Semi-active control of light aircraft landing gear using hardware in the loop simulation structure

In this thesis, semi-active Adaptive Backstepping (ABS) and active Linear Quadratic Regulator (LQR) control were designed to reduce the vibrations of the aircraft suspension system equipped with a magnetorheological (MR) damper. The designed LQR controller has been applied to the system semi-actively using the inverted version of the active force by inverse damper model. The effectiveness of the designed controllers has been tested with the Hardware-in-the-Loop (HIL) structure established in a laboratory environment. The effectiveness of UGA and LQR control approaches has been tested under random road inputs. In the zero-volt condition where the MR damper is connected but no voltage is applied to the damper, the effectiveness of these control approaches applied to the MR damper has been tested. The proposed UGA control approach has been observed to improve criteria used in the evaluation of suspension systems, such as aircraft body pitch motion, comfort, and suspension working range, compared to the cases it is compared against. In addition to the experimental study, control methods for two different scenarios have been tested in a simulation environment. In the first simulation study, a situation reflecting the dynamics of the front wheel hitting the ground during the aircraft landing was created by using a Multibody Dynamics program, SIMPACK. Then, the created aircraft model was transferred to the MATLAB/Simulink environment, and the dynamic behaviour of the system was examined under the LQR control and Hybrid control which is a combination both of Skyhook and Groundhook control approaches. In the second simulation study, using Newton's 2nd Law, the acceleration and displacement responses of the system were suppressed by LQR control and UGA control for scenarios including the bumps and random road inputs during the taxi movement of the aircraft modelled in the MATLAB/Simulink environment.