A Comparative Study of PID and Nonlinear Backstepping Flight Control Laws for Pixhawk-Based Multicopter

This paper investigates the control strategies for a quadcopter UAV controlled by a Pixhawk-based flight controller. First, the nonlinear mathematical model of a quadcopter has been derived considering its aerodynamic and rotor effects. From this model, it can be seen that the quadcopter is a nonlinear underactuated system which makes its control design challenging. Two control approaches for this quadcopter system have been chosen and analysed here, the linear proportional–integral–derivative (PID) control and the nonlinear Backstepping control approach. Both approaches were adapted for use in the PX4-Pixhawk-based controllers. Their performance was tested with a quadcopter dynamic model and the results were simulated. A comparison of the obtained results indicates that the Backstepping control technique settles > 5 times faster than the PID control and also provides more stability to the system making it the preferable control strategy for quadcopters using Pixhawk-based autopilots.