Int. J. Appl. Math. Comput. Sci., 2015, Vol. 25, No. 1, 175–187
DOI: 10.1515/amcs-2015-0013
SIMULTANEOUS STATE AND PARAMETER ESTIMATION BASED ACTUATOR
FAULT DETECTION AND DIAGNOSIS FOR AN UNMANNED HELICOPTER
CHONG WU
a, b
,JUNTONG QI
a,∗
,DALEI SONG
a
,XIN QI
a, b
,JIANDA HAN
a
a
State Key Laboratory of Robotics, Shenyang Institute of Automation
Chinese Academy of Sciences, No. 114 Nanta Street, Shenyang, Liaoning Province, China
e-mail: {wuchong,qijt,qixin,daleisong,jdhan}@sia.cn
b
University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, China
Simultaneous state and parameter estimation based actuator fault detection and diagnosis (FDD) for single-rotor unmanned
helicopters (UHs) is investigated in this paper. A literature review of actuator FDD for UHs is given firstly. Based on
actuator healthy coefficients (AHCs), which are introduced to represent actuator faults, a combined dynamic model is
established with the augmented state containing both the flight state and AHCs. Then the actuator fault detection and
diagnosis problem is transformed into a general nonlinear estimation one: given control inputs and the measured flight
state contaminated by measurement noises, estimate both the flight state and AHCs recursively in each time-step, which
is also known as the simultaneous state and parameter estimation problem. The estimated AHCs can further be used for
fault tolerant control (FTC). Based on the existing widely used nonlinear estimation methods such as the unscented Kalman
filter (UKF) and the extended set-membership filter (ESMF), three kinds of adaptive schemes (KF-UKF, MIT-UKF and
MIT-ESMF) are proposed by our team to improve the actuator FDD performance. A comprehensive comparative study
on these different estimation methods is given in detail to illustrate their advantages and disadvantages when applied to
unmanned helicopter actuator FDD.
Keywords: actuator fault detection and diagnosis, unmanned helicopter, Kalman filter, set-membership filter, adaptive
scheme.
1. Introduction
Helicopters have been widely used in both civilian and
military fields due to their capabilities of hovering,
vertical take-off and landing, low-altitude and low-speed
flight. In the past two decades, the unmanned helicopter
(UH) has become an attractive research topic in academic
communities worldwide and numerous research groups
have designed their own unmanned helicopter platforms
such as Yamaha-RMAX of Carnegie Mellon University
(Amidi et al., 1998), GTMax of the Georgia Institute of
Technology (Johnson and Schrage, 2003), ServoHeli of
the Shenyang Institute of Automation, Chinese Academy
of Sciences (Qi et al., 2009) and the Lion unmanned aerial
vehicle (UAV) of the National University of Singapore
(Cai et al., 2011b).
The increasing utilization of UHs in civilian
environment demands higher reliability and safety to
∗
Corresponding author
avoid potential accidents. However, structure features
of the helicopter induce that it does not have the same
graceful degradation property as other aerial vehicles,
such as fixed-wing aircraft and airships, under faults
(degradation) or failures (out of order) (Heredia et al.,
2008). Furthermore, the normally small size, light weight
and compact structure characteristics of UHs make the
redundancy of on-board sensors and actuators redundancy
extremely limited. As is known, the main rotor of the
helicopter is used not only to provide the lift but also to
control the helicopter. In order to control the main rotor,
a swashplate is used. A small UH’s swashplate, which
mainly performs the lateral, longitudinal and vertical
motion to control the UH through three actuators, is
illustrated in Fig. 1. There is no redundancy among
these actuators and the actuator fault will directly lead to
malfunction of the swashplate.
In this paper, actuator faults of UHs are considered.
Typically, actuator faults mainly include constant output
