1.
INTRODUCTION
The quadrotor UAV is a vertical take-off and landing
aircraft with six degrees of freedom, which can break the
runway limit to land and hover freely
[1]
. Compared to other
UAV platforms, it is characterized by its simple, stable
structure, and super flexibility. Now, the quadrotor UAV is
widely applied in tactical reconnaissance, aerial
photography, electromagnetic interference, short distance
freightage and other fields
[2]
. The research on the quadrotor
UAV has important realistic significance and it has become
one of the hot spots at home and abroad.
At present, a large number of scholars have studied the
quadrotor UAV as a complex non-linear, multi-variable,
under-actuated control system. Simultaneously, a number of
papers have been published on the tracking of quadrotor
UAV. Recently, the application of active disturbance
rejection control(ADRC)
[3-5]
, sliding mode control
[6]
,
predictive control
[7]
, backstepping
[8]
, adaptive control
[9]
and
robust control
[10]
have been proposed to perform position
and attitude control of the quadrotor UAV system.
However, the quadrotor UAV has the characteristics of
nonlinearity, high order, strong coupling and
under-actuated, resulting in its stability analysis and
controller design are difficult.
In the quadrotor UAV control system, SMC is widely
adopted. A sliding mode controller is proposed for the
robust control of both the position and attitude of the
quadrotor UAV
[11]
. An inner and outer loop nonlinear
controller combined with sliding mode control and
backstepping control is designed in this paper
[12]
. This
method adopted the inner loop system control attitude
This work was supported by the National Natural Science Foundation
of China [grant number 61374180, 61603196]; the Natural Science
Foundation of Jiangsu Province of China [grant number BK20150851];
the Project funded by China Postdoctoral Science Foundation [grant
number 2015M581842]; the Project funded by Jiangsu Province
Postdoctoral Science Foundation [grant number 1601259C]; the
Sponsored by NUPTSF [grant number NY215011]; the Postgraduate
Research & Practice Innovation Program of Jiangsu Province[grant
number KYCX17_0793].
subsystem to ensure faster convergence of Euler angle,
However, the stability of the closed-loop system needs to be
further analyzed.
In recent years, adaptive control is also widely used in UAV
systems. Adaptive control system is based on changing the
parameters of the object itself, automatically adjust the
controller parameters to obtain satisfactory performance of
the automatic control system
[13]
. An integral predictive and
nonlinear robust control strategy to solve the trajectory
tracking problem for a quadrotor helicopter is presented in
this paper
[14]
. This method considers the integral of the
position error in both controllers, zero steady-state error can
be achieved when sustained disturbances are applied to the
system.
However, in actual flight, UAV often need to make a large
maneuver flight, and the amount of control required often
exceeds the maximum output (actuator's saturation
characteristics) that the actuator can provide to reduce the
actual flight control performance
[15]
. In severe cases, it may
cause instability of the whole system. Therefore, the effect
of actuator saturation needs to be considered in flight
control. An adaptive tracking control for a class of uncertain
MIMO nonlinear systems with input constraints is presented
in this paper
[16]
. The auxiliary design system is introduced to
analyze the effect of input constraints, and its states are used
to adaptive tracking control design.
In this paper, an under-actuated quadrotor UAV is proposed
based on the global stable trajectory tracking control
algorithm. Quadrotor UAV system will be divided into
under-actuated position subsystem and attitude subsystem.
For the double closed-loop control system, the position
subsystem controller is designed with the SMC method.
Considered the influence of the input saturation constraint,
ESO and adaptive tracking control are adopted in the outer
loop subsystem. Through the proof of the two methods, the
double closed-loop control system will be global stability.
Finally, the position and attitude angles of the quadrotor
UAV system will track the reference signals.
The remainder of this paper is organized as follows. Section
2 describes the dynamics of the quadcopter UAV system.
Section 3 investigates the sliding mode control together with
Adaptive tracking control of quadrotor UAV system with input constraints
Fan Zhou
1
, Ying-Jiang Zhou
1
, Guo-Ping Jiang
1
, Ning Cao
1
1. College of Automation, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
E-mail:
zhouyj@njupt.edu.cn(Ying-Jiang Zhou)
Abstract: In this paper, sliding mode control(SMC) and adaptive tracking control are given to perform the position and
attitude control of quadrotor unmanned aerial vehicle(UAV) model. For the double closed-loop control system, SMC is
used in the inner loop position subsystem control. In the inner loop subsystem, the virtual attitude angles of attitude
subsystem tracking control are calculated. The adaptive tracking control is applied in the outer loop attitude subsystem
control with input saturation constraints. Subsequently, the auxiliary design system is introduced to analyze the impact of
input constraint, and its states are used for adaptive tracking control design. Then, the internal uncertainties and the
external disturbances will be observed and compensated by extended state observer (ESO).
Finally, simulation studies
are presented to illustrate the effectiveness of the proposed SMC and adaptive tracking control.
Key Words: Quadrotor UAV, SMC, Adaptive tracking control, Double closed-loop control, Input constraints
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2018 IEEE