Resumo:
The use of PID controllers in quadrotors has gained popularity and are the preferred
choice for regulating and stabilizing these inherently unstable systems thanks to its simplicity
and effectiveness. On the other hand, nonlinear controllers still represent a challenge
for practical implementation, mainly due to their complexity of programming, reliability
and certification. This paper presents a robust nonlinear controller for quadrotor control,
based on Sliding Mode Control and with a simple structure and easy to implement in order
to encourage its future use in commercial controller boards. The proposed controller,
called Universal Integral Regulator, also has properties that make it an excellent choice
in passive fault-tolerant control schemes such as: (i) disturbance and model uncertainties
rejection capabilities, (ii) guaranteed steady state zero tracking error added with an
anti wind-up capability, (iii) reduced chattering and especially, (iv) it does not require
previous and detailed knowledge of the plant model which facilitates its experimental
implementation. The proposed controller’s performance is examined and compared to
classical PID through numerical simulations and real world experiments on a 3 Degrees
of Freedom quadrotor platform in the presence of several actuator faults (Locked-in-Place
and Loss of Effectiveness). The results demonstrated the enhanced tracking performance
and overall superiority of the proposed Universal Integrative Regulator control law compared
to the conventional PID controller. This was evidenced through both qualitative
and quantitative comparisons of performance indices. Specifically, the Universal Integrative
Regulator achieved at least a 50% reduction in tracking error relative to the PID
controller, highlighting its effectiveness in improving control accuracy.
