ABSTRACT
This work is aimed at modeling and carrying out state space analysis of a micro-UAV (unmanned aerial vehicle) which is based on a modified radio controlled (RC) coaxial helicopter. The modification involved incorporating payload such as: GPS (global positioning system) module, Arduino microcontroller board and the Arduino Wi-Fi shield. The modeling involved the development of a non-linear rigid body model on the basis of resolving forces and moments that act on the micro-UAV using Euler-Newton formulation. In order to carry out the state space analysis of controllability and observability, the non-linear model was linearized using the small perturbation method. The desired performance specifications are: damping ratio 0.6 ? ? ? 1, peak overshoot ? 5% p M and the system should be asymptotically stable. The micro-UAV model was shown to be controllable and observable even though asymptotically unstable due to the presence of positive real roots (eigenvalues on the right hand of the s-plane, RHP) and repetitive zero real roots on the s-plane. This indicated that the damping ratio of -1 and peak overshoot of 69.2% fell outside the desired specifications. Also, the time response analysis carried out revealed unstable state responses in the dynamics and kinematics of the micro-UAV. A linear optimal linear quadratic regulator (LQR) controller was introduced to stabilize the micro-UAV and improved the performance specification with respect to peak overshoot of 4.27% and damping ratio of 0.708. These values fell within the acceptable specifications and the system was also shown to be asymptotically stable as all the eigenvalues were now on the left hand of the splane (LHP). The time response analysis carried out showed stable state responses in dynamics and kinematics of the micro-UAV. The communication link between the prototype micro-UAV and the ground control station was established via a router access point (which was encrypted to prevent unauthorized access) and a program written in visual C# programming language. This was tested in the indoor environment of the Control Laboratory of Department of Electrical and Computer Engineering, Ahmadu Bello University Zaria. The GPS data of longitude, latitude, time stamp and speed at which these data were transmitted from the micro-UAV were monitored at the ground station (a laptop PC with GUI developed program) with the aid of the GPS module, Ardiuno micro-controller and Ardiuno Wi-Fi shield. The received signal strength indicator (RSSI) of the link was in the range -60dBm to - 41dBm operating at a frequency of 2.4GHz and data rate of 5.4Mbit/s.