Attitude and Altitude Tracking of Hexacopter via LQR with Integral Action

A controller is designed for hexacopter platform to achieve accurate tracking of altitude and attitude commands under the influence of severe disturbances. The main aim is designing a controller that can be tuned easily to satisfy desired performance requirements. For this purpose, multi-variable control method LQR is combined with PID structure which provides valuable physical insight in tuning process. Integral states are added to the system dynamics to have PID structure. Command generator is used to have trajectory independent optimal gain matrix which is advantageous for real time application. Time domain requirements are satisfied by tuning state and input weight matrices(Q and R) systematically. By this way, it is also possible to tune the controller for hexacopter platforms with different parameters(mass, inertia, etc.) without much effort. Controller performance is analyzed by using nonlinear dynamic model which includes a basic drag model, disturbance effects, actuator and sensor dynamics. Tracking performance and disturbance rejection properties are satisfactory according to numerical results. Controller structure is suitable for real time implementation with the help of simplified tuning process and a hexacopter platform is under construction for experimental verification