Nonlinear Modeling for a Water-Jet Propulsion USV: An Experimental Study

Abstract

Abstract-Although unmanned surface vehicles (USVs) have been extensively researched and applied to many typical scenarios, high-performance autonomous control is still an open problem. One of their major problem stems from the difficulty in constructing a sufficient accurate and sufficient simple control-oriented dynamics model. Owing to the highly complicated physical mechanisms of hydrodynamics, USV systems possess strong nonlinearities and coupling, which make it exceptionally difficult to develop an accurate model structure. In real applications, extensively existing uncertainties, such as external disturbances due to wind, wave, current, and measurement noise in the onboard sensor, will unavoidably influence identification precision with respect to the parameters in the USV's model. Thus, in this paper, a new kind of nonlinear modeling scheme-the active modeling enhanced quasi-linear parameter-varying (qLPV) model-is proposed for a water-jet propulsion USV system. First, a qLPV-structured model is derived by simplifying the real dynamics model, which has a simple quasi-linear structure and can approximate the nonlinearities of the hydrodynamics. Subsequently, a nonlinear version of the Kalman filter-based active modeling method is proposed to provide online estimates of the unstructured model to eliminate the errors due to the structure inaccuracy between the qLPV-structured model and the real system. Finally, the newly proposed modeling scheme is tested on a real USV system and its superiority is shown through comparisons to some other traditional modeling methods.Index Terms-Active modeling, quasi-linear-parametervarying (qLPV) system, unmanned surface vehicles (USVs), unscented Kalman filter (UKF).

Real-time Riverbank Line Detection for USV System

“…In this paper, for the purpose of verify the effectiveness of our riverbank line detection algorithm, lots of experiments were done in a series of different environments. The USV platform, as in [11], designed in Shenyang Institute of Automation, Guangzhou, Chinese Academy of Sciences, which is displayed out Fig. 8.…”

AutoTuning Environment for Static Obstacle Avoidance Methods Applied to USVs

“…Finally, a USV model must be used to evaluate the new autotuning environment. In the current state of the art different mathematical models of USVs have been proposed [22,26,28,[47][48][49], most of them for vessels of small length. This is mainly because one of the advantages of this kind of vehicles is that, as these do not need a crew, the size of the vehicle can be reduced, increasing its manoeuvrability and reducing costs [1,2].…”

“…This is mainly because one of the advantages of this kind of vehicles is that, as these do not need a crew, the size of the vehicle can be reduced, increasing its manoeuvrability and reducing costs [1,2]. Many of these models [22,26,28,47,48] simplify the dynamics of the vessel since they do not take into account the modelling of the actuators and the effect of the ocean current. In order to make realistic the simulation environment proposed in this work, a mathematical model is proposed for an USV of 9.2 m of length.…”

Direct Sailing Variable Acceleration Dynamics Characteristics of Water-Jet Propulsion with a Screw Mixed-Flow Pump

“…The "Fridsma Hull" flow experiment was utilized to study the gliding phenomenon in maritime transport. The Nomoto model was a frequently used model that describes the basic motion of an unmanned surface vehicle (USV) [13][14][15][16]. Jianda Han [17] combined the USV motion model with experimental research and gave a nonlinear mathematical model of water-jet propulsion.…”