Second Order Sliding Mode Controller for Altitude and Yaw Control of Quadcopter

Unmanned aerial vehicles are very attractive to industrial practitioners due to their high maneuverability and ability to perform vertical take-off landing. The accuracy in altitude and yaw movement control become vital for vertical take-off landing. This paper examines and compares the ability of a second order sliding mode controller in altitude and yaw tracking control of a quadcopter against the traditional proportional-derivative controller. Both controllers were designed and numerically analyzed on a mathematical model of a quadcopter. Two types of input were generated, namely; slow-rate input in which only one set point was set, and fast-rate input in which more than one set point was set. Both inputs were injected into the system respectively and both controllers were evaluated and compared in terms of maximum overshoot, settling time and root-mean-square tracking error. Simulation results showed that second order sliding mode controller outperformed traditional linear controller in all considered performance indicators for both hovering and yaw motion control. A reduction of more than 80% has been achieved in terms of maximum overshoot. The chattering effect was reduced by using logistic function. The effectiveness of this controller would promote its application in real-time due to its great control performances compared to standard controller.