scholarly journals Station-Keeping Control of Autonomous and Remotely-Operated Vehicles for Free Floating Manipulation

2021 ◽  
Vol 9 (11) ◽  
pp. 1305
Author(s):  
Ningning Ding ◽  
Yuangui Tang ◽  
Zhibin Jiang ◽  
Yunfei Bai ◽  
Shixun Liang
Keyword(s):  
Direct Method ◽  
Reference Signal ◽  
Station Keeping ◽  
Remotely Operated Vehicles ◽  
Model Uncertainties ◽  
External Disturbances ◽  
Model Free ◽  
Control Scheme ◽  
System States ◽  
The Time Domain

This paper investigates the station-keeping control of autonomous and remotely-operated vehicles (ARVs) for free-floating manipulation under model uncertainties and external disturbances. A modified adaptive generalized super-twisting algorithm (AGSTA) enhanced by adaptive tracking differentiator (ATD) and reduced-order extended state observer (RESO) is proposed. The ATD is used to obtain the smooth reference signal and its derivative. The RESO is used to estimate and compensate for the model uncertainties and external disturbances in real-time, which enhances the robustness of the controller. The modified AGSTA ensures the fast convergence of the system states and maintains them in a predefined neighborhood of origin without overestimating control gains. Besides, the proposed new variable gain strategy completely avoids the control gains vibrating near the set minimum value. Thanks to the RESO, the proposed controller is model-free and can be easily implemented in practice. The stability of the closed-loop system is analyzed based on Lyapunov’s direct method in the time domain. Finally, the proposed control scheme is applied to the station-keeping control of Haidou-1 ARV, and the simulation results confirm the superiority of the proposed control scheme over the original AGSTA.

scholarly journals Disturbance Observer-Based Nonsingular Terminal Sliding Mode Control for Spacecraft Electromagnetic Docking

2020 ◽  
Vol 2020 ◽  
pp. 1-20
Author(s):  
Jinghui Zhang ◽  
Guoqiang Zeng ◽  
Shifeng Zhang
Keyword(s):  
Sliding Mode Control ◽  
Magnetic Moment ◽  
Disturbance Observer ◽  
Field Model ◽  
Sliding Mode ◽  
Far Field ◽  
Model Uncertainties ◽  
External Disturbances ◽  
Control Scheme ◽  
On Line

This paper presents a novel nonlinear sliding mode control scheme that combines on-line model modification, a nonlinear sliding mode controller, and a disturbance observer to solve the essential problems in spacecraft electromagnetic docking control, such as model uncertainties, unknown external disturbances, and inherent strong nonlinearity and coupling. An improved far-field model of electromagnetic force which is much more accurate than the widely used far-field model is proposed to enable the model parameters to be on-line self-adjusting. Then, the relationship between magnetic moment allocation and energy consumption is derived, and the optimal direction of the magnetic moment vector is obtained. Based on the proposed improved far-field model and the research results of magnetic moment allocation law, a fast-nonsingular terminal mode controller driven by a disturbance observer is designed in the presence of model uncertainties and external disturbances. The proposed control method is guaranteed to be chattering-free and to possess superior properties such as finite-time convergence, high-precision tracking, and strong robustness. Two simulation scenarios are conducted to illustrate the necessity of modifying the far-field model and the effectiveness of the proposed control scheme. The simulation results indicate the realization of electromagnetic soft docking and validate the merits of the proposed control scheme. In the end of this paper, some conclusions are drawn.

scholarly journals Fixed-Time Trajectory Tracking Control of Autonomous Surface Vehicle with Model Uncertainties and Disturbances

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Jiawen Cui ◽  
Haibin Sun
Keyword(s):  
Trajectory Tracking ◽  
Tracking Control ◽  
Sliding Mode ◽  
Fixed Time ◽  
Convergence Time ◽  
Model Uncertainties ◽  
External Disturbances ◽  
Trajectory Tracking Control ◽  
Integral Sliding Mode ◽  
Control Scheme

The issue of fixed-time trajectory tracking control for the autonomous surface vehicles (ASVs) system with model uncertainties and external disturbances is investigated in this paper. Particularly, convergence time does not depend on initial conditions. The major contributions include the following: (1) An integral sliding mode controller (ISMC) via integral sliding mode surface is first proposed, which can ensure that the system states can follow the desired trajectory within a fixed time. (2) Unknown external disturbances are absolutely estimated by means of designing a fixed-time disturbance observer (FTDO). By combining the FTDO and ISMC techniques, a new control scheme (FTDO-ISMC) is developed, which can achieve both disturbance compensation and chattering-free condition. (3) Aiming at reconstructing the unknown nonlinear dynamics and external disturbances, a fixed-time unknown observer (FTUO) is proposed, thus providing the FTUO-ISMC scheme that finally achieves trajectory tracking of ASVs with unknown parameters. Finally, simulation tests and detailed comparisons indicate the effectiveness of the proposed control scheme.

Discrete-Time Adaptive Controller Based on Estimated Pseudopartial Derivative and Reaching Sliding Condition

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Chidentree Treesatayapun
Keyword(s):  
Discrete Time ◽  
Sliding Mode ◽  
Direct Method ◽  
Experimental System ◽  
Adaptive Controller ◽  
Current Control ◽  
Lyapunov Direct Method ◽  
Model Free ◽  
Control Scheme ◽  
Time Systems

An adaptive controller based on sliding mode condition is developed with estimated pseudopartial derivative (PPD) of data-driven scheme. The controlled plant is considered as a class of unknown discrete-time systems with only output feedback, which allows the proposed controller to be applicable for practical plants operated by computerization systems. The convergence of estimated PPD is analyzed by Lyapunov direct method under reasonable assumptions. The control law is derived by the estimated PPD and reaching condition of sliding surface as a model-free of controlled plant. The performance of the proposed control scheme is validated by theoretical analysis and experimental system with direct current (DC) motor current control.

Active Noise Control in a Y-Shaped Duct: Simulation and Experimental Results

1998 ◽  
Vol 5 (1) ◽  
pp. 17-25
Author(s):  
Ronaldo Fernandes Nunes ◽  
José Roberto De França Arruda ◽  
José Maria Campos Dos Santos
Keyword(s):  
Noise Control ◽  
Reference Signal ◽  
Active Noise Control ◽  
Experimental Results ◽  
Step Size ◽  
Active Noise ◽  
Control Scheme ◽  
Perturbation Source ◽  
The Time Domain ◽  
And Control

There are different approaches to active noise control (ANC). The time domain Filtered-X LMS adaptive control scheme is currently used in most applications. The purpose of this paper is to describe an experiment consisting of a Y-shaped duct with two loudspeakers attached to the two branches of the Y duct. One of the loudspeakers acts as the perturbation source and the other acts as the control source. Tonal noise control is investigated, and control implementation issues such as number of filter weights, value of step-size parameter, and sampling frequency are discussed. The reference signal is taken from the signal sent to the perturbation loudspeaker and the error signal is taken from a microphone that can be placed anywhere along the stem of the Y-shaped duct. Simulations and experimental results are presented. The setup is simple and may be easily implemented for leaching purposes.

scholarly journals Output Feedback Cooperative Dynamic Positioning Control for an Unactuated Floating Object Using Multiple Vessels

2021 ◽  
Vol 9 (5) ◽  
pp. 463
Author(s):  
Guoqing Xia ◽  
Chuang Sun ◽  
Bo Zhao
Keyword(s):  
Output Feedback ◽  
Cooperative Control ◽  
Control Method ◽  
Reference Signal ◽  
Dynamic Positioning ◽  
Model Uncertainties ◽  
Positioning Control ◽  
State Observers ◽  
Control Scheme ◽  
Floating Object

This paper proposes an output feedback cooperative dynamic positioning control scheme for an unactuated floating object using multiple vessels under model uncertainties and environmental disturbances. The floating object is connected to multiple vessels through towlines. At first, nonlinear extended state observers are developed for the floating object and vessels to reconstruct the unmeasured velocity and to estimate the model uncertainties and disturbances. Second, observer-based controllers are designed for the floating object and vessels to drive the floating object to track the reference signal and to achieve the cooperative control of multiple vessels, respectively. The salient features of the proposed control scheme are presented as follows. Firstly, by design the object controller, the tracking performance of the object is improved. Secondly, according to the required force of the floating object, the time-varying formation of vessels is obtained by using the towline attachment geometry of the floating object, control allocation and a towline model. It is shown that all signals in closed-loop system are bounded via Lyapunov analysis. Simulation study is carried out to verify the effectiveness of proposed control method.

scholarly journals Neuro-Sliding Control for Underwater ROV’s Subject to Unknown Disturbances

Sensors ◽  
2019 ◽  
Vol 19 (13) ◽  
pp. 2943 ◽  
Author(s):  
Luis Govinda García-Valdovinos ◽  
Fernando Fonseca-Navarro ◽  
Joanes Aizpuru-Zinkunegi ◽  
Tomas Salgado-Jiménez ◽  
Alfonso Gómez-Espinosa ◽  
...  
Keyword(s):  
Sliding Mode ◽  
Tracking Error ◽  
Fast Response ◽  
External Disturbances ◽  
Sliding Control ◽  
Model Free ◽  
Control Scheme ◽  
Parameter Variations ◽  
Unknown Disturbances ◽  
Chattering Free

Proposed in this paper is a model-free and chattering-free second order sliding mode control (2nd-SMC) in combination with a backpropagation neural network (BP-NN) control scheme for underwater vehicles to deal with external disturbances (i.e., ocean currents) and parameter variations caused, for instance, by the continuous interchange of tools. The compound controller, here called the neuro-sliding control (NSC), takes advantage of the 2nd-SMC robustness and fast response to drive the position tracking error to zero. Simultaneously, the BP-NN contributes with its capability to estimate and to compensate online the hydrodynamic variations of the vehicle. When a change in the vehicle’s hydrodynamics occurs, the 2nd-SMC may no longer be able to compensate for the variations since its feedback gains are tuned for a different condition; thus, in order to preserve the desired performance, it is necessary to re-tune the feedback gains, which a cumbersome and time consuming task. To solve this, a viable choice is to implement a BP-NN control scheme along with the 2nd-SMC that adds or removes energy from the system according to the current condition it is in, in order to keep, or even improve, its performance. The effectiveness of the proposed compound controller was supported by experiments carried out on a mini-ROV.

Finite-time model-free trajectory tracking control for overhead cranes subject to model uncertainties, parameter variations and external disturbances

2019 ◽  
Vol 41 (12) ◽  
pp. 3516-3525 ◽  
Author(s):  
Menghua Zhang
Keyword(s):  
Trajectory Tracking ◽  
Finite Time ◽  
Sliding Mode ◽  
Overhead Crane ◽  
Model Uncertainties ◽  
Asymptotic Results ◽  
External Disturbances ◽  
Trajectory Tracking Control ◽  
Model Free ◽  
Parameter Variations

The payload mass and the cable length are always different/uncertain for various transportation tasks and external disturbances that accompany industrial overhead crane systems. In addition, existing control methods can obtain merely asymptotic results. To solve the aforementioned problems, an accurate model-free trajectory tracking controller subject to finite time convergence for overhead crane systems is proposed based on the suitably defined non-singular terminal sliding vector. Moreover, the proposed controller is absolutely continuous, addressing the limitations and shortcomings of the traditional sliding mode control. Lyapunov techniques are used to prove that the proposed controller guarantees finite-time tracking result and the finite time T is calculated. Simulation and experimental results are included to demonstrate the robustness of the proposed controller with respect to model uncertainties, parameter variations and external disturbances.

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