Quadrotor Trajectory-Tracking Control with Actuator Saturation

Abstract

As a very serious problem for control systems, actuator saturation often leads to an unstable system. The maneuvering flight of quadrotors may lead to actuator saturation, which commonly affects the flight quality, including trajectory-tracking accuracy. Quadrotors usually adopt double-closed-loop control, of which the outer loop is the position control used to calculate the desired attitude angle and the inner loop is the attitude control used to generate control actions for the vehicle. To address actuator saturation during the maneuvering flight of quadrotors, an attitude controller based on the conditioned super-twisting algorithm (CSTA) was designed. The sign functions in CSTA were replaced by a hyperbolic tangent function, which suppresses the chattering of CSTA. In order to improve the rapidity of the improved controller, the tanh-CSTA (TCSTA), a gain adjustment factor was utilized. The rapidity and smoothness of the controller can be satisfied by adjusting the gain factor. Additionally, a sliding surface was designed according to the characteristics of the quadrotor control structure, so that the TCSTA controller can be applied to the second-order system. The performances of the designed improved controller were simulated using MATLAB, and the results showed that the designed controller is more robust than the PID controller. Moreover, compared with the CSTA controller, the chattering of the designed controller was obviously suppressed without reducing the control accuracy.

ASMC and ARSMC Cascaded Controller Design for QUAVs With Time-Varying Load and Unknown Disturbances

“…Lemma 1( [44]): considering the attitude subsystem(6) with the upper bounds of unknown disturbances (7) and the designed adaptive laws (20), there exist b ϕi , b θi and b ψi in (7) such that b i0 ≤ 0, b i1 ≤ 0 and b i2 ≤ 0, where b ij (j = 0, 1, 2) are shown in (22).…”

“…It is well known that the QUAVs are under-actuated, strongly nonlinear and coupling systems, thus the stability analysis and controller design for QUAVs are still challenging [5], [6]. Fortunately, as to these issues, some efforts have been tried by scholars, and lots of results were achieved [7]- [9]. Moreover, there are numerous control strategies, such as, Proportional Integral Differential (PID) [10], Active Disturbance Rejection Control (ADRC) [11], Sliding Mode Control (SMC) [12], etc., have been proposed for the control of QUAVs.…”