controller with stability constraints and controller with pole placement constrains is made. Simulation results show that the controller with pole placement constrains yields good tracking performance. The designed T-S model is validated using Matlab Simulink.