The Robustness of Linear Quadratic Regulator (LQR) and Linear Quadratic Regulator Tracker (LQRT) Cascaded With Line-Of-Sight (LOS) Guidance Law for Quadrotor to Accomplish SAR Mission

Linear Quadratic Regulator (LQR) algorithm with several patterns is commonly used in quadrotors to examine their capabilities in maintaining positions during search and rescue (SAR) missions. The robustness of conventional LQR and Linear Quadratic Regulator Tracker (LQRT) algorithms cascaded with line-of-sight (LOS) guidance law along a square pattern is compared with and without disturbance and presented in this paper. The systems were analyzed using the root-mean-square error (RMSE) value and time domain response. The results indicate that LQR control without disturbance exhibits a faster response time to reaching the set point, yet it produces a higher overshoot. However, LQRT exhibits a faster settling time and a slight overshoot, while slower in reaching the desired position. Conversely, during the disturbance, LQR control ends with marginally stable for the heave, and the RMSE value remains elevated. Additionally, both end with fluctuated pitch angle position, but LQRT outperforms due to a smaller peak-to-peak deviation. Furthermore, LQRT exhibits a more robust response and stability, with no significant RMSE value change. Therefore, LQRT is the optimal choice for quadrotor utilization in SAR missions and can potentially benefit practitioners, particularly when the mission is under uncertain environment.