BACKSTEPPING APPROACH FOR DESIGN OF CASCADED PID CONTROLLER WITH GUARANTEED TRAJECTORY TRACKING PERFORMANCE FOR MICRO-AIR UAV
Abstract
Flight controllers for micro-air UAVs are generally designed using Proportional-
Integral-Derivative (PID) methods, where the tuning of gains is difficult and time-consuming,
and performance is not guaranteed. In this thesis, we develop a rigorous method based on
the sliding mode analysis and nonlinear backstepping to design a PID controller with guaranteed
performance. This technique provides the structure and gains for the PID controller,
such that a robust and fast response of the UAV for trajectory tracking is achieved. First, the
second-order sliding variable errors are used in a rigorous nonlinear backstepping design to
obtain guaranteed performance for the nonlinear UAV dynamics. Then, using a small angle
approximation and rigorous geometric manipulations, this nonlinear design is converted
into a PID controller whose structure is naturally determined through the backstepping procedure.
PID gains that guarantee robust UAV performance are finally computed from the
sliding mode gains and from stabilizing gains for tracking error dynamics. We prove that
the desired Euler angles of the inner attitude controller loop are related to the dynamics
of the outer backstepping tracker loop by inverse kinematics, which provides a seamless
vi
connection with existing built-in UAV attitude controllers. We implement the proposed
method on actual UAV, and experimental flight tests prove the validity of these algorithms.
It is seen that our PID design procedure yields tighter UAV performance than an existing
popular PID control technique.
The publication resulted from this thesis is listed below:
Kartal, Y., Kolaric, P., Lopez, V. et al. Control Theory Technol. (2019). https://doi.org/10.1007/s11768-
020-9145-y