Robust Adaptive Control of AUVs :an Application to the CR-02 Vehicle
A0025Y. Zhang Shenyang Institute of Automation, Chinese Academy of Sciences
A0014H. H. Chen Shenyang Institute of Automation, Chinese Academy of Sciences
A0013X. S. Feng Shenyang Institute of Automation, Chinese Academy of Sciences
Currently, most of AUVs are survey research vehicles. It is difficult
for AUVs to perform complicated subsea tasks such as subsea oil field
inspection and intervention, docking and recovery. Highly accuracy
dynamic positioning and target tracking of AUVs is one of the keys of
performing above tasks. Due to the poor precision of common control
method, new control methods must be adopted.
Affected by the hydrodynamics and the environment disturbance,
dynamics of AUVs are highly nonlinear, multi-! freedom coupled, and
time varying. Due to the uncertainty of the hydrodynamics and the
complexity of ocean environment, it is difficult to establish highly
accurate dynamics model of AUVs.
The environmental disturbance of the ocean includes wave, ocean
current and imbalance force. The imbalance force is brought from the
imbalance of vehicle structure and hydrodynamics, the imbalance force
model and the ocean current model both are 1st-order and slowly-
varying disturbance. Wave forces can be divided into 1st-order wave
disturbance and 2st-order wave drift force. In this paper, we
supposed the environmental disturbance of the ocean as the combination
of fundamental harmonic, 1st-order harmonic and 2nd-order harmonic.
Dynamics model of AUVs possesses two kinds of uncertainties: model
parameter uncertainty and model structure uncertainty. Aimed at above
uncertainties and the environmental disturbance, there are three
fundamental control methods: robust control, adap! tive control and
This paper presented a ro bust adaptive control law based on
backstepping in order to satisfy with dynamic positioning and target
tracking of highly accuracy. In this control system, environmental
disturbances are looked as an uncertain parameter, the state variable
and uncertain parameter enter the control system through the control
channel, and they satisfy with the matching conditions. The control
law is obtained by replacing the uncertain parameter with its
estimated parameter. The control law guarantees not only that the
state of the control system remains bounded, but also that it tends to
a desired constant value or asymptotically tracks a reference signal.
In this paper, the control system is based on full state feedback, the
state variables are acquired by filter from sensors data. In these
measurements, displacement data are available from Ultra-short base
line, Gyro and Glinometer, velocity data are measured by Doppler,
horizontal and vertical rate Gyro. Finally, full state variables!
are received by filter.
In this paper, this control law is applied to horizontal and vertical
closed-loop control of AUV CR-02.We made some simulations, and
compared with traditional PID controller, the performance has
obviously been improved on precision of dynamic positioning and target
tracking, especially under serious disturbance. Based on simulation,
we will carry out a pool test of AUV CR-02.