Robust Adaptive Dynamic Surface Control Based on Structural Reliability for a Turret-moored Floating Production Storage and Offloading Vessel

Yulong Tuo,Yuanhui Wang,Simon X. Yang,Mohammad Biglarbegian,Mingyu Fu 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.4

For floating production storage and offloading (FPSO) vessels, a dynamic positioning controller is necessary because using only a mooring system is not possible to keep the ship within a predefined region. Position control of the FPSO vessel is extremely challenging due to model uncertainties and unknown control coefficients. This paper develops a new robust adaptive positioning controller consisting of several components: adaptive law, dynamic surface control (DSC) technology, sigmoid tracking differentiator (STD), Nussbaum gain function, and structural reliability index. Model uncertainties can be estimated by the adaptive law derived from the Lyapunov theory. The DSC technology is used to eliminate repeated differentiation by introducing first-order filtering of the virtual control. The chattering-free STD with the characteristics of global fast convergence can estimate the derivatives of model uncertainties that are difficult to calculate directly. Therefore, the DSC and STD techniques make the proposed controller simpler to compute and easier to implement in engineering practice. Most of the traditional controllers require the information about the control coefficients to guarantee the stability of the closed-loop system while the Nussbaum gain function can remove the requirement for a priori knowledge of the sign of control coefficients. The capacity of the mooring system can be fully utilized to position the FPSO vessel by adjusting the structural reliability index on the premise of ensuring the safety of mooring lines, and hence less control effort is needed for the positioning controller. Simulations using two sets of system parameters demonstrate the proposed controller’s effectiveness. In addition, a qualitative comparison with the adaptive backstepping controller shows that our proposed controller is computationally more efficient and does not require a priori knowledge of the sign of control coefficients. A quantitative comparison with robust adaptive controller without the structural reliability shows that less control effort is needed using our proposed controller.

Reliability-based Event Driven Backstepping Positioning Control for a Turret-moored FPSO Vessel with Unknown Slow Time-varying Disturbances

Yulong Tuo,ShashaWang,Chen Guo,Haomiao Yu,Zhipeng Shen 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.2

In this paper, an event driven backstepping positioning controller based on the structural reliability is developed for a turret-moored floating production storage and offloading (FPSO) vessel with unknown slow timevarying disturbances. The mathematical model of the FPSO vessel is given at first. Secondly, to make full use of the positioning capability of mooring system while ensuring the safety of mooring lines, a continuous backstepping positioning controller is designed based on the structural reliability of the mooring system; in the meanwhile, a disturbance observer is designed to handle the unknown disturbances. Then, the proposed event driven positioning controller is achieved based on the designed continuous controller by designing suitable event driven conditions, which can determine the updated time instants of the event driven positioning controller. The proposed positioning controller can not only guarantee the uniform ultimate boundness of the errors for structural reliability and heading but also ensure that no Zeno behavior occurs. Finally, the simulations demonstrate that the proposed event driven positioning controller’s performance while reducing the execution times of FPSO vessel’s actuators.

Robust output feedback control for dynamic positioning of turret-moored vessels based on bio-inspired state observer and online constructive fuzzy system

Tuo Yulong,Wang Shasha,Guo Chen,Gao Shuang 대한조선학회 2022 International Journal of Naval Architecture and Oc Vol.14 No.1

This paper investigates the dynamic positioning control of turret-moored vessels with uncertainties, unknown disturbances and velocities. Firstly, a bio-inspired state observer is proposed based on the bioinspired neural dynamics model to estimate unknown velocities without vessel dynamics model. Meanwhile, an online constructive fuzzy approximator is designed to approximate uncertainties and unknown disturbances. To ensure fuzzy rules adequate and parsimonious, an online constructive scheme is proposed to adjust the fuzzy system structure without any prior knowledge. Based on the designed state observer and fuzzy approximator, a reliability-based robust output-feedback controller is proposed to make the reliability and heading converge to desired values. A reliability-based matrix is applied into the adaptive fuzzy parameter update law to simplify the stability analysis of closed-loop control system. The convergence of reliability can ensure full utilization of mooring system to maintain the vessel within allowable region. Finally, simulations and comparisons show the performance of proposed methods.

Finite-time extended state observer-based area keeping and heading control for turret-moored vessels with uncertainties and unavailable velocities

Tuo Yulong,Wang Shasha,Guo Chen 대한조선학회 2022 International Journal of Naval Architecture and Oc Vol.14 No.1

This paper investigates the finite-time extended state observer-based Dynamic Positioning (DP) control of turret-moored vessels with unavailable velocities and uncertainties. The control objective is to assist the mooring system of vessel in achieving area keeping and heading control. Firstly, unavailable velocities and uncertainties are estimated simultaneously by the designed finite-time Extended State Observer (ESO), where finite-time convergence and high accuracy of estimated values are guaranteed. Then, a reliability index is introduced to quantify the breakage probability of mooring lines. Based on estimated values and reliability index, a finite-time DP controller is proposed for area keeping and heading control of turret-moored vessels. The proposed controller can improve utilization efficiency of mooring system and guarantee finite-time convergence of all signals in closed-loop control system. Meanwhile, a saturation function is integrated into the controller to decrease the thrusters’ energy consumption. Finally, simulations and comparisons demonstrate the performance of finite-time ESO and DP controller.

Weather optimal area-keeping control for underactuated autonomous surface vehicle with input time-delay

Wang Shasha,Tuo Yulong,Wang Dan 대한조선학회 2022 International Journal of Naval Architecture and Oc Vol.14 No.1

The problem of the underactuated Autonomous Surface Vehicle (ASV) area-keeping control under unknown slow time-varying external environment disturbances and input time-delay, an integral timedelay sliding mode control algorithm based on weather optimal intermittent strategy is proposed in this article. Firstly, integral time-delay sliding mode control law is constructed, with controller parameters chosen according to the upper bound of time-delay. In the control law, a geometric updating rule is designed for the virtual suspension point, which enables ASV at a particular small area with a weather optimal heading. And, weather optimal intermittent strategy is developed to extend the area-keeping control method, while reducing ASV energy consumption. Besides, the closed-loop system is globally asymptotically stable through Lyapunov-Krasovskii analysis. Finally, the performance of the proposed algorithm is illustrated through the simulation examples.

Model-free adaptive discrete-time full-order sliding mode constrained control for path following of unmanned surface vessels

Gao Shuang,Hu Hongli,Tuo Yulong,Liang Wei,Huang Zhongyi 대한조선학회 2023 International Journal of Naval Architecture and Oc Vol.15 No.-

Considering the dynamic uncertainty, input saturation, and the discrete characteristics of digital control, a practical path following method is proposed for unmanned surface vessels (USV). Online identification for the heading model with uncertainty is presented based on a data-driven technique. Further, a constrained full-order terminal sliding manifold is constructed based on an auxiliary system to solve the input saturation. A full-order sliding mode heading controller is designed for USV in discrete-time form and the stability analysis is provided. Additionally, integral line of sight (ILOS) guidance law is introduced to generate the desired signal for the path following of USV. Simulations and experiments show that the proposed method is effective to realize tracking the desired path and has better performance than the existing popular method.